Lecture 6 Comparative anatomy of the Elbow and Forearm

Functions of the Elbow in humans The set if the elbow allows for the hand to be placed in a position that makes it ideal for manipulation • Mostly non-weight supporting, and very important in throwing Bones Distal humerus- articulating parts

Capitulum - Articulates with radial head - Almost half a sphere

Trochlea - Like a pulleu - Articulates with trochlea notch of the ulna

Distal humerus – non articulating parts

Medial epicondyle - Blunt medial projection - Anterior surface has attachment for fore arm flexors

Lateral epicondyle - Lateral non-articulating part - Attachment for forearm extensors on lateral part

Distal humerus – fossae Olecranon fossa On posterior surface contains the olecranon of the ulna

Coronoid fossa Anterior surface contains ulna coronoid process

Radial fossa Shallow fossa anteriorly, contains the radius in flexion.

Radius Proximal end Lateral bone in the forearm - Proximal end includes a head, neck and radial tuberosity - Head discoid and like a shallow cup, articulates with the capitulum - Neck is a constriction blew the head

Distal end - Interosseous border for attachment of interosseous membrane - Styloid process sharp projection on lateral side of distal radius - Dorsal tubercle a large tuberosity on the posterior surface of the distal end.

Ulna

Proximal end

- Olecranon hook like projection which enters the humeral olecranon fossa - Trochlea notch for articulation with the trochlea od the humerous - Coronoid process projects anteriorly distal to the olecranon - Radial notch – small oval depression on lateral side of coronoid process

Distal end

- Shaft sharp lateral border attachement foe Interosseous membrane - Styloid process on the distal end - Radial articulation distal rounded articulation that conforms to the ulna notch of the radius.

Joints Elbow joint • Humero-ulna, synovial, hinge • Humero-radial, synovial, sliding

Radio-ulnar joints • Superior, synovial, pivot • Inferior, synovial, pivot

Elbow joint Humero-ulnar joint – trochlear of humerus and trochlear notch of ulna

Humero-radial joint – capitulum of humerus and head of radius

Radio-ulnar joints

Superior radio-ulnar - head of the radius and the radial notch of the ulna

Inferior radio-ulnar – the ulna notch at lower end of radiud and facet on lateral side of ulna.