is produced by piezo-electric principles. Image production is deter- and disposal. Its pharmacological properties allow it to be easily bound
mined by attenuation and reflection as the beam passes through tissues. to various tracers and it emits gamma rays that are of suitable energy
Attenuation is caused by the loss of energy due to absorption, reflection for medical imaging. In addition to 99mtechnetium, the most com-
and refraction in soft tissues, resulting in a reduction in signal intensity. mon intravenous radionuclides used in nuclear medicine are 123iodine
Reflection of sound waves within the range of the receiver produces the and 131iodine, 201thallium, 67gallium, 18fluorodeoxyglucose (FDG) and
image, and the echotexture is dependent on tiny differences in acoustic 111indium-labelled leukocytes. The most common gaseous/aerosol radio-
impedance between different tissues. Blood flow and velocity can be nuclides used are 133xenon, 81mkrypton, 99mtechnetium (Technegas) and
measured (using the Doppler principle) in duplex mode. 99mtechnetium diethylene triamine pentaacetic acid (DTPA).
Techniques such as harmonic imaging and the use of ultrasound The images obtained from nuclear medicine imaging can be single
contrast agents (stabilized microbubbles) have enabled non-invasive or multiple. Image sets may be represented by time sequence imaging
determination of myocardial perfusion. These contrast agents also (e.g. cine), such as dynamic imaging or cardiac gated sequences, or by
clearly improve the detection of metastases in the liver and spleen. spatial sequence imaging, where the gamma camera is moved relative
Ultrasound is the most common medical imaging technique for pro- to the patient, e.g. in SPECT imaging. Spatial sequence imaging allows
ducing elastograms, in which stiffness or strain images of soft tissue are the images to be presented as a slice-stack much in the way that CT or
used to detect or classify tumours. Cancer is 5–28 times stiffer than the MRI images are displayed. It may also be fused with concomitant CT
background of normal soft tissue; when a mechanical compression or or MRI to provide combined physiological and anatomical imaging.


vibration is applied, a tumour deforms less than the surrounding tissue. A PET scan is a specialized type of nuclear medicine imaging that
Elastography may be used, for example, to measure the stiffness of the measures important body functions, such as blood flow, oxygen use or
liver in vivo or in the detection of breast or thyroid tumours. A correla- glucose metabolism. It involves short-lived radioactive tracer isotopes
tion between liver elasticity and the cirrhosis score has been shown (Yeh that emit positrons (positively charged subatomic particles with the
et al 2002, Foucher et al 2006). same mass and magnitude of charge as electrons). The radioisotopes
Interpretation of anatomy and pathology from static ultrasound are chemically incorporated into biologically active molecules: most
images is more difficult than that from other imaging modalities: commonly, the sugar FDG (2-deoxy-2-[fluorine-18]fluoro-D-glucose).
compare the real-time nature ultrasound in Video 14.1 with the static An hour after injection, FDG becomes concentrated into the tissues of
images in Fig 14.4. The technique is highly operator-dependent and interest; images are obtained as the isotope undergoes positron emis-
provides unique information on tissue structure and form not obtained sion decay. A positron travels only a few millimetres before reacting
from other imaging techniques. with an electron by annihilation, producing a pair of gamma photons
that move in opposite directions. The PET scan detectors process only
those photon pairs that are detected simultaneously (coincident detec-
Nuclear medicine
tion) to create an image of tissue activity with respect to that particular
isotope. These images may subsequently be fused with CT or MR
Historically, the field of nuclear medicine began in 1946 when images. The short half-life of the isotopes limits PET imaging; close
radio active iodine was administered as an ‘atomic cocktail’ to treat access to a cyclotron for generation of the isotopes plays an important
thyroid cancer. Since that time, nuclear medicine has advanced to the role in the feasible location of a PET scanner. Typical isotopes used in
point where it was recognized in the early 1970s as a diagnostic sub- medical imaging and their half-lives are: 11carbon (about 20 min),


specialty. 13nitrogen (about 10 min), 13oxygen (about 2 min) and 18fluorine
Unlike diagnostic radiology, where an image is created by passing (about 110 min).
energy through the body from an external source, nuclear medicine
creates an image by measuring the radiation emitted from tracers taken
Angiography/interventional radiology
internally. Overall, the radiation dosages are comparable with CT and
vary depending on the examination. Nuclear medicine also differs from
most other imaging modalities in that the tests demonstrate the physio- Angiographic imaging was first described in 1927, when Egas Moniz, a
logical function of a specific area of the body. In some instances, this physician and neurologist, introduced contrast X-ray cerebral angiogra-
physiological information may be fused with the more anatomical phy. (Moniz was awarded the Nobel Prize for his work in 1949.) In
imaging of CT or MRI, combining the strengths of anatomy and func- 1953, the field was revolutionized by the Seldinger technique, in which
tion for diagnosis. no sharp needles remained inside the vascular lumen during imaging.
Nuclear medicine uses pharmaceuticals that have been labelled with Although angiography initially involved X-ray and fluoroscopic imaging
a radionuclide (radiopharmaceuticals) and which are administered to of blood vessels and organs of the body after injecting radiopaque
patients by intravenous injection, ingestion or inhalation (the method contrast agents into the blood stream, it has evolved to encompass so
of administration depends on the type of examination and the organ much more. Many of the procedures currently performed by angiogra-
or organ process to be imaged). Emitted radiation is detected and phy may be diagnostic; following the advent of minimally invasive
imaged with specialized equipment such as gamma cameras, positron procedures performed with image guidance, the name of the discipline
emission tomography (PET) or single photon emission computed changed to interventional radiology (or vascular and interventional
tomography (SPECT). Radiation may be measured from parts of the radiology).
body by the use of probes, or samples may be taken from patients and Angiograms are typically performed by gaining access to the blood
measured in counters. vessels, through either the femoral artery, femoral vein or jugular vein,


Radiopharmaceuticals may be used to image a disease process or to depending on the area of interest to be imaged (e.g. cerebral, coronary
treat diseases. Those used for imaging emit a gamma ray (γ) and those or pulmonary angiograms). Following vascular access, catheters are
used for treatment emit a beta (β) particle. Gamma rays are of higher directed to the specific location to be imaged by the use of guidewires,
energy in order to pass through the body and be detected by a detection and contrast agents are injected through these catheters to visualize the
camera, whereas β particles travel only short distances and emit their vessels or the organ with X-ray imaging. Imaging of the arterial and


Technical aspects and applications of diagnostic radiology
e69
1.7
yraTneMMoc
venous circulation of the arms and legs may demonstrate peripheral attenuation coefficient of all the tissues in the path of the X-ray beam
vascular disease. form the image. CT obtains a series of different angular X-ray projec-
Treatment and/or interventions can often be performed through tions that are processed by a computer to give a section of specified
similar catheter-based examinations. Such procedures might involve thickness. The CT image comprises a regular matrix of picture elements
angioplasties, where a balloon mechanism is placed across an area of (pixels). All of the tissues contained within the pixel attenuate the X-ray
narrowing (stenosis) in a vessel or lumen. With controlled inflation of projections and result in a mean attenuation value for the pixel. This
the balloon, the area of narrowing can be widened. value is compared with the attenuation value of water and is displayed
Imaging in diagnostic or interventional procedures may produce still on a scale (the Hounsfield scale). Water is said to have an attenuation
or motion (cine) images. The technique often used, digital subtraction of 0 Hounsfield units (HU); air typically has an HU number of −1000;
angiography (DSA), involves taking images at 2–30 frames per second fat is approximately −100 HU; soft tissues are in the range +20 to
to allow imaging of the flow of blood through vessels. A preliminary +70 HU; and bone is usually greater than +400 HU.
image of the area is taken before the contrast is injected; this ‘mask’ Modern multislice helical CT scanners can obtain images in sub-
image is then electronically subtracted from all subsequent images, second times, and imaging of the whole body from the top of the head
leaving only the vessels filled with contrast. For optimal subtraction, to the thighs can take as little as a single breath-hold of only a few
the patient must remain motionless. seconds. The fast scan times allow dynamic imaging of arteries and
Angiograms of the heart may be performed to visualize the size and veins at different times after the injection of intravenous contrast agents.
contractility of the chambers and the anatomy of the coronary vessels. The continuous acquisition of data from a helical CT scanner allows
The thorax may also be studied to evaluate the pulmonary arteries and reconstruction of an image in any plane (multiplane reconstruction,


veins for vascular malformations, blood clots and possible origins of MPR), commonly sagittal and coronal, as may be seen in many of the
haemoptysis. In the investigation of atherosclerotic disease, vascular images throughout this forty-first edition of Gray’s Anatomy. This
malformations or tumoral vascularization, the neck is often imaged in orthogonal imaging greatly improves the understanding of the three-
order to visualize the vessels that supply the brain in their entirety, from dimensional aspects of radiological anatomy and now forms part of the
the points at which they arise from the aortic arch to their termination standard practice of assessing disease.
as cerebral vessels. Renal artery imaging may elucidate the cause of No specific preparation is required for most CT examinations of the
hypertension in selected patients, and imaging of the mesenteric vessels brain, spine or musculoskeletal system. Studies of the chest, abdomen
may identify the origin of gastrointestinal bleeding or mesenteric and pelvis, and those of the brain with complex histories, usually
angina. require intravenous contrast medium that contains iodine because this
In addition to angiograms and venograms, the field of interventional defines vascular relationships and differentiates normal and pathologi-
radiology also includes such procedures as coil embolization of aneu- cal soft tissues more effectively. Opacification of the bowel in CT studies
rysms and vascular malformations; balloon angioplasty and stent place- of the abdomen and pelvis may be accomplished by oral ingestion of
ment; chemoembolization directly into tumours; drainage catheter a water-soluble contrast medium from 24 hours prior to the examina-
insertion; embolization (e.g. uterine artery for treatment of fibroids); tion, in order to outline the colon, combined with further oral intake
thrombolysis to dissolve blood clots; tissue biopsy (percutaneous or 0–60 minutes prior to the scan, in order to outline the stomach and
transvascular); radiofrequency ablation and cryoablation of tumours; small bowel. This procedure is much less frequently performed with the
line insertions for specialized vascular access; inferior vena cava filter latest generation of scanners, which exquisitely differentiate various
placements; vertebroplasty; nephrostomy placement; gastrostomy tube enhancing layers within the bowel wall. Occasionally, direct insertion


placement for feeding; dialysis access; transjugular intrahepatic porto- of rectal contrast to show the distal large bowel may be required.
systemic shunt (TIPS) placement; biliary interventions; and, most Generally, all studies are performed with the patient supine and
recently, endovenous laser ablation of varicose veins. images are obtained in the transverse or axial plane. Modern CT scan-
ners allow up to 25° of gantry angulation, which is particularly valuable
in spinal imaging. Occasionally, direct coronal images are obtained in
Computed tomography
the investigation of cranial and maxillofacial abnormalities; in these
cases, the patient lies prone with the neck extended and the gantry
The limitation of all plain radiographic techniques is the two- appropriately angled, but this technique has largely been superseded
dimensional representation of three-dimensional structures; the linear by the orthogonal imaging described above.
REFERENCES
Desser TS, Jeffrey RB 2001 Tissue harmonic imaging techniques: physical Nucifora PG, Verma R, Lee SK et al 2007 Diffusion-tensor MR imaging and
principles and clinical applications. Semin Ultrasound CT MR 22: tractography: exploring brain microstructure and connectivity. Radiol-
1–10. ogy 245:367–84.
Foucher J, Chanteloup E, Vergniol J et al 2006 Diagnosis of cirrhosis by Yeh WC, Li PC, Jeng YM et al 2002 Elastic modulus measurements of human
transient elastography (FibroScan): a prospective study. Gut 55:403–8. liver and correlation with pathology. Ultrasound Med Biol 28:467–74.


