anatomy of nerve injuries upper limb

Professor Emeritus Moira O’Brien

FRCPI, FFSEM, FFSEM (UK), FTCD

Trinity College

Dublin

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Anatomy of Nerve Injuries Upper Limb

Anatomy of Nerve Injuries

• Dermatomes• Myotomes• Nerves entrapped• Pierce muscle• Pierce fascia• Repetitive movements

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Dermatomes

• Skin

• Bones

• Muscles, tendons

• Nerves

• Blood vessels

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Cutaneous Supply MOB TCD

Extrinsic Factors

• External forces• Fibro-osseous tunnels tether

the nerve • Oedema• Callus formation as a result of

a fracture • External compression due to

specific movements• Mechanical compression • The nerve is tender at the site

of compression

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• Fibrous bands

• Accessory muscles

• Spurs

• Narrow notches

• Anatomical variations of the nerve itself

• The most common symptom complex involves the lower trunk of the brachial plexus C8,T1

• With pain and paresthesia along the medial border of the limb

Extrinsic Factors MOB TCD

Congenital and structural anomalies include:

• Cervical ribs• Scalenus anterior syndrome• Fibrous or fibro-muscular

bands


• Costoclavicular, where it may also be due to anatomical anomalies or structural changes, e.g. shoulder girdle depression

• Between the pectoralis minor and the coracoid process

• The shoulder is very mobile and the neurovascular structures may change direction by a full 180°

• The coracoid process and the pectoralis minor act as a fulcrum for the change in direction

• This is a potential site of compression


Costoclavicular Compression

• Costoclavicular compression is usually dynamic

• If you elevate the arm, the clavicle rotates at the sternoclavicular and acromioclavicular joints, narrowing the costoclavicular space

• This space will be further narrowed by retraction of the shoulders, particularly if you are carrying a heavy weight

• Deep inspiration elevates the first rib; this narrows the space even further

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Brachial Plexus

• Roots arise from Anterior Primary Rami

• C5• C6• C7• C8• T1• Contribution from C4

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• Roots unite to form trunks; posterior triangle of neck

• C5, C6 form upper trunk• C7 middle trunk• C8,T1 form lowest trunk• Branches arise mainly from

roots and cords• Only 1 from upper trunk

Brachial Plexus MOB TCD

• Roots between scalenus anterior and scalenus medius

• Trunks in the posterior triangle

• Divisions behind clavicle• Cords in axilla to lower

border of pectoralis minor


Branches From Roots

• Branch to phrenic nerve C5• Nerve to rhomboids or

dorsal scapular C5• Nerve to subclavius

C5,C6, accessory phrenic• Long thoracic nerve to

serratus anterior C5, C6, C7 along the side wall of thorax

• Kick or blow may affect rotation of scapula and winging of scapula

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Brachial Plexus Entrapment

• Compression of thoracic inlet

• Cervical rib• Scalenus anterior or

fibrous band• Back pack narrow

costoclavicular

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Suprascapular Nerve

• Upper trunk of brachial plexus • C5, C6 in the posterior triangle• Passes through suprascapular

foramen into the• Supraspinous fossa supplies

suprascapular muscle• Passes through the

spinoglenoid notch supplies infraspinatus muscle

• Articular to shoulder joint

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Blood and Nerve Supply

√

• At spinoglenoid notch only infraspinatus affected

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Cords of Brachial Plexus

• Outer border of first rib• Divisions unite to form

cords• Lateral, medial and

posterior cords, related to first and second parts of axillary artery

• End at lower border of pectoralis minor

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Lateral Cord of Brachial Plexus

Lateral cord gives off:• Musculocutaneous• Lateral pectoral• Lateral root of median nerve

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Medial Cord of Brachial Plexus

• Medial cutaneous of arm• Medial pectoral• Medial cutaneous of forearm• Medial root of median• Ulnar

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Posterior Cord of Brachial Plexus

• Axillary nerve • Upper subscapular nerve• Lower subscapular nerve,

subscapularis and teres major• Nerve to latissimus dorsi• Radial nerve

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Musculocutaneous Nerve

• Supplies and pierces coracobrachialis

• Passes between

brachialis and

biceps supplying them• Continues as

lateral cutaneous of forearm

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Lateral Cord of Brachial Plexus

