The lesser trochanter is a posteromedial femoral projection where the iliopsoas muscle attaches.
The lesser trochanter is a conical, posteromedially positioned bony prominence located at the junction of the femoral neck and shaft on the proximal femur. Though smaller than the greater trochanter, it serves as a crucial anatomical landmark and a site of major muscular attachment. Functionally, it acts as a lever for hip flexion and contributes to stability of the femur during gait and movement. Despite its deep location, the lesser trochanter has important clinical relevance, especially in hip fractures and muscular avulsion injuries.
The lesser trochanter is a pyramidal projection composed of dense cortical bone, located inferior and medial to the femoral neck. It is typically more prominent in males than females and varies in size with muscle development and activity level. The apex of the trochanter is often slightly rounded and angled posteromedially toward the body’s midline.
The lesser trochanter lies just inferior to the femoral neck and medial to the shaft. It is situated opposite the greater trochanter on the posterior side of the femur. Anatomically, it is located at the junction where the femoral shaft transitions into the neck, within the proximal metaphyseal region. It is deeply embedded within the musculature of the thigh and pelvis and is not palpable externally.
The primary role of the lesser trochanter is to serve as the insertion site for the iliopsoas muscle, which is the strongest hip flexor. Through this insertion, it contributes to several critical functions:
The only muscle that inserts directly into the lesser trochanter is the iliopsoas muscle, which is composed of the psoas major and the iliacus muscles.
Muscle | Origin | Insertion | Action |
---|---|---|---|
Iliopsoas | Psoas major: T12–L5 vertebral bodies Iliacus: Iliac fossa |
Lesser trochanter of femur | Hip flexion and slight lateral rotation |
Due to its deep location, the lesser trochanter is not directly visible or palpable, but it is intimately related to surrounding neurovascular and muscular structures:
The lesser trochanter receives vascular branches from surrounding arteries that also supply the proximal femur:
The lesser trochanter itself is not directly innervated, but the iliopsoas muscle that inserts here receives innervation from the femoral nerve (L2–L4). The overlying capsule and periosteum receive sensory innervation via articular branches from the femoral and obturator nerves, which can refer pain from nearby injuries.
The lesser trochanter develops from a separate secondary ossification center. This center appears around ages 11–13 and typically fuses with the shaft of the femur by age 16–17. It forms under the influence of traction forces exerted by the iliopsoas muscle.
The lesser trochanter is visible on standard pelvic and hip radiographs as a radiopaque protuberance on the medial aspect of the proximal femur. It is best visualized in the frog-leg lateral view.