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HIP MUSCLES
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In fish, hypaxial
musculature allows for movement of the pelvic fin as it does the pectoral
fin. |
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SHARK |
LUNGFISH |
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TENSOR FASCIA LATA Early tetrapods
possess an iliofemoralis muscle which separated
to form the tensor fascia latae, pyriformis,
and gluteus muscles of mammals (Kardong, p.
387). The gluteus maximus
isn’t well separated from tensor fascia latae
and caudofemoralis in many animals (Hartman, 1933, p. 151). |
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CHICKEN |
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CAT |
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GOAT |
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COW |
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MONKEY |
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GLUTEAL The gluteal muscles abduct the hip. In humans, the gluteus maximus
has been modified to become a hip extensor. |
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FROG |
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The iliofemoralis muscle in turtles is homologous
to mammalian gluteal muscles |
ALLIGATOR |
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OPOSSUM |
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CAT |
CAT |
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GOAT |
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SHEEP |
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COW |
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PIG |
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MONKEY |
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The primitive condition of the gluteus maximus (gluteus superficialis)
which is retained in prosimians and many In In gibbons, the gluteus superficialis originates from the sacrum and the first coccygeal vertebrae and the insertion can extend to the femoral
midpoint. In African apes, the
distal insertion of the superficialis can extend
two thirds down the length of the femur, and often farther. In chimps, the medius
is larger than the superficialis but in gorillas
the two are similar in size. In
orangutans, the posterior portion of the superficialis
is reduced as is the distal extension of its insertion (Stern, 1972). In humans, the gluteus maximus
is unique in its strong origin from the ilium
in addition to origins on the sacrum and coccyx (although a tendon does
reach the ilium in siamangs). Humans are also unique in the enlarged origin
from the fascia over the multifidus muscle. The majority of the muscle does not extend farther
distally than one fourth the length of the femur. The cranial portion of the gluteus maximus is much larger contributing to for the increased size
of the muscle in humans (and perhaps entirely responsible for the size
increase), which is more than twice the size of the gluteus medius. This condition is unique in primates (Stern,
1972). The gluteus maximus
is not active in a standing stance and some individuals do not use it
when walking. It has no specific
role in walking and walking may be unimpaired by its paralysis. The muscle may play a more important role in
jogging and running and it may be this locomotion style which drove the
modification of the muscle in human ancestors.
The gluteus maximus is an extensor of
the thigh in both humans and chimps, but its modifications in humans increase
its efficiency, especially in running.
The gluteus maximus muscle,
and its cranial portion specifically, are important in forceful abduction
and in maintaining stability when the body is supported on one leg (Stern,
1972). There is no single major feature which enabled
bipedality in hominids but rather a combination
of smaller changes (Robinson, 1972). Perhaps the first of the changes which allowed
bipedality was a shift in the center of gravity
from the midtrunk (as in chimps) to the pelvic
cavity (as in humans). In chimps
the gluteus medius functions as an extensor
unlike the gluteus medius in humans. The shortening of the ischium
was important in modifying the line of function of hamstring muscles (Robinson,
1972). The muscles of Australopithecus afarensis
were not as efficient at supporting bipedal locomotion as those of
modern humans (Wang, 2004c). The gluteus medius
in chimps (the largest gluteal muscle) is primarily
an extensor rather than an abductor, as it is in humans. As a result, chimps lack lateral balance control.
In humans, the change in the position of the iliac blades allowed
the gluteus medius (and minimis)
to provide effective lateral balance which is lacking in chimps.
While both Paranthropus and
Australopithecus were bipedal, Australopithecus had a short ischium, more elongated leg and a more human like foot, suggesting
it was more adapted for running (Robinson, 1972) |
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HUMAN |
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