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 (: 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 either side ...

at its upper part, and separates the supra- from the infraspinatous fossa.

Structure

It begins at the vertical (vertebral or medial) border by a smooth, triangular area over which the tendon of insertion of the lower part of the Trapezius glides. Gradually becoming more elevated, it ends in the

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

, which overhangs the shoulder-joint. 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 The spine of the scapula or scapular spine is a prominent plate of bone, which crosses obliquely the medial four-fifths of the scapula at its upper part, and separates the Supraspinatous fossa, supra- from the infraspinatous fossa. Structure It b ...

. 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 Each vertebra (: vertebrae) is an irregular bone with a complex structure composed of bone and some hyaline cartilage, that make up the vertebral column or spine, of vertebrates. The proportions of the vertebrae differ according to their spina ...

of the third thoracic vertebra.

Gray's Anatomy ''Gray's Anatomy'' is a reference book of human anatomy written by Henry Gray, illustrated by Henry Vandyke Carter and first published in London in 1858. It has had multiple revised editions, and the current edition, the 42nd (October 2020 ...

(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, and gives origin to part of the

supraspinatus The supraspinatus (: 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 rotator cuff m ...

. * Its inferior surface forms part of the infraspinatous fossa, 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

, 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 fossae.

Additional images

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 also refer to: Biology and healthcare * Lateral (anatomy), a term of location meaning "towards the side" * Lateral cricoarytenoid muscle, an intrinsic muscle of the larynx * Lateral release ( ...

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 human spine, spine and laterally to the spine of the scapula. It moves the scapula and ...

File:Deltoideus posterior.PNG,

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

References

External links

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