#boneoftheweek

Image Source: Japan Life Science Databases(LSDB), Anatomography. Vomer bone from Anatomography maintained by Life Science Databases(LSDB). Wikimedia Commons.

Image Source: Anatomography. Ulna.Wikimedia Commons.

The Ulna is the longest and thinnest of the two long bones located in the forearm. At the elbow, the ulna articulates with the trochlea of the humerus and with the radial head. Distally (at the wrist) the ulnar notch of the radius articulates with the ulna. These articulations allow the ulna to provide freer rotation of the hand and radius.

Some notable landmarks of the ulna include: 

(From Elbow (Proximal) to Wrist (Distal). 

Olecranon Process: Located posteriorly and inserts into the olecranon fossa of the humerus. It is the most proximal and larger end of the bone. The triceps brachii muscle (the primary extensor of the forearm) inserts on the tuberosity of this process. (Image A #1, Image B #6)

Coronoid Process: The process that fits into the coronoid fossa of the humerus. (Image A #3)

Trochlear notch: Also known as semilunar, articulates with the trochlear surface of the distal humerus (at the elbow). (Image A #2) 

Radial Notch: Where the head of the radius sits located on the lateral margin of the coronoid process. (Image A #4) 

Interosseus Crest: (Or border) is the sharpest border of the ulna which is located opposite to the radius. (Image B, border left of #7)

Extensor Carpi Ulanris Groove: Here rests the tendon of the extensor carpi ulnaris muscle. (Image B, groove to the right of #11)

Styloid Process: On the posterior (back part) of the ulnar head is the most distal projection of the bone. It is sharp, and here the ulnar collateral ligament of the wrist attaches. (Image A #7, Image B #11)

Image A: (Below)

Source: Originaly by Henry Vandyke Carter (1831–1897) vectorized and reworked by user: Jppialasse. Ulna et Radius. Vue de face avec les éléments osseux remarquables. Wikimedia Commons. 

Image B: (Below)

Source: Originaly by Henry Vandyke Carter (1831–1897) vectorized and reworked by user: Jppialasse. Ulna et Radius. Vue de face avec les éléments osseux remarquables. Wikimedia Commons.

Bonus: The nasal bone articulates with four other bones, on the cranium; the frontal and ethmoid, and on the face; the opposite nasal and the maxilla.

Pop Quiz: What does the term “Oblong” mean?