Muscle:Teres Minor
Teres minor is the smallest of the four rotator cuff muscles, functioning as a close synergist — a "little brother" — to the infraspinatus. Its trigger points (TrPs) produce a sharply localised pain deep in the posterior deltoid region near the muscle's humeral attachment, felt by the patient as a prune-sized painful "bursitis." A clinically important distinguishing feature is that teres minor TrPs frequently produce referred dysesthesia — tingling and numbness — to the fourth and fifth fingers, a pattern that can be convincingly mistaken for ulnar neuropathy or C8 radiculopathy. Because infraspinatus TrP referred pain to the anterior shoulder typically dominates the clinical picture, teres minor TrPs are usually uncovered only after the infraspinatus has been treated. This secondary presentation is characteristic and distinguishes the teres minor from almost every other shoulder muscle.
Anatomy
The teres minor attaches medially to the upper two-thirds of the dorsal surface of the scapula near its axillary (lateral) border, and to the aponeuroses separating it from the infraspinatus above and the teres major below. It attaches laterally to the lowermost impression (facet) on the greater tubercle of the humerus, immediately adjacent to and just below the infraspinatus attachment. Its tendon is closely applied to the posterior part of the glenohumeral joint capsule.
Anatomical relations: The teres minor lies immediately superior to the teres major. The long head of the triceps brachii passes between them, and together with the teres minor, teres major, and the humerus, these structures define the quadrangular (quadrilateral) space — through which the axillary nerve and posterior circumflex humeral artery pass. This anatomical relationship is clinically important for the differential diagnosis of quadrilateral space syndrome.
Primary actions:
- Lateral rotation of the arm at the glenohumeral joint (in any position — abducted, flexed, or extended)
- Stabilisation of the humeral head in the glenoid cavity during arm movements
- EMG activity increases almost linearly with increasing abduction and during flexion, reaching a peak at approximately 120°; pattern closely parallels that of the infraspinatus
Innervation: Axillary nerve (C5, C6), via the posterior cord of the brachial plexus. This differs from the infraspinatus (suprascapular nerve) and from the teres major below (lower subscapular nerve) — all three muscles are supplied at least in part from C5 and C6 spinal segments.
Functional synergists:
- Lateral rotation: infraspinatus (primary parallel partner), posterior deltoid
- Humeral head stabilisation: supraspinatus, subscapularis (other rotator cuff members)
Functional antagonists:
- Medial rotation: subscapularis, pectoralis major, anterior deltoid
Referred Pain Patterns
The teres minor has a tightly localised essential pain zone and a clinically distinctive neurological referral that is frequently the leading complaint in isolated involvement.
Essential pain zone (present in nearly all patients with active TrPs):
- A concentrated, deep, well-localised pain in the posterior deltoid muscle, close to the muscle's musculotendinous attachment to the humerus — felt by the patient as a prune-sized "painful bursa" deep to the posterior deltoid
- Located proximal to the deltoid tubercle, well below the subacromial bursa
- The point character and deep quality are what lead patients to self-diagnose "bursitis"
Spillover pain zone:
- A broader distribution of aching pain in the region of the posterior deltoid (present in some patients)
Referred dysesthesia (neurological referral):
- Tingling and numbness to the fourth and fifth fingers — reported in a case series to be as common as the posterior shoulder pain itself in patients with isolated teres minor TrP involvement
- This digital dysesthesia may occur with or without demonstrable hypoesthesia and is a referred motor/sensory effect, not true ulnar nerve pathology
Clinical significance: If a patient presents primarily with posterior shoulder pain and a broadly distributed aching in the arm, the teres minor alone is unlikely to be responsible — look for co-involvement of infraspinatus and other muscles.
Activation and Perpetuating Factors
The teres minor is usually not involved as a single-muscle syndrome. Its TrPs are activated by the same overload stresses that activate infraspinatus TrPs — primarily reaching up or reaching out and behind the shoulder. Specific activating events include:
- Motor vehicle accident, particularly when holding on to the steering wheel or reaching the arm out for protection
- Loss of balance while lifting a heavy object overhead
- Working in cramped quarters with the arm reaching overhead
- Playing volleyball (overhead reaching and striking)
- Any acute overload from reaching behind the shoulder
TrPs are perpetuated by continued overloading of the muscle when reaching up and back, and by systemic perpetuating factors (see Concept:Perpetuating_Factors).
