What are they
The abdominals are a group of muscles present, as the name implies, in the abdomen in two layers, one superficial and one deeper.
The former are the anterolateral muscles of the abdomen, the latter the posterior muscles of the abdomen.
Taken together, they constitute a system that fulfils several important functions. On the one hand they guarantee balance, the right posture of the back and the movements of the trunk, legs and rotation of the pelvis.
On the other hand, they are essential for the tightness of the viscera and the correct mechanics of breathing.
What are they?
The anterolateral muscles of the abdomen are four symmetrical pairs (located to the right and left of the midline): the rectum, the external oblique (or large oblique), the internal oblique (or small oblique) and the transverse.
The posterior muscles of the abdomen, also in symmetrical pairs, form the posterior abdominal wall. They include: the quadrate of the loins, the iliac and the psoas.
What they do
The following table shows the functions of the different abdominal muscles:
Muscles | Function |
---|---|
Rectus abdominis | Each rectus abdominis flexes the trunk and tilts it to its side; In addition, it lowers the ribs acting as an expiratory muscle (reduces size of the ribcage allowing the escape of air from the lungs) |
External oblique and internal oblique | Each external oblique and internal oblique flexes, tilts from its own side and rotate the trunk; it also lowers the ribs acting as a muscle Expirator |
Transverse | Each transverse rotates the trunk and lowers the ribs (expirator), but intervenes above all when exhalation is forced. Forms a real muscular corset able to contain the belly |
Square of loins | Each square of the loins flexes the spine on its side and the pelvis; also helps the functioning of other muscles sit-up. Contracting lowers the twelfth rib (muscle expirator). Bilateral contraction extends the lumbar tract of the spine |
The concomitant contraction of all the large muscles of the abdomen compresses the viscera favoring the expulsion of feces and urine (abdominal press). Each iliopsoas muscle flexes the thigh, rotates it medially and participates in the flexion of the trunk.
It also participates in the maintenance of the pelvis. With its contraction, lumbar lordosis increases, i.e. the physiological curvature of the spine at the level of the last part of the back, and its hypertonicity can cause annoying low back pain.
If they weaken
Weakening of the rectus and external and internal oblique muscles (torso flexor muscles), especially if it is associated with a weakening of those of the thigh as well, involves a variation in the position of the pelvis, with a consequent accentuation of lumbar lordosis.
This often leads to the occurrence of back pain (lumbar pain) as the loads on the intervertebral discs are abnormally distributed.
Joycelyn Elders is the author and creator of EmpowerEssence, a health and wellness blog. Elders is a respected public health advocate and pediatrician dedicated to promoting general health and well-being.
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