-1- 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 Nervous system

-2- shape ： two enlargement ： cervical enlargement ⑸ lumbosacral enlargement ⑹ Location And External Features 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. Spinal cord anterior median fissure ⑴ posterior median sulcus ⑵ anterolateral sulci ⑶ posterolateral sulci ⑷ stripes of sulcus ： ⑴⑵ ⑶ ⑷ ⑸ ⑹

-3- Conus medullaris ⑴ Filum terminale ⑵ Cauda equina ⑶ Spinal nerve （ 31 pairs ） Anterior root ⑷ （ motor ） Posterior root ⑸ （ sense ） ⑴ ⑵ ⑶ ⑷ ⑸ ⑵

-4- C 1 - C 4 C 5 - T 4 T III - T VI T VI - T IX T X - T XII LILI T 5 - T 8 T 9 - T 12 L 1 - L 5 S 1 - Co 1 C IV - T III C I - C IV The relationship with vertebrae vertebrae spinal cord 31 segments ： C 8 、 T 12 、 L 5 、 S 5 、 Co 1 The spinal segment refers to a region of the spinal cord from which a pair of spinal nerves arises.

-5- 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 Internal Structure

-6- Lamina Ⅲ Lamina Ⅳ Lamina Ⅰ — marginal layer （ areas spongiosa ） Lamina Ⅱ — substantia gelatinosa Laminas of the gray matter Rexed layers Lamina Ⅴ Lamina Ⅵ receive the afferent fibers of proprioceptive sense and regulate movement nucleus proprius Lamina Ⅶ 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 S 2 － 4 ， visceral motor 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 cell ⑶ ： receive α- axon collateral of motor 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- 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 The relationship between the laminas and the nuclei of the spinal cord

-9- Tracts of the Spinal Cord Ascending Tracts fasciculus gracilis ⑴ below T5 fasciculus cuneatus ⑵ above T4 —conduct conscious proprioceptive sense ⑴ ⑵

-10- 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 direct cerebellar tract 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 somatic reflexes —reflexes that result in the contraction of skeletal muscles superficial (skin and mucous membrane) reflexes and deep (myotatic) reflexes etc visceral reflexes —the contraction of smooth or cardiac muscle or secretion by glands such as carotid sinus, bladder and rectal reflex,etc. 1 ） receptor ， 2 ） afferent neuron ， 3 ） interneurons neuron ， 4 ） efferent ， 5 ） effector The simple reflex arc includes

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

-14- Flexor Reflexes skin posterior roots posterior horn interneurons neuron α- motor neurons Muscle contraction anterior roots

-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