This sheath is not uniform from top to bottom. Above your navel (umbilicus), the aponeuroses split and pass both in front of and behind the rectus muscle. Below the navel, all the aponeuroses pass in front of the rectus muscle, leaving the lower part of the muscle unsupported from behind. This anatomical "weak spot" is why lower abdominal hernias are more common.
The is a flat, expansive sheet of pearly-white fibrous tissue that serves as the primary structural connector between the large muscles of the abdominal wall and their attachment points. Unlike cord-like tendons, aponeuroses are broad and sheet-like, providing the tension and stability necessary for core movement, organ protection, and respiratory support. Anatomy and Layered Structure abdominal aponeurosis
: Situated beneath the external oblique, this layer splits to wrap around the rectus abdominis muscle, contributing to both the anterior and posterior rectus sheaths. This sheath is not uniform from top to bottom
The anterior abdominal wall is comprised of several layers of aponeurotic tissue that interweave to form a powerful containment system for the viscera. This anatomical "weak spot" is why lower abdominal
All three aponeuroses converge at the midline of the belly to form a tough, fibrous band called the (Latin for "white line"). The linea alba runs vertically from the bottom of the sternum (breastbone) to the pubic bone.