• Lateral pectoral pierces the clavipectoral fascia and

• Supplies pectoralis major• Gives off the lateral root of

median nerve

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Axillary Nerve

• Posterior cord lower border of pectoralis minor

• Quadrilateral space• Upper lateral cutaneous nerve of

arm supplies skin over lower half of deltoid

• Nerve to deltoid• Nerve to teres minor• Injury results in loss of sensation

over the lower half of the deltoid• Weakness of the deltoid and the

teres minor

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Shoulder Relations

Anterior • subscapularis

Posterior • infraspinatus, teres minor

Superior • long head of biceps• supraspinatus

Inferior • axillary nerve

In abduction • long head triceps

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Shoulder Anterior Relations MOB TCD

Axillary Nerve

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Axillary Nerve Compression

• Dislocated shoulder• Quadrilateral space

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Radial Nerve

• In axilla• Posterior cord: lower

border of pectoralis minor, posterior to axillary artery

• Gives off posterior cutaneous nerve of arm

• Supplies and then passes between long and medial head of triceps

• Injury in axilla e.g. crutches, Saturday night paralysis

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• In spiral groove• Nerve to lateral and medial

head of triceps• Posterior cutaneous nerve of

forearm• Nerve to anconeus

Radial Nerve MOB TCD

Radial Nerve - Spiral Groove

• Lies between brachioradialis and brachialis and the extensor carpi radialis longus

• Pierces lateral intermuscular septum

• Brachioradialis and lateral border of brachialis supplies them

• Extensor carpi radialis longus

• Divides into superficial branch

• Posterior interosseus nerve

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Posterolateral

• Lies below head of radius• Below lateral epicondyle• Deep or posterior interosseous

supplies and then passes between two heads of supinator

• Supplies the extensor carpi radialis brevis

• Extensors from the lateral epicondyle and all the deep extensors of forearm

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Posterior Relations

• Superficial lies lateral to radial artery in upper two thirds of forearm

• Passes posterior to dorsum• Pierces deep fascia• Supplies posterior aspect of

forearm• Skin of dorsum posterior

aspect of radial three and half fingers

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Radial Nerve in Forearm

• Deep or posterior interosseus nerve supplies and then pierces supinator

• Muscles of posterior compartment of forearm

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Radial Nerve

• Extensor digitorum communis, extensor digiti minimi extensor carpi ulnaris

• Abductor pollicis longus• Extensor pollicis brevis• Extensor pollicis longus• Extensor indicis

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Elbow Nerve Compression

• Radial tunnel syndrome• Posterior interosseous

nerve syndrome• Cubital tunnel syndrome• Pronator syndrome• Anterior interosseous

nerve syndromeBehr & Altchek, 1997

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Tennis Elbow Extensor Muscles

• Extensor carpi radialis brevis in most cases

• Anterior edge of extensor digitorum communis 30% less frequently

• Extensor carpi radialis longus• Extensor carpi ulnarisNirschl, 1993

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Posterior Relations of Elbow

• Triceps• Anconeus• Olecranon bursa• Ulnar nerve posterior to

medial epicondyle• Common extensor origin

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Posterior Interosseous MOB TCD

Deep Branch of Radial Nerve Posterior Interosseus

• Supplies and then enters forearm between the two heads of supinator

• Extensor carpi radialis brevis• Extensor digitorum communis• Extensor indicis• Extensor digiti minimus • Extensor carpi ulnaris• Extensor pollicis longus and brevis• Abductor pollicis longus

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Radial Nerve in Forearm and Hand MOB TCD

Anatomical Snuffbox

Medial• Abductor pollicis longus• Extensor pollicis brevis• Both involved in De Quervain’s

syndrome Posterior • Extensor pollicis longusFloor • Distal end of radius and scaphoid • Radial arterySuperficial• Radial nerve

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Nerves in Forearm

• Posterior interosseus nerve• Supinator• Median nerve• Pronator teres• Ulnar nerve• Flexor carpi ulnaris

