anterior white commissure anterior white commissure the anterior white commissure (ventral white commissure) is a bundle of nerve fibers which cross the midline of the spinal cord just anterior (in front of) to the gray commissure (rexed lamina x). a delta fibers (aδ fibers) and c fibers carrying pain sensation in the spinothalamic tract contribute to this commissure, as do fibers of the anterior corticospinal tract, which carry motor signals from the primary motor cortex. this article is about the anterior commissure of the spinal cord. for the anterior commissure of the brain, see anterior commissure. anterior white commissure of the spinal cordfig. 664– transverse section of the medullaspinalis in the mid-thoracic region.the white commissure is highlighted in green.detailsidentifierslatincommissura alba anterior medullae spinalis, alba anterior medullae spinalista98a14.1.02.305ta26125fma77035anatomical terms of neuroanatomy two of the five sensory modalities, pain and temperature, cross sides at the anterior white commissure, reaching the contralateral side about two vertebral levels rostral to their origin. the spinothalamic tract thus decussates very soon after entering the spinal cord, ascending in the spinal cord, contralateral to the side from where it provides (pain and temperature) sensory information. therefore, a lesion that is caudal to the sensory decussation where the remaining three-fifths modalities decussate (at the superior medulla) will result in contralateral (opposite sided) pain and temperature loss (as this has already crossed over at the anterior white commissure), whereas loss of crude touch, pressure, and proprioception will be ipsilateral (same sided) as these have not yet crossed over. the spinal cordgeneral features cervical enlargement lumbar enlargement conus medullaris filum terminale cauda equina meninges central canal terminal ventricle grey columnsposterior grey column marginal nucleus substantia gelatinosa of rolando nucleus proprius rexed lamina v rexed lamina vi lateral grey column intermediolateral nucleus posterior thoracic nucleus anterior grey column interneuron alpha motor neuron onuf's nucleus gamma motor neuron other rexed laminae central gelatinous substance gray commissure white mattersensoryposterior posterior column-medial lemniscus pathway gracile cuneate lateral spinocerebellar dorsal ventral spinothalamic lateral anterior posterolateral spinotectal anterior spinoreticular tract spino-olivary tract motorlateral corticospinal lateral extrapyramidal rubrospinal raphespinal reticulospinal hypothalamospinal anterior corticospinal anterior extrapyramidal vestibulospinal reticulospinal tectospinal raphespinal olivospinal both anterior white commissure external features ventral anterior median fissure anterolateral sulcus dorsal posterior median sulcus posterolateral sulcus brain and spinal cord: neural tracts and fasciculisensorydcml1°: pacinian corpuscle/meissner's corpuscle → posterior column (gracile fasciculus/cuneate fasciculus) → gracile nucleus/cuneate nucleus 2°: → sensory decussation/arcuate fibers (posterior external arcuate fibers, internal arcuate fibers) → medial lemniscus/trigeminal lemniscus → thalamus (vpl, vpm) 3°: → posterior limb of internal capsule → postcentral gyrus anterolateral/painfast/lateral 1° (free nerve ending → a delta fiber) → 2° (anterior white commissure → lateral and anterior spinothalamic tract → spinal lemniscus → vpl of thalamus) → 3° (postcentral gyrus) → 4° (posterior parietal cortex) 2° (spinomesencephalic tract → superior colliculus of midbrain tectum) slow/medial 1° (group c nerve fiber → spinoreticular tract → reticular formation) → 2° (md of thalamus) → 3° (cingulate cortex) motorpyramidal flexion: primary motor cortex → posterior limb of internal capsule → decussation of pyramids → corticospinal tract (lateral, anterior) → neuromuscular junction extrapyramidalflexion: primary motor cortex → genu of internal capsule → corticobulbar tract → facial motor nucleus → facial muscles flexion: red nucleus → rubrospinal tract extension: vestibulocerebellum → vestibular nuclei → vestibulospinal tract extension: vestibulocerebellum → reticular formation → reticulospinal tract midbrain tectum → tectospinal tract → muscles of neck basal gangliadirect:1° (motor cortex → striatum) → 2° (gpi) → 3° (lenticular fasciculus/ansa lenticularis → thalamic fasciculus → vl of thalamus) → 4° (thalamocortical radiations → supplementary motor area) → 5° (motor cortex)indirect:1° (motor cortex → striatum) → 2° (gpe) → 3° (subthalamic fasciculus → subthalamic nucleus) → 4° (subthalamic fasciculus → gpi) → 5° (lenticular fasciculus/ansa lenticularis → thalamic fasciculus → vl of thalamus) → 6° (thalamocortical radiations → supplementary motor area) → 7° (motor cortex)nigrostriatal pathway: pars compacta → striatum cerebellarafferent vestibular nuclei → vestibulocerebellar tract → icp → cerebellum → granule cell pontine nuclei → pontocerebellar fibers → mcp → deep cerebellar nuclei → granule cell inferior olivary nucleus → olivocerebellar tract → icp → hemisphere → purkinje cell → deep cerebellar nuclei efferent dentate nucleus in lateral hemisphere/pontocerebellum → scp → dentatothalamic tract → thalamus (vl) → motor cortex interposed nucleus in intermediate hemisphere/spinocerebellum → scp → reticular formation, or → cerebellothalamic tract → red nucleus → thalamus (vl) → motor cortex fastigial nucleus in flocculonodular lobe/vestibulocerebellum → vestibulocerebellar tract → vestibular nuclei bidirectional:spinocerebellarunconscious proprioception lower limb → 1° (muscle spindles → drg) → 2° (posterior thoracic nucleus → dorsal/posterior spinocerebellar tract → icp → cerebellar vermis) upper limb → 1° (muscle spindles → drg) → 2° (accessory cuneate nucleus → cuneocerebellar tract → icp → anterior lobe of cerebellum) reflex arc lower limb → 1° (golgi tendon organ) → 2° (ventral/anterior spinocerebellar tract→ scp → cerebellar vermis) upper limb → 1° (golgi tendon organ) → 2° (rostral spinocerebellar tract → icp → cerebellum) authority control terminologia anatomica this article is issued from wikipedia. the text is licensed under creative commons - attribution - sharealike. additional terms may apply for the media files.