Muscle:Transversus Abdominis: Difference between revisions

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Created page with "'''Transversus abdominis''' is the deepest of the three lateral abdominal wall muscles. Its TrPs produce referred pain in a horizontal band across the upper abdomen with concentration at the xiphoid process, and are associated with enthesitis along the inferior costal margin that is characteristically aggravated by coughing. The transversus abdominis is the first of all the abdominal wall muscles to be activated in anticipation of lower limb movement — a feedforward re..."
 
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'''Transversus abdominis''' is the deepest of the three lateral abdominal wall muscles. Its TrPs produce referred pain in a horizontal band across the upper abdomen with concentration at the xiphoid process, and are associated with enthesitis along the inferior costal margin that is characteristically aggravated by coughing. The transversus abdominis is the first of all the abdominal wall muscles to be activated in anticipation of lower limb movement — a feedforward response that underlies its primary role in dynamic spinal stabilisation. The "belch button" TrP is closely associated with this muscle or the adjacent lumbodorsal fascia.
'''Pyramidalis''' is a small, variable, triangular muscle located within the anterior rectus sheath, just above the symphysis pubis. Its TrP refers pain close to the midline between the symphysis pubis and the umbilicus. The pyramidalis is absent bilaterally in approximately 17–20% of individuals and is absent unilaterally more commonly than bilaterally — its presence should never be assumed. It lies entirely within the anterior rectus sheath, and its TrP is closely associated with lower rectus abdominis TrPs and with pelvic floor dysfunction.


==Anatomy==
==Anatomy==


The transversus abdominis fibres run nearly horizontally around the abdomen. They attach anteriorly to the midline linea alba via the rectus sheath, which surrounds the rectus abdominis above the arcuate line, and attach to the pubis through the conjoined tendon (formed with the internal oblique) below that line. Laterally the transversus attaches to the lateral one-third of the inguinal ligament, to the anterior three-quarters of the iliac crest, to the thoracolumbar fascia, and to the inner surfaces of the cartilages of the last six ribs, where its fibres interdigitate with those of the diaphragm.
The pyramidalis attaches '''below''' to the anterior surface of the ramus of the pubis and '''above''' to the linea alba approximately mid-way between the symphysis pubis and the umbilicus. It lies entirely within the anterior rectus sheath.


'''Primary action:''' Contraction increases intra-abdominal pressure. The transversus abdominis is the first abdominal muscle activated in anticipation of lower limb movements — a feedforward activation independent of movement direction, linked to the control of spinal stability against perturbations.
'''Primary action:''' Tensing the linea alba.


'''Innervation:''' Branches of the eighth through twelfth intercostal nerves; branches of the iliohypogastric and ilioinguinal nerves; additionally by the seventh intercostal nerve. Segmental innervation T7–L1.
'''Innervation:''' Branch of the twelfth thoracic nerve.


==Referred Pain Patterns==
'''Frequency of absence:'''
* Absent bilaterally in approximately 3.3% of Japanese subjects
* Absent bilaterally in approximately 25% of Scottish subjects
* Absent bilaterally in 15–20% of bodies in general population studies
* In a study of 430 sides, absent in 17.7%
* Unilateral absence is more common than bilateral absence


===Craniad Fibres — Upper Abdominal Band===
==Referred Pain Pattern==


Active TrPs in the more cranial (upper) portion of the transversus abdominis refer pain as a '''band across the upper abdomen between the anterior costal margins'''. The distressing pain sometimes concentrates on the region of the '''xiphoid process'''.
The pyramidalis refers pain close to the '''midline between the symphysis pubis and the umbilicus''' — a central lower abdominal pain that may be confused with pain from the lower rectus abdominis or from pelvic visceral structures. The pain is strictly midline and suprapubic, which helps distinguish it from lower rectus abdominis TrP pain which tends to be slightly more lateral and located above the pubic attachment.


