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The spine of the scapula is a prominent plate of bone
Bone

Bones are rigid organ that form part of the endoskeleton of vertebrates. They function to move, support, and protect the various organs of the body, produce red blood cell and white blood cells and store minerals....
, which crosses obliquely the medial four-fifths of the scapula
Scapula

In anatomy, the scapula, omo, or shoulder blade, is the bone that connects the humerus with the clavicle .The scapula forms the posterior part of the shoulder girdle....
 at its upper part, and separates the supra-
Supraspinatous fossa

The supraspinatous fossa of the scapula, smaller than the infraspinatous fossa, is concave, smooth, and broader at its vertebral than at its humeral end; its medial two-thirds give origin to the Supraspinatus....
 from the infraspinatous fossa
Infraspinatous fossa

The infraspinatous fossa of the scapula is much larger than the supraspinatous fossa; toward its vertebral margin a shallow concavity is seen at its upper part; its center presents a prominent convexity, while near the axillary border is a deep groove which runs from the upper toward the lower part....
.

It begins at the vertical border by a smooth, triangular area over which the tendon of insertion of the lower part of the Trapezius glides, and, gradually becoming more elevated, ends in the acromion, which overhangs the shoulder-joint.

The spine is triangular, and flattened from above downward, its apex being directed toward the vertebral border.

Surfaces and borders
It presents two surfaces and three borders.





Of the three borders, the anterior is attached to the dorsal surface of the bone; the posterior, or crest of the spine, is broad, and presents two lips and an intervening rough interval.







The lateral border, or base, the shortest of the three, is slightly concave; its edge, thick and round, is continuous above with the under surface of the acromion, below with the neck of the scapula.






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Encyclopedia


The spine of the scapula is a prominent plate of bone
Bone

Bones are rigid organ that form part of the endoskeleton of vertebrates. They function to move, support, and protect the various organs of the body, produce red blood cell and white blood cells and store minerals....
, which crosses obliquely the medial four-fifths of the scapula
Scapula

In anatomy, the scapula, omo, or shoulder blade, is the bone that connects the humerus with the clavicle .The scapula forms the posterior part of the shoulder girdle....
 at its upper part, and separates the supra-
Supraspinatous fossa

The supraspinatous fossa of the scapula, smaller than the infraspinatous fossa, is concave, smooth, and broader at its vertebral than at its humeral end; its medial two-thirds give origin to the Supraspinatus....
 from the infraspinatous fossa
Infraspinatous fossa

The infraspinatous fossa of the scapula is much larger than the supraspinatous fossa; toward its vertebral margin a shallow concavity is seen at its upper part; its center presents a prominent convexity, while near the axillary border is a deep groove which runs from the upper toward the lower part....
.

It begins at the vertical border by a smooth, triangular area over which the tendon of insertion of the lower part of the Trapezius glides, and, gradually becoming more elevated, ends in the acromion, which overhangs the shoulder-joint.

The spine is triangular, and flattened from above downward, its apex being directed toward the vertebral border.

Surfaces and borders


It presents two surfaces and three borders.

  • Its superior surface is concave; it assists in forming the supraspinatous fossa
    Supraspinatous fossa

    The supraspinatous fossa of the scapula, smaller than the infraspinatous fossa, is concave, smooth, and broader at its vertebral than at its humeral end; its medial two-thirds give origin to the Supraspinatus....
    , and gives origin to part of the Supraspinatus.


  • Its inferior surface forms part of the infraspinatous fossa
    Infraspinatous fossa

    The infraspinatous fossa of the scapula is much larger than the supraspinatous fossa; toward its vertebral margin a shallow concavity is seen at its upper part; its center presents a prominent convexity, while near the axillary border is a deep groove which runs from the upper toward the lower part....
    , gives origin to a portion of the Infraspinatus, and presents near its center the orifice of a nutrient canal.


Of the three borders, the anterior is attached to the dorsal surface of the bone; the posterior, or crest of the spine, is broad, and presents two lips and an intervening rough interval.

  • The Trapezius is attached to the superior lip, and a rough tubercle is generally seen on that portion of the spine which receives the tendon of insertion of the lower part of this muscle.


  • The Deltoideus is attached to the whole length of the inferior lip.


  • The interval between the lips is subcutaneous and partly covered by the tendinous fibers of these muscles.


The lateral border, or base, the shortest of the three, is slightly concave; its edge, thick and round, is continuous above with the under surface of the acromion, below with the neck of the scapula. It forms the medial boundary of the great scapular notch, which serves to connect the supra- and infraspinatous fossę.

Additional image


External links

- "Superficial layer of the extrinsic muscles of the back."