SUMMARY

The insertion of the gluteus minimus muscle tothe superior aspect of the fibrous capsule of thehip joint, in addition to the anterolateral aspectof the greater trochanter has been reported insurgery, cadavers, and full term fetuses. The pre-sent study aimed to determine whether or notsuch an insertion was present in the SouthIndian fetuses. Seven young-to-full term fetuseswere used. A firm attachment of the gluteusminimus muscle to the hip joint capsule was pre-sent in all the specimens. Sharp dissection wasrequired to separate it from the capsule. Histolo-gical assessment of the junction of the muscle tocapsule revealed that bundles of collagen linkedthe skeletal muscle to the capsule in all cases.Striated muscle fibres became densely collage-nous at the site of attachment to the connectivetissue of the capsule and the dense collagenfibres were arranged in a linear fashion. Func-tional role and clinical anatomy of the capsularattachment are presented.

Key words: Gluteus minimus – Impingementsyndrome – Hip joint

INTRODUCTION

Detached slips may connect the gluteus minimusmuscle with the tensor fascia latae, superiorgamellus, vastus lateralis, gluteus medius, piri-formis, or the capsule of the hip joint (Macalis-

ter, 1875; Le Double, 1897; Bergman et al., 1988;Salmons, 1995; Walters et al., 2001). During sur-gery on the adults, an insertion of the gluteusminimus into the superior aspect of the fibrouscapsule of the hip joint was noted, in addition tothe classic anterolateral aspect of the greater tro-chanter (Hardinge, 1982; Walters et al., 2001). Inthe Black, Caucasian and mixed racial origincadavers, a firm attachment of gluteus minimusto the hip joint capsule was present; this attach-ment was also present in Black term fetuses; his-tological assessment of the junction of muscle tocapsule revealed intramuscular tendons firmlyanchoring the muscle to the capsule in all cases,confirming its insertion into the capsule. A ten-dinous insertion to the capsule was alsodemonstrated in the term fetuses. Capsularattachment is a normal insertion and not a varia-tion (Walters et al., 2001). The purpose of thepresent study was to determine whether or notsuch an insertion was present in the SouthIndian fetuses.

MATERIALS AND METHODS

Seven young-to-full term fetuses from the SouthIndian state of Tamil Nadu were used. Skin andfasciae were removed and the gluteus maximusmuscle was divided midway and reflected. Thegluteus medius muscle was separated from thegluteus minimus muscle, divided midway andreflected. The gluteus minimus muscle wasexposed. Its muscle belly was elevated from itsorigin from the gluteal surface of the coxal bone

SHORT REPORT Eur J Anat, 7 (3): 135-137 (2003)

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Gluteus minimus muscle: insertion to hip jointcapsule in South Indian fetuses

S. Rabi and S. VettivelDepartment of Anatomy, Christian Medical College, Vellore, India

Correspondence to:Dr. Suganthy Rabi. Department of Anatomy, Christian Medical College, Vellore 632 002, India.Phone: 0091 0416 2262603 ext. 4245 / 2260545; Fax 0091 416 2262788E-mail: suganthyrabi@cmcvellore.ac.in

Submitted: April 25, 2003Accepted: October 10, 2003

by blunt dissection up to the level of the hipjoint capsule, where the insertion of its deepmuscle fibres into the superior aspect of the jointcapsule was examined. Its tendinous insertion tothe anterolateral ridge of the greater trochanterwas then elevated, and the tendon was mobili-zed proximally up to the level of the joint cap-sule and its attachment to the capsule was exa-mined. Tissues taken from the junction of themuscle and tendon with the capsule were exa-mined histologically using Verhoeff’s and VanGiesen’s stains.

