Muscle:Triceps Brachii

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Triceps brachii is the sole extensor of the forearm at the elbow and the only muscle on the posterior surface of the arm. Its three heads — long, lateral, and medial — each harbour trigger points (TrPs) at distinct locations, each with its own referred pain pattern. TrPs in this muscle are common, frequently overlooked, and are an important and under-recognised source of posterior arm pain, epicondyle pain ("tennis elbow"), and hand symptoms. The long head TrPs in particular are a notorious diagnostic blind spot.

Contents

Anatomy

The triceps brachii has three heads, all converging distally on a common tendon — composed of a superficial and a deep lamina that join near insertion — attaching to the olecranon process of the ulna.

  • Long head — arises from the infraglenoid lip of the scapula; spans both the shoulder and elbow joints. This is the only head with a two-joint span.
  • Medial head (sometimes called the deep head) — arises from the posterior surface of the humerus medial and distal to the radial nerve, and from the medial intermuscular septum; lies deep against the bone. Just above the elbow, its attachment covers the posterior humerus both medially and laterally.
  • Lateral head — arises from the posterior surface of the humerus lateral and proximal to the radial nerve, and from the lateral intermuscular septum; bridges the radial nerve and covers much of the medial head.

The medial and lateral heads cross only the elbow joint.

Fibre type composition: The lateral head and long head each contain approximately 60% fast-twitch (Type II) fibres and 40% slow-twitch (Type I) fibres. The medial head is the inverse — approximately 60% slow-twitch — consistent with its role as the primary workhorse of sustained elbow extension.

Innervation: Radial nerve via the posterior cord of the brachial plexus; spinal roots C7 and C8.

Primary actions:

  • All three heads — extension of the forearm at the elbow
  • Long head additionally — adduction of the arm at the glenohumeral joint; the long head also counteracts the tendency of the latissimus dorsi and pectoralis major to depress the humeral head inferiorly out of the glenoid fossa during arm adduction. The medial (deep) head is the workhorse elbow extensor, exhibiting earliest and greatest EMG activity.

Referred Pain Patterns

The triceps brachii has five TrP regions, numbered in order of decreasing clinical prevalence. Distinguishing central TrPs (CTrPs — in the muscle belly) from attachment TrPs (ATrPs — at the musculotendinous junction) is clinically important because their management differs.

TrP1 — Long Head

Location: Central TrP in the belly of the long head, at approximately mid-muscle, a few centimetres distal to where the long head crosses the teres major.

Referred pain: Extends from the central TrP region upward over the posterior arm to the back of the shoulder, occasionally to the base of the neck in the upper trapezius region; downward sometimes over the dorsum of the forearm, skipping the elbow (a clinically useful feature).

Key clinical features:

  • The skipped-elbow pattern — pain in the posterior arm and/or forearm but not the elbow itself — must be present or suspected when posterior arm pain has no elbow component
  • Often a strong component of aching over the posterior shoulder
  • Frequently overlooked because the TrP lies deep and requires pincer palpation to find

TrP2 — Medial Head (Lateral Portion)

Location: Central TrP lying midfibre in the lateral portion of the medial head, in the distal part of the arm, approximately 4–6 cm above the lateral epicondyle.

Referred pain: To the lateral epicondyle; pain may extend to the radial aspect of the forearm.

Key clinical features:

  • A common and often overlooked contributor to lateral epicondyle pain ("tennis elbow")
  • Percussion tenderness of the posterior aspect of the lateral epicondyle persists after inactivation of supinator, biceps brachii, and brachioradialis TrPs — this residual tenderness implicates TrP2
  • Must be considered in any patient with persistent lateral epicondyle pain that fails to resolve with treatment of the forearm extensors

TrP3 — Lateral Head

Location: Central TrP at midbelly in the lateral border of the lateral head, just proximal to the point where the radial nerve exits from the musculospiral groove.

Referred pain: Over the posterior arm, sometimes to the dorsum of the forearm, occasionally to the fourth and fifth digits.

