|Origin||Vertebral bodies of T12-L1 vertebrae and adjacent intervertebral disc|
|Insertion||Iliopectineal eminence and pectineal line of the pubis (pecten pubis)|
|Action||Very weak flexion of the trunk|
|Nerve||Anterior ramus of first lumbar nerve (L1)|
Location & Overview
The psoas minor is flat and relatively thin muscle located in the lumbar region of the back and extending to pubis region. It is able to provide very weak flexion of the trunk, specifically in the lumbar region. It is superficial to the psoas major muscle and the iliacus muscle (meaning it is more anterior than both of these muscles and closer to the skin’s surface). The psoas minor and major muscles are sometimes referred to collectively as the ‘psoas muscle’  . The psoas minor muscle is bilaterally absent (missing from both sides) for about 40% of the population. It can also be missing unilaterally (from just one side) .
The name of the psoas minor muscle is believed to have originated from the Ancient Greek word ‘ψόᾱ’, meaning ‘psoas’, which translates to ‘muscles of the loins’ in English.
Origin & Insertion
The psoas minor muscle originates from the last thoracic and first lumbar vertebrae (T12-L1). It also originates from the and adjacent intervertebral disc (i.e it connects to the disc between T12-L1). The psoas minor then continues in an inferior direction towards the pelvis and inserts on the iliopectineal eminence and pectineal line of the pubis (aka pectin pubis) via a long tendon   . Guerra, et al. determined that the tendon comprised 57% of the total length of the muscle .
The psoas minor provides very weak assistance during flexion of the trunk. The absence of the psoas minor is some individuals does not seem to result in reduced functionality suggesting it is a relatively unimportant muscle, especially when compared to its psoas major counterpart   .
The psoas minor is innervated by the anterior ramus of first lumbar nerve (L1) .
Blood is supplied to the psoas minor mainly via the lumbar arteries.
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Psoas Minor Flashcards
|↑1, ↑5, ↑8||Bordoni B, Varacallo M. Anatomy, Bony Pelvis and Lower Limb, Iliopsoas Muscle. [Updated 2022 Apr 29]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK531508/|
|↑2, ↑6, ↑10, ↑11||Protas M, Voin V, Wang JM, Iwanaga J, Loukas M, Tubbs RS. A Rare Case of Double-Headed Psoas Minor Muscle with Review of its Known Variants. Cureus. 2017;9(6):e1312. Published 2017 Jun 5. doi:10.7759/cureus.1312|
|↑3, ↑4, ↑9||Dragieva P, Zaharieva M, Kozhuharov Y, Markov K, Stoyanov GS. Psoas Minor Muscle: A Cadaveric Morphometric Study. Cureus. 2018;10(4):e2447. Published 2018 Apr 8. doi:10.7759/cureus.2447|
|↑7||Anatomical study of the psoas minor muscle in human fetuses (article in Spanish-English) Guerra DR, Reis FP, Bastos AdA, et al. http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-95022012000100024&lng=en&nrm=iso&tlng=en Int J Morphol. 2012;30:136–139.|