Muscles + Ligaments

Flexors of the upper arm and forearm

• Flexors = muscles that cause flexion

• Extensors = muscles that cause extension

Upper arm flexors:

• Coracobrachialis

• Anterior deltoid

• Biceps brachii

• Pectoralis major

Elbow flexors:

• Biceps brachii

• Brachialis

• Brachioradialis

• Pronator teres (weak flexor)

Extensors of the upper arm and forearm

• Extensors = muscles that cause extension

Extensors of upper arm:

• Latissimus Dorsi

• Deltoid (posterior fibres)

• Teres Major

• Long head of biceps brachii

Extensors of forearm:

• Triceps brachii

• Anconeus

Muscles that pronate and supinate the forearm

The two muscles located on the anterior forearm that pronate the forearm are:

1. Pronator teres

2. Pronator quadratus

The one muscle located on the posterior forearm that supinates the forearm is:

1. Supinator

Main concepts of supination vs flexion muscles

The supinator muscle’s main function is to supinate the forearm. This can be actioned with the elbow in any position of flexion or extension. The supinator can also work synergistically with the biceps brachii to produce powerful supination if required. However, the biceps brachii muscle cannot supinate the forearm when the elbow is extended, only when it is flexed

Elbow joint classification + articulation surfaces

Classification:

• Synovial Hinge

Articulation Surfaces:

1. Trochlea of humerus with the trochlear notch of ulna

2. Capitulum of humerus with head of radius

Ligaments of the elbow

• Function of elbow ligaments: Stabilisation

Primarily 3 ligaments:

1. Medial (ulnar) collateral (MCL)

2. Lateral (radial) collateral (LCL)

3. Annular ligament

MCL & LCL provides:

• Varus and valgus stability

• Enable rotation

Annular ligament = stabilises radial head in radial notch

(Varus and valgus stability refer to the ability of a joint, like the knee or elbow, t resist forces that push it inward (valgus) or outward (varus)

Ulnar collateral ligament

• From: Medial epicondyle of humerus

• To: Coranoid process of the ulna (anteriorly) and olecranon (posteriorly)

• Action: enables rotation

Radial collateral ligament

• From: Lateral epicondyle

• To: Annular ligament

Valgus and Varus stresses at the elbow

Annular ligament

• Stabilises radial head in radial notch

• Both ends attach to the anterior and posterior margins of the radial notch of the ulna- hereby surrounding the radial head and neck

• Fibrous joint capsule also attaches as well as radial collateral ligament

Quadrate ligament

Olecranon and elbow bursa’s

• Thin, fluid-filled sac- located at olecranon (elbow bony tip).

• Function: Helps reduce friction between bone and soft tissue e.g. skin etc

• Olecranan bursitis = inflammation of a bursa

Borders of the antecubital fossa

BORDERS of ANTECUBITAL FOSSA:

• Lateral: brachioradialis muscle

• Medial: pronator teres muscle

• Superior: Imaginary line between the epicondyles of the humerus

• Roof: Skin & Fascia

• Base: proximally by the brachialis, and distally by the supinator muscle.

• Apex: Where the lateral and medial