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Subclavius muscle: want to learn more about it?

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Subclavius muscle

Subclavius muscle (musculus subclavius)

The subclavius muscle is a short, triangular muscle of the thoracic wall that lies underneath the clavicle. It originates from the first rib and courses laterally to insert on the undersurface of the middle third of the clavicle.

The main function of the subclavius is to stabilize the clavicle during movements of the shoulder girdle. In addition, it is significant in preventing injuries to the adjacent neurovascular structures due to fractures of the clavicle.

This article will describe the anatomy and functions of the subclavius muscle.

Key facts about the subclavius muscle
Origin Costal cartilage, sternal end of rib 1
Insertion Anteroinferior surface of middle third of clavicle
Innervation Subclavian nerve (C5-C6)
Blood supply Clavicular branch of thoracoacromial artery, suprascapular artery
Function Sternoclavicular joint: Anchors and depresses clavicle

Origin and insertion

The subclavius muscle originates by a strong tendon from the sternal end of the 1st rib, near its articulation with the costal cartilage. The tendon spreads superolaterally into a muscle belly that inserts into the lower surface of the middle third of the body of clavicle (groove for subclavius muscle). 

The subclavius is enclosed by the clavipectoral fascia, which is a fibrous connective tissue that spans the interval between the clavicle and pectoralis minor muscle. The pectoralis major muscle courses superficial to the subclavius and clavipectoral fascia. The brachial plexus, suprascapular artery, subclavian artery and subclavian vein pass deep to the subclavius muscle.

Innervation

The subclavius is innervated by the subclavian nerve (C5-6), a small branch that arises from the superior trunk of brachial plexus.

Blood supply

The subclavius muscle receives arterial blood from the clavicular branch of thoracoacromial artery, with contributions from the suprascapular artery.

Function

The main function of the subclavius muscle is the active stabilization of the clavicle at the sternoclavicular joint during movements of the shoulder and arm. Furthermore, its contraction leads to a depression of the sternal end of the clavicle and subsequent elevation of the first rib. This movement is rather insignificant, but still helps to prevent dislocation of the clavicle at the sternoclavicular joint during certain types of activity.

Additionally, the subclavius is important to prevent injury of the adjacent subclavian blood vessels and the superior trunk of the brachial plexus in case of a fractured clavicle.

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Clinical relations

The vessels and nerves running behind the subclavius muscle can sometimes become entrapped between the clavicle and the first rib, inside the costoclavicular space. This is referred to as costoclavicular syndrome and marks one of the three types of thoracic outlet syndromes (TOS).

This syndrome can be caused by fractures and thoracic deformities, amongst others. Typical symptoms include irritations of the brachial plexus and circulatory disorders of the arm

Subclavius muscle: want to learn more about it?

Our engaging videos, interactive quizzes, in-depth articles and HD atlas are here to get you top results faster.

What do you prefer to learn with?

“I would honestly say that Kenhub cut my study time in half.” – Read more. Kim Bengochea Kim Bengochea, Regis University, Denver

Show references

References:

  • Moore, K. L., Dalley, A. F., & Agur, A. M. R. (2014). Clinically Oriented Anatomy (7th ed.). Philadelphia, PA: Lippincott Williams & Wilkins.
  • Palastanga, N., & Soames, R. (2012). Anatomy and human movement: structure and function (6th ed.). Edinburgh: Churchill Livingstone.
  • Standring, S. (2016). Gray's Anatomy (41tst ed.). Edinburgh: Elsevier Churchill Livingstone.
  • Netter, F. (2014). Atlas of Human Anatomy (6th ed.). Philadelphia, PA: Saunders.
  • Sinnatamby, C. S., & Last, R. J. (2011). Last's anatomy: Regional and applied. (12th edition). Edinburgh: Churchill Livingstone.

Illustrators:

  • Subclavius muscle (Musculus subclavius) - Yousun Koh
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