===Costal Attachment — Inferior Costal Margin Pain and Enthesitis===
==Somatovisceral Effects==


TrPs in the transversus fibres attaching to the lower costal cartilage are likely to cause '''marked enthesitis along the inferior costal margin'''. This becomes very distressing when coughing. Continued coughing is a potent perpetuating factor once the enthesitis is established.
A TrP just above the pubis may cause spasm of the detrusor and urinary sphincter muscles. Given the pyramidalis' intimate anatomical relationship with the lower rectus abdominis TrPs and pelvic floor, these somatovisceral effects are difficult to attribute to the pyramidalis in isolation — they are more reliably attributed to the closely associated lower rectus abdominis.
 
===The "Belch Button" TrP===
 
The belch button may represent a transversus abdominis attachment TrP at the region of the twelfth rib angle, where the transversus attaches to the thoracolumbar fascia, or it may be a fascial TrP in the lumbodorsal fascia itself. When located by palpation, a rib is palpable beneath the examining finger. When sufficiently active it causes spontaneous belching and, in severe cases, projectile vomiting. See [[Muscle:Abdominal_Wall/Belch_Button|Muscle:Abdominal Wall/Belch Button]] for full clinical details.
 
==Somatovisceral and Viscerosomatic Effects==
 
The transversus abdominis participates in the same pattern of somatovisceral and viscerosomatic interactions as the other lateral abdominal wall muscles. Particular associations include:
* Belching and projectile vomiting (belch button TrP)
* Upper abdominal distress and bloating (upper fibre TrPs)
* Inferior costal margin pain aggravated by coughing (costal attachment enthesitis)
 
Visceral disease can activate and perpetuate transversus TrPs, which may persist after the initiating visceral disease has resolved.


==Activation and Perpetuating Factors==
==Activation and Perpetuating Factors==


===Visceral Disease===
===Surgery===
Same as for the external and internal oblique.
Lower abdominal and pelvic surgery (caesarean section, hysterectomy, prostatectomy, appendicectomy) places the pyramidalis directly in the surgical field; TrP activation from retractor stretch and ischaemia is probable.


===Respiratory===
===Pelvic Visceral Disease===
* Continued coughing — the most important perpetuating factor for costal attachment enthesitis
The same viscerosomatic cycle as for other abdominal muscles — pelvic visceral disease activates TrPs which may persist after the primary disease has resolved.
* Paradoxical respiration — compromises the feedforward stabilisation function of the transversus


===Mechanical and Other===
===Related TrP Activity===
* Acute trauma and abdominal surgery
TrP activity in the lower rectus abdominis — the pyramidalis' primary functional neighbour — likely activates pyramidalis TrPs as satellites.
* Sustained postures that compress the abdominal wall (tight belt or girdle)
* Over-enthusiastic abdominal exercise
* Emotional stress


==Clinical Examination==
==Clinical Examination==


The transversus abdominis is the deepest lateral wall muscle and its central TrPs are not reliably accessible to palpation for most examiners. Access relies on:
The pyramidalis lies within the anterior rectus sheath just above the symphysis pubis and is palpated by flat palpation in the suprapubic region:


* '''Pincer palpation''' of the lateral abdominal wall (as for the internal oblique) for lateral central TrPs
* The examiner presses down '''against the upper edge of the pubic arch''' — not on the flat anterior surface of the pubis
* '''External flat palpation along the inferior costal margin''' for costal attachment TrPs — the needle is always directed at the caudal border of the rib, never deep to it, to avoid pleural puncture
* These TrPs feel like small buttons or short bands at the region of attachment
* '''Belch button palpation:''' flat palpation at the angle of the twelfth rib; a rib is palpable beneath the finger; pressure may provoke belching, confirming the diagnosis
* The midline location distinguishes pyramidalis TrPs from the slightly more lateral lower rectus abdominis attachment TrPs


The [[Muscle:External_Oblique#Abdominal_Tension_Test|Abdominal Tension Test]] is performed as described for all abdominal muscles.
The [[Muscle:External_Oblique#Abdominal_Tension_Test|Abdominal Tension Test]] is performed as described for all abdominal muscles.
'''Note for injection:''' Distinguish the pyramidalis TrP from the lower rectus abdominis attachment TrP by the strictly midline location and by the direction of needle injection — for the pyramidalis the needle is directed cephalad (away from the bone, toward the umbilicus), whereas for the lower rectus abdominis pubic attachment the needle is directed toward the pubic bone.


