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Coracobrachialis muscle

The coracobrachialis muscle is a slender, elongated muscle of the anterior compartment of the arm. It originates from the apex of the coracoid process of the scapula (in common with the short head of the biceps brachii) and inserts onto the middle third of the medial surface of the humerus.

It is the smallest of the three anterior arm muscles (biceps brachii, brachialis, and coracobrachialis). It lies deep to the biceps brachii and superficial to the brachialis. The muscle is pierced by the musculocutaneous nerve, which supplies it.

The coracobrachialis functions primarily as a flexor and adductor of the arm at the shoulder joint. It also helps stabilize the humeral head against the glenoid cavity during movement.

Synonyms

  • Musculus coracobrachialis

  • Coracoid-humeral muscle

Function

  • Flexes the arm at the shoulder joint

  • Adducts the arm toward the torso

  • Stabilizes the humeral head in the glenoid cavity during motion

  • Acts synergistically with the biceps brachii in forward elevation of the arm

Innervation

  • Musculocutaneous nerve (C5–C7), which pierces the muscle

Blood Supply

  • Brachial artery branches

  • Muscular branches of the anterior circumflex humeral artery

MRI Appearance

T1-weighted images:

  • Muscle belly: intermediate signal intensity

  • Fatty borders: hyperintense fat planes separate muscle from neighbors

T2-weighted images:

  • Muscle fibers: intermediate signal

  • Pathology such as edema, strain, or tear appears hyperintense

STIR:

  • Suppresses fat, highlighting muscle edema, inflammation, or injury as bright hyperintense signal

  • Very sensitive for acute myopathy or strain

T1 Post-Gadolinium (Contrast-enhanced MRI):

  • Normal muscle enhances mildly and uniformly

  • Abnormal enhancement indicates inflammation, infection, tumor, or denervation changes

MRI Non-Contrast 3D Imaging:

  • Provides multiplanar visualization of origin, insertion, and relationship with neurovascular structures

  • Useful in preoperative and trauma planning

CT Appearance

Non-contrast CT:

  • Muscle appears as a soft-tissue density in the medial arm

  • Useful for detecting calcifications, chronic changes, or large masses

CT Post-Contrast:

  • Enhances the coracobrachialis and surrounding soft tissues

  • Helpful in evaluating tumors, abscesses, or traumatic injury

  • 3D CT reconstructions may assist in surgical mapping

MRI images

Coracobrachialis muscle mri axial image 1

MRI images

Coracobrachialis muscle mri axial image

CT image

Coracobrachialis muscle anatomy ct coronal image -img-00000-00000

MRI image

Coracobrachialis muscle axial cross sectional anatomy 3T MRI AI enhanced radiology image-img-00000-00000

MRI image

Coracobrachialis muscle axial cross sectional anatomy 3T MRI AI enhanced radiology image-img-00000-00000_00001

MRI image

Coracobrachialis muscle axial cross sectional anatomy 3T MRI AI enhanced radiology image-img-00000-00000_00002

MRI image

Coracobrachialis muscle sag cross sectional anatomy 3T MRI AI enhanced radiology image-img-00000-00000

CT image

Coracobrachialis muscle ct axial 1

CT image

Coracobrachialis muscle ct axial