Carpus

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Carpus

Vertical section through the articulations at the wrist, showing the synovial cavities.

Bones of the left hand. Palmar surface.
Gray's	subject #54 221
MeSH	Carpal+Bones

This article is about Carpal bones. In Greek mythology, Carpus (Greek: Karpos, "fruit") was a son of Chloris and Zephyrus.

In tetrapods, the carpus is the cluster of bones in the hand between the radius and ulna and the metacarpus. The bones of the carpus do not belong to individual fingers, whereas those of the metacarpus do. The joint between the radius and ulna and the carpus is called the wrist. The corresponding part of the foot is the tarsus.

The carpal bones have evolved differently in different animals (for example in some macropods, the scaphoid and lunar bones are fused into the scapholunar bone)[1].

1 The Carpus (Ossa Carpi)
2 Common characteristics of the carpal bones
3 Articulations
4 See also
5 External links

[edit] The Carpus (Ossa Carpi)

The eight carpal bones form two rows (some are now renamed from Latin).

[edit] Proximal

Those of the proximal row, from the radial to the ulnar side, are:
- Scaphoid bone with the lunate, articulates with the radius of the arm
- Lunate bone articulates with the radius and the capitate
- Triquetral bone on the ulnar side of the hand, but does not articulate with the ulna.
- Pisiform bone a sesamoid bone

[edit] Distal

Those of the distal row, in the same order, are:
- Trapezium (bone) articulates with the metacarpal of the thumb.
- Trapezoid articulates with the 2nd metacarpal.
- Capitate articulates with the metacarpal of the middle finger.
- Hamate articulates with the metacarpals of the 4th and 5th fingers. It has a projection called a hook.

[edit] Mnemonics

Mnemonics to remember these:

Some lovers try positions / that they can't handle.
Sally left the party / to take Cathy home.
Students Like The Professor To Teach Complex Hypotheses
She Likes Taking Prostitutes To The Calley Hotel
She Looks Too Pretty Try To Catch Her
Stop Letting Those People Touch The Cadaver's Hands

A Hindi version which is quite funny and hence popular among students in India, is:

Sneh Lata Tinde Paka Tere Tinde Catchey Hain

which can be roughly translated as an exhortation to a woman called Sneh Lata, asking her to properly cook a vegetable!

[edit] Common characteristics of the carpal bones

BONES OF HAND
Proximal: A=Scaphoid, B=Lunate, C=Triquetral, D=Pisiform
Distal: E=Trapezium, F=Trapezoid, G=Capitate, H=Hamate

Each bone (excepting the pisiform) presents six surfaces.

Of these the palmar or anterior and the dorsal or posterior surfaces are rough, for ligamentous attachment; the dorsal surfaces being the broader, except in the lunate.

The superior or proximal, and inferior or distal surfaces are articular, the superior generally convex, the inferior concave; the medial and lateral surfaces are also articular where they are in contact with contiguous bones, otherwise they are rough and tuberculated.

The structure in all is similar: cancellous tissue enclosed in a layer of compact bone.

[edit] Articulations

In humans:

scaphoid articulates with 5 bones – radius, lunate, capitate, trapezoid, trapezium
lunate articulates with 5 bones - radius, scaphoid, capitate, hamate, triquetral
triquetral articulates with 3 bones – pisiform, hamate, lunate
pisiform articulates only with triquetral, sitting on top of it
trapezium articulates with 4? bones – thumb metacarpal, scaphoid, trapezoid, index finger metacarpal
trapezoid articulates with 4 bones – scaphoid, capitate, metacarpal of index finger, trapezium
capitate articulates with 7 bones – hamate, lunar, scaphoid, trapezoid and index, third and fouth metacarpals
hamate articulates with 5 bones – triquetral, lunate, capitate, and fourth and fifth metacarpals