Elbow Joint

Elbow Complex •

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Elbow complex consists of the elbow joint (humeroulnar and humeroradial) and the proximal and distal radioulnar joints Elbow joint is a complex joint of hinge variety Is a uniaxial diarthrodial joint with 1° freedom of movement Flexion/extension occur in saggital plane around a coronal axis The proximal and distal radio ulnar joints are linked and function as one unit Rotation (pronation and supination) occur in a transverse plane around a longitudinal axis

Humeroulnar and humeroradial articulations: Articulating surfaces: Humerus: • Hour glass shaped trochlea (humeroulnar)– torchlear groove, coronoid fossa • Capitulum (humeroradial) – radial fossa • Olecranon fossa

Radius: • Head of radius • Articulates with the capitulum

Ulna: • Trochlear notch • Trochlear ridge

Articulation: • Articulation between ulna and humerus occurs primarily as a sliding motion of trochlear notch of ulna on the trochlea

In extension olecranon process enters the olecranon fossa In flexion coronoid process reaches the coronoid fossa

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Articulation between radial head and the capitulum involves sliding of concave radial head on the convex capitulum

1.In full extension no contact between the capitulum & radial head 2.During flexion the rim of the radius slides in the capitulotrochlear groove and in full flexion reaches the radial fossa

Capsule: • Humeroulnar and humeroradial and superior radioulnar joint are enclosed in a single joint capsule • Capsule is fairly large loose and weak anteriorly and posteriorly but ligaments reinforce side ways

Ligaments: Medial( ulnar) collateral ligament: • Consists of three parts anterior ,posterior, transverse Lateral(radial)collateral ligament:

Axis of Rotation • The axis of the joint is relatively fixed and passes through the center of the trochlea and the capitulum bisecting the longitudinal axis of shaft of humerus

Carrying angle : • In anatomic position, the long axis along the shaft of the humerus and the long axis of the forearm form an acute angle medially at the elbow. The angulation is due to the incongruency of the articulating surfaces • It is about 5° in men and 10 - 15° in women • An increase in the carrying angle is abnormal Cubitus valgus • Carrying angle disappears when the arm is pronated and the elbow is in extension or when the elbow is fully flexed against the forearm

RANGE OF MOTION : Depends on: • Type of motion: • Active ROM is usually less than passive ROM • This is due to the bulk of the contracting muscles • With the forearm supinated active elbow flexion is 135-145° • Passive elbow flexion is 150-160° • Position of the forearm: • In pronation or mid way between prone and supination the range of elbow flexion is less as compared to when the forearm is supinated

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Position of the shoulder: Two joint muscles (like biceps and triceps) which cross shoulder & elbow may become actively/passively insufficient Passive tension in the triceps with shoulder flexion limits elbow flexion Simultaneously the biceps looses tension as it shortens over both the joints Passive tension in the biceps with shoulder hyperextension limits elbow extension