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
Origin	first rib and cartilage
Insertion	subclavian groove of clavicle (inferior surface of middle one third of the clavicle)
Artery	thoracoacromial trunk, clavicular branch
Nerve	subclavian nerve
Actions	depression of clavicle; elevation of first rib
Identifiers
Latin	musculus subclavius
TA98	A04.4.01.007
TA2	2306
FMA	13410
	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, and can lead to thoracic outlet syndrome.[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.

Additional images

Subclavius muscle (shown in red). Humerus and scapula are shown in semi-transparent. Animation.
Subclavius muscle (shown in red).
Anterior surface of sternum and costal cartilages.
Left clavicle. Inferior surface.
The axillary artery and its branches.
The right brachial plexus (infraclavicular portion) in the axillary fossa; viewed from below and in front.
Subclavius muscle - left view
Subclavius muscle- right view
Subclavius (labeled top left) — frontal view

References

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

"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.
Drake, Richard, et al. Gray's Anatomy For Students, Elsevier Inc., 2005
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.
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.

External links

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[Gray's-1918-1] "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.