Back of the Body and Scapular Region Part-2
POSTERIOR AXIO-APPENDICULAR MUSCLES (MUSCLES CONNECTING SCAPULA WITH THE VERTEBRAL COLUMN PART-2
DEEP POSTERIOR AXIO-APPENDICULAR MUSCLES
Levator Scapulae
Origin
The levator scapula is a slender muscle. It arises by tendinous slips from
(a) Transverse processes of atlas and axis vertebrae, and
(b) Posterior tubercles of the transverse processes of the 3rdand 4th cervical vertebrae
Insertion
The four discrete slips of the muscles fibres descend diagonally towards the scapula to be inserted on to the upper part of its medial border between superior angle and the triangular smooth surface at the medial end of the scapular spine.
Nerve supply
The levator scapulae is innervated by:
(a) Direct branches of C3 and C4 spinal nerves, and
(b) C5 spinal nerve through the dorsal scapulae nerve.
Action
The levator scapulae elevate and steady the scapula during movements of the arm.
Rhomboideus Minor
Origin
The Rhomboideus minor is a thick cylindrical muscle, which arises from;
(a) Lower part of the Ligamentum nuchae, and
(b) Spines of the 7th cervical and 1st thoracic vertebrae.
Insertion
It is inserted on to the base of triangular area at the root of the spine of the scapula.
Rhomboideus Major
Origin
The thin flat Rhomboideus major muscle is about two times wider than Rhomboideus minor. It arise from spine of T2, T3, T4, and T5 vertebrae and intervening supraspinous ligaments.
Insertion
The fibres run downwards and laterally to be inserted on the medial border of the scapula between the root of the spine and inferior angle of the scapula.
Nerve supply of rhomboids
Both the Rhomboideus major and minor are supplied by the dorsal scapular nerve (C5).
Action of the rhomboids
Both the Rhomboideus major and minor retract the scapula as in squaring the shoulders.
Clinical testing of the rhomboids
The rhomboids can be palpated along the medial borders of the scapulae deep to trapezius on bracing the shoulder back against the resistance.
Dorsal scapular nerve(nerve to rhomboids)
The dorsal scapular nerve arises from C5 spinal nerve root in the neck. The nerve pierces the scaleneus medius and comes to lie on the anterior surface of levator scapulae in the posterior triangle of the neck. Here it is accompanied by deep branch of the transverse cervical artery (or dorsal scapular artery). Then the dorsal scapular nerve and artery descend to the back along the anterior surface of the levator scapulae. [ Note: The spinal accessory nerve and superficial branch of the transverse cervical artery runs on the posterior surface of the levator scapulae].