Muscle:Abdominal Wall/Belch Button

The belch button is an uncommon but clinically important trigger point (TrP) that has not been consistently localised to a specific named muscle. It is a dorsal TrP that may lie in the posterior fringe of the external oblique, or it may be a fascial TrP in the lumbodorsal fascia, or it may represent an attachment TrP of the transversus abdominis where it attaches to the thoracolumbar fascia at the angle of the twelfth rib. It is included as a separate page because its clinical presentation — spontaneous, involuntary belching and projectile vomiting — is highly distinctive and may not be recognised as myofascial in origin, and because it represents a serious postoperative complication risk.

Location

The belch button is found on the left or right side, usually at or just below the angle of the twelfth rib, in the most posterior abdominal wall musculature or in the connective tissue of this region.

Key physical finding: When located by palpation, a rib is palpable beneath the examining finger. This is the defining anatomical landmark for identifying the correct location.

It has not been consistently localised to a single muscle and may represent:

• A TrP in the posterior fringe of the external oblique at the level of its most lateral and posterior fibres
• A fascial TrP in the lumbodorsal fascia
• An attachment TrP of the transversus abdominis at its posterior attachment to the thoracolumbar fascia near the twelfth rib angle

Somatovisceral Effects

Unlike most abdominal TrPs, the belch button does not primarily produce a referred pain pattern felt by the patient as pain. Instead, its principal effect is somatovisceral:

• When sufficiently active, causes spontaneous, involuntary belching
• In severe cases, projectile vomiting
• The patient is likely to complain of a "stomach problem" with much belching of gas

Supporting clinical observations:

• Gutstein reported 7 patients who responded with belching following injection of "fibrositic spots" (interpreted as TrPs) in the abdominal musculature; a few patients belched in response to pressure applied to tender abdominal spots
• Alvarez reported that some patients belched every time the physician touched a trigger area in the back
• When the TrP is pressed and the patient belches as pressure is applied, this constitutes a positive provocation test and confirms the diagnosis

Clinical Significance — Postoperative Risk

Projectile vomiting from an active belch button TrP represents a serious postoperative complication. A patient harbouring an active belch button TrP who undergoes abdominal or other surgery may experience projectile vomiting in the recovery period — carrying risks of aspiration and wound dehiscence. This presentation is deeply embarrassing to clinical staff who are unaware of the myofascial cause.

Preoperative screening: Patients with a history of excessive belching, particularly if provocation of the TrP at the twelfth rib angle elicits belching, should have the TrP inactivated before surgery.

Activation and Perpetuating Factors

• Visceral disease affecting the upper gastrointestinal tract
• Acute trauma to the posterior lateral abdominal wall
• Chronic occupational strain in a sustained twisted posture
• The same perpetuating factors as for the external oblique and transversus abdominis
• Satellite TrP activation from key TrPs in the paraspinal muscles at the T12 level or in the quadratus lumborum

Clinical Examination

1. Locate the angle of the twelfth rib on the affected side — the most posterior and inferior bony landmark of the rib cage on that side
2. Apply flat palpation just at or below this angle, pressing into the posterior abdominal wall musculature or lumbodorsal fascia
3. A rib must be palpable beneath the examining finger — this confirms correct location
4. Apply steady, increasing pressure
5. If the patient belches as pressure is applied, the diagnosis is confirmed

The TrP may be on either the left or right side and may be bilateral. Bilateral involvement may give rise to bilateral belching provocation.

Differential Diagnosis

Condition	Distinguishing features
Gastro-oesophageal reflux disease (GORD)	Acid reflux belching associated with heartburn, regurgitation, worse when supine or postprandially; pH monitoring and endoscopy differentiate; TrP pressure at the twelfth rib angle reproduces and may provoke belching in the myofascial case
Aerophagia / functional belching	Habitual air swallowing, often associated with anxiety; belch button TrP is a specific, localised, palpable point — distinguished by direct provocation during palpation
Small intestinal bacterial overgrowth (SIBO)	Excessive gas and belching with bloating; hydrogen breath test differentiates; may coexist with TrPs
Hiatal hernia	Upper GI series and endoscopy; hiatal hernia and belch button TrP may coexist — the TrP is a myofascial component of the symptom complex that can be independently treated
Postoperative nausea and vomiting	In the postoperative context, projectile vomiting from a belch button TrP may be misattributed to ileus or obstruction — distinguished by absence of abdominal distension and characteristic TrP location; responds to TrP pressure release

Treatment

Trigger Point Injection

• Inject precisely at the TrP located at the angle of the twelfth rib, with a rib palpable beneath the finger
• Approach from the lateral or slightly posterior direction
• Do not direct the needle medially or deeply toward the intercostal space — the pleura lies medially and deeply in this region

Pressure Release

• Sustained firm pressure over the TrP at the twelfth rib angle
• Patient may self-administer while lying comfortably on the contralateral side
• Successful inactivation: belching should diminish or cease with sustained pressure and should not recur spontaneously

Corrective Actions

• Identify and treat any key TrPs in the paraspinal muscles at the T12 level and in the quadratus lumborum
• Abdominal (diaphragmatic) breathing
• Eliminate upper GI perpetuating factors (treat GORD if present; dietary modification as appropriate)
• Address any sustained twisted postural habits

Satellite Trigger Points

• External oblique — most likely muscle of origin; satellite relationship with paraspinal key TrPs
• Transversus abdominis — possible alternative muscle of origin via lumbodorsal fascia attachment
• Quadratus lumborum — likely key TrP at the T12–L1 level activating the belch button as satellite
• Paraspinal muscles T12 — key TrPs

Related Pages

• Muscle:External Oblique — Most likely muscle of origin
• Muscle:Transversus Abdominis — Alternative muscle of origin; lumbodorsal fascia attachment
• Pain:Belching — Diagnostic algorithm including the belch button TrP
• Pain:Epigastric — Belch button as myofascial source of upper GI symptoms

References

• Travell JG, Simons DG. Myofascial Pain and Dysfunction: The Trigger Point Manual, Volume 2: The Lower Extremities. Baltimore: Williams & Wilkins; 1992. Chapter 49.
• Alvarez WC. An Introduction to Gastro-enterology. Ed. 3. Paul B. Hoeber, New York, 1940 (p. 144).
• Gutstein RR. The role of abdominal fibrositis in functional indigestion. Miss Val Med J 66:114–24, 1944.