Anatomical variability of the lumbosacral plexus: A review of clinical implications

Abstract

The lumbosacral plexus (LSP) is a complex neural network that provides motor and sensory innervation to the lower limbs, pelvic organs, and perineal region. Although traditionally depicted as a fixed structure in anatomical literature, recent cadaveric dissections, radiological imaging, and surgical observations have revealed significant morphological variations within the LSP. This review synthesizes studies published between 2000 and 2025, classifying and evaluating the prevalence and clinical relevance of anatomical deviations in both lumbar and sacral components of the plexus. Variations in the origin and course of nerves such as the ilioinguinal, genitofemoral, lateral femoral cutaneous, femoral, and obturator nerves pose critical risks during surgical procedures and regional anesthesia. At the sacral level, alterations in the morphology of the piriformis muscle affect the pathway of the sciatic nerve, potentially leading to conditions such as piriformis syndrome, nerve entrapments, and failed nerve blocks. Additionally, anatomical variations of less emphasized nerves like the pudendal and posterior femoral cutaneous nerves carry significant implications for pelvic surgeries. These findings highlight the limitations of relying solely on “average” anatomical models and underscore the necessity of individualized surgical planning. The integration of advanced techniques such as MR neurography and intraoperative neuromonitoring into routine clinical practice can aid in identifying anatomical variations preoperatively, thereby minimizing complication risks and improving patient outcomes.

Keywords

• Lumbosacral plexus
• anatomical variation
• peripheral nerves

References

1. Zielinska N, Posnik M, Kaczmarczyk I, Klejbor I, Triantafyllou G, Maranillo E, et al. Lumbar plexus - review. Folia Morphol (Warsz). 2025;84(1):1-21.
2. Wang J, Yeung C, Chang E, Bourke JM. Psoas Quartus and Femoral Nerve Branching: A Case Report and Potential Clinical Implications. Am J Case Rep. 2025 May 3;26:e945927.
3. Barakat R, Karaflou VM, Giavopoulos P, Pappas N, Tsakotos G, Filippou D. Obturator Nerve Variations: A Narrative Review. Acta Med Acad. 2024 Dec;53(3):328-34.
4. Tomlinson J. B15 Current insights into hip joint innervation. Regional Anesthesia & Pain Medicine. 2024;49(Suppl 1):A348-A50.
5. Soldatos T, Andreisek G, Thawait GK, Guggenberger R, Williams EH, Carrino JA, et al. High-resolution 3-T MR neurography of the lumbosacral plexus. Radiographics. 2013 Jul-Aug;33(4):967-87.
6. Bronner ME, LeDouarin NM. Development and evolution of the neural crest: an overview. Dev Biol. 2012 Jun 1;366(1):2-9.
7. Anetai H, Teramoto J, Ono T, Kiribayashi T, Nojiri H, Ohara Y, et al. 12th Rib Length as a Predictor of Anatomical Variations in the Lumbosacral Plexus Associated with Atypical Radiculopathy in Lumbar Disc Herniation. Spine (Phila Pa 1976). 2025 May 29.
8. Elsy B, Asiri WHM, Osman L, Alghamdi MAS. Origin and branching pattern of the iliohypogastric and ilioinguinal nerves and their exits in relation to the psoas major muscle: a cadaveric study. Anat Cell Biol. 2025 Mar 31;58(1):14- 21.

9. Geh N, Schultz M, Yang L, Zeller J. Retroperitoneal course of iliohypogastric, ilioinguinal, and genitofemoral nerves: A study to improve identification and excision during triple neurectomy. Clin Anat. 2015 Oct;28(7):903-9.
10. Dalili D, Isaac A, Fritz J. Selective MR neurography-guided lumbosacral plexus perineural injections: techniques, targets, and territories. Skeletal Radiol. 2023 Oct;52(10):1929-47.
11. Yasar S, Kaya S, Temiz C, Tehli O, Kural C, Izci Y. Morphological structure and variations of lumbar plexus in human fetuses. Clin Anat. 2014 Apr;27(3):383-8.
12. Cancado de Morais Ribeiro G, Damaceno Emiliano J, Campolina Fonseca A, de Oliveira Botelho L, Couto Castro L, Torres da Silva A, et al. Anatomical variation of the saphenous nerve path: A case report. Morphologie. 2022 Sep;106(354):199-202.
13. Schmidt CK, Iwanaga J, Yilmaz E, Wilson C, Oskouian RJ, Tubbs RS. Absence of the Lumbosacral Trunk. Cureus. 2017 Oct 30;9(10):e1809.
14. Olewnik L, Zielinska N, Ruzik K, Podgorski M, Koptas K, Karauda P, et al. Morphological variability of the piriformis muscle. Folia Morphol (Warsz). 2024;83(4):874-85.
15. Smoll NR. Variations of the piriformis and sciatic nerve with clinical consequence: a review. Clin Anat. 2010 Jan;23(1):8-17.
16. Zapletal J, Nanka O, Halaska MJ, Maxova K, Hajkova Hympanova L, Krofta L, et al. Anatomy of the pudendal nerve in clinically important areas: a pictorial essay and narrative review. Surg Radiol Anat. 2024 Feb;46(2):211-22.
17. Ozcivit Erkan IB, Gorgun E. Cadaveric Insights into Pudendal Nerve Variations for Sacrospinous Ligament Fixation: A Case Series. Int Urogynecol J. 2024 Dec;35(12):2385-94.
18. Reynoso JP, De Jesus Encarnacion M, Nurmukhametov R, Melchenko D, Efe IE, Goncharov E, et al. Anatomical Variations of the Sciatic Nerve Exit from the Pelvis and Its Relationship with the Piriformis Muscle: A Cadaveric Study. Neurol Int. 2022 Oct 31;14(4):894-902.
19. Jha AK, Baral P. Composite Anatomical Variations between the Sciatic Nerve and the Piriformis Muscle: A Nepalese Cadaveric Study. Case Rep Neurol Med. 2020;2020:7165818.