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Coracobrachialis muscle: want to learn more about it?

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Coracobrachialis muscle

Coracobrachialis muscle (Musculus coracobrachialis)

The coracobrachialis is a long and slender muscle of the anterior compartment of the arm. As its name suggests, it extends from the coracoid process of scapula to the shaft of the humerus

The main function of the coracobrachialis muscle is to produce flexion and adduction of the arm at the shoulder joint. Along with the other flexors of the arm (biceps brachii and brachialis muscles), coracobrachialis is innervated by the musculocutaneous nerve.

In this article, we will discuss the anatomy and function of the coracobrachialis muscle.

Key facts about the coracobrachialis muscle
Origin Coracoid process of the scapula
Insertion Anteromedial surface of the humerual shaft
Action Adduction and flexion of the arm at the shoulder joint
Innervation Musculocutaneous nerve (C5- C7)
Blood supply Muscular branches of brachial artery

Origin and insertion

The coracobrachialis is a slender muscle that originates from the deep surface of the coracoid process of scapula.

The muscle fibers run inferolaterally towards the humerus. They insert onto the anteromedial surface of the humeral shaft, between the brachialis muscle and the medial head of triceps

Relations 

The coracobrachialis muscle lies posterior to the pectoralis major muscle and anterior to the tendons of subscapularis, latissimus dorsi, teres major and the medial head of triceps. The muscle is located medial to the biceps brachii and brachialis muscles. The humeral insertion of coracobrachialis is crossed anteriorly by the median nerve. Along with the humerus, coracobrachialis forms the lateral border of the axilla, where it is also the easiest to palpate the muscle.

Innervation

The coracobrachialis muscle is innervated by the musculocutaneous nerve ( C5-C7) a branch of the lateral cord of the brachial plexus.

Blood supply

The coracobrachialis muscle receives its blood supply by the muscular branches of brachial artery. The additional supply comes from the anterior circumflex humeral and thoracoacromial arteries.

Function

The main actions of the coracobrachialis muscle are bending the arm (flexion) and pulling the arm towards the trunk (adduction) at the shoulder joint. When the arm is abducted and extended, the coracobrachialis muscle acts as a strong antagonist to the deltoid muscle.

Clinical relations

The overuse of the coracobrachialis can lead to a hardening of the muscle. Common causes include, among others, bench pressing with extremely heavy weights and carrying heavy loads with hanging arms. A typical symptom is pain in the arm and shoulder, radiating down to the back of the hand.

In more severe cases the musculocutaneous nerve, which goes through the coracobrachialis, can become trapped (entrapment). Clinically, the affected patients show skin sensation disturbances on the radial part of the forearm and a weakened flexion in the elbow, as the nerve also supplies the biceps brachii and brachialis muscles. In contrast, an actual rupture of the coracobrachialis is extremely rare and almost only occurs in serious accidents.
 

Coracobrachialis 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.

Illustrators:

  • Coracobrachialis muscle - Yousun Koh
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