Abdominal internal oblique muscle

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Abdominal Internal Oblique Muscle

The Abdominal Internal Oblique Muscle is a key component of the human anatomy, playing a crucial role in the abdominal wall's structure and function. It is one of the flat muscles that contribute to the abdominal musculature, lying just beneath the external oblique muscle and above the transversus abdominis muscle. This muscle is instrumental in various bodily functions, including respiration, posture, and movements of the trunk.

Anatomy

The Abdominal Internal Oblique Muscle originates from the thoracolumbar fascia, the iliac crest, and the inguinal ligament. It fans out as it moves anteriorly, inserting into the linea alba, pubic crest, and the lower ribs, typically the last three or four. The fibers of this muscle run perpendicular to those of the external oblique muscle, creating a crisscross pattern that adds strength and stability to the abdominal wall.

Function

The primary functions of the Abdominal Internal Oblique Muscle include:

• Assisting in the process of respiration by helping to compress the abdominal cavity, which increases intra-abdominal pressure and aids in forced expiration.
• Contributing to the movement and stabilization of the trunk by facilitating flexion, lateral flexion, and rotation of the spine. When the muscle contracts unilaterally, it causes the trunk to rotate and flex to the same side. Bilateral contraction results in trunk flexion and compression of the abdominal contents.
• Supporting the abdominal organs and maintaining abdominal pressure, which is essential for functions such as defecation, urination, and childbirth.

Innervation

The Abdominal Internal Oblique Muscle is innervated by the lower six thoracoabdominal nerves and the first lumbar nerves, which are branches of the spinal nerves. This innervation is crucial for the muscle's motor and sensory functions.

Clinical Significance

Injuries or strains to the Abdominal Internal Oblique Muscle can occur due to overuse, sudden movements, or direct trauma. Such injuries are common in athletes and can lead to pain, decreased mobility, and difficulty in performing tasks that involve trunk rotation or flexion. Treatment typically involves rest, physical therapy, and, in severe cases, surgical intervention.

See Also

• External Oblique Muscle
• Transversus Abdominis Muscle
• Rectus Abdominis Muscle
• Abdominal Wall