layered, functional groups (Table 48.1). The muscles of the shoulder a broad triangular aponeurosis from the sixth cervical to the third tho
girdle may suspend or move the scapula; these functions are inter racic vertebrae, and by short tendinous fibres below this.
dependent. The muscles of the shoulder joint may stabilize the joint, Superior fibres descend, inferior fibres ascend, and the fibres between
move the arm on the stable shoulder joint, or coordinate shoulder and them are directed horizontally; all converge laterally on the scapula.
elbow movement; these functions are also interdependent. The closer The superior fibres are attached to the posterior border of the lateral
a muscle is to the centre of motion of the joint on which it acts, the third of the clavicle; the middle fibres to the medial acromial margin
greater its effect on the stability of that joint at rest and during motion. and superior lip of the crest of the scapular spine; and the inferior fibres
The farther away from the centre of motion, the greater the effect of the pass into an aponeurosis that glides over a smooth triangular surface at
resultant muscular vector on translation of the joint surfaces. As an the medial end of the scapular spine and is attached to a tubercle at its
lateral apex.
Variants The clavicular attachment of trapezius varies in extent, some
Table 48.1 The relationship between functional muscle grouping and actions of the
pectoral girdle* times reaching midclavicle, and occasionally blending with sternoclei
domastoid. The vertebral attachment sometimes stops at the eighth
Functional group Specific muscles Action thoracic spine. The occipital attachment may be absent. Cervical and
Occipitospinoscapular Trapezius Scapular suspension dorsal parts are occasionally separate. The inferior part may be hypo
Thoracoscapular Pectoralis minor Position and motion of the plastic or absent.
acromioclavicular joint in relation
Spinoclavicular Trapezius
Thoracoclavicular Subclavius Det co e lt eh re a tt ih onor a ox f ta hn ed l a(n tee ru ar l) a cx lais vicle Vascular supply The upper third of trapezius is supplied by a trans
verse muscular branch that arises from the occipital artery at the level
during motion


of the mastoid process. It enters the muscle on its deep surface and gives
Thoracoscapular Levator scapulae Scapular motion
(medial border) Rhomboid minor Position and motion of the off several musculocutaneous perforators to the overlying skin. The
Rhomboid major glenohumeral joint in relation to middle portion of trapezius, together with an area of overlying skin, is
Serratus anterior the thorax and (neur)axis supplied by the superficial cervical artery or by a superficial branch of
Serratus posterior superior
the transverse cervical artery, via musculocutaneous perforators. The
Serratus posterior inferior
lower third of trapezius is supplied by a muscular branch from the
Thoracohumeral Pectoralis major Thoracobrachial motion
dorsal scapular artery, passing medial to the medial border of
Latissimus dorsi Position of the arm
the scapula. It reaches the deep surface of the muscle either by piercing
Scapulohumeral Deltoid
the rhomboids or by passing between rhomboids major and minor
Coracobrachialis
Biceps brachii (short head) at the level of the base of the spine of the scapula. It anastomoses with
Teres minor Concavity compression of the the medial and lateral perforating branches of the posterior intercostal
Infraspinatus glenohumeral joint arteries.
Supraspinatus
Subscapularis
Teres major Innervation Trapezius is innervated by the accessory nerve (see Chs
Triceps brachii (long head) Coordination of shoulder and elbow 29 and 46 for more details). Sensory (proprioceptive) branches are
Biceps brachii (long head) motion derived from the ventral rami of C3 and C4.
*As a principle, a muscle will act on a motion segment to alter the position of the distal extent of that Actions Trapezius cooperates with other muscles in steadying
segment in space. As an example, deltoid acts on the shoulder joint but its effect is to move the distal the scapula, controlling it during movements of the arm and maintain
extent of the humerus, i.e. the elbow. ing the level and poise of the shoulder. Electromyographic activity is


Shoulder girdle and arm
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The axillary nerve and vessels may be injured during dislocation or,
more commonly, during inexpert attempts at relocation, particularly in
older patients. This can lead to an inability to maintain abduction of
the shoulder as a result of paralysis of deltoid. If, after relocation of the
joint, the patient cannot initiate elevation (abduction) from the pendant
position, then there may be an associated rotator cuff rupture and/or
suprascapular nerve lesion. If the patient can initiate, but cannot main
tain, abduction beyond 15°, then deltoid palsy should be suspected.
Patients, particularly the elderly, can have a rotator cuff rupture and an
axillary nerve palsy causing deltoid paralysis; it can be difficult to dis
tinguish between the two. There may also be an area of hypoaesthesia
or anaesthesia over the distal part of the muscle (sometimes referred to
as the ‘regimental badge patch’ of skin; see Fig. 48.2), reflecting loss of
function in the upper lateral cutaneous nerve of the arm (a branch of
the axillary nerve), as well as venous occlusive changes (swelling) in the
limb. After more violent dislocation, younger patients may have deltoid
paralysis and an intact, but stretched, rotator cuff or partial tearing of
the tendons, with a suprascapular nerve injury; these patients may have
unexpected pain in the supraspinous fossa with weakness of infraspina
tus (lateral rotation), as well as the anticipated anterior shoulder pain.
Posterior dislocation is rare and typically occurs when violent move
ments produce marked medial rotation and adduction, e.g. in epileptic
seizures or electric shock. The upper limb is held in fixed medial rota
tion, and external rotation is impossible to perform.


muscles
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minimal in the unloaded arm, and heavy loads can be suspended with margins and outer surfaces of the third to fifth ribs (frequently, second
only a small contribution from the upper part; it is the lower part of to fourth), near their cartilages, and from the fascia over the adjoining
the muscle that resists lateral rotation of the scapula under load. Acting external intercostal muscles. Its fibres ascend laterally under cover of
with levator scapulae, the upper fibres elevate the scapula and, with it, pectoralis major, converging in a flat tendon that is attached to the
the point of the shoulder; acting with serratus anterior, the lower fibres medial border and upper surface of the coracoid process of the scapula.
of trapezius protract and rotate the scapula medially (upwards) so that Part or all of the tendon may appear to cross the coracoid process into
the arm can be raised above the head; acting with the rhomboids, it the coracoacromial ligament.
retracts the scapula, bracing the shoulder. With the shoulder fixed,
trapezius may bend the head and neck backwards and laterally. Tra Variants Slips of the muscle are sometimes separated and vary in
pezius, pectoralis minor, levator scapulae, rhomboids and serratus an number and level. In rare cases, one passes from the first rib to the
terior combine to produce a variety of scapular rotations see below. coracoid (pectoralis minimus). The costal attachments can be second
If the muscle is denervated, the functions of trapezius cannot be to fifth ribs; third to fifth; second to fourth; or third to fourth. The
substituted readily by muscle transfer; its unique suite of complex muscle may be present or absent when pectoralis major is absent (in
actions suggest that it should rarely, if ever, be used as a muscle for Poland’s syndrome).
transfer elsewhere.
Relations Pectoralis major, the lateral pectoral nerve and pectoral
Testing The upper fibres of trapezius are palpated while the shoulder branches of the thoracoacromial artery are anterior. The ribs, external


is shrugged against resistance (see Video 46.1). The lower fibres are intercostals, serratus anterior, the axilla, axillary vessels, lymphatics and
palpated during scapular retraction. A better discriminative test is as brachial plexus are all posterior. The upper border of pectoralis minor
follows: the hand is brought by medial rotation to the small of the back is separated from the clavicle by a triangular gap filled by the clavipec
and the patient is asked to maintain it firmly in this position while the toral fascia, behind which are the axillary vessels, lymphatics and
examiner tries to pull the hand off the back. The lower fibres of the nerves. The lateral thoracic artery follows the lower border of the muscle.
trapezius are activated to hold the scapular spine horizontal. Failure to The medial pectoral nerves pierce and partly supply the muscle.
do so implies paresis or paralysis of trapezius, but this must be distin
guished from congenital hypoplasia of the lower fibres of the muscle. Vascular supply Pectoralis minor is supplied by pectoral and deltoid
Trapezius palsy results in a characteristic posture: the shoulder is branches of the thoracoacromial and superior and lateral thoracic
tilted laterally and forwards, the acromioclavicular joint is lowered, the arteries.
superior pole of the scapula is rotated upwards and the inferior pole is
displaced medially and, usually, away from the chest wall. This distin Innervation Pectoralis minor is innervated by branches of the medial
guishes trapezius palsy from that of serratus anterior, in which the entire and lateral pectoral nerves: C5, 6, 7, 8 and T1.
medial border of the scapula tends to elevate away from the chest wall
(socalled ‘winging’). The scapula is displaced upwards and towards the Actions Pectoralis minor assists serratus anterior in drawing the
spine (see p. 838). The altered posture and disordered motion of the scapula forwards around the chest wall. With levator scapulae and the
scapula create distortion (narrowing and elongation) of the cervico rhomboids, it rotates the scapula, depressing the point of the shoulder.


axillary sheath and its contents; symptoms of reduced venous return, It resists scapular rotation caused by trapezius. Both pectoral muscles
lymphatic obstruction and disturbed neural perfusion (pain, paraesthe are electromyographically quiescent in normal inspiration, but are
siae, dysaesthesiae) are almost universal. active in forced inspiration.
Pectoralis minor Subclavius
Attachments Pectoralis minor is a thin, triangular muscle lying pos Attachments Subclavius is a long, asymmetric triangular muscle
terior (deep) to pectoralis major (Fig. 48.25). It arises from the upper between the clavicle and the first rib (see Fig. 48.25). It arises from
Levator scapulae Scalenus posterior
Longus capitis Acromion
Pectoralis minor (cut)
Scalenus medius
Scalenus anterior
Omohyoid, superior belly
Sternothyroid
Pectoralis major (cut)
Omohyoid, inferior belly
Clavicle Deltoid
Sternocleidomastoid Biceps brachii, long head
I
Subclavius Biceps brachii, short head
Internal intercostal
Coracobrachialis
II
External intercostal
Teres major
Pectoralis minor
Subscapularis
Serratus anterior
IV
Pectoralis major Serratus anterior
V
Latissimus dorsi
Costal margin
VI Rectus abdominis
Linea alba External oblique
VII (cut and reflected)
Fig. 48.25 Deep muscles of the chest and left shoulder girdle, anterior aspect. Roman numerals refer to costal cartilages. (With permission from
Waschke J, Paulsen F (eds), Sobotta Atlas of Human Anatomy, 15th ed, Elsevier, Urban & Fischer. Copyright 2013.)