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Median Nerve

Median nerve• Lower border of pectoralis minor • Union of the two roots of median• Anterior to axillary artery at first• Then lateral and medial to

brachial artery• Passes behind bicipital

aponeurosis• No branches in arm• Pronator teres

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Median Nerve in Forearm

• Median gives off branches to flexor tendons

• Pronator teres, flexor carpi radialis

• Pronator teres • Flexor digitorium superficialis• Passes between two heads of

pronator teres

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Median Nerve MOB TCD

• Passes deep to flexor digitorum superficialis

• Gives off• Anterior interosseous, supplies

flexor pollicis longus• Radial one or two tendons of

flexor digitorum profundus• Pronator quadratus


• Median passes deep to flexor digitorum superficialis

• At wrist, posterolateral to palmaris longus

• Gives off the superficial palmar branch

• Passes superficial to flexor retinaculum

• Main nerve goes deep to retinaculum


• No loss of sensation over skin of palmar aspect of thenar eminence

• Loss over palmar aspect radial 3.5 fingers

• Wasting of thenar eminence particularly abductor pollicis brevis

Carpal Tunnel MOB TCD

Wrist and Carpal Tunnel MOB TCD

• Median distal border gives off motor branch to abductor pollicis brevis

• Flexor pollicis brevis• Opponens pollicis• Unipennate lumbricals• Cutaneous branches to radial

three and half and skin over the dorsum of corresponding fingers

Wrist and Carpal Tunnel MOB TCD

Injury at Elbow

• Loss of sensation over skin of palmar aspect of thenar eminence

• Palmar aspect of radial three and half fingers

• Wasting of thenar eminence

• Weakness of superficialis and one or two of profundus tendons

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Median Nerve Lesion MOB TCD

Compartment Syndrome

• Forearm is the most common site of compartment syndrome

• Anterior compartment of the forearm may compress median nerve

• Posterior compartment• Mobile wad may be

altered sensation over the dorsum

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• Windsurfing may cause compartment syndrome in flexor compartment

• Compression of median nerve

Compartment Syndrome MOB TCD

Blood and Nerve Supply MOB TCD

Ulnar Nerve

• Lower border of pectoralis minor from medial cord

• Medial to brachial artery• Midway down• Pierces medial intermuscular

septum, into posterior compartment• Passes between two heads of

flexor carpi ulnaris• Behind medial epicondyle to enter

anterior compartment of forearm• No branches in the arm

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Ulnar Nerve MOB TCD

• Supplies and then runs between flexor carpi ulnaris and flexor digitorum profundus

• Supplying medial two or three tendons of flexor digitorum profundus

• 5 cm above wrist gives off the dorsal cutaneous branch skin of medial one and half fingers

Ulnar Nerve MOB TCD

• Passes superficial to flexor retinaculum with artery on lateral side, Guyons’ tunnel

• Supplies palmaris brevis• Muscles of hypothenar

eminence• Bipennate lumbricals• Palmar and dorsal interossei • Ends in adductor pollicis

Ulnar Nerve MOB TCD

Ulnar Nerve MOB TCD

Compression at wrist affects skin over palmar small finger, half of the ring finger and hypothenar muscles, not skin over the dorsal aspect.

Ulnar Nerve MOB TCD

• Rounded elbow in throwing sports

• Javelin • Discus puts tension on ulnar

nerve at elbow• Electric shock along course of

nerve• Late result of supracondylar

fracture

Ulnar Nerve Injury MOB TCD

Hamate

• Hook of hamate may fracture if palm hits a wall

• Damage deep branch of ulnar • Wasting of adductor pollicis• 1st dorsal interossei

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Ulnar Nerve Paradox

• More deformity with an injury at wrist than elbow

• Wasting of first web and guttering due to wasting of interossei and bilateral lumbricals

• Hyperextension of metacarpophalangeal joints

• Flexion of proximal and distal interphalangeal joints

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Grips MOB TCD

Test for Ulnar Neuritis

• Tap ulnar nerve on posteromedial aspect of medial epicondyle

• Completely flex elbow and hold for five minutes

• Positive is tingling along nerve

Anderson & Hall, 1995

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Test for Medial Epicondylitis

• Stabilise flexed elbow• Palpate medial epicondyle• Slowly supinate the forearm• Extend wrist and elbow, while

patient resistsAnderson & Hall, 1995

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Elbow

• Biceps brachii Musculocutaneous C5,C6• Brachialis Musculocutaneous C5,C6• Triceps Radial C6, C7, C8• Pronator teres Median C6,C7• Supinator Posterior interosseous C5,C6Anderson & Hall, 1995

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anatomy of nerve injuries upper limb

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