Brachial plexus
- The brachial plexus has the following parts
- Roots which are the anterior rami of C5678 and T1
- Trunks - The roots join to form upper, middle & lower trunks
- Divisions of the three trunks and give out no branches
- Cords - The divisions unite to form cords
- Cords are lateral to the first part of axillary artery and are
mediolateral and posterior to the second part of axillary artery
Axillary nerve (C5,6)
- Arises from the posterior cord of the brachial plexus
- Passes through the quadrangular space and winds around the neck of
humerus
- Muscles supplied are deltoid and teres minor
Axillary nerve palsy
- May occur as a result of anterior dislocation of the shoulder joint
- Motor impairment - abduction of arm
- Sensory impairment - sensation reduced over deltoid
Radial nerve (C5,6,7,8,T1)
- Arises from posterior cord of brachial plexus
- Passes along with the Profunda brachial artery
- Travels through the radial groove on the posterior aspect of humerus
- Muscles supplied
- Arm - triceps
- Forearm - all muscles of the Extensor compartment
- Hand - none
Radial nerve palsy
- May be damaged in fracture of shaft of humerus as it passes through
the spiral groove
- Appearance - wrist drop
- Motor impairment - inability to extend the elbow, wrists and fingers
- Sensory impairment - lower posterior part of arm, forearm and the
anatomical ‘snuff box’
Median nerve (C5,6,7,8,T1)
- Has two roots - medial and lateral
- Medial root arises from Medial cord of brachial plexus
- Lateral root from the lateral cord of brachial plexus
- Passes through the Carpal tunnel
- Muscles supplied
- Arm - none
- Forearm - all muscles except Flexor carpi ulnaris and medial half
of flexor digitorum profundus
- Hand - muscle of thenar eminence and lateral two lumbricals
Median nerve palsy
- The clinical features of a median nerve palsy are
- Appearance - thenar eminence wasted with ape-like thumb (adducted
and rotated)
- Motor impairment - wrist and finger flexion at interphalangeal
joints (except 4th and 5th DIP joints)
- Flexion of index and middle fingers at metacarpophalangeal joints
(as only lateral two lumbricals supplied by it)
- Inability to abduct and oppose thumb
- Sensory impairment:- lateral half of palm and lateral three and half
fingers (variable in up to 50%)
Ulnar nerve (C8 T1)
- Arises from medial cord of brachial plexus
- Passes behind the medial epicondyle of humerus
- Passes in front of the flexor retinaculum at the wrist
- Muscles supplied
- Arm – none
- Forearm - Flexor carpii ulnaris and medial half of flexor
digitorum profundus
- Hand - hypothenar muscles, all interossei (4 dorsal + 4 palmar),
3rd and 4th lumbricals, adductor polices, palmaris brevis
Ulnar nerve palsy
- The clinical features of an ulnae nerve palsy are
- Appearance - hypothenar wasting and claw-hand deformity
- Motor impairment - wrist and fourth/fifth finger flexion at distal
interphalangeal joints
- Adduction and abduction of fingers
- Adduction of the thumb
- Sensory impairment: - medial half of palm and medial one and half
fingers
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