Peripheral Nerves Flashcards
Function of the axon
Enable sensory neuron to transmit signals from the sensory receptor to the brain
Schwann cells location and ourpose
Create the myelin sheath around the axon in the PNS.
Make nerve growth factor which enables the nerve to regenerate
Perineurium
Strong elastic tissue that surrounds each fascicle and diffuses input
–blood nerve barrier–
2 pathological responses to nerve damage
Demyelination and axonal loss
How long do sensory end organs remain viable after injury
6-9 months
Sunderland type 3
Involvement of external connective tissue layers
Sunderland type 2
Axonotmesis, axons distal to lesion degenerate
Prognosis is good with axonal regeneration because endoneurial tunes remain intact
Sunderland type 1
Neuropraxia, with damage to myelin sheaths resulting in local conduction block
Example is Saturday night palsy
Resolved in weeks to months
Sunderland type 4
Destruction to the Perineurium
Poor prognosis without surgery because of scar tissue
Surgery might be resection of fibrotic segment of nerve trunk, and repair with graft
Sunderland type 5
Neurotmesis, laceration of nerve trunk.
Complete injury- no recovery without surgery
Soma
Nerve cell body- must be viable for nerve to work or heal
Bergers test
Limericks involvement in carpal tunnel
Hold full fist with wrist neutral for 30-40 sec- pain and parasthesias
Ulnar nerve order of innervation
Fcu Fdp Palmar is brevis Abductor DQ Opponens DQ flexor DQ Lumbricals 3-4 Palmar interossei Dorsal interossei Adductor pollicis
Median nerve order of innervation
Pronator teres Fcr PL Fds (Ain below) Fdp 2-3 Fpl Pronator quadratus (Palm below) Abductor pollicis brevis Opponens pollicis Fpb Lumbricals 1-2
Radial nerve order of innervation
Triceps Anconeus Brachioradialis Ecrl Ecrb (Pin below) Supinator Extensor digitorum Edm Ecu Abd pollicis longus Extensor pollicis brevis Extensor indicis
Protective immobilization time after nerve repair
Approxmately 7-10 days
Hansen’s disease
Used to be leprosy Infectious bacterial disease Ulnar median and radial nerves are affected Sensory loss followed by motor loss Curable with oral chemo
Nerve regeneration per month
About 1 inch
Upper arm regeneration speed
About 8.5mm per day
Final nerve recovery after repair of nerve at wrist
2 years
Sites of compression around Pronator
Ligament of struthers
Deep head of Pronator teres
Lacertus fibrosis
ways to tell its Pronator syndrome not carpal tunnel
No nocturnal pain
Decreased sensation in thenar space
Way to tell its ain involvement not Pronator or carpal tunnel
Weakness in thumb index and middle finger, no parasthesias
Duchenne
Clawing of sf and rf
Egawa
Inability to abduct middle finger at the MP joint
Andre Thomas
Wrist falls into flexion during during middle finger extension
Masse
Flattening of the metacarpal arch
Test for AIN syndrome
Pinch grip test- maintains tip to tip pinch rather than pad to pad
