Peripheral Nerves Flashcards
Shoulder Abduction
Axillary Nerve
C5
Elbow Flexion weakness
Musculocutaneous
Elbow Extension weakness
Radial
Wrist extension weakness
Radial
Wrist flexion weakness
Median
Finger extension weakness
Radial
Finger flexion weakness
Median/(Ulnar)
Axillary Nerve
Deltoid muscle
Shoulder abduction 20-90deg
Regimental patch
C5
Critical movement: Elbow flexors
Controls shoulder
Other:
Half of biceps and brachioradialis jerk
Also shoulder abduction
C6
Elbow joint
Wrist extensors
Also
Elbow flexion with C5
Part of bicps an brachioradialis jerk
C7
Wrist joint
Elbow extension
Triceps Jerk
Also related to wrist extension/flexion
C8
Finger flexion/extension
Key movement is flexion
Part of triceps jerk
T1
Finger abductors
Also involved in finger adduction
Radial Nerve
Extension of everything
Elbow weakness if injury above spiral groove
Brachioradialis, wrist and finger weakness: injury in spiral groove
finger abduction appears weak because hard to spread fingers if not straight!
Sensation:
Posterior aspect of arm
Posterior aspect of hand
Snuffbox
Location of lesion
What does it mean in the upper limb if extension and flexion are weak at the same joint?
Can’t be a peripheral nerve lesion
Sensation of medial aspect of forearm
From brachial plexus
Winging of Scapula
Proximal lesion
Musculocutaneous Nerve
Motor: Elbow Flexion
Sensory: Lateral forearm
Sensation loss involving forearm and hand
Radiculopathy
Median Nerve
Wrist flexion
Finger flexion
Lumbricals
Thumb Abduction
LOAF of hand (thenar eminence): lateral 2 lumbricals, opponens pollicis brevis, abductor pollicis brevis, flexor pollicis brevis
Weakness: wrist and finger flexion
Hand of benediction → unable to flex middle and index finger
Sensation: lateral 3.5 digits
Plus don’t forget palmar branch
Ulnar Nerve
Finger abduction
Finger adduction
For digit 4 + 5: Flexor digitorum profundus and lumbricals
Wasting of intrinsic muscles of hand except thenar
Weak finger abduction and adduction
Ulnar claw hand: hyperextension of MCPJ, flexion at PIPJ and DIPJ
(Higher the lesion, less the deformity - because FDP also weak and doesn’t try to overcome lumbrical weakness)
Froment’s sign: Adductor pollicis weakness, flexor pollicis longus activats instead
Sensory medial aspect 1.5 fingers
Biceps Jerk
C5/C6
Musculocutaneous
Brachioradialis Jerk
C5/C6
Radial
Triceps Jerk
C7/C8
Radial
Upper Trunk Brachial Plexus injury
Loss of C5 and C6
Loss of shoulder movement
Loss of elbow flexion
“waiter’s tip position”
Sensory: lateral aspect of arm and forearm (musculocutaneous)
Lower Trunk Brachial Plexus Injury
C8 - T1
Loss of everything in the hand
Loss of sensation along medial aspect of hand and forearm
Can get a Horner’s syndrome because the sympathetic pathways come from C8-T1 too.
Femoral Nerve
Hip Flexion
Knee Extension (Quads)
Sensation: medial aspect of thigh
Loss of knee jerk
Sciatic Nerve
Knee flexion
Plus distal movement
Flaccid foot drop
Loss of sensation below knee
Loss of ankle jerk and plantar response
Tibial Nerve
Posterior compartment
Plantarflexion
Ankle Inversion
Loss of ankle jerk
Sensory: most of sole of foot
Common Peroneal Nerve
Ankle eversion (Superficial peroneal)
Dorsiflexion - foot drop (Deep peroneal)
Sensory:
Superficial: lateral aspect leg, dorsum of foot
Deep: between 1st and 2nd toe
Inferior Gluteal Nerve
Gluteus Maximus - Hip extension
Obturator Nerve
Hip Adductors
L2
Hip Flexors
L3
Knee Extensors
L4
Ankle Dorsiflexion
Inversion
L5
Long toe extensors
Inversion/eversion
S1
Ankle plantar flexion
Eversion
Myotomes for lower limb
Count down joints
Then around joints
L3 versus Femoral lesion
L3 has addition to hip adduction weakness
Otherwise:
Knee extension weakness
Hip flexion weakness
Loss of Knee Jerk
Sensation similar - down onto knee
Knee Jerk
Femoral Nerve
L3 L4
Ankle Jerk
Tibial Nerve
S1 S2
Foot Drop
L4/L5: loss of inversion/eversion, but jerk present
Sciatic: everything gone
Common peroneal: eversion gone, but jerk and inversion present (because tibial does this)
Unmyelinated nerves
Small fibre nerves
Pain and autonomic signals
What does Nerve Conduction Studies test?
Large Myelinated fibres record best
Aids localisation
Can’t test small fibres or autonomic fibres
Motor: anterior horn cell to muscle (Includes NMJ)
Sensory: skin to dorsal root ganglia