Cross-sectional view of the upper arm at the level of the mid-humerus
Course of the nerves through the upper arm.
Median
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
Ulnar
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.
Radial
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.
Musculocutaneous
Exits by piercing corocobrachialis –> descend between biceps and brachialis — finish as Lateral cutaneous nerve of forearm.
Elbow joint.
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.
AP Xray Elbow
Lateral Xray Elbow
At what age does each bone get ossification centre
(C-R-I-T-O-E)
Capitalum – 2
Radial head – 4
Internal epicondyle – 5
Trochlea – 9
Olecranon – 9
External epicondyle – 11
Distal Humerus
Supraepicondylar ridge
Epicondyles
Condyles – capitalum and trochlea
Radial fossa
Coronoid fossa
Olecranon fossa
Cubital fossa
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
Contents
median nerve leaves between the two heads of pronator teres
Brachial artery bifurcates into radial and ulnar arteries at the apex of Cubital fossa
Biceps tendon
Radial nerve – splits to deep and superficial