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10.7: Appendicular Muscles of the Pelvic Girdle and Lower Limbs

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    22333
  • By the end of this section, you will be able to:

    • Identify the appendicular muscles of the pelvic girdle and lower limb
    • Identify the movement and function of the pelvic girdle and lower limb

    The appendicular muscles of the lower body position and stabilize the pelvic girdle, which serves as a foundation for the lower limbs. Comparatively, there is much more movement at the pectoral girdle than at the pelvic girdle. There is very little movement of the pelvic girdle because of its connection with the sacrum at the base of the axial skeleton. The pelvic girdle is less range of motion because it was designed to stabilize and support the body.

    Muscles of the Thigh

    What would happen if the pelvic girdle, which attaches the lower limbs to the torso, were capable of the same range of motion as the pectoral girdle? For one thing, walking would expend more energy if the heads of the femurs were not secured in the acetabula of the pelvis. The body’s center of gravity is in the area of the pelvis. If the center of gravity were not to remain fixed, standing up would be difficult as well. Therefore, what the leg muscles lack in range of motion and versatility, they make up for in size and power, facilitating the body’s stabilization, posture, and movement.

    Gluteal Region Muscles That Move the Femur

    Most muscles that insert on the femur (the thigh bone) and move it, originate on the pelvic girdle. The psoas major and iliacus make up the iliopsoas group. Some of the largest and most powerful muscles in the body are the gluteal muscles or gluteal group. The gluteus maximus is the largest; deep to the gluteus maximus is the gluteus medius, and deep to the gluteus medius is the gluteus minimus, the smallest of the trio (Figure \(\PageIndex{1}\) and Table \(\PageIndex{1}\)).

    anterior view of the superfical pelvic and thigh muscles of the right leg; anterior view of the deep pelvic and thigh muscles of the right leg; posterior view of the pelvic and thigh muscles of the right leg
    Figure \(\PageIndex{1}\): Hip and Thigh Muscles. The large and powerful muscles of the hip that move the femur generally originate on the pelvic girdle and insert into the femur. The muscles that move the lower leg typically originate on the femur and insert into the bones of the knee joint. The anterior muscles of the femur extend the lower leg but also aid in flexing the thigh. The posterior muscles of the femur flex the lower leg but also aid in extending the thigh. A combination of gluteal and thigh muscles also adduct, abduct, and rotate the thigh and lower leg. (Image credit: "Gluteal Muscles that Move the Femur" by Openstax is licensed under CC BY 4.0)

    Table \(\PageIndex{1}\): Gluteal Region Muscles That Move the Femur

    Prime Mover Origin Insertion Movement Target Target Motion Direction
    Iliopsoas group
    Iliacus Iliac fossa; iliac crest; lateral sacrum Lesser trochanter of femur Raises knee at hip, as if performing knee attack; assists lateral rotators in twisting thigh (and lower leg) outward; assists with bending over, maintaining posture Femur

    Thigh: flexion; lateral rotation

    Torso: flexion

    Psoas major Lumbar vertebrae (L1 - L5); thoracic vertebrae (T12) Lesser trochanter of femur Raises knee at hip, as if performing knee attack; assists lateral rotators in twisting thigh (and lower leg) outward; assists with bending over, maintaining posture Femur

    Thigh: flexion; lateral rotation

    Torso: flexion

    Gluteal Group
    Gluteus maximus Dorsal ilium; sacrum; coccyx Gluteal tuberosity of femur; iliotibial tract Lower knee and moves thigh back, as when getting ready to kick a ball Femur Extension
    Gluteus medius Lateral surface of ilium Greater trochanter of femur Opens thighs, as when doing a split Femur Abduction
    Gluteus minimus External surface of ilium Greater trochanter of femur Brings thighs back together Femur Abduction
    Tensor fascia lata Anterior aspect of iliac crest; anterior superior iliac spine Iliotibial tract Assists with raising the knee at hip and opening thighs; maintains posture by stabilizing the iliotibial tract, which connects to the knee Femur Flexion; abduction
    Lateral Rotators
    Inferior gemellus Ischial tuberosity Greater trochanter of femur Twists thigh (and lower leg) outward; maintains posture by stabilizing hip joint Femur Lateral rotation
    Obturator externus Outer surfaces of obturator membrane, pubis, and ischium; margins of obturator foramen Trochanteric fossa of posterior femur Twists thigh (and lower leg) outward; maintains posture by stabilizing hip joint Femur Lateral rotation
    Obturator internus Inner surface of obturator membrane; greater sciatic notch; margins of obturator foramen Greater trochanter in front of piriformis Twists thigh (and lower leg) outward; maintains posture by stabilizing hip joint Femur Lateral rotation
    Piriformis Anterolateral surface of sacrum Greater trochanter of femur Twists thigh (and lower leg) outward; maintains posture by stabilizing hip joint Femur Lateral rotation
    Quadratus femoris Ischial tuberosity Trochanteric crest of femur Twists thigh (and lower leg) outward; maintains posture by stabilizing hip joint Femur Lateral rotation
    Superior gemellus Ischial spine Greater trochanter of femur Twists thigh (and lower leg) outward; maintains posture by stabilizing hip joint Femur Lateral rotation
    Adductors
    Adductor brevis Body of pubis; inferior ramus of pubis Linea aspera above adductor longus Brings thighs back together; assists with raising knee Femur Adduction; flexion
    Adductor longus Pubis near pubic symphysis Linea aspera Brings thighs back together; assists with raising knee Femur Adduction; flexion
    Adductor magnus Ischial rami; pubic rami; ischial tuberosity Linea aspera; adductor tubercle of femur Brings thighs back together; assists with raising knee and moving thigh back Femur Adduction; flexion; extension
    Pectineus Pectineal line of pubis Lesser trochanter to linea aspera of posterior aspect of femur Opens thighs; assists with raising the knee and turning the thigh (and lower leg) inward Femur Adduction; flexion; medial rotation