==Differential Diagnosis==
==Differential Diagnosis==
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! Condition !! Distinguishing features
! Condition !! Distinguishing features
|-
|-
| Xiphoidalgia / xiphoid syndrome || TrPs in upper transversus refer pain to xiphoid process mimicking xiphoidalgia; distinguished by TrP examination and reproduction of pain on direct pressure
| Lower rectus abdominis TrP || Pyramidalis TrP is strictly midline and suprapubic; lower rectus TrPs are located above the pubic attachment and slightly more lateral; both may coexist and are treated separately
|-
|-
| Tietze's syndrome / costochondritis || Costal attachment enthesitis from transversus TrPs may be clinically indistinguishable from Tietze's syndrome; Tietze's typically involves visible and palpable swelling at the costo-sternal junction; TrP injection to the costal attachment may resolve both
| Symphysis pubis dysfunction || Symphysis pubis pain reproduced by compression or distraction; pyramidalis TrP pain reproduced by direct TrP palpation; imaging may show symphysis changes in true symphysis pubis dysfunction
|-
|-
| Hiatal hernia / GORD || Upper transversus TrPs producing epigastric band pain and bloating can mimic hiatal hernia; endoscopy and pH monitoring differentiate
| Cystitis / urethritis || Midline suprapubic TrP pain mimics bladder pain; urinalysis and culture differentiate
|-
|-
| Slipping rib syndrome || Inferior costal enthesitis from transversus attachment TrPs contributes to presentations of slipping rib or rib-tip syndrome; the chondral intercostal muscles, pectoralis major, and transversus abdominis are likely candidates for the central TrPs causing the enthesitis
| Gynaecological pathology || Central lower abdominal TrP pain may mimic dysmenorrhoea, endometriosis, or ovarian pathology — gynaecological examination and pelvic ultrasound differentiate
|-
|-
| Pleurisy || Inferior costal margin pain aggravated by breathing; distinguished by respiratory examination, chest auscultation, and CXR
| Detrusor instability || TrP just above the pubis may cause detrusor and sphincter spasm; distinguishing from primary detrusor instability may require urodynamic studies; TrP inactivation resolves symptoms in the myofascial case
|}
|}


==Treatment==
==Treatment==


===Trigger Point Release===
===Trigger Point Injection===
 
Treatment principles are the same as for the external and internal oblique. Injection of '''costal attachment TrPs''' along the costal margin requires special care:
* The transversus attaches to the underside of the costal margin, where the fibres interdigitate with the diaphragm — beyond which lies the pleura
* The exact position of the needle tip is established by gently contacting the costal cartilage and walking the needle caudally from there
* The needle is directed at the '''caudal border of the rib, not deep to it'''


Central TrPs are injected using the pincer technique (see [[Muscle:External_Oblique#Trigger_Point_Injection|Muscle:External Oblique — Injection]]).
* The needle is directed '''cephalad, close to the midline, away from the pubis''' — rather than toward the bone
* This direction injects the pyramidalis muscle and distinguishes it from the lower rectus abdominis pubic attachment injection, where the needle is directed toward the pubic bone
* Injection proceeds as for other suprapubic attachment TrPs


===Corrective Actions===
===Corrective Actions===


'''Abdominal (diaphragmatic) breathing''' is a primary corrective exercise — it actively stretches all lateral wall muscles and is the most effective active stretch for the transversus abdominis. Especially effective when performed in the prone position.
* Direct pressure release on the suprapubic TrP, pressing toward the pubic arch; self-administration is valuable between menstrual periods
 
* Pelvic-tilt exercise (see [[Muscle:Rectus_Abdominis#Corrective_Actions_and_Exercises|Muscle:Rectus Abdominis — Corrective Actions]])
Selective activation of the transversus abdominis (drawing-in manoeuvre) is fundamental to spinal stabilisation programmes and is appropriate corrective exercise for this muscle when TrPs have been successfully inactivated.
* Abdominal (diaphragmatic) breathing
* Sit-back/Abdominal-curl exercise sequence when pain-free (see [[Muscle:Rectus_Abdominis#Corrective_Actions_and_Exercises|Muscle:Rectus Abdominis — Corrective Actions]])


