Muscle:Transversus Abdominis: Difference between revisions

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'''External oblique''' is the most superficial of the three lateral abdominal wall muscles. Its trigger points (TrPs) produce a wide range of referred pain patterns — from "heartburn" in the epigastric region to groin and testicular pain — and can initiate viscerosomatic disturbances capable of closely mimicking appendicitis, cholecystitis, and other acute visceral pathology. Because its fibres interdigitate with the serratus anterior and latissimus dorsi, dysfunction in those muscles and in the thoracolumbar region can produce satellite TrPs in the external oblique and vice versa.
'''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 external oblique is the largest and most superficial of the lateral abdominal wall muscles. Its fibres run diagonally downward and forward from the external surfaces and inferior borders of the lower eight ribs. The lower three rib attachments interdigitate with the latissimus dorsi; the upper five interdigitate with the serratus anterior. Anteriorly the muscle joins the abdominal aponeurosis, attaching to the linea alba in the midline and to the anterior half of the iliac crest.
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:''' Increases intra-abdominal pressure (bilaterally); flexes and rotates the vertebral column — the external oblique rotates the vertebral column toward the contralateral side. Functions eccentrically to control and brake trunk rotation in the opposite direction.
'''Primary action:''' Tensing the linea alba.


'''Innervation:''' Branches of the eighth through twelfth intercostal nerves; segmental innervation T8–T12.
'''Innervation:''' Branch of the twelfth thoracic nerve.


'''Main synergists:''' Internal oblique (contralateral), serratus anterior, external intercostals, vertical costal fibres of latissimus dorsi.
'''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


'''Memory aid for fibre direction:''' Place the right hand flat on the lower left abdomen with fingers pointing downward toward the opposite hip — the fingers represent the external oblique fibre direction on that side (same as sliding hands into the front trouser pockets).
==Referred Pain Pattern==


==Referred Pain Patterns==
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.


The external oblique TrPs have multiple referred pain patterns that may reach into the chest, travel straight or diagonally across the abdomen, and extend downward. Variability in patterns likely represents the successively deeper layers of this muscle and the diagonal crisscross arrangement of its fibres, analogous to the plies of a tyre.
==Somatovisceral Effects==


===Upper Attachment TrPs — "Heartburn"===
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.
 
Active TrPs in the upper external oblique, in the part of the muscle overlying the anterior rib cage, are likely to produce '''deep epigastric pain''' described by the patient as "heartburn." This pain pattern may occasionally extend to other parts of the abdomen. These are sometimes called '''costal''' or '''subcostal''' TrPs. The same patterns have been observed from TrPs in the external oblique at its rib cage attachments and from TrPs in the pectoralis major, which overlies this region.
 
===Lower Lateral Wall TrPs — Groin and Testicular Pain===
 
Active TrPs in the lower lateral abdominal wall — possibly in any one of the three muscle layers — refer pain to:
* The '''groin''' and '''testicle''' (or labium majus in females)
* Other parts of the lower abdomen
 
Experimental injection of hypertonic saline into the external obliques near the anterior superior iliac spine induced referred pain over the lower portion of that quadrant of the abdomen, along the inguinal ligament and into the testicle. A left external abdominal oblique TrP in a 10-year-old child referred severe pain from the left upper quadrant to the left inguinal region.
 
TrPs along the upper rim of the pubis and the lateral half of the inguinal ligament may lie in the lower internal oblique or in the lower rectus abdominis; when needled, such TrPs often refer pain to the urinary bladder region.
 
===The "Belch Button" TrP===
 
The '''belch button''' is an uncommon but clinically important TrP. It has not been consistently localised to a specific muscle — it may lie in the posterior fringe of the external oblique, or it may be a fascial TrP in the lumbodorsal fascia. It is found at, or just below, the angle of the twelfth rib. When located by palpation, a rib is palpable beneath the examining finger.
 
When sufficiently active, this TrP causes spontaneous belching and, in severe cases, projectile vomiting — a serious postoperative complication risk. The patient is likely to complain of a "stomach problem" with much belching of gas. See [[Muscle:Belch_Button]] for full details.
 
==Somatovisceral and Viscerosomatic Effects==
 
TrPs in the external oblique participate in strong reciprocal somatovisceral and viscerosomatic interactions:
* '''Somatovisceral:''' Active TrPs can initiate or worsen diarrhoea, nausea, vomiting, urinary bladder irritability, and sphincter spasm — without any underlying visceral pathology
* '''Viscerosomatic:''' Visceral disease (peptic ulcer, intestinal parasites, dysentery, ulcerative colitis, diverticulitis, cholelithiasis) can activate and perpetuate TrPs in the external oblique, which may then persist long after the initiating visceral disease has resolved, continuing to refer pain that closely mimics the original visceral symptom
 
A direct linear correlation has been demonstrated between the severity of visceral pain episodes and hyperalgesia of the ipsilateral external oblique muscle.


