03 May 2025
: Case report 
Psoas Quartus and Femoral Nerve Branching: A Case Report and Potential Clinical Implications
Congenital defects / diseases
Joshua Wang
ABCDEF 1, Chun Yeung ABCDEF 1, Eric Chang ABCDEF 1, Jason M. Bourke ABCDE 2*
DOI: 10.12659/AJCR.945927
Am J Case Rep 2025; 26:e945927
Figure 1 Anatomy of the dissected psoas major with anomalous psoas quartus and femoral nerve branching. (A) Anterior view of left side of hip with relevant exposed muscles and nerves. Dashed box indicates highlighted regions in section B–D. (B) Femoral nerve branching around psoas quartus. (C) Psoas major reflected to better expose initial branching path of femoral nerve. (D) Coalescence of femoral nerve branches deep to the inguinal ligament (removed). Note that the psoas quartus retains a fleshy muscle belly more distally than the rest of the psoas major. fem n. – femoral nerve; gen fem n. – genitofemoral nerve; L fem n – lateral femoral cutaneous nerve; p. major – psoas major; p. minor – psoas minor; p. quartus – psoas quartus; quad lumb – quadratus lumborum.