    The tensor fascia latae is a thick, squarish muscle in the superior aspect of the lateral thigh. It acts as a synergist of the gluteus medius and iliopsoas in flexing and abducting the thigh. It also helps stabilize the lateral aspect of the knee by pulling on the iliotibial tract (band), making it taut. Deep to the gluteus maximus, the piriformis, obturator internus, obturator externus, superior gemellus, inferior gemellus, and quadratus femoris laterally rotate the femur at the hip.

    The adductor longus, adductor brevis, and adductor magnus can both medially and laterally rotate the thigh depending on the placement of the foot. The adductor longus flexes the thigh, whereas the adductor magnus extends it. The pectineus adducts and flexes the femur at the hip as well. The pectineus is located in the femoral triangle, which is formed at the junction between the hip and the leg and also includes the femoral nerve, the femoral artery, the femoral vein, and the deep inguinal lymph nodes.

    Thigh Muscles That Move the Femur, Tibia, and Fibula

    Deep fascia in the thigh separates it into medial, anterior, and posterior compartments (Figure \(\PageIndex{1}\) and Table \(\PageIndex{2}\)). The muscles in the medial compartment of the thigh are responsible for adducting the femur at the hip. Along with the adductor longus, adductor brevis, adductor magnus, and pectineus, the strap-like gracilis adducts the thigh in addition to flexing the leg at the knee.

    Table \(\PageIndex{2}\): Thigh Muscles That Move the Femur, Tibia, and Fibula

    Prime Mover Origin Insertion Movement Target Target Motion Direction
    Medial Compartment of Thigh
    Gracilis Inferior ramus; body of pubis; ischial ramus Medial surface of tibia Moves back of lower legs up toward buttocks, as when kneeling; assists in opening thighs Femur; tibia/fibula

    Thigh: adduction

    Lower leg: flexion

    Anterior Compartment of Thigh: Quadricepts Femoris Group
    Rectus femoris Anterior inferior iliac spine; superior margin of acetabulum Patella; tibial tuberosity Moves lower leg out in front of body, as when kicking; assists in raising knee Femur; tibia/fibula

    Thigh: flexion

    Lower leg: extension

    Sartorius Anterior superior iliac spine Medial aspect of proximal tibia Moves back of lower legs up and back toward the buttocks, as when kneeling; assists in moving thigh diagonally upward and outward as when mounting a bike Femur; tibia/fibula

    Thigh: flexion; abduction; lateral rotation

    Lower leg: flexion

    Vastus intermedius Proximal femur shaft Patella; tibial tuberosity Moves lower leg out in front of body, as when kicking Tibia/fibula Extension
    Vastus lateralis Greater trochanter; intertrochanteric line; linea apera Patella; tibial tuberosity Moves lower leg out in front of body, as when kicking Tibia/fibula Extension
    Vastus medialis Linea aspera; intertrochanteric line Patella; tibial tuberosity Moves lower leg out in front of body, as when kicking Tibia/fibula Extension
    Posterior Compartment of Thigh: Hamstring Group
    Biceps femoris Ischial tuberosity; linea aspera; distal femur Head of fibula; lateral condyle of tibia Moves back of lower legs up and back toward the buttocks, as when kneeling; moves thigh down and back; twists the thigh (and lower leg) outward Femur; tibia/fibula

    Thigh: extension; lateral rotation

    Lower leg: flexion

    Semimembranosus Ischial tuberosity Medial condyle of tibia; lateral condyle of femur Moves back of lower legs up and back toward the buttocks, as when kneeling; moves thigh down and back; twists the thigh (and lower leg) outward Femur; tibia/fibula

    Thigh: extension; medial rotation

    Lower leg: flexion

    Semitendinosus Ischial tuberosity Upper tibial shaft Moves back of lower legs up and back toward the buttocks, as when kneeling; moves thigh down and back; twists the thigh (and lower leg) outward Femur; tibia/fibula

