The central nervous system the spinal cord,Xiaoming Zhang Department of Human Anatomy School of Medicine Zhejiang University,The Spinal Cord 1. External features: Location: foramen magnum - lower border of first lumbar vertebra Shape: A long cylindrical structure Enlargements: cervical enlargement lumbar enlargement Conus medullaris Filum terminale,main longitudinal fissure and sulci on surface: Cauda equina posterior lateral posterior median sulcus anterior lateral anterior median,sulcus,fissure,sulcus,Filum terminale,Spinal segment: Its a part of spinal cord, which is connected with the rootlets of a pair of spinal nerve. 31 segments 8 cervical segments 12 thoracic segments 5 lumbar segments 5 sacral segments 1 coccygeal segments,Corresponding relationship between spinal segments and vertebrae spinal segments correspond to vertebrae C1-C4 C1-C4 C5 T8, T l T4 C4 - C7, C7 T3 T5 T8 T3 T6 T9-T12 T6-T9 L1-L5 T10-T12 S lS5,Co1 LI,2. Internal structure The central canal Gray matter: parts: Lateral horn (only extends from Tl to L3 segments.) gray commissure (anterior and posterior ),Lateral horn,posterior horn,gray commissure,Intermediate zone,anterior horn,central canal,Gray matter,Main nuclei: anterior horn: medial group lateral group intermediate zone: intermediolateral nucleus intermediomedial nucleus posterior horn: the nucleus posteromarginalis the substantial gelatinosa the nucleus proprius: the dorsal nucleus (thoracic nucleus),medial group,lateral group,intermediolateral nucleus,Intermediomedial nucleus:,the nucleus posteromarginalis,the substantia gelatinosa,the nucleus proprius,the dorsal nucleus (thoracic nucleus),The nuclei and the laminas,the nucleus posteromarginalis,the substantia gelatinosa,the nucleus proprius,the dorsal nucleus (thoracic nucleus),intermediolateral nucleus,Intermediomedial nucleus:,medial group,lateral group,White matter: parts:,posterior funiculus,lateral funiculus,anterior funiculus,anterior white commissure,posterior lateral sulcus,posterior median sulcus,anterior lateral sulcus,anterior median fissure,Main tracts (or fasciculi): long ascending tracts: fasciculus gracilis: come from sacral, lumbar and lower six thoracic nerves, terminate upon nucleus gracilis fascicules cuneatus: come from cervical and upper six thoracic nerves, terminate upon nucleus cuneatus. *conduct the fine tactile (e.g.two-point discrimination) and kinesthetic sense (e.g.position and movement and vibration)of the ipsilateral trunk and limbs.,fascicules gracilis,fascicules cuneatus,lateral and anterior spinothalamic tracts: *in corresponding funiculus *arises from opposite nucleus proprius *terminate on thalamus *conduct pain, thermal and rough tactile sense of opposite trunk and limbs,thalamus,anterior spinothalamic tracts,anterior spinothalamic tracts,nucleus proprius,main long descending tracts lateral corticospinal tract: *arises from opposite cerebral cortex *descends through lateral funiculus of spinal cord *terminate on ipsilateral anterior horn (lateral group) *controls the contraction of skeletal muscles of ipsilateral limbs anterior corticospinal tract: *controls the movement of bilateral muscles of trunk,lateral corticospinal tract,anterior corticospinal tract,Other descending tracts: they are related to regulate muscle tonus,tectospinal tract,Rubrospinal tract,vestibulospinal tract,Reticulospinal tract,lateral corticospinal tract,anterior corticospinal tract,anterior spinothalamic tracts,anterior spinothalamic tracts,fascicules cuneatus,Fascicules gracilis,Functions: To convey afferent impulses, which come from somatic and visceral receptors to the brain, and conduct efferent impulses from brain to effectors. Related to reflexes,good bye！,