Coracoid process

Structure

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 medially; then, becoming smaller, it changes its direction, and projects forward and laterally.

The component parts of the process are the base; angle; shaft; and apex of the coracoid process, respectively. The coracoglenoid notch is an indentation localized between the coracoid process and the glenoid. As the coracoid process projects laterally, it defines the subcoracoid space beneath.

The ascending portion, flattened from the frontal aspect backward, presents in front a smooth concave surface, across which the subscapularis passes.

The horizontal portion appears flattened when viewed from above looking 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 laterally, on to the upper surface of the horizontal portion, is an elevated ridge for the attachment of the trapezoid ligament.

The coracoid process is a snare molded bone design projecting anterolaterally from the unrivaled(?) part of the scapular neck. Surgeons refer to this part of the body as the “lighthouse of the shoulder” as it is close to the area where structures of veins and nerves (neurovascular) are bound together. The distances between the coracoid base and the neurovascular structures is like a 90 degree chair. The suprascapular ligament is right next to the coracoid process. The muscles that are attached are: pectoralis minor, coracobrachialis, and biceps brachii.

In addition, this structure attaches all the tendons and ligaments together. There are two purposes for this structure: it is the primary hold by which the clavicle is joined to the scapula and alongside the acromion and coraco-acromial tendon, it shapes the curve over the glenoid. By having the coracoid process, this allows the scapula to not be attached to the skeletons by the bone so that it can only support the limbs. Although there are minor instances where the coracoid process can be damaged by itself, there can still be damage to the structure with an acute subscapularis tear. Usually a disruption in the coracoid process can indicate a shoulder injury such as dislocation and instability.

Attachments

It is the site of attachment for several structures:

Muscles

• The pectoralis minor muscle (insertion) – to 3rd, 4th, 5th and on some rare occasions, 6th rib.
• The short head of biceps brachii muscle (origin) – to radial tuberosity.
• The coracobrachialis muscle (origin) – to medial humerus.

Ligaments

• 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