Original Editor - Mariam Hashem Top Contributors - Olajumoke Ogunleye and Mariam Hashem

Description[edit | edit source]

  • Iliocappsularis muscle is sometimes referred to as the iliacus minor or ilioinfratrochantericus [1]. This muscle hasn't received much attention in the literature and some authors refer to it as the accessory iliacus, as it cannot be separated from it.
  • It lies beneath the rectus femoris and to the lateral right of the iliacus[2]. It is considered an important landmark in surgery in patients with symptomatic dysplastic hips[1].
    The cadaver dissection shows the anterior aspect of the hip. The iliocapsularis muscle (IC) originates from the anterior-inferior iliac spine (AIIS) and the anterior hip capsule (C). Its insertion is located just distal to the lesser trochanter (LT).

Origin[edit | edit source]

  • Inferior border of the anterior inferior iliac spine (AIIS).
  • The anteromedial hip capsule[1].

Insertion[edit | edit source]

Approximately 1.5 cm distal to the lesser trochanter[1].

Nerve[edit | edit source]

Femoral Nerve (L2-4 root)[3].

Artery[edit | edit source]

  • Profunda femoral artery, a branch of the femoral artery.
  • Lateral femoral circumflex artery, a branch of the profunda femoral artery[1].

Function[edit | edit source]

The true function of iliocapsularis remains unknown. However, its anatomy suggests some possible roles such as:

  • Stabilization of the femoral head within dysplastic acetabulum because of its direct anteromedial capsular attachment [4][5].
  • May contribute to the stability of the anterior hip joint[4][5][6].
  • Electromyography study (Lawrenson et al., 2019) shows that iliocapsularis muscle may stabilize the hip joint by tensing the anterior capsule for initiation of flexion during walking[7].
  • The prevention of pinching of the anteromedial part of the capsule between the femoral head and the acetabulum is also attributed to the iliocapsularis due to its attachments to the anteromedial part of the hip capsule[2].

Clinical relevance[edit | edit source]

  • Anterior hip pain with hip flexion might indicate subspine impingement, a condition that arises from a collision between the anterior femoral neck and AIIS with abnormal morphology during hip flexion. Due to its attachment to the AIIS, the iliocapsularis could contribute to new osteophytes formation when a mechanical load is applied through it this point (Wolff’s law) and could be a potential cause of subspine impingement. Therefore, it should be considered in differential diagnosis of hip impingement[2].
  • Loss of function of iliocapsularis, either by atrophy or weakness, can possibly lead to entrapment of the capsule between the joint surfaces[2].
  • Iliocapsularis is also an important land mark for surgeons e.g. Bernese pericapsular osteotomy[2].

References[edit | edit source]

  1. 1.0 1.1 1.2 1.3 1.4 Ward WT, Fleisch ID, Ganz R. Anatomy of the iliocapsularis muscle: Relevance to surgery of the hip. Clinical Orthopedics Related Research 2000;374:278-285.
  2. 2.0 2.1 2.2 2.3 2.4 Sato T, Sato N, Sato K. Review of the Iliocapsularis Muscle and its Clinical Relevance. Anat Physiol 2016;6:237.
  3. D’Costa SU, Ramanathan LA, Madhyastha S, Nayak SR, Prabhu LV, Rai R, Saralaya VV. An accessory iliacus muscle: a case report. Rom J Morphol Embryol. 2008 May;49(3):407-9.
  4. 4.0 4.1 Babst D, Steppacher SD, Ganz R, Siebenrock KA, Tannast M.The Iliocapsularis Muscle: An Important Stabilizer in the Dysplastic Hip. Clinical Orthopaedics and Related Research 2011;469:1728-1734.
  5. 5.0 5.1 Haefeli PC, Steppacher SD, Babst D, Siebenrock KA, Tannast M. An increased iliocapsularis to rectus femoris ratio is suggestive for instability in borderline hips. Clinical Orthopaedics and Related Research 2015;473:3725-3734.
  6. Mashriqi F, D’Antoni AV, Wilson C, Unno F, Lee CB, Mayo K, Tubbs SR. The functional and surgical relevance of the iliocapsularis muscle: an anatomical review. Anatomy 2017;11(3):146–148.
  7. Lawrenson P, Hodges P, Crossley K, Vicenzino B, McGorm M, Semciw A. The effect of altered stride length on iliocapsularis and pericapsular muscles of the anterior hip. Gait & Posture 2019;71:26-31.