COMMENTARY
7.2
Endobronchial ultrasound
Natalie M Cummings
History tively, compared to 69% and 88% for EBUSTBNA alone. A more recent
study of 44 patients, where the same operator performed EBUSTBNA
and then EUSFNA by inserting the EBUS bronchoscope into the
It is more than 35 years since the first description of blind transbron
oesophagus, found that the sensitivity, specificity and accuracy of
chial needle aspiration (TBNA) biopsies of paratracheal masses was
mediastinal lymph node staging using combined EBUS/EUSFNA were
published (Wang et al 1978). Prior to this, surgery had been the only
all 100%, compared to 79%, 100% and 84%, respectively, for EBUS
way to obtain tissue from mediastinal masses or lymph nodes. TBNA
alone (Lee et al 2014). The ASTER trial randomized 241 patients to
is less invasive than surgery but the blind nature of the technique dict
either combined EBUS/EUSFNA or conventional surgical staging
ates that sampling only bulky masses or nodal tissue results in an
(Annema et al 2010). Where endoscopic staging showed no evidence of
acceptable yield. In the early 1990s, the first report of the new technique
locally advanced disease, the patient underwent surgical staging (n = 65).
of ‘endobronchial sonography’ appeared (Hürter and Hanrath 1992).
Sensitivity was significantly greater for combined surgical/endoscopic
A small ultrasound catheter was passed through the working channel
staging (94% versus 79%, P = 0.02) with similar NPVs (93% versus 86%,
of a bronchoscope, giving a 360° (radial) ultrasound image. Biopsies
P = 0.18) and complication rates. A headtohead study of EBUSTBNA
could be taken by inserting standard biopsy forceps through a sheath
versus the surgical approach of videoassisted mediastinoscopy (VAM)
left in place to mark the correct position once the ultrasound catheter
in 153 patients was published in 2011 (Yasufuku et al 2011). No signifi


was removed. In 2003, the first report of a prototype bronchoscope,
cant differences were found between the two procedures in determining
incorporating a curved linear array electronic transducer at the end of
the true pathological Nstage, although the authors admitted that the
the bronchoscope, was published (Krasnik et al 2003). When the trans
EBUSTBNA yield may have been improved by the fact that the proce
ducer was closely applied to the bronchial wall, ultrasound scanning of
dures were all carried out under general anaesthetic by thoracic sur
mediastinal structures (to a depth of 5 cm) was possible and a 22gauge
geons who were extremely familiar with mediastinal anatomy. At
needle inserted through the biopsy channel and into the mass in ques
present, the European Society of Thoracic Surgeons continue to recom
tion was visible in real time. This meant that smaller lesions could be
mend that patients with mediastinal lymphadenopathy on PET/CT and
biopsied more accurately, with reduced potential for the wrong area
negative endoscopic staging proceed to VAM because of the higher NPV
to be sampled inadvertently. This new biopsy technique was termed
(de Leyn et al 2014). However, mediastinoscopy can be avoided if endo
endobronchial ultrasound (EBUS)TBNA or fine needle aspiration
scopic staging is positive.
(EBUSFNA).
Technique Other uses
Although the initial procedures took place under general anaesthetic, Although most commonly used in lung cancer investigation, EBUS is
most EBUS procedures today take place under conscious sedation and increasingly employed to diagnose other causes of mediastinal lymph
local anaesthetic. Using computed tomography (CT), with or without adenopathy and paramediastinal masses. Von Bartheld et al (2013)
positron emission tomography (PET) scanning, the areas that require carried out a randomized controlled trial demonstrating that EBUS or
sampling are identified. These lymph nodes or masses are then found EUSFNA was superior to combined endobronchial and transbronchial
during bronchoscopy using the ultrasound scanning probe. The infla biopsy (conventionally, the method of choice to obtain a tissue diag


tion of a small waterfilled balloon around the scanning probe can nosis in sarcoidosis) in the detection rate of noncaseating granulomas.
improve contact with the bronchial wall, and thus image quality, Sensitivity for the diagnosis of Mycobacterium tuberculosis has been
although in most cases it is not needed. A needle is inserted through reported at 85–94% (Sun et al 2013, Navani et al 2011), whilst for
the working channel of the bronchoscope and suction applied, via a lymphoma it may be as high as 89% and even higher for relapsed rather
syringe, at the proximal end of the needle. Under direct vision, the than de novo disease (Moonim et al 2013). Controversy remains about
needle is passed several times through the lesion in order to obtain a whether the cytological sample obtained at EBUS can give sufficient
cytological specimen. Suction is removed and the needle withdrawn information about lymphoma subtype compared to the larger samples
from the bronchoscope. The specimen is either smeared on to slides obtained by core or surgical biopsies that have been traditionally
and airdried, or placed into pots containing liquid preservative for favoured. At present, the British Thoracic Society feels that there is insuf
laboratory processing (Medford et al 2010). The power Doppler facility ficient evidence to justify the use of EBUSTBNA in lymphoma diagno
enables safer identification of vessels to avoid puncture of these sis (du Rand et al 2011) but this may change in the future as endoscopists
structures. and cytopathologists become more skilled. Using EBUS, the diagnosis
of metastatic extrathoracic malignancy (Ozgül et al 2013), chondrosar
Diagnosis and staging of lung cancer coma (Wang et al 2014), malignant pleural mesothelioma (Lococo et al
2014), vertebral body tumour (Ojha et al 2014), pulmonary artery
aneurysm (Lerner and Riker 2014), parathyroid adenoma (Buderi et al
The main use of EBUS in today’s clinical practice is in the diagnosis and
2014) and various other benign pathologies have all been reported in
staging of lung cancer. Surgical sampling of the mediastinum, whilst
the literature.


remaining the gold standard, has a number of limitations, including
invasiveness and cost. In 2009, a new lymph node map was published
Complications
by the International Association for the Study of Lung Cancer (Rusch
et al 2009). Using this as a guide, EBUS can access lymph node stations
2R, 2L, 3P, 4R, 4L, 7, 10R, 10L, 11R and 11L. When combined with A recent review of 190 studies published between 1995 and 2012,
endoscopic ultrasound (EUS), where an endoscope fitted with a linear comprising 16,181 patients, found a serious adverse event rate of 0.05%
ultrasound transducer is inserted into the oesophagus, additional sta for EBUS, increasing to 0.14% with the addition of figures for EUS (von
tions 8 and 9 can be sampled, as well as the left suprarenal gland, the Bartheld et al 2014). Abscess formation, sepsis, pneumothorax and
left lobe of the liver and the coeliac axis nodes, if necessary. Stations 5 other respiratory complications accounted for the EBUS adverse events,
and 6 can only be accessed via a surgical approach. whereas EUS had higher rates of infectious complications (including
Wallace et al (2008) showed, in 42 patients with malignant media mediastinitis), oesophageal perforation and haemorrhage. The results
stinal lymphadenopathy, that the sensitivity and negative predictive of the AQuIRE registry, published in 2013, reported a 1.44% complica
e70 value (NPV) of combined EBUS/EUSFNA were 93% and 97%, respec tion rate in 1,317 patients undergoing EBUS, including pneumothorax,


Endobronchial ultrasound
e71
2.7
YRATNEMMOC
bleeding, sustained hypoxia and respiratory failure (Eapen et al 2013); to yield greater amounts of tumour RNA when compared to the other
it is unclear how many of these cases also feature in the figures of the methods (although this only reached significance when compared to
aforementioned metaanalysis. Single case reports of needle breakage bronchoscopy). Certain genetic changes (particularly in the EGFR and
(Ozgül et al 2014) and pneumomediastinum/pneumopericardium ALK genes) may determine the chemotherapy agent of choice; a further
(Ortiz et al 2014) have also been published. However, the procedure is study has demonstrated that 52 of 55 samples obtained by EBUSTBNA
generally accepted to be safe. in patients with NSCLC contained sufficient material for fluorescent in
situ hybridization (FISH) analysis for ALK rearrangement or amplifica
The future
tion (Neat et al 2013). Yarmus et al (2013) found that four needle
passes (in conjunction with rapid onsite cytopathology evaluation)
In this era of increasingly personalized medicine, it is important for any yielded adequate amounts of tissue for EGFR and KRAS mutation analy
sampling technique to provide sufficient tissue for molecular analysis. sis on tumour DNA as well as ALK rearrangement testing by FISH
In a recent study of 106 patients with nonsmall cell lung cancer (Yarmus et al 2013).
(NSCLC), 101 samples taken at either standard bronchoscopy, EBUS The applications of EBUS continue to expand and with increased
TBNA or CTguided core biopsy were sufficient to yield RNA for further experience of both the operators and the cytopathologists examining
molecular testing (SchmidBindert et al 2013). EBUSTBNA was found the samples, the technique goes from strength to strength.
REFERENCES
Annema JT, van Meerbeeck JP, Rintoul RC et al 2010 Mediastinoscopy vs Ortiz R, Hayes M, Arias S et al 2014 Pneumomediastinum and pneumoperi
endosonography for mediastinal nodal staging of lung cancer: a rand cardium after endobronchial ultrasoundguided transbronchial needle


omized trial. JAMA 304:2245–52. aspiration. Ann Am Thorac Soc 11:680–1.
Buderi SI, Saleh HZ, Theologou T et al 2014 Endobronchial ultrasound Ozgül MA, Cetinkaya E, Tutar N et al 2013 Endobronchial ultrasound
guided biopsy to diagnose large posterior mediastinal parathyroid guided transbronchial needle aspiration for the diagnosis of intratho
adenoma prior to videoassisted thoracoscopic resection. BMJ Case Rep racic lymphadenopathy in patients with extrathoracic malignancy: a
May 13:2014. study in a tuberculosisendemic country. J Cancer Res Ther 9:416–21.
De Leyn P, Dooms C, Kuzdzal J et al 2014 Revised ESTS guidelines for preop Ozgül MA, Cetinkaya E, Tutar N et al 2014 An unusual complication of
erative mediastinal lymph node staging for nonsmallcell lung cancer. endobronchial ultrasoundguided transbronchial needle aspiration
Eur J Cardiothorac Surg 45:787–98. (EBUSTBNA): the needle breakage. Ann Thorac Cardiovasc Surg 20
Du Rand IA, Barber PV, Goldring J et al 2011 British Thoracic Society guide Supplement:567–9.
line for advanced diagnostic and therapeutic flexible bronchoscopy in Rusch VW, Asamura H, Watanabe H et al 2009 The IASLC lung cancer
adults. Thorax 66 Suppl 3:iii1–21. staging project: a proposal for a new international lymph node map in
Eapen GA, Shah AM, Lei X et al 2013 Complications, consequences, and the forthcoming seventh edition of the TNM classification for lung
practice patterns of endobronchial ultrasoundguided transbronchial cancer. J Thorac Oncol 4:568–77.
needle aspiration: results of the AQuIRE registry. Chest 143:1044–53. SchmidBindert G, Wang Y, Jiang H et al 2013 EBUSTBNA provides highest


