Antebrachium- Anterior and Posterior

3 joints within one capsule: 1. Humero-ulnar 2. Humero-radial 3. Proximal Radio-Ulnar

-Articulation of trochlea of humerus with trochlear notch of ulna -Modified sellar joint -Allows flexion/extension

-Articulation of the concave proximal surface of the radial head with the convex surface of the capitulum of the humerus -Ovoid joint -Allows flexion/extension, and pronation of radius -> pronation/supination

-Articulation of the periphery of radial head with the fibro-osseous ring formed by radial notch of ulna and annular lig. -Periphery of radial head presents modified convex surface -Radial notch of ulna presents concave surface -Allows radial head to turn/spin/rotate --> Pronation/Supination

-Associated with Proximal Radio-ulnar Joint -Articulation of convex peripheral surface of ulnar head with concave surface of ulnar notch of radius

-Typically thin, lined with synovial membrane -Envelopes humeroulnar, humeroradial, and proximal radioulnar joints

Joint is displaced in medial direction, the distal end of the limb is lateral relative to the position of the joint Typically~15 degrees

Joint is displaced in lateral direction, the distal end of the limb is medial relative to the position of the joint

Medial Collateral Lig: Anterior Fibers Posterior Fibers Transverse Fibers Lateral Collateral Lig Radial Collateral Lig. Lateral Ulnar Collateral Lig.

-From ant aspect of med humeral epicondyle to medial aspect of coronoid process -Strongest, stiffest band -Most fibers tight in full extension -Some stability

-From post aspect of medial humeral epicondyle to medial surface of olecranon -Tight in extreme elbow flex -Reists valgus stress

-From olecranon process to coronoid process -Little stability

-From split of Lateral Collateral Ligament -Fibers blend with Annular Ligament

-From split of Lateral Collateral Ligament -Fibers attach to supinator crest of ulna -All resist varus force

-Fibrous CT membrane that connects interosseous borders of radius and ulna -Connects without limiting pronation and supination -Provides SA for muscle attachment -Collage bundles directed distal/medial from radius to ulna allows for transfer of forces from radius to ulna and hand-radius-ulna-humerus -Maintains relationship between radius and ulna