Humerus,radius and ulna



Humerus


This is the bone of the upper arm.


The head sits within the glenoid cavity of the scapula ,forming the shoulder joint.

Distal to the head are two roughened projections of bone, the greater and lesser tubercular sulcus,occupied by one of the tendons of the biceps muscle.


The distal end of the bone presents two surfaces that articulate with the radius and ulna to form the elbow joint .



Ulna and radius .


These are the two bones of the forearm.


The ulna is longer than medial to the radius and when the arm is in the anatomical position, i.e. with the palm of the hand facing forward,  the two bones are parallel.

They articulate with the humerus at the elbow joint, the carpal bones at the wrist joint and with each other at the proximal and distal radioulnar joints.

 In addition , an interosseous membrane, a fibrous joint, connects the bones along their shafts, stabilizing their association and maintaining their relative positions despite forces applied from the elbow or wrist.

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