Hürter T, Hanrath P 1992 Endobronchial sonography: feasibility and pre RNA yield for multiple biomarker testing from routinely obtained small
liminary results. Thorax 47:565–7. biopsies in nonsmall cell lung cancer patients – a comparative study
of three different minimal invasive sampling methods. PLoS One
Krasnik M, Vilmann P, Larsen SS et al 2003 Preliminary experience with a
8:e77948.
new method of endoscopic transbronchial real time ultrasound guided
biopsy for diagnosis of mediastinal and hilar lesions. Thorax 58: Sun J, Teng J, Yang H et al 2013 Endobronchial ultrasoundguided trans
1083–6. bronchial needle aspiration in diagnosing intrathoracic tuberculosis.
Ann Thorac Surg 96:2021–7.
Lee KJ, Suh GY, Chung MP et al 2014 Combined endobronchial and trans
esophageal approach of an ultrasound bronchoscope for mediastinal von Bartheld MB, Dekkers OM, Szlubowski A et al 2013 Endosonography
staging of lung cancer. PLoS One 9:e91893. vs conventional bronchoscopy for the diagnosis of sarcoidosis: the
GRANULOMA randomized clinical trial. JAMA 309:2457–64.
Lerner AD, Riker DR 2014 Use of endobronchial ultrasonography in the
diagnosis of a pulmonary artery aneurysm. Ann Thorac Surg 97: von Bartheld MB, van Breda A, Annema JT 2014 Complication rate of
e139–41. endosonography (endobronchial and endoscopic ultrasound): a sys
tematic review. Respiration 87:343–51.
Lococo F, Rossi G, Agostini L et al 2014 ‘Dry’ pleural mesothelioma success
fully diagnosed on endobronchial ultrasound (EBUS)guided trans Wallace MB, Pascual JM, Raimondo M et al 2008 Minimally invasive endo
bronchial needle aspiration (TBNA). Intern Med 53:467–9. scopic staging of suspected lung cancer. JAMA 299:540–6.


Medford AR, Bennett JA, Free CM et al 2010 Endobronchial ultrasound Wang KP, Terry P, Marsh B 1978 Bronchoscopic needle aspiration biopsy of
guided transbronchial needle aspiration (EBUSTBNA): applications in paratracheal tumors. Am Rev Respir Dis 118:17–21.
chest disease. Respirology 15:71–9. Wang R, Folch E, Paul M et al 2014 The use of CPEBUSTBNA in the diag
Moonim MT, Breen R, Fields PA et al 2013 Diagnosis and subtyping of de nosis of chondrosarcoma in a patient with Maffucci syndrome. J Bron
novo and relapsed mediastinal lymphomas by endobronchial ultra chology Interv Pulmonol 21:177–80.
sound needle aspiration. Am J Respir Crit Care Med 188:1216–23. Yarmus L, Akulian J, Gilbert C et al 2013 Optimizing endobronchial ultra
Navani N, Molyneaux PL, Breen RA et al 2011 Utility of endobronchial sound for molecular analysis. How many passes are needed? Ann Am
ultrasoundguided transbronchial needle aspiration in patients with Thorac Soc 10:636–43.
tuberculous intrathoracic lymphadenopathy: a multicentre study. Yasufuku K, Pierre A, Darling G et al 2011 A prospective controlled trial of
Thorax 66:889–93. endobronchial ultrasoundguided transbronchial needle aspiration
Neat MJ, Foot NJ, Hicks A et al 2013 ALK rearrangements in EBUSderived compared with mediastinoscopy for mediastinal lymph node staging of
transbronchial needle aspiration cytology in lung cancer. Cytopathology lung cancer. J Thorac Cardiovasc Surg 142:1393–400.e1.
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Ojha S, Ie S, Boyd M et al 2014 Vertebral body tumor biopsy: an expanded
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tion. J Bronchology Interv Pulmonol 21:85–7.


Abdomen and pelvis: overview and CHAPTER
59
surface anatomy
GENERAL STRUCTURE AND FUNCTION OF THE MUSCULOSKELETAL FRAMEWORK OF THE
ABDOMINOPELVIC CAVITY ABDOMEN AND PELVIS
Although often considered separately, the abdomen and pelvis form the The walls of the abdominopelvic cavity consist of five lumbar vertebrae
largest continuous visceral cavity of the body. Together, they provide and their intervening intervertebral discs (lying in the posterior midline);
multiple vital functions, including: housing and protection of the diges- the muscles of the anterior abdominal wall lying anteriorly (rectus
tive and urinary tracts and of the internal reproductive organs; a conduit abdominis) and anterolaterally (transversus abdominis, internal
for neurovascular communication between the thorax and lower limb; oblique and external oblique); the muscles of the posterior abdominal
support and attachment for the external genitalia; access to and from wall (psoas, quadratus lumborum and the diaphragm); the bony ‘basin’
the internal reproductive organs and urinary tract; assistance with formed by the walls of the false and true pelvis; the muscles of the pelvic
physio logical functions such as respiration, defecation and micturition; floor and perineum lying inferiorly; and the diaphragm lying superiorly
support for the vertebral column in weight-bearing, maintenance of (Fig. 59.1). In addition, the upper abdominal cavity gains protection
posture and movement; and, in women, the ability to support human from the lower six ribs and their cartilages, even though these structures
gestation. are technically part of the thoracic wall.
Fig . 59 .1 The bony and muscular structures making up
the abdominopelvic ‘cavity’ . The anterolateral abdominal
muscles have been removed for clarity .
Right cupola
(of diaphragm) Medial arcuate
ligament
Lateral arcuate
ligament
Right crus Tip of eleventh rib
Quadratus lumborum Tip of twelfth rib
Psoas minor
Iliac crest
Psoas major
Piriformis
Iliacus
Ischium
Obturator internus
Levator ani
1033


AbdOmEN ANd PElvIS: OvErvIEw ANd SurfACE ANATOmy
1034
8
NOITCES
The muscles of the abdominal wall play an important role in move- tion. Parasympathetic stimulation leads to opposing effects. Visceral
ment of the trunk (flexion, extension and rotation). The anterolateral afferents also pass through these autonomic plexuses.
muscles, in particular, provide assistance with rotation of the thorax in
relation to the pelvis (or vice versa if the thorax is fixed). Sympathetic innervation
The abdominal cavity is somewhat kidney-shaped in horizontal
cross-section due to the posterior indentation of the vertebral column. The cell bodies of neurones of the sympathetic supply of the abdomen
Consequently, there are two distinct paravertebral gutters on either and pelvis lie in the intermediolateral grey matter of the first to the
side of the spine. The lordosis of the lumbar spine combined with the twelfth thoracic and the first two lumbar spinal segments. Myelinated
backward angulation of the sacrum gives each paravertebral gutter a axons from these neurones travel in the ventral ramus of the spinal
parabola shape in sagittal section. In standing, the pelvic brim lies at nerve of the same segmental level, leaving it via a white ramus com-
an angle of about 55° to the horizontal such that the anterior supe- municans to enter a thoracic or lumbar paravertebral sympathetic gan-
rior iliac spines and pubic tubercles are in approximately the same glion. Visceral branches may exit at the same level or ascend or descend
coronal plane. The mean angle between the upper border of the first several levels in the sympathetic chain before exiting; they leave the
sacral vertebra and the horizontal plane is about 40–45° (Woon et al ganglia without synapsing and pass medially, giving rise to the paired
2013). greater, lesser and least splanchnic nerves, and the lumbar and sacral
splanchnic nerves. Axons destined to supply somatic structures synapse
Thoracoabdominal interface
in the sympathetic ganglion of the same level, and postganglionic,
unmyelinated axons leave the ganglion as one or more grey rami com-


The diaphragm constitutes the interface between the thoracic and municantes to enter the spinal nerve of the same segmental level.
abdominal cavities (Ch. 55). Three principal pathways exist between
Greater splanchnic nerve
the two cavities across the diaphragm: the caval opening in the central
tendon transmits the inferior vena cava and right phrenic nerve; the On each side, the greater splanchnic nerve is derived from the medial,
oesophageal hiatus, encircled by the right crus of the diaphragm, trans- visceral branches of the fifth to ninth thoracic sympathetic ganglia. It
mits the oesophagus, vagal trunks and vessels; and the aortic hiatus, gives off branches to the descending aorta and enters the abdomen
posterior to the median arcuate ligament of the diaphragm, transmits through the fibres of the ipsilateral crus of the diaphragm, on which it
the aorta, thoracic duct and, usually, the azygos vein. The hemiazygos descends anteroinferiorly. The main trunk of the nerve enters the supe-
vein usually enters the thorax through the left crus of the diaphragm. rior aspect of the coeliac ganglion, where most of the preganglionic
Other lymphatics from the abdomen drain to the thorax alongside the fibres synapse (but not those destined for the suprarenal medulla).
inferior vena cava and via small vessels passing through and around
lesser splanchnic nerve
the diaphragm. Thoracic splanchnic nerves reach the abdomen through
the diaphragmatic crura and behind the medial arcuate ligaments, On each side, the lesser splanchnic nerve is derived from the medial,
and the left phrenic nerve pierces the muscle of the left hemidiaphragm. visceral branches of the tenth and eleventh thoracic ganglia (or ninth
The subcostal vessels pass into the abdomen beneath the lateral arcuate and tenth). It enters the abdomen running through the lowermost fibres
ligaments of the diaphragm. Anteriorly, the superior epigastric vessels of the ipsilateral crus of the diaphragm or under the medial arcuate
pass between the costal and xiphoid attachments of the diaphragm. ligament, and then lies on the crus as it runs anteroinferiorly. The trunk


Neurovascular structures also cross between the thorax and abdomen of the nerve joins the aorticorenal ganglion and may give branches to
within the subcutaneous tissues. the lateral aspect of the coeliac ganglion. It occasionally joins the greater
and least splanchnic nerves as a single splanchnic nerve.
Pelvis–lower limb interface
least splanchnic nerve
On each side, the least splanchnic nerve is derived from the medial,
The pelvis forms an integral part of the bony structure of both the
visceral branches of the eleventh and/or twelfth thoracic ganglia. It
abdominopelvic cavity and the lower limb. It transmits the weight of
enters the abdomen medial to the sympathetic chain under the medial
the upright body, as well as providing a stable platform for movement
arcuate ligament of the diaphragm and runs inferiorly to join the renal
of the hip joint and bipedal locomotion. Its bony surfaces provide
plexus. The trunk of the nerve enters the aorticorenal ganglion and may
attachment sites for the muscles of the buttock and thigh (Ch. 80), the
give branches to the lateral aspect of the coeliac ganglion. It is some-
pelvic floor and perineal membrane, the abdominal wall and lower
times part of the lesser splanchnic nerve, when it forms a twig that
back. The pelvis also transmits the neurovascular structures that supply
enters the renal plexus just below the aorticorenal ganglion.
the lower limb. There are four principal pathways between the pelvis
The thoracic splanchnic nerves are subject to considerable individual
and lower limb: the interval beneath the inguinal ligament anterior to
variation in their origin and distribution (Loukas et al 2010). For
the superior pubic ramus and ilium, which transmits the femoral neu-
example, the greater splanchnic nerve may receive a contribution from
rovascular structures and lymphatics; the greater and lesser sciatic
the fourth or tenth thoracic sympathetic ganglia or originate only from
foramina, which transmit the gluteal vessels and nerves, sciatic nerve,
the sixth to ninth ganglia.
and internal pudendal vessels and pudendal nerve; and the obturator
foramen, which transmits the obturator nerve, vessels and lymphatics. lumbar sympathetic system