Clinical Examination
Subjective Presentation
The subjective profile of teres minor TrPs has features that clearly distinguish it from the infraspinatus and from neurological conditions that it mimics.
Cardinal subjective features:
| Feature | Detail |
|---|---|
| Pain location | Posterior deltoid region, close to the humeral attachment — not the front of the shoulder; the patient points to the back of the shoulder near the deltoid, not the anterior joint |
| Quality | Deep, sharply localised — like a prune-sized painful "bursa"; the deep point character is characteristic and leads to the patient's self-report of "bursitis" in the back of the shoulder |
| Digital dysesthesia | Tingling and numbness to the 4th and 5th fingers — may be the presenting complaint in isolated teres minor involvement; occurs with shoulder activity, especially reaching above shoulder height or behind the body |
| Aggravating movements | Reaching up and back; reaching above shoulder height; overhead activities |
| Relationship to infraspinatus | Teres minor pain is typically revealed after infraspinatus treatment — the patient's anterior shoulder pain resolves, and the posterior shoulder pain with digital dysesthesia becomes the new dominant complaint |
| Restricted motion complaint | Less prominent than in infraspinatus involvement — patients complain more of pain than of movement restriction |
Key differentiating history questions:
| Question | Significance |
|---|---|
| "Where is the worst pain — front or back of the shoulder?" | Teres minor: posterior deltoid / back of shoulder. Infraspinatus: deep front of joint (patient covers front of shoulder with hand). This is the single most useful history question. |
| "Do you have tingling or numbness in your fingers? Which ones?" | 4th and 5th fingers → teres minor TrP referred dysesthesia; this must not be assumed to be ulnar neuropathy without electrodiagnostic evaluation |
| "Has the shoulder pain shifted — did it used to be in the front and is now in the back?" | Yes → classic teres minor presentation emerging after infraspinatus treatment; the infraspinatus pain dominated and release uncovered the underlying teres minor involvement |
| "Does reaching behind or above you bring on the numbness in your fingers?" | Yes → teres minor TrP activity; movement-provoked digital dysesthesia is a characteristic feature |
| "Was there a recent car accident where you were gripping the wheel?" | Yes → consider teres minor alongside infraspinatus and other rotator cuff muscles; also rule out acromioclavicular separation |
Differential history features — teres minor vs the most important mimics:
| Feature | Teres minor TrPs | Infraspinatus TrPs | Ulnar neuropathy | Quadrilateral space syndrome |
|---|---|---|---|---|
| Primary pain location | Posterior deltoid near humeral attachment | Deep anterior shoulder joint (patient covers front with hand) | Variable — forearm and hand; little elbow pain specific to the muscle | Posterior shoulder; deltoid wasting |
| Digital symptoms | 4th–5th finger dysesthesia (tingling/numbness); movement-provoked | No finger symptoms in isolation | Constant 4th–5th finger numbness; not movement-specific in early stages | None typically |
| Objective neurological deficit | None — dysesthesia is referred, not neuropathic; electrodiagnostics normal | None | Present — measurable ulnar sensory and motor conduction slowing | Teres minor atrophy on MRI; axillary nerve compression |
| Behind-the-back test | Slightly restricted in Hand-to-shoulder Blade Test after infraspinatus inactivation | Severely restricted — barely reaches hip pocket | Normal | May be restricted |
| Pain arc !! Throughout or at end of range | Throughout or end of range | No arc pain | Small arc pattern possible | |
| Occurrence pattern | Almost always follows or accompanies infraspinatus involvement | Independent of shoulder muscles | Typically presents after trauma or compression |
Active Range of Motion
Hand-to-shoulder Blade Test: The teres minor usually shows slight restriction of medial rotation at the glenohumeral joint on this test — less severe than the marked restriction seen with infraspinatus TrPs. The significance of finding residual restriction on this test after infraspinatus treatment has been fully performed is that teres minor TrPs are the likely cause.
Clinical sequence: the Hand-to-shoulder Blade Test remains restricted → infraspinatus treated → some improvement but residual restriction → teres minor TrPs are responsible for the remaining limitation.
Mouth Wrap-around Test: May also be restricted with active teres minor TrPs.
Pain pattern during movement:
- Unlike rotator cuff structural pathology, teres minor TrPs do not produce a small severe arc of pain — the pain is throughout the movement or at the end of range of movement. Localised arc pain should prompt evaluation for a rotator cuff tear.