Shoulder girdle and arm
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the junction of the first rib and its costal cartilage by a thick tendon,
prolonged at its inferior margin and anterior to the costoclavicular liga
ment. It passes upwards and laterally to attach by direct muscular fibres
into a groove on the undersurface of the middle third of the clavicle; Semispinalis capitis
the lower and most lateral fibres are the longest. Subclavius may be Splenius capitis
attached to the coracoid process or the upper border of the scapula as Sternocleidomastoid Rhomboid minor
well as, or instead of, the clavicle.
Rhomboid major
Relations Posteriorly, subclavius is separated from the first rib by the
Trapezius Levator scapulae
subclavian vessels and brachial plexus; anteriorly, it is separated from
Supraspinatus
pectoralis major by the anterior lamina of the clavipectoral fascia. The
Deltoid
suprascapular artery, which has a variable pattern, descends behind the Infraspinatus
muscle, passing between it and omohyoid anteriorly and the subclavian
vessels posteriorly; the artery, therefore, has a close relationship to the
posterior surface of the clavicle, a feature that makes it susceptible to
injury during clavicular fracture and surgical fixation.
Vascular supply Subclavius is supplied by the clavicular branch of
the thoracoacromial artery and the suprascapular artery.
Innervation Subclavius is supplied by the subclavian branch of the
brachial plexus (the nerve to subclavius), C5 and 6. A muscle, however
apparently insubstantial, that has a unique, solitary nerve supply must
have an important function; subclavius is no exception (see above and
below). Triangle of Teres minor
auscultation Teres major
Actions Subclavius resists accelerated elevation and rotation of the
Latissimus dorsi Serratus
clavicle during elevation of the shoulder girdle, and may help to close
anterior
pack the medial end of the clavicle against the articular disc of the Thoracolumbar


sternoclavicular joint for greater stability under load. It is inaccessible fascia Serratus posterior
inferior
to palpation and difficult to investigate by electromyography. Inciden
External oblique
tally, it ‘protects’ the subclavian vessels and brachial plexus that lie Erector spinae
Internal oblique
behind it. Internal oblique
forming floor of
lumbar triangle
MUSCLES OF SCAPULAR MOTION Fig. 48.26 Muscles of the back and shoulder girdles. Superficial muscles
are shown on the left. Deeper muscles, revealed after excision of deltoid,
Levator scapulae latissimus dorsi and trapezius, are shown on the right.
Attachments Levator scapulae is a slender muscle attached by
tendinous slips to the transverse processes of the atlas and axis, and
to the posterior tubercles of the transverse processes of the third and Variants There is some variability in the vertebral and scapular attach
fourth cervical vertebrae (see Fig. 29.6; Fig. 48.26). It descends diago ments of rhomboids major and minor. A slip of muscle may extend
nally to attach to the medial scapular border between its superior from the upper border of rhomboid minor to reach the occipital bone
angle and the triangular smooth surface at the medial end of the (rhomboid occipitalis).
scapular spine.
Rhomboid major
Variants Levator scapulae varies considerably in its vertebral attach Attachments Rhomboid major is a quadrilateral sheet of muscle that
ments and the extent to which it separates into slips. There may be arises by tendinous fibres from the spines and supraspinous ligaments
accessory attachments to the mastoid process, occipital bone, first or of the second to fifth thoracic vertebrae, and descends laterally to the
second rib, the scaleni, trapezius and the serratus muscles. medial border of the scapula between the root of the spine and the
inferior angle (see Fig. 48.26). Most of its fibres usually end in a tendi
Vascular supply Levator scapulae receives its arterial supply mainly nous band between these two points, joined to the medial border by a


from the transverse cervical and ascending cervical arteries. The verte thin membrane. Occasionally, this is incomplete, in which case some
bral extremity of the muscle is supplied by branches from the vertebral muscular fibres are attached directly into the scapula. The attachments
artery. of rhomboid major (and also those of rhomboid minor, levator scapu
lae and serratus anterior) may be more extensive, with ‘folds’ or exten
Innervation Levator scapulae is innervated directly by branches of the sions passing to both dorsal and costal aspects of the scapula adjacent
third and fourth cervical spinal nerves, and from the fifth cervical nerve to its medial margin.
via the dorsal scapular nerve.
Vascular supply of the rhomboids Rhomboids major and minor
Actions Levator scapulae elevates the superior angle of the scapula. are supplied by the dorsal scapular artery or the deep branch of the
If unopposed, this causes a lateral rotation of the scapula. With the transverse cervical artery and by dorsal perforating branches from the
cervical vertebral column fixed, levator scapulae acts with trapezius to upper five or six posterior intercostal arteries.
elevate the scapula or to sustain a weight carried on the shoulder;
with the shoulder fixed, the muscle inclines the neck to the same Innervation of the rhomboids Rhomboids major and minor are
side. innervated by a branch of the dorsal scapular nerve, C4, 5.
Rhomboid minor
Actions of the rhomboids Both rhomboid major and rhomboid
Attachments Rhomboid minor is a small, cylindrical muscle. It runs minor retract the medial border of the scapula superiorly and medially,
from the lower ligamentum nuchae and the spines of the seventh cervi and are used in retraction of the shoulders.
cal and first thoracic vertebrae to the base of a smooth triangular surface
at the medial end of the spine of the scapula, where dorsal and ventral Testing of the rhomboids Rhomboids major and minor can be
layers enclose the inferior border of levator scapulae (see Fig. 48.26). palpated deep to trapezius on bracing the shoulder back against resist


The dorsal layer of rhomboid minor is attached to the rim of the trian ance with the arm in elevation at shoulder level.
gular surface, dorsolateral to and below levator scapulae. The ventral
layer is strong and wide, extending 2–3 cm medial to and below levator Serratus anterior
scapulae; here, the fasciae of rhomboid minor and serratus anterior are Attachments Serratus anterior is a large muscular sheet that curves
fused. Rhomboid minor is usually separate from rhomboid major, but around the thorax. It arises from an extensive costal attachment and
the muscles overlap and are occasionally united. inserts on the scapula (see Fig. 48.25). Fleshy digitations arise anteriorly


muscles
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from the outer surfaces and superior borders of the upper eight to ten when asthmatics and athletes may be observed to fix the scapula by
ribs, and from fasciae that cover the intervening intercostal muscles. The grasping a rail or other support.
line of origin of the muscle is long and slightly curved, and passes
inferolaterally around the thorax. There are three parts: the upper fibres Testing The muscular digitations of serratus anterior can be seen and
arise from the first and second ribs and intercostal fascia, the middle felt when the outstretched hand pushes against resistance.
fibres arise from the third to sixth ribs, and the lower fibres interdigitate When serratus anterior is paralysed, the medial border of the scapula,
with the upper five slips of external oblique. The muscle follows and especially its lower angle, stand out prominently. The arm cannot
the contour of the chest wall closely, reaching the medial border of be raised fully. Pushing is ineffective; indeed, attempts to do so produce
the scapula anterior to subscapularis. The first (uppermost) digitation further projection, known as ‘winging’ of the scapula (Streit et al 2012;
encloses, and is attached to, a triangular area of both the costal and the see p. 831).
dorsal surfaces of the superior scapular angle. The next two or three
Serratus posterior inferior
digitations form a triangular sheet that is attached to the costal surface
along almost its entire medial border. The lower four or five digitations Serratus posterior inferior is described on page 942 (see Fig. 48.26).
converge to be attached by musculotendinous fibres to a triangular
Serratus posterior superior
impression on the costal surface of the inferior angle; they enclose the
Serratus posterior superior is described on page 941.
inferior angle and are also attached to a smaller triangular part of its
dorsal surface near its tip.
MUSCLES OF THORACOBRACHIAL MOTION
Variants Digitations may be absent, particularly the first and eighth,
and sometimes also the intermediate part. Serratus anterior may be
The large muscles from the trunk to the arm, and from the scapula to


partly fused with levator scapulae, adjacent external intercostals or
the arm, act on the shoulder joint. Pectoralis major and latissimus dorsi
external oblique.
are attached to the metaphysis of the humerus below the centre of rota
tion of the joint, while deltoid and coracobrachialis are attached to the
Vascular supply Serratus anterior is supplied by superior and lateral
midpoint of the diaphysis or shaft, some way from the centre of rotation
thoracic arteries, and by branches from the thoracodorsal artery before
of the shoulder joint. These four muscles move the arm in relation to
(occasionally, after) it divides in latissimus dorsi.
the shoulder joint, so that, although they act through the shoulder joint,
their role is to position the elbow joint (and, thus, the hand) in space.
Innervation Serratus anterior is innervated by the long thoracic nerve, The continuous sheet of muscle that is pectoralis major and deltoid
C5, 6 and 7, which descends on the external surface of the muscle. positions the elbow through a wide, asymmetrical, conical range of
motion from adduction across the trunk with medial rotation, through
Actions With pectoralis minor, serratus anterior protracts (draws for flexion, abduction and external rotation, into extension at the shoulder.
wards) the scapula, as a prime mover in all reaching and pushing move The cervical spinal segmental levels at which this range of movement
ments. The upper part, with levator scapulae and the upper fibres of is represented, C5 and C6, give rise to the anterior division innervation
trapezius, suspends the scapula; only slight activity is sufficient to to pectoralis major (thus, preaxial or predominantly flexor muscles)
support the unloaded arm. The more extensive lower insertion pulls the and the posterior division innervation (thus, postaxial or predomi
inferior scapular angle forwards around the thorax, assisting trapezius nantly extensor muscles) to deltoid. Similarly, coracobrachialis (a flexor
in upward rotation of the bone, an action that is essential to raising the and adductor of the abducted arm) is innervated through the anterior


arm above the head. In the initial stages of abduction, serratus anterior division of C5, 6 and (predominantly) 7 segmental levels, while latis
helps other muscles to fix the scapula, so that deltoid acts effectively on simus dorsi is innervated through the posterior division of C6, 7 and
the humerus and not the scapula. While deltoid is raising the arm to a 8 (predominantly C7). These are examples of the movements of a joint,
right angle with the scapula, serratus anterior and trapezius are simul rather than individual muscles, being subserved in a biologically effi
taneously rotating the scapula; the combination allows the arm to be cient manner by the minimum number of spinal segmental levels
raised to the vertical. To effect this upward rotation of the scapula, required to achieve the aim of positioning the elbow in space, while
forward pull on the inferior angle by the lower digitations of serratus maintaining subtlety in effect.
anterior is coupled with an upward and medial pull on the lateral end
Pectoralis major
of the clavicle and acromion by the upper fibres of trapezius, and a
downward pull on the base of the scapular spine by the lower fibres of Attachments Pectoralis major (Fig. 48.27) is a thick, fanshaped
trapezius. Conversely, slow downward scapular rotation, assisted by muscle. It arises from the anterior surface of the sternal half of the
gravity, is achieved by controlled lengthening of these muscles. More clavicle (clavicular head); half the breadth of the anterior surface of the
powerful downward rotation requires balanced contraction of the upper sternum down to the level of the sixth or seventh costal cartilage
fibres of serratus anterior, levator scapulae, rhomboids, pectoralis minor (sternal head); the first to the seventh costal cartilages (first and seventh
and the middle part of trapezius. When weights are carried in front of often omitted); the sternal end of the sixth rib; and the aponeurosis of
the body, serratus anterior prevents backward rotation of the scapula. external oblique (rectus head). The clavicular fibres are usually sepa