Key clinical features:

  • The taut band of TrP3 may entrap the sensory fibres of the radial nerve (see Nerve Entrapment)
  • Dual symptom presentation is characteristic: aching pain in the fourth and fifth digits from the TrP itself, combined with tingling/numbness over the dorsum of the lower forearm, wrist, and hand to the base of the middle finger from radial nerve compression — these two distributions are distinct and their co-existence should prompt examination of this TrP
  • Responds poorly to stretch-and-spray; injection is usually required

TrP4 — Distal Attachment Region

Location: Attachment TrP deep in the distal medial head, in the region of attachment of all three heads of the triceps brachii, just above the olecranon process.

Referred pain: Distally to the olecranon process; local tenderness at the attachment.

Key clinical features:

  • This is an attachment TrP — almost always secondary to one or more central TrPs (TrP1, TrP3, or TrP5), whose taut bands generate enthesopathic tension at the attachment
  • Primary treatment is directed at the responsible central TrP, not at the attachment site itself
  • Tenderness at the olecranon that has not resolved after treating central TrPs warrants direct injection of the attachment site

TrP5 — Medial Head (Deep/Medial Portion)

Location: Central TrP deep in the medial border of the midfibre region of the medial head, just above the medial epicondyle. Most easily located from an anterior approach with the patient supine and the arm laterally rotated.

Referred pain: To the medial epicondyle; may extend to the volar surface of the fourth and fifth digits, the adjacent palm, and sometimes the middle finger; pain along the inner side of the forearm has also been reported.

Key clinical features:

  • Medial epicondyle pain with extension to the fourth/fifth digits on the volar surface must raise suspicion for TrP5 — this pattern does not come from the more commonly examined lateral-border TrPs
  • Contributes to the tenderness of attachment TrP4

Activation and Perpetuating Factors

  • Sustained elbow-forward posture without support — sitting for extended periods with the elbow held in front of the plane of the chest or abdomen without support (driving, holding paper while writing, needlework, handwork); this is the principal activating mechanism for TrP1 in the long head and is often not suspected by the patient
  • Overuse of forearm crutches
  • A walking cane that is too long (transfers load through the triceps)
  • Short upper arms relative to torso height — increases load from unsupported elbow position
  • Sports strain — backhand "mis-hit" in tennis; overenthusiastic conditioning (push-ups, golf practice)
  • Repetitive forceful elbow extension — manual gear shifting in city driving; pressing stacks of books on a photocopier
  • Jackknife or prolonged surgical positioning with the triceps in stretch
  • Chinning and push-ups (also perpetuators during recovery)

Symptoms

The patient typically complains of vague, difficult-to-localise pain posteriorly in the shoulder and upper arm. Most patients are unaware of any restriction in arm or forearm motion — the tendency is to keep the elbow slightly flexed, out of the painful range, and to compensate for reduced reach with additional scapular or body movement.

Because of referred tenderness to the medial epicondyle (TrP5), the patient may hold the elbow away from the side to avoid body contact. Pain occurs particularly during activities requiring forceful elbow extension: the dominant arm in tennis; the non-dominant arm (elbow held straight) in golf. Pain referred to the vicinity of the elbow joint is sometimes mistakenly attributed to arthritis.

Clinical Examination

Functional Assessment

Both active and passive arm and forearm movements should be tested, as TrPs increase muscle tension and produce measurable dysfunction.

Test Positive finding TrP implicated Must be present / must be absent
Adduction of arm against ear with elbow straight Cannot bring the arm tight against the ear (the shortened triceps will not allow full glenohumeral elevation — Positive Triceps Brachii Test) TrP1 — Long head Must be present: inability to approximate arm to ear without elbow flexion. Must be absent: restricted range must not be from posterior deltoid TrPs alone — palpate both to differentiate.
Simultaneous full elbow flexion + full shoulder elevation Cannot achieve the combined stretch position (elbow maximally flexed, arm fully elevated) TrP1 — Long head Must be present: restriction is simultaneously at both joints, not just one. Must be absent: full passive range at the shoulder when elbow is not flexed — if shoulder range is independently normal, restriction with combined movement implicates the long head.
Straighten elbow against a load (resisted elbow extension) Cannot fully straighten the elbow against resistance; pain on loading TrP2 and/or TrP3 — medial or lateral head Must be present: weakness or pain on resisted extension. Note that passive flexion (stretch) also causes pain.
Percussion of the lateral epicondyle Tenderness on tapping (referred tenderness from TrP2) TrP2 — Medial head (lateral portion) Must be present: percussion tenderness of the posterior aspect of the epicondyle. Must be absent (to implicate TrP2): forearm extensor, supinator, biceps, and brachioradialis TrPs must already have been inactivated — only residual percussion tenderness then implicates triceps TrP2.
Passive elbow flexion (stretch test) Pain on passively flexing the forearm Any central TrP in medial or lateral heads Must be present to confirm triceps involvement when elbow extension is also painful on loading.

