Atlas of Anatomy

21 Wrist & Hand

Bones of the Wrist & Hand

Fig. 21.1   Dorsal view
Right hand.

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Fig. 21.2   Palmar view
Right hand.

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Fig. 21.3   Radiograph of the wrist
Anteroposterior view of left limb.

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Scaphoid Fractures
Scaphoid fractures are the most common carpal bone fractures, generally occurring at the narrowed waist between the proximal and distal poles (A, right scaphoid). Because blood supply to the scaphoid is transmitted via the distal segment, fractures at the waist can compromise the supply to the proximal segment, often resulting in nonunion and avascular necrosis

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Joints of the Wrist & Hand

Fig. 21.4   Joints of the wrist and hand

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Fig. 21.5   Wrist and hand: Coronal section
Right hand.

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Ligaments of the Wrist & Hand

Fig. 21.6   Ligaments of the hand
Right hand.

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Fig. 21.7   Ligaments of the carpal tunnel
Right hand, anterior view.

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Fig. 21.8   Carpal tunnel
Transverse section. The contents of the carpal tunnel are discussed on p. 342. See p. 343 for the ulnar tunnel and palmar carpal ligment.

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Ligaments of the Fingers

Fig. 21.9   Ligaments of the fingers: Lateral view
Right middle finger. The outer fibrous layer of the tendon sheaths (stratum fibrosum) is strengthened by the annular and cruciform ligaments, which also bind the sheaths to the palmar surface of the phalanx and prevent palmar deviation of the sheaths during flexion.

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Fig. 21.10   Anterior view
Right middle finger, palmar view.

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Fig. 21.11   Third metacarpal: Transverse section
Proximal view.

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Fig. 21.12   Fingertip: Longitudinal section
The palmar articular surfaces of the phalanges are enlarged proximally at the joints by the palmar ligament. This fibrocartilaginous plate, also known as the volar plate, forms the floor of the digital tendon sheaths.

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Muscles of the Hand: Superficial & Middle Layers

Fig. 21.13   Intrinsic muscles of the hand: Superficial and middle layers
Right hand, palmar surface.

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Dupuytren's contracture
Gradual atrophy of the palmar aponeurosis leads to progressive shortening of the palmar fascia, chiefly affecting the 4th and 5th digits. Over a period of years, the contracture may become so severe that the fingers assume a flexed position (with fingertips touching the palms), severely compromising the grasping ability of the hand. The causes of Dupuytren's contracture are poorly understood, but it is a relatively common condition, most prevalent in men over 40 and associated with chronic liver disease (i.e., cirrhosis). Treatment generally consists of complete surgical removal of the palmar aponeurosis.

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Tendon sheath communication
The digital tendon sheath of the thumb is continuous with the carpal tendon sheath of the pollicis longus. The remaining fingers show variable communication with the carpal tendon sheaths (A is the most common variation). Infections within the tendon sheaths from puncture wounds of the fingers can track proximally to communicating spaces of the hand.

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Muscles of the Hand: Middle & Deep Layers

Fig. 21.14   Intrinsic muscles: Middle and deep layers
Right hand, palmar surface.

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Fig. 21.15   Origins and insertions
Right hand. Muscle origins shown in red, insertions in blue.

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Dorsum of the Hand

Fig. 21.16   Extensor retinaculum and dorsal carpal tendon sheaths
Right hand, posterior (dorsal) view.

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Fig. 21.17   Muscles and tendons of the dorsum
Right hand.

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Fig. 21.18   Dorsal digital expansion
Right hand, middle finger. The dorsal digital expansion permits the long digital flexors and the short muscles of the hand to act on all three finger joints.

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Muscle Facts (I)

images The intrinsic muscles of the hand are divided into three groups: the thenar, hypothenar, and metacarpal muscles (see p. 314). The thenar muscles are responsible for movement of the thumb, while the hypothenar muscles move the 5th digit.

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Fig. 21.19   Thenar and hypothenar muscles
Right hand, palmar (anterior) view.

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Fig. 21.20   Thenar and hypothenar muscles
Right hand, palmar (anterior) view.

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Muscle Facts (II)

images The metacarpal muscles of the hand consist of the lumbricals and interossei. They are responsible for the movement of the digits (with the hypothenars, which act on the 5th digit).

Fig. 21.21   Lumbricals
Right hand, palmar view.

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Fig. 21.22   Dorsal interossei
Right hand, palmar view.

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Fig. 21.23   Palmar interossei
Right hand, palmar view.

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Fig. 21.24   Metacarpal muscles
Right hand, palmar (anterior) view.

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