REIDER PART 1
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Without the human hand, the most rcfincd creations of the human mind would be mere theoretical concepts. The hand is the focal point of human beings’ interactions with the eiwironment; it is the instrument used to deliver a knockout punch or to perform brain surgery. The hand is an organ of such complexity that many devote their lives to studying it and curing its ills.

The varied functions of the hand include grasping, pinching, and acting as a hook or paperweight. About 45% of the work of the hand utilizes grasp, a power func-tion that reąuires coordinated action of both the intrinsic hand muscles and the extrinsic thumb and finger flexors. Variations of the grasp mechanism allow a person to make a tight fist or to securely hołd an object such as a bali or glass (Fig. 4-M). Another 45% of hand function utilizes pinch. Varieties of pinch include side pirtch (key pinch), between the tip of the thumb and the side of the index finger (Fig. 4-1B); tip pinch, between the tip of the rotated thumb and the tip of another finger (Fig. 4-1C); and chuck pinch, which requires opposition of the thumb to form a triangular chuck with the tips of the long and ringfingers (Fig. 4-1D). About 5% of the hands activitics requirc functioning as a hook. This morę primi-tive function allows the curved fingers to span handlcs or support thin objects (Fig. 4-1E). In the remaining 5% of tasks, the hand functions as a paperweight (Fig. 4-1F). This most primitive of hand functions does not require the intrinsic strength or fine manipulative abilities ncccs-sary for morę delicate tasks. Chronić pain prevents any useful task.

The hand functions well because it is suspended at the end of the arm. The shoulder and elbow serve to position the hand in space, allowing it to perform the precise functions required. Before commencing a detailed examination of the hand and the wrist, the examiner must perform a generał assessment of the shoulder, elbow, and forearm. This may be done rapidly by asking the patient to raisc the hands ovcrhead until the arms touch the ears, to bring the arms down by the sides, to place the hands behind the head, to place the hands behind the back, to place the arms at the sides with the elbows flexed to 90°, then to fully pronate and supinate the forearms, to flex the elbows fully, and to extend the elbows fully. This sequence gives the examiner a brief overview of the rangę of motion of the other joints of the upper extremity and allows the examiner to screen for any gross abnormality that might secondarily affect hand and wrist function.

■ INSPECTION Surface Anatomy

For comfort and convenience, the hand and wrist are usually inspected with the patient and physician seated facing each other. The hands may be rested on a smali table or desk, on a pillow resting on the patient s lap, or on the lap itself. With the hands extended in front of the patient and the forearms pronated, the forearm, hand, and extended fingers should form a straight linę. Any break in that linę is abnormal and requires further inves-tigation.

Orif.ntation

When describing locations in the hand and wrist, the tra-ditional terms anterior, posterior, medial, and lateral are usually replaccd by the terms volar (palmar), dorsal, ulnar, and radial. The ability of the forearm to rotate changes the position of structures in the distal forearm and hand in relation to the rest of the human body; it is thus less confusing to describe them in relationship to surfaces within the hand and wrist. Thus, dorsal refers to the back of the hand and wrist; volar or palmar refer to the anterior surface of the hand and wrist, including the palm; radial refers to the side of the hand and wrist on which the thumb and radius are located; and ulnar refers to the side of the hand and wrist on which the little finger and ulna are located.

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