Autonomic nerves travel with the arterial supply to the lower limb and
The lumbar part of each sympathetic trunk usually contains four inter-
with the branches of the sacral plexus. Neurovascular structures also
connected ganglia lying on the anterolateral aspects of the lumbar
cross between the lower limb and pelvis within the subcutaneous
vertebrae along the medial margin of psoas major (see Figs 59.2, 62.14)
tissues.
(Murata et al 2003). Superiorly, it is continuous with the thoracic sym-
pathetic trunk posterior to the medial arcuate ligament. Inferiorly, it
passes posterior to the common iliac vessels and is continuous with the GENERAL ARRANGEMENT OF ABDOMINOPELVIC
sacral sympathetic trunk. On the right side, it lies posterior to the infe-
AUTONOMIC NERVES
rior vena cava; on the left, it is posterior to the lateral aortic lymph
nodes. It is anterior to most of the lumbar vessels but may pass behind
What follows is a brief overview of the autonomic nervous system in some lumbar veins.
the abdominopelvic region; descriptions of the neurovascular supply to On each side, the first, second and, sometimes, the third lumbar
individual organs are given in the relevant chapters. The autonomic ventral spinal rami are connected to the lumbar sympathetic trunk by
supply to the abdominal and pelvic viscera is via the abdominopelvic white rami communicantes. All lumbar ventral rami are joined near
part of the sympathetic chain and the greater, lesser and least splanchnic their origins by long, slender, grey rami communicantes from the four
nerves (sympathetic), and the vagus and pelvic splanchnic nerves (para- lumbar sympathetic ganglia. Their arrangement is irregular: one gan-
sympathetic). Numerous interconnections occur between plexuses and glion may give rami to two or three lumbar ventral rami, one lumbar
ganglia, particularly in the major plexuses around the abdominal aorta; ventral ramus may receive rami from two ganglia, or grey rami may
hence, the descriptions tend to be simplifications based on the ‘main’ leave the sympathetic trunk between ganglia (Murata et al 2003).
supply to each organ (Fig. 59.2). The details of the terminations of


these fibres are given in the description of the microstructure of the gut Somatic and vascular branches
wall. Sympathetic nerve branches accompany the lumbar arteries round the
As a general rule, sympathetic neurones from the abdominopelvic sides of the vertebral bodies, medial to the fibrous arches to which psoas
autonomic plexuses inhibit visceral smooth muscle motility and glan- major is attached, to provide sympathetic innervation to the lumbar
dular secretions, induce sphincter contraction and cause vasoconstric- somatomes. Branches from the lumbar ganglia innervate the abdominal


General arrangement of abdominopelvic autonomic nerves
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Fig . 59 .2 The overall arrangement of the autonomic
plexuses of the abdominal and pelvic viscera .
Anterior and
posterior
vagal trunks
Superior
mesenteric Coelic plexus and ganglia
plexus and ganglia
T12 sympathetic
ganglion Left aorticorenal plexus
and ganglion
Right renal ganglion
and plexus
Intermesenteric
L1–4 sympathetic plexuses
ganglia
Inferior mesenteric
plexus and ganglia
Right lumbar
Superior hypogastric
sympathetic chain
plexus
Hypogastric nerve
Inferior hypogastric
plexus
aorta and common, external and internal iliac arteries, forming delicate Damage to these nerves, e.g. during aortoiliac surgery, can result in
nerve plexuses that extend along the vessels. Other postganglionic sym- sexual dysfunction.
pathetic nerves to vessels and skin travel with somatic nerves. Thus, the
femoral nerve carries vasoconstrictor sympathetic nerves to the femoral Pelvic sympathetic system
artery and its branches in the thigh, as well as sympathetic fibres in its The sacral region of the sympathetic trunk usually consists of four or
cutaneous branches. Postganglionic fibres travelling with the obturator five ganglia located medial or anterior to the anterior sacral foramina
nerve supply the obturator artery and the skin of the medial thigh. beneath the presacral fascia (Oh et al 2004). Occasionally, one or two
Sympathetic denervation of vessels in the lower limb can be effected by coccygeal ganglia are present. The sacral sympathetic trunk is continu-
removing or ablating the upper three lumbar ganglia and intervening ous above with the lumbar sympathetic trunk, and preganglionic fibres
parts of the sympathetic trunk; this procedure may be useful in treating descend from the lower lumbar spinal cord segments via this route. The
some varieties of vascular insufficiency of the lower limb. first sacral sympathetic ganglion is the largest. More caudal ganglia
become progressively smaller (Blaszczyk 1981). The sacral sympathetic
Lumbar splanchnic nerves chain is often asymmetric, with absent or fused ganglia, and cross-


Four lumbar splanchnic nerves pass as medial branches from the communications between each side are frequent. Each ganglion sends
ganglia to join the coeliac, inferior mesenteric and superior hypogastric at least one grey ramus communicans to its adjacent spinal nerve
plexuses. The first lumbar splanchnic nerve, from the first ganglion, but up to 11 such branches from a single ganglion have been reported
gives branches to the coeliac, renal and inferior mesenteric plexuses. (Potts 1925).
The second nerve joins the inferior part of the intermesenteric or infe- The pelvic sympathetic chain converges caudally to form a
rior mesenteric plexus. The third nerve arises from the third or fourth solitary retroperitoneal structure, the ganglion impar (or ganglion of
ganglion and joins the superior hypogastric plexus. The fourth lumbar Walther), which lies at a variable level between the sacrococcygeal
splanchnic nerve from the lowest ganglion passes anterior to the joint and the tip of the coccyx; it is occasionally paired, unilateral
common iliac vessels to join the lower part of the superior hypogastric or absent (Oh et al 2004). It conveys sympathetic efferents to and
plexus, or the hypogastric nerves. It is important to note that lumbar nociceptive afferents from the perineum and terminal urogenital
splanchnic sympathetic nerves contribute to the superior and inferior regions. Ganglion impar blockade may be used to treat intractable
hypogastric plexuses and, therefore, contribute to the innervation of the perineal pain of sympathetic origin in patients with pelvic cancers
bladder neck, ductus deferens and prostate, among other structures. (Toshniwal 2007).


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Somatic and vascular branches gastric branch, and run beneath the peritoneum, deep to the posterior
Grey rami communicantes containing postganglionic sympathetic wall of the upper part of the lesser sac, to reach the coeliac plexus. Their
nerves pass from the pelvic sympathetic ganglia to the sacral and coc- synaptic relays with postganglionic neurones are situated in the mye-
cygeal spinal nerves. There are no white rami communicantes at this nteric (Auerbach’s) and submucosal (Meissner’s) plexuses in the wall
level. The postganglionic fibres are distributed via the sacral and coc- of the gut (see below).
cygeal plexuses (Woon and Stringer 2014). Thus, sympathetic fibres in
Pelvic splanchnic nerves
the tibial nerve are conveyed to the popliteal artery and its branches in
the leg and foot, whilst those in the pudendal and superior and inferior Pelvic splanchnic nerves to the pelvic viscera travel in the anterior rami
gluteal nerves accompany these arteries to the perineum and buttocks. of the second, third and fourth sacral spinal nerves. They leave the
Small branches also travel with the median and lateral sacral arteries. nerves as they exit the anterior sacral foramina and pass in the presacral
tissue as a fine network of branches that are distributed to three prin-
Sacral splanchnic nerves cipal destinations. Most pass anterolaterally into the network of nerves
Sacral splanchnic nerves pass directly from the ganglia to the inferior that form the inferior hypogastric plexus; from here, they pass to the
hypogastric plexus and, from there, to pelvic viscera; they usually arise pelvic viscera. Some join directly with the hypogastric nerves and ascend
from the first two sacral sympathetic ganglia. out of the pelvis, as far as the superior hypogastric plexus; from here,
they are distributed with branches of the inferior mesenteric artery
Parasympathetic innervation (p. 1153). A few run superolaterally in the presacral tissue, over the


pelvic brim anterior to the left iliac vessels, and pass directly into the
tissue of the retroperitoneum and the mesentery of the sigmoid and
The parasympathetic neurones innervating the abdomen and pelvis lie
descending colon.
either in the dorsal motor nucleus of the vagus nerve or in the interme-
The pelvic splanchnic nerves are motor to the smooth muscle of the
diolateral grey matter of the second, third and fourth sacral spinal
hindgut and bladder wall, supply vasodilator fibres to the erectile tissue
segments. The vagus nerves supply parasympathetic innervation to the
of the penis and clitoris, and are secretomotor to the hindgut.
abdominal viscera as far as the distal transverse colon, i.e. they supply
the foregut and midgut. The hindgut is supplied by parasympathetic
Abdominopelvic autonomic plexuses
fibres travelling via the pelvic splanchnic nerves (see below); the overlap
and ganglia
between these two supplies is variable. The vagal trunks are derived
from the oesophageal plexus and enter the abdomen via the oesopha-
geal hiatus, closely related to the anterior and posterior walls of the The abdominopelvic autonomic plexuses are somewhat variable and
abdominal oesophagus (see Fig. 56.6). The anterior vagal trunk is often fuse or are closely interrelated. The following descriptions recog-
mostly derived from the left vagus and the posterior from the right nize their main features (Figs 59.3–59.4).
vagus. The nerves supply the intra-abdominal oesophagus and stomach
Coeliac plexus
directly. The anterior trunk gives off a hepatic branch, which innervates
the liver parenchyma and vasculature, the biliary tree including the The coeliac plexus is located at the level of the twelfth thoracic and first
gallbladder, and the structures in the free edge of the lesser omentum. lumbar vertebrae, and is the largest major autonomic plexus. It is a
The posterior trunk supplies branches to the coeliac plexus; these fibres dense network that unites the coeliac ganglia, and surrounds the coeliac
frequently constitute the largest portion of the fibres contributing to the artery and the root of the superior mesenteric artery. It is posterior to


plexus. They arise directly from the posterior vagal trunk and from its the stomach and lesser sac, and anterior to the crura of the diaphragm
Sympathetic Parasympathetic
Greater splanchnic nerve (T5–9) Posterior vagal trunk
T12
Lesser splanchnic nerve (T10,11)
Coeliac plexus
T12g
L1
Superior mesenteric plexus
L1g
Intermesenteric plexus
L2
First lumbar sympathetic nerve
L2g Inferior mesenteric plexus
Second lumbar sympathetic nerve
Lumbar splanchnic nerves L3 Superior hypogastric plexus
L3g
Third lumbar sympathetic nerve
L4 Retroperitoneal parasympathetic fibres
Fourth lumbar sympathetic nerve
L4g
Inferior hypogastric nerve
Inferior hypogastric plexus
S1g
Sacral splanchnic nerves
Pelvic splanchnic nerves
S2g
Key
S2
T12g – 12th thoracic sympathetic ganglion S1g – 1st sacral sympathetic ganglion S3g Nervous structures
L1g – 1st lumbar sympathetic ganglion S2g – 2nd sacral sympathetic ganglion S3 Sympathetic fibres
Parasympathetic fibres
L2g – 2nd lumbar sympathetic ganglion S3g – 3rd sacral sympathetic ganglion S4g S4 Ganglion
L3g – 3rd lumbar sympathetic ganglion S4g – 4th sacral sympathetic ganglion Plexus tissue
L4g – 4th lumbar sympathetic ganglion Nerve fibres
Fig . 59 .3 The autonomic plexuses innervating the abdominal and pelvic viscera: schematic diagram .


