Abdominal Wall Muscles

The double-headed accessory iliacus muscle: a case report

“…These were classified by Aleksandrova et al based on their relationship with the FN [1]. This classification comprises type A, where the muscular mass of the IM from the anterior and middle part was replaced by fibrous slips [1]; type B, with complete separation of IM and psoas major [8,13,26]; type C, with complete fusion of IM and psoas major with typical course of FN [9]; type D, with highly originated muscular slips that include extremely rare reports of psoas tertius and psoas quartus [5,11,27]; type E, with an iliacus minor -a muscle arising from the anterior inferior iliac spine of the ilium and inserting onto the anterior trochanteric line, and the ilio-capularis, with a similar originanterior trochanteric line and insertion onto the ilio-femoral ligament [2,29]; type F, with deep and superficial layers of IM [10,16]; type G, with large muscular slips of iliacus [21];…”

“…One of those is the occurrence of the accessory iliacus muscle (AIM). In previously presented cases, this structure was usually described as a slim muscular slip arising from the middle third of inner lip of iliac crest; it was distinguishable from iliacus muscle mass and traced the iliopsoas muscle complex distally onto its site of insertion: the lesser trochanter of the femur [6,26].…”

The morphological variability of the pelvic girdle muscles: a potential trap during ultrasound

“…The psoas minor muscle is a small, flat, fusiform muscle that occurs in 30 to 60% of the population [30,69]. It usually originates from the twelfth thoracic vertebra, first lumbar vertebra and the intervertebral disc between them; it forms a short and slender muscular belly that descends inferiorly and becomes a long tendon that inserts to pectineal pubic line, iliopectineal eminence and the iliac fascia [54].…”

“…The muscle might be totally replaced by a tendon, or the tendinous portion might be exceptionally long, i.e. with the tendinous part comprising more than 57% of the total muscle length [69]. There are also mentions of alternative insertion sites including the inguinal ligament, neck of the femur or lesser trochanter [21].…”

A three-headed psoas major muscle: a case report

“…Numerous morphological variations have been reported among muscles from different compartments of human body [10,16,17,30], including the iliopsoas muscle complex [1,3,7,24,28]. There are reports about complete separation or fusion of its components [23], presence of accessory muscular slips [1,21] or accessory muscles, such as the ilio-capularis [1,23], accessory iliacus [3], iliacus minimus [25], psoas quartus [18,24,28] or psoas tertius [9] and even the presence of an accessory iliopsoas muscle complex [7,26]. However, on its own, the PM muscle seems a rather constant structure that does not present much morphological variability.…”