Psoas minor muscle
Muscles of the iliac and anterior femoral regions (psoas minor visible near top right)
OriginLateral surface bodies of T12 and L1 vertebrae and intervening intervertebral disc
InsertionPectineal line and iliopubic eminence
NerveAnterior ramus of nerve L1
ActionsWeak trunk flexor
AntagonistErector spinae
Latinmusculus psoas minor
Anatomical terms of muscle

The psoas minor muscle (/ˈs.əs/ or /ˈs.æs/; from Ancient Greek: ψόᾱ, romanizedpsóā, 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]


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]


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


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.


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


  1. ^ a b Tank (2005), p 93
  2. ^ a b 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
  8. ^ a b 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