When triceps TrPs are suspected, always check the related glenohumeral and elbow joints for normal joint play.

Trigger Point Examination

General principle: to palpate central TrPs, the muscle is lengthened to the beginning of resistance (typically elbow bent 15°–20°) with the arm comfortably supported. To examine for ATrP tenderness, the elbow can be flexed further — increasing tension at the attachment increases ATrP sensitivity.

TrP region Palpation method Position Key finding
TrP1 — Long head Pincer palpation — fingernails must be cut very short; fingertips encircle the muscle, reaching in to the humerus; the long head is lifted from the humerus and its fibres rolled between the digits Supine (arm laterally rotated) or sidelying; arm slightly abducted Clusters of TrPs with multiple taut bands; reproduction of posterior arm and shoulder pain; LTRs often visible and palpable. Pincer palpation skill is itself a test — this TrP is difficult to find without it.
TrP2 — Medial head lateral portion Flat palpation; the TrP is fixed by pressing it against the humerus from both sides Sidelying, arm supported on pillow; elbow bent; lateral border of medial head at the distal arm Taut band; LTR may be visible above and behind the lateral epicondyle; reproduction of lateral epicondyle aching
TrP3 — Lateral head Flat palpation — felt as a nodule at the lateral border of the lateral head, just above the radial nerve exit from the musculospiral groove Sidelying, arm supported Nodule at midbelly; firm palpation along the lateral intermuscular septum near the radial nerve penetration point provokes tingling in the hand — indicating nerve hypersensitivity from the adjacent taut band
TrP4 — Attachment Deep palpation through the thick aponeurosis of all three heads, just above the olecranon Sidelying or supine Spot tenderness only — no LTR; confirmed primarily by the patient's pain response; palpate back along the induration toward the muscle belly to find the responsible central TrP
TrP5 — Medial head medial portion Flat palpation with the patient supine, arm laterally rotated at the shoulder — an anterior approach is needed; the TrP lies deep in the medial border just above the medial epicondyle Supine, arm laterally rotated Spot tenderness reproducing medial epicondyle pain; may also contribute to ATrP4 tenderness

Nerve Entrapment

Radial Nerve — Lateral Head (TrP3)

The TrP3 nodule lies just proximal to the point where the radial nerve exits the musculospiral groove. Taut bands at TrP3 may entrap the sensory fibres of the radial nerve. In cadaveric dissection, an accessory slip of the lateral head originating below the spiral groove was found in almost every body — its attachment to the humerus forms a fibrotic arch of variable tightness over the radial nerve, distinct from the lateral intermuscular septum.

Clinical presentation of radial nerve entrapment:

  • Tingling and numbness (dysaesthesias) over the dorsum of the lower forearm, wrist, and hand to the base of the middle finger — the sensory distribution of the radial nerve
  • This distribution is distinct from the aching referred pain from TrP3 itself, which appears in the fourth and fifth (ulnar) digits
  • Firm palpation along the lateral intermuscular septum at the point of nerve penetration provokes tingling in the hand
  • Clinical and EMG evidence of radial nerve neuropraxia confirms entrapment beneath the triceps

Note: Inactivating TrP3 by injection may produce temporary radial nerve block from local anaesthetic infiltration; the patient should be warned. Using 0.5% procaine, nerve function recovers within 15–20 minutes.

Differential: Lateral elbow pain that mimics TrP2 referral may also be caused by radial nerve entrapment at the arcade of Frohse or other soft tissues over the radial head — distinguish by palpation location and neurological distribution.

Anconeus Epitrochlearis — Ulnar Nerve

An anomalous anconeus epitrochlearis muscle (see Muscle:Anconeus) has been reported as a cause of ulnar compression neuropathy. Excision of the anomalous muscle was curative.

Differential Diagnosis

The triceps brachii is implicated in several common misdiagnoses. The following table focuses on must-be-present and must-be-absent clinical criteria for differentiation.