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Fig . 59 .4 The autonomic
Branches of posterior vagal trunk
plexuses of the abdominal
Greater splanchnic nerve
and pelvic viscera .
Lesser splanchnic nerve
Coeliac plexus and ganglia
Middle colic artery Superior mesenteric plexus and ganglion
Left renal vein
First and second lumbar nerves
Intermesenteric plexus
Right colic artery
Inferior mesenteric plexus and ganglion
Left ureter
Third and fourth lumbar nerves
Sigmoid branches of inferior mesenteric artery
Lumbar sympathetic chain Retroperitoneal parasympathetic fibres
External iliac artery
Internal iliac artery
Inferior hypogastric plexus
Inferior hypogastric plexus
Sacral sympathetic chain
Sacral parasympathetic roots
Communication with Fig . 59 .5 Distribution of
phrenic plexus the upper abdominal
autonomic plexuses .
Right coeliac ganglion
Right aorticorenal ganglion Coeliac plexus
Right suprarenal gland
Left greater
splanchnic nerve
Left lesser
splanchnic nerve
Right kidney
Superior
mesenteric
plexus
Left renal plexus
Intermesenteric plexus
Aorta
and the beginning of the abdominal aorta, and lies medial to the supra- Anaesthesia or ablation of these nerves (coeliac plexus block) is some-
renal glands. The plexus and ganglia receive the greater and lesser times undertaken to treat intractable pain from pancreatic disorders.
splanchnic nerves and branches from the vagal trunks. The plexus is in
continuity with small branches along adjacent arteries and is connected Coeliac and aorticorenal ganglia
to the phrenic, splenic, hepatic, superior mesenteric, suprarenal, renal The coeliac ganglia are irregular neural masses, measuring approxi-
and gonadal plexuses (Fig. 59.5). Visceral afferents in the coeliac plexus mately 2 cm across, located between the origin of the coeliac trunk and
convey pain and other sensations from upper abdominal viscera. superior mesenteric artery, medial to the suprarenal glands and anterior


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NOITCES
to the crura of the diaphragm (Zhang et al 2006). They vary in number, internal iliac vessels and the attachments of levator ani and obturator
size, shape and precise location; there are often two, one on each side. internus lie laterally, and the superior vesical and obliterated umbilical
The right ganglion is frequently posterior to the inferior vena cava, and arteries superiorly. In males, the inferior hypogastric plexus lies postero-
the left ganglion often lies posterior to the origin of the splenic artery. laterally on either side of the seminal vesicles, prostate and the base of
The ipsilateral greater splanchnic nerve joins the upper part of each the urinary bladder. In men, the point where the vas (ductus) deferens
ganglion and the lesser splanchnic nerve joins the lower part. The lower- crosses the ureter provides an approximate guide to the upper limit of
most part of each ganglion forms a distinct subdivision, usually termed the plexus (Mauroy et al 2003). The upper border of the plexus lies
the aorticorenal ganglion, which receives the ipsilateral lesser splanch- beneath the peritoneum of the rectovesical pouch and is in contact
nic nerve and gives origin to the majority of the renal plexus (which, with the lateral aspect of the base of the bladder. The anterior border
most commonly, lies anterior to the origin of the renal artery). reaches the posterior aspect of the prostate; at its inferior limit, the
cavernous (deep, cavernosal) nerve passes forwards to reach the postero-
Phrenic plexus lateral aspect of the prostate (see Fig. 75.11). In females, each plexus
The phrenic plexus is a periarterial extension of the coeliac plexus lies lateral to the uterine cervix, vaginal fornix and the posterior part of
around the right inferior phrenic artery, adjacent to the right crus of the the urinary bladder, often extending into the broad ligaments of the
diaphragm (Rusu 2006). It contains one or two phrenic ganglia and a uterus. The upper limit of the plexus corresponds approximately to the


definable nerve trunk that connects the coeliac plexus and phrenic level where the uterine artery crosses the ureter in the base of the broad
nerve. The plexus supplies branches to the suprarenal glands and ligament (Azaïs et al 2013).
diaphragm. The inferior hypogastric plexus is formed mainly from pelvic
splanchnic (parasympathetic) and sacral splanchnic (sympathetic)
Superior mesenteric plexus and ganglion
branches; a smaller contribution is derived from sympathetic fibres
The superior mesenteric plexus lies in the pre-aortic connective tissue (from the lower lumbar ganglia), which descend into the plexus from
posterior to the pancreas, around the origin of the superior mesenteric the superior hypogastric plexus via the hypogastric nerves. It gives origin
artery. It is an inferior continuation of the coeliac plexus, and includes to a complex network of small pelvic branches, which supply the pelvic
branches from the posterior vagal trunk and coeliac plexus. Its branches viscera either directly or indirectly via periarterial plexuses. The branches
accompany the superior mesenteric artery and its divisions. The supe- of the inferior hypogastric plexus supply the vas deferens, seminal vesi-
rior mesenteric ganglion lies superiorly in the plexus, usually above the cles, prostate, accessory glands and penis in males; the ovary, Fallopian
origin of the superior mesenteric artery. tubes, uterus, uterine cervix and vagina in females; and the urinary
bladder and distal ureter in both sexes. The plexus plays a key role in
Intermesenteric plexus
continence and sexual function.
Like other parts of the abdominal aortic autonomic plexus, the interme-
senteric plexus is not a discrete structure but is part of a continuous Hypogastric nerves The hypogastric nerves are usually paired nerve
periarterial nerve plexus connected to the gonadal, inferior mesenteric, bundles but may consist instead of multiple filaments. They contain
iliac and superior hypogastric plexuses. It lies on the lateral and anterior sympathetic fibres (mostly descending from the superior hypogastric


aspects of the aorta, between the origins of the superior and inferior plexus) and parasympathetic fibres (ascending from the inferior
mesenteric arteries, and consists of numerous fine, interconnected nerve hypogastric plexus). The nerves run between the superior and inferior
fibres and a few ganglia continuous superiorly with the superior hypogastric plexuses on each side behind the presacral fascia medial to
mesenteric plexus and inferiorly with the superior hypogastric plexus. the internal iliac vessels and lateral to the anterior sacral foramina.
It is not well characterized but receives parasympathetic and sympa-
thetic branches from the coeliac plexus and additional sympathetic Other autonomic plexuses and ganglia
rami from the first and second lumbar splanchnic nerves. Additional plexuses are described for abdominopelvic viscera, such as
the hepatic and gonadal plexuses. Each tends to lie around the main
Inferior mesenteric plexus
arterial supply to the organ. They receive both sympathetic and para-
The inferior mesenteric plexus lies around the origin of the inferior sympathetic fibres from one or more of the major autonomic plexuses
mesenteric artery and is distributed along its branches. It is formed and have one or more ganglia. Thus, autonomic ganglia supplying the
predominantly from the aortic plexus, supplemented by sympathetic testis are found around the origin of the testicular arteries from the
fibres from the first and second lumbar splanchnic nerves and ascend- abdominal aorta and have connections with the renal, lumbar and
ing pelvic parasympathetic fibres from the inferior hypogastric plexus intermesenteric autonomic plexuses (Motoc et al 2010).
(via the hypogastric nerves and superior hypogastric plexus). Disrup-
tion of the inferior mesenteric plexus alone rarely causes clinically
Para-aortic bodies
significant disturbances of autonomic function.
Superior hypogastric plexus The para-aortic bodies (also known as paraganglia or, collectively, as
The superior hypogastric plexus lies anterior to the aortic bifurcation, the organ of Zuckerkandl) are collections of neural crest-derived chro-


the left common iliac vein, median sacral vessels, fifth lumbar vertebral maffin tissue found in close relation to the aortic autonomic plexuses.
body and sacral promontory, and between the common iliac arteries. They are relatively large in the fetus, reach a maximum size at around
It is occasionally referred to as the presacral nerve, but is seldom a single 3 years of age, and have usually regressed by adulthood. They are most
nerve and is prelumbar rather than presacral. It lies within extraperito- commonly found as a pair of bodies lying anterolateral to the aorta in
neal connective tissue in the midline, extending a little to the left. The the region of the inferior mesenteric and superior hypogastric plexuses,
breadth of the plexus and its constituent nerves varies; appearances but multiple smaller collections may be present. Occasionally, they are
range from a reticular-like arrangement to a band-like structure or one found as high as the coeliac plexus or as low as the inferior hypogastric
or two distinct nerve trunks (Paraskevas et al 2008). The medial attach- plexus in the pelvis, or may be closely applied to the sympathetic
ment of the sigmoid mesocolon and upper limit of the mesorectum lie ganglia of the lumbar chain. Scattered cells that persist into adulthood
anterior to the lower part of the plexus, separated from it by a thin layer may, rarely, be the sites of paraganglioma (extra-adrenal phaeochromo-
of loose connective tissue. The plexus is formed by branches from three cytoma) (Subramanian and Maker 2006).
main sources: the aortic plexus (sympathetic and parasympathetic),
lumbar splanchnic nerves (sympathetic) and pelvic splanchnic nerves
GENERAL ARRANGEMENT OF ABDOMINOPELVIC
(parasympathetic), which ascend from the inferior hypogastric plexus
via the right and left hypogastric nerves. Visceral afferents also pass VASCULAR SUPPLY
through the plexus. The hypogastric nerves lie in loose connective tissue
just posterolateral to the upper mesorectum and pass over the pelvic The major vessels that occupy the abdomen and pelvis not only supply


brim medial to the internal iliac vessels. The superior hypogastric plexus the viscera, retroperitoneal structures and much of the bony and soft
conveys branches to the inferior mesenteric plexus and to the ureteric, tissue walls of both cavities, but also course through the cavities en route
gonadal and common iliac nerve plexuses; additional small branches to supply the lower limbs. The arteries and systemic veins of the
turn abruptly forwards into the upper mesorectum to travel with the abdomen and pelvis lie predominantly posteriorly in the abdomen and
superior rectal artery. posterolaterally in the pelvis. From the caval and aortic openings in the
diaphragm, they follow the general parabolic shape of the lumbar
Inferior hypogastric plexus spine. The pelvic divisions follow the contours of the brim and side
The inferior hypogastric plexus lies in the thin extraperitoneal connec- wall of the true pelvis (Figs 59.6–59.7). The individual parts of the
tive tissue on the pelvic side wall anterolateral to the mesorectum. The aortoiliac and iliocaval systems are described in the relevant chapters.