Electromyography shows that serratus anterior is not active in normal rated from the sternal fibres by a slight cleft. The muscle converges to
human respiration. This may not apply to laboured respiration, e.g. a flat tendon, approximately 5 cm wide, that is attached to the lateral
Lateral cord, brachial plexus Fig. 48.27 The left deltopectoral groove,
Medial cord,
brachial plexus Posterior cord, brachial plexus dissected to show the clavipectoral fascia and
Clavicle Acromial thoraco-acromial axis. (With permission from
anastomosis Waschke J, Paulsen F (eds), Sobotta Atlas of
Subclavian artery Acromion Human Anatomy, 15th ed, Elsevier, Urban &
Fischer. Copyright 2013.)
Deltoid,
clavicular part
Subclavian vein
Deltoid,
Subclavius acromial part
Clavipectoral fascia
Cephalic vein
Lateral pectoral nerve
Thoraco-acromial artery,
pectoral branch
Pectoralis major,
clavicular head
Pectoralis major,
sternocostal head


Shoulder girdle and arm
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lip of the intertubercular sulcus of the humerus. The tendon is bilami components of that muscle from the anterior aspect of the fifth, sixth
nar. The thicker anterior lamina is formed by fibres from the manu and seventh ribs and their costal cartilages, and in the same plane as
brium, joined superficially by clavicular fibres and deeply by fibres pectoralis minor.
from the sternal margin and the second to fifth costal cartilages. Cla
vicular fibres may be prolonged into the tendon of deltoid. The pos Deltoid
terior lamina receives fibres from the sixth (and, often, seventh) costal Attachments Deltoid is a thick, curved triangle of muscle. It arises
cartilages, sixth rib, sternum, and aponeurosis of external oblique. from the anterior border and superior surface of the lateral third of the
Costal fibres join the lamina without twisting. Fibres from the sternum clavicle, the lateral margin and superior surface of the acromion, and
and aponeurosis curve around the lower border, turning successively the lower edge of the crest of the scapular spine (other than its smooth,
behind those above them, which means that this part of the muscle is medial, triangular surface) (see Figs 48.26, 48.27). The fibres converge
twisted so that the fibres that are lowest at their medial origin are inferiorly to a short, substantial tendon that is attached to the deltoid
highest at their attachment on the humerus. The posterior lamina tubercle on the lateral aspect of the midshaft of the humerus. Anterior
reaches higher on the humerus than the anterior, and gives off an and posterior fibres converge directly to this tendon. The intermediate
expansion that covers the intertubercular sulcus and blends with the part is multipennate; four intramuscular septa descend from the
capsular ligament of the shoulder joint. An expansion from the deepest acromion to interdigitate with three septa ascending from the deltoid
part of the lamina lines the intertubercular sulcus at its linear insertion; tubercle. The septa are connected by short muscle fibres that provide


another expansion descends from its lower border into the deep fascia powerful traction (Leijnse et al 2008). The fasciculi are large, producing
of the upper arm. a coarse longitudinal striation. The muscle surrounds the glenohumeral
The rounded lower border of pectoralis major forms the anterior articulation on all sides, except inferomedially, giving the shoulder its
axillary fold and becomes conspicuous in abduction against rounded profile. In contraction, its borders are easily seen and felt. The
resistance. tendon gives off an expansion into the brachial deep fascia that may
reach the forearm.
Variants The abdominal slip from the aponeurosis of external oblique
is sometimes absent. The number of costal attachments and the extent Variants Deltoid may fuse with pectoralis major or may receive addi
to which the clavicular and costal parts are separated vary. Right and tional slips from trapezius, the infraspinous fascia or the lateral scapular
left muscles may decussate across the sternum. A superficial vertical slip, border. Teres minor shares a common innervation and could be con
or slips, may ascend from the lower costal cartilages and rectus sheath sidered as a fourth, posteroinferior, part of deltoid.
to blend with sternocleidomastoid or to attach to the upper sternum
or costal cartilages. This is sternalis (rectus sternalis). Relations The skin, superficial and deep fasciae, platysma, lateral
supraclavicular and upper lateral brachial cutaneous nerves are all
Relations Skin, superficial fascia, platysma, medial and intermediate superficial. The coracoid process, coracoacromial ligament, subacro
supraclavicular nerves, breast tissue and deep fascia are all anterior. The mial bursa, tendons of pectoralis minor, coracobrachialis, both heads
sternum, ribs and costal cartilages, clavipectoral fascia, subclavius, pec of biceps brachii, pectoralis major, subscapularis, supraspinatus, infra
toralis minor, serratus anterior, external intercostal muscles and mem spinatus, teres minor, long and lateral heads of triceps, circumflex


branes are all posterior. Pectoralis major forms the superficial layer of humeral vessels, axillary nerve, and the surgical neck and upper shaft
the anterior axillary wall, and hence lies anterior to the axillary vessels of the humerus, including both tubercles, are all deep. The anterior
and nerves and the upper parts of biceps brachii and coracobrachialis. border of deltoid is separated from pectoralis major proximally by the
Its upper border is separated from deltoid by the infraclavicular fossa, infraclavicular fossa, which contains the cephalic vein and deltoid
which contains the cephalic vein and deltoid branch of the thoraco branches of the thoracoacromial artery; distally, these muscles are in
acromial artery. Pectoralis major is separated from latissimus dorsi on contact. The posterior border of deltoid overlies infraspinatus and
the medial axillary wall but the two muscles converge as they approach triceps.
the lateral axillary wall; the floor of the intertubercular sulcus lies
between their attachments. Vascular supply Deltoid is supplied by acromial and deltoid
branches of the thoracoacromial artery; the anterior and posterior
Vascular supply Pectoralis major is supplied by one dominant vas circumflex humeral arteries; subscapular artery; and the deltoid branch
cular pedicle from the pectoral branch of the thoracoacromial axis, of profunda brachii.
supplemented by several smaller secondary segmental vessels from the
deltoid and clavicular branches of the thoracoacromial axis, and per Innervation Deltoid is innervated by the axillary nerve, C5 and 6.
forating branches of the internal thoracic arteries and superior and
lateral thoracic arteries. Actions Different parts of the muscle can act independently, as well
as together. Anterior fibres assist pectoralis major in drawing the arm
Innervation Pectoralis major is supplied through the medial and forwards and rotating it medially. Posterior fibres act as external
lateral pectoral nerves. Fibres for the clavicular part are from C5 and 6; rotators, and act with latissimus dorsi and teres major in drawing the


those for the sternocostal part are from C7, 8 and T1. arm backwards (into extension). The posterior fibres of deltoid
provide up to 80% of the external rotation power of the arm when
Actions The two parts of pectoralis major can act separately or elevated into the plane of the scapula. The multipennate, acromial,
together. The whole muscle assists adduction and medial rotation of part of deltoid is a strong abductor; aided by supraspinatus, it abducts
the humerus against resistance. It swings the extended arm forwards the arm until the inferior joint capsule is tight. Movement takes
and medially, its clavicular part acting with the anterior fibres of deltoid place in the plane of the body of the scapula, which is the only way
and coracobrachialis; the sternocostal part is relaxed. The opposite that scapular rotation can be fully effective in raising the arm above
movement is usually aided by gravity. When it is resisted, the sterno the head. In true abduction, acromial fibres contract strongly, while
costal part acts together with latissimus dorsi, teres major and the clavicular and posterior fibres prevent departure from the plane of
posterior fibres of deltoid; the clavicular part is relaxed. With the raised motion. In the early stages of abduction, traction by deltoid is upward,
arms fixed, e.g. gripping a branch, the same combination of muscles but the humeral head is prevented from translating upward by the
draws the trunk up and forwards. Pectoralis major is active in deep synergistic centralizing effect of the rotator cuff muscles (supraspina
inspiration. tus, subscapularis, infraspinatus and teres minor). Electromyography
suggests that deltoid contributes little to medial (internal) or lateral
(external) rotation but confirms that it takes part in most other shoul
Testing To test the clavicular head, the abducted arm is flexed against
der movements.
resistance. To test the sternocostal head, the arm is adducted against
resistance.
Testing Deltoid can be seen and felt to contract when the arm is
Poland’s syndrome abducted against resistance in the scapular plane. Since this motion can


also be achieved by supraspinatus, a more specific test for the activity
of deltoid is to assess extension against resistance with the arm in 30°
Available with the Gray’s Anatomy e-book
abduction in the scapular plane: this reduces the confounding effect of
latissimus dorsi and triceps as extensors of the adducted arm. Subtle
Chondro-epitrochlearis Chondroepitrochlearis is a rare extra weakness can be determined using the deltoid lag sign (Hertel et al
‘head’ of pectoralis major, arising deep to the sternal and rectus 1998).


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Poland’s syndrome is a rare congenital anomaly, in which there is
hypoplasia of the thoracic chest wall muscles and ipsilateral hypoplasia
of the arm and hand. It occurs in approximately 1 : 50,000 live births.
The major clinical feature is absence of the sternocostal head of
pectoralis major and all of pectoralis minor. In addition, there may be
hypoplasia of latissimus dorsi, serratus anterior, external oblique,
supraspinatus, infraspinatus, deltoid and the intercostal muscles, and
hypoplasia of the hemithorax and ribs. Hypoplasia affecting the arm
ranges from syndactyly to symbrachydactyly and ectrodactyly. The
second, third and fourth fingers are the most affected; the wrist, forearm,
upper arm and scapula are variably involved. There may be ipsilateral
breast hypoplasia and absent nippleareolar complex.
The aetiology is unclear. It has been suggested that the condition is
caused by disruption of lateral plate mesenchyme 2–4 weeks after ferti
lization, or by disruption of the arterial blood supply to the subclavian
vessels during the sixth and seventh weeks of embryonic life.
The muscle has an extensive attachment to the lateral crest of the
intertubercular sulcus, the medial intermuscular septum and the medial
epicondylar ridge. It is innervated by branches of the lateral pectoral
nerve that perforate pectoralis minor or pass to the muscle in the plane
between pectoralis minor and major. It is noted as a pterygium deep to
the anterior axillary wall with a sharply defined inferior border in the
axilla, made more noticeable by flexion and medial rotation against
resistance with the arm elevated into the scapular plane. With the arm
in the elevated position, contraction of the muscle causes a retropulsion
of the glenohumeral joint, a rare cause of posterior glenohumeral
instability.


