Coracobrachialis Muscle

Authors
Affiliations

Nate Yomogida, B.S., SPT

Doctor of Physical Therapy

B.S. in Kinesiology

Chloë Kerstein, B.S., SPT

Doctor of Physical Therapy

B.A. in Neuroscience

Schematic of Pectoralis major and coracobrachialis1 1: Pectoralis Major (clavicular part) 2: Pec Major (Sternocostal part) 3: Pec Major (abdominal part) 4: Coracobrachialis

Schematic of Pectoralis major and coracobrachialis
1: Pectoralis Major (clavicular part)
2: Pec Major (Sternocostal part)
3: Pec Major (abdominal part)
4: Coracobrachialis

Pectoralis Major and Coracobrachialis, anterior view1

Pectoralis Major and Coracobrachialis, anterior view
Reading list
  • Coracobrachialis Muscle
  • MMT

Origin

Coracoid process of Scapula

Figure 1: Left scapula (Posterior view)

Insertion

The coracobrachialis inserts on the medial surface of the middle 1/3 of Humerus (in line with crest of lesser tubercle)

Figure 2: Left Humerus (Anterior view)

Innervation

The musculocutaneous n. and (C5, C6, C7) give innervation to the coracobrachialis muscle.

  • C5 has mild-mod distribution.
  • C6 and C7 have major distribution.

Musculocutaneous n. innervates the muscle as it passes through the muscle.

Action

Since the coracobrachialis originates from the scapula and inserts on the humerus, it primarily affects the glenohumeral joint (GHJ). The coracobrachialis performs

  • GHJ Flexion
  • GHJ Adduction
  • GHJ Internal rotation

When looking at the shoulder as a whole, the coracobrachialis assists with the first 0-60° of shouulder flexion/elevation since this primarily involves the glenohumeral joint.

The coracobrachialis functions to support the anterior shoulder.

Function

Coracobrachialis serves as a secondary flexor and adductor of the shoulder.

The coracobrachialis is usually recruitted when:

  • Scratching your opposite ear.
  • Bench press.
  • Using your forearm to block in front of your chest during combat sports.

Myofascial Functional Unit

The coracobrachialis and pectoralis minor both have insertions on the coracoid process, which creates a myofascial line. When the arm is relaxed by one’s side since the pec minor and coracobrachialis fascial lines run in two different directions, thus the line is inactive. However, when shoulder is brought into overhead flexion (i.e. tennis serve or hanging from a bar).

This connection will combine with other myofascial units to form the Deep front of arm line and the Deep Front Line.

Dysfunction

  • Since the musculocutaneous n. passes through the muscle belly, coracobrachialis dysfunction can entrap the nerve and create neurological symptoms.

Pathologies

Palpation

The coracobrachialis can be found deep to the pectoralis major and Anterior Deltoid. The coracobrachialis is anterior to Axillary artery and brachial plexus, so be mindful when palpating and applying pressure.

Patient position

  • Supine.
  • 45° GHJ abduction.
  • GHJ full external rotation.

Clinician

  • Locate pectoralis major (anterior wall of the axilla).
  • Place one hand on the medial arm, just proximal to the elbow.
  • Place the fingerpads of the other hand into the axilla.
  • Instruct the patient to gently adduct into the non-palpating hand.
  • Palpate the inferior medial edge of the pectoralis major, this will act as a reference point.
  • Dive posterior to pectoralis major into the axilla.
  • Palpate for the “slender” belly of coracobrachialis.
  • Active GHJ adduction should cause it to contract.

Checklist

  • Is the muscle in the medial arm?
  • Is it posterior to pectoralis major?
  • Can you strum along the posterior belly?

Manual Muscle Test (MMT)

According to Dale Avers, the coracobrachialis cannot be isolated in a manual muscle test.

It can, however, be tested alongside other muscles in the shoulder flexion MMT.

Weakness

Coracobrachialis weakness can be caused by musculocutaneous n. dysfunction.

Manual Therapy

1.
Gilroy AM, MacPherson BR, Wikenheiser JC, Voll MM, Wesker K, Schünke M, eds. Atlas of Anatomy. 4th ed. Thieme; 2020.
2.
Donnelly JM, Simons DG, eds. Travell, Simons & Simons’ Myofascial Pain and Dysfunction: The Trigger Point Manual. Third edition. Wolters Kluwer Health; 2019.
3.
Neumann DA, Kelly ER, Kiefer CL, Martens K, Grosz CM. Kinesiology of the Musculoskeletal System: Foundations for Rehabilitation. 3rd ed. Elsevier; 2017.
4.
Weinstock D. NeuroKinetic Therapy: An Innovative Approach to Manual Muscle Testing. North Atlantic Books; 2010.
5.
Gray H. Anatomy of the Human Body. 20th ed. (Lewis WH, ed.). Lea & Febiger; 1918. https://www.bartleby.com/107/
6.
Dutton M. Dutton’s Orthopaedic Examination, Evaluation, and Intervention. 5th ed. McGraw Hill Education; 2020.
7.
Jones B. B Project Foundations. b Project; 2025.
8.
Biel A. Trail Guide to the Body: A Hands-on Guide to Locating Muscles, Bones, and More. 6th ed. Books of Discovery; 2019.
9.
Myers TW. Anatomy Trains. 4th ed. Elsevier; 2021.
10.
Avers D, Brown M. Daniels and Worthingham’s Muscle Testing: Techniques of Manual Examination and Performance Testing. 10th ed. Elsevier; 2019.

Citation

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