Download Spinal Nerves - Buckeye Valley

Spinal Nerves
Spinal nerves
• 31 pairs arise from
spinal cord
• Five groups correspond
to regions of spinal cord
and vertebrae
– Cervical 8 pr.
– Thoracic 12 pr.
– Lumbar 5 pr.
– Sacral 5 pr.
– Coccygeal 1 pr.
Structure of a Nerve
• Bundle of axons
• Layers of
connective tissue
– Epineurium
– Perineurium
– Endoneurium
Structure of a spinal nerve
• Tree analogy
• Dorsal root & ventral
root fuse lateral to
dorsal root ganglion
• Whole nerve "trunk"
lies in intervertebral
foramen
Structure of a spinal nerve
• Branches
• Dorsal ramus
• Ventral ramus
• Communicating rami
to sympathetic chain
ganglion (ANS)
Spinal Nerve Plexuses
Spinal Nerve Plexuses
• Ventral rami of spinal nerves fuse and form
networks with ventral rami of other spinal
nerves.
– Crossing of fibers
• A peripheral nerve may contain axons from several
spinal segments.
• T2 – T12 do not form plexuses
Spinal Nerve Plexuses
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Cervical plexus
Brachial plexus
Lumbar plexus
Sacral plexus
• C1 – C4 (+ C5)
– cutaneous nerves, mostly sensory from skin of neck & back
of head
– Phrenic nerve to diaphragm
• Motor stimulation for breathing!
Cervical plexus
Brachial plexus
• C5 – T1
• Complex fusion,
splitting, fusion, &
division into nerves
• Axillary Nerve
– to deltoid
• Musculocutaneous
nerve
– to biceps brachii,
brachialis
• Radial nerve
– to triceps brachii, extensors of wrist, hand, fingers
• Wrist drop
• Median nerve
– to flexors of wrist, hand, fingers
– can be compressed
• Carpal Tunnel Syndrome
• Ulnar nerve
– (“funny bone”)
– to flexors in hand
• “Claw hand”
Brachial plexus
• L1 – L4 (+ L5)
• Ilioinguinal nerve
– mostly sensory from skin of thigh & genitals
• Genitofemoral nerve
– mostly sensory from scrotum, labia majora, ant. Thigh
• Femoral Nerve
– to quadriceps, sartorius
Lumbar plexus
• L4 – S4
• Superior & inferior gluteal nerves
– To gluteus muscles
• Sciatic nerve
– To hamstrings & other posterior thigh & leg muscles
• Pudendal nerve
– Sensory from penis, clitoris, labia minora, anus
Sacral plexus