The spine of the scapula or scapular spine is a prominent plate of

bone A bone is a rigid organ that constitutes part of the skeleton in most vertebrate animals. Bones protect the various other organs of the body, produce red and white blood cells, store minerals, provide structure and support for the body, ...

, which crosses obliquely the medial four-fifths of the

scapula The scapula (plural scapulae or scapulas), also known as the shoulder blade, is the bone that connects the humerus (upper arm bone) with the clavicle (collar bone). Like their connected bones, the scapulae are paired, with each scapula on eith ...

at its upper part, and separates the supra- from the

infraspinatous fossa The infraspinous fossa (infraspinatus fossa or infraspinatous fossa) of the scapula The scapula (plural scapulae or scapulas), also known as the shoulder blade, is the bone that connects the humerus (upper arm bone) with the clavicle (coll ...

Structure

It begins at the vertical ertebral or medial borderborder by a smooth, triangular area over which the tendon of insertion of the lower part of the

Trapezius The trapezius is a large paired trapezoid-shaped surface muscle that extends longitudinally from the occipital bone to the lower thoracic vertebrae of the spine and laterally to the spine of the scapula. It moves the scapula and supports th ...

glides, and, gradually becoming more elevated, ends in the

acromion In human anatomy, the acromion (from Greek: ''akros'', "highest", ''ōmos'', "shoulder", plural: acromia) is a bony process on the scapula (shoulder blade). Together with the coracoid process it extends laterally over the shoulder joint. The ac ...

, which overhangs the

shoulder-joint The shoulder joint (or glenohumeral joint from Greek ''glene'', eyeball, + -''oid'', 'form of', + Latin ''humerus'', shoulder) is structurally classified as a synovial ball-and-socket joint and functionally as a diarthrosis and multiaxial join ...

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

Root

The ''root of the spine'' of the

is the most medial part of the scapular spine. It is termed "triangular area of the spine of scapula", based on its triangular shape giving it distinguishable visible shape on x-ray images. The root of the spine is on a level with the tip of the

spinous process The spinal column, a defining synapomorphy shared by nearly all vertebrates, Hagfish are believed to have secondarily lost their spinal column is a moderately flexible series of vertebrae (singular vertebra), each constituting a characteristic ...

of the

third thoracic vertebra In vertebrates, thoracic vertebrae compose the middle segment of the vertebral column, between the cervical vertebrae and the lumbar vertebrae. In humans, there are twelve thoracic vertebrae and they are intermediate in size between the cervical ...

. Gray's Anatomy (1918)
p.1306
/ref> File:Root of spine - left scapula - animation01.gif, Left scapula. Animation. Root of spine is shown in red. File:Root of spine of scapula - animation01.gif, Position of root of spine (shown in red.) Animation. File:Root of spine - left scapula02.png, Medial view of left scapula. Root of spine shown in red. File:Gray203.png, Posterior surface of scapula. Root of spine is not labeled. But visible at center right. File:Root of spine - left scapula01.png , Left scapula. Posterior view. Root of spine shown in red. File:Root of spine of scapula01.png, Posterior view. Root of spine shown in red.

Function

It presents two surfaces and three borders. * Its superior surface is concave; it assists in forming the

supraspinatous fossa The supraspinous fossa (supraspinatus fossa, supraspinatous fossa) of the posterior aspect of the scapula (the shoulder blade) is smaller than the infraspinous fossa, concave, smooth, and broader at its vertebral than at its humeral end. Its ...

, and gives origin to part of the

supraspinatus The supraspinatus (plural ''supraspinati'') is a relatively small muscle of the upper back that runs from the supraspinous fossa superior portion of the scapula (shoulder blade) to the greater tubercle of the humerus. It is one of the four rotat ...

. * Its inferior surface forms part of the

, gives origin to a portion of the

infraspinatus In human anatomy, the infraspinatus muscle is a thick triangular muscle, which occupies the chief part of the infraspinatous fossa.''Gray's Anatomy'', see infobox. As one of the four muscles of the rotator cuff, the main function of the infraspin ...

, and presents near its center the orifice of a

nutrient canal All bones possess larger or smaller foramina (openings) for the entrance of blood-vessels; these are known as the nutrient foramina, and are particularly large in the shafts of the larger long bones, where they lead into a nutrient canal, which e ...

. 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 The trapezius is a large paired trapezoid-shaped surface muscle that extends longitudinally from the occipital bone to the lower thoracic vertebrae of the spine and laterally to the spine of the scapula. It moves the scapula and supports th ...

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 The deltoid muscle is the muscle forming the rounded contour of the human shoulder. It is also known as the 'common shoulder muscle', particularly in other animals such as the domestic cat. Anatomically, the deltoid muscle appears to be made up o ...

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

, below with the neck of the scapula. It forms the medial boundary of the

great scapular notch The great scapular notch (or ''spinoglenoid notch'') is a notch which serves to connect the supraspinous fossa and infraspinous fossa. It lies immediately medial to the attachment of the acromion to the lateral angle of the scapular spine. The ...

, which serves to connect the supra- and infraspinatous fossae.

Additional image

File:Spine of left scapula - animation01.gif, Left scapula seen from behind (spine shown in red). File:Spine of scapula - animation01.gif, Position of spine (shown in red). Animation. File:Gray203.png, Left scapula seen from behind (spine labeled at center top, projecting "out"). File:Posterior surface of scapula.jpg, Left scapula seen from behind (spine labeled at center top). File:Gray205 left scapula lateral view.png, Left

lateral Lateral is a geometric term of location which may refer to: Healthcare *Lateral (anatomy), an anatomical direction * Lateral cricoarytenoid muscle * Lateral release (surgery), a surgical procedure on the side of a kneecap Phonetics *Lateral co ...

view (spine labeled at upper right). File:Spine of left scapula01.png, Left scapula. Lateral view (spine shown in red) File:Orientation.PNG, Surface anatomy of back File:Spine_of_scapula.PNG, Spine of scapula labeled in red, showing muscles attached to it File:Trapezius Gray409.PNG,

Trapezius muscle The trapezius is a large paired trapezoid-shaped surface muscle that extends longitudinally from the occipital bone to the lower thoracic vertebrae of the spine and laterally to the spine of the scapula. It moves the scapula and supports the ...

File:Deltoideus posterior.PNG,

Deltoid muscle The deltoid muscle is the muscle forming the rounded contour of the human shoulder. It is also known as the 'common shoulder muscle', particularly in other animals such as the domestic cat. Anatomically, the deltoid muscle appears to be made up o ...

References

External links

* - "Scapular Region: Scapula (Left)" {{Authority control Scapula