Muscles and Muscle Action Lower Extremities

Muscles that Move… The Lower Extremities: The Coxal joint/thigh Thigh muscles that move the knee joint/leg Leg muscles Intrinsic muscles of the foot

The Muscles of the Coxal Joint/Thigh Anterior Thigh Compartment (Thigh Flexors) Medial Thigh Compartment (Thigh Adductors) Lateral Thigh Compartment (Thigh Abductors) Gluteal Group Deep Muscles of the Gluteal Region (Lateral Thigh Adductors) Posterior Thigh (Hamstring) Compartment (Thigh Extensors and Leg Flexors)

Muscles of the Anterior Thigh Compartment (thigh flexors) Psoas Major Flexes and laterally rotates thigh Iliacus Flexes and laterally rotates thigih Sartorius Flexes thigh and rotates thigh laterally; flexes leg and rotates leg medially Rectus Femoris Extends leg; flexes thigh

Muscles of the Medial Thigh Compartment (thigh adductors) Adductor Longus Adducts thigh; flexes thigh Adductor Brevis Adducts thigh Gracilis Adducts and flexes thigh; flexes leg Pecineus Adducts thigh; flexes leg Adductor Magnus Adducts thigh; adductor part of muscle flexes thigh; hamstring part of muscle extends and laterally rotates thigh Obturator Externus Laterally rotates thigh

Muscles of the Lateral Thigh Compartment (thigh abductor) Tensor Fasciae Latae Abducts thigh’ medially rotates thigh

Muscles of the Gluteal Group Gluteus Maximus Extends thigh; laterally rotates thigh Gluteus Medius Abducts thigh; medially rotates thigh Gluteus Minimus Abducts thigh; medially rotates thigh

Muscles of the Deep Gluteal Region (lateral thigh rotators) Piriformis Laterally rotates thigh Superior Gemellus Laterally rotates thigh Obturator Internus Laterally rotates thigh Inferior Gemellus Laterally rotates thigh Quadratus Femoris Laterally rotates thigh

Muscles of the Posterior Thigh (hamstring) Compartment Biceps Femoris Extends thigh (long head only); flexes leg (both long head and short head); laterally rotates leg Semimembranosus Extends thigh and flexes leg; medially rotates leg Semitendinosus Extends thigh and flexes leg; medially rotates leg

The Thigh Muscles That Move the Knee Joint/Leg Leg Extensors Quadriceps Femoris Rectus Femoris Extends leg; flexes thigh Vastus Intermedius Extends leg Vastus Lateralis Extends leg Vastus Medius Extends leg Leg Flexors Sartorius Flexes thigh and rotates thigh laterally; flexes leg and rotates thigh medially Gracilis Flexes and adducts thigh; flexes leg Biceps Femoris Extend thigh and flex leg; rotate leg laterally Semimembranosus Extend thigh and flex leg; rotate leg medially Semitendinosus Extend thigh and flex leg; rotates leg medially

Leg Muscles Anterior Compartment (dorsiflexors and toe extensors) Lateral Compartment (evertors and weak plantar flexors) Posterior Compartment (plantar flexors, flexors of the leg and toes) Superficial Layer Deep Layer

Leg Muscles: Anterior Compartment Extensor Digitorum Longus Extends toes 2-5 Extensor Hallucis Longus Extends great toe; dorsiflexes foot Fibularis Tertius Dorsiflexes and weakly everts foot Tibialis Anterior Dorsiflexes foot; Inverts foot

Leg Muscles: Lateral Compartment Fibularis Longus Everts foot, weak plantar flexor Fibularis Brevis Everts Foot, weak plantar flexor

Leg Muscles: Posterior Compartment Superficial: Triceps Surae Gastrocnemius Flexes leg; plantar flexes foot Soleus Plantar flexes foot Plantaris Weak leg flexor and plantar flexor Deep: Flexor Digitorum Longus Plantar flexes foot; flexes MP, PIP, and DIP joints of toes 2-5 Flexor Hallucis Longus Plantar flexes foot; flexes MP and IP joints of great toe Tibialis Posterior Plantar flexes foot; inverts foot Poplitus Flexes leg; medially rotates tibia to unlock the knee

Intrinsic Muscles of the Foot Dorsal Surface (toe extensors) Plantar Surface (toe flexors, adductors, abductors) Layer 1 (superficial Layer 2 (Deep) Layer 3 (Deeper) Layer 4 (Deepest)

Intrinsic Muscles of the Foot Dorsal Surface Extensor Hallucis Brevis Extends MP joint of great toe Extensor Digitorum Brevis Extends MP and PIP joints of toes 2-4

Intrinsic Muscles of the Foot Plantar Surface Layer 1 (superficial) Flexor Digitorum Brevis Flexes MP and PIP joints of toes 2-5 Abductor Hallucis Abducts great toe Abductor Digiti Minimi Abducts toe 5

Intrinsic Muscles of the Foot Plantar Surface Layer 2 (Deep) Quadratus Plantae Pulls on flexor digitorum longus tendons to flex toe 2-5 Lumbricals Flexes MP joints and extends PIP and DIP joints of toes 2-5

Intrinsic Muscles of the Foot Plantar Surface Layer 3 (Deeper) Adductor Hallucis Adducts great toe Flexor Hallucis Brevis Flexes MP joint of great toe Flexor Digiti Minimi Brevis Flexes MP joint of toe 5

Intrinsic Muscles of the Foot Plantar Surface Layer 4 (Deepest) Dorsal Interossei Abducts toes Plantar Interossei Adducts toes