The scapula - 2nd part

I-                   Description:

The scapula is a thin triangular bone. It is composed of:

          -          3 edges: superior, lateral and medial

          -          2 surfaces : anterior and posterior

          -          3 fossae: supra and infra-epinous and subscapular fossa

          -          3 angles: superior, lateral and inferior.

      1-      The anterior surface: The subscapular fossa is the shallow concavity that dominates the anterior surface of the scapula. The oblique ridges cross the subscapular fossa from superolateral to inferomedial.

     2-      The posterior surface: divided by the spine of the scapula into two fossae supra and infra-spinous.

a-       The scapular spine: it passes medio- laterally across the posterior surface, merging medially with the vertebral border and projecting laterally as the acromion process. Its lateral edge forms with the neck of the scapula a notch where fits the suprascapular artery, nerve and vein.

b-      The acromion (or acromial process): is the lateral projection of the scapular spine.

c-       The supraspinous fossa: it is the site of origin of the supraspinatus muscle.

d-      The infraspinous fossa: is the site of origin of the infraspinatus muscle.

    3-      The superior edge: is short and thin. It is separated from the coracoid process by the suprascapular notch. It transmits the suprascapular artery, vein and nerve.

     4-      The medial border: also called the vertebral border, is the straightest, longest and thinnest border. It forms an obtuse angle at the level of the spine of the scapula.

      5-      The lateral border: also called the axillary border. It gets thicker under the glenoidal cavity forming the infraglenoid tubercle where the long chef of triceps anchors.  

       6-      The superior angle: is almost right.

       7-      The inferior angle: is the tip of the scapula

       8-      The lateral angle: contains the coracoid process and the glenoidal cavity supported by the neck.

a-       The coracoid process: finger-like, blunt, rugose projection directed forward and laterally. It anchors 3 muscles: the coracobrachialis muscle, the short chef of the biceps and the pectoralis minor.

b-      The glenoid fossa: is a shallow, vertically elongate concavity that receives the head of the humerus. In its centre, we find the glenoidal tubercle. Its anterior edge is deformed forming the glenoidal notch.

c-       The scapular neck: thick, limited by the supra and the infraglenoid tubercles.