Condition Must be present to consider this diagnosis Must be absent (excludes or requires reconsideration) Differentiating test or feature
Triceps TrP2 ("tennis elbow" component) Lateral epicondyle pain, worse on resisted extension; taut band with spot tenderness 4–6 cm proximal to lateral epicondyle in the distal medial head Evidence of radial nerve entrapment (arcade of Frohse, posterior interosseous nerve palsy) Residual percussion tenderness of the posterior lateral epicondyle after forearm extensor, supinator, biceps, and brachioradialis TrPs have been inactivated — implicates triceps TrP2
Radial nerve entrapment (TrP3) Tingling/numbness in radial sensory distribution (dorsal forearm, wrist, hand to base of middle finger); TrP3 nodule palpable; provocation of tingling on firm palpation along lateral intermuscular septum Motor deficit affecting wrist/finger extension (motor involvement requires further investigation — radial tunnel syndrome vs posterior interosseous nerve syndrome) Dual distribution: radial sensory symptoms + ulnar-digit aching from TrP3 co-occurring is characteristic of this TrP and not of pure nerve pathology alone
C7 radiculopathy Dermatomal pain and sensory deficit in C7 distribution (posterior arm, forearm, middle finger); may include triceps weakness and diminished triceps reflex Pain confined to posterior arm and hand that exactly matches triceps TrP referral without neurological signs — absence of reflex change or true dermatomal numbness strongly suggests myofascial origin Triceps TrP pain focuses on the back of the arm and extends into the hand — this is sometimes erroneously attributed to C7 radiculopathy. EMG/NCS: radiculopathy slows conduction; myofascial TrPs do not.
Cubital tunnel syndrome (ulnar nerve at elbow) Hypoaesthesia in the ulnar distribution of the hand; weakness and clumsiness of the hand (intrinsic muscle weakness); slowing of ulnar nerve conduction through the cubital tunnel Pain as the dominant or sole symptom — cubital tunnel is more likely to cause weakness and sensory change than pain Ulnar nerve conduction velocity slowing at the elbow confirms cubital tunnel; TrP5 pain to the medial epicondyle does not slow conduction
Medial epicondylitis (golfer's elbow") Medial epicondyle tenderness reproduced by resisted wrist flexion and pronation; pain at the common flexor origin Medial epicondyle pain reproduced specifically by TrP5 palpation in the medial head of the triceps, without forearm flexor involvement Resisted wrist flexion: positive in medial epicondylitis, negative in TrP5 referral. Palpate TrP5 first — it is often overlooked.
Olecranon bursitis Fluctuant swelling over the olecranon; localised posterior elbow swelling Posterior arm pain without localised swelling or fluid — TrP4 enthesopathy does not produce bursal effusion Palpation: olecranon bursitis produces superficial fluctuant swelling; ATrP4 tenderness is deep to the aponeurosis and does not fluctuate
Arthritis of the elbow joint Joint-line tenderness, crepitus, loss of both flexion and extension, radiological changes Pain confined to referred pain pattern without joint-line tenderness or radiological changes Pain from triceps TrPs referred to the elbow vicinity is sometimes mistakenly attributed to arthritis — always palpate for TrPs before accepting this attribution
Thoracic outlet syndrome Upper limb neurogenic symptoms (Roos test, Adson test); vascular changes; TOS confirmed by EMG or imaging Posterior arm pain that is reproduced by TrP palpation without neurogenic or vascular features TOS is a related diagnosis that must be explored when considering triceps TrP presentations — see also Muscle:Pectoralis_Minor

Treatment

Trigger Point Release

Central TrPs (TrP1, TrP2, TrP3, TrP5) respond to stretch and release techniques. Attachment TrP4 requires a different approach — do not apply stretch techniques to it directly.

