Author: Adrian Rad BSc (Hons)•Reviewer: Roberto Grujičić MDLast reviewed: September 30, 2021Reading time: 6 minutes


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The rhomboids room two bilateral, superficial muscles located in the upper back. Castle consist of two functionally similar muscles dubbed rhomboid minor and rhomboid major. Along with trapezius, levator scapulae and latissimus dorsi, they comprise the superficial class of the extrinsic back muscles.

You are watching: The actions of the rhomboid major on the scapula do not include __________.

The rhomboid muscle extend in between the nuchal ligament, spinous procedures of thoracic vertebrae and scapula. Under innervation indigenous the dorsal scapular nerve, the rhomboids primarily retract the scapula superomedially and also rotate the glenoid cavity. Therefore, the rhomboids are crucial to stabilize the scapula into position and reinforce the shoulder.

This short article will talk about the anatomy and role of the rhomboid muscles.

Key facts around the rhomboid muscles
OriginRhomboid minor: Nuchal ligament, Spinous processes of vertebrae C7-T1Rhomboid major: Spinous process of vertebrae T2-T5
InsertionRhomboid minor: root (medial end) the spine the scapulaRhomboid major: Medial border that scapula (from inferior angle to source of spine of scapula)
ActionScapulothoracic joint: paint, etc scapula superomedially, Rotates glenoid cavity inferiorly; Supports place of scapula
InnervationDorsal scapular nerve (C4-C5)
Blood supplyDorsal scapular artery, deep branch the transverse cervical artery, dorsal branch of upper five or 6 posterior intercostal arteries

Contents
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Origin and insertion


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Rhomboid minor is a small, cylindrical muscle that consists of 2 layers; dorsal and also ventral. They partially envelop the levator scapulae inferiorly. Rhomboid minor originates native the nuchal ligament and also spinous processes of the seventh cervical (C7) and also first thoracic (T1) vertebrae. The muscle expand obliquely in one inferolateral direction, come insert into the base of the medial end of the spine the scapula; the dorsal class attaches dorsolateral and also inferior to levator scapulae when the ventral class inserts inferomedially to levator scapulae. At the insertion point of the ventral layer, the fasciae that rhomboid minor and serratus anterior muscles unite. In certain individuals, a thin muscle referred to as rhomboid occipitalis deserve to extend between rhomboid minor and also the occipital bone.

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Rhomboid significant is a wide quadrilateral muscle the originates indigenous the spinous procedures of the 2nd to second to fifth thoracic vertebrae (T2-T5). The muscle expand obliquely in an inferolateral direction to insert into the medial border of scapula, between the inferior angle and root that the spine that scapula. The attachment takes location both top top the dorsal and costal elements of the medial border the scapula.

Learn everything about the superficial ago muscles through our video tutorials, quizzes, labeled diagrams, and articles.


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Superficial muscle of the ago discover study unit
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The rhomboid muscle overlie the deep (intrinsic) muscles of the back and also are covered by the trapezius muscle. The exception is a tiny triangular an ar over the worse border of rhomboid major (triangle that auscultation). This area is bordered through the latissimus dorsi muscle inferiorly, trapezius muscle superomedially and rhomboid significant superolaterally. The is an essential clinical landmark the serves for lung auscultation indigenous the back.

The rhomboids are generally totally separate muscles, but they have the right to be unify in certain individuals. Rhomboid minor partially overlaps the superior part of rhomboid major.

Innervation

Both rhomboid muscles are innervated by the dorsal scapular nerve (C4-C5), a branch the the brachial plexus.

Blood supply

Rhomboid boy and significant receive arterial blood from three sources:


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Function

The main action of the rhomboid muscles is scapular retraction approximately the scapulothoracic joint. Scapular retraction is a simultaneous sliding of the scapula superiorly and also medially along the trunk. This superomedial motion of the scapula rotates the glenoid cavity inferiorly, dropping the shoulder girdle. By opposing excessive scapular protraction, the rhomboids help to keep a correct posture as soon as sitting, standing and also walking. 

In addition, the contraction of the rhomboids fixes and stabilizes the scapula right into position. This provides an anchor suggest in room from which miscellaneous muscles of the upper limb have the right to act and also a fulcrum approximately which the top limb deserve to move.

Take the adhering to quiz to test your understanding on the rhomboids, as well as other superficial muscles of the back!


Clinical relations

The rhomboid muscles have the right to have a an excellent impact on upper body posture and also shoulder mechanics. Poor upper body posture frequently includes a variety of features. One is the the shoulders, and specifically the scapulae, often tend to end up being protracted. This will frequently lead come pain in the upper back, specifically along the medial border of the scapulae. Therefore, strengthening muscles responsible because that scapular retraction, such together the rhomboids, will help relieve the pain and also improve top body posture.

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The consistent postural strain competent by the rhomboid muscles deserve to make them dysfunctional. This can limit the premium rotation of the scapula and also glenoid cavity, leading to bad shoulder mechanics. In turn, soft organization in the shoulder an ar can become injured and painful, especially during activities that involve eight elevation above shoulder height. Such examples encompass sporting tasks like tennis and also volleyball.


Sources

References:

Palastanga, N., & Soames, R. (2012). Anatomy and also human movement: structure and function (6th ed.). Edinburgh: Churchill Livingstone.Standring, S. (2016). Gray"s Anatomy (41tst ed.). Edinburgh: Elsevier Churchill Livingstone.Netter, F. (2014). Atlas of human being Anatomy (6th ed.). Philadelphia, PA: Saunders

Illustrators:

Rhomboid major muscle (dorsal view) - Yousun Koh Rhomboid young muscle (dorsal view) - Yousun Koh