Subclavius muscle

Structure

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

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 from manubrium to clavicle between pectoralis major and coracoclavicular fascia. Rarely, the subclavius may be missing entirely.

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

File:Subclavius muscle animation2.gif|Subclavius muscle (shown in red). Humerus and scapula are shown in semi-transparent. Animation. File:Subclavius muscle frontal3.png|Subclavius muscle (shown in red). File:Gray115.png|Anterior surface of sternum and costal cartilages. File:Gray201.png|Left clavicle. Inferior surface. File:Gray523.png|The axillary artery and its branches. File:Gray809.png|The right brachial plexus (infraclavicular portion) in the axillary fossa; viewed from below and in front. File:Slide7b.JPG|Subclavius muscle - left view File:Slide10d.JPG|Subclavius muscle- right view File:1118 Muscles that Position the Pectoral Girdle anterior.png|Subclavius (labeled top left) — frontal view

References

References

1. Drake, Richard, et al. ''Gray's Anatomy For Students,'' Elsevier Inc., 2005
2. [http://www.pjsr.org/Jan13_pdf/8%20Yogesh%20Sontakke.pdf '''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.]
3. (May 2018). "Absence of the subclavius muscle with contralateral subclavius posticus muscle: first imaging report". Clinical Imaging.