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1.3.5 Pulley-like structures and ligaments at the wrist

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(2.22)

We’ve looked at the bones and joints of the hand, and at the movements they’re capable of. Before we move on to look at the muscles which move the fingers and thumb, and the tendons by which they act, there are a number of important pulleys and sliding strutures that we need to understand. These structures guide the direction of pull of the tendons as they cross the wrist joint, and pass along the fingers.

We’ll look first at the two big pulleys at the wrist, the flexor retinaculum, and the extensor retinaculum.

Here’s the flexor retinaculum. It’s a tough, unyielding strap of fibrous tissue. The flexor retinaculum is the structure that forms the roof of the carpal tunnel. It’s attached on the radial side to the scaphoid and the trapezium, and on the ulnar side to the pisiform bone, and the hook of the hamate. As we’ll see, the median nerve, and all the flexor tendons to the fingers and thumb go through the carpal tunnel.

The flexor retinaculum branches off in two places, here and here, to enclose two small, separate tunnels. This one, on the radial side, encloses the tendon of flexor carpi radialis. This one, superficial and on the ulnar side, encloses the ulnar artery and nerve.

We’ll be returning to the flexor retinaculum later, to look at some important structures that arise from it: the palmar aponeurosis, and some of the thenar and hypothenar muscles.

Let’s go round now to the dorsal aspect of the wrist, to see the other big pulley, the extensor retinaculum. It runs obliquely, from this ridge on the radius, to the ulnar styloid, the triquetrum, and the hamate.

The extensor retinaculum has a number of deep extensions which are attached to the underlying radius. These divide the space under ...

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(2.22)

We’ve looked at the bones and joints of the hand, and at the movements they’re capable of. Before we move on to look at the muscles which move the fingers and thumb, and the tendons by which they act, there are a number of important pulleys and sliding strutures that we need to understand. These structures guide the direction of pull of the tendons as they cross the wrist joint, and pass along the fingers.

We’ll look first at the two big pulleys at the wrist, the flexor retinaculum, and the extensor retinaculum.

Here’s the flexor retinaculum. It’s a tough, unyielding strap of fibrous tissue. The flexor retinaculum is the structure that forms the roof of the carpal tunnel. It’s attached on the radial side to the scaphoid and the trapezium, and on the ulnar side to the pisiform bone, and the hook of the hamate. As we’ll see, the median nerve, and all the flexor tendons to the fingers and thumb go through the carpal tunnel.

The flexor retinaculum branches off in two places, here and here, to enclose two small, separate tunnels. This one, on the radial side, encloses the tendon of flexor carpi radialis. This one, superficial and on the ulnar side, encloses the ulnar artery and nerve.

We’ll be returning to the flexor retinaculum later, to look at some important structures that arise from it: the palmar aponeurosis, and some of the thenar and hypothenar muscles.

Let’s go round now to the dorsal aspect of the wrist, to see the other big pulley, the extensor retinaculum. It runs obliquely, from this ridge on the radius, to the ulnar styloid, the triquetrum, and the hamate.

The extensor retinaculum has a number of deep extensions which are attached to the underlying radius. These divide the space under the retinaculum into several small, separate tunnels. All three wrist extensors, and all the extensor tendons to the fingers and thumb, pass under the extensor retinaculum.

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