Lumbar, Sacral, and Coccygeal Plexuses
The lumbar plexus is produced by the union of the ventral rami of the first three lumbar nerves and the greater part of the fourth, with a contribution from the…
Distribution of Motor and Sensory Fibers
Cranial nerve motor nuclei are located medially, whereas the sensory nuclei are found generally more lateral. Three types of motor nuclei are present innervating voluntary striated muscles (somatic), muscles of…
Thoracic Spinal Nerve Root Disorders
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Diabetic Lumbosacral Radiculoplexus Neuropathy
Diabetic lumbosacral radiculoplexus neuropathy is a painful condition that causes severe weakness and muscle wasting of the lower extremities. A number of clinical terms have been applied to this syndrome,…
Thoracic Nerves
The dorsal rami of the thoracic nerves run backward near the zygapophyseal joints, which they supply, and divide into medial and lateral branches. Both sets of branches pass through the…
Spinal Nerves
The upper cervical spinal nerves lie horizontally, but all the others assume an increasingly oblique and downward direction as they proceed to their foramina of exit. In the adult, the…
Dermal Segmentation
The spinal cord is segmental in character, and the spinal nerves are distributed to structures developed from the associated segments, or metameres (see Plate 2-1). In the trunk, the correspondence…
Lumbosacral Spinal Stenosis
Spondylolisthesis, in which one vertebral body translates anteriorly or posteriorly with respect to an adjacent vertebral body, can also occur, exacerbating the spinal canal narrowing. The L4-5 level is most…
L4-5 Disk Extrusion
In patients in whom further treatment is necessary because of pain or neurologic deficit, surgery must be considered and must be preceded by imaging of the lumbosacral spine to rule…
Lumbar Disk Herniation: Clinical Manifestations
The S1 root syndrome includes sciatic pain (“sciatica”) from the buttock to the posterior thigh, to the posterior or lateral calf, and into the foot. When due to disk herniation,…
