In human anatomy, the rhomboid minor is a small
skeletal muscle
Skeletal muscles (commonly referred to as muscles) are organs of the vertebrate muscular system and typically are attached by tendons to bones of a skeleton. The muscle cells of skeletal muscles are much longer than in the other types of m ...
on the back that connects 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 eithe ...
with the vertebrae of the
spinal column
The vertebral column, also known as the backbone or spine, is part of the axial skeleton. The vertebral column is the defining characteristic of a vertebrate in which the notochord (a flexible rod of uniform composition) found in all chordat ...
.
Located inferior to
levator scapulae and superior to
rhomboid major
The rhomboid major is a skeletal muscle on the back that connects the scapula with the vertebrae of the spinal column. In human anatomy, it acts together with the rhomboid minor to keep the scapula pressed against thoracic wall and to retract the ...
, it acts together with the latter to keep the scapula pressed against the thoracic wall.
It lies deep to
trapezius but superficial to the long spinal muscles.
Origin and insertion
The rhomboid minor arises from the inferior border of the
nuchal ligament, from 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 ...
es of the seventh
cervical and first
thoracic vertebrae
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 ...
, and from the intervening
supraspinous ligaments.
It is inserted into a small area of the
medial border of the scapula at the level of the
scapular spine.
Action
Together with the rhomboid major, the rhomboid minor retracts the scapula when trapezius is contracted. Acting as a synergist to the trapezius, the rhomboid major and minor elevate the medial border of the scapula medially and upward, working in tandem with the
levator scapulae muscle to rotate the scapulae downward. While other shoulder muscles are active, the rhomboid major and minor stabilize the scapula.
Innervation and blood supply
The nerve supply comes from the
dorsal scapular nerve
The dorsal scapular nerve is a branch of the brachial plexus. It supplies rhomboid major muscle, rhomboid minor muscle, and levator scapulae muscle. It causes the scapula to be moved medially towards the vertebral column. Dorsal scapular ner ...
, with most of its fibers derived from the C5 nerve root and only minor contribution from C4 or C6.
[, p. 4]
The rhomboid minor gets its arterial blood supply from the
dorsal scapular artery
The transverse cervical artery (transverse artery of neck or transversa colli artery) is an artery in the neck and a branch of the thyrocervical trunk, running at a higher level than the suprascapular artery.
Structure
It passes transversely b ...
.
Variation
It is usually separated from the rhomboid major by a slight interval, but the adjacent margins of the two muscles are occasionally united.
['' Gray's Anatomy'' (1918), see infobox]
Additional images
References
External links
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Muscles of the upper limb