Biceps Brachii – Anatomy Breakdown

Nov 7

Treadwell, DPT | Muscle by Muscle Series

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Watch on YouTube: Biceps Brachii – Anatomy Breakdown

In this episode, Dr. Austin Treadwell, DPT breaks down one of the most recognizable muscles in the human body — the Biceps Brachii.
You’ll see why it’s far more than a “show muscle,” and how its dual-joint role makes it essential for both performance and protection at the shoulder and elbow.

Thumbnail for a Biceps Brachii anatomy video by Austin Treadwell, DPT covering the muscle's origin, insertion, innervation, action, and clinical insights

Overview

The Biceps Brachii is a two-headed muscle sitting on the anterior upper arm.
It flexes the elbow, supinates the forearm, and plays a dynamic role in shoulder stability — especially during pulling and overhead motions.

Its short head originates medially; its long head crosses the shoulder joint and runs through the bicipital groove.
That dual-attachment design gives it leverage, but also vulnerability — think biceps tendinopathy or SLAP lesions.

Clinically, the Biceps bridges two worlds: upper-limb performance and shoulder integrity.
It’s a muscle you see — but also one you feel every time you catch, carry, or curl.

Origin & Insertion

Short head: Coracoid process of the scapula
Long head: Supraglenoid tubercle of the scapula
Insertion: Radial tuberosity and bicipital aponeurosis into the forearm fascia

The bicipital aponeurosis (a.k.a. lacertus fibrosus) disperses tension across the forearm fascia — one reason the Biceps plays a stabilizing role beyond elbow flexion.

Function

Primary: Elbow flexion and forearm supination
Secondary: Shoulder flexion (long head assists)
Dynamic stability: Helps prevent anterior translation of the humeral head

EMG studies show maximal activation when the elbow is flexed around 80–100° with the forearm supinated (Yoshikawa et al., 2023).
That’s your textbook “curl angle” — where mechanical advantage and fiber alignment peak.

Innervation & Blood Supply

Innervation: Musculocutaneous nerve (C5–C6)
Blood Supply: Brachial artery

Clinical & Training Insights

Overuse at the long head tendon is a common source of anterior shoulder pain in lifters.
Weakness in the Biceps can mask as grip weakness — the two are biomechanically linked during pulling patterns.
Combine eccentric curls with supinated isometrics for both tendon health and hypertrophy.
For shoulder-centric rehab, think of the Biceps as a stabilizer, not just a mover.

Recent imaging data (Kim et al., 2024) shows long-head hypertrophy correlates with shoulder stability improvements in resistance-trained populations.

Clinical Relevance

The Biceps Brachii plays a huge role in overhead and pressing mechanics.
When coordination between its heads is off, you’ll see compensations — shoulder impingement, elbow pain, or forearm tightness.

Rehabilitation should integrate controlled flexion-supination with scapular stability to restore full function across both joints.

Take the Next Step

You’ve got the anatomy down — now put it into motion.
If you’re a clinician, let’s talk shoulder and elbow integration.
If you’re a lifter or athlete, let’s talk arm training that builds power and protection.
And if you’re dealing with pain or tendinopathy — 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