Rectus Abdominis (*Abs)
Abdomen · Trunk
The rectus abdominis is the long, paired strap muscle that runs vertically down the front of the abdomen on either side of the midline, giving the six-pack appearance. It arises from the pubic crest, pubic tubercle, and pubic symphysis and ascends to insert on the xiphoid process and the costal cartilages of ribs 5 to 7. Its main action is flexion of the trunk, drawing the ribcage toward the pelvis, and it also compresses the abdominal viscera and helps stabilise the pelvis. The muscle is enclosed in the rectus sheath and is crossed by several fibrous tendinous intersections that create the segmented appearance and are anchored to the linea alba in the midline. It is supplied by the thoracoabdominal nerves, the anterior rami of T7 to T12.
Origin, Insertion, Action & Nerve
Origin
Pubic crest, pubic tubercle, and pubic symphysis
Insertion
Xiphoid process and costal cartilages of ribs 5–7
Action
Flexion of trunk; compresses abdominal viscera; stabilizes pelvis
Nerve
Thoracoabdominal nerves, anterior rami of T7–T12
Attachments explained
The Rectus Abdominis (*Abs) is defined first by where it attaches. Its origin is the more fixed anchor, usually the proximal or more stable end that stays put during contraction, while its insertion is the more mobile point that is pulled toward the origin when the muscle shortens.
Origin
Pubic crest, pubic tubercle, and pubic symphysis
Insertion
Xiphoid process and costal cartilages of ribs 5–7
Action & function
When the Rectus Abdominis (*Abs) contracts, it produces the following movements: Flexion of trunk; compresses abdominal viscera; stabilizes pelvis.
As part of the Abdomen group of the Trunk, it works alongside neighbouring muscles to generate smooth, coordinated movement and to stabilise the structures it acts on.
Nerve supply & clinical relevance
The Rectus Abdominis (*Abs) receives its nerve supply from the Thoracoabdominal nerves, anterior rami of T7–T12. This nerve carries fibres from spinal segment(s) T7, T12.
Because a muscle can only contract when its nerve is intact, injury to the Thoracoabdominal nerves, anterior rami of T7–T12 or to its spinal roots (T7, T12) can weaken or paralyse the Rectus Abdominis (*Abs), impairing the movements it normally produces (flexion of trunk). This is why knowing the innervation is central to localising nerve lesions in clinical practice.
How to study the Rectus Abdominis (*Abs) (the OIANS method)
Anchor rectus abdominis by its vertical run from pubis to lower ribs and sternum, which makes its main action obvious: shortening the distance between ribcage and pelvis flexes the trunk, the movement of a sit-up or crunch. Remembering the tendinous intersections that bind it to the linea alba explains the visible six-pack segmentation.
Tie the innervation to a broad segmental pattern rather than a single named nerve: the thoracoabdominal nerves T7 to T12 supply it in bands, mirroring the same intercostal nerves that continue onto the abdominal wall. Grouping it with pyramidalis, the small muscle lying in front of its lower end, and noting its role in compressing the abdomen links it to the wider anterior abdominal wall.
Frequently asked questions
Where is the Rectus Abdominis (*Abs) located?
The Rectus Abdominis (*Abs) is a muscle of the Abdomen group, located in the Trunk.
What is the origin of the Rectus Abdominis (*Abs)?
Pubic crest, pubic tubercle, and pubic symphysis
What is the insertion of the Rectus Abdominis (*Abs)?
Xiphoid process and costal cartilages of ribs 5–7
What movements does the Rectus Abdominis (*Abs) produce?
Flexion of trunk; compresses abdominal viscera; stabilizes pelvis
What nerve supplies the Rectus Abdominis (*Abs)?
Thoracoabdominal nerves, anterior rami of T7–T12
Is the Rectus Abdominis (*Abs) free to study in OIANS?
The Rectus Abdominis (*Abs) is always free to browse. Its full origin, insertion, action and nerve details are open to everyone in the Muscle Directory. Quiz and Flashcard practice for the Trunk is part of the one-time Lifetime upgrade, though; only the Upper Limb decks are free to test yourself on.
Related muscles
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