What is the Wrist Joint?
The anatomical structure of the wrist joint is probably the most complex and intricate of the entire human body. The wrist consists of several bones and joints.
This complexity enables the hand to move in all directions as well as to perform various activities.
Caption: Wrist joint. The bones of the joint are eight and arranged in two rows, the proximal row and the distal row. The proximal row, starting from the thumb, consists of the following bones: 1) scaphoid, 2) lunate, 3) triquetrum, while the distal row consists of the: 4) trapezium, 5) trapezoid, 6) hamate, 7) pisiform. Centrally, they are in contact with the radius and the ulna, while peripherally with the metacarpal bones. Tendons and nerves pass through the dorsal surface of the wrist.
What does the wrist joint consist of?
A total of fifteen carpal bones make up the joint from the periphery of the forearm to the hand. The wrist consists of eight bones arranged in two rows.
The proximal range consists of:
- the scaphoid
- the lunate
- the triquetrum
and the peripheral series consists of the other five:
- the trapezium
- the trapezoid
- the capitate
- the hamate
- the pisiform
Caption: Tendons and nerves passing through the dorsal surface of the wrist.
This row comes in contact with the metacarpal bones, while the proximal line is connected to the forearm bones, the radius and the ulna.
Essentially, the wrist joint is made up of several small joints, thereby providing significant flexibility and functionality to the hand.
The articular cartilage, which is a white, glossy and particularly slippery structure, covers the bone surfaces in contact with each other, thus assisting in the smooth and painless function of the joint.
The joints are made of soft but very durable tissue, which connects the bones with each other giving them stability and strength.
The articular pouch encloses the joint like a glove and contains the synovial fluid, a substance with excellent lubricating properties.
One particular structure is the triangular cartilage located between the ulnar, the lunate and the triquetral bone.
It is a chondral construction and its rigidity is a prerequisite for the smooth operation of the joint.
Caption: Tendons and nerves on the palmar surface of the wrist.
Many tendons – flexors on the palmar surface extending to the dorsal surface, pass through the wrist and constitute the driving force of the joint and the hand.
All the upper extremity nerves intersect with the wrist; the ulnar, the median, and the radial nerve.
These nerves carry commands from the brain to the muscles, in order to move:
- the forearm
- the wrist joint
- the hand
- the fingers
and return information to the brain regarding sensitivity, pain and temperature.
Finally, the arteries and veins that provide blood supply to the hand.
The coronary artery passes through the palmar surface of the wrist near the thumb, while the ulnar artery closest to the little finger.
The two arteries will unite and create two arches in the palm of the hand, which are the sources of blood supply throughout the hand.
Caption: Magnetic resonance imaging of the wrist joint. The remarkable structure of the bones of the wrist can be distinguished, which contributes decisively to the smooth and special function of the hand.