Quiz 3: Peripheral Nerves

Axons

Carry info away from the cell body.

Dendrites

Carry info toward the cell body.

Fascicles

Bundles of axons.

Endoneurium

Connective tissue around axons.

Perineurium

Connective tissue around fascicles.

Epineurium

Connective tissue around nerves.

Afferent neurons

Carry sensory info toward the CNS.

Efferent neurons

Carry motor info away from the CNS.

Mixed nerve

Contains both sensory and motor fibers.

Sympathetic nervous system

Subsystem of the ANS responsible for fight or flight.

Parasympathetic nervous system

Subsystem of the ANS responsible for rest and digest.

Somatic nerves

Innervate striated skeletal muscles (voluntary).

Nerve healing rate

Repaired nerves heal at 1-3 mm/day after a 3-4 week latency.

Wallerian degeneration

Degeneration of the nerve distal to the injury site.

Double Crush Syndrome

Two compression points along a nerve pathway.

Brachial plexus

Parts include Roots → Trunks → Divisions → Cords → Branches.

Nerves from the brachial plexus

Include Axillary, Musculocutaneous, Median, Radial, Ulnar.

Cubital Tunnel Syndrome

Caused by compression of the ulnar nerve at the elbow; worsened by prolonged elbow flexion or pressure.

Tests for Cubital Tunnel Syndrome

Include Tinel's sign, elbow flexion test, nerve conduction studies.

Guyon's Canal Syndrome

Distal ulnar nerve compression between pisiform and hamate bones.

Radial Nerve Palsy

Compression of the radial nerve leading to wrist drop; often due to trauma.

Anterior Interosseous Syndrome

Proximal motor branch median nerve entrapment → no pinch (OK sign), no sensory loss.

Signs of Pronator Teres Syndrome

Resistance to pronation + elbow flexion = symptoms; sensory changes in dorsal hand.

Carpal Tunnel Syndrome

The most common nerve compression disorder (median nerve).

Phalen's test

Flex wrists and press back of hands together; positive if symptoms are reproduced (CTS).

Spurling's test

Lateral flexion and compression of the neck → positive if symptoms are reproduced (cervical radiculopathy).

Roo's Test

Open/close hands with arms abducted → positive if symptoms occur before 3 mins (TOS).

Conservative treatments for Cubital Tunnel Syndrome

Include activity modification, elbow pads, splints to prevent flexion, nerve glides.

Surgical treatment for Carpal Tunnel Syndrome

Release of the transverse carpal ligament (open or endoscopic).

Semmes-Weinstein testing

Used to evaluate light touch and two-point discrimination.