71 - Iliacus Variations Found Through Five Years of Gross Anatomy Dissections in the Physical Therapy Anatomy Laboratory

Poster Board Number: 71
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Co-authors:

Philip Fabrizio - Associate Professor, PCOM Georgia

Abstract Body : Introduction & Objective: The iliacus muscle (IM) typically originates from the iliac fossa, inserts into the lesser trochanter of the femur with the psoas major to function as the primary hip flexor muscle and is innervated by the femoral nerve. Five IM variations have been identified from cadaver dissections over five years in the physical therapy anatomy laboratory and are described here. The purposes of this study were: 1) to catalog variations of IM while performing dissections on human cadavers; 2) to describe differences in IM variations discovered; 3) to determine which variations present a novel muscular arrangement.

Materials & Methods: Routine and fine dissection techniques were used to reveal the posterior wall of the abdominal cavity allowing observation of the iliacus IM. Forty human cadavers, age range 45-90 years, were dissected over five years from 2018 to 2023 in the physical therapy anatomy laboratory.

Results: Five IM variations were discovered.

1. Thin muscular slip of right IM originated from superior, central portion of iliac fossa and converging with femoral nerve superior to ilioinguinal ligament.


2. Muscular slip of right IM from supero-lateral iliac fossa spanned halfway to lumbar spine, crossed over femoral nerve slightly superior to ilioinguinal ligament, and inserted into psoas major.


3. Thin muscular slip from right IM originated at medial superior iliac fossa, crossed over femoral nerve superior to ilioinguinal ligament, and inserted with iliopsoas.


4. Muscular slip of right IM from supero-lateral half of iliac fossa, crossed over femoral nerve, and inserted into iliacus inferior to ilioinguinal ligament.


5. Muscular slip of right IM originated at medial half of iliac fossa, crossed femoral nerve superior to ilioinguinal ligament, and inserted with iliopsoas muscle.

Conclusion: Variations of the IM are rare. Based on the five variations found, it could be predicted that nerve impingement or entrapment is a possible consequence. Specifically, a muscular slip of the iliacus variation crossing over the femoral nerve could cause inflammation and compression of the nerve.

Significance/Implication: Symptoms from a compressed nerve could include the decrease or loss of sensory function in the medial lower extremity. Decrease or loss of motor function would occur to the muscles innervated by the femoral nerve below the sight of impingement including the quadriceps, sartorius and possibly the pectineus. Nerve conduction studies could be used for testing. Because IM variations are so rare, imaging could be misinterpreted as a mass or some other diagnosis other than a muscle variation.