7
Muscles in the Anterior Compartment of the Thigh
The muscles of the anterior compartment of the thigh are a group of muscles that (mostly)
act to extend the lower limb at the knee joint.
They are collectively innervated by the femoral nerve (L2-L4), and recieve arterial supply
from the femoral artery.
Iliopsoas
The iliopsoas is comprised of two separate muscles; the psoas major and iliacus.
These muscles arise in the pelvis and pass under the inguinal ligament into the anterior
compartment of the thigh – where they form a common tendon.
Unlike many of the anterior thigh muscles, the iliopsoas does not perform extension of the
leg at the knee joint.
Attachments: The psoas major originates from the lumbar vertebrae, and the iliacus
originates from the iliac fossa of the pelvis. They insert together onto the lesser
trochanter of the femur.
Actions: Flexion of the the thigh at the hip joint.
Innervation: The psoas major is innervated by anterior rami of L1-3, while the iliacus is
innervated by the femoral nerve.
Quadriceps Femoris
The quadriceps femoris consists of four individual muscles – the three vastus muscles and
the rectus femoris. It forms the main bulk of the anterior thigh, and is one of the most
powerful muscles in the body.
The four muscles collectively insert onto the patella via the quadriceps tendon. The patella,
in turn, is attached to the tibial tuberosity by the patella ligament.
Vastus Lateralis
Proximal attachment: Originates from the greater trochanter and the lateral lip of
linea aspera of the femur.
Actions: Extension of the knee joint. It has a secondary function of stabilising the
patella.
Innervation: Femoral nerve.
Vastus Intermedius
Proximal attachment: Originates from the anterior and lateral surfaces of the femoral
shaft.
Actions: Extension of the knee joint. It has a secondary function of stabilising the
patella.
Innervation: Femoral nerve.
Vastus Medialis
Proximal attachment: Originates from the intertrochanteric line and medial lip of the
linea aspera of the femur.
Actions: Extension of the knee joint. It has a secondary function of stabilising the
patella.
Innervation: Femoral nerve.
