SURGICAL ANATOMY OF UPPER LIMB NERVES AND PLEXUS

bydr PiRAH KORAI

resident neurosurgeryAKUH KARACHI

OBJECTIVES

OUTLINES

Brachial plexus

Main branches

Individual nerves with their clinical view

Brachial Plexus Injury

Obstetric brachial plexus palsyInjury to all or portion of a child brachial plexus

occurring at that time of the delivery.Excessive lateral traction on the head so that the

head is pulled away from the shoulder.Divide into :Erb’s Duchenne PalsyKlumpkee’s Palsy

Erb’s Duchenne PalsyInvolving upper roots (C5, C6 and C7)Affecting the musculature of the upper armShows the “waiter tips” posture of the

paralyze limb.The arm lies medial rotation at the side of

the chestThe elbow is extended (paralyzed C5, C6)Forearm is pronatedWrist and digits are flexed

Erb’s Duchenne Palsy

This posture occurs because of paralysis and atrophy of:

DeltoidBiceps brachiiBrachialisbrachioradialis

Klumpke’s PalsyRare

Involving lower root (C8 and T1)

Affecting forearm and hand: paralysis and atrophy of the small hand muscles and flexor of the wrist.

Claw hand

Brachial Plexus 5 main nerves arise from brachial plexus:

1. Axillary nerve C6-C72. Musculocutaneous nerve C5-6-73. Radial nerve C5-6-7-8 T14. Median nerve 5. Ulnar nerve C8-T1

AXILLARY NERVE

MUSCULOCUTANEOUS NERVE

Innervation of Musculocutaneous Nerve

Muscular innervation◦Supply coracobrachialis, biceps brachii and brachialis

Cutaneous innervation.◦Lateral cutaneous nerve of foream divide into

anterior and posterior branch.◦Anterior branch – skin of anterolateral surface of

forearm as far as ball of the thumb◦Posterior branch – skin of posterolateral surface of

forearm.

RADIAL NERVES

Radial NerveMotor innervationsTriceps brachii, anconeus, brachioradialis, supinator and

mostly posterior compartment extrinsic hand muscles.

Cutaneous innervation is provided by nerve that arise from

radial nerve.

◦ Posterior brachial cutaneous nerve

◦ Inferior lateral brachial cutaneous nerve

◦ Posterior antebrachial cutaneous nerve

◦ Superficial branch of radial nerve

Fracture of the humerus

Wrist Dropped

Functional motor deficitInability to extend the wrist (in case of injury at level of PIN, wrist extension is weak with radial deviation since ECRL innervation is intact)

Inability to extend the fingers at the MCP joints

Inability to extend and radially abduct the thumb

Weakness of grip strength d/t loss of mechanical advantage that wrist extension provides for grasp and power grip

RADIAL TUNNEL SYNDROME

•Most common causes include: ▪Tumors such as lipomas, ganglia

▪Rheumatoid synovitis

▪Septic arthritis ▪Vasculitis

Radial Tunnel Syndrome is a clinical diagnosis

Radial Tunnel

Syndrome

Tenderness over radial tunnel (lateral proximal

forearm, 3-4 cm distal to lateral epicondyle over the mobile wad)

Pain at ECRB origin with

resistance of middle finger

extension

Pain with resisted forearm

supination↑ Pain on

combined elbow extension, forearm

pronation, and wrist flexion

Radial Nerve Dermatomes

ULNAR NERVE

The ulnar nerve enters the anterior (flexor) compartment of the forearm through the two heads of flexor Carpi ulnaris and runs alongside the ulna bone.