Protocol for central TrPs — seated:

  1. Position the patient seated; flex the forearm at the elbow to the point of resistance
  2. Apply a few sweeps of vapocoolant spray from proximal to distal, starting at the latissimus dorsi in the posterior axillary fold, continuing over the triceps, around the elbow and down the forearm to include the fourth and fifth fingers (for TrP1, long head)
  3. For the long head: after full elbow flexion, additionally flex the arm at the shoulder joint to achieve full stretch of the two-joint long head
  4. PIR (postisometric relaxation) combined with reciprocal inhibition: instruct the patient to (1) gently press the elbow forward against the operator's resisting hand; (2) breathe in and hold for 6 seconds; (3) breathe out and relax; (4) actively move the arm posteriorly — this last movement uses reciprocal inhibition to further relax the triceps
  5. For medial and lateral heads only: elbow flexion alone is sufficient — arm elevation is not needed as these heads do not cross the glenohumeral joint

Supine position is generally more effective than seated because the patient relaxes more completely. In this position, flex the forearm at the elbow and flex the arm at the shoulder joint so the supinated hand lies beneath the shoulder. Vapocoolant sweeps begin at the latissimus dorsi adjacent to the scapula, covering the triceps distally over the arm and elbow to the wrist. PIR and reciprocal inhibition can be combined as described above.

Full flexion at the shoulder joint may be limited by latissimus dorsi TrPs — release the latissimus before proceeding with the triceps if this is encountered.

Approach to attachment TrP4:

  1. Palpate from the attachment point back along the taut band or induration toward the midfibre region of the muscle to identify the responsible central TrP
  2. Place the muscle in a position of ease (not stretched) and treat the central TrP by non-stretch techniques: trigger point pressure release, deep massage, hold-relax — all may be preceded by vapocoolant or icing
  3. If no central TrP is found, treat the attachment itself with ice massage at the attachment with the muscle in a position of ease; indirect myofascial release; phonophoresis (hydrocortisone ointment, which can be preceded by ice massage); or injection (see below)
  4. Injection of attachment TrPs can expedite pain relief when conservative measures are insufficient

TrP3 responds poorly to stretch and spray; injection is generally required for its inactivation.

Trigger Point Injection

The basic principles of CTrP versus ATrP injection differ (see Concept:Trigger_Point_Injection).

TrP Patient position Key technique points
TrP1 — Long head Supine (anterior approach) or sidelying (posterior approach) Supine: patient laterally rotates the arm so the antecubital space faces upward, abducts slightly to put the long head on slight stretch. Operator encircles the long head in pincer grasp, lifting it away from bone, blood vessels, and the lateral head (beneath which the radial nerve courses). TrP fixed and injected between the fingertips. LTRs are easily seen and felt by the encompassing fingers — they signal effective needle placement.
TrP2 — Medial head lateral Sidelying on uninvolved side, arm on pillow, elbow bent TrP palpated distally in the lateral border of the medial head; fixed by pressing the muscle against the humerus from both sides between the fingers.
TrP3 — Lateral head Sidelying as above TrP3 lies along the lateral border of the lateral head, just above the radial nerve exit. Needle inserted tangentially into a thin muscle layer; directed distally or proximally as convenient. Procaine may infiltrate the radial nerve — temporary partial nerve block expected; with 0.5% procaine, recovery in 15–20 minutes.
TrP4 — Attachment Sidelying, facing away from operator Located only by spot tenderness to deep palpation through the thick aponeurosis; injected deeply toward the olecranon process. Confirmation is by patient's pain response and referred pain report; LTR may occasionally be felt.
TrP5 — Medial head deep Supine, arm laterally rotated, partially abducted, lying on padded operator's lap TrP fixed between fingers; needle directed parallel to muscle fibres, usually upward toward the shoulder. Wide injection spread risks temporary median or ulnar nerve block — avoid.

Corrective Actions

  • Elbow positioning: when typing, writing, reading, or doing handwork, keep the arm vertical with the elbow behind the plane of the chest — not projected forward. An armrest of suitable height should support the elbow whenever possible.
  • Short upper arms: raise the working surface (writing board with padding underneath) or increase armrest height to bring the elbow to the correct level.
  • Forearm crutches: increase use gradually — sudden overload specifically stresses the triceps.
  • Tennis: lighter-weight racquet; racquet not head-heavy; shortening the grip reduces leverage on the elbow extensor.
  • Chinning and push-ups: avoid until recovered; resume progressively.
  • Home stretching: assume the stretch position in Figure 32.6A of the source chapter while seated under a warm shower with water running over the muscle.

Satellite Trigger Points

References

  • Travell JG, Simons DG. Myofascial Pain and Dysfunction: The Trigger Point Manual, Volume 1: The Upper Half of Body. 2nd ed. Baltimore: Williams & Wilkins; 1999. Chapter 32.
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