ulna
bone that together with the radius forms the forearm
Source: Noland, George B. 1983. General Biology, 11th Edition. St. Louis, MO. C. V. Mosby ...
The ulna (Figs. 212, 213) is a long bone, prismatic in form, placed at the medial side of the forearm, parallel with the radius. It is divisible into a body and two extremities.
ulna
The posterior of two bones of the forearm of tetrapods. The ulna articulates proximally with the humerus and distally with the carpals.
Ulna Elbow.
ultimate causation (factors) Those aspects of behavior that are concerned with why the behavior evolved and its functional significance in an ecological context.
Hinge joints, such as the elbow (between the humerus and the ulna). These joints act like a door hinge, allowing flexion and extension in just one plane.
Pivot joints, such as the elbow (between the radius and the ulna).
ulna: upper extremity (olecranon, coronoid process, tuberosity, radial notch, semilunar notch) - body of ulna - lower extremity (styloid process)
radius: upper extremity (tuberosity) - body - lower extremity (ulnar notch, styloid process) ...
Primates have modifications to their ulna and radius (bones of the lower arm) allowing them to turn their hand without needing to turn their elbow. Many primates can also swivel or turn their arms at the shoulder.
When mice were bred with homozygous mutations for both HoxA11 and HoxD11, they were born with neither radius nor ulna in the forelimbs.
Below a joint (elbow or knee), both limbs have a pair of bones (radius and ulna in the arms; tibia and fibula in legs) that connect to another joint (wrist or ankle). The carpals makeup the wrist joint; the tarsals are in the ankle joint.
 See also: Human, Radius, Trans, Bone, Class
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