mammals Mammals () are a group of vertebrate animals constituting the class Mammalia (), characterized by the presence of mammary glands which in females produce milk for feeding (nursing) their young, a neocortex (a region of the brain), fur o ...

including

humans" \n\n\n\n\nThe robots exclusion standard, also known as the robots exclusion protocol or simply robots.txt, is a standard used by websites to indicate to visiting web crawlers and other web robots which portions of the site they are allowed to visi ...

, the medial surface of the

greater trochanter The greater trochanter of the femur is a large, irregular, quadrilateral eminence and a part of the skeletal system. It is directed lateral and medially and slightly posterior. In the adult it is about 2–4 cm lower than the femoral head.Stan ...

has at its base a deep depression bounded posteriorly by the intertrochanteric crest, called the trochanteric fossa. This fossa is the point of insertion of four muscles. Moving from the inferior-most to the superior-most, they are: the tendon of the

obturator externus The external obturator muscle, obturator externus muscle (; OE) is a flat, triangular muscle, which covers the outer surface of the anterior wall of the pelvis. It is sometimes considered part of the medial compartment of thigh, and sometimes c ...

muscle, the obturator internus, the superior gemellus and inferior gemellus. The width and depth of the trochanteric fossa varies taxonomically.Gray's AnatomyNetter 2003Romer 1956 In

reptiliomorphs Reptiliomorpha (meaning reptile-shaped; in PhyloCode known as ''Pan-Amniota'') is a clade containing the amniotes and those tetrapods that share a more recent common ancestor with amniotes than with living amphibians (lissamphibians). It was def ...

such as Seymouria or Diadectes and basal reptiles such as Pareiasaurus, the trochanteric fossa (also known as the intertrochanteric fossa) is a very large depression on the ventral/posterior side of the femur. It is bounded medially by the internal trochanter (also known as the lesser trochanter), laterally by the posterior branch of the ventral ridge, and inferiorly by the convergence of the anterior and posterior branches of the ventral ridge and the adductor ridge. In these taxa, the trochanteric fossa is the insertion point for the puboischiofemoralis externus muscle. In

turtle Turtles are an order of reptiles known as Testudines, characterized by a special shell developed mainly from their ribs. Modern turtles are divided into two major groups, the Pleurodira (side necked turtles) and Cryptodira (hidden necked t ...

s, the intertrochanteric fossa is bounded anteriorly by the trochanter minor (sometimes called the lesser trochanter) and posteriorly by the trochanter major (sometimes called the greater trochanter; neither of these structures is likely homologous to the greater or lesser trochanter in mammals). Often, the intertrochanteric fossa is small and shallow due to the expansion of the two trochanters. In

lepidosaurs The Lepidosauria (, from Greek meaning ''scaled lizards'') is a subclass or superorder of reptiles, containing the orders Squamata and Rhynchocephalia. Squamata includes snakes, lizards, and amphisbaenians. Squamata contains over 9,000 specie ...

, the intertrochanteric fossa is shallow but broad. It is bounded medially by the internal/lesser trochanter and anterior branch of the ventral femoral ridge, and often less distinctly bounded laterally as the greater trochanter and posterior branch of the ventral ridge are highly reduced or absent. In archosaurs and especially in

dinosaur Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Triassic period, between 243 and 233.23 million years ago (mya), although the exact origin and timing of the evolution of dinosaurs is t ...

s, the intertrochanteric fossa is highly developed as both the internal/lesser trochanter and the greater trochanter are better developed. In dinosaurs, this area serves as the insertion point of the iliofemoralis muscles (analogous to the gluteus muscles in mammals).

Notes

References

* * {{Authority control Bones of the lower limb Femur