Anatomy and Function of the Anterior Abdominal Muscle

Hello everyone, thank you for taking the time to read my previous post, I am also happy to have you here today. Today, I will be explaining about the Abdominal wall muscles. I will be discussing the Anterior and Posterior Abdominal walls. The abdominal wall muscles are a group of muscles located in the front of the abdomen responsible for movement and support of the trunk. Let's begin with the Anterior Abdominal wall.

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The Anterior Abdominal Wall

The anterior abdominal wall is the front part of the abdomen which works to protect organs within the abdominal cavity and also assist in posture and movement. It is composed of five muscles which are the Pyramidalis muscle, Rectus Abdominis muscle (known as the Six-pack muscle), External Abdominal Oblique Muscle, Internal Abdominal Oblique Muscle, and the Transversus Abdominis Muscle.

Pyramidalis Muscle

The pyramidalis muscle is a small triangular-shaped muscle found within the rectus sheath, superficial to the inferior part of the rectus abdominis. It originates from the pubic crest where the muscle blends with the pubic symphysis. The pyramidalis muscle moves to blend into the linea alba which is the midline of the rectus sheath. The pyramidalis muscle helps to tense the linea alba when there is an abdominal contraction. It also serves as a proprioceptor muscle There are a lot of people who are not born with this muscle, as its presence has been reported to be as low as 30% and as high as 90%, with some people not having it on one side or the other of the abdomen, but that doesn't affect their ability to tense the linea alba during abdominal contraction. The Pyramidalis Muscle is innervated by the T12 Subcostal nerve and its blood supply is via the inferior epigastric artery.

Rectus Abdominis

The Rectus Abdominis muscle is the most superficial core anterior abdominal wall muscle. This muscle is a segmented muscle (divided into different segments, and that's why if you see that 6 pack abs) each muscular segment is separated by tendinous intersections and divided by the linea alba which starts from the pubic symphysis inferiorly going upwards till it reaches the xiphoid process. The Rectus Abdominus begin at the pubic symphysis and around the pubic crest laterally. The fiber muscles run vertically to reach the xiphoid process and the costal cartilages of the ribs 5 to 7. It is important for trunk flexion, it compresses the abdominal viscera during intense efforts and forced expiration. It is innervated by the intercostal nerve within T7 and T11, and by the subcostal nerve in T12. The Rectus abdominis gets blood supply from the inferior epigastric artery, superior epigastric artery, subcostal artery, deep circumflex artery, and posterior intercostal artery.

External Abdominal Oblique Muscle

It is an important muscle with its fibers running downwards and forwards, having its origin at the outer surface of ribs 5 to 12. The External abdominal oblique muscle inserts downwards and linearly to the linea alba, the pubic tubercle, and the iliac crest. The External Abdominal Oblique Muscle was innervated by the thoracoabdominal and subcostal nerve innervating within the T7 to T12. The External Abdominal Oblique Muscle flexes and rotates the trunk, as well as to compresses and supports the internal viscera. This is very important when passing feces out as it puts pressure on the vertebral column.

Internal Abdominal Oblique Muscle

The Internal Oblique muscle runs in the opposite direction to the external oblique. It originates from the anterior iliac crest, and thoracolumbar fascia, and attaches to the lateral third of the inguinal ligament. It runs upwards into the 10th and 12th rib, and from the linea alba. It is supplied similarly to the External Abdominal Oblique Muscle, by the thoracoabdominal and subcostal nerves coming from T6 to T12. The Internal Abdominal Oblique Muscle and External Abdominal Oblique Muscle perform the same function which is rotating and flexing the trunk and compressing and supporting the internal viscera.

Transversus Abdominis Muscle

The fibers of the Transversus Abdominis Muscle run horizontally or transversely as its name implies. The Transversus Abdominis Muscle is the deepest core muscle and it is located at the lateral abdominal wall, deep into the oblique muscles. It originates from the 7th rib through the 12th rib around the internal surfaces of the costal cartilages, it also originates from the thoracolumbar fascia, its origins also comes from the anterior two third of the iliac crest, and the iliopectineal arch. It runs through the linea alba, internal oblique, pubic crest, and the pectinal line of the pubis. It compresses the abdominal viscera during forced expiration and intense effort, facilitates ipsilateral trunk rotation, braces the spine and the abdominal contents, and opens the vertebral canal during intense effort which puts loads off the spine. It is innervated by the intercostal nerve from T7 to T11, the subcostal nerve of T12, and sensory innervation from the Iliohypogastric nerve at L1, and the Ilioinguinal nerve at L1. The muscle is supplied by the lower posterior intercostal and subcostal artery, superior and inferior epigastric artery, superficial and deep circumflex artery, and the posterior lumber artery.

Conclusion

The abdominal muscle is very important to protect the abdomen and the spine, and helps in exhalation and compression. I was able to discuss the anterior abdominal wall today, and in my next post, I will be bringing up the posterior abdominal wall. Thanks for reading my post.

Reference

Hi, I am Tobi a writer, speaker, relationship blogger, and lover of good music. I love making friends and learning from people. Want to hear me speak on relationships and general life issues, you can find my podcast channel Here and I also have a youtube channel where you can listen and watch any episode for free, do not forget to subscribe and share with friends. I sincerely appreciate every love I get from members of the community and do well to keep them coming.