Psoas minor muscle

The psoas minor muscle (/ˈsoʊ.əs/ or /ˈsoʊ.æs/; from Ancient Greek: ψόᾱ, romanized: psóā, lit. 'muscles of the loins') is a long, slender skeletal muscle.^[1][2] When present, it is located anterior to the psoas major muscle.^[1][2]

Psoas minor muscle
Muscles of the iliac and anterior femoral regions (psoas minor visible near top right)
Details
Origin	Lateral surface bodies of T12 and L1 vertebrae and intervening intervertebral disc
Insertion	Pectineal line and iliopubic eminence
Nerve	Anterior ramus of nerve L1
Actions	Weak trunk flexor
Antagonist	Erector spinae
Identifiers
Latin	musculus psoas minor
TA98	A04.7.02.005
TA2	2596
FMA	22350
Anatomical terms of muscle [edit on Wikidata]

Structure

The psoas minor muscle originates from the vertical fascicles inserted on the last thoracic and first lumbar vertebrae. From there, it passes down onto the medial border of the psoas major, and is inserted to the innominate line and the iliopectineal eminence. Additionally, it attaches to and stretches the deep surface of the iliac fascia and occasionally its lowermost fibers reach the inguinal ligament.^[3] It is posteriolateral to the iliopsoas muscle.^[4] Variations occur, however, and the insertion on the iliopubic eminence sometimes radiates into the iliopectineal arch.^[5]

The psoas minor muscle receives oxygenated blood from the four lumbar arteries (inferior to the subcostal artery) and the lumbar branch of the iliolumbar artery.^{[citation needed]}

Innervation

The psoas minor muscle is innervated by direct branches of the lumbar spinal nerves.^[6]

Variation

The psoas minor muscle is considered inconstant and is often absent, only being present in about 40% of human specimens studied.^[7] It has an average length of about 24 cm, of which about 7.1 cm is muscle tissue and about 17 cm is tendon.

Function

The psoas minor is a weak flexor of the lumbar vertebral column.

Other animals

The psoas minor muscle is present in other mammals, such as horses.^[8] In horses, it may be palpated during rectal exams to check for causes of back pain.^[8]

Additional images

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  Right hip bone, internal surface
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  Right femur, posterior surface
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  Psoas minor muscle
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  Psoas minor muscle
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  Psoas minor muscle

Notes

1. Tank (2005), p 93
2. Gray (2008), p 1372
3. Bendavid (2001), p 58
4. Zwingenberger, Allison; Benigni, Livia; Lamb, Christopher R. (2015-01-01), Mattoon, John S.; Nyland, Thomas G. (eds.), "Chapter 14 - Musculoskeletal System", Small Animal Diagnostic Ultrasound (Third Edition), St. Louis: W.B. Saunders, pp. 517–540, ISBN 978-1-4160-4867-1, retrieved 2021-01-22
5. Platzer (2004), p 234
6. Gardner, ERNEST D.; Bunge, RICHARD P. (2005-01-01), Dyck, Peter J.; Thomas, P. K. (eds.), "Chapter 2 - Gross Anatomy of the Peripheral Nervous System", Peripheral Neuropathy (Fourth Edition), Philadelphia: W.B. Saunders, pp. 11–33, ISBN 978-0-7216-9491-7, retrieved 2021-01-22
7. Mcg Farias (1 Jan. 2012). Morphological and morphometric analysis of Psoas Minor Muscle in cadavers. ResearchGate. Retrieved from https://www.researchgate.net/publication/280236296_Morphological_and_morphometric_analysis_of_Psoas_Minor_Muscle_in_cadavers
8. Haussler, Kevin K.; Jeffcott, Leo B. (2014-01-01), Hinchcliff, Kenneth W.; Kaneps, Andris J.; Geor, Raymond J. (eds.), "21 - Back and pelvis", Equine Sports Medicine and Surgery (Second Edition), W.B. Saunders, pp. 419–456, ISBN 978-0-7020-4771-8, retrieved 2021-01-22

References

• Bendavid, Robert; Abrahamson, Jack; Arregui, Maurice E. (2001). Abdominal Wall Hernias: Principle and Management. Springer. ISBN 0-387-95004-4.
• Platzer, Werner (2004). Color Atlas of Human Anatomy, Vol 1: Locomotor system (5th ed.). Thieme. ISBN 3-13-533305-1. (ISBN for the Americas 1-58890-159-9.)
• Tank, Patrick W. (2005). Grant's Dissector (13th ed.). Hagerstown, MD: Lippincott Williams & Wilkins. ISBN 0-7817-5484-4.
• Gray, Henry; Standring, Susan (2008). Gray's Anatomy - The Anatomical Basis of Clinical Practice (40th ed.). Churchill Livingstone - Elsevier. ISBN 978-0-443-06684-9.