Basic Medical Sciences

 The human scapula bone or the shoulder bone is a flat bone present in the dorsal aspect of the shoulder. The bone has two surfaces, three angles, three borders and three processes. Each of these parts of the scapula bone will now be described in some detail;

The borders of the human scapula bone: As described above the human scapula bone have three borders. These borders are named as Medial border, lateral border and superior border.

Medial border: This is the border of the scapula lying towards the medial side that is towards the back bone. This border is a prominent one and can be traced completely from the top of the bone to the bottom.

Lateral border: This border lies at the lateral side that is towards the shoulder. This border includes the glenoid fossa at which the humerus (arm bone) forms the shoulder joint. The border is also prominent down to the base of the bone.

Superior border: This border is present at the superior aspect but is not as prominent as the other two borders because of the presence of the processes of the scapula bone.

The surfaces of the human scapula bone: The human scapula has two surfaces as described in the top of this article. These surfaces are;

Costal surface: This is the anterior surface of the scapula. It is rather a concave one and forms a fossa called the subscapular fossa. This surface is marked by three longitudinal ridges and a thick lateral ridge adjoining the lateral border.

Dorsal surface: The dorsa surface of the scapula possesses the spine of the scapula which subdivides the dorsal surface into the supraspinous fossa and the infraspinous fossa. The supraspinous fossa is smaller as the spine is towards the superior side and the infraspinous fossa is larger. The two fossae are interconnected with each other by the spinoglenoid notch.

The angles of the human scapula bone: The scapula as described in the start of the article has three angles that are the superior angle, the inferior angle and the lateral angle;

Superior angle: The sides of this angle are formed by the medial border and the superior border.

Inferior angle: The sides of this angle are formed by the medial and the lateral border.

Lateral angle: The sides of this angle are formed by the lateral and the superior border. This angle also includes the glenoid fossa which is directed laterally and upwards.

The processes of the human scapula bone: As described in the start of the article, the scapula has three processes that are spine of the scapula, the coracoid process and the acromion process.

The spine of the scapula: It is present of the dorsal side traversing the dorsal surface of the scapula transversely. It is a thick process and has two surfaces (superior and inferior) and three borders (posterior, superior and inferior). The posterior border is thick and is called the crest of the spine.

The coracoid process: The coracoid process directs forwards and laterally and it arises from the superior aspect of the scapula

The acromion process: The acromion process presents the attachment point for the clavicle bone. It has two borders (medial and lateral) and two surfaces (superior and inferior).