Teres Minor Trigger Point Examination
The teres minor lies between two easily palpated muscles along the lateral border of the scapula:
- Above: infraspinatus
- Below: teres major
- Laterally: the quadrangular space (through which the axillary nerve passes)
Patient position: Patient lies on the side opposite the involved upper limb; the uppermost (involved) arm rests on a pillow against the chest.
Palpation:
- The lateral border of the scapula is the key orienting landmark — usually palpable in the space between the teres minor and teres major when using pincer palpation
- Palpate along the lateral edge of the scapula, between the infraspinatus (above) and the teres major (below), to locate active TrPs in the parallel fibres of the teres minor
- TrPs usually lie near the surface of the muscle, close to the lateral border of the scapula
Confirmation by differential contraction: The teres minor can be specifically identified by having the patient alternately attempt lateral and medial rotation of the arm against minimal resistance:
- Contracts (and becomes firmer) during lateral rotation
- Relaxes during medial rotation
This differential contraction test allows the examiner to distinguish the teres minor from the adjacent teres major (which contracts on medial rotation) when the anatomy is unclear.
Palpation note: TrPs are commonly found not only at the standard X location but also slightly medial to this position along the scapular border.
Screening Tests
- Hand-to-shoulder Blade Test — the primary objective screen; slight restriction remaining after infraspinatus inactivation points to teres minor TrPs (see Hand-to-shoulder Blade Test)
- Mouth Wrap-around Test — may be restricted; less specific than the Hand-to-shoulder Blade Test for this muscle (see Mouth Wrap-around Test)
Differential Diagnosis
Ulnar Neuropathy
The fourth and fifth finger dysesthesia referred by teres minor TrPs can be convincingly mistaken for ulnar neuropathy. Distinguishing features:
- Teres minor TrPs: dysesthesia is movement-provoked (by reaching above or behind); electrodiagnostic studies are normal; teres minor TrP palpation reproduces the digital symptoms
- Ulnar neuropathy: sensory deficit is typically constant or positional (elbow flexion) rather than shoulder-movement-provoked; electrodiagnostics show abnormal ulnar sensory and/or motor conduction
- Always rule out with electrodiagnostic evaluation before attributing ulnar distribution symptoms to teres minor TrPs
C8 Radiculopathy
C8 radiculopathy also produces fourth and fifth finger symptoms. Distinguishing features:
- C8 radiculopathy: typically includes neck pain, dermatomal pattern, myotomal weakness, reflex changes, and positive electrodiagnostic findings
- Teres minor TrPs: no neck symptoms; symptoms provoked by shoulder movement; no objective neurological deficit; normal electrodiagnostics
- Both conditions may coexist
Quadrilateral Space Syndrome
The quadrilateral space syndrome involves compression of the axillary nerve by fibrous bands as it passes through the quadrangular space (bounded by the teres minor, teres major, long head of triceps brachii, and the humerus). It is characterised by:
- Posterior shoulder pain
- Selective atrophy of the teres minor muscle on MRI — this is pathognomonic and distinguishes it from teres minor TrPs, which do not produce atrophy
- Point tenderness over the quadrangular space
Confirmed by MRI demonstrating selective teres minor atrophy.
Subdeltoid Bursitis
The sharply localised deep pain referred by teres minor TrPs to the posterior deltoid region closely mimics subdeltoid bursitis. The posterior deltoid location, well below the subacromial bursa, is the key distinguishing feature. Always examine the teres minor for TrP activity before attributing posterior deltoid pain to bursitis.
Rotator Cuff Tear
With teres minor TrPs, the patient does not describe a small arc of severe pain — pain is throughout the movement or at end range. A severe, small-arc pain pattern should prompt evaluation for rotator cuff tear. If a tear is suspected, non-stretching treatment methods must be used (see Treatment below).
Acromioclavicular Separation
In cases of posttraumatic shoulder pain, particularly following a motor vehicle accident in which the patient was gripping the steering wheel or reaching the arm out for protection, rule out acromioclavicular separation before proceeding to TrP treatment.
Infraspinatus TrPs
The infraspinatus is the primary synergist of the teres minor and almost always becomes involved when teres minor TrPs are active. The characteristic sequence is:
- Infraspinatus TrPs active → deep anterior shoulder pain dominates
- Infraspinatus treated → anterior pain resolves; posterior shoulder pain and 4th–5th finger dysesthesia emerge as the new primary complaint
- Teres minor TrPs identified and treated
This sequential unmasking is pathognomonic for the infraspinatus-teres minor pairing.
