Muscles of the Lower Limb

Most of the muscles which move the hip joint originate on the pelvis. The important exception is the psoas muscle which originates on the anterolateral vertebral bodies and transverse processes of the upper lumbar vertebrae. The psoas is an important flexor of the hip joint. It is assisted by iliacus which runs from the iliac fossa to the lesser trochanter of the femur. Psoas and iliacus are often referred to collectively as iliopsoas.

Iliopsoas is opposed by gluteus maximus, the strongest extensor of the hip. Gluteus maximus originates on the sacrum and ilium, and inserts on the upper femur. Gluteus medius and gluteus minimus also originate on the sacrum and ilium, but because of their different attachments on the femur they are more important in abduction of the hip. Abduction is also aided by tensor fascia lata which joins the iliotibial band in connecting the pelvis to the lateral head of the tibia. The adductor group, including adductor longus, adductor magnus and gracilis, attach the pubis and ischium to the medial head of the tibia, and so adduct the hip joint. Numerous small, deep muscles help to laterally rotate the thigh. One of these, piriformis, is clinically important because it has the potential to restrict motion of the sacroiliac joint and compress the sciatic nerve.

The longest muscle in the body is sartorius, which runs from the anterior superior iliac spine (ASIS) to the medial head of the tibia. This important muscle therefore flexes and laterally rotates the hip, while flexing the knee. Another long muscle which manipulates both the hip and knee joint is rectus femoris. Acting alone, rectus femoris flexes the hip and extends the knee. Rectus femoris is part of a group of four muscles, known collectively as quadriceps femoris, which can all extend the knee. The other three members of this group are vastus medialis, vastus intermedialis and vastus lateralis. All muscles of the quadriceps femoris group insert on the patella. The quadriceps group is opposed by three muscles known collectively as the hamstrings. These muscles are semimembranosus, semitendinosus and biceps femoris.

The gastrocnemius is the longest muscle of the lower leg. It originates on the femur and crosses the knee and ankle joint to insert, via the Achilles tendon, on the calcaneus. Gastrocnemius is an important plantar flexor, but may also flex or extend the knee depending on the angle of the knee joint. Plantar flexion is assisted by soleus, which runs from the posterior tibia and fibula to the Achilles tendon. Gastrocnemius and soleus are opposed by tibialis anterior which dorsiflexes and inverts the ankle. Eversion of the ankle is accomplished by peroneus longus and peroneus brevis.


English - Japanese Glossary

adductor longus: 長内転筋 (chounaitenkin); adductor magnus: 大内転筋 (dainaitenkin); biceps femoris: 大腿二頭筋 (daitainitoukin); gastrocnemius: ひ腹筋 (hifukukin); gracilis: 薄筋 (hakukin); gluteus maximus: 大殿筋 (daidenkin); gluteus medius: 中殿筋 (chuudenkin); gluteus minimus: 小殿筋 (shoudenkin); iliacus: 腸骨筋 (choukotsukin); iliotibial band: 腸脛靱帯 (choukeijintai); peroneus brevis: 短ひ骨筋 (tanhikotsukin); peroneus longus: 長腓骨筋 (chouhikotsukin); piriformis: 梨状筋 (rijoukin); tensor fascia lata: 大腿筋膜張筋 (daitaikinmakuchoukin); psoas: 腰筋 (youkin); quadriceps femoris: 大腿四頭筋 (daitaishitoukin); rectus femoris: 大腿直筋 (daitaichokkin); sartorius: 縫工筋 (houkoukin); semimembranosus: 半膜様筋 (hanmakuyoukin); semitendinosus: 半腱様筋 (hankenyoukin); soleus: ヒラメ筋 (hiramekin); tibialis anterior: 前脛骨筋 (zenkeikotsukin); vastus intermedialis: 中間広筋 (chuukankoukin); vastus lateralis: 外側広筋 (gaisokukoukin); vastus medialis: 内側広筋 (naisokukoukin)