Bones and Muscles · 47. Muscles and synovial sheaths of hand.

Thenar muscles (for the thumb):

superficial head

Trapezoid & capitate (deep head)

Metacarpal group:

Lumbricals muscles

SYNOVIAL

• When the antebrachial fascia reaches the wrist ,it form a thick band called flexor retinaculum and an extensor retinaculum .
• these bands are crucial because they organize the blood flow and the tendons of the muscles.
• Other fascia of the hand:
• Palmar Aponeurosis
• Superficial palmar fascia
• u dorsal fascia.
• The Extensor Retinaculum forms 6 canals on the back of the wrist for the tendons of extensor muscles to go through:

1. 1st canal - Abductor pollicis longus & + Extensor pollicis brevis
2. 2nd - Extensor carpi radiales brevis
3. 3rd - Extensor pollicis longus &
4. 4th - Extensor digitorum + Extensor indicis
5. 5th - Extensor digiti minimi
6. 6th - Extensor carpi ulnaris

Carpal tunnel:

SEATHS

• The Flexor retinaculum forms canals
• Carpal Canal contains:
• 4 Tendons of flexor digitorum profundus
• + 4 Tendons of flexor digitorum superficialis
• + Flexor pollicis longus
• + Median nerve
• + Flexor carpi radialis
• Ulnar canal contains:
• Ulnar n. + 2 ulnar veins
• + ulnar artery.
• Each canal forms a sheath around the tendons to protect them from damage.
• Synovial sheaths are specialized structures lined with synovial fluid, which reduce friction when tendons passes between 2 surfaces

1. 1. Flexor Retinaculum Sheath: This sheath surrounds the flexor tendons of the fingers and the median nerve as they pass through the carpal tunnel in the wrist.
2. 2. Digital Synovial Sheaths: These sheaths envelop the flexor tendons of the fingers as they pass through the palm and into the fingers. There are five digital synovial sheaths, one for each finger.
3. 3. Palmar Carpal Sheath: This sheath covers the tendons of the flexor carpi radialis and flexor carpi ulnaris muscles as they pass through the wrist.
4. 4. Dorsal Carpal Sheath: It surrounds the extensor tendons of the wrist and hand as they traverse the dorsal aspect of the wrist.
5. 5. Extensor Digitorum Communis Sheath: This sheath encloses the tendons of the extensor digitorum communis muscle as they pass through the wrist and into the fingers.
6. 6. Extensor Pollicis Longus Sheath: It surrounds the tendon of the extensor pollicis longus muscle as it crosses the radius and extends into the thumb.