The hand skeleton

Made of 27 bones divided into three groups.

 

Three parts:
- The CARPUS corresponds to the wrist.
- The METACARPUS corresponds to the hand.
- The PHALANGES correspond to the fingers.

In more one notes the presence of the SESAMOÏDES: constant on the level of the métacarpo-phalangeal articulations of the inch, inconstant for the other fingers.

The whole of the bones form a concave arch into palmar.

THE CARPUS

It answers in proximal the radius and the radio-ulnar articular disc and into distal the métacarpiens.
It is made of eight small bones divided into two lines, a proximale, distal. These bones form a gutter very strongly concave into palmar the furrow carpien. The rétinaculum of flexor transforms the gutter into channel: CHANNEL CARPIEN. this rétinaculum is fixed on the tuber of the scaphoïde and the trapezoid into side on the pea-shaped one and the hamulus of the hamatum in médial.


1) FIRST LINE (PROXIMALE)

Of side with médial it is made of 4 small bones of form cuboïde having six faces to describe:
THE SCAPHOIDE
The LUNATUM (Semi lunar)
The TRIQUETRUM (Pyramidal)
THE PEA-SHAPED ONE

-> THE SCAPHOÏDE:

the side bone.
3 Faces articulaires cartilagineuses.
3 nonarticular Faces, the ventral face presents the tuber of the scaphoïde a side face and a dorsal face.
It is frequently fractured at the time of traumatism of the carpus, its vascularization is carried out the distal one with proximal, the consolidation of this fracture is long, frequently risk of pseudarthrose.

-> THE LUNATUM:
in the shape of crescent with caudal concavity, the center of the first line.
4 articular Faces
2 nonarticular Faces, dorsal face, ventral face.
(Also vascular pathology; necrose lunatum).

-> THE TRIQUETRUM:
bone médial of the first line.
4 articular Faces
2 nonarticular Faces the dorsal face: present a transverse projection, the peak of the triquetrum, the ventral face presents an articular facet for the pea-shaped one (ellipsoid).

-> THE PEA-SHAPED ONE:
smallest of the bones of the carpus (also of the first line), located into ventral of the triquétrum of ovoid form, at its dorsal face a socket presents.

2) THE SECOND LINE (DISTAL)

Of side with médial:

THE TRAPEZOID
THE TRAPEZOIDAL ONE
The CAPITATUM (Large bone)
The HAMATUM (hooked Os)


-> THE TRAPEZOID:
side bone of the second line
- 3 nonarticular Faces, the ventral face presents the tuber of the trapezoid.
- 3 articular Faces, the distal face is articulated with the base of the first and second métacarpien (articulation with reciprocal fitment).

-> THE TRAPEZOIDAL ONE:
the smallest bone of the second line, the most stable bone of the carpus.
- 4 articular Faces.
- 2 nonarticular Faces, the distal face is articulated with the base of the second métacarpien.

-> THE CAPITATUM:
the bulkiest bone of the carpus, central pivot of the wrist, centers carpus; on this bone the majority of the ligaments of the wrist are fixed.
It is formed: d'une TÊTE, d'un COL, d'un CORPS.
- 4 articular Faces
- 2 nonarticular Faces, the ventral face presents a tuber: ventral central tuber. The distal face is articulated with the second, third and fourth métacarpien.

-> The HAMATUM:
bone médial of the second line of the carpus, in the shape of pyramid;
- 3 articular Faces
- 3 nonarticular Faces, the ventral face presents a process bent in hook the hamulus, (this hook is in connection with the vessels and ulnar nerve); the distal face is articulated with the fourth and the fifth métacarpien.



II - THE METACARPUS

The métacarpiens are small long bones which constitute the palm of the hand, they are numbered of I with V of the inch to auricular (of side with médial).


1) GENERAL CHARACTERS:

The métacarpiens are long bones having a BODY, two EPIPHYSES: a proximale, BASES; distal, HEAD.

a) The Body: concave into palmar, triangular with the cut.
- 3 Faces:
* a dorsal face (smooth which answers the tendon bungee cord)
* two side faces (ventro side, ventromédiale) where stick the inter-osseous muscles.

- 3 Edges:
* a palmar edge -> concave
* two side edges, side and a médial -> little marked.

b) Epiphyses:

PROXIMAL: BASE métacarpien, cuboïde, articular. It has three articular surfaces: a power station which is articulated with the bone of the corresponding carpus, side a médiale which is articulated with the close métacarpien.

DISTAL: HEAD of the métacarpien (covered osseous of the fist) encrusted cartilage, elliptic (condyle), articular surface overflows into palmar.


2) PARTICULAR CHARACTERS:

MID-> is largest, cylindrical with the cut.
MII -> is longest.
MIII-> is the axis of the hand.
MIV -> is finest, more hail.
MV -> is shortest.



III - PHALANGES:
Skeleton of the fingers, long bone.

They are the last osseous parts of the thoracic member, it exists three phalanges by fingers, except for the inch (two).

- 14 phalanges in all.
- The phalanges are long bones, of proximal to distal:
Phalange proximale: Pi
Average phalange: PII
Distal phalange: PIII


- Inter-phalangeal articular surfaces are trochlées.
- The bases present a socket glénoïdale (for ellipsoidal pi and having two slopes for P II and P III.
- The heads present one trochlée for P I and P II.
- The diaphyses are in the shape of tile, semi cylindrical (two edges, two faces)
- There exists on the last phalange of the five fingers a surface which serves as sitted with the nail (head of P III), also pulp supports. Phalangeal bunch in the horseshoe shape.