Internal Oblique Muscle Anatomy

Here we can see the internal oblique from an anterior view.

Here we can see the internal oblique from an anterolateral view.

Here we can see the internal oblique from a lateral view.

Here we can see the internal oblique from a posterior view.

Here we can see the internal oblique highlighted in red amongst the other muscles of the body. Due to the internal oblique being a somewhat deep muscle, more superficial muscles like the rectus abdominis and the external oblique have been removed to fully reveal the internal oblique. The muscle underlying the internal oblique here is the transversus abdominis.

Pictured here we can the internal oblique muscle with its aponeurosis connecting into the linea alba at the midline.

Pictured here we can see an origin of the internal oblique muscle on the lateral two thirds of the inguinal ligament (highlighted in red).

Pictured here we can see an origin of the internal oblique muscle on the iliac crest (highlighted in red).

Pictured here we can see an origin of the internal oblique muscle on the thoracolumbar fascia (highlighted in green).

Pictured here we can see an insertion of the internal oblique muscle on the inferior margins of tenth to twelfth rib (highlighted in blue). This is from a posterior view, from an anterior view we will be able to see it connecting onto the adjacent costal cartilages also.

Pictured here we can see the continuation of the insertion on the tenth rib and you can now also see the insertion connecting to the adjacent costal cartilages (highlighted in blue).

Pictured here we can see an insertion of the internal oblique muscle on the linea alba highlighted in blue. The linea alba is a tendinous, fibrous line that runs vertically down the middle of the abdomen.

Pictured here we can see an insertion of the internal oblique muscle (highlighted in blue) on the pectineal line.

This image shows an example of trunk flexion, which involves bending the torso forwards. The opposite of trunk flexion is trunk extension. Bilateral contraction of the internal oblique contributes to trunk flexion.

This image demonstrates trunk lateral flexion, which involves bending the torso to the side. Unilateral contraction of the internal oblique contributes to trunk lateral flexion.

This image demonstrates trunk rotation, which involves twisting the waist/torso to the side. Unilateral contraction of the internal oblique contributes to trunk rotation.

Here we can see the intercostal nerves highlighted in red. These nerves are an innervation of the internal oblique muscle.

Here we can see the subcostal nerve highlighted in red. The subcostal nerve innervates the internal oblique muscle.

Here we can see the iliohypogastric and ilioinguinal nerves labelled. These nerves innervate the internal oblique muscle. The iliohypogastric and ilioinguinal nerves originate from the lumbar plexus, with both nerves arising primarily from the anterior rami of the first lumbar nerve (L1). Sometimes, the iliohypogastric nerve also receives contributions from the twelfth thoracic nerve (T12). The iliohypogastric nerve has two branches, the lateral cutaneous branch and the anterior cutaneous branch. The anterior branch in this picture is the one going around to the front of the body.