Sections of forearm and hand

Transverse section of proximal third of hand, partially dissected

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Image #112-4
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Sections of forearm and hand
Transverse section of proximal third of hand, partially dissected
Interosseous and hypothenar muscles have been removed to a depth of 5 mm. on the proximal section to illustrate the interosseous and hypothenar fasciae and the various septa which extend to the metacarpal bones. The flexor tendons to the middle finger (15) have also been removed from the proximal section to display the synovial sheath which encloses them. The "mid-palmar space", a cleft-like region of delicate connective tissue deep to the flexor tendons and lumbrical muscles, has been spread open at 14. A single, dense, fibrous septum (2) extends from the palmar aponeurosis to the volar interosseous fascia lateral to the second lumbrical. This separates the flexor tendons and lumbrical of the index finger from the remaining tendons and lumbricals. The "mid-palmar space" is thus interrupted by this septum. A similar space, or cleft, lateral to this septum has been designated as the "thenar space". This cleft can be traced around the distal margin of the adductor pollicis to the area between the adductor and the first dorsal interosseous muscle. Other septa similar to the one described (2) appear more distally in the palm. These separate the remaining tendons and lumbricals from each other as they approach the fingers.
1 . Left pointer: Flexor digitorum superficialis (tendon) Right pointer: Lumbrical muscle I
2 . Fibrous septum between palmar aponeurosis and anterior interosseous fascia (see text above)
3 . Palmar aponeurosis
4 . Flexor digitorum superficialis (tendons)
5 . Opponens digiti minimi muscle
6 . Abductor digiti minimi muscle
7 . Metacarpal V
8 . Common extensor digitorum muscle (tendons covered by dorsal fascial of the hand)
9 . Dorsal subaponeurotic cleft
10 . Hypothenar fascia
11 . Dorsal interosseous fascia
12 . Anterior interosseous fascia (note septa extending from this layer to metacarpals)
13 . Anterior common digital artery and nerve
14 . Mid-palmar space (cleft), exposed by anterior retraction of lumbrical muscle and synovial sheath
15 . Sheath of common tendon of flexor muscles (tendons removed)
16 . Superficial fascia (traversed by vertical fibrous septa between dermis and palmar aponeurosis)
17 . Adductor fascia
18 . Adductor pollicis muscle
19 . Flexor pollicis longus muscle (within synovial sheath)
20 . Phalanx I
21 . Extensor pollicis longus muscle (tendon)
22 . Flexor digitorum profundus muscle (tendons)
23 . Dorsal interosseous muscles
24 . Anterior interosseous muscles
25 . Sesamoid bone
26 . Flexor pollicis brevis muscle (insertion)