SPINAL CORD AND NERVES

1/14/82, 25 Jan 1996, 20 Jan 98, 18 Jan 00, 29 Jan 03, 26 Jan 05, 28Jan08

S&M p 321, Martini, 426-452, Martini’s 4^th: 417-4435, Martini’s 7^th: 429-460

The Spinal Cord: (p 424)

 as embryo grows, cord grows less.

End of cord branches extensively at L1: meninges form filum terminale at conus medularis. (p 424)

             lumbar puncture between L3 and L4 where cauda equina is found (test for meningitis, blood)

Two enlargements: cervical and lumbar innervate upper and lower limbs

Anterior median fissure, posterior median sulcus on cord

             dura mater extends laterally, blends with epineurium (connective tissue covering nerve )

             arachnoid and pia mater as in brain.

ANATOMY OF SPINAL CORD CROSS SECTION: (P 428)

dorsal ramus of spinal cord (serves skin and muscles of back)

             anterior gray horn                                 somatic motor cell bodies

             posterior gray horn                                axons of sensory and internuncial cell bodies

             lateral horn                                             cell bodies of visceral (autonomic) motor neurons

             gray commissure

             posterior funiculus (white)                       sensory cord

             lateral funiculus (white)                           sensory and motor cord

             anterior funiculus (white)                        sensory and motor cord

             central canal

             posterior median sulcus

             anterior median fissure

             dura mater                                                enfolds cord, roots, ganglia, separate for sympathetic ganglia

             ventral root                                               carries only motor fibers

             dorsal root of spinal nerve                       carries axons from dorsal root ganglion

             dorsal root ganglion                                 houses primary sensory neurons

             ventral ramus of spinal nerve 

             spinal nerve                                              forms where dorsal and ventral roots unite

             neural arch

             centrum of vertebra

             denticulate ligament                                 arachnoid's largest connection to cord

SPINAL NERVES:      dorsal rami carry motor and sensory fibers for skin and back muscles:

dermatome(area of skin on surface of body) and muscles (p. 431

Ramifications: referred pain (p.?), shingles

             Upper limbs                     cervical and Tl

             Trunk                               C4 to L5

              Lower limbs                    Ll to S2

              Buttocks                          Sl to S5

referred pain (p 506)

THREE MAJOR PLEXUSES Ventral rami intermix in plexuses: (p 442-445)

1  Cervical: (433)         neck and shoulder, phrenic nerves supplies diaphragm, laryngeal to voice box, etc

2  Brachial: (434)        formed from ventral rami of last four cervical nerves: C5-C8, Three divisions leave: posterior, medial and lateral cords: branch to radial, median and ulnar nerves

3 Lumbosacral: (436)  supplies skin & muscles of buttocks, pelvis, lower abdomen, legs, two plexi:

    3a: Lumbar: from first four lumbar nerves, T12-L4

    3b: sacral plexus: (fr L4, L5 and Sl-S4)      sciatic         main branch

                                                                           pudendal   genitals & muscles, perineum, anal, GU sphincters