**18. Functional anatomy of the wrist joint**

The bony wrist joint (**Figure 8**) is made up of the articulation of the distal radius and ulna bones with the carpal bones. The carpal bones are arranged in two rows, the 1st or proximal row and the second or distal row.

The proximal row comprises of the scaphoid, lunate triquetrum and trapezoid bones.

The second carpal row consists of the pisiform, trapezium capitate and hamate bones.

The first row of bones is a more mobile articulation in comparison to the second row which acts as one. The scaphoid communicates through both rows.

There are 3 axes of motion at the wrist joint; Flexion/Extension; Ulnar/Radial deviation; Pronation/Supination (see **Figure 2**). According to the "link" concept of wrist biomechanics a chain of communication exists between the radius, lunate and capitate bones, with the head of the capitate bone acting as the centre of rotation. The proximal row in the form of the lunate can act as an intercalated unit as it has no direct tendon attachment. The distal row of carpal bones act as a complete unit. The scaphoid bridges both rows. When the wrist is in ulnar deviation the scaphoid is pushed into extension, and radial deviation pushes it into flexion.

The bones are held together in a lattice of extrinsic and intrinsic wrist ligaments.

The extensor tendons at the level of the wrist are divided into six extensor compartments (**Figure 9**) that are designated by Roman numerals from lateral to medial:

i.Extensor pollicis brevis, abductor pollicis longus.

ii.Extensor carpi radialis longus, extensor carpi radialis brevis.

**Figure 8.** *Bony anatomy of the wrist, showing the 2 carpal rows.*

*Leading Wrist Injuries in a Golfing Population. Golf Swing Biomechanics a Significant Cause… DOI: http://dx.doi.org/10.5772/intechopen.96979*

#### **Figure 9.**

*The 6 extensor compartment of the wrist joint.*


The 6th compartment is the most compromised during the golf swing. The first extensor compartment is most affected in skiing, fishing and racket sports with a common occurrence of De Quervain's Tenosynovitis.

The flexor tendons of the wrist are divided into two main structures: 1) the flexor digitorum profundus (FDP) and the flexor digitorum superficialis (FDS) tendons.

FDP tendons help bend the index, middle, ring, and small fingers at the fingertip joint. FDS tendons help flexes the index, middle, ring, and small fingers at the middle finger joint. 9 of these flexor tendons travel into the wrist through the carpal tunnel. Each of the flexor tendons perform an important function in gripping the golf club in a consistent fashion to allow a natural swing of the club.
