Biceps Brachii

Origin, Insertion, Action, Innervation

Origin:
Long head: Supraglenoid tubercle of the scapula (tendon passes through the bicipital groove of the humerus)
Short head: Coracoid process of the scapula (with coracobrachialis)
Insertion: Radial tuberosity and bicipital aponeurosis (lacertus fibrosus) into the deep fascia of the medial forearm
Action:
Primary: Supination of the forearm (strongest supinator when elbow is flexed to 90 degrees)
Flexion of the elbow
Flexion of the shoulder (weak — long head)
Stabilization of the humeral head in the glenoid (long head tendon)
Innervation: Musculocutaneous nerve (C5–C6)

Palpation Guide

Client position: Seated or supine with the elbow flexed to approximately 90 degrees and forearm supinated.
Landmark sequence:

Place your hand on the anterior arm midway between the shoulder and elbow — the prominent muscle belly is the biceps brachii. It is immediately subcutaneous and unmistakable.
Trace the muscle proximally. The two heads merge approximately at the level of the deltoid insertion. The short head lies medial, the long head lateral.
Palpate the long head tendon in the bicipital groove — locate the greater tuberosity (lateral) and lesser tuberosity (medial) of the humerus with the arm in slight external rotation. The groove lies between them. The tendon feels like a firm cord rolling under your finger.
Trace distally to the antecubital fossa. The distal tendon is palpable as a firm cord in the center of the cubital fossa when the client flexes against resistance.
The bicipital aponeurosis fans medially from the distal tendon across the forearm flexor mass — palpable as a thin fascial sheet.

Tissue feel: The muscle belly is soft and pliable when relaxed, becoming rock-hard on contraction. In the bicipital groove, the long head tendon feels like a taut cord approximately the diameter of a pencil.
Confirmation test: Ask the client to supinate the forearm against resistance with the elbow flexed to 90 degrees. You will feel the muscle contract powerfully. Supination is a more specific test than elbow flexion (which also activates brachialis and brachioradialis).
Common errors:
Confusing the long head tendon with the transverse humeral ligament — the ligament bridges the groove and is not independently palpable; what you feel rolling in the groove is the tendon itself.
Missing the distal tendon in the cubital fossa — if the client is not actively flexing, the tendon retracts proximally and becomes difficult to isolate. Have the client resist elbow flexion to make it prominent.
Palpating brachialis and calling it biceps — brachialis lies deep to biceps and is best accessed from the lateral side of the arm, deep to the lateral edge of the biceps belly.

Trigger Point Referral

Common TrP locations: The primary TrP is found in the distal third of the muscle belly, slightly lateral of midline. A secondary TrP may be found in the musculotendinous junction of the long head near the bicipital groove.
Referral pattern: The primary TrP refers superficially over the anterior deltoid region and into the antecubital fossa. The proximal TrP refers into the bicipital groove itself, mimicking bicipital tendinopathy.
Clinical significance: The proximal TrP referral into the bicipital groove mimics biceps tendinopathy — if Speed's test is negative but the client reports anterior shoulder pain in the groove, check for TrPs in the proximal biceps belly before concluding there is tendon pathology.

Trigger point referral diagram — coming soon

Image coming soon. For visual reference, see [Biceps Brachii at TriggerPoints.net](http://www.triggerpoints.net/muscle/biceps-brachii).

Clinical Notes

Innervation significance:

The musculocutaneous nerve (C5–C6) also innervates brachialis and coracobrachialis. Weakness in all three muscles with sensory loss over the lateral forearm (lateral cutaneous nerve of forearm — the terminal sensory branch of the musculocutaneous nerve) indicates musculocutaneous nerve compromise, not isolated biceps pathology.

Common conditions:

Biceps tendinopathy — the long head tendon is vulnerable in the bicipital groove, where it is stabilized by the transverse humeral ligament. Repetitive overhead motions create friction and inflammation. The tendon is also commonly involved in conditions/rotator-cuff-tendinopathy as part of the anterior shoulder pain picture.
Relevant to conditions/subacromial-impingement — the long head tendon passes through the subacromial space and can become compressed between the acromion and humeral head during overhead movement.
The bicipital aponeurosis can compress the median nerve and brachial artery where they pass deep to it in the cubital fossa — relevant to conditions/pronator-teres-syndrome and anterior elbow pain.

