The ulna connects directly to the humerus at the elbow joint and provides a stable anchor point for the powerful muscles that extend the forearm. Around the age of 18 to 25, this cartilage ossifies and hardens into solid bone, marking the end of vertical growth.
Radius and Ulna Anatomy Functions and Structural Differences
A common injury involves a fracture of the radius near the wrist, known as a Colles' fracture, while ulna fractures often occur in the middle of the shaft. Injuries to these growth plates can affect the final length and alignment of the forearm bones.
The ulna is located on the medial side (pinky finger side) and is longer than the radius, while the radius sits on the lateral side (thumb side) and allows for significant rotational movement. The head of the radius rotates within a ligament ring, enabling the palm to face up (supination) or down (pronation).
Radius and Ulna Anatomy Functions and Structural Differences
Development and Growth Plates In children and adolescents, these two bones are separated by a layer of cartilage known as the growth plate. To return the hand to a palm-up position, the radius uncrosses in a motion called supination.
More About How many bones in the lower arm
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More perspective on How many bones in the lower arm can make the topic easier to follow by connecting earlier points with a few simple takeaways.
