Thenar muscles (for the thumb) :
superficial head
Trapezoid & capitate (deep head)
SEATHS
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 :
- 1st canal - Abductor pollicis longus & + Extensor pollicis brevis
- 2nd - Extensor carpi radiales brevis
- 3rd - Extensor pollicis longus &
- 4th - Extensor digitorum & + Extensor indicis
- 5th - Extensor digiti minimi
- 6th - Extensor carpi ulnaris
Carpal tunnel :
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. 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. 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. 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. Dorsal Carpal Sheath: It surrounds the extensor tendons of the wrist and hand as they traverse the dorsal aspect of the wrist.
- 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. Extensor Pollicis Longus Sheath: It surrounds the tendon of the extensor pollicis longus muscle as it crosses the wrist and extends into the thumb.