General arrangement of abdominopelvic autonomic nerves
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Fig . 59 .6 The overall arrangement of the aortoiliac arterial
tree of the abdomen and pelvis .
Left inferior
phrenic artery
Coeliac trunk
Right suprarenal Left renal artery
artery
Superior
Abdominal aorta mesenteric artery
Left gonadal artery
Right second, third and fourth
lumbar arteries
Inferior
mesenteric artery
Right common
iliac artery
Right iliolumbar Left internal
artery iliac artery
Right external
iliac artery
Arterial supply to the gastrointestinal tract (Ch. 69). Anastomoses between the territories of the superior and infe-
rior mesenteric arteries are less numerous; the most consistent is the
marginal artery of the colon (Ch. 66).
The arterial supply to the gastrointestinal tract is derived from the ante-
rior midline visceral branches of the aorta. There are usually three
Portal venous system
anterior branches: the coeliac trunk and the superior and inferior
mesenteric arteries. Major variants in the origin of the arteries are
uncommon (Ch. 62). Accessory or replaced branches to the abdominal The (hepatic) portal system, like all portal venous systems, connects two
viscera are more common. The inferior mesenteric artery almost always capillary beds: that of the abdominal and pelvic parts of the gut from
arises separately but replaced, accessory or anastomotic vessels may the abdominal part of the oesophagus to the lower anal canal, together
arise from the proximal superior mesenteric artery or its branches. with all derived organs other than the liver (i.e. the pancreas, gallblad-
Occasionally, these may contribute to the arterial supply of the inferior der and spleen), and the hepatic sinusoidal ‘capillary’ bed. The intra-
mesenteric artery (Horton and Fishman 2002). hepatic portal vein ramifies and ends in the hepatic sinusoids; from
The coeliac trunk and its branches supply the part of the foregut that here, blood drains to central veins that converge to form the hepatic
extends from the distal oesophagus to the mid part of the descending veins which drain into the inferior vena cava (Ch. 67). In adults, the


duodenum, together with associated viscera (liver, biliary tree, spleen, portal vein has no valves. In fetal and early postnatal life, valves are
dorsal pancreas, greater and lesser omenta). The superior mesenteric demonstrable in tributaries of the portal vein but they usually atrophy
artery supplies the midgut, which extends from the mid descending with further maturation.
duodenum to the distal third of the transverse colon (including
Portal vein
jejunum, ileum, caecum, appendix, ascending and transverse colon).
The inferior mesenteric artery supplies the part of the hindgut that The portal vein is formed behind the neck of the pancreas at the level
extends from the distal transverse colon to the upper anal canal. Even of the L1/2 intervertebral disc (in the transpyloric plane) from the
in the absence of accessory arteries, numerous anastomoses exist convergence of the superior mesenteric and splenic veins (Fig. 59.8). It
between these vascular territories. For example, anastomoses around the is approximately 8 cm long in the adult and ascends obliquely to the
head of the pancreas and the duodenum are formed between the ante- right behind the first part of the duodenum, the common bile duct and
rior and posterior superior pancreaticoduodenal arteries and the ante- gastroduodenal artery; at this point, it is directly anterior to the inferior
rior and posterior inferior pancreaticoduodenal arteries, and between vena cava. It enters the right border of the lesser omentum and ascends
the posterior superior pancreaticoduodenal artery and jejunal arteries anterior to the epiploic foramen to reach the right end of the porta


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Fig . 59 .7 The overall arrangement of the iliocaval venous
system of the abdomen and pelvis .
Inferior
vena cava
Hemiazygos vein
Left suprarenal vein
Right subcostal
Left renal vein
vein
Left gonadal vein
Right first
lumbar vein
Left lumbar veins
Right ascending
lumbar vein
Right
gonadal vein
Right iliolumbar
Left internal
vein
iliac vein
Right common
iliac vein Left external iliac vein
hepatis, where it divides into right and left main branches, which the hindgut traverses the pelvic floor; in these sites, the gut tube is sur-
accompany the corresponding branches of the hepatic artery into the rounded by a connective tissue adventitia. Neural elements invade the
liver. In the lesser omentum, the portal vein lies posterior to both the gut from neural crest tissue (Ch. 17). The smooth muscle of the mus-
common bile duct and the hepatic artery. It is surrounded by the hepatic cularis externa layers of the alimentary canal is supplemented with
nerve plexus and accompanied by lymphatics and some lymph nodes. striated muscle at the beginning (from the branchial arches) and end
of the gut tube.
Tributaries of the portal vein The mature gut wall has four main layers: mucosa, submucosa,
The main extrahepatic tributaries of the portal vein are the left gastric muscularis externa and serosa (Fig. 59.9). The mucosa (mucous mem-
(coronary) vein and the posterior superior pancreaticoduodenal vein brane) is the innermost layer and is subdivided into a lining epithelium,
(Ch. 67). Within the liver, the left branch receives the obliterated an underlying lamina propria (a layer of loose connective tissue, where
umbilical vein via the ligamentum teres, which connects to its vertical many of the glands are also found) and a thin layer of smooth muscle,
portion. the muscularis mucosae. The submucosa is a strong and highly vascular-
ized layer of connective tissue. The muscularis externa consists of inner
circular and outer longitudinal layers of smooth muscle; an incomplete


GENERAL MICROSTRUCTURE OF THE GUT WALL
oblique muscle layer is present only in the stomach. The external
surface is bounded by a serosa or adventitia, depending on its position
The gut wall displays a common structural plan that is modified region- within the body.
ally to take account of local functional differences. The general micro-
structure is best appreciated by reference to the development of the gut
Mucosa
(Ch. 60). Much of the alimentary canal originates as a tube of endo-
derm enclosed in splanchnopleuric mesoderm. Its external surface faces
the embryonic coelom, and the endodermal lining forms the epithe- Epithelium
lium of the canal and also the secretory and ductal cells of various The epithelium is the site of secretion and absorption, and provides a
glands that secrete into the lumen, including the pancreas and liver. The defence against various threats, including microorganisms. Its protec-
splanchnopleuric mesoderm forms the connective tissue, muscle layers, tive function against mechanical, thermal and chemical injury is par-
blood vessels and lymphatics of the wall, and its external surface ticularly evident in the oesophagus and anal canal, where it is thick,
becomes the visceral mesothelium or serosa. There is no serosa sur- stratified and covered in mucus, which serves as a protective lubricant.
rounding the cervical and thoracic portions of the gut, or below where At other sites, the epithelium lining the gut wall is single-layered, and


General microstructure of the gut wall
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Fig . 59 .8 The overall arrangement of the portal
venous system draining the abdominal viscera .
Inferior
vena cava Short gastric veins
Portal vein
Splenic vein
Pancreatico-
Left gastroepiploic vein
duodenal veins
Superior
mesenteric vein
Inferior mesenteric vein
Middle colic vein
Left colic vein
Marginal colic veins
Ileocolic vein
Sigmoid veins
Superior rectal vein
either cuboidal (in glands) or columnar. It contains cells modified for mucosae are found inside the villi or between the tubular glands of the
absorption, as well as various types of secretory cell. stomach and large intestine. By its contraction, the muscularis mucosae
The barrier function and selectivity of absorption depend on tight can alter the surface configuration of the mucosa locally, allowing it to
junctions over the entire epithelium. The surface area of the lumen adapt to the shapes and mechanical forces imposed by the contents of
available for secretion or absorption is increased by the presence of the lumen, and in the intestinal villi, promoting vascular exchange and
mucosal folds, crypts, villi and glands (see Fig. 59.9). Microvilli on the lymphatic drainage.
surfaces of individual absorptive cells amplify the area of apical plasma
membrane in contact with the contents of the gut. Some glands lie in Submucosa
the lamina propria and some in the submucosa; others (the liver and
pancreas) are totally external to the wall of the gut. All of these glands
The submucosa contains large bundles of collagen and is the strongest
drain into the lumen of the gut through individual ducts. The epithe-
layer of the gut wall. However, it is also pliable and deformable, and
lium also contains scattered neuroendocrine (enteroendocrine) cells.
can therefore adjust to changes in the length and diameter of the gut.
Lamina propria Its contained arterial network is relatively dense and supplies both the
mucosa and the muscle coat. The submucosa extends into the rugae of
The lamina propria consists of compact connective tissue, often rich in


the gastric wall, the plicae circulares of the small intestine (but not the
elastin fibres, which supports the surface epithelium and contains nutri-
villi), and the folds that project into the lumen of the colon and rectum.
ent vessels and lymphatics. Lymphoid follicles are present in many
regions of the gut, most notably in Peyer’s patches. Cells within the
Muscularis externa
lamina propria are the source of growth factors that regulate cell turn-
over, differentiation and repair in the overlying epithelium.
The muscularis externa usually consists of distinct inner circular and
Muscularis mucosae outer longitudinal layers that create waves of peristalsis responsible for
The muscularis mucosae is particularly well developed in the oesopha- the movement of ingested material through the lumen of the gut. In
gus and in the large intestine, especially in the terminal part of the the stomach, where movements are more complex, there is an incom-
rectum. In addition, single muscle cells originating from the muscularis plete oblique layer of muscle, internal to the other two layers. The


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NOITCES
Layers of the gut wall
A. Mucosa
B. Submucosa
C. Muscularis externa
D. Serosa
Epithelium
A
Lamina propria
Muscularis
mucosae
B Submucosa
Inner Colon
circular
layer
Ileum
C
Jejunum
Outer
longitudinal Duodenum
layer
Stomach
Secretions
Oesophagus of liver and
D Serosa pancreas
Fig . 59 .9 The general arrangement of the alimentary canal to show the layers of the gut wall at the levels indicated .
circular muscle layer is invariably thicker than the longitudinal muscle, stomach, or partitions them, as occurs at the pyloric sphincter. The
except in the colon, where the longitudinal muscle is condensed into muscle maintains a constant volume, so that shortening of a segment
three cords (taenia coli). of the gut wall is accompanied by an increase in thickness of the
The muscularis externa is composed almost exclusively of smooth muscle layer.
muscle, except in the upper oesophagus, where smooth muscle blends Intestinal smooth muscle exhibits variable and changing degrees of
with striated muscle. Although the upper oesophageal musculature contraction on which rhythmic (or phasic) contractions are superim-
resembles that of the pharynx, it is entirely under involuntary control. posed. Slow waves of rhythmic electrical activity, driven by changes in
For most of its length, the smooth muscle of the gut wall consists of membrane potentials in pacemaker cells (interstitial cells), spread
ill-defined bundles of cells, typically visceral in type, and somewhat throughout the thickness of the circular and longitudinal smooth
larger than vascular smooth muscle cells. They are approximately muscle coats. After spreading circumferentially, slow waves can move
500 µm long, regardless of body size, and are electrically and mechani- in either oral or anal directions, causing segmental contraction. The
cally coupled. Their fasciculi lack a perimysium but have sharp distances of propagation and the patterns of this spontaneous activity
boundaries. vary between areas of the intestine. Neural regulation of slow and
The arrangement of the musculature allows a segment of gut to phasic contractions involves excitatory and inhibitory transmitters that


undergo extensive changes in diameter (to virtual occlusion of the are released from the myenteric plexus. This motor control is closely
lumen) and length, although elongation is limited by the presence of coordinated with mucosal absorption and secretion, and is mediated
mesenteries. The coordinated activity of the two muscle layers pro- via intrinsic nerves in the submucous plexus. The peristaltic reflex
duces a characteristic motor behaviour that is mainly propulsive and occurs during passage of luminal contents down the intestine. It
directed aborally (peristalsis), combined with a non-propulsive motor involves ascending contraction and descending relaxation; the sensory
activity that either mixes the luminal contents, as occurs in the limb is mediated by sensory neurones that respond to either mucosal