RESULTS

The deep muscle fibres of the muscle belly ofthe gluteus minimus were firmly inserted intothe superior aspect of the hip joint capsule(Fig. 1). The lower edge of the aponeurosisand the deep surface of the muscle at the ten-don of insertion were firmly attached to thecapsule. This attachment in the fetuses was notby any separate slip of the muscle. A firmattachment of the gluteus minimus muscle tothe hip joint capsule was present in all the spe-cimens dissected. Sharp dissection was requi-red to separate it from the capsule. When thefetus was lifted by the gluteus minimus, theattachment was firm enough to suspend and

bear the fetus. Histological assessment of thejunction of the muscle to the capsule revealedthat bundles of collagen of the intramusculartendons linked the skeletal muscle to the cap-sule in all cases (Fig. 2). Striated muscle fibresbecame densely collagenous at the site ofattachment to the connective tissue of the cap-sule and the dense collagen fibres were arran-ged in a linear fashion.

DISCUSSION

Attachment to the hip capsule was thought to bevia detached slips connecting the gluteus mini-mus muscle with the capsule of the hip joint andan aberration (Bergman et al., 1988) and anexpansion to the coxal capsule (Salmons, 1995).The attachment to the capsule may appear as anaccessory muscle under cover of the main mass(Bergman et al., 1988). Our results clearly shownthat the firm attachment of the main mass of thegluteus minimus, additionally to the hip jointcapsule, is a normal insertion and not a racialvariation, not a developmental change, not anage-related change, or not a postnatal hip jointfunction-related acquired change but a normalinsertion. On the contrary, the absence of thisinsertion would be a variation (Walters et al.,2001).

S. Rabi and S. Vettivel

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Fig. 1.- Junction of gluteus minimus with hip joint capsule in a mid-term fetus. (Gluteus maximus and medius removed). MIN: gluteusminimus; C: hip joint capsule; Arrow: insertion of deep muscle fibres of gluteus minimus into the capsule.

The linear arrangement of the dense collage-nous bundles at the junction of gluteus minimusmuscle to the capsule suggests a mechanicalfunction. The tendinous insertion to the capsule,demonstrated histologically in all the youngerand older fetuses, suggests that the insertion andcollagen bundles are not a phenomenon acqui-red in later life (Walters et al., 2001).

The capsular attachment is responsible andnecessary for retracting the capsule during hipjoint activity to prevent entrapment of the capsu-le (Walters et al., 2001), as in the shoulder, elbow,and knee joints, during muscle dysfunction ordyssynchronous muscle activity such as musclefatigue (Walters et al., 2001). Probably, the capsu-lar attachment also helps in the supportive actionof the gluteus minimus on the pelvis so that thecomponents of the hip joint are in their usual rela-tion when the contralateral foot is raised.

REFERENCES

BERGMAN RA, THOMPSON SA, AFIFI AK, SAADEH FA (1988).Compendium of Human Anatomic Variation. Urban &Schwarzenberg, Baltimore, pp 23.

HARDINGE K (1982). The direct lateral approach to the hip. JBone Joint Surg, 64B: 17-19.

LE DOUBLE AF (1897). Traite des variations du systeme mus-culaire de l’homme et de leur signification an point del’ anthropologie zoologique. Vol. 2. Librarie C. Rein-wald, Schleicher Freres, Paris, pp 226-227.

MACALISTER A (1875). Additional observations on muscularanomalies in human anatomy (3rd series) with a catalo-gue of the principal muscular variations hitherto publis-hed. Transactions of the Royal Irish Academy, 25: 1-134.

SALMONS S (1995). Muscles. In: Williams PL (ed). Gray’s Ana-tomy. Churchill Livingstone, Edinburgh, pp 876-877.

WALTERS J, SOLOMONS M and DAVIES J (2001). Gluteus mini-mus: observations on its insertion. J Anat, 198: 239-242.

Gluteus minimus muscle: insertion to hip joint capsule in South Indian fetuses

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Fig. 2.- Histology of junction of gluteus minimus with hip joint capsule in a mid-term fetus. M: skeletal muscle of gluteus minimus; T: linearcollagen fibres of intermuscular tendons; C: connective tissue of capsule. Verhoeff and Van Giesen staining. x 88.