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Coracobrachialis the medial head of triceps and brachialis (Fig. 48.28). Accessory slips
may be attached to the lesser tubercle, medial epicondyle or medial
Coracobrachialis is the most medial of the three anterior compartment
intermuscular septum.
muscles of the arm. It has a common origin with the short head of
biceps brachii. In turn, the short head of biceps shares a common distal
attachment with the long head of biceps. The three anterior compart Relations Coracobrachialis forms an inconspicuous rounded ridge
ment muscles, therefore, form a single functional group that brings the on the upper medial side of the arm; pulsation of the brachial artery
supinated hand into flexion and medial rotation, towards the face. can be felt and often seen in the depression behind it. The muscle is
perforated and supplied by the musculocutaneous nerve. Anteriorly, it
Attachments Coracobrachialis arises from the deep surface of the is related to pectoralis major above and, at its humeral insertion, to the
apex of the coracoid process, deep to the tendon of the short head of brachial vessels and median nerve, which cross it. The tendons of sub
biceps brachii, and by muscular fibres from the proximal 5–10 cm of scapularis, latissimus dorsi, teres major, the medial head of triceps,
this tendon. It ends on an impression, 3–5 cm in length, midway along the humerus and the circumflex humeral vessels are all posterior. The
the medial border of the humeral shaft between the attachments of third part of the axillary artery and proximal parts of the median and
A
Subclavius Clavicle
Coracoid process
Deltoid
Costoclavicular ligament, trapezoid ligament Capsule of acromioclavicular joint
Costoclavicular ligament, conoid ligament Acromion
Subacromial bursa
Levator scapulae
Coraco-acromial ligament
Omohyoid, inferior belly
Coracobrachial bursa
Serratus anterior
Pectoralis minor
Rhomboid minor Biceps brachii, short head


Supraspinatus Coracobrachialis
Superior transverse scapular ligament Deltoid
Intertubercular tendon sheath
Subscapularis
Rhomboid major Pectoralis major
Latissimus dorsi, tendon
Medial border of scapula
Triceps brachii, lateral head
Biceps brachii, long head
Upper triangular space
Coracobrachialis Teres major
Serratus anterior Biceps brachii, short head
Joint capsule (axillary recess) Lower triangular space
Quadrangular space Triceps brachii, long head
B Omohyoid, inferior belly
Acromion
Levator scapulae
Subdeltoid bursa Superior angle
of scapula
Deltoid (cut) Rhomboid minor
Supraspinatus
Trapezius
Deltoid (cut)
Spine of scapula
Humerus, surgical neck
Capsule of glenohumeral joint Rhomboid major
Quadrangular space
Infraspinatus
Triceps brachii, long head
Teres minor
Triceps brachii, lateral head Upper triangular space
Teres major
Inferior angle
of scapula
Latissimus dorsi
Serratus anterior
Fig. 48.28 Deep muscles of the left shoulder girdle. A, The anterior aspect after removal of the superficial muscles. B, Posterior aspect. (With permission
from Waschke J, Paulsen F (eds), Sobotta Atlas of Human Anatomy, 15th ed, Elsevier, Urban & Fischer. Copyright 2013.)


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musculocutaneous nerves are first medial and become posterior further axillary arch, 7–10 cm in length and 5–15 mm in breadth, may some
distally; they may be partially obscured by the muscle if it is bulky. times be present; it crosses from the edge of latissimus dorsi, midway
Biceps brachii and brachialis are lateral. in the posterior fold, and passes anterior to the axillary vessels and
nerves to join the tendons of pectoralis major, coracobrachialis or the
Vascular supply One or more branches from the axillary artery pass fascia over biceps brachii. The vertebral and costal attachments of latis
deep to the lateral root of the median nerve and the musculocutaneous simus dorsi may be reduced or, in rare cases, increased. A fibrous slip
nerve to reach the deep surface of coracobrachialis. Branches from the usually passes from the tendon, near its humeral insertion, to the long
anterior circumflex humeral artery supply the deep surface of the head of triceps.
muscle. The artery accompanying the musculocutaneous nerve sends a
recurrent branch to the coracoid attachment and gives off a series of Vascular supply Latissimus dorsi is supplied by a single dominant
branches to coracobrachialis during its intramuscular course. Accessory vascular pedicle, the thoracodorsal artery, itself a continuation of the
branches from the thoracoacromial artery supply the superficial part subscapular artery. The thoracodorsal artery and its accompanying
of coracobrachialis. venae comitantes enter the muscle at a single neurovascular hilum on
its costal surface, 6–12 cm from the subscapular artery and 1–4 cm
Innervation Coracobrachialis is innervated by the musculocutaneous medial to the lateral border of the muscle. The artery gives off up to
nerve, C5, 6 and 7. three large branches to serratus anterior before dividing at, or even
before, the neurovascular hilum for latissimus dorsi. The basic pattern


Actions Deltoid and coracobrachialis insert into the humerus approx of branching is a bifurcation into lateral and medial branches. The
imately opposite each other. Coracobrachialis acts as an antagonist to larger lateral branch follows a course parallel to, and 1–4 cm from, the
the action of deltoid, particularly when the arm is in abduction and upper border of the muscle; the smaller branch diverges at an angle of
extension; it flexes the arm forwards and medially. In abduction, it acts 45° and travels medially. In a small number of cases, the artery trifur
with the anterior fibres of deltoid to resist departure from the plane of cates. This usually yields a small recurrent branch that returns to supply
motion. the proximal part of the muscle but, in some cases, it provides a third
major branch that supplies the distal part of the muscle. Occasionally,
Testing Coracobrachialis can be tested by palpating its fibres during the lateral branch gives off a further collateral to serratus anterior. The
adduction and medial rotation of the flexed shoulder against resistance. major branches give off 5–9 longitudinal branches that travel distally,
Alternatively, the muscle can be palpated during forceful depression of parallel with the muscle fibres. Musculocutaneous perforators arising
the elbow against resistance or with the arm by the side. from these vessels supply the overlying skin.
In addition to the dominant vascular pedicle, latissimus dorsi is
Latissimus dorsi
supplied inferiorly by several smaller, secondary, segmental vascular
Attachments Latissimus dorsi is a large, flat, triangular muscle that pedicles. These are dorsal perforating arteries derived from the ninth,
sweeps over the lumbar region and lower thorax, and converges to a tenth and eleventh posterior intercostal arteries and the first, second
narrow tendon (see Fig 48.26). It arises by tendinous fibres from the and third lumbar arteries. They all enter the muscle on its deep surface
spines of the lower six thoracic vertebrae anterior to trapezius; from the and anastomose within the muscle with branches of the thoracodorsal
posterior layer of thoracolumbar fascia, by which it is attached to the artery.
spines and supraspinous ligaments of the lumbar and sacral vertebrae;


and from the posterior part of the iliac crest. It also springs by muscular Innervation Latissimus dorsi is supplied by the thoracodorsal nerve,
fibres from the posterior part (outer lip) of the iliac crest lateral to from the posterior cord of the brachial plexus, C6, 7 and 8 (predomi
erector spinae, and by fleshy slips from the three or four lower ribs, nantly C7). This nerve runs in the neurovascular pedicle and divides
interdigitating with external oblique (see Fig. 61.6). From this extensive approximately 1.5 cm proximal to the point of bifurcation or trifurca
attachment, fibres pass laterally with different degrees of obliquity (the tion of the thoracodorsal artery. The neural and vascular branches travel
upper fibres are nearly horizontal, the middle oblique, and the lower together and so the pattern of branching of the nerve follows that of
almost vertical), to form a sheet 12 or 13 mm thick that overlaps the the artery closely.
inferior scapular angle, and may attach to it. The muscle curves around
the inferolateral border of teres major to gain its anterior surface and Actions Latissimus dorsi is active in adduction, extension and, espe
ends as a flattened tendon, up to 7 cm long, anterior to the tendon of cially, in medial rotation of the humerus. Humeral adduction and
teres major. It is attached to the floor of the intertubercular sulcus of extension are most powerful when the initial position of the arm is one
the humerus with an expansion to the deep fascia (Dancker 2013). The of partial abduction or flexion, or a combination of the two. With the
attachment extends higher on the humerus than that of teres major. As sternocostal part of pectoralis major and teres major, it adducts the
the muscle curves round teres major, the fasciculi rotate around each raised arm against resistance. When the arms are raised above the head,
other, so that fibres that originate lowest at the midline insert highest as in climbing, it pulls the trunk upwards and forwards. It takes part in
on the humerus, and fibres that originate highest at the midline insert all violent expiratory efforts, such as coughing or sneezing; this is


lowest on the humerus. A bursa sometimes occurs between the muscle readily confirmed by palpation. Electromyography suggests that latis
and the inferior scapular angle. The tendons of latissimus dorsi and simus dorsi aids deep inspiration, but it is also active towards the end
teres major are united at their lower borders but separated by a bursa of forcible expiration, e.g. when blowing a sustained note on a musical
near their humeral attachments. instrument. When the arm is elevated, the stretched fibres of latissimus
Latissimus dorsi and teres major together form the posterior axillary dorsi press on the inferior scapular angle (to which it may also be
fold. When the arm is adducted against resistance, this fold is accentu attached), keeping it in contact with the chest wall. Despite this range
ated, and the whole inferolateral border of latissimus dorsi can be of actions, surgical transposition of the muscle does not appear to
traced to its attachment to the iliac crest. The radial nerve and the produce any serious restriction of normal activity.
branch or branches it supplies to the medial head of triceps are close
anterior relations of the tendon of the latissimus dorsi, 3–5 cm medial Testing Latissimus dorsi is palpated when the abducted arm is
to the shaft of the humerus, before the radial nerve traverses the lower adducted against resistance and can be felt to contract during coughing.
triangular space and passes into the posterior compartment of the arm
(see quadrangular and triangular spaces below).
The lower, lateral margin of latissimus dorsi is usually separated MUSCLES OF CONCAVITY COMPRESSION
from the posterior border of external oblique by the lumbar triangle.
The base of this small triangle is the iliac crest and its floor the internal The function of the rotator cuff muscles is to generate a concavity com
oblique; it should not be confused with the triangle of auscultation, pressive force in all positions of the arm at the shoulder. The term
medial to the scapula, which is bounded above by trapezius, below by ‘rotator cuff’ is conventionally taken to mean the tendinous parts of the


latissimus dorsi and laterally by the medial border of the scapula. Part four rotator cuff muscles: subscapularis, supraspinatus, infraspinatus
of rhomboid major is exposed in the triangle. If the scapulae are drawn and teres minor. Since teres minor, parts of infraspinatus and most of
forwards, by folding the arms across the chest, and the trunk is bent subscapularis do not have tendons, this use of the term excludes impor
forwards, parts of the sixth and seventh ribs and the interspace between tant parts of the rotator cuff apparatus. In this description, the term
them (overlying the apex of the lower pulmonary lobe) become ‘rotator cuff’ will be used to define the entire musculotendinous appa
subcutaneous. ratus that centralizes the humeral head on the glenoid. The tendons of
the rotator cuff will be referred to specifically.
Variants Latissimus dorsi commonly receives some additional fibres It is also maintained that the inferior capsule of the glenohumeral
from the scapula as it crosses the inferior scapular angle. A muscular joint is exposed as a weak part of the capsule, and so predisposed to