==Satellite Trigger Points==
==Satellite Trigger Points==


* [[Muscle:External_Oblique|External oblique]] — outer synergist
* [[Muscle:Rectus_Abdominis|Rectus abdominis]] — primary functional partner; lower rectus TrPs commonly co-active
* [[Muscle:Internal_Oblique|Internal oblique]] — middle synergist; forms conjoined tendon
* Pelvic floor muscles — close anatomical relationship; commonly co-active in pelvic pain syndromes
* [[Muscle:Rectus_Abdominis|Rectus abdominis]] — medial synergist
* [[Muscle:Internal_Oblique|Internal oblique]] — conjoined tendon relationship at pubic arch
* Diaphragm — interdigitates at costal attachments; primary functional partner for respiration
* Quadratus lumborum — posterior functional unit; thoracolumbar fascia attachment shared


==Related Pages==
==Related Pages==


* [[Pain:Epigastric|Pain:Epigastric]] — Upper transversus band referral pattern
* [[Pain:Abdominal]] — Diagnostic algorithm
* [[Pain:Abdominal|Pain:Abdominal]] — Diagnostic algorithm
* [[Pain:Suprapubic]] — Pyramidalis and lower rectus as myofascial sources
* [[Muscle:External_Oblique|Muscle:External Oblique]] — Outer synergist
* [[Pain:Dysmenorrhoea]] — Lower rectus and pyramidalis TrPs
* [[Muscle:Internal_Oblique|Muscle:Internal Oblique]] — Middle synergist
* [[Muscle:Rectus_Abdominis]] — Primary functional partner
* [[Muscle:Rectus_Abdominis|Muscle:Rectus Abdominis]] — Medial synergist
* [[Muscle:Internal_Oblique]] — Conjoined tendon partner at pubic arch
* [[Muscle:Abdominal_Wall/Belch_Button|Muscle:Abdominal Wall/Belch Button]] — Belch button TrP full description


==References==
==References==


* Travell JG, Simons DG. ''Myofascial Pain and Dysfunction: The Trigger Point Manual, Volume 2: The Lower Extremities''. Baltimore: Williams & Wilkins; 1992. Chapter 49.
* 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 49 (pp. 940–970).
* Travell JG, Simons DG. ''Myofascial Pain and Dysfunction: The Trigger Point Manual, Volume 1''. 2nd ed. Chapter 41 (pp. 801–818).
* Beaton LE, Anson BJ. The pyramidalis muscle: its occurrence and size in American white and negroes. ''Am J Phys Anthropol'' 25:261–269, 1939.
* Anson BJ, Beaton LE, McVay CB. The pyramidalis muscle. ''Anatomical Record'' 72:405–411, 1938.


[[Category:Muscle]]
[[Category:Muscle]]
[[Category:Vol2_Ch49]]
[[Category:Vol1 Ch49]]
[[Category:Torso]]
[[Category:Torso Pain]]

Latest revision as of 19:26, 28 May 2026

Pyramidalis is a small, variable, triangular muscle located within the anterior rectus sheath, just above the symphysis pubis. Its TrP refers pain close to the midline between the symphysis pubis and the umbilicus. The pyramidalis is absent bilaterally in approximately 17–20% of individuals and is absent unilaterally more commonly than bilaterally — its presence should never be assumed. It lies entirely within the anterior rectus sheath, and its TrP is closely associated with lower rectus abdominis TrPs and with pelvic floor dysfunction.

Anatomy

The pyramidalis attaches below to the anterior surface of the ramus of the pubis and above to the linea alba approximately mid-way between the symphysis pubis and the umbilicus. It lies entirely within the anterior rectus sheath.

Primary action: Tensing the linea alba.

Innervation: Branch of the twelfth thoracic nerve.

Frequency of absence:

  • Absent bilaterally in approximately 3.3% of Japanese subjects
  • Absent bilaterally in approximately 25% of Scottish subjects
  • Absent bilaterally in 15–20% of bodies in general population studies
  • In a study of 430 sides, absent in 17.7%
  • Unilateral absence is more common than bilateral absence

Referred Pain Pattern

The pyramidalis refers pain close to the midline between the symphysis pubis and the umbilicus — a central lower abdominal pain that may be confused with pain from the lower rectus abdominis or from pelvic visceral structures. The pain is strictly midline and suprapubic, which helps distinguish it from lower rectus abdominis TrP pain which tends to be slightly more lateral and located above the pubic attachment.

