GET TO KNOW YOUR ABDOMINALS
Most people know the abdominals as the visible ‘six-pack’ muscle that we all crave and very few of us ever achieve. However, the abdominals are far more than just a pretty face: they protect the soft organs within the abdominal cavity in the way that the ribcage protects the heart, lungs and liver; they assist with breathing as when you inhale the abdominals relax to allow the diaphragm to descend and when you exhale the abdominals contract to assist the diaphragm in ascending; the abdominals help to create intra-abdominal pressure which is necessary in order to cough, sneeze, urinate, defecate and give birth.
Five muscles make up the anterior abdominal wall, Transversus Abdominis (TVA), Internal Obliques, External Obliques, Rectus Abdominals and Pyramidalis (which is tiny, not present in everyone and will not be discussed further!).
Transversus Abdominis
The deepest abdominal is Transverus Abdominis. This is a large muscle that wraps around the waist, with fibres running horizontally. It attaches to the ribs and the pelvis on the left and the right side of the torso and then continues into a large fibrous sheath of connective tissue called the aponeurosis.
The TVA is often referred to as the body’s girdle or corset and is the muscle that we really try to focus on in Pilates classes due to its inherent spine-stabilising role.
The fibres of the TVA are oriented horizontally i.e. transversally and wrap around the waist attaching to the ribs, pelvis and breastbone. As the fibres come towards the midline of the body, they form a tendonous, connective tissue called the aponeurosis. This is the white area you can see on diagrams of the abdominals.
In this diagram you can see clearly how the TVA muscle wraps around the waist, around to the fascia of the lumbar spine. When this muscle is strong and functioning well it offers huge support to the lumbar spine and acts like a brace for the torso. If this muscle is weak, the ribcage is more likely to flair up (which will have a knock-on effect on respiration), the pelvis will lack optimal support, which may result in a posterior pelvic tilt and the lumbar spine will have lost one of its major stabilising forces, resulting in too much mobility, possibly leading to pain and/or injury.
A weakened TVA will also reduce your body’s ability to create intra-abdominal pressure. Along with creating a stabilising force for the spine, intra-abdominal pressure is the vital component needed when trying to expel anything from your body, including faeces. So, if you’re straining to go to the loo, it might not just be a case of eat more fibre.
INTERNAL AND EXTERNAL OBLIQUES
Sat on top of the TVA are the Internal Oblique muscles, one on either side of the torso. The fibres run diagonally, they attach to the ribs and the pelvis and converge into the abdominal aponeurosis. Internal Obliques have a role to play in increasing intra-abdominal pressure, they also aid in flexing the torso (bending forward from the waist), lateral flexion (side bend) and trunk rotation (twisting from the wasit).
The External Oblique fibres run perpendicular to those of the Internal Obliques. They attach to the lowest eight ribs, the pelvis and the aponeurosis. When used unilaterally, these muscles will flex the torso laterally to the same side as the contraction. Used bilaterally, these muscles will help to flex the trunk at the waist. They also aid in the maintenance of intra-abdominal pressure and forced respiration.
Strong Oblique muscles help to stabilise the spine and help to create good posture. i.e. a neutral spine with the ribcage stacked directly over the pelvis. Â If these muscles become weak, there is a greater chance that a poor posture may develop, leading to possible pain and/or injury. It is important that both the left and the right muscles are equally strong and flexible as an imbalance may lead to unwanted postural changes.
RECTUS ABDOMINIS
The holy grail of the Instagram gym-bunny. The good news is that everyone has a six pack. The bad news is that very few of us can see it as, typically, body fat percentage must be very low, 14-20% in men and 6-13% in women.
The Rectus Abdominis run straight down the midline of the body from the sternum, attaching onto some ribs (5-7) as it goes, and ending up on the pubic bone (Rectus mean straight in Latin). They are paired muscles, both attaching to the central Linea Alba. Functionally, the Rectus Abdominis flex the trunk, bending the torso forward. They also act to compress the internal organs (viscera) and help with increasing intra-abdominal pressure. These muscles have a stabilising role on the pelvis during the gait cycle and they act to depress the ribs.