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injury (dislocation). However, in elevation of the arm above 90°, the Infraspinatus
bulk of teres major forms a muscular buttress to the lower part of Attachments Infraspinatus is a thick, triangular muscle that occu
the joint and, in this position, clearly draws the humeral head into the
pies most of the infraspinous fossa (see Fig. 48.28). It arises by mus
glenoid, i.e. it has a centralizing effect. Teres major is a part of the cen
cular fibres from the medial twothirds of the fossa, by tendinous
tralizing function of the rotator cuff, and should be considered along
fibres from ridges on its surface and from the deep surface of the
with the conventional definition of the rotator cuff.
infraspinous fascia, which separates it from teres major and minor. Its
The mechanism of the rotator cuff has been likened to that of the
fibres converge to a tendon that glides under the lateral border of the
fibrous ‘endoskeleton’ of the heart, in which the muscular chambers are
spine of the scapula, and then passes across the posterior aspect of the
constructed around the fibrous architecture of the valvular system, and
capsule of the shoulder joint to be attached to the middle facet on the
muscle contraction is centralized on this fibrous support. The muscles
greater tubercle of the humerus. The tendon fuses with that of
of the rotator cuff are attached to their tendons in a similar manner:
supraspinatus immediately lateral to the thick lateral margin of the
the fibrous architecture of the tendons provides a framework for the
spine of the scapula; the tendon fibres decussate so that fibres of infra
action of the rotator cuff so that it always generates a centralizing force
spinatus can be traced to the facet for supraspinatus, and vice versa
on the glenoid (Gagey et al 1993).
(Mochizuki et al 2008). The tendon is sometimes separated from the
The muscles of the rotator cuff combine in three groups (subscapu
capsule by a bursa, which may communicate with the joint cavity. The


laris and teres major, supraspinatus and infraspinatus, and teres minor)
tendon is flattened, but is thickened in several places, reinforcing its
by virtue of their innervation. Subscapularis and teres major are
posterior aspect as it attaches to the middle facet. From this region,
innervated through the subscapular nerves (C5, 6 and 7, posterior divi
fibres passing orthog onally within the deeper substance of the tendon
sion, posterior cord); supraspinatus and infraspinatus by the supras
of infraspinatus pass forwards into supraspinatus, then pass across the
capular nerve (C5, 6, upper trunk); and teres minor by the axillary
rotator interval to subscapularis. This band of fibres is termed the
nerve (C5, 6, posterior division, posterior cord). The common origin
‘cable’ (Burkhart et al 1993); it provides the mechanical link between
of their innervation suggests a common final action, namely: the gen
the posterosuperior and anterior parts of the rotator cuff, thus ensur
eration of the centralizing compression force. In functional terms,
ing that there is intrinsic coordination of the rotator cuff mechanism.
supraspinatus and infraspinatus can be considered as one muscle on
The muscular part of infraspinatus is attached directly to the middle
the grounds that they have the same innervation and the same vascular
facet on the greater tubercle and is sometimes fused with teres minor
supply; their attachment to the scapula is a continuum broken only by
laterally, although their tendons are usually separable closer to the
the spine of scapula for the attachment of trapezius; and their actions
joint capsule.
are complementary.
Vascular supply Infraspinatus is supplied by the suprascapular and
Supraspinatus
circumflex scapular arteries.
Attachments Supraspinatus arises from the medial twothirds of the
supraspinous fossa and from the supraspinous fascia (Fig. 48.28). The Innervation Infraspinatus is innervated by the suprascapular nerve,
fibres converge, under the acromion, into a thick tendon that passes


C5 and 6.
obliquely through the muscle, crosses above the humeral head, and is
attached to the highest facet of the greater tubercle of the humerus. The Actions Infraspinatus is a lateral rotator of the humerus. Together
tendon has a posterior, flatter, component closer to the facet of attach
with supraspinatus, subscapularis and teres minor, it helps to stabilize
ment. The anterior, obliquely directed, fibres of supraspinatus are
the head of the humerus in the glenoid fossa during shoulder
inserted into the anterior aspect of the thick tendon, while the more
movements.
parallel posterior fibres are inserted into both the thick tendon and the
flatter component. The thick tendon is contiguous with the transverse Teres minor
humeral and coracohumeral ligaments; it forms an anterior pillar to Attachments Teres minor is a narrow, elongated muscle that arises
the posterosuperior part of the rotator cuff. The deep surface of the from the upper twothirds of a flattened strip on the dorsal surface of
tendon blends into the articular capsule over its distal 1 cm or so. the scapula adjoining its lateral border, and from two aponeurotic
Fibrocartilage has been described at the tendinous insertion, as in other laminae that separate it from infraspinatus and teres major (see Fig.
tendons attached to epiphysial bone. 48.28). It runs upwards and laterally. The upper fibres end in a short
tendon (which may be absent), attached to the lowest facet on the
Vascular supply Supraspinatus is supplied by the suprascapular and greater tubercle of the humerus. The lower fibres are attached directly
dorsal scapular arteries. into the humerus distal to this facet and above the origin of the lateral
head of triceps. The tendon passes across, and blends with, the lower
Innervation Supraspinatus is innervated by the suprascapular nerve, posterior surface of the capsule of the shoulder joint. Teres minor may
C5 and 6. be fused with infraspinatus.
Actions The conventional view is that supraspinatus initiates abduc Vascular supply Teres minor is supplied by the circumflex


tion of the shoulder and assists deltoid in abduction thereafter. scapular artery, which pierces the origin of the muscle as it turns
However, there is evidence that both supraspinatus and deltoid are upwards in the infraspinous fossa, and by the posterior circumflex
involved throughout the range of abduction, including initiation of humeral artery.
the movement. In complete axillary nerve lesions (complete, irrevers
ible deltoid palsy), supraspinatus, acting with other cuff muscles, can Innervation Teres minor is innervated by a branch of the axillary
initiate, regulate, achieve and maintain full abduction of the arm nerve that is given off the main trunk as it enters the quadrangular
(although endurance is limited). If supraspinatus is detached, torn or space, C5 and 6.
paralysed, and deltoid is also paralysed, investigation and surgical
exploration and repair of damaged rotator cuff tendon, muscle or Actions Teres minor acts as a lateral rotator and weak adductor of the
nerve supply is mandatory. With a functioning rotator cuff but poor humerus with the arm pendant. Together with supraspinatus, infra
deltoid, the arm is functionally adept and useful, whereas with a spinatus, subscapularis and teres major, it helps to stabilize the head of
poorly functioning rotator cuff and normal deltoid, arm function is the humerus in the glenoid fossa during shoulder movements.
potentially poor because stability of the joint is adversely compro
mised and deltoid cannot function to overcome this disability. As part Subscapularis
of the rotator cuff, supraspinatus helps to stabilize the head of the Attachments Subscapularis is a bulky, triangular muscle that fills the
humerus in the glenoid fossa during movements of the glenohumeral subscapular fossa (see Figs 48.25, 48.28A). In its medial twothirds, the
joint. With the arm dependent, even when moderately loaded, suprasp fibres are attached to the periosteum of the costal surface of the scapula.
inatus assists deltoid in prevention of downward displacement of the Other fibres arise from tendinous intramuscular septa, attached to


humerus. ridges on the bone, and from the aponeurosis that covers the muscle
and separates it from teres major and the long head of triceps. The fibres
Testing It is extremely difficult to palpate supraspinatus unless trape converge laterally into a broad tendon above, which has a thickened,
zius is thin. The tendon of supraspinatus is separated from the coraco rounded upper margin, and is attached to the lesser tubercle of the
acromial ligament, acromion and deltoid by the large subacromial humerus and the anterior part of the articular capsule, with a wide direct
bursa; when this is inflamed, abduction of the shoulder joint is painful. muscular attachment to the lower part of the lesser tubercle. The tendon
The tendon is the most frequently torn element of the musculotendi is separated from the neck of the scapula by the large subscapular bursa,
nous cuff around the shoulder joint. which may communicate with the shoulder joint.


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Variation is unusual. A separate inferior slip (subscapularis acces MUSCLES THAT COORDINATE SHOULDER AND
sorius) may pass from the lateral border of the scapula to the gleno ELBOW MOTION
humeral capsule or to the periosteum medial to the intertubercular
sulcus of the humerus. This should be distinguished from the true
The muscles of the upper arm are coracobrachialis, which acts only on
infraglenoid muscle (Staniek and Brenner 2012).
the shoulder joint; biceps and triceps, which cross both shoulder and
elbow joints; and brachialis, which acts only at the elbow joint. Coraco
Relations Subscapularis forms much of the posterior axillary wall. Its
brachialis is described on page 821.
anterior surface is apposed inferomedially to serratus anterior, the axil
lary vessels, brachial plexus and subscapular vessels and nerves, and
Anterior compartment of the arm
superolaterally to coracobrachialis and biceps. Its posterior surface is
attached to the scapula and glenohumeral capsule. Its lower border
contacts teres major and latissimus dorsi. Its upper border is contiguous Biceps brachii
with the capsule of the rotator interval; at the most lateral extent of the Attachments Biceps brachii derives its name from its two proximally
interval, the long tendon of biceps passes lateral to the attachment of attached parts or ‘heads’ (see Figs 48.15, 48.16, 48.25, 48.28A). The
subscapularis, covered by the transverse humeral ligament. short head arises by a thick, flattened tendon from the coracoid apex,
together with coracobrachialis. The long head starts within the capsule
Vascular supply Subscapularis is supplied by small branches from of the shoulder joint as a long narrow tendon, running from the sup
the suprascapular, axillary and subscapular arteries. raglenoid tubercle of the scapula at the apex of the glenoidal cavity,
where it is continuous with the glenoidal labrum. The tendon of the