General microstructure of the gut wall
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stimulation (intrinsic primary afferents) or muscle stretch (extrinsic The latter is not essential for function, as evidenced by intestinal activity
afferents). after transplantation of the extrinsically denervated gut. In contrast,
neuropathies affecting the enteric nervous system, such as Hirsch-
Interstitial cells
sprung’s disease, are potentially life-threatening. For a detailed descrip-
Interstitial cells of Cajal (ICCs) are found throughout the entire length tion of the enteric nervous system, see Furness et al (2014).
of the gastrointestinal tract, where they lie in close contact with nerve
terminals; they have numerous gap junctions with each other and with Extrinsic innervation
smooth muscle cells. Distinct networks are found in the myenteric
Extrinsic innervation of the gut is from sympathetic, parasympathetic
plexus between the circular and longitudinal muscle. Looser arrange-
and visceral sensory nerves. The cell bodies of preganglionic parasym-
ments exist within the individual muscle layers and the submucosa of
pathetic efferent axons are found in the vagal dorsal motor nucleus in
the gut, and isolated or small groups of ICCs are also found in the
the medulla oblongata and in the sacral segments of the spinal cord.
subserosal region. ICCs originate from mesenchymal cells and resemble
Their main target in the gut is the enteric neurones of the myenteric
smooth muscle cells but have fewer contractile elements and their
plexus. Vagal efferents play a major role in oesophageal propulsion,
intermediate filaments contain vimentin rather than desmin. They are
gastric acid secretion and emptying, gallbladder contraction and pan-
involved in the generation of pacemaker signals, the propagation of
creatic exocrine secretion. Pelvic efferents innervate the distal colon and
electrical slow wave activity, neuromuscular transmission, and mech-
rectum. Sympathetic efferent neurones have their cell bodies in the
anosensation (p. 1135) (Sanders et al 2014). Defective ICC function has
intermediolateral grey matter (lamina VII) of the thoracolumbar seg-
been implicated in a wide range of gastrointestinal motility disorders


ments of the spinal cord; those destined for the smooth muscle of the
(Al-Shboul 2013), and in the development of gastrointestinal stromal
gut mostly pass through the sympathetic chain without synapsing and
tumours (Roggin and Posner 2012).
relay in prevertebral ganglia (coeliac, mesenteric and pelvic), whereas
Cells with a similar morphology have been found in association
those mediating vasoconstriction synapse in the sympathetic chain or
with smooth muscle at many other sites, such as the urethra, ductus
prevertebral ganglia. Postganglionic sympathetic fibres are distributed
deferens, prostate, bladder, corpus cavernosum, ureter, uterine tube, and
with the branches of the coeliac trunk and mesenteric arteries to three
uterus. They may act as electrical pacemakers in the urethra and ureter
principal targets: the myenteric and submucosal ganglia (causing inhi-
but their role at other sites is less certain (Drumm et al 2014).
bition), blood vessels (inducing vasoconstriction) and sphincter muscle
(inducing contraction).
Serosa and adventitia
Visceral sensory endings are distributed throughout the layers of the
gut wall. They respond to various stimuli, including excessive muscular
A layer of connective tissue, of variable thickness, lies external to the contraction or distension, ischaemia and inflammation; their cell
muscularis externa. In many places, it contains adipose tissue. Where bodies are located in the nodose ganglion of the vagus nerve (vagal
the gut is covered by visceral peritoneum, the external layer is a serosa, afferents) and in thoracic and lumbosacral dorsal root ganglia (visceral
consisting of mesothelium overlying a thin layer of connective tissue. afferents, which run with sympathetic efferents). Their central projec-
In extraperitoneal regions, the surfaces of the gut in contact with the tions reach the brainstem and spinal cord, respectively. Vagal afferents
peritoneum are covered by serosa, while other parts are covered by con- are more numerous in the foregut than the midgut and are concerned
nective tissue that blends with the surrounding fasciae and is referred with physiological responses such as satiety, whereas pain and discom-


to as an adventitia. fort are mediated by spinal pathways.
Vascular plexuses Intrinsic innervation
The intrinsic innervation of the gut is derived from enteric neurones
Vascular plexuses are present at various levels of the wall, especially in distributed throughout its wall in thousands of small ganglia, each
the submucosa and mucosa; they connect with vessels that supply the consisting of neuronal cell bodies supported by enteric glial cells; it is
surrounding tissues or those entering through the mesentery, and estimated that there are between 200 and 600 million neurones in the
accompany the ducts of outlying glands. human enteric nervous system. Enteric neurones are derived from
neural crest cells. The enteric nervous system innervates the gut from
Innervation
oesophagus to anus, together with the pancreas and biliary tree.
The majority of enteric neurones in the wall of the gut are found in
The gut wall is densely innervated by both the enteric nervous system two ganglionated plexuses (Fig. 59.10). The most extensive of these is
(intrinsic control) and the autonomic nervous system (extrinsic control). the myenteric (Auerbach’s) plexus, which consists of a network of nerve
Myenteric plexus
Circular muscle
Longitudinal muscle Deep muscular plexus
Inner SMP
Outer SMP
Submucosal artery
Mucosa
Muscularis mucosae
Fig . 59 .10 The organization of the enteric nervous system in the human small intestine . There are two ganglionated plexuses: the myenteric plexus
between the longitudinal and circular layers of the external musculature, and the submucosal plexus (SMP), which has outer and inner components .
Nerve fibre bundles connect the ganglia and form plexuses innervating the longitudinal muscle, circular muscle, muscularis mucosae, intrinsic arteries
and the mucosa . Axons of extrinsic origin also run in these nerve fibre bundles . There are also innervations of gastroenteropancreatic (GEP) endocrine
cells and gut-associated lymphoid tissue (GALT), which are not shown here . (Redrawn with permission from Furness JB . The enteric nervous system and


neurogastroenterology . Nat Rev Gastroenterol Hepatol 2012;9:286–294 . Reprinted with permission from Nature Publishing Group .)


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NOITCES
fibres and small ganglia lying between the circular and longitudinal mesenteric and splenic veins behind the neck of the pancreas); the
layers of the muscularis externa. It runs in continuity from the oesopha- hilum of the left kidney (the hilum of the right kidney is slightly lower);
gus to the anus. The submucosal (Meissner’s) plexus has outer and the origin of the renal arteries; the level of the duodenojejunal flexure
inner components, and is present throughout the intestine but absent (Mirjalili 2012b); and the termination of the spinal cord. The pylorus
or minimal in the oesophagus and stomach. may be found in the transpyloric plane but is not a constant feature.
Interconnecting, non-ganglionated nerve plexuses lie at various The subcostal plane is defined by a line that joins the lowest point
levels in the wall of the gut, including the lamina propria (mucosal of the costal margin on each side (usually, the tenth costal cartilage); it
plexus), at the interface between the submucosa and muscularis externa, is most commonly at the level of the second lumbar vertebra (range
between the circular and longitudinal muscles (the non-ganglionated T12/L1 disc to upper L3) (Mirjalili et al 2012a).
part of the myenteric plexus), and within the serosa. The supracristal plane joins the highest point of the iliac crest on
Individual enteric neurones function in one of several ways: as affer- each side. It serves as a useful landmark when performing a lumbar
ent (sensory) nerves responding to mechanical and chemical stimuli; puncture or spinal injection, and usually lies at the level of the L4 body
as efferent (motor) nerves innervating epithelial cells (influencing or L4/5 disc and its spinous process (see Fig. 78.16). The bifurcation of
absorption, secretion and/or the release of hormones), smooth muscle the abdominal aorta lies approximately in this plane (Mirjalili et al


(excitatory or inhibitory), arterioles (vasoconstriction or vasodilation) 2012a).
and lymphoid tissue; or as interneurones that relay and integrate The transtubercular plane joins the tubercles of the iliac crests and
signals. Collectively, they are involved in a hierarchy of enteric reflexes is traditionally reported to lie at the level of the body of L5, near its
that include local reflexes within the gut wall; reflexes mediated through upper border. It is an approximate landmark for the origin of the infe-
prevertebral sympathetic ganglia; and reflexes mediated through the rior vena cava from the confluence of the common iliac veins.
central nervous system (the gut–brain axis). The functions of enteric The plane of the pubic crest is in line with the upper border of the
neurones may be further modulated by local environmental factors, e.g. pubic symphysis. In supine individuals, this plane frequently intersects
enteric glia, gut microbiota and feeding state, and by general factors in the tip of the coccyx and the femoral head (Mirjalili et al 2012a), but
the host, e.g. the immune system, stress and disease (Brierley and there are variations relating to the degree of lumbar lordosis, sacral
Linden 2014). Pathological states become manifest by abnormal secre- inclination and pelvic tilt.
tion, impaired absorption, disordered gastrointestinal motility and
Abdominal regions
pain.
The abdomen can be divided into nine regions using the subcostal,
transtubercular and two paramedian planes (Fig. 59.11A). These regions
SURFACE ANATOMY OF THE ABDOMEN are used in clinical practice for descriptive localization of a patient’s
AND PELVIS pain or tenderness, or the position of a mass, and can be used to refer-
ence the position of abdominal viscera. From superior to inferior, the
ABDOMINAL PLANES AND REGIONS nine regions are: the epigastrium, flanked by the right and left hypo-
chondrium; the umbilical, or central, flanked by the right and left
lumbar; and the suprapubic or hypogastrium, flanked by the right and
For descriptive purposes, the abdomen can be divided into regions


left iliac fossae. In practice, these regions are often loosely defined
using a combination of horizontal and vertical planes that are based
without strict reference to their boundaries. An alternative system of
on skeletal landmarks. Published descriptions of surface anatomy
description involves dividing the abdomen into quadrants using the
largely apply to adults, in whom attempts have been made to validate
median plane and a horizontal line passing through the umbilicus.
or update standard descriptions using cross-sectional imaging. The
extent to which many of these surface projections can be extrapolated
to children is uncertain; some differences are inevitable, particularly in ANTERIOR ABDOMINAL WALL
infants, given their different visceral and body proportions (Stringer
2011). In this chapter, descriptions of the surface projections of abdomi-
Skeletal landmarks
nal structures refer to the most commonly encountered arrangement
The superior boundary of the anterior abdominal wall is formed by
seen in adults. However, it is important to note that there is consider-
several clear landmarks (Fig. 59.11B). The xiphoid process is palpable
able individual variation in surface anatomy, compounded further by
at the inferior sternum, in the midline. From here, the costal margins
potential variations related to age, sex, posture, respiration, body mass
can be felt passing inferolaterally from the seventh costal cartilage at the
and ethnicity (Mirjalili and Stringer 2012).
xiphisternal joint to the tip of the twelfth rib (the latter is often difficult
Vertical lines and planes to feel in the obese or if it is short). The lower border of the ninth costal
The midline (or median plane) passes through the xiphoid process and cartilage can usually be defined as a distinct ‘step’ along the costal
the pubic symphysis. There are two paramedian lines, left and right, margin. The lowest part of the costal margin lies in the mid-axillary line
that extend from the mid-clavicular point to the mid-inguinal point, a and is formed by the inferior margin of the tenth costal cartilage.
point midway between the anterior superior iliac spine and the pubic The inferior boundary of the anterior abdominal wall is formed,
symphysis (Fig. 59.11A); this line crosses the costal margin just lateral from lateral to medial, by the iliac crest, which descends to the anterior


