Ulna
The ulna is the medial bone of the forearm, extending from the elbow to the wrist. It is the main bone of the elbow joint and provides stability during forearm movements.
Key Features
Articulations
- •Elbow joint (trochlear notch with trochlea) - hinge
- •Proximal radioulnar joint (radial notch with radial head) - pivot
- •Distal radioulnar joint (head with ulnar notch of radius) - pivot
Muscle Attachments
Clinical Relevance
Olecranon fractures are common from direct trauma or falls on the elbow. Nightstick fracture is an isolated ulnar shaft fracture from blocking a blow. Monteggia fracture is proximal ulna fracture with radial head dislocation.
Ulna FAQs
Common questions about this bone
The olecranon is the bony prominence at the back of the elbow, forming the tip of the elbow when bent. It is the proximal end of the ulna and serves as the insertion point for the triceps muscle.
A Monteggia fracture is a fracture of the proximal ulna shaft combined with dislocation of the radial head. It requires recognition of both injuries for proper treatment.
The ulna provides most of the elbow joint stability. The trochlear notch wraps around the trochlea of the humerus, creating a stable hinge joint that allows only flexion and extension.
A nightstick fracture is an isolated fracture of the ulnar shaft, typically caused by a direct blow to the forearm (as when blocking an attack with a stick). It is named for the defensive mechanism.