Somatovisceral Effects

A TrP just above the pubis may cause spasm of the detrusor and urinary sphincter muscles. Given the pyramidalis' intimate anatomical relationship with the lower rectus abdominis TrPs and pelvic floor, these somatovisceral effects are difficult to attribute to the pyramidalis in isolation — they are more reliably attributed to the closely associated lower rectus abdominis.

Activation and Perpetuating Factors

Surgery

Lower abdominal and pelvic surgery (caesarean section, hysterectomy, prostatectomy, appendicectomy) places the pyramidalis directly in the surgical field; TrP activation from retractor stretch and ischaemia is probable.

Pelvic Visceral Disease

The same viscerosomatic cycle as for other abdominal muscles — pelvic visceral disease activates TrPs which may persist after the primary disease has resolved.

TrP activity in the lower rectus abdominis — the pyramidalis' primary functional neighbour — likely activates pyramidalis TrPs as satellites.

Clinical Examination

The pyramidalis lies within the anterior rectus sheath just above the symphysis pubis and is palpated by flat palpation in the suprapubic region:

  • The examiner presses down against the upper edge of the pubic arch — not on the flat anterior surface of the pubis
  • These TrPs feel like small buttons or short bands at the region of attachment
  • The midline location distinguishes pyramidalis TrPs from the slightly more lateral lower rectus abdominis attachment TrPs

The Abdominal Tension Test is performed as described for all abdominal muscles.

Note for injection: Distinguish the pyramidalis TrP from the lower rectus abdominis attachment TrP by the strictly midline location and by the direction of needle injection — for the pyramidalis the needle is directed cephalad (away from the bone, toward the umbilicus), whereas for the lower rectus abdominis pubic attachment the needle is directed toward the pubic bone.

Differential Diagnosis

Condition Distinguishing features
Lower rectus abdominis TrP Pyramidalis TrP is strictly midline and suprapubic; lower rectus TrPs are located above the pubic attachment and slightly more lateral; both may coexist and are treated separately
Symphysis pubis dysfunction Symphysis pubis pain reproduced by compression or distraction; pyramidalis TrP pain reproduced by direct TrP palpation; imaging may show symphysis changes in true symphysis pubis dysfunction
Cystitis / urethritis Midline suprapubic TrP pain mimics bladder pain; urinalysis and culture differentiate
Gynaecological pathology Central lower abdominal TrP pain may mimic dysmenorrhoea, endometriosis, or ovarian pathology — gynaecological examination and pelvic ultrasound differentiate
Detrusor instability TrP just above the pubis may cause detrusor and sphincter spasm; distinguishing from primary detrusor instability may require urodynamic studies; TrP inactivation resolves symptoms in the myofascial case

Treatment

Trigger Point Injection

  • The needle is directed cephalad, close to the midline, away from the pubis — rather than toward the bone
  • This direction injects the pyramidalis muscle and distinguishes it from the lower rectus abdominis pubic attachment injection, where the needle is directed toward the pubic bone
  • Injection proceeds as for other suprapubic attachment TrPs

Corrective Actions

Satellite Trigger Points

  • Rectus abdominis — primary functional partner; lower rectus TrPs commonly co-active
  • Pelvic floor muscles — close anatomical relationship; commonly co-active in pelvic pain syndromes
  • Internal oblique — conjoined tendon relationship at pubic arch

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 49 (pp. 940–970).
  • Travell JG, Simons DG. Myofascial Pain and Dysfunction: The Trigger Point Manual, Volume 1. 2nd ed. Chapter 41 (pp. 801–818).
  • Beaton LE, Anson BJ. The pyramidalis muscle: its occurrence and size in American white and negroes. Am J Phys Anthropol 25:261–269, 1939.
  • Anson BJ, Beaton LE, McVay CB. The pyramidalis muscle. Anatomical Record 72:405–411, 1938.
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