to the tip of the ninth costal cartilage. In the upper abdomen, it approxi- superior iliac spine; the inguinal ligament, which runs obliquely down-
mates to the lateral border of rectus abdominis. wards to the pubic tubercle; and the pubic crest, which extends from
the pubic tubercle laterally to the pubic symphysis in the midline. The
Horizontal lines and planes
pubic tubercle is palpable on the anterosuperior surface of the pubic
Several horizontal reference planes have been defined but, with modern bone approximately 2 cm lateral to the midline. The prominent tendon
cross-sectional imaging, their clinical utility for positioning abdominal of adductor longus (best felt with the hip flexed, abducted and exter-
viscera has become limited. Nevertheless, they help to conceptualize nally rotated) attaches to the pubis directly below the pubic tubercle,
the relative positions of abdominal viscera with respect to vertebral and can therefore be used to verify its position.
levels and bony surface landmarks. The posterolateral boundary of the anterior abdominal wall is the
The xiphisternal joint most often lies in the same horizontal (axial) mid-axillary line.
plane as the T9 vertebra (Mirjalili et al 2012b).
Soft tissue landmarks
The transpyloric plane lies midway between the suprasternal notch
of the manubrium and the upper border of the pubic symphysis. This umbilicus
corresponds to a plane that is approximately midway between the The umbilicus is an obvious but inconstant landmark. In the supine
xiphisternal joint and the umbilicus, or slightly below (Mirjalili et al adult, it usually lies around the L4 level (range L2/3 disc to upper S1)
2012a). Posteriorly, the plane intersects the lower half of the body of (Mirjalili et al 2012b). The umbilicus may lie at a lower level in the
the first lumbar vertebra, the L1/2 intervertebral disc, or the upper half erect position, and in children, the obese and in individuals with a
of the body of the second lumbar vertebra in most individuals (range pendulous abdomen.


lower T12 to lower L2); it sits higher in males (lower L1–L1/2) than
females (lower L2) (Mirjalili et al 2012a). Anteriorly, it intersects the rectus abdominis
costal margin at the ninth costal cartilage, where the linea semilunaris In a thin, muscular individual, the tendinous intersections of rectus
crosses, and where a distinct ‘step’ may be palpable in the rib margin. abdominis may be visible, especially when the muscle is tensed by
The following structures lie approximately within the transpyloric plane lifting the head against resistance or by sitting up; the intersections are
(Mirjalili et al 2012a, 2012b): the origin of the superior mesenteric usually situated at the level of the umbilicus, the level of the xiphoid
artery; the origin of the portal vein (from the confluence of the superior process and midway between these two points (Fig. 59.11B).


Surface anatomy of the abdomen and pelvis
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A B
10 10
1 2 3
1 2 3 4 D1
5
D2 D4
6
11
D3
7
4 5 6
8
9
10
12
7 8 9
C
T11
T12
1
L1
L2
L3
2 L4
L5
Fig . 59 .11 A, Nine regions of the anterior abdominal wall . Key: 1, right hypochondrium; 2, epigastrium; 3, left hypochondrium; 4, right lumbar; 5,
umbilical/central; 6, left lumbar; 7, right iliac fossa; 8, suprapubic/hypogastrium; 9, left iliac fossa; 10, paramedian line; 11, subcostal plane; 12,
transtubercular plane . B, The surface projection of the abdominal viscera . Key: 1, diaphragm position: right dome level with fifth intercostal space and
left dome with sixth rib; 2, liver: mapped between three points: right fifth rib/intercostal space mid-clavicular line, left fifth intercostal space/sixth rib
mid-clavicular line and right tenth costal cartilage mid-axillary line; 3, zone of gastro-oesophageal junction position (white): mainly located posterior to left
seventh costal cartilage, at approximately T11; 4, transpyloric plane; 5, zone of gallbladder fundus position (white); 6, duodenum: four parts marked
D1–D4; 7, linea semilunaris; 8, position of small intestine mesentery; 9, linea alba; 10, tendinous intersection of rectus abdominis . C, The surface position
of the spleen and kidneys . Key: 1, spleen; sits deep to ribs 10–12 with long axis aligned with rib 11; 2, supracristal plane . (C, Derived with permission


from Mirjalili SA, McFadden SL, Buckenham T, Stringer MD . 2012b A reappraisal of adult abdominal surface anatomy . Clin Anat 25:844–50 .)
linea alba Inferior epigastric artery
The linea alba is usually only visible in thin, muscular individuals. It is The inferior epigastric artery lies along the medial border of the deep
wider and more obvious above the umbilicus, and is almost linear and inguinal ring immediately above the inguinal ligament. Up to the level
less visible below this level (Ch. 61) (Fig. 59.11B; see Fig. 61.2). of the umbilicus, it follows a course that lies approximately 40% of the
distance between the midline and a sagittal plane running through the
linea semilunaris anterior superior iliac spine (Epstein et al 2004). The surface anatomy
The linea semilunaris lies along the lateral margin of the rectus sheath of the artery is particularly important in laparoscopic surgery because
and is visible as a shallow, curved groove in muscular individuals, par- trocar insertion may injure the vessel, causing a rectus sheath hae-
ticularly when the abdominal muscles are tensed, e.g. by sitting up from matoma or intra-abdominal bleeding. The artery can be avoided if a
the lying position (Fig. 59.11B). It passes from the ninth costal cartilage trocar is inserted at least two-thirds of the distance along a horizontal
to the pubic tubercle. line between the midline and a sagittal plane passing through the ante-
rior superior iliac spine.
mid-inguinal point
Superficial reflexes
The mid-inguinal point lies at the midpoint of a line between the pubic
symphysis and the anterior superior iliac spine. In adults, it is the Cremasteric reflex
approximate surface marking of the femoral artery (just below the liga- Stroking the skin of the medial side of the thigh evokes a reflex con-
ment) and the deep inguinal ring (just above the ligament) (Hale et al traction of cremaster, which elevates the ipsilateral testis. The reflex is
2010). mediated by the genitofemoral nerve (L1 and L2 nerve roots), although


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NOITCES
the afferent arc of the reflex may be via sensory fibres in the ilioinguinal line to the left fifth intercostal space/sixth rib in the mid-clavicular line,
nerve. The reflex is usually absent if there is torsion of the testicle. and can be mapped with the contour of the diaphragm (Mirjalili et al
2012c). This border curves slightly downwards at its centre and crosses
Superficial abdominal reflex the midline behind the xiphisternal joint. The right border of the liver
Gently stroking each of the four quadrants of the anterior abdominal is curved to the right and joins the upper and lower right limits. The
wall normally elicits a visible contraction of ipsilateral abdominal upper border of the liver may be defined by dullness to percussion when
muscles. The reflex can be used to help localize lesions in the spinal compared with the resonance of the lungs above.
cord but is now of minor clinical significance because of the availability
of neuroimaging and the difficulties of eliciting the reflex in multipa- Gallbladder
rous women, the elderly and the obese (Gosavi and Lo 2014). The fundus of the gallbladder is commonly identified with the tip of
the ninth costal cartilage (in the transpyloric plane), near the junction
of the linea semilunaris with the costal margin (see Fig. 59.11B). Recent
INTRA-ABDOMINAL VISCERA
data have shown that the fundus lies in the transpyloric plane in
approximately one-third of supine individuals and below the plane in
The surface markings of the intra-abdominal viscera are variable and most others (Mirjalili et al 2012b).
depend on age, sex, body habitus, nutritional state, phase of ventilation
and body position. The availability of cross-sectional and ultrasound Spleen
medical imaging of the abdominal viscera has led to a decline in the use The spleen is traditionally described as sitting on the left posterolateral
of surface anatomy, except for descriptive purposes. The following abdominal wall deep to ribs 9–11. Recent data show that the spleen sits


descriptions are, at best, regarded as the most common or approximate deep to ribs 10–12 in 50% of subjects and deep to ribs 9–11 in 25% of
markings in a healthy supine adult (Fig. 59.11B,C). The spinous proc- supine individuals; its long axis corresponds most closely to the elev-
esses of the lumbar vertebrae can be used to locate vertebral levels, with enth rib or tenth rib, respectively, and passes anterior to the mid-axillary
the lower part of the spinous process marking the level of the interverte- line in most subjects (Mirjalili et al 2012b) (see Fig. 59.11C). The spleen
bral disc below the correspondingly numbered vertebra. extends from a point about 5 cm to the left of the posterior midline at
the level of the eleventh thoracic spine and extends about 3 cm anterior
Diaphragm
to the mid-axillary line. Its normal size approximates roughly to that
In the supine position at end-tidal inspiration, the dome of the dia-
of the individual’s clenched fist.
phragm is most frequently located level with the fifth intercostal space
in the mid-clavicular line on the right and the sixth rib in the mid-
clavicular line on the left, and ranges from the fourth intercostal space RETROPERITONEAL VISCERA
to below the costal margin (Mirjalili et al 2012c) (see Fig. 59.11B) (see
Ch. 55 for further discussion of the diaphragm). These levels are
The surface projections of the retroperitoneal viscera are reasonably
approximate, not only because of individual variation but also because
reliable but have limited clinical utility since most interventions and
diaphragmatic excursion in the erect position during quiet breathing is
procedures are guided by medical imaging.
about 2 cm and increases to about 7 cm during deep breathing (Bous-
suges et al 2009). The dome of the diaphragm can reach as high as the Pancreas
fourth rib on maximal expiration.
The surface projection of the head of the pancreas lies within the duo-
Stomach denal curve on the right side of the second lumbar vertebra; the neck


lies in the transpyloric plane, level with the L1/2 intervertebral disc; and
The gastro-oesophageal junction lies to the left of the midline, posterior
the body passes obliquely up and to the left towards the spleen, lying
to the left seventh costal cartilage, at the level of the eleventh thoracic
slightly above the transpyloric plane, near the tail.
vertebra (range upper T10 to L1/2), with the level being lower in females
and higher in the obese (Mirjalili et al 2012b) (see Fig. 59.11B). The
Kidney
stomach lies in a curve within the left hypochondrium and epigastrium,
The right kidney usually lies, on average, 2 cm lower than the left,
although, when distended, it may lie as far down as the umbilical or
although, in 10% of cases, the left kidney sits lower than the right
suprapubic regions. The epigastrium is the usual place to auscultate for
(Mirjalili et al 2012b). The vertebral limits of the left kidney are T12–
a ‘succussion splash’ caused by gastric outlet obstruction or stasis, and
L3 or L4, while those for the right kidney are L1–L4 (overall range
is also the region where a thickened pylorus is palpable in infantile
upper T11 to lower L5) (see Fig. 59.11C). The upper poles of both
hypertrophic pyloric stenosis.
kidneys lie anterior to rib 12, and they lie anterior to the rib 11 in 30%
Duodenum (left) and 10% (right) of subjects. In supine adults at end-tidal inspira-
The first part of the duodenum sometimes ascends above the transpy- tion, the centre of the renal hilum usually lies at L1/2 or L2 on the left
loric plane; the second part usually lies just to the right of the midline, and at a slightly lower vertebral level on the right. It is important to
alongside the second and third lumbar vertebrae; the third part usually note that both kidneys move vertically by a mean of about 2 cm during