Spinal Nerves Spinal nerves 31 pairs arise from

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Spinal Nerves

Spinal Nerves

Spinal nerves • 31 pairs arise from spinal cord • Five groups correspond to

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 –

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

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 •

Structure of a spinal nerve • Branches • Dorsal ramus • Ventral ramus • Communicating rami to sympathetic chain ganglion (ANS)

Spinal Nerve Plexuses

Spinal Nerve Plexuses

Spinal Nerve Plexuses • Ventral rami of spinal nerves fuse and form networks with

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. • T 2 – T 12 do not form plexuses

Spinal Nerve Plexuses • • Cervical plexus Brachial plexus Lumbar plexus Sacral plexus

Spinal Nerve Plexuses • • Cervical plexus Brachial plexus Lumbar plexus Sacral plexus

 • C 1 – C 4 (+ C 5) – cutaneous nerves, mostly

• C 1 – C 4 (+ C 5) – cutaneous nerves, mostly sensory from skin of neck & back of head – Phrenic nerve to diaphragm • Motor stimulation for breathing! Cervical plexus

Brachial plexus • C 5 – T 1 • Complex fusion, splitting, fusion, &

Brachial plexus • C 5 – T 1 • 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 •

• 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

 • L 1 – L 4 (+ L 5) • Ilioinguinal nerve –

• L 1 – L 4 (+ L 5) • 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

 • L 4 – S 4 • Superior & inferior gluteal nerves –

• L 4 – S 4 • 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