192 Anatomy & Physiology Essentials Copyright Goodheart-Willcox Co., Inc. vastus medialis, and vastus intermedius, which lies under the rectus femoris. These four muscles are often referred to as a group because they all attach to the tibia via the patellar tendon. Collectively, they are the prime extensors of the leg at the knee. Muscles Acting at the Knee Notice the muscle groups on the anterior side and posterior side of the thigh, described in Figure 6.23 and shown in Figure 6.24. The anterior group, the quadriceps, includes the rectus femoris, vastus lateralis, Muscles of the Lower Limb Hip Muscles Muscle Origin Insertion Primary Functions Gluteus maximus sacrum and iliac gluteal tuberosity of femur extension and lateral rotation of leg Gluteus medius posterior ilium greater trochanter of femur abduction and medial rotation of leg Iliopsoas (fusion of iliacus and psoas muscles) iliac fossa and sacrum, 12th thoracic and all lumbar vertebrae lesser trochanter of femur flexion of leg at hip Adductor muscles magnus longus brevis pubis linea aspera of femur adduction and medial rotation of leg Sartorius anterior superior iliac spine proximal tibia assists with flexion and lateral rotation of leg Knee Muscles Muscle Origin Insertion Primary Functions Quadriceps: rectus femoris anterior inferior iliac spine tibia via patellar tendon extension of leg at knee Quadriceps: vastus lateralis greater trochanter and linea aspera tibia via patellar tendon extension of leg at knee Quadriceps: vastus intermedius anterior femur tibia via patellar tendon extension of leg at knee Quadriceps: vastus medialis linea aspera tibia via patellar tendon extension of leg at knee Hamstrings: semitendinosus ischial tuberosity proximal medial tibia flexion of leg at knee medial rotation Hamstrings: semimembranosus ischial tuberosity proximal medial tibia flexion of leg at knee medial rotation Hamstrings: biceps femoris long head originates on ischial tuberosity short head originates on linea aspera lateral condyle of tibia and head of fibula flexion of leg at knee lateral rotation Ankle/Foot Muscles Muscle Origin Insertion Primary Functions Gastrocnemius posterior medial and lateral femoral condyles calcaneus (heel bone) via Achilles tendon plantar flexion of foot, flexion of leg at knee Soleus fibula and tibia calcaneus via Achilles tendon plantar flexion of foot Tibialis anterior tibia first cuneiform and first metatarsal in foot dorsiflexion and inversion of foot Extensor digitorum longus lateral condyle of tibia and proximal 3/4 of fibula phalanges of toes 2–5 dorsiflexion, eversion, toe extension Fibularis longus brevis tertius fibula metatarsals plantar flexion, eversion Figure 6.23 Goodheart-Willcox Publisher