[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Anatomy](https://durgical.com/en/anatomy/) › [Spine](https://durgical.com/en/anatomy/region/spine/) › Transversus abdominis [Muscular system](https://durgical.com/en/anatomy/system/muscular-system/) · [Spine](https://durgical.com/en/anatomy/region/spine/) # Transversus abdominis The transversus abdominis is the deepest abdominal muscle, wrapping the belly like a corset; it helps stiffen the [spine](https://durgical.com/en/anatomy/region/spine/) before movement. Official name: Transversus abdominis muscle [See in 3D →](https://durgical.app/?from=durgipedia&lang=en#region=spine&select=transversus_abdominis&side=r) Opens in the Durgical app, no sign-up needed. ## What it is The deepest abdominal muscle, wrapping around the belly like a corset from the thoracolumbar fascia to the front midline. ## What it does Raises pressure inside the [abdomen](https://durgical.com/en/anatomy/region/abdomen/) and tightens the thoracolumbar fascia, helping stiffen the spine before you move. ## Key points - Deepest of the three flat muscles; its fibres run horizontally around the trunk - Its aponeurosis passes behind the [rectus abdominis](https://durgical.com/en/anatomy/rectus-abdominis-muscle/) above the arcuate line and in front of it below, where only transversalis fascia is left behind the muscle - The abdominal wall nerves run between it and the internal oblique: this neurovascular plane is the target of the TAP block ## Key facts **Origin** Inner surfaces of costal cartilages 7–12, thoracolumbar fascia, iliac crest, lateral third of [inguinal ligament](https://durgical.com/en/anatomy/inguinal-ligament/) **Insertion** [Linea alba](https://durgical.com/en/anatomy/linea-alba/) via aponeurosis; pubic crest and pecten pubis via conjoint tendon **Action** Compresses abdominal contents; raises intra-abdominal pressure; tenses the thoracolumbar fascia **Nerve** Thoracoabdominal nerves (T7–T11), subcostal (T12), iliohypogastric and ilioinguinal (L1) **Blood supply** Deep circumflex iliac, inferior epigastric, lower posterior intercostal and [lumbar arteries](https://durgical.com/en/anatomy/lumbar-arteries/) ## Relations **Superficial** [Internal oblique](https://durgical.com/en/anatomy/internal-abdominal-oblique-muscle/), with the lower thoracic, [iliohypogastric and ilioinguinal nerves](https://durgical.com/en/anatomy/iliohypogastric-nerve/) in the plane between them **Deep** [Transversalis fascia](https://durgical.com/en/anatomy/transversalis-fascia/), extraperitoneal fat and parietal [peritoneum](https://durgical.com/en/anatomy/peritoneum/); the deep inguinal ring lies in the transversalis fascia, lateral to the inferior [epigastric vessels](https://durgical.com/en/anatomy/inferior-epigastric-artery/) **Above** Its upper fibres interlock with the costal fibres of the [diaphragm](https://durgical.com/en/anatomy/diaphragm/) on the inner [costal cartilages](https://durgical.com/en/anatomy/costal-cartilage/) **Behind** Its aponeurosis joins the [thoracolumbar fascia](https://durgical.com/en/anatomy/thoracolumbar-fascia/) around [quadratus lumborum](https://durgical.com/en/anatomy/quadratus-lumborum-muscle/) and the erector spinae; it forms the floor of the superior lumbar triangle **Below** Its lowest fibres arch over the [inguinal canal](https://durgical.com/en/anatomy/inguinal-canal/) with the internal oblique and join it in the conjoint tendon ## How to find it It cannot be felt. On ultrasound of the flank it is the deepest of the three layers, just above the peritoneum; drawing the navel gently toward the spine (abdominal hollowing) makes it thicken and slide visibly. ## On imaging Ultrasound shows the three flat muscles of the flank as dark layers separated by bright fascia; transversus abdominis is the deepest, just above the peritoneum. The TAP block is placed in the plane between it and the internal oblique. Ultrasound or CT shows a Spigelian hernia passing through its aponeurosis at the linea semilunaris, often hidden under an intact [external oblique](https://durgical.com/en/anatomy/external-abdominal-oblique-muscle/) aponeurosis. ## Common problems - Delayed or weak activation is seen in some people with chronic low back pain. ## How it is diagnosed Exam; ultrasound can show its activation. ## Treatment - Core stability exercise programmes. ## Clinical notes - TAP block: under ultrasound, local anaesthetic placed between it and the internal oblique numbs the [skin](https://durgical.com/en/anatomy/skin/) and muscle of the anterior abdominal wall after surgery - Posterior component separation (transversus abdominis release) divides it to let the rectus abdominis move toward the midline in large hernia repairs - Spigelian hernias come through the aponeurosis along the linea semilunaris, usually near the arcuate line, often hidden under an intact external oblique ## Related conditions - [Inguinal hernia](https://durgical.com/en/conditions/inguinal-hernia/) - [Incisional (ventral) hernia](https://durgical.com/en/conditions/incisional-hernia/) ## Test yourself Think of the answer, then tap the question to see it. ## Which way do the fibres of the transversus abdominis run, and where does it lie among the flat muscles? Horizontally around the trunk; it is the deepest of the three flat abdominal muscles. ## Between which layers is a TAP block given in relation to the transversus abdominis? Between the transversus abdominis and the internal oblique, where the abdominal wall nerves run. ## How does the transversus abdominis aponeurosis change at the arcuate line? Above it the aponeurosis passes behind the rectus abdominis; below it, in front, leaving only transversalis fascia behind. ## What nerves supply the transversus abdominis? The thoracoabdominal nerves (T7–T11), the subcostal nerve (T12) and the iliohypogastric and ilioinguinal nerves (L1). [Add to my cards (4)](https://durgical.app/estudiar/?add=/en/anatomy/transversus-abdominis-muscle/) Educational information, not medical advice. For any symptom, see a health professional. ## Its names **Official Latin (TA2)** musculus transversus abdominis TA2 2375 **Official Spanish (DeCS)** Músculo transverso del abdomen DeCS D000009 **English (TA2)** Transversus abdominis muscle **Also called** transverse abdominal muscle ## Related - [Thoracolumbar fascia](https://durgical.com/en/anatomy/thoracolumbar-fascia/) - [Internal oblique](https://durgical.com/en/anatomy/internal-abdominal-oblique-muscle/) - [Intercostal nerves](https://durgical.com/en/anatomy/intercostal-nerves/) - [Iliohypogastric and ilioinguinal nerves](https://durgical.com/en/anatomy/iliohypogastric-nerve/) - [Hip bone](https://durgical.com/en/anatomy/hip-bone/) Sources: Terminologia Anatomica (TA2); [DeCS](https://decs.bvsalud.org/es/ths/resource/?id=30961); [Anatomy, Anterolateral Abdominal Wall Muscles](https://www.ncbi.nlm.nih.gov/books/NBK470334/). ## **Spotted a mistake?** We are always improving for the community. Tell us what is wrong and our team will review it. Report a mistake Representative model, for educational purposes only. --- Source: https://durgical.com/en/anatomy/transversus-abdominis-muscle/ License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/anatomy/transversus-abdominis-muscle/