Treatment
Precaution
If a rotator cuff tear is suspected, non-stretching treatment must be employed: TrP pressure release, deep massage to the taut band, gentle hold-relax, indirect techniques, and/or injection. Restore scapular mobility and joint play before or alongside TrP treatment.
Trigger Point Release
Primary spray and stretch position:
- Patient lies on the side opposite the involved muscle
- Operator first applies a few sweeps of vapocoolant spray over the muscle while flexing the arm to bring it overhead and far enough behind the head to take up slack
- With successive spray applications, the operator gradually releases the muscle by allowing the arm to drop down behind the head and toward the floor
- Parallel sweeps of vapocoolant are applied along the line of the muscle fibres and over the pain reference zone (posterior deltoid)
- Hot packs over the muscle follow treatment
Additional stretch positions: The positions described for infraspinatus spray and stretch (arm across the front of the chest, and hand behind the ipsilateral pelvis in sidelying) can also be used to lengthen the teres minor (see Infraspinatus stretch positions).
Release facilitation: Postisometric relaxation and/or reciprocal inhibition are particularly effective for this muscle (see Concept:Apropos_of_All_Muscles).
Trigger Point Injection
Patient position: Lying on the unaffected side with the involved arm resting on a pillow in front. Alternatively, prone with the arm medially rotated (palm up) and abducted to approximately 45° or less, to take up slack in the muscle.
TrP location: TrPs in the teres minor usually lie near the surface of the muscle, between the teres major and the infraspinatus, near the lateral border of the scapula.
Technique:
- Fix the TrP between the index and middle fingers (same technique as described for the infraspinatus — see Infraspinatus injection)
- The needle is directed toward the scapula
- The tip of the index finger marks the lateral border of the scapula between the teres major and teres minor as an orienting landmark
Post-injection: The patient performs the Hand-to-shoulder Blade Test movement to stretch the muscle while vapocoolant is applied over it. Hot packs and active range of motion complete the treatment.
Self-Treatment
- Tennis ball / Theracane® compression: The patient lies on a tennis ball placed under a tender spot in the teres minor and rolls the TrP over it using body weight. A Theracane® may be used instead. These techniques are identical to those recommended for the infraspinatus.
- Family-assisted TrP pressure release: A member of the patient's family can be taught to apply digital trigger point pressure release to this superficially located muscle.
Patient Education
Activity Modification
- Avoid excessive or repetitive overhead reaching and backward-reaching movements during the recovery period
- In a motor vehicle, use headrests correctly and be aware that bracing with the arms during a crash can acutely overload both the teres minor and infraspinatus
Sleep Positioning
- Position the arm to avoid full shortening during sleep — the same principles as for infraspinatus (a pillow supporting the uppermost arm in neutral when lying on the pain-free side)
- Apply hot packs to the muscle before retiring
Satellite Trigger Points
The teres minor is almost always involved together with the infraspinatus:
- Muscle:Infraspinatus — the primary synergist and almost always involved when teres minor TrPs are active; treat the infraspinatus first — teres minor TrPs are frequently uncovered only after infraspinatus treatment
- Muscle:Supraspinatus — fellow rotator cuff member; the supraspinatus-infraspinatus team is commonly co-active; teres minor involvement may extend the complex
- Muscle:Deltoid (posterior) — functional synergist for lateral rotation; may develop satellite TrPs
- Muscle:Teres_Major — anatomical neighbour; shares activation patterns from reaching overhead and back
Related Pages
- Pain:Upper_Back_and_Shoulder — Diagnostic algorithm for upper back and shoulder pain
- Muscle:Infraspinatus — Primary synergist; almost always co-active; the infraspinatus pain dominates and masks teres minor until treated
- Muscle:Supraspinatus — Fellow rotator cuff member; differential for arc-of-pain presentation
- Muscle:Subscapularis — Primary antagonist for medial rotation
- Muscle:Teres_Major — Anatomical neighbour; differential for axillary border pain
- Differential:Thoracic_Outlet_Syndrome — Ulnar-distribution finger symptoms must be distinguished from lower trunk entrapment
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 23.
- Travell JG, Simons DG. Myofascial Pain and Dysfunction: The Trigger Point Manual, Volume 1. 2nd ed. Chapter 18 (Overview of the Upper Back, Shoulder, and Arm Region).