NETTER - Neuroscience Flash Cards

Spinal Cord: Its Meninges and
Spinal Roots
1. Rami communicantes
2. Dura mater
3. Dorsal root
4. Dorsal root (spinal) ganglion
5. Arachnoid membrane
6. Filaments of a dorsal root
7. Denticulate ligament
8. Ventral root
9. Filaments of a ventral root
10. Anterior median fissure
11. Anterior funiculus
Comment: Even though the dorsal and ventral roots emerge
through the intervertebral foramina as 31 pairs of discrete nerve
roots, a continuous line of small nerve rootlets coalesce to form
these discrete nerve roots. The most vulnerable sites for herniated
discs and subsequent nerve root compression are at L4-L5 and
L5-S1, and less commonly the C6-C7, C5-C6, and C4-C5 cervical
discs. Impingement of a herniated disc on a nerve root results
in radiating pain in the specific distribution of that nerve root (a
dermatomal pattern). However, the loss of sensation occurring from
a nerve root lesion does not occur in a dermatomal pattern because
of overlap of sensory projections to the spinal cord. At least three
successive nerve roots would have to be damaged to produce
complete anesthesia in a dermatomal pattern. This is not the case for
the three divisions of the trigeminal nerve, which share no overlap.
Overview of the Nervous System See book 5.4