Cross-sectional view of the upper arm at the level of the mid-humerus
Course of the nerves through the upper arm.
lateral and medial cord–> lateral to axillary artery–> descends through arm adjacent to brachial artery–> gradually crosses anterior to artery and ends medial to artery at cubital fossa –> cubital fossa–>under the two heads of pronator teres and fibrous arch of FDS–> supplies most muscles of anterior forearm–> runs down arm between FDS and FDP–> enters hand under flexor retinaculum lateral to flexors and medial to FPL –> supplies LOAF
Anterior interosseus nerve runs on IO membrane between FDP and FPL and deep to pronator quadratus
Medial cord –> descends in medial arm–> passes posterior to medial epicondyle –> goes under two heads of FCU–> supplies FCU, ulna part of FDP muscles–> goes down ulnar aspect of forearm between FCU and FDP becomes superficial distally –> supply most muscles of hand – deep supplies hypothenar muscles and adductor pollicis, superficial supples skin and palmaris brevis.
Posterior cord –> posterior to axillary artery–> supplies triceps–> posterior to humerus in radial grove with deep brachial artery, between lateral and medial heads of triceps–> perforate lateral intermuscular septum and passes anterior to Lateral epicondyle–> enter cubital fossa between brachioradialis and bracialis and divides into superficial(cutaneous) and deep(motor) radial nerves
Radial supplies brachioradialis, extensor carpi radialis longus and brevis and aconeus.
Deep branch – posterior interosseous nerve – supinator, ECU, EDM, ED, AbPL, EPL, EPB, Extensor indicis.
Superficial branch – four branches
Cutaneous branches to arm and forearm arise before radial grove.
Injury at radial head affects deep branch – no sensory loss, no wrist drop(ECRL) but affects all the muscles.
Exits by piercing corocobrachialis –> descend between biceps and brachialis — finish as Lateral cutaneous nerve of forearm.
Location – upper limb joint
Bones involved – ulna, radius and humerus
Type of joint – hinge synovial joint
Movements – flexion, extension
Bony congruance – very good between trochlea and its fossa and olecranon and its fossa.
Muscle – flexors – biceps, brachialis and brachioradialis. Triceps and aconeus for extension.
Ligaments – collateral ligaments very strong from epicondyles to annular ligament and coronoid and olecranon respectively. Annular ligament of radial head. Medial collateral is triangular and lateral has 4 components including radial and ulna component.
Other – radial head articulates with the radial notch on ulna, fibrous joint capsule. Superior radio-ulna joint communicates with elbow joint. Elbow joint capsule attaches to annular ligament.
Blood supply – anastamosis between brachial and radial and ulnar arteries.
Nerves – musculocutaneous, radial and ulnar
X-ray of the elbow.
At what age does each bone get ossification centre
Capitalum – 2
Radial head – 4
Internal epicondyle – 5
Trochlea – 9
Olecranon – 9
External epicondyle – 11
Condyles – capitalum and trochlea
Anterior surface of elbow
Roof – bicipital apponeurosis, skin and fascia – median cubital vein runs here
Floor – brachialis and supinator
Superiorly – an imaginary line between the epicondyles.
Medially – lateral border of pronator teres
Laterally – medial border of brachioradialis
median nerve leaves between the two heads of pronator teres
Brachial artery bifurcates into radial and ulnar arteries at the apex of Cubital fossa
Radial nerve – splits to deep and superficial