Upper limb
Ulna
Ulna
- Origin
- Medial long bone of the forearm (pinky side); articulates with trochlea of humerus and radial head
- Insertion
- Insertion site for triceps brachii (olecranon), brachialis, anconeus, and deep flexors of wrist and digits
- Function
- Acts as stabilizing axis for the forearm and primary hinge of the elbow joint
- Innervation
- Ulnar, median, and radial nerves
- Movement & chain
- Hinge flexion and extension at the elbow; fixed axis for radius rotation during pronation/supination
- Palpation
- Olecranon (tip of elbow), posterior subcutaneous border, and ulnar styloid process are easily palpated
- Clinical
- Olecranon fracture; Monteggia fracture-dislocation; ulnar nerve entrapment at the elbow (cubital tunnel syndrome); olecranon bursitis
- Segmental innervation
- C5–T1
- In clinical practice
- Olecranon landmark for joint aspiration and differential diagnosis of elbow trauma
- Region in the model
- Upper limb