Knuckle

The dorsal aspect of the flexed metacarpophalangeal joint. Knuckle may be shorter and simpler to say.

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1. A joint of a finger when the fist is closed, especially a metacarpophalangeal joint. 2. A kink or loop of intestine, as in a hernia. [M.E. knokel]

- aortic k. the contour of the aortic arch protruding from the mediastinal silhouette in an anteroposterior (AP) radiograph of the chest.

- cervical aortic k. an anomalous aortic arch in which the aorta extends into the neck and forms an anteroposterior arch, which may be as high as the hyoid bone; the common carotid artery of one side is given off from the summit of the arch, and the common carotid of the other side arises from the more proximal part of the aorta; the pulsating arch may be mistaken for an aneurysm, but the radial pulses are equal.

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knuck·le 'nək-əl n

1 a) the rounded prominence formed by the ends of the two adjacent bones at a joint used esp. of those at the joints of the fingers

b) the joint of a knuckle

2) a sharply flexed loop of intestines incarcerated in a hernia

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knuck·le (nukґəl) the dorsal aspect of any phalangeal joint, especially of the metacarpophalangeal joints of the flexed fingers. By extension sometimes applied to any anatomical structure of similar appearance, such as an extruded loop of intestine in hernia.