a. and sb. [a. L. triceps, tricipit-em three-headed, f. TRI- + -cep-s, -cipit-, deriv. form of cap-ut head. Cf. F. triceps (16th c.).]
A. adj. Three-headed (in quot. 1577 loosely, consisting of three heads); spec. of a muscle: Having three heads or points of origin (see B).
1577. Grange, Golden Aphrod., etc., R ij b. The Triceps head of Cerberus.
1804. Abernethy, Surg. Obs., 99. An agitation of fluid was felt beneath the triceps muscle in the inside of the arm.
1881. Mivart, Cat, 96. A rough process or ‘tuberosity,’ into which the triceps muscle is inserted.
B. sb. A triceps muscle; spec. that of the thigh (triceps extensor cruris, t. femoralis) and that of the upper arm (t. extensor cubiti, t. humeralis).
1704. J. Harris, Lex. Techn., I. Triceps, is a Muscle of the Thigh, so called from its three Heads or Beginnings.
1846. Brittan, trans. Malgaigne’s Man. Oper. Surg., 21. The brachial [artery] … between the biceps and the internal portion of the triceps.
1860. O. W. Holmes, Elsie V., iii. (1887), 33. The triceps … furnishes the calf of the upper arm.
Hence † Triceptic a. (nonce-wd.) [irreg. for TRICIPITAL], three-headed.
1716. M. Davies, Athen. Brit., II. To Rdr. 41. Those … Triceptick or Trifaucian Cerberus’s.
