ulna bone (ULNA)


I- Introduction :

The ulna shape with the radius of the two bones Lavant arm. C & rsquo; is & rsquo; s internal bones & rsquo; forearm. It is even, long. It s & rsquo; articulates 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 & rsquo; the bulkier 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 front of the & rsquo; s & rsquo ulna; inserts the deep flexor digitorum (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 & rsquo; insertion of the flexor nrofond finger overlaps the inner 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
  • muscle extensor of & rsquo; index.

Above these four inserts, there is a small ridge that defines the & rsquo; insertion anconeus (l & rsquo; one of the epicondyle 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 & rsquo; horizontal (the coronoid process) and & rsquo; other vertical (l & rsquo; olecranon). The whole forms a hook that fits the humeral trochlea. L & rsquo; olecranon process and the coronoid consist of two concave facets separated by a ridge, to meet the two convex cheeks of the humeral trochlea.

  • L & rsquo; 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 surface of the & rsquo; 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 ridge down the middle & rsquo; attachment of muscles flexor carpi ulnaris (inside) and extensor carpi ulnaris (outside).

B- lower epiphysis :

C & rsquo; is the ulnar head. It s & rsquo; only articulates with the ulnar side of the radius. It is covered with cartilage and is extended in a styloid process

Pr BELHOULA's course – Faculty of Constantine