The coracoid process is a thick curved process attached by a broad base to the upper part of the neck of the scapula; it runs at first upward and medialward; then, becoming smaller, it changes its direction, and projects forward and lateralward.
The ascending portion, flattened from before backward, presents in front a smooth concave surface, across which the subscapularis passes.
The horizontal portion is flattened from above downward; its upper surface is convex and irregular, and gives attachment to the pectoralis minor; its under surface is smooth; its medial and lateral borders are rough; the former gives attachment to the pectoralis minor and the latter to the coracoacromial ligament; the apex is embraced by the Conjoint tendon of origin of the coracobrachialis and short head of the biceps brachii and gives attachment to the coracoclavicular fascia.
On the medial part of the root of the coracoid process is a rough impression for the attachment of the conoid ligament; and running from it obliquely forward and lateralward, on to the upper surface of the horizontal portion, is an elevated ridge for the attachment of the trapezoid ligament.
It is the site of attachment for several structures:
- The pectoralis minor muscle – to 3rd, 4th, 5th and on some rare occasions, 6th rib.
- The short head of biceps brachii muscle – to radial tuberosity.
- The coracobrachialis muscle – to medial humerus.
- The coracoclavicular ligament – to the clavicle. (The ligament is formed by the conoid ligament and trapezoid ligament.)
- The coracoacromial ligament – to the acromion
- The coracohumeral ligament – to the humerus
- The superior transverse scapular ligament – from the base of the coracoid to the medial portion of the suprascapular notch
The coracoid process is palpable just below the lateral end of the clavicle (collar bone).
It is otherwise known as the "Surgeon's Lighthouse" because it serves as a landmark to avoid neurovascular damage.
Major neurovascular structures enter the upper limb medial to the coracoid process, so that surgical approaches to the shoulder region should always take place laterally to the coracoid process.
Analyses of the size and shape of the coracoid process in Australopithecus africanus (STS 7) have shown that in this species it displayed a prominent dorsolateral tubercle placed more laterally than in modern humans.
This reflect, according to one interpretation, a scapula positioned high on a funnel-shaped thorax and a clavicle positioned obliquely as in extant great apes.
Credits to the contents of this page go to the authors of the corresponding Wikipedia page: en.wikipedia.org/wiki/Coracoid process.