The lesser trochanter is a conical posteromedial bony projection of the

femoral shaft The body of femur (or shaft of femur) is the almost cylindrical, long part of the femur. It is a little broader above than in the center, broadest and somewhat flattened from before backward below. It is slightly arched, so as to be convex in front ...

. it serves as the principal insertion site of the iliopsoas muscle.

Structure

The lesser trochanter is a conical posteromedial projection of the

shaft Shaft may refer to: Rotating machine elements * Shaft (mechanical engineering), a rotating machine element used to transmit power * Line shaft, a power transmission system * Drive shaft, a shaft for transferring torque * Axle, a shaft around whi ...

of the

femur The femur (; ), or thigh bone, is the proximal bone of the hindlimb in tetrapod vertebrates. The head of the femur articulates with the acetabulum in the pelvic bone forming the hip joint, while the distal part of the femur articulates ...

, projecting from the posteroinferior aspect of its junction with the femoral neck. The summit and anterior surface of the lesser trochanter are rough, whereas its posterior surface is smooth. From its apex three well-marked borders extend: * two of these are above ** a medial continuous with the lower border of the femur neck ** a lateral with the intertrochanteric crest * the inferior border is continuous with the middle division of the linea aspera

Attachments

The summit of the lesser trochanter gives insertion to the tendon of the psoas major muscle and the iliacus muscle; the lesser trochanter represents the principal attachment of the iliopsoas.

Anatomical relations

The intertrochanteric crest (which demarcates the junction of the femoral shaft and neck posteriorly) extends between the lesser trochanter and the greater trochanter on the posterior surface of the femur.

Clinical significance

The lesser trochanter can be involved in an

avulsion fracture An avulsion fracture is a bone fracture which occurs when a fragment of bone tears away from the main mass of bone as a result of physical trauma. This can occur at the ligament by the application of forces external to the body (such as a fall ...

Other animals

Paleontology

The position of the lesser trochanter close to the head of the

is one of the defining characteristics of the Prozostrodontia, which is the

clade A clade (), also known as a monophyletic group or natural group, is a group of organisms that are monophyletic – that is, composed of a common ancestor and all its lineal descendants – on a phylogenetic tree. Rather than the English ter ...

cynodont The cynodonts () (clade Cynodontia) are a clade of eutheriodont therapsids that first appeared in the Late Permian (approximately 260 mya), and extensively diversified after the Permian–Triassic extinction event. Cynodonts had a wide varie ...

s including

mammal 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 ...

s and their closest non- mammaliform relatives. It was erected as a

node-based taxon Phylogenetic nomenclature is a method of nomenclature for taxa in biology that uses phylogenetic definitions for taxon names as explained below. This contrasts with the traditional approach, in which taxon names are defined by a '' type'', which ...

as the least inclusive clade containing '' Prozostrodon brasiliensis'', '' Tritylodon langaevus'', '' Pachygenelus monus'', and '' Mus musculus'' (the house mouse). All living mammals have a lesser trochanter, whose size, shape, and position is distinctive to their species.

Additional images

File:Gray245.png, Right femur. Posterior surface. File:Gray339.png, Right hip-joint from the front. File:Gray343.png, Capsule of hip-joint (distended). Posterior aspect. File:Slide2DAD.JPG, Hip joint. Lateral view. Lesser trochanter File:Slide1BIBI.JPG, Muscles of Thigh. Anterior views.

References

External links

* * (, ) {{Authority control Bones of the lower limb Femur