Ulnar Innervated Muscles Forearm: Flexor Carpi Ulnaris (C7, C8, T1) Flexor Digitorum Profundus III & IV (C7, C8) Thenar: Hypothenar Muscles (C8, T1) Adductor Pollicis (C8, T1) Flexor Pollicis Brevis (C8, T1) Fingers: Palmer Interosseous (C8, T1) Dorsal Interosseous (C8, T1) III & IV Lumbricles (C8, T1) Digiti Minimi: Abductor Digiti Minimi (Quinti) (C8, T1) Opponens Dgiti Minimi (C8-T1) Flexor Digiti Minimi. : ( C8-T1)

Palmar cutaneous branch

Dorsal Cuntanous Branch

At the wrist, the ulnar nerve and artery lie in a canal formed by the pisiform bone medially and the hook of hamate laterally (Guyon’s canal).In this region the nerve divides into two

superficial and deep branches.The Superficial BranchThe Deep Motor Branch

CLINICAL APPLICATION OF ULNAR NERVE

Causes of injury of ulnar nerve according to level:

Upper arm : it get injured along with other structures like median N and brachial A.

Middle arm : Relatively protected

Distal arm or elbow : Dislocation of elbow Supracondylar or condylar fracture

Distal forearm and wrist : ( Most commonly injured) Gunshot wounds Laceration Fractures Dislocation

Tardy ulnar palsy : Malunited fracture of lateral humeral epicondyle children Displaced fracture of medial humeral epicondyle Dislocation of elbow Contusion Shallow ulnar groove Hypoplasis of humeral trochlea Recurrent subluxation or dislocation of ulnar nerve

Entrapment syndrome:

Arcade of Struthers: A thick fascial band that connects the medial head of the triceps to the intermuscular septum crosses the ulnar nerve at approximately 8 cm proximal to the medial epicondyle

Cubital tunnel: A fibrous sheath (Osborne’s ligament) laterally, and the head of the flexor carpi ulnaris posteromedially

Guyon’s canal: floor: the transverse carpal ligament, and also the flexor digitorum profundus, pisohamate and pisometacarpal ligaments, and the opponents digiti minimi. The roof : the palmar carpal ligament and the palmaris brevis, and distally passes ulnar to the hook of the hamate

•Tight fascia or ligament •Neoplasms•Rheumatoid synovitis•Aneurysm•Vascular thromboses•Anomolous muscles•Prologed direct pressure during surgery

Hand Dermatomes

Claw Hand Deformities

Ulnar nerve may be damaged in the groove behind the medial epicondyle either by trauma or entrapment.

Leads to partial or completely lost of muscular and sensory innervations.

The results of the ulna nerve lesion leads to the typical ‘claw hand’ deformities.

Due to lost of the power in the intrinsic hand muscles and unopposed actions of antagonistic muscles group.

Wasting of hypothenar eminence.There are ‘guttering between metacarpals, inability

to abduct the fingers or adduct the thumb.Sensory lost

MEDIAN NERVE

It supplies: Motor – all anterior (flexor) compartment of

forearm (except flexor carpi ulnari and ulnar half of the flexor digitorum profundus )

pronator teres & quadratus intrinsic hand muscles

-(LOAF;1,2 lumbricals, OP, FPB, APB) Sensory – skin of the palmar aspect of the thumb and the

lateral 3 ½ fingers and the distal ends of the same fingers and skin of distal phalanx on same finger

In the forearm, the median nerve directly innervates muscles in the superficial and intermediate layers:

•Superficial layer: Pronator teres, flexor carpi radialis and palmaris longus•.•Intermediate layer: Flexor digitorm superficialis.The median nerve also gives rise to the anterior interosseous nerve, which supplies the deep flexors:

•Deep layer: Flexor pollicis longus, pronator quadratus, and the lateral half of the flexor digitorum profundus (the medial half of the muscle is innervated by the ulnar nerve).In general these muscles perform pronation of the forearm, flexion of the wrist and flexion of the digits of the hand.© 2015-2016 TeachMeAnatomy.com [CC-BY-NC-ND 4.0]

Median nerve dermatomes

Carpal Tunnel SyndromeCompression median

nerve at the carpal tunnelPatient will experience

numbness, tingling, or burning sensation at the thumb, index, middle and radial half of the ring finger.

If untreated – weakness or atrophy of the thenar muscles.