Psoas major muscle

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The Psoas major is a long fusiform muscle placed on the side of the lumbar region of the vertebral column and brim of the lesser pelvis.

[edit] Origins

It arises:

• (1) from the anterior surfaces of the bases and lower borders of the transverse processes of all the lumbar vertebræ
• (2) from the sides of the bodies and the corresponding intervertebral fibrocartilages of the last thoracic and all the lumbar vertebræ by five slips, each of which is attached to the adjacent upper and lower margins of two vertebræ, and to the intervertebral fibrocartilage;
• (3) from a series of tendinous arches which extend across the constricted parts of the bodies of the lumbar vertebræ between the previous slips; the lumbar arteries and veins, and filaments from the sympathetic trunk pass beneath these tendinous arches.

[edit] Insertion

The muscle proceeds downward across the brim of the lesser pelvis, and diminishing gradually in size, passes beneath the inguinal ligament and in front of the capsule of the hip-joint and ends in a tendon; the tendon receives nearly the whole of the fibers of the Iliacus and is inserted into the lesser trochanter of the femur.

A large bursa which may communicate with the cavity of the hip-joint, separates the tendon from the pubis and the capsule of the joint.

[edit] Function

It forms part of a group of muscles called the hip flexors, whose action is primarily to lift the upper leg towards the body or to pull the body towards the leg (it is the group that performs the action of a "sit-up").

[edit] Additional images

Diagram of a transverse section of the posterior abdominal wall, to show the disposition of the lumbodorsal fascia.	The diaphragm. Under surface.	Muscles of the iliac and anterior femoral regions.	The arteries of the pelvis.
The relations of the femoral and abdominal inguinal rings, seen from within the abdomen. Right side.	The thoracic and right lymphatic ducts.	The lumbar plexus and its branches.	Nerves of the right lower extremity. Front view.
Sacral plexus of the right side.	Transverse section, showing the relations of the capsule of the kidney.

[edit] External links

• GPnotebook -1261436848
• LUC psmj
• SUNY Labs 40:16-0101 - "Posterior Abdominal Wall: Muscles of the Posterior Abdominal Wall"
• SUNY Anatomy Image 8916
• Cross section at UV pelvis/pelvis-e12-2

This article was originally based on an entry from a public domain edition of Gray's Anatomy. As such, some of the information contained herein may be outdated. Please edit the article if this is the case, and feel free to remove this notice when it is no longer relevant.

es:Psoas mayor