The coronoid process of the ulna is a triangular process projecting forward from the anterior proximal portion of the

ulna The ulna (''pl''. ulnae or ulnas) is a long bone found in the forearm that stretches from the elbow to the smallest finger, and when in anatomical position, is found on the medial side of the forearm. That is, the ulna is on the same side of t ...

Structure

Its ''base'' is continuous with the body of the bone, and of considerable strength. Anatomy Its ''apex'' is pointed, slightly curved upward, and in flexion of the

forearm The forearm is the region of the upper limb between the elbow and the wrist. The term forearm is used in anatomy to distinguish it from the arm, a word which is most often used to describe the entire appendage of the upper limb, but which in ...

is received into the

coronoid fossa of the humerus Superior to the anterior portion of the trochlea is a small depression, the coronoid fossa, which receives the coronoid process of the ulna during flexion of the forearm. It is directly adjacent to the radial fossa of the humerus The humerus ...

. Its ''upper surface'' is smooth, convex, and forms the lower part of the semilunar notch. Its ''antero-inferior'' surface is concave, and marked by a rough impression for the insertion of the brachialis muscle. At the junction of this surface with the front of the body is a rough eminence, the tuberosity of the ulna, which gives insertion to a part of the brachialis; to the lateral border of this tuberosity the

oblique cord The oblique cord is a ligament between the ulnar and radius bones in the forearm near the elbow. It takes the form of a small, flattened band, extending downward and lateralward, from the lateral side of the ulnar tuberosity at the base of the co ...

is attached. Its ''lateral surface'' presents a narrow, oblong, articular depression, the radial notch. Its ''medial surface'', by its prominent, free margin, serves for the attachment of part of the ulnar collateral ligament. At the front part of this surface is a small rounded eminence for the origin of one head of the

flexor digitorum superficialis muscle Flexor digitorum superficialis (''flexor digitorum sublimis'') is an extrinsic flexor muscle of the fingers at the proximal interphalangeal joints. It is in the anterior compartment of the forearm. It is sometimes considered to be the deepest pa ...

; behind the eminence is a depression for part of the origin of the flexor digitorum profundus muscle; descending from the eminence is a ridge which gives origin to one head of the pronator teres muscle. Frequently, the

flexor pollicis longus muscle The flexor pollicis longus (; FPL, Latin ''flexor'', bender; ''pollicis'', of the thumb; ''longus'', long) is a muscle in the forearm and hand that flexes the thumb. It lies in the same plane as the flexor digitorum profundus. This muscle is uniqu ...

arises from the lower part of the coronoid process by a rounded bundle of muscular fibers.

Function

The coronoid process stabilises the

elbow The elbow is the region between the arm and the forearm that surrounds the elbow joint. The elbow includes prominent landmarks such as the olecranon, the cubital fossa (also called the chelidon, or the elbow pit), and the lateral and the me ...

joint and prevents hyperflexion.

Clinical significance

The coronoid process can be fractured from its anteromedial facet.

Additional images

File:Gray213.png, Bones of left forearm. Anterior aspect. File:Elbow joint - deep dissection (anterior view, human cadaver).jpg, Elbow joint. Deep dissection. Anterior view. File:Slide2xzxzxz.JPG, Elbow joint. Deep dissection. Anterior view.

References

External links

* , *
X-ray at uams.edu
{{Authority control Ulna