What you'll typically find:

In clients with anterior shoulder pain, the bicipital groove is almost always tender. The challenge is distinguishing tendon pathology from referred TrP tenderness. True tendinopathy worsens with resisted supination and Speed's test; TrP-referred pain does not change with resisted tests but reproduces with sustained compression of the muscle belly.
In desk workers, the biceps is often shortened from sustained elbow flexion. The muscle feels dense and "full" rather than pliable. Elbow extension may be slightly limited.

Treatment effects:

Responds well to longitudinal stripping along the fiber direction from the musculotendinous junction to the distal tendon. Cross-fiber friction to the long head tendon in the bicipital groove is effective for chronic tendinopathy but produces significant local soreness — limit initial sessions to 30–60 seconds and warn the client.
The bicipital aponeurosis (lacertus fibrosus) is often overlooked — stripping across this fascial expansion at the medial antecubital fossa can release restriction that mimics distal biceps tightness.

Cautions:

The brachial artery runs medial to the biceps tendon in the cubital fossa — palpable as a pulse. Avoid sustained deep compression medial to the distal biceps tendon.
The median nerve runs medial to the brachial artery in the same area. Deep work in the medial antecubital fossa requires awareness of both structures.
The long head tendon can sublux from the bicipital groove if the transverse humeral ligament is torn — if the tendon "pops" during passive rotation of the humerus, refer for orthopedic assessment.

Clinical pearl:

If a client presents with anterior shoulder pain that does not respond to rotator cuff treatment, check the biceps long head tendon and the biceps TrPs. The biceps is often the overlooked contributor because clinicians focus on the rotator cuff. Speed's test (resisted shoulder flexion with elbow extended and forearm supinated) and Yergason's test (resisted supination with elbow at 90 degrees) help differentiate — but negative tests do not rule out biceps TrPs.

Assessment

Manual muscle testing:

Elbow flexion with supination: Client seated, elbow flexed to 90 degrees, forearm supinated. Apply resistance to the distal forearm into extension. This position emphasizes biceps over brachialis (which flexes regardless of forearm position).

Stretch test:

Combined shoulder extension and elbow extension: Client seated or standing. Extend the shoulder (arm behind the body) with elbow fully extended and forearm pronated. Compare bilaterally. This stretches both heads across both joints simultaneously.

Related special orthopedic tests:

Speed's test — resisted shoulder flexion with elbow extended, forearm supinated (biceps tendinopathy)
Yergason's test — resisted supination with elbow at 90 degrees (bicipital groove pathology)

Muscle Groups

Elbow flexors (functional):

Biceps brachii (this article)
anatomy/muscles/brachialis
anatomy/muscles/brachioradialis
anatomy/muscles/pronator-teres (weak flexor)

Forearm supinators (functional):

Biceps brachii (this article)
anatomy/muscles/supinator

Musculocutaneous nerve group (innervation):

Shoulder flexors (functional — weak role):

Biceps brachii (this article)
anatomy/muscles/coracobrachialis (weak)
Anterior deltoid (primary)

Related Muscles

Synergists for elbow flexion:

anatomy/muscles/brachialis — primary elbow flexor regardless of forearm position; lies deep to biceps
anatomy/muscles/brachioradialis — flexes elbow from neutral forearm position; most active in mid-pronation

Synergist for supination:

anatomy/muscles/supinator — supinates without elbow flexion; most active when elbow is extended

Antagonists:

anatomy/muscles/triceps-brachii — primary elbow extensor; long head also extends the shoulder
anatomy/muscles/pronator-teres — primary pronator; antagonist to supination component

Same innervation (musculocutaneous nerve):

anatomy/muscles/brachialis — shares C5–C6 innervation
anatomy/muscles/coracobrachialis — shares C5–C7 innervation; co-attaches to coracoid process with short head

Key Takeaways

Supination is the primary action — not elbow flexion. Test with resisted supination at 90 degrees of elbow flexion for the most specific activation.
The proximal TrP mimics bicipital tendinopathy — distinguish by checking Speed's/Yergason's before concluding tendon pathology.
The brachial artery and median nerve lie medial to the distal tendon in the cubital fossa — always be aware of neurovascular structures during deep antecubital work.