The Musculus obliquus internus abdominis (lat. for „ internal oblique abdominal muscle“) is one of the abdominal muscles. The fibers run from kaudolateral (down-outward) to kraniomedial (up-inward). They cross with the fibers of the Musculus obliquus externus abdominis in a 90° degree angle. The wide tendon plate (Aponeurose) forms together with the Musculus obliquus externus abdominis and the Musculus transversus abdominis the Linea alba.
Origin
Lig. inguinale, Crista iliaca, Spina iliaca anterior superior, Fascia thoracolumbalis, Processus costales L1-L5
Projection
Cartilage of the lower four rips, Linea alba
Function
Bending the trunk, Exspiration
Innervation
Nervi intercostales, Nervi subcostales, Nervus ilioinguinalis, Nervus iliohypogastricus