The hand is part of the upper limb below the forearm and wrist. In the supinated anatomical position, the palm is facing anteriorly and the dorsum posteriorly.
The bones of the hand are:
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carpals (8)
metacarpals (5)
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phalanges (13)
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proximal and distal phalanges
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other digits
proximal, middle and distal phalanges
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On this page:
Terminology
As the thumb is structurally different to the other digits of the hand, with different movements and musculature, there is debate as to whether the thumb is considered a finger 2. It can therefore confusing to refer to the fingers by number - is the "first finger" the thumb or the first of the four other digits? For this reason it is advisable to refer to the digits by names given to them rather than by number. From the radial to the ulnar aspect of the hand, they are named as follows:
thumb
index finger
middle finger or long finger
ring finger
little finger
In the standard anatomical position, the hand is flat and supinated with the fingers spread. This positions the thumb at the lateral aspect of the hand and the little finger at the medial aspect of the hand. It is often easier to use radial and ulnar to refer to the lateral and medial aspects of structures in the hand, as these may be more intuitive without having to remember the anatomical position.
Joints
Hand movement is complex and occurs across many joints, including those involved in wrist flexion.
Muscles
Muscles of the hand can be divided into:
extrinsic muscles whose tendons arise from muscle bellies within the forearm, and
intrinsic muscles (mnemonic) whose muscle bellies are located within the hand
Compartments
Fascial layers subdivide the underlying musculature into functional compartments; clinical relevance becomes manifest with pathologic increases in pressure resulting in ischaemia and/or necrosis to the structures within the myofascial confines such as muscle and peripheral nerves.
The compartments are typically identified as the following 3:
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thenar compartment
contains abductor pollicis brevis, opponens pollicis, flexor pollicis brevis, ulnar nerve branches
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hypothenar compartment
opponens digiti minimi, flexor digiti minimi, abductor digiti minimi
adductor pollicis compartment
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interossei compartments
encompasses 3 palmar and 4 dorsal compartments
no musculature, contains ulnar nerve branches
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central or mid-palmar compartment
anatomically continuous with the carpal tunnel
contains the second through fourth lumbrical muscles