Innervation Subscapularis is innervated by the upper and lower sub
long head, enclosed in a double tubular synovial sheath, arches over
scapular nerves, C5, 6 (posterior cord).
the humeral head, emerges from the joint under the transverse humeral
ligament, and descends in the intertubercular sulcus, where it is retained
Actions Subscapularis is a medial rotator of the humerus. Together
by the transverse humeral ligament and a fibrous expansion from the
with supraspinatus, infraspinatus, teres minor and teres major, it helps
tendon of pectoralis major. The two tendons lead into elongated bellies
to stabilize the head of the humerus in the glenoid fossa during shoul
that, although closely applied, can be separated to within 7 cm or so
der movements.
of the elbow joint. At this joint, they end in a flattened tendon, which
The attachment of teres major lies in direct continuity with the
is attached to the rough posterior area of the radial tuberosity; a bursa
attachment of subscapularis on the lesser tubercle. The muscles lie in
separates the tendon from the smooth anterior area of the tuberosity.
virtually the same plane as they approach the humerus, share a similar
As it approaches the radius, the tendon spirals, its anterior surface
innervation from the posterior cord of the brachial plexus, and perform
becoming lateral before being applied to the tuberosity. The tendon has
the same actions. Like the spinati, subscapularis and teres major might
a broad medial expansion, the bicipital aponeurosis, which descends
be considered as a functional unit.
medially across the brachial artery to fuse with deep fascia over the
Teres major origins of the flexor muscles of the forearm (Fig. 48.29). The tendon
Attachments Teres major is a large, thick, ovoid muscle that arises can be split without difficulty as far as the tuberosity; it can, thus, be
confirmed that its anterior and posterior layers receive fibres from the
from the oval area on the dorsal surface of the inferior scapular angle,
short and long heads, respectively.
and from the fibrous septa interposed between the muscle and teres


Occasionally, a third head arises from the superomedial part of
minor and infraspinatus (see Fig. 48.28). Its fibres ascend laterally and
brachialis and is attached to the bicipital aponeurosis and medial side
end in a short, flat tendon, 2–5 cm long, attached to the medial lip of
of the tendon of insertion. It usually lies behind the brachial artery but
the intertubercular sulcus of the humerus. The tendon lies behind that
it may consist of two slips, which descend in front of and behind the
of latissimus dorsi, from which it is separated by a bursa; the tendons
artery. Less often, other slips may spring from the lateral aspect of the
are united along their lower borders for a short distance but are readily
humerus or intertubercular sulcus.
separated.
Variants Teres major may be fused with the scapular part of latis Relations Biceps is overlapped proximally by pectoralis major and
deltoid; distally, it is covered only by fasciae and skin, and it forms a
simus dorsi, and may send a slip to join the long head of triceps or
conspicuous elevation on the front of the arm. Its long head passes
the brachial fascia.
through the shoulder joint; its short head is anterior to the joint. Dis
Vascular supply Teres major is supplied by the thoracodorsal branch tally, it lies anterior to brachialis, the musculocutaneous nerve and
of the subscapular artery on its way to latissimus dorsi and by the pos supinator. Its medial border touches coracobrachialis and overlaps the
terior circumflex humeral artery (Dancker 2013). brachial vessels and median nerve; its lateral border is related to deltoid
and brachioradialis.
Innervation Teres major is innervated by the lower subscapular nerve,
C5, 6 and 7. Vascular supply Biceps brachii is typically supplied by up to eight
vessels originating from the brachial artery in the middle third of the
Actions Despite its name, teres major has a nerve supply and action arm. These vessels pass laterally, posterior to the median nerve, and


that is distinct from teres minor. Teres major draws the humerus back divide into ascending and descending branches just before reaching the
wards and rotates it medially. Electromyographic studies are equivocal deep surface of the muscle. Smaller branches arise from the anterior
about its major role in movement, but its involvement as a contributor circumflex humeral artery and the deltoid branch of the acromial divi
to static posture and armswinging is not contested. sion of the thoracoacromial axis.
There is great variation in the arterial supply to the muscle. The main
Testing Teres major can be palpated posterior to the posterior axillary arterial supply may originate from the superior or inferior ulnar col
fold during adduction of the humerus against resistance. lateral arteries, subscapular artery, axillary artery, ulnar or radial arteries
in cases of proximal bifurcation of the brachial artery, or the profunda
Rotator cuff disease
brachii artery. There is often a single large pedicle, attending the nerve
The subacromial space is defined inferiorly by the superior surface of to biceps; injury to the muscle and musculocutaneous nerve at this level
the rotator cuff (supraspinatus and the anterior part of infraspinatus); in the arm commonly results in a fibrotic, atonic muscle with distal
superiorly by the anterior edge and inferior surface of the anterior third sensory dysfunction.
of the acromion, coracoacromial ligament and acromioclavicular joint,
forming the coracoacromial arch; and posteriorly by the posterior wall Innervation Biceps brachii is innervated by the musculocutaneous
of the subacromial bursa. It is occupied by the subacromial bursa, lined nerve, C5 and 6, with separate branches passing to each belly.
by synovial membrane, that extends anterolaterally under deltoid as the
subdeltoid bursa, and which facilitates movement of the rotator cuff Actions Biceps brachii is a powerful supinator, especially in rapid or
under the coracoacromial arch. The upper surface of the rotator cuff resisted movements. It flexes the elbow – most effectively, with the


normally impinges, without symptoms, under the coracoacromial arch forearm supinated – and acts, to a slight extent, as a flexor of the
when the humerus is abducted, flexed and medially rotated. If the upper shoulder joint. The long head helps to check upward translation of
surface of the rotator cuff is damaged, the bursa is thickened or inflamed, the humeral head during contraction of deltoid, in synergy with the
or the undersurface of the coracoacromial arch is rough, then the action of the rotator cuff. It is attached, via the bicipital aponeu
impingement can become abrasive: this is the painful condition called rosis, to the posterior border of the ulna, the distal end of which
‘impingement syndrome’. is drawn medially in supination. When the elbow is flexed against


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Pain is generated during abduction of the arm in the scapular plane;
typically, an arc of pain is experienced (between 60° and 120° of eleva
tion, the impingement arc). Rotator cuff disease is a painful condition
with a multifactorial aetiology, in which severe or chronic impingement
of the rotator cuff tendons on the undersurface of the coracoacromial
arch is often a significant factor. The supraspinatus tendon is anatomi
cally affected most by the impingement, which coincides with an area
of reduced vascularity in this tendon. When associated with a tendin
opathy from agerelated degenerative changes within the tendon,
impingement may be associated with partial or complete tears of the
cuff. Clinically, this condition causes tenderness over the anterior
portion of the acromion, and pain that typically occurs on abducting
the shoulder between 60° and 120° (the painful arc).
Lowering the hand under the influence of gravity by extension at the
elbow calls for controlled lengthening of biceps brachii. This is an
example of a habitual movement in which muscle tension increases
despite increasing length. (This is ‘eccentric’ loading of a muscle; during
such loading, the muscle–tendon junction is at greater risk of rupture.
‘Concentric’ loading occurs when the muscle shortens as tension
increases, see p. 114.) As the hand descends and the elbow extends, the
vertical through the centre of gravity of the forearm is carried further
from the fulcrum of movement; therefore, the turning moment exerted
by the load increases and must be matched by an increase in the
moment exerted by the muscle.


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Suprascapular nerve Axillary artery A
Subscapular nerves Lateral cord of brachial plexus Biceps brachii Cephalic vein
Medial cord of Brachial artery Musculocutaneous
brachial plexus Coracobrachialis nerve
Posterior cord of Median nerve Brachialis
brachial plexus Pectoralis minor
Subscapularis Musculocutaneous Basilic vein Vena comitans
Posterior nerve
circumflex Medial cutaneous Humerus
humeral Deltoid nerve of forearm
artery Superior ulnar
Radial nerve
collateral artery
Pectoralis
Teres major
major Profunda brachii
Ulnar nerve artery
Subscapular
artery
Thoracodorsal
nerve Triceps
Brachial vein
Latissimus dorsi
Medial cutaneous
nerve of arm
Brachial artery
Medial cutaneous and median nerve Cephalic vein Brachialis
Biceps
nerve of forearm
brachii,
Anterior circumflex short
humeral artery and long
heads
Triceps brachii, long head
Median
Radial nerve
nerve
Profunda brachii artery
Ulnar nerve
Triceps brachii, medial head
Medial intermuscular septum
Musculocutaneous
nerve
Brachial artery
Bicipital aponeurosis
Fig. 48.29 Muscles, vessels and nerves of the left upper arm, anterior
aspect. (With permission from Waschke J, Paulsen F (eds), Sobotta Atlas
of Human Anatomy, 15th ed, Elsevier, Urban & Fischer. Copyright 2013.)
resistance, the tendon of insertion and bicipital aponeurosis become B
conspicuous.
Testing With the forearm supinated, biceps brachii can be tested by Basilic vein Ulnar nerve Radial artery
and nerve
palpating its fibres during elbow flexion against resistance.
Fig. 48.30 A, A transverse section through the left arm, a little below the
Brachialis middle of the shaft of the humerus. B, A magnetic resonance imaging


Attachments Brachialis arises from the lower half of the anterior (MRI) scan at a similar level.
surface of the shaft of the humerus, starting on either side of the inser
tion of deltoid, and extending distally to within 2.5 cm of the cubital
articular surface (Fig. 48.30). It also arises from the intermuscular septa, artery distal to the site of origin of the superior ulnar collateral artery
more from the medial than the lateral, since it is separated distally from and travels laterally to enter the anterior surface of the upper third of
the lateral intermuscular septum by brachioradialis and extensor carpi the muscle. The inferior main artery originates either from the superior
radialis longus. Its fibres converge to a thick, broad tendon that is ulnar collateral artery or directly from the brachial artery, and enters the
attached to the ulnar tuberosity and to a rough impression on the midportion of the muscle. The accessory arteries are small and variable
anterior aspect of the coronoid process (see Fig. 49.5). in number, origin and course. They can arise from the brachial artery,
Brachialis may be divided into two or more parts. It may be fused the superior and inferior ulnar collateral arteries, or the profunda
with brachioradialis, pronator teres or biceps. In some cases, it sends a brachii artery. The fact that brachialis has a greater vascular supply than
tendinous slip to the radius or to the bicipital aponeurosis. biceps brachii suggests that its metabolic demands are greater; brachia
lis is the prime flexor of the forearm at the elbow, while biceps has more
Relations Biceps, the brachial vessels and the musculocutaneous and subtle actions on the shoulder and elbow, coordinating the two joints
median nerves are anterior. The humerus and the capsule of the elbow while positioning the hand in space.
joint are posterior. Pronator teres and the medial intermuscular septum,
which separates it from triceps and the ulnar nerve, are medial. The Innervation Brachialis is innervated by at least two branches. The


radial nerve, radial recurrent and radial collateral arteries, brachioradia musculocutaneous nerve (C5 and 6) supplies a large medial part of the
lis and extensor carpi radialis longus are all lateral. muscle, and the radial nerve (C7) supplies a small lateral part. This
arrangement is consistent (Oberlin et al 1994).
Vascular supply The blood supply to brachialis typically consists of
two main arteries (superior and inferior), supplemented by a system of Action Brachialis is a flexor of the elbow joint with the forearm either
accessory arteries. The superior main artery originates from the brachial prone or supine, whether or not the movement is resisted.


