The ulna is one of two bones in your forearm, the other being the radius. It's a long bone located on the medial side of your forearm (pinky finger side) when your arm is in the anatomical position. The ulna plays a crucial role in arm, wrist, and hand movement and provides support for various muscles and tendons.
Anatomy and Location
- Longer Bone: Contrary to some beliefs, the ulna is actually the longer of the two forearm bones.
- Elbow Joint: The ulna forms a vital part of the elbow joint, articulating with the humerus (upper arm bone).
- Radius Articulation: It also connects with the radius at both its proximal (elbow) and distal (wrist) ends.
- Medial Position: Its location is consistently described as medial, meaning closer to the midline of the body.
Cleveland Clinic describes the ulna as helping you move your arm, wrist, and hand, and supporting many muscles and tendons. TeachMeAnatomy reinforces its medial location alongside the radius.
Function and Clinical Significance
The ulna's primary functions include:
- Movement: Facilitating the complex movements of the arm, wrist, and hand.
- Muscle Attachment: Providing attachment points for numerous muscles.
- Joint Stability: Contributing to the stability of both the elbow and wrist joints.
Injuries to the ulna, such as fractures, are common. Johns Hopkins Medicine notes that isolated ulnar fractures can often be treated with a cast. Injuries to the ulnar collateral ligament (UCL), discussed by Johns Hopkins Medicine, can lead to significant elbow pain and functional limitations.
The ulna's shape also contributes to the overall forearm's structure, specifically its curvature or "bow." A study (PubMed) detailed the normal ulnar bow in adults.
In Summary
The ulna is a vital bone of the forearm, crucial for movement and structural integrity. Its articulation with the humerus and radius allows for the wide range of motion in the upper limb. Understanding its anatomy and function is essential for diagnosing and treating various arm and hand injuries.
