The abdominal muscles have many important functions: they protect the organs located in the abdominal cavity, help to maintain a proper body posture, but also affect the course of activities such as urinating or breathing. These muscles are divided into two groups, which are the anterolateral muscles and the muscles of the posterior abdominal wall. What exactly are the abdominal muscles and what are their functions?

Abdominal musclesare primarily associated with the fact that their sculpture affects the general appearance of a person. In the human body, these types of muscles definitely do not affect only the aesthetic aspects - the abdominal muscles play many important functions.

Abdominal muscles: split

Generally, the abdominal muscles are divided into two groups: the anterolateral muscle group and the posterior abdominal wall muscle group.

The muscles of the anterolateral wall include the following muscles:

  • external oblique abdominal muscle,
  • internal oblique abdominal muscle,
  • transverse abdominal muscle,
  • rectus abdominis muscle,
  • pyramidal muscle.

The second group of abdominal muscles - that is the muscles of the back wall - includes:

  • lumbar trapezius,
  • major lumbar muscle,
  • minor lumbar muscle,
  • hip muscle.

Abdominal muscles: muscles of the anterolateral wall

The external oblique abdominal muscle begins on the outer surface of the ribs 5 to 12, while the end attachment of this muscle is located on the pubic tubercle and the anterior superior iliac spine, the outer lip of the pubic crest and within the white line. It participates in the movements of the chest and spine, and the external oblique muscle is also involved in the breathing process (it works as the expiratory muscle).

The internal oblique abdominal muscle has its initial attachment in the thoracolumbar fascia, the intermediate lip of the iliac crest and in the lateral part of the inguinal ligament.

The end attachment of this muscle is located on the lower edges of the ribs 10 to 12, the crest of the pubic bone (to which it is attached through the tendon) and within the white line.

Oblique muscleThe internal abdominal muscle has a similar function to the external oblique muscle - it is also involved in the movements of the chest and spine and functions as the expiratory muscle.

The transverse abdominal muscle begins on the inner surface of the costal cartilages up to 7 to 12, on the inner lip of the iliac crest, and within the inguinal ligament and the lumbar-thoracic fascia.

This terminal muscle is attached to the crest of the pubic bone (to which it attaches via the tendon) and within the white line. The transverse abdominis muscle constricts the rib cage, which ultimately makes it known as an expiratory muscle.

The rectus abdominis muscle has its initial attachment on the xiphoid process and on the outer surface of the costal cartilages from 5 to 7. The final attachment of this muscle is on the pubic symphysis and on the pubic crest.

The rectus abdominis muscle, like the previously discussed muscles, is classified as the expiratory muscle, and is also involved in bending the torso forward.

The pyramidal muscle has its initial attachment on the pubic symphysis and on the branch of the upper pubic bone, while it ends within the white line. Its function is to tighten the white border.

Abdominal muscles: muscles of the back wall

The trapezius muscle of the loins begins at the costal processes of the lumbar vertebrae L1 to L5, the inner lip of the iliac crest and the iliopsoas ligament.

The end attachment of this muscle is located on the lower edge of the twelfth rib and on the body of the twelfth thoracic vertebrae. The function of the trapezius muscle of the loins is to stabilize the spine in the lumbar spine, and it is also involved in bending the torso to the side.

The greater lumbar muscle has its initial attachment on the lateral surfaces of the twelfth thoracic vertebrae and the first lumbar vertebra, and on the costal processes of the lumbar vertebrae from L1 to L4.

The end attachment of this muscle is located on the lesser trochanter of the femur. The lumbar minor muscle is responsible for laterally bending the lumbar spine, and besides - along with the hip muscle - it is responsible for bending the thigh.

The minor lumbar muscle begins on the bodies of the last thoracic vertebrae and the first lumbar vertebra, and ends in the iliopsoas fascia. The function of the psoas minor muscle is to tighten the iliac fascia and the iliopubic arch.

The iliac muscle, the last muscle of the posterior abdominal wall, begins at the iliac spinesanterior, iliac fossa and anterior sacroiliac ligament. The end attachment of the muscle is located on the lesser trochanter of the femur. The hip muscle is responsible for bending the thigh and stabilizing the hip joint.

Abdominal muscles: innervation

Complicated are not only the division of the abdominal muscles and the knowledge of their exact location, but also the innervation of each of them. The muscles of the back wall are generally innervated by the branches of the lumbar plexus, additionally:

  • the lumbar trapezius muscle is also innervated by the subcostal nerve,
  • the psoas major muscle and the psoas minor muscle are also innervated by the femoral nerve.

The external oblique abdominal muscle and the internal oblique abdominal muscle have the same innervation - they are innervated by the 5 to 12 intercostal nerves, the subcostal nerve, the ilio-hypogastric nerve and the ilio-inguinal nerve.

The innervation of the transverse abdominal muscle is similar, which - apart from the nerves mentioned above - is also supplied by the genitourinary nerve. The rectus abdominis muscle is innervated by the intercostal nerves 7 to 12, while the pyramidal muscle is supplied by the subcostal nerve.

Abdominal muscles: features

The primary role of the abdominal muscles is to protect the delicate organs located inside the abdominal cavity - they are, after all, part of the abdominal wall. However, there are also other functions of the abdominal muscles - they correspond, among others, to for the correct mobility of the torso and affect the ability of a person to maintain a proper body posture.

It was previously mentioned that the abdominal muscles - or at least some of them - belong to the group of expiratory muscles. They are classified because of the fact that by compressing the organs of the abdominal cavity and increasing the pressure in it, their activity leads to the elevation of the diaphragm, which facilitates exhalation.

It is also worth mentioning here that by interacting with other muscles, the abdominal muscles influence the course of various physiological processes, such as, in particular, urination or stool. The abdominal muscles also play a role in labor.

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