A Macroscopic Examination of M. Biceps Femoris and M. Gluteus Maximus in the Orangutan

Abstract

ABSTRACT. The musculature of the hip and thigh in the orangutan has been described previously. Anatomically, there are various descriptions among primates in those structures, in particular, the relationship between M. biceps femoris and M. gluteus maximus, their derivatives, and the muscle segment. However, a detailed innervation system to this ischiofemoral part has not been described, thus there is still uncertainty as to with which muscle it is associated. In this analysis, we examined the gross anatomy of the hip and thigh muscles of the orangutan and chimpanzee, including their innervation. Also, a comparison was made with documented data of other primates. As a result of these observations, it was found that the ischiofemoral part in the orangutan is innervated by the same sciatic nerve branch (the common peroneal nerve) as the long head of M. biceps femoris, but not by the same nerve as M. gluteus maximus. Therefore, the ischiofemoral part is appropriately considered as a part of the long head of M. biceps femoris. It appears that this morphologic feature is an adjustment to the arboreal life of the orangutan. The development of the flexor complex of the thigh is necessary for this arboreal adaptation, resulting in a unique musculature of M. biceps femoris in the orangutan. KEY WORDS: gross anatomy, innervation system, M. biceps femoris, M. gluteus maximus, orangutan.J. Vet. Med. Sci. 70(3): 217-222, 2008 The orangutan (Pongo pygmaeus), the only great ape in Asia, is the only arboreal great ape in the world. It rarely descends to the ground, living most of its life in trees 20-60 m in height. The orangutan moves from branch to branch utilizing all of its limbs in a unique locomotion system called brachiation. It therefore has a distinctive foot structure that adjusts to the type of grip required. It has a plantigrade foot posture, yet only the exterior of the sole touches the ground. When walking on the ground level, it does not stand with its trunk in a vertical position, and moves with its knees flexed and its lower extremities abducted.The musculature of the hip and thigh in the orangutan has been previously described, in particular, the relationship of M. biceps femoris and M. gluteus maximus (M. gluteus superficialis). The muscle, around which the present discussion is centered, arises from the ischial tuberosity and inserts onto the shaft of the femur. Hereafter, this is referred to as the ischiofemoral part. Sonntag [7] referred to this ischiofemoral part as the inferior part of M. gluteus maximus, and thus considered it part of M. gluteus maximus. In recent years, Hamada [2] reported that it is not clear to which muscle this ischiofemoral part belongs (M. gluteus maximus, Sigmon, [6]; M. biceps femoris, Stern, [8]). Tuttle and Cortright [10] described the hip musculature of the orangutan as representing a unique pattern amongst the Hominoidae; the lower portion of the M. gluteus maximus complex is a discrete muscle, M. ischiofemoralis. They demonstrate that the ischiofemoral part of the M. isc...

Foetal development of the human gluteus maximus muscle with special reference to its fascial insertion

“…The gluteus maximus muscle (GMX) is the largest skeletal muscle in the human body. This muscle forms a flexor complex with the biceps femoris in non-human primates [9]. In contrast, the human GMX is characterised by its strong insertion to a thick lateral fibrous band beneath the fascia lata, i.e., the tractus iliotibialis or iliotibial tract [3,5].…”

Linking the proximal tibiofibular joint to hominid locomotion: A morphometric study of extant species

“…The two heads of the m. biceps femoris are fused at their distal insertion in chimpanzees and modern humans but not in Pongo and Gorilla (Ferrero et al, 2012). Kaseda et al (2008) describe the unique morphology of the femoral part of the m. biceps femoris in orangutans and suggests it is an adaptation to arboreal behavior due to similarities with Old World monkeys.…”

Morphogenetic progression of thigh and lower leg muscles during human embryonic development

“…This change would be suitable for humans who have traveled across continents for long periods. There are also differences at the level of individual muscles; for example, gluteus maximus (GM) in humans is attached to the iliotibial ligament, while the GM in quadrupedal animals forms a flexor complex with biceps femoris (Kaseda et al, 2008). The primary role of the GM in quadrupedal animals is to extend the hip joint; in contrast, the human GM plays a significant role in pelvic stability (Gerlach & Lierse, 1990).…”