ulna bone (ULNA)


I- Introduction :

The ulna shape with the radius of the two bones Lavant arm. C’is’internal bone’forearm. It is even, long. it s’hinges up with:
The trochlea of ​​the humerus The periphery of the radial head is hinged at the bottom with :
The carpal condyle.
The sigmoid notch of the radius.

Placing :

  • Up : l’larger end
  • Forward : large joint recess of said end
  • Outside : Early articular indentation thereof

II- descriptive anatomy :

The ulna has to describe :
* A body or shaft
* Both ends or epiphyses : proximal (higher) and distal (lower)

1- Body or shaft :

three sides : previous, posterior and medial.
three edges : prior, posterior and lateral

* the faces

front face :

Its caliber is reduced from top to bottom. On most of the anterior surface of the’ulna s’inserts deep flexor muscle of fingers (the 3/4 higher) and the remaining portion (1/4 inferior) fits the square pronator muscle.

posterior :

Same general aspects to the shaft, long double curvature. L’insertion of the flexor muscle n deep of the fingers overflows on the internal edge, then a little on the posterior face- intemal. On the posterior external, four successive insertions from top to bottom :

  • long abductor muscle of the thumb
  • muscle extensor thumb
  • muscle extensor thumb
  • clean extensor muscle’index.

Above these four inserts, there is a small ridge which delimits the’insertion du muscle anconé (l’one of the epicondylar muscles).

medial :

Gives insertion to the muscle flexor (deep flexor digitorum)

* Edges :

front edge :

Gives insertion to the muscle flexor (deep flexor digitorum)

posterior margin :

Gives insertion to the flexor and extensor carpi ulnaris (ulnar anterior and posterior ulnar)

lateral edge :

Give insertion Supinator (court supinateur)

2- epiphyseal :

A- upper epiphysis :

It consists of two extensions, l’a horizontal (the coronoid process) and l’other vertical (l’olecranon). The whole forms a hook that fits the humeral trochlea. L’olecranon and the coronoid process consist of two concave facets separated by a ridge, to meet the two convex cheeks of the humeral trochlea.

  • L’ulna has on the outer side of the coronoid process, a radial facet which receives the circumference of the radial head.

-On the front of the coronoid process, fits the brachialis, and the pronator teres muscles and superficial finger flexor.

  • The posterior side of the’olecranon is marked by two oblique ridges, that coalesce to form the ulnar crest. Along these ridges down the insertions of muscles triceps. Along the middle ridge descends l’carpal ulnar flexor insertion (inside) and extensor carpi ulnaris (outside).

B- lower epiphysis :

C’is the ulnar head. it s’articulates only with the ulnar facet of the radius. It is covered with cartilage and is extended in a styloid process

Pr BELHOULA's course – Faculty of Constantine