Motor Localisation: Myotomes & Peripheral Nerves

HomeA Guide to the MRCP PACES ExaminationStation 3 (Neurology)

Motor Localisation: Myotomes & Peripheral Nerves jenweiying 2018-01-30T16:37:22+08:00

UMN: spasticity, hyperreflexia, clonus, positive Babinski. No fasciculations, mild wasting
LMN: flaccid, hyporeflexic / arreflexic, absent Babinski. Severe wasting with fasciculations

Upper limb motor innervation:

Action	Muscle	Nerve	Root
Shoulder abduction	Deltoid	Axillary	C5
Elbow flexion	Biceps	Musculocutaneous	C5,6
Elbow extension	Triceps	Radial	C7,8
Wrist flexion	Flexor carpii	Median & ulnar	C6,7
Wrist extension	Extensor carpii	Radial	C7,8
Finger flexors	FDP, FDS	Median & ulnar	C8,T1
Finger extensors	Extensor digitorum	Posterior interosseous	C7,8
Finger abduction	Dorsal interossei	Ulnar	T1
Finger adduction	Palmar interossei	Ulnar	T1
Thumb abduction	Abductor pollicis brevis	Median	T1
Thumb adduction	Adductor pollicis	Ulnar	T1

Lower limb motor innervation:

Action	Muscle	Nerve	Root
Hip flexion	Iliopsoas	Femoral	L1,2
Hip adduction	Hip adductors	Obturator	L2,3
Hip abduction	Gluteus minimus, medius	Superior gluteal	L4,5
Hip extension	Hip extensors	Inferior gluteal	L5,S1
Knee extension	Quadriceps	Femoral	L3,4
Knee flexion	Hamstrings	Sciatic	L5,S1
Ankle dorsiflexion	Tibialis anterior	Deep peroneal	L5,S1
Ankle plantarflexion	Gastrocnemius	Tibial	S1,2
Foot inversion	Tibialis posterior	Tibial	L4,5
Foot eversion	Peroneus longus	Superficial peroneal	L5,S1
Toe extension	EHL	Deep peroneal	L5,S1

Reflexes:

Biceps: C5,6
Supinator: C6,7
Triceps: C7,8
Knee: L3,4
Ankle: S1,2