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 Filum terminale sulcus fissure

It's a part of spinal cord, which is connected Spinal segment: It's 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 l~S5,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 ) posterior horn central canal Intermediate zone Lateral horn anterior horn Gray matter gray commissure

Main nuclei: anterior horn: medial group intermediate zone: lateral group intermediate zone: intermediolateral nucleus intermediomedial nucleus posterior horn: the nucleus posteromarginalis the substantial gelatinosa the nucleus proprius: the dorsal nucleus (thoracic nucleus) the nucleus posteromarginalis the substantia gelatinosa the nucleus proprius the dorsal nucleus (thoracic nucleus) Intermediomedial nucleus: intermediolateral nucleus lateral group medial group

The nuclei and the laminas the nucleus posteromarginalis the substantia gelatinosa the nucleus proprius the dorsal nucleus (thoracic nucleus) intermediolateral nucleus Intermediomedial nucleus: lateral group medial group

White matter: parts: posterior funiculus lateral funiculus posterior median sulcus posterior lateral sulcus lateral funiculus anterior lateral sulcus anterior white commissure anterior funiculus 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 cuneatus fascicules gracilis

lateral and anterior spinothalamic tracts: *in corresponding funiculus thalamus 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 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 Fascicules gracilis fascicules cuneatus lateral corticospinal tract Rubrospinal tract anterior spinothalamic tracts Reticulospinal tract anterior spinothalamic tracts vestibulospinal tract tectospinal tract anterior corticospinal tract

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

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