GENERAL INFORMATION
The abdomen is a region of the body located between the thorax (chest) as well as the pelvis. It contains various organs, including the stomach, liver, intestines, kidneys, as well as reproductive organs. Additionally, the abdomen is surrounded by several layers of muscles, including the transversus abdominis.
TRANSVERSUS ABDOMINIS
The transversus abdominis is a flat muscle located in the anterior (front) abdominal wall. It is the deepest of the abdominal muscles and plays a vital role in stabilising the core as well as maintaining posture.
ORIGIN
The transversus abdominis originates from the following structures:
- The inner surfaces of the lower six ribs
- Lumbar fascia: A sheet of connective tissue on the lower back
- Iliac crest: The upper edge of the hip bone
INSERTION POINT
The muscle inserts into the following structures:
- Linea alba: A fibrous structure that runs vertically down the midline of the abdomen
- Pubic crest: A ridge of bone located on the front side of the pubic bone
MAJOR ARTERIES
The transversus abdominis receives its blood supply from branches of the following arteries:
- Inferior epigastric artery
- Deep circumflex iliac artery
- Lumbar arteries
NEURAL INNERVATION
The muscle is innervated by the lower intercostal nerves (T7-T12) as well as the subcostal nerve (T12).
TRIGGER POINT
The transversus abdominis can develop trigger points, which are localised areas of muscle tightness and tenderness. These trigger points may refer to pain in the lower abdomen, lower back, as well as pelvis.
CONCENTRIC FUNCTION
The concentric function of the transversus abdominis involves the contraction of the muscle fibres. It also results in the compression of the abdominal contents. Also, this contraction helps increase intra-abdominal pressure.
ECCENTRIC FUNCTION
The eccentric function of the transversus abdominis refers to the controlled lengthening of the muscle fibres. Consequently, it assists in trunk flexion and rotation by resisting excessive forward movement as well as rotation of the trunk.
ISOMETRIC FUNCTION
The isometric function of this muscle involves maintaining a static contraction without any change in muscle length. This function helps stabilise the trunk as well as maintain core stability.
RELATED MUSCLES (SCIENTIFIC NAMES)
- Rectus abdominis: Runs vertically on the front of the abdomen, crucial for flexing the spine and maintaining posture.
- Internal oblique: Assists in trunk rotation and lateral flexion, providing deeper support for the abdomen and stabilising the core.
- External oblique: Located on the sides and front of the abdomen, it is important for trunk rotation and lateral flexion and contributes to the overall stability and mobility of the torso.
ANTAGONIST MUSCLES
- Erector spinae muscles (iliocostalis, longissimus, spinalis): Extend and rotate the spine, opposing the flexion action of the transversus abdominis. It is also essential for maintaining an upright posture.
- Quadratus lumborum: Stabilises and laterally flexes the spine, countering the core stability provided by the transversus abdominis, which is crucial for lower back support.
- Gluteus maximus: Extends and externally rotates the hip, opposing the transversus abdominis in hip flexion and core stability, playing a key role in movement and posture.
COMMON INJURIES
- Diastasis recti: A separation of the abdominal muscles, often occurring during pregnancy due to excessive abdominal pressure, leading to a visible bulge and potential weakness in the core.
- Strains or tears: Result from overstretching or excessive force, leading to pain, inflammation, and limited movement, common in high-intensity activities or improper lifting techniques.
- Abdominal hernias: A protrusion of abdominal organs through a weakened area in the abdominal wall, causing discomfort and a visible bulge and requiring medical attention to prevent complications.
EXERCISES
- Abdominal hollowing or drawing-in exercises: Engage the transversus abdominis by pulling the belly button towards the spine. By improving core strength and stability, they are often used in Pilates and physical therapy.
- Planks and side planks: Hold a plank position to engage the core muscles, enhancing stability and endurance, with side planks targeting the obliques and transversus abdominis.
- Deadbugs: Lie on your back, lift opposite arm and leg, and alternate, targeting core stability and coordination, reducing the risk of lower back pain.
- Bird dogs: On hands and knees, extend opposite arm and leg, maintaining a stable core to strengthen the transversus abdominis, improving balance and overall core strength.
- Pallof presses: Stand with a resistance band press outwards while maintaining a stable core, resisting rotation to strengthen the transversus abdominis, enhancing anti-rotational strength.
STRETCHES
- Child’s pose: Sit back on your heels with arms extended forward, stretching the lower back and core muscles, promoting relaxation and flexibility.
- Cat-camel stretch: On hands and knees, alternate between arching and rounding the back, improving flexibility in the spine and abdominal muscles and enhancing spinal mobility.
- Supine twist: Lie on your back, cross one leg over the other, and twist the torso to stretch the core and lower back, relieving tension and improving spinal rotation.
- Seated forward fold: Sit with legs extended and reach forward, stretching the entire back and core, enhancing hamstring flexibility and lower back stretch.
