Arm bones (= bones in arm) are part of the appendicular skeleton which includes the hands, arms and shoulder girdle (clavicle and scapula) and the feet, legs and pelvic girdle.
For the whole skeleton see the
human skeleton page.
This diagram of an anterior view of the right arm bones includes the shoulder joint, all of the arm itself, and also the wrist and hand bones. (It is based on a photo of a model of a human skeleton, hence the metal visible at the joints.)
The bones of the arm, wrist and hand labelled on the right include:
- the humerus (upper-arm bone and the following features on the humerus greater tubercle, head (of humerus), lateral epicondyle, medial epicondyle)
- the radius (lower-arm bone),
- the ulna (lower-arm bone),
- the 8 carpal bones
- the 5 metacarpal bones, and
- the 14 phalanges.
The upper-arm is the part of the arm from the shoulder to the elbow joint.
The humerus bone is the largest and longest bone in the arm. It consists of two extremities, the head of humerus at the top and a lower extremity on either side of which are the internal (medial) and external (lateral) condyles. The two extremities of the humerus bone are separated by the shaft of the humerus bone
The elbow joint is formed by the articulations between three bones, the humerus, the ulna, and the radius and comprises three parts:
- humeroulnar joint (ulna & humerus)
- humeroradial joint (radius & humerus)
- proximal radioulnar joint (radius & ulna)
Lower Arm (= Forearm):
The forearm is the part of the arm between the elbow and the wrist and comprises 2 long bones:
- The ulna is the larger and longer of these two bones. The upper extremity of the ulna forms part of the elbow joint. The narrowest part of the upper extremity of the ulna is the Olecranon process. The lower extremity of the ulna is very thin and excluded from the wrist joint by fibro-cartilage tissue.
- The radius is located on the outer (= lateral) side of the forearm. The upper extremity of the radius forms only a small part of the elbow joint but its lower extremity forms the main part of the wrist joint.
Wrist and Hand:
Most of the bones in the upper-limbs (arms) are in the wrist and hands. The bones of the hand and wrist are sometimes studied separately from those of the main length of the arm (i.e. the humerus, ulna and radius). The hand bones may be studied in more detail due to their complexity, while study of the arm bones may include more about the muscles attached to different parts of the humerus, ulna and radius and the actions of those muscles.
See also the elbow joint.