[Plate 158, Relation of Spinal Nerve Roots to Vertebrae]page 89
page 9031 pairs of spinal nerves
8 cervical, 12 thoracic, 5 lumbar, 5 sacral, 1 coccygeal
C1-C7 exit superior to corresponding vertebrae
C8 exits inferior to the C7 vertebra
T1-Co exit inferior to corresponding vertebrae
Cauda equina: spinal nerve roots inferior to the conus medullaris, travelling obliquely to exit vertebral canal
Ventral roots
Carry efferent (motor) fibers with their cell bodies in the ventral horn of the cord
May contain presynaptic autonomic fibers
Dorsal roots
Carry afferent (general and visceral sensory) fibers with their cell bodies in the dorsal root ganglion (DRG)
May be absent in C1 and Co
Ventral and dorsal roots: combine to form a (mixed) spinal nerve which exits through the intervertebral foramen and divides almost
immediately into (mixed) ventral and dorsal rami
Ventral rami
Anterior and lateral branches
Form plexuses and supply the limbs and trunk
Dorsal rami
Medial and lateral branches
Supply the skin and true muscles of the back