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Psoas minor muscle: want to learn more about it?

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Psoas minor muscle

Often overlooked due to the fact that is sometimes absent, the psoas minor deserves a few moments in the limelight! Check out this short article to find out all you need to know about this muscle! 

Quick facts about the psoas minor muscle
Origin  Vertebral bodies of T12 & L1 vertebrae
Insertion Iliopubic eminence, Pectineal line of pubis
Innervation  Branches of lumbar plexus (L1-L3)
Functions   Weak trunk flexion; Trunk lateral flexion

Anatomy

The psoas minor muscle is a long, slim muscle of the hip joint that runs ventrally to the iliopsoas. Together they make up the inner hip muscles. The psoas minor originates from the lateral surface of the 12th thoracic and 1st lumbar vertebrae, in addition to the intervertebral disc interposed between. Distally, its relatively long tendon inserts on the iliopubic eminence and pectineal line of the pubis. Additionally, fibers of the insertion tendon are attached to the iliac fascia.

Psoas minor muscle (ventral view)

Innervation

The psoas minor is innervated by direct branches of the lumbar plexus (L1-L3). As the muscle lies deep inside the abdomen it is practically not possible to be felt from the outside. The psoas minor is an inconstant muscle and is not found in about 40-70% of all people. You often find instead a thin ligament or broadening of the medial part of the iliopsoas.

Recommended video: Psoas minor
Attachments, innervation and functions of the psoas minor muscle.

Function

As an inner hip muscle, the psoas minor contributes to the stabilization of the pelvis. A unilateral contraction may weakly assist in flexing the lumbar vertebral column to the side (lateral flexion), while a bilateral activation may similarly flex the trunk to the front ( flexion). All in all, this muscle's functions show that it plays a rather subordinate role.

Psoas minor syndrome

Usually the muscle inserts at the pelvis but sometimes the insertion tendon can descend further down up to the femur making it proner to overstrain. In the long run, it becomes stiff and less flexible (psoas minor syndrome). In addition to the limited movement of the hip, this can also result in the development of a malposition of the vertebral column. The affected patients, mostly female teenagers, present with pain in the lower abdomen which is why the psoas minor syndrome is often mistaken for appendicitis. A simple surgical division of the tendon (tenotomy) can completely eliminate any discomfort and restore functionality.

Psoas minor muscle: want to learn more about it?

Our engaging videos, interactive quizzes, in-depth articles and HD atlas are here to get you top results faster.

Sign up for your free Kenhub account today and join over 1,205,167 successful anatomy students.

“I would honestly say that Kenhub cut my study time in half.” – Read more. Kim Bengochea Kim Bengochea, Regis University, Denver

Show references

References:

  • D. Drenckhahn/J. Waschke: Taschenbuch Anatomie, 1st edition, Urban & Fischer Verlag/Elsevier (2008), p. 76
  • Faris et al.: Morphological and morphometric analysis of psoas minor muscle in cadavers, Journal of Morphological Science (2012), vol. 29, no. 4, p. 202-205
  • J. G. Travell/D. G. Simons: Myofascial pain and dysfunction, Lippincott Williams and Wilkins (1998), vol. 1, 2nd edition, p. 95

Author:

  • Achudhan Karunaharamoorthy

Illustrators:

  • Psoas minor muscle (ventral view) - Liene Znotina
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