Structure:
The upper extremity is made up with the bones of the shoulder, called the
pectoral girdle, to which is attached
the humerus of the upper arm, the radioulna
and of the forearm, and the bones of the front hands.
Function:
The upper extremity provides a major tool for exploration of the environment.
The upper extremity is attached to the trunk at the sternum by the anterior
clavicles and coracoid bones, but otherwise,
it is only attached by muscles and ligaments. The elbow joint with the
humerus and the radioulna, is fixed, restricting the rotation capability
of the frog. This architecture enables the great mobility of the upper
extremity. In tetrapods, animals that ambulate
on both the upper and lower extremities, the upper extremity may be less
versatile in its' functions. For example, in frogs
and toads, a major function is to cushion their fall after a leap by
landing on the upper extremity before the lower
extremity reaches the landing surface. In humans, it permits grasping,
pulling, pushing, turning, striking, and dexterous movements,
too.
