Coracobrachialis – Anatomy Breakdown

Nov 7

Treadwell, DPT | Muscle by Muscle Series

Watch the Episode

Watch on YouTube: Coracobrachialis – Anatomy Breakdown

In this episode, Dr. Austin Treadwell, DPT breaks down the Coracobrachialis — a small but mighty muscle of the anterior arm that plays a big role in shoulder stability, control, and coordinated movement between the arm and trunk.

Thumbnail for a Coracobrachialis anatomy review video by Austin Treadwell, DPT covering origin, insertion, action, innervation, and clinical tidbits

Overview

The Coracobrachialis sits on the anterior aspect of the arm, deep to the biceps short head.
It originates from the coracoid process of the scapula and runs down to the humerus, acting as a dynamic anchor that guides arm movement through space.

It may be overshadowed by its neighbors (Biceps and Brachialis), but functionally, it’s the link between the shoulder girdle and the upper arm, stabilizing the humeral head during flexion and adduction.

Clinically, it’s a frequent site of musculocutaneous nerve entrapment and often contributes to anterior shoulder discomfort or tightness in pushing patterns.

Origin & Insertion

Origin: Coracoid process of the scapula (shared with the short head of the biceps brachii)
Insertion: Middle third of the medial surface of the humerus

Because it doesn’t cross the elbow, the Coracobrachialis is a pure shoulder mover — giving it a stabilizing edge during flexion and adduction without interfering with distal mechanics.

Function

Primary: Shoulder flexion and adduction
Secondary: Stabilizes the humeral head in the glenoid fossa during arm movement

EMG studies highlight that the Coracobrachialis is most active during mid-range shoulder flexion (45–90°), particularly when resisting load (Hirano et al., 2023).

It quietly co-contracts with the short head of the biceps and the anterior deltoid to stabilize the humerus under tension — making it crucial for pressing stability and shoulder endurance.

Innervation & Blood Supply

Innervation: Musculocutaneous nerve (C5–C7)
Blood Supply: Brachial artery

Clinical & Training Insights

Overuse or tension in the Coracobrachialis can mimic anterior shoulder impingement or biceps tendinopathy.
It’s commonly irritated in athletes with repetitive overhead or pressing movements (swimmers, throwers, lifters).
Palpation deep to the short head of the biceps can reveal local tenderness or referral along the medial arm.
Targeted soft-tissue release and controlled adduction work help restore flexibility and stability.

Clinical note: Musculocutaneous nerve entrapment within the Coracobrachialis may cause weakness in elbow flexion and sensory changes in the lateral forearm — a subtle but key differential diagnosis (Patton et al., 2024).

Clinical Relevance

The Coracobrachialis is often underappreciated in shoulder stability training and rehab.
Rehabilitation emphasizing scapular control and coordinated humeral adduction can reduce anterior shoulder strain and improve press mechanics.
Understanding this muscle helps bridge the gap between shoulder stability and upper-limb power.

Take the Next Step

You’ve got the anatomy down — now put it into motion.
If you’re a clinician, let’s talk shoulder stability and nerve entrapment differentials.
If you’re a lifter or athlete, let’s talk pressing stability and upper-arm control.
And if you’re dealing with anterior shoulder pain or tightness — this is where anatomy meets recovery.

𖤓 Watch more breakdowns on YouTube: Treadwell, DPT – Muscle by Muscle Series
𖤓 Book a Virtual Consultation: TreadwellDPT.com/appointments
𖤓 Download free PT tools & anatomy resources: TreadwellDPT.com/resources

Much more in store; even more to come.
Stay tuned, stay locked. Treadwell, DPT. 🏹

Austin Treadwell