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


===Visceral Disease===
===Surgery===
Peptic ulcer, intestinal parasites (''Entamoeba histolytica'', fish or beef tapeworm), dysentery, ulcerative colitis, diverticulosis, diverticulitis, and cholelithiasis are important activating factors.
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.


===Trauma and Surgery===
===Pelvic Visceral Disease===
Acute trauma, direct blow, or abdominal scar (appendicectomy, hysterectomy) — the initiating stresses during surgery include excessive stretch by retractors and associated ischaemia.
The same viscerosomatic cycle as for other abdominal muscles — pelvic visceral disease activates TrPs which may persist after the primary disease has resolved.


===Occupational and Postural Strain===
===Related TrP Activity===
* Sustained twisted posture — sitting sideways at a desk due to monitor placement
TrP activity in the lower rectus abdominis — the pyramidalis' primary functional neighbour — likely activates pyramidalis TrPs as satellites.
* Activities requiring vigorous twisting body motion (throwing the discus)
* Forward-head posture or slumped sitting posture — see [[Concept:Postural_Considerations]]
 
===Other Factors===
* Paradoxical respiration — asynchronous chest-diaphragm breathing patterns
* Over-enthusiastic or poorly conditioned abdominal exercise
* Emotional stress, cold exposure, constipation (straining at stool)
* '''Satellite TrP activation''' — paraspinal TrPs at T7–T12 levels may activate external oblique TrPs as satellites; dorsal TrPs at the belch button location may be key TrPs activating the external oblique


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


===Abdominal Tension Test===
The pyramidalis lies within the anterior rectus sheath just above the symphysis pubis and is palpated by flat palpation in the suprapubic region:
 
The Abdominal Tension Test distinguishes abdominal wall TrP pain from pain originating inside the abdomen, and is essential whenever abdominal TrPs are suspected:
# With the supine patient at rest, compress the sensitive area with sufficient pressure to cause steady pain
# Ask the patient to raise both heels several inches off the table — this tenses the abdominal muscles and lifts the palpating finger away from the viscera
# '''If the pain increases:''' the pain originates in the abdominal wall
# '''If the pain decreases:''' the pain more likely originates inside the abdomen
 
Modified techniques to increase abdominal tension include a partial sit-up (Llewellyn and Jones), the Carnett technique (patient crosses arms and sits half-way forward), raising only the head and shoulders (Wilson / Kelsey), or elevating both feet and head simultaneously (de Valera and Raftery).
 
===Trigger Point Examination===
 
The patient lies supine and takes a deep diaphragmatic breath, holding it to passively stretch and relax the abdominal muscles and increase sensitivity to palpation.


'''Attachment TrPs:''' Palpate along the lower border of the rib cage and along the line of attachment to the iliac crest using flat palpation.
* 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


'''Central TrPs:''' The patient lies on the contralateral side and takes a similar deep lateral breath. In thin patients, flex the hips to slacken the abdominal wall; the lateral wall can then be grasped between the fingers and thumb in a '''pincer grip'''. Roll the muscle between digits to identify tender nodules in palpable bands.
The [[Muscle:External_Oblique#Abdominal_Tension_Test|Abdominal Tension Test]] is performed as described for all abdominal muscles.


'''Umbilical deviation test:''' At rest, the umbilicus deviates away from a weaker (inhibited) muscle and toward a stronger (hyperactive) one. Deviation may also become apparent during activities such as laughing, coughing, or raising one leg from the bed.
'''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
|-
|-
| Appendicitis || Right lower quadrant pain from lower external oblique TrPs mimics appendicitis; abdominal wall shows palpable taut band and nodule rather than board-like diffuse rigidity; Abdominal Tension Test positive; ESR and WBC normal; Rovsing's sign and rebound tenderness absent
| 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
|-
| Cholecystitis || Right upper quadrant TrPs in the costal portion of the external oblique confused with gallbladder pain; ultrasound and liver function tests distinguish; subcutaneous infiltration of the painful area with procaine relieves TrP-generated pain
|-
|-
| Inguinal hernia || Lower lateral TrP pain radiating into the groin along the inguinal ligament; no palpable hernia sac; Valsalva does not reproduce pain
| 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
|-
|-
| Testicular or ovarian pathology || TrPs in lower lateral abdominal wall refer pain to testicle or labium — ultrasound required to exclude primary pathology
| Cystitis / urethritis || Midline suprapubic TrP pain mimics bladder pain; urinalysis and culture differentiate
|-
|-
| Peptic ulcer || Upper external oblique TrPs produce epigastric "heartburn"; upper GI series and endoscopy differentiate; TrP injection or pressure release reproduces and relieves the pain
| Gynaecological pathology || Central lower abdominal TrP pain may mimic dysmenorrhoea, endometriosis, or ovarian pathology — gynaecological examination and pelvic ultrasound differentiate
|-
|-
| Fibromyalgia || Widespread pain present for ≥3 months; fibromyalgia and TrPs are different diseases that cause pain for different reasons and respond to different treatments; more than half of fibromyalgia patients also have TrPs
| 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 — Spray and Stretch===
* Patient supine with the hip joint at the edge of the treatment table; lower limbs extend over the end; one limb supported on a stool to avoid lumbosacral overextension; arms raised overhead
* Vapocoolant spray applied in sweeps in a '''caudal direction''' (down-sweep pattern) over the abdomen and extending to the iliopsoas attachment
* Patient takes a very deep breath, allowing the diaphragm to strongly protrude the relaxed abdominal musculature — this is the critical stretch step
* The contralateral muscles must also be treated
* After release, patient assumes bilateral knee-to-chest position; moist heat applied promptly
Postisometric relaxation and contract-relax techniques are also effective for central TrPs. Pressure release (ischaemic compression) is most successful for TrPs close to the pubic arch; less successful in patients with excess adipose tissue.


