Subclavius muscle

Subclavius muscle
Subclavius muscle (shown in red).
Deep muscles of the chest and front of the arm, with the boundaries of the axilla. (Subclavius visible at upper left, above first rib.)
Details
Originfirst rib and cartilage
Insertionsubclavian groove of clavicle (inferior surface of middle one third of the clavicle)
Arterythoracoacromial trunk, clavicular branch
Nervesubclavian nerve
Actionsdepression of clavicle
elevation of first rib
Identifiers
Latinmusculus subclavius
TA98A04.4.01.007
TA22306
FMA13410
Anatomical terms of muscle

The subclavius is a small triangular muscle, placed between the clavicle and the first rib.[1] Along with the pectoralis major and pectoralis minor muscles, the subclavius muscle makes up the anterior axioappendicular muscles, also known as anterior wall of the axilla.[2]

Structure

It arises by a short, thick tendon from the first rib and its cartilage at their junction, in front of the costoclavicular ligament.[1]

The fleshy fibers proceed obliquely superolaterally, to be inserted into the groove on the under surface of the clavicle.

Innervation

The nerve to subclavius (or subclavian nerve) innervates the muscle. This arises from the junction of the fifth and sixth cervical nerves, from the superior/upper trunk of the brachial plexus.

Variation

Insertion into coracoid process instead of clavicle or into both clavicle and coracoid process. Sternoscapular fasciculus to the upper border of scapula. Sternoclavicularis[3] from manubrium to clavicle between pectoralis major and coracoclavicular fascia.[1] Rarely, the subclavius may be missing entirely.[4]

Function

It depresses the lateral clavicle, acts to stabilize the clavicle while the shoulder moves the arm. It also raises the first rib while lowering the clavicle during breathing.

The subclavius protects the underlying brachial plexus and subclavian vessels from a broken clavicle - the most frequently broken long bone[5]

Additional images

References

Public domain This article incorporates text in the public domain from page 438 of the 20th edition of Gray's Anatomy (1918)

  1. 1 2 3 "IV. Myology: 13". Gray's Anatomy: The Muscles Connecting the Upper Extremity to the Anterior and Lateral Thoracic Walls. 1918. Archived from the original on 2014-03-08.
  2. ↑ Drake, Richard, et al. Gray's Anatomy For Students, Elsevier Inc., 2005
  3. ↑ Sternoclavicularis is a rare muscle found in a large triangular gap between the sternocostal and clavicularheads of Pectoralis Major muscle on the right side during routine cadaveric dissection.
  4. ↑ Yun, Sam; Park, Sekyoung; Kim, Chang Su (May 2018). "Absence of the subclavius muscle with contralateral subclavius posticus muscle: first imaging report". Clinical Imaging. 49: 54–57. doi:10.1016/j.clinimag.2017.10.008. ISSN 0899-7071. PMID 29127878.
  5. ↑ ?
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