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Testing Brachialis can be tested by palpating its fibres during elbow Articularis cubiti probably draws up the posterior part of the capsule of
flexion against resistance. the elbow joint during extension of the forearm. In forceful supination
of the semiflexed forearm, involving contraction of both supinator and
Posterior compartment of the arm biceps brachii, triceps contracts synergistically to maintain the semi
flexed position.
Triceps
Testing Triceps can be tested by palpating its fibres during elbow
Attachments Triceps fills most of the extensor compartment of the extension against resistance.
upper arm (see Figs 48.28–48.30). It has three heads (long, lateral and
Quadrangular and triangular spaces
medial), from which it takes its name.
The long head arises by a flattened tendon from the infraglenoid The quadrangular space (quadrilateral space; foramen of Velpeau) is
tubercle of the scapula, blending above with the glenohumeral capsule. more a horizontal cleft or tunnel than a vertical space; it has defined
Its muscular fibres descend medial to the lateral head and superficial boundaries. Anteriorly, the space is bounded by subscapularis, the
to the medial head, and join them to form a common tendon. The capsule of the shoulder joint and teres minor superiorly, teres major
lateral head arises by a flattened tendon from a narrow, linear, oblique inferiorly, the long head of triceps medially and the surgical neck of the
ridge on the posterior surface of the humeral shaft, and from the lateral humerus laterally. Posteriorly, the quadrangular space is bounded above
intermuscular septum. The origin on the humerus ascends with varying by teres minor. The axillary nerve and the posterior circumflex humeral
obliquity from its lateral border above the radial groove and behind the artery and vein pass obliquely through the space (see Figs 48.33, 48.47).
deltoid tuberosity to the surgical neck medial to the insertion of teres There are two triangular spaces (see Figs 48.28, 48.47). The upper


minor. These fibres also converge to the common tendon. The medial triangular space is bounded above by subscapularis anteriorly, teres
head, which is overlapped posteriorly by the lateral and long heads, has minor pos teriorly, teres major inferiorly and the long head of triceps
a particularly extensive origin. It is attached to the entire posterior laterally. The circumflex scapular vessels pass through this space. The
surface of the humeral shaft, below the radial groove from the insertion lower triangular space (the triangular interval) is bounded above by
of teres major to within 2.5 cm of the trochlea; the medial border of subscapularis anteriorly, teres major posteriorly, the long head of triceps
the humerus; the medial intermuscular septum; and the lower part of medially and the humerus laterally. The radial nerve and the profunda
the lateral intermuscular septum. Some muscular fibres reach the olec brachii vessels pass through this space.
ranon directly; the rest converge to the common tendon (Keener et al
2010). Some fibres from the medial head attach to the posterior capsule
VASCULAR SUPPLY AND LYMPHATIC DRAINAGE
of the elbow joint, like those of articularis genus in the knee; these fibres
are the articularis cubiti.
The tendon of triceps begins near the middle of the muscle. It has ARTERIES
two laminae organized in a similar arrangement to the tendon of the
gastrocnemii and soleus in the posterior compartment of the leg. The Dorsal scapular artery
superficial lamina in the lower half of the superficial parts of the muscle
forms an aponeurotic layer to which the deep fascia of the arm is adher In the majority of cases, the dorsal scapular artery arises from the third,
ent; the other lamina is more vertical. After receiving the muscle fibres, or less often the second, part of the subclavian artery. It passes laterally
the two layers unite above the elbow and are attached, for the most through the trunks of the brachial plexus in front of scalenus medius
part, to the upper surface of the olecranon. On the lateral side, a band and then deep to levator scapulae to reach the superior scapular angle.


of fibres continues down over anconeus to blend with antebrachial Here, it descends with the dorsal scapular nerve under the rhomboids
fascia. along the medial border of the scapula to the inferior angle. It supplies
the rhomboids, latissimus dorsi and the inferior portion of trapezius
Relations The long head of triceps descends between teres minor and and the skin over the inferomedial aspect of trapezius via musculo
major, dividing the wedgeshaped interval between them and the cutaneous perforators. It anastomoses with the suprascapular and sub
humerus into triangular and quadrangular spaces (Fig. 48.28). The scapular arteries and with posterior branches of some posterior
lateral head of triceps forms an elevation, parallel and medial to intercostal arteries. It sends a small branch to scalenus anterior; some
the posterior border of deltoid, which stands out prominently when times, this arises directly from the subclavian artery.
the elbow is actively extended. The mass that lies medial to it, and that
disappears under deltoid, is the long head. Variants About onethird of the superficial cervical and dorsal scapu
lar arteries arise as a common vessel – the transverse cervical artery –
Vascular supply The blood supply to triceps is mainly from the from the thyrocervical trunk, which then divides into a superficial and
profunda brachii artery and the superior ulnar collateral artery, with an a deep branch (superficial cervical and dorsal scapular arteries, respec
accessory supply from the posterior circumflex humeral artery. The tively) (see Figs 26.1A, 48.31). In this case, the dorsal scapular artery
medial head of triceps is supplied on its anterior surface by two or three arises near the superior border of the scapula; it passes laterally, anterior
branches from the superior ulnar collateral artery. The posterior surface to the brachial plexus and then posterior to levator scapulae.
is supplied by a large proximal branch from the profunda brachii that
passes medially anterior to the radial nerve. The long head of triceps is Suprascapular artery
supplied on its anterior surface by two arteries, one arising from the


axillary artery anterior to the tendon of latissimus dorsi and the other The suprascapular artery usually arises from the thyrocervical trunk of
arising from either the brachial artery or the superior ulnar collateral the subclavian artery, although it may arise from the third part of the
artery. The posterior surface receives a recurrent branch from the pos subclavian artery (see Fig. 29.7A). It first descends laterally across scal
terior circumflex humeral artery immediately after it has traversed the enus anterior and the phrenic nerve, posterior to the internal jugular
quadrangular space. The lateral surface receives a number of small vein and sternocleidomastoid, then crosses anterior to the subclavian
branches from the profunda brachii artery in its distal portion. The artery and brachial plexus, posterior and parallel with the clavicle, sub
lateral head of triceps is primarily supplied by branches of the profunda clavius and the inferior belly of omohyoid, to reach the superior border
brachii, with an additional supply from a branch of the posterior cir of the scapula. Here, it passes above (sometimes, under) the superior
cumflex humeral artery. transverse ligament, separating it from the suprascapular nerve, and
enters the supraspinous fossa (Fig. 48.31, see Fig. 48.33), where it lies
Innervation Triceps is innervated by branches from the radial nerve, on the bone, and supplies supraspinatus. It descends behind the scapu
C6 (lateral head), 7 (long head) and 8 (medial head); there are separate lar neck, and passes through the spinoglenoid notch deep to the inferior
branches for each head. transverse ligament to gain the deep surface of infraspinatus, where it
anastomoses with the circumflex scapular and deep branch of the trans
Actions Triceps is the major extensor of the forearm at the elbow joint. verse cervical artery. Its muscular branches supply sternocleidomastoid,
The medial head is active in all forms of extension, whereas the lateral subclavius and infraspinatus. It also gives off a suprasternal branch that


and long heads are minimally active, except in extension against resist crosses the sternal end of the clavicle to supply the skin of the upper
ance, as in thrusting or pushing or supporting body weight on the hands thorax, and an acromial branch that pierces trapezius to supply the skin
with the elbows semiflexed. When the flexed arm is extended at the over the shoulder. This last branch anastomoses with the thoraco
shoulder joint, the long head may assist in drawing back and adducting acromial and posterior circumflex humeral arteries.
the humerus to the thorax. The long head supports the lower part of As the suprascapular artery passes over the superior transverse liga
the capsule of the shoulder joint, especially when the arm is raised. ment, it gives off a branch that enters the subscapular fossa beneath


Vascular supply and lymphatic drainage
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Transverse cervical artery First rib Fig. 48.31 The scapular anastomosis, left side.
(With permission from Drake RL, Vogl AW, Mitchell
Superficial cervical artery
Suprascapular artery Left common A (eds), Gray’s Anatomy for Students, 2nd ed,
carotid artery Elsevier, Churchill Livingstone. Copyright 2010.)
Clavicle Thyrocervical trunk
Subscapular artery Left subclavian
artery
Anterior circumflex
humeral artery Axillary artery
Dorsal scapular
Posterior circumflex
artery (Deep branch
humeral artery
of transverse
Circumflex scapular cervical artery)
artery
Profunda brachii
artery
Brachial artery
Fig. 48.32 Axillary angiograms. A, View with the
arm by the side. B, View with the arm elevated.
B
A
subscapularis and anastomoses with the subscapular artery and the elevated above this, and convex upwards and laterally when the arm is
deep branch of the transverse cervical artery. It also supplies the by the side (Fig. 48.32). At first deep, it subsequently becomes super
acromioclavicular and glenohumeral joints, the clavicle and the scapula. ficial, when it is covered only by the skin and fasciae. Pectoralis minor
crosses it and so divides it into three parts, which are proximal, poste
Angiomyosomes
rior and distal to the muscle.
Available with the Gray’s Anatomy e-book Relations of the first part
The skin, superficial fascia, platysma, supraclavicular nerves, deep fascia,
Supraclavicular artery clavicular fibres of pectoralis major and the clavipectoral fascia, lateral
pectoral nerve and the loop of communication between the lateral and
medial pectoral nerves, and the thoracoacromial and cephalic veins are
This small vessel arises from either the transverse cervical or superficial
all anterior. The first intercostal space and external intercostal, first and
cervical artery. It pierces the deep fascia just superior to the clavicle and
second digitations of serratus anterior, long thoracic and medial pecto


anterior to trapezius, and supplies an area of skin over the lateral end
ral nerves, and the medial cord of the brachial plexus are all posterior.
of the clavicle.
The posterior cord of the brachial plexus is lateral and the axillary vein
is anteromedial. The first part is enclosed with the axillary vein and
Axillary artery
brachial plexus in a fibrous axillary sheath, which is continuous with
the prevertebral layer of the deep cervical fascia.
The axillary artery, a continuation of the subclavian artery, begins at the
outer border of the first rib and ends nominally at the inferior border Relations of the second part
of teres major, where it becomes the brachial artery (see Fig. 48.31). Its The skin, superficial and deep fascia, and pectoralis major and minor
direction varies with the position of the limb; it is almost straight when are all anterior. The posterior cord of the brachial plexus and the areolar
the arm is raised at right angles, concave upwards when the arm is tissue between it and subscapularis are posterior. The axillary vein is


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Two branches of the subclavian artery perfuse the dorsal scapular sus
pension and medial motion muscles (the dorsal scapular artery), the
posterosuperior rotator cuff muscles (the suprascapular artery) and
the clavicle. These vessels correspond to the equivalent innervation for
the same muscles. In this sense, innervation and angiomyotomes cor
respond. Pain afferents from the muscles, mostly small, unmyelinated
axons, travel in the nerves; ischaemic (‘fatiguerelated’) pain from these
three groups of dorsal muscles is felt as a diffuse, burning sensation in
the same region as the vascular supply, without radiation or referral,
and without respite during rest for a characteristic period, somewhat
equivalent to the period over which the symptoms of a chronic ischae
mic muscular compartment syndrome may resolve. The suprascapular
artery supplies a muscular compartment that is contained in a well
defined and relatively restricting fascia; it is, therefore, not a surprise
that the ischaemic (‘fatiguerelated’) pain generated in this compart
ment may present earlier and be more persistent than elsewhere in
muscles less well contained by fascial sheaths.