===Trigger Point Injection===
===Trigger Point Injection===


Injection of lateral wall oblique TrPs employs the '''pincer technique''':
* The needle is directed '''cephalad, close to the midline, away from the pubis''' — rather than toward the bone
# Flex the patient's hips to slacken the abdominal wall
* 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
# Grasp the abdominal wall between the fingers and thumb so that no abdominal contents remain within the grasp
* Injection proceeds as for other suprapubic attachment TrPs
# Locate the TrP by rolling the musculature between the digits to identify a tender nodule in a palpable band
# Direct the needle precisely into the TrP fixed within the operator's grasp
# Avoid penetrating the peritoneal cavity


Active full range of motion with repetition of vapocoolant spray is performed slowly after injection, then followed by moist heat.
===Corrective Actions===


===Corrective Actions===
* Direct pressure release on the suprapubic TrP, pressing toward the pubic arch; self-administration is valuable between menstrual periods
* Self-administration of TrP pressure release
* Abdominal (diaphragmatic) breathing — the most effective active stretch exercise for lateral abdominal muscles, especially when performed prone
* Pelvic-tilt exercise (see [[Muscle:Rectus_Abdominis#Corrective_Actions_and_Exercises|Muscle:Rectus Abdominis — Corrective Actions]])
* Pelvic-tilt exercise (see [[Muscle:Rectus_Abdominis#Corrective_Actions_and_Exercises|Muscle:Rectus Abdominis — Corrective Actions]])
* Sit-back/Abdominal-curl/Sit-up exercise sequence (see [[Muscle:Rectus_Abdominis#Corrective_Actions_and_Exercises|Muscle:Rectus Abdominis — Corrective Actions]])
* Abdominal (diaphragmatic) breathing
* Laughter — a vigorous isometric exercise for all abdominal muscles; "pleasant medicine"
* 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:Internal_Oblique|Internal oblique]] — primary functional partner; commonly co-active
* [[Muscle:Rectus_Abdominis|Rectus abdominis]] — primary functional partner; lower rectus TrPs commonly co-active
* [[Muscle:Transversus_Abdominis|Transversus abdominis]] — deep synergist; commonly co-active
* 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
* Latissimus dorsi — interdigitates at lower rib attachments; bilateral satellite relationship
* Serratus anterior — interdigitates at upper rib attachments
* Paraspinal muscles T7–T12 — key TrPs that activate external oblique as satellite
* Iliopsoas — lower external oblique stretch also stretches iliopsoas; commonly co-active TrPs


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


* [[Pain:Front-of-Chest]] — Upper external oblique listed in Ch. 41 Pain Guide under front-of-chest pain
* [[Pain:Abdominal]] — Diagnostic algorithm
* [[Pain:Abdominal]] — Diagnostic algorithm
* [[Pain:Right_Upper_Quadrant]] — External oblique as source of pseudo-cholecystitis
* [[Pain:Suprapubic]] — Pyramidalis and lower rectus as myofascial sources
* [[Pain:Groin_and_Testicle]] — Lower lateral wall referral pattern
* [[Pain:Dysmenorrhoea]] — Lower rectus and pyramidalis TrPs
* [[Muscle:Internal_Oblique]] — Primary functional partner
* [[Muscle:Rectus_Abdominis]] — Primary functional partner
* [[Muscle:Transversus_Abdominis]] — Deep synergist
* [[Muscle:Internal_Oblique]] — Conjoined tendon partner at pubic arch
* [[Muscle:Rectus_Abdominis]] — Medial synergist; corrective exercises shared
* [[Muscle:Belch_Button]] — Belch button TrP full description
* [[Concept:Postural_Considerations]]


==References==
==References==
Line 159: Line 96:
* 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: 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).
* 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:Vol1 Ch49]]
[[Category:Vol1 Ch49]]
[[Category:Torso Pain]]
[[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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