scapula scap·u·la (skāp'yə-lə)
n. pl. scap·u·las or scap·u·lae (-lē')
Either of two large, flat, triangular bones forming the back part of the shoulder. Also called shoulder blade.
|scapula (skāp'yə-lə) Pronunciation Key
(click for larger image in new window)
Plural scapulae (skāp'yə-lē') or scapulas
Either of two flat, triangular bones forming part of the shoulder. In humans and other primates, the scapulae lie on the upper part of the back on either side of the spine. Also called shoulder blade. See more at skeleton.
either of two large bones of the shoulder girdle in vertebrates. In humans they are triangular and lie on the upper back between the levels of the second and eighth ribs. A scapula's posterior surface is crossed obliquely by a prominent ridge, the spine, which divides the bone into two concave areas, the supraspinous and infraspinous fossae. The spine and fossae give attachment to muscles that act in rotating the arm. The spine ends in the acromion, a process that articulates with the clavicle, or collarbone, in front and helps form the upper part of the shoulder socket. The lateral apex of the triangle is broadened and presents a shallow cavity, the glenoid cavity, which articulates with the head of the bone of the upper arm, the humerus, to form the shoulder joint. Overhanging the glenoid cavity is a beaklike projection, the coracoid process, which completes the shoulder socket. To the margins of the scapula are attached muscles that aid in moving or fixing the shoulder as demanded by movements of the upper limb.
Learn more about scapula with a free trial on Britannica.com.