Also 5 comyssure, 6 commyssure. [ad. L. commissūra putting together, joining, f. commiss- ppl. stem of committ-ĕre to put together: see COMMIT and -URE. So F. commissure from 15th c.]
1. A joining or connecting together; the line or surface along which two parts touch each other or form a connection; a joining, juncture, seam.
c. 1420. Pallad. on Husb., V. 42. His comyssure in erthe it stont so depe, And oute of it olyve ayein wol crepe.
1616. Surfl. & Markh., Country Farm, 355. Any chinker, gaping, or rift, betwixt the commissures and joynts of the two barkes.
1624. Wotton, Archit., in Reliq. (1672), 60. The sole Inconvenience or Shaking and Disjoynting the Commissures with so many strokes of the Chizel.
1677. Plot, Oxfordsh., 101. Bent circularly to the hinge or commissure of the valves.
1727–51. Chambers, Cycl., Commissure, in architecture, etc., denotes the joint of two stones.
1759. B. Martin, Nat. Hist. Eng., Stafford., II. 189. Their Striæ not being bent to the Commissure as those of all Oysters are.
1812. Blackw. Mag., LII. 159. The opposite halves … were placed in different hands, and a commissure effected by cementation.
fig. 1678. Cudworth, Intell. Syst., I. iv. § 36. 557. They made the Juncture and Commissure betwixt God and the Creature, so smooth and close, that where they indeed parted, was altogether undiscernible.
2. A joint between two bones; formerly often applied to the seams of the cranial bones.
1541. R. Copland, Guydon’s Quest. Chirurg. Ye commyssures or seames of the brayne panne or skull.
1607. Topsell, Four-f. Beasts (1673), 109. There is no commissure or seam in his scull … but it is a continued bone.
1865. Grote, Plato, II. xxiii. 170. That my bones are held apart by Commissures.
3. The line formed by the meeting surfaces of the two lips, eyelids, etc.
1836. Todd, Cycl. Anat., I. 306/2. There are three eye-lids [in Birds], two of which move vertically, and have a horizontal commissure.
1872. Darwin, Emotions, vii. 193. The commissure or line of junction of the two lips forms a curved line, with the concavity downwards.
b. The connection of the lips, eyelids, etc., at the angles.
1755. Phil. Trans., XLIX. 191. A cancerous tumor … reached from the commissure of the lower lid … of the right eye.
1807–26. S. Cooper, First Lines Surg. (ed. 5), 395. Dr. Cusack made an incision through the lower lip, beginning at its right commissure.
1859. J. Tomes, Dental Surg., 399. The commissure of the lips being drawn back by the first and second finger.
4. Various bands or bundles of white or grey nerve-substance, which connect the two hemispheres of the brain, different parts of the cerebrum and cerebellum, and the two sides of the spinal cord; also, a nerve-cord connecting two ganglia of the nerve system in insects, etc.
The various commissures of the brain and spinal cord are known as anterior, middle, posterior, white, grey, etc., according to their position and color.
1809. Med. Jrnl., XXI. 159. What they say of the commissures of the brain and cerebellum.
1836. Penny Cycl., V. 332/2. The hemispheres of the cerebrum are united chiefly by a broad expansion of medullary matter … called the corpus callosum, or the great commissure of the brain.
1840. G. Ellis, Anat., 21. The chiasma, or commissure of the optic nerves, is a squarish-shaped body.
1842. E. Wilson, Anat. Vade-M., 366. The office of these commissures is the association in function of the two symmetrical portions.
1888. Rolleston & Jackson, Anim. Life, 120. The bands of nerve-fibres uniting the various ganglia are termed ‘commissures’ when they unite the ganglia of the same pair, e.g. the cerebral.
b. A band of muscle, etc., connecting two parts of the animal body.
1870. Rolleston, Anim. Life, 31. Two long delicate bars of cartilage which are … anteriorly connected with each other by a fibrous commissure about the level of the angle of the lower jaw.
5. Bot. a. The line of the cohering faces of two carpels; b. in mosses, the line of junction of two cells, or of the lid and mouth of the sporangium.
1830. Lindley, Nat. Syst. Bot., 236. Bearing the seeds at the commissure along with the valves.
1863. Berkeley, Brit. Mosses, Gloss. 311.
1870. Hooker, Stud. Flora, 149. Umbelliferæ … carpels separated by a commissure.