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medial, separated from the artery by the medial cord of the brachial border of pectoralis major to the breast. In both males and females, it
plexus and the medial pectoral nerve. The lateral cord of the brachial gives off cutaneous branches that pass around the lateral border of
plexus is lateral, separating the artery from coracobrachialis. The cords pectoralis major to supply the skin in this region.
of the brachial plexus thus surround the second part on three sides,
with the dispositions implied by their names, and separate it from the Subscapular artery
vein and adjacent muscles. The subscapular artery is the largest branch of the axillary artery (see
Figs 48.31, 48.47). It usually arises from the third part of the axillary
Relations of the third part artery at the distal (inferior) border of subscapularis, which it follows
Pectoralis major and, distal to the muscle, skin and fasciae are anterior. to the inferior scapular angle, where it anastomoses with the lateral
The lower part of subscapularis and the tendons of latissimus dorsi and thoracic and intercostal arteries and the deep branch of the transverse
teres major are posterior. Coracobrachialis is lateral and the axillary vein cervical artery. It supplies adjacent muscles and the thoracic wall. It is
is medial. Branches of the brachial plexus are arranged as follows: lat accompanied distally by the nerve to latissimus dorsi. Approximately
erally, the lateral root and then trunk of the median nerve and, for a 4 cm from its origin, the subscapular artery divides into the circumflex
short distance, the musculocutaneous nerve; medially, the medial cuta scapular and thoracodorsal arteries.
neous nerve of the forearm between the axillary artery and vein anteri
orly, and the ulnar nerve between these vessels posteriorly; anteriorly, Circumflex scapular artery The circumflex scapular artery, the
the medial root of the median nerve; and posteriorly, the radial and larger of the two terminal branches of the subscapular artery, curves


axillary nerves, the latter only to the distal border of subscapularis. The backwards around the lateral border of the scapula, traversing a trian
dispositions of the branches of the brachial plexus around the axillary gular space between subscapularis above, teres major below and the
artery have, therefore, altered: there has been a rotation such that the long head of the triceps laterally (see Fig. 48.33). It enters the infrasp
nerves derived from the lateral cord are now more anterior, those from inous fossa under teres minor and then divides. One branch (infras
the medial cord more posterior, and those of the posterior cord come capular) enters the subscapular fossa deep to subscapularis, and
to lie more laterally. anastomoses with the suprascapular and dorsal scapular arteries (or
deep branch of the transverse cervical artery). The other branch contin
Branches ues along the lateral border of the scapula between teres major and
The branches of the axillary artery are one from the first part (superior minor, then, dorsal to the inferior angle, anastomoses with the dorsal
thoracic), two from the second part (thoracoacromial, lateral thoracic) scapular artery. Small branches supply the posterior part of deltoid and
and three from the third part (subscapular, anterior and posterior cir the long head of triceps, and anastomose with an ascending branch of
cumflex humeral) (see Fig. 48.47). the profunda brachii artery.
Superior thoracic artery Thoracodorsal artery The other terminal branch of the subscapular
The superior thoracic artery is a small vessel that arises from the first artery, the thoracodorsal artery, follows the lateral margin of the scapula,
part of the axillary artery near the lower border of subclavius; it some posterior to the lateral thoracic artery, between latissimus dorsi and
times arises from the thoracoacromial artery (see Fig. 48.47). It runs serratus anterior. Before entering the deep surface of latissimus dorsi, it


anteromedially above the medial border of pectoralis minor, then supplies teres major and the intercostals, and sends one or two branches
passes between it and pectoralis major to gain the thoracic wall. It sup to serratus anterior. It enters latissimus dorsi muscle with the thoraco
plies these muscles and the thoracic wall, and anastomoses with the dorsal nerve; this constitutes the principal neurovascular pedicle to the
internal thoracic and upper intercostal arteries. muscle. It provides numerous musculocutaneous perforators that
supply the skin over the superior part of latissimus dorsi. The intramus
Thoraco-acromial (acromiothoracic) artery cular portion of the artery anastomoses with intercostal arteries and
The thoracoacromial artery is a short branch that arises from the lumbar perforating arteries.
second part of the axillary artery (see Figs 48.27, 48.47). It is, at first,
overlapped by pectoralis minor, skirting its medial border; it next anterior circumflex humeral artery
pierces the clavipectoral fascia and divides into pectoral, acromial, cla The anterior circumflex humeral artery arises from the lateral side of
vicular and deltoid branches, which supply pectoralis major and minor, the axillary artery at the distal border of subscapularis (see Fig. 48.31).
an area of skin over the clavipectoral fascia, and the anterior portion of It runs horizontally behind coracobrachialis and the short head of
deltoid. biceps, anterior to the surgical neck of the humerus. Reaching the inter
tubercular sulcus, it sends an ascending branch to supply the humeral
Pectoral branch The pectoral branch is the largest branch. It head and shoulder joint (Brooks et al 1993). It continues laterally
descends between the pectoral muscles, gives a branch to pectoralis under the long head of biceps and deltoid, and anastomoses with the
minor, and then continues on the deep surface of pectoralis major. It posterior circumflex humeral artery.
enters the muscle and anastomoses with the intercostal branches of the
Posterior circumflex humeral artery


internal thoracic and lateral thoracic arteries. It gives off perforating
branches to the breast, and musculocutaneous perforators to the skin The posterior circumflex humeral artery is larger than the anterior (see
over pectoralis major. Fig. 48.31). It branches from the third part of the axillary artery at the
distal border of subscapularis and runs backwards with the axillary
Acromial branch The acromial branch crosses the coracoid process nerve through a quadrangular space (see Fig. 48.22B), which is bounded
under deltoid, which it supplies, then pierces the muscle and ends on by subscapul aris, the capsule of the shoulder joint and teres minor
the acromion. It anastomoses with branches of the suprascapular artery, above, teres major below, the long head of triceps medially, and the
the deltoid branch of the thoracoacromial artery and the posterior surgical neck of the humerus laterally. It curves round the humeral neck
circumflex humeral arteries. and supplies the shoulder joint, deltoid, teres major and minor, and
long and lateral heads of triceps (Gerber et al 1990). It gives off a
Clavicular branch The clavicular branch ascends medially between descending branch that anastomoses with the deltoid branch of the
the clavicular part of pectoralis major and the clavipectoral fascia. It profunda brachii artery and with the anterior circumflex humeral and
supplies the sternoclavicular joint and subclavius. acromial branches of the suprascapular and thoracoacromial arteries.
Deltoid branch The deltoid branch often arises with the acromial Variants
branch. It crosses pectoralis minor to accompany the cephalic vein The branches of the axillary artery exhibit considerable variation. An
between pectoralis major and deltoid, and supplies both muscles. alar thoracic artery, often from the second part, may supply fat and
lymph nodes in the axilla. The lateral thoracic artery may be absent, in
lateral thoracic artery which case it is replaced by lateral perforating branches of the intercos


The lateral thoracic artery arises from the second part of the axillary tal arteries; alternatively, it may become, or give off, a direct cutaneous
artery. Following the lateral border of pectoralis minor, it passes to the vessel (named the superficial thoracic artery by some sources) that sup
deep surface of pectoralis major as far distally as the fifth intercostal plies the skin over the lateral border of pectoralis major. In up to one
space (see Fig. 48.45). It supplies serratus anterior and the pectoral third of cases, the subscapular artery can arise from a common trunk
muscles, the axillary lymph nodes and subscapularis. It anastomoses with the posterior circumflex humeral artery. Occasionally, the sub
with the internal thoracic, subscapular and intercostal arteries, and with scapular, circumflex humeral and profunda brachii arteries arise in
the pectoral branch of the thoracoacromial artery. In females, it is large common; in this case, branches of the brachial plexus surround this
and has lateral mammary branches, which curve round the lateral common vessel instead of the axillary artery. The posterior circumflex


Shoulder girdle and arm
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Two significant cutaneous branches arise from the circumflex scapu
lar artery as it emerges through the upper triangular space. The superior,
or horizontal, branch is a direct cutaneous artery that passes medially
at the level of the deep fascia parallel with the spine of the scapula; it
supplies a band of skin overlying the spine of the scapula. The lower
branch (parascapular branch) is also a direct cutaneous vessel that
passes in an inferomedial direction, again at the level of the deep fascia,
and supplies an area of skin overlying the lateral border of the scapula.
Both of these cutaneous vessels provide the anatomical basis of skin
flaps that can be surgically raised in this region (scapular flap based on
the horizontal branch and parascapular flap based on the lower, paras
capular branch) to reconstruct areas of missing tissue elsewhere in the
body.


Vascular supply and lymphatic drainage
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humeral artery may arise from the profunda brachii artery and pass back of coracobrachialis and brachialis. Proximally, the median nerve and
below teres major, instead of passing through the quadrangular space. coracobrachialis lie laterally and the medial cutaneous nerve of the
Sometimes, the axillary artery divides into radial and ulnar arteries forearm and ulnar nerve lie medially. Distally, biceps brachii overlaps
(anomalous ‘high division’), and is, occasionally, the source of the the artery laterally and the median nerve and basilic vein lie medially.
anterior interosseous artery. The artery is accompanied by two venae comitantes, connected by
transverse and oblique branches. At the elbow, the brachial artery sinks
Potential vascular anastomoses around the
deeply into the triangular intermuscular cubital fossa and its further
shoulder girdle: clinical relevance course is described on page 856.
Available with the Gray’s Anatomy e-book Variants The brachial artery, with the median nerve, may diverge from
the medial border of biceps brachii and descend towards the medial
Angiomyosomes humeral epicondyle, usually behind a supracondylar process from
which a fibrous arch crosses the artery, and which then runs behind or
through pronator teres to the elbow. Occasionally, the artery divides
Available with the Gray’s Anatomy e-book
proximally into two trunks that reunite. Frequently, it divides more
proximally than usual into radial, ulnar and common interosseous
Brachial artery
arteries. Most often, the radial branches arise proximally, leaving a
common trunk for the ulnar and common interosseous arteries. Some
The brachial artery, a continuation of the axillary, begins at the distal times, the ulnar artery arises proximally and the radial and common
(inferior) border of the tendon of teres major and ends about a centi interosseous arteries form the other division, or the common interos
metre distal to the elbow joint (at the level of the neck of the radius) seous may also arise proximally. Slender vasa aberrantia may connect