Rhomboids

Rhomboids
Rhomboid Major
Structure
The rhomboid major arises from the spinous processes of the thoracic vertebrae T2 to T5 as well as the supraspinous ligament. It inserts on the medial border of the scapula, from about the level of the scapular spine to the scapula's inferior angle. The rhomboid major is considered a superficial back muscle. It is deep to the trapezius, and is located directly inferior to the rhomboid minor. As the word rhomboid suggests, the rhomboid major is diamond-shaped. The major in its name indicates that it is the larger of the two rhomboids.
INNERVATION AND BLOOD SUPPLY
The rhomboid major, like the rhomboid minor, is innervated by the ventral primary ramus via the dorsal scapular nerve (C5). Both rhomboid muscles also derive their arterial blood supply from the dorsal scapular artery.
ACTIONS
The rhomboid major helps to hold the scapula (and thus the upper limb) onto the ribcage. It also acts to retract the scapula, pulling it towards the vertebral column, and downwardly rotates the scapula with respect to the glenohumeral joint. It works collectively with the levator scapulae to elevate the medial border of the scapula.

Origin
spinous processes of the T2 to T5 vertebrae
Insertion
medial border of the scapula, inferior to the insertion of rhomboid minor muscle

Artery
dorsal scapular artery

Nerve
dorsal scapular nerve (C4 and C5)

Actions
Retracts the scapula and rotates it to depress the glenoid cavity. It also fixes the scapula to the thoracic wall.



Antagonist
Serratus anterior muscle

Origin
spinous processes of the T2 to T5 vertebrae
Insertion
medial border of the scapula, inferior to the insertion of rhomboid minor muscle

Artery
dorsal scapular artery

Nerve
dorsal scapular nerve (C4 and C5)

Actions
Retracts the scapula and rotates it to depress the glenoid cavity. It also fixes the scapula to the thoracic wall.

Antagonist
Serratus anterior muscle

Muscles connecting the upper extremity to the vertebral column. (Rhomboideus major visible at upper center right, near shoulder.)
Latin
musculus rhomboideus major
Gray's
subject #121 434

Origin
spinous processes of the T2 to T5 vertebrae
Insertion
medial border of the scapula, inferior to the insertion of rhomboid minor muscle

Artery
dorsal scapular artery

Nerve
dorsal scapular nerve (C4 and C5)

Actions
Retracts the scapula and rotates it to depress the glenoid cavity. It also fixes the scapula to the thoracic wall.

Antagonist
Serratus anterior muscle