Chapter 17 Central Nervous System

1. Nervous system Chapter 17 Central Nervous System The spinal cord Location And External Features Internal Structure the manifestation of spinal reflex and post-trauma Functions Of The Spinal Cord Brain

2. Spinal cord ⑴ ⑵ Location And External Features ⑶ ⑸ position：lie in vertebral canal The superior extremity is linked with medulla oblongata at the level of great occipital foramen. The inferior extremity is at the level of the inferior border of first body of lumber vertebra in adult. ⑷ shape： two enlargement： cervical enlargement⑸ lumbosacral enlargement⑹ stripes of sulcus： ⑹ anterior median fissure⑴ posterior median sulcus⑵ anterolateral sulci⑶ posterolateral sulci⑷

3. Conus medullaris ⑴ Filum terminale ⑵ Cauda equina⑶ Spinal nerve（31 pairs） Anterior root⑷（motor） Posterior root⑸（sense） ⑴ ⑵ ⑶ ⑵ ⑸ ⑷

4. C1 - C4 CI - CIV - 0 C5 - T4 CIV - TIII - 1 T5 - T8 TIII - TVI - 2 T9 - T12 TVI - TIX - 3 L1 - L5 TX - TXII S1 - Co1 LI The relationship with vertebrae The spinal segment refers to a region of the spinal cord from which a pair of spinal nerves arises. 31 segments：C8、T12、L5、S5、Co1 spinal cord vertebrae

5. Internal Structure central canal anterior (ventral) horn or anterior column posterior (dorsal) horn or posterior column lateral horn or lateral column intermediate zone central gray posterior gray commissure anterior gray commissure white matter anterior funiculus lateral funiculus posterior funiculus anterior white commissure reticular formation terminal ventricle

6. intermediomedial nucleus——is related to visceral sensory intermediolateral nucleus——is related to visceral motor thoracic nucleus（Clark’s column）—unconscious proprioceptive sense sacral parasympathetic nucleus—is correspond to layer Ⅶ at the segment S2－4，visceral motor Lamina Ⅶ Laminas of the gray matter Rexed layers Lamina Ⅰ —marginal layer（areas spongiosa） Lamina Ⅱ —substantia gelatinosa Lamina Ⅲ Lamina Ⅳ nucleus proprius Lamina Ⅴ Lamina Ⅵ receive the afferent fibers of proprioceptive sense and regulate movement Lamina Ⅷ —interneuron, effect the γ and α motor neuron

7. Layer Ⅸ— motor neuron of anterior horn medial nucleus of anterior horn：trunk muscle lateral nucleus of anterior horn：limb muscle α-motor nerve ⑴ ：dominate the extrafusal muscle fiber of straddling joint→joint movement γ-motor nerve ⑵：dominate intrafusal fiber→regulate muscular tension Renshaw cell⑶：receive α- axon collateral ofmotor nerve and send out branches and form reverse feedback loop with it. layer Ⅹ— central gray：receive some posterior root fiber Ⅹ ⑴ ⑵ ⑶

8. The relationship between the laminas and the nuclei of the spinal cord Laminas Nuclei I posteriomarginal nucleus II substantia gelatinosa III, IV nucleus proprius V reticular nucleus VI base of posterior column VII thoracic nucleus, intermediomedial nucleus, intermediolateral nucleus, sacral parasympathetic nucleus VIII, IX medial motor neuron column, lateral motor neuron column X central gray matter

9. Tracts of the Spinal Cord ⑴ ⑵ Ascending Tracts fasciculus gracilis⑴ below T5 fasciculus cuneatus⑵above T4 —conduct conscious proprioceptive sense

10. direct cerebellar tract posterior spinocerebellar tract anterior spinocerebellar tract —conduct unconscious proprioceptive sense spinothalamic tract lateral spinothalamic tract ⑴ —conduct crude sense of touch and pressure sensation anterior spinothalamic tract ⑵ —conduct sense of pain and warm ⑴ ⑵

11. Descending Tracts corticospinal tract：body movement lateral corticospinal tract ⑴ anterior corticospinal tract ⑵ anterolateral corticospinal tract (of Barnes) rubrospinal tract： flexor excited vestibulospinal tract ： extensor excited reticulospinal tract： motor control of proximal muscle of trunk and limbs tectospinal tract： excite the cervical muscle of opposite side, inhibit cervical muscle of homonymy medial longitudinal fasciculus： regulating the ocular movement and head position

12. Functions of the Spinal Cord Conduction pathway； reflex centre。 spinal reflex The simple reflex arc includes 1）receptor，2）afferent neuron，3）interneuronsneuron， 4）efferent ，5）effector somatic reflexes—reflexes that result in the contraction of skeletal muscles superficial (skin and mucous membrane) reflexes and deep (myotatic) reflexesetc visceral reflexes—the contraction of smooth or cardiac muscle or secretion by glands such as carotid sinus, bladder and rectal reflex,etc.

13. Stretch Reflexes stretch reflex（tendon reflexes）： muscle、tendon posterior roots α-motor neurons anterior roots Muscle contraction

14. Flexor Reflexes skin posterior roots posterior horn interneuronsneuron α-motor neurons anterior roots Muscle contraction

15. Clinical Consideration The spinal cord transection spinal shock Hemisection of the spinal cord Brown-Se´quard syndrome Lesion of anterior horn of the spinal cord flaccid paralysis Lesion around the central gray matter peripheral dissociation