{"id":4127,"date":"2021-01-30T00:11:29","date_gmt":"2021-01-29T23:11:29","guid":{"rendered":"https:\/\/meddists.com\/learn\/pre-clinical\/anatomy\/upper-limb\/hand\/carpal-tunnel-and-structures-at-the-wrist\/"},"modified":"2021-03-15T23:12:16","modified_gmt":"2021-03-15T22:12:16","slug":"carpal-tunnel-and-structures-at-the-wrist","status":"publish","type":"page","link":"https:\/\/meddists.com\/learn\/pre-clinical\/anatomy\/upper-limb\/hand\/carpal-tunnel-and-structures-at-the-wrist\/","title":{"rendered":"Carpal tunnel and structures at the wrist"},"content":{"rendered":"\n
The carpal tunnel is a passage in the wrist formed by the carpal bones and the overlying structures, allowing structures to pass from the forearm to the hand and back.<\/div><\/p>\n\n\n\n
Formed by four carpal bones<\/strong> and the flexor retinaculum<\/strong>, the carpal tunnel forms as a deep arch on the anterior surface of the wrist.<\/p>\n\n\n\n
Medially, it is formed by the pisiform<\/strong> and hook of the hamate bones<\/strong>, while laterally, it is formed by the tubercles of the scaphoid and trapezium bones<\/strong>.<\/li>
Both sides of the carpal arch are connected by the flexor retinaculum<\/strong>, a thick layer of connective tissue, forming the tunnel.<\/li>
It serves as a pathway for:
The tendons of the flexor digitorum profundus muscles.<\/li>
The tendons of the flexor digitorum superficialis muscles.<\/li>
The tendon of the flexor pollicis longus muscle.<\/li>
The median nerve.<\/li><\/ul><\/li>
These structures are held together by synovial sheaths<\/strong>, one for the flexor digitorum muscles and one for the flexor pollicis longus muscle.<\/li>
Other related structures pass into the hand by having a close relation with the carpal tunnel, but without being part of it:
The tendon of the flexor carpi radialis muscle has its own synovial sheath placed laterally in the flexor retinaculum.<\/li>
Anterior to the flexor retinaculum, the ulnar artery and ulnar nerve pass in their own synovial sheath, while the tendon of the palmaris longus muscle passes without one.<\/li>
Dorsally and laterally, the radial artery passes adjacent to the surface of the scaphoid bone.<\/li><\/ul><\/li>
The tendons of the extensor muscles pass through the extensor retinaculum<\/strong>, in which these are organized into six different compartments with their own synovial sheaths:
Posteriorly, the tendons of the extensor digitorum and extensor indicis muscles.<\/li>
Medially, the tendons of the extensor carpi ulnaris and extensor digit minimi muscles are separated into two compartments.<\/li>
Laterally, three compartments separate the tendons of the abductor pollicis longus and extensor pollicis brevis muscles, the tendons of the extensor carpi radialis longus and extensor carpi radialis brevis muscles, and the tendon of the extensor pollicis longus muscle.<\/li><\/ul><\/li><\/ul>\n\n\n\n
Palmar aponeurosis.<\/strong><\/p>\n\n\n\n
Resulting from the thickening of the deep fascia<\/strong> that covers the palm, the palmar aponeurosis<\/strong> is attached distally to the skin.<\/p>\n\n\n\n
Placing itself in a triangular shape, its apex is attached to the flexor retinaculum<\/strong> (when the tendon of the palmaris longus muscle<\/strong> is not present).<\/li>
Its fibers extend to each finger<\/strong>, with a lesser extent to the thumb. These fibers are interconnected by transverse fibers<\/strong>.<\/li>
Deep relations include vessels, nerves, and tendons of long flexor muscles.<\/li><\/ul>\n\n\n\n
Palmaris brevis muscle.<\/strong><\/p>\n\n\n\n
The palmaris brevis muscle<\/strong> is a small, quadrangular-shaped, medial, subcutaneous muscle of the palm of the hand.<\/p>\n\n\n\n
Originating from the flexor retinaculum<\/strong> and palmar aponeurosis<\/strong>, it inserts into the medial skin of the hand<\/strong>.<\/li>
Superficial to the hypothenar muscles<\/strong>, ulnar artery<\/strong>, and superficial branch of the ulnar nerve<\/strong>, which innervates it.<\/li>
It deepens the cup of the palm<\/strong> and improves the grip<\/strong>.<\/li><\/ul>\n\n\n\n
Anatomical snuffbox.<\/strong><\/p>\n\n\n\n
The anatomical snuffbox is a triangular depression found at the posterolateral side of the wrist <\/strong>and the first metacarpal<\/strong> (of the thumb), a triangular depression known as the anatomical snuffbox<\/strong> can be located.<\/p>\n\n\n\n
The tendons of the abductor pollicis longus<\/strong> and extensor pollicis brevis muscles<\/strong> form the lateral border<\/strong>.<\/li>
The tendon of the extensor pollicis longus muscle<\/strong> forms the medial border<\/strong>.<\/li>
The base<\/strong> is formed by the wrist<\/strong>, while the apex<\/strong> directs into the thumb<\/strong>.<\/li>
The scaphoid<\/strong> and trapezium bones<\/strong>, the tendons of the extensor carpi radialis longus<\/strong> and extensor carpi radialis brevis muscles<\/strong> form the floor.<\/li>
It has relations with the radial artery<\/strong>, radial nerve<\/strong>, and cephalic vein<\/strong>.<\/li><\/ul>\n\n\n\nAnatomical snuffbox (in red)<\/strong><\/figcaption><\/figure>\n\n\n\n
Fibrous digital sheaths.<\/strong><\/p>\n\n\n\n
At their entrance into the hand, each tendon of the flexor digitorum superficialis<\/strong> and profundus muscles<\/strong> extend into each finger with their own fibrous sheath<\/strong>. These hold the tendons to the bones, while passing over the metacarpophalangeal<\/strong> and interphalangeal joints<\/strong>.<\/p>\n\n\n\n
Extensor hoods.<\/strong><\/p>\n\n\n\n
At their passage onto the dorsal surface of the fingers, the tendons of the extensor digitorum<\/strong> and extensor pollicis longus muscles<\/strong> are held to the bones due to its triangular expansions into extensor hoods<\/strong>. These are joined by the tendons of the extensor digiti minimi<\/strong>, extensor indicis<\/strong>, and extensor pollicis brevis muscles<\/strong>. The hoods are attached to the metacarpophalangeal joint<\/strong>, phalanxes<\/strong>, intrinsic muscles<\/strong>, and metacarpal ligaments<\/strong>.<\/p>\n\n\n\n
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