    Thigh: extension; medial rotation

    Lower leg: flexion

    The muscles of the anterior compartment of the thigh flex the thigh and extend the leg. This compartment contains the quadriceps femoris group, which actually comprises four muscles that extend and stabilize the knee. The rectus femoris is on the anterior aspect of the thigh, the vastus lateralis is on the lateral aspect of the thigh, the vastus medialis is on the medial aspect of the thigh, and the vastus intermedius is between the vastus lateralis and vastus medialis and deep to the rectus femoris. The tendon common to all four is the quadriceps tendon (patellar tendon), which inserts into the patella and continues below it as the patellar ligament. The patellar ligament attaches to the tibial tuberosity. In addition to the quadriceps femoris, the sartorius is a band-like muscle that extends from the anterior superior iliac spine to the medial side of the proximal tibia. This versatile muscle flexes the leg at the knee and flexes, abducts, and laterally rotates the leg at the hip. This muscle allows us to sit cross-legged.

    The posterior compartment of the thigh includes muscles that flex the leg and extend the thigh. The three long muscles on the back of the knee are the hamstring group, which flexes the knee. These are the biceps femoris, semitendinosus, and semimembranosus. The tendons of these muscles form the popliteal fossa, the diamond-shaped space at the back of the knee.

    Muscles That Move the Feet and Toes

    Similar to the thigh muscles, the muscles of the leg are divided by deep fascia into compartments, although the leg has three: anterior, lateral, and posterior (Figure \(\PageIndex{2}\) and Table \(\PageIndex{3}\)).

    Anterior and posterior views of the superficial muscles of the right lower leg; posterior view of the deep muscles of the right lower leg.
    Figure \(\PageIndex{2}\): Muscles of the Lower Leg. The muscles of the anterior compartment of the lower leg are generally responsible for dorsiflexion, and the muscles of the posterior compartment of the lower leg are generally responsible for plantar flexion. The lateral and medial muscles in both compartments invert, evert, and rotate the foot. (Image credit: "Muscles of the Leg that Move the Foot and Toes" by Openstax is licensed under CC BY 4.0)

    Table \(\PageIndex{3}\): Muscles That Move the Feet and Toes

    Prime Mover Origin Insertion Movement Target Target Motion Direction
    Anterior Compartment of Leg
    Extensor digitorum longus Lateral condyle of tibia; proximal portion of fibula; interosseous membrane Middle and distal phalanges of toes 2 - 5 Raises the sole of the foot off the ground, as when preparing to foot-tap; extends toes Foot; toes 2 - 5

    Foot: dorsiflexion

    Toes: extension

    Extensor hallucis longus Anteromedial fibula shaft; interosseous membrane Distal phalanx hallux (big toe) Raises the sole of the foot off the ground, as when preparing to foot-tap; extends the big toe Foot; big toe

    Foot: dorsiflexion

    Big toe: extension

    Tibialis anterior Lateral condyle and upper tibial shaft; interosseous membrane Interior surface of medial cuneiform; first metatarsal bone Raises the sole of the foot off the ground as when preparing to foot-tap; bends the inside of the foot upwards, as when catching your balance while falling laterally toward the opposite side as the balancing foot Foot Dorsiflexion; inversion
    Lateral Compartment of Leg
    Fibularis (peroneus) brevis Distal fibula shaft Proximal end of fifth metatarsal Lowers the sole of the foot to the ground as when foot-tapping or jumping; bends the inside of the foot downward, as when catching your balance while falling laterally toward the same side as the balancing foot Foot Plantar flexion; eversion
    Fibularis longus Upper portion of lateral fibula First metatarsal; medial cuneiform Lowers the sole of the foot to the ground as when foot-tapping or jumping; bends the inside of the foot downward, as when catching your balance while falling laterally toward the same side as the balancing foot Foot Plantar flexion; eversion
    Posterior Compartment of Leg: Superficial Muscles
    Gastrocnemius Medial and lateral condyles of femur Posterior calcaneus Lowers the sole of the foot to the ground, as when foot-tapping or jumping; assists in moving the back of the lower legs up and back toward the buttocks Foot; tibia/fibula

    Foot: plantar flexion

    Tibia/fibula: flexion

    Plantaris Posterior femur above lateral condyle Calcaneus or calcaneus tendon Lowers the sole of the foot to the ground, as when foot-tapping or jumping; assists in moving the back of the lower legs up and back toward the buttocks Foot; tibia/fibula

    Foot: plantar flexion

    Tibia/fibula: flexion

    Soleus Superior tibia; fibula; interosseous membrane Posterior calcaneus Lowers the sole of the foot to the ground, as when foot-tapping or jumping; maintains posture while walking Foot Plantar flexion
    Tibialis posterior Superior tibia; fibula; interosseous membrane Several tarsals and metatarsals 2 - 4 Lowers the sole of the foot to the ground, as when foot-tapping or jumping Foot Plantar flexion
    Posterior Compartment of Leg: Deep Muscles
    Flexor digitorum longus Posterior tibia Distal phalanges of toes 2 - 5 Lowers the sole of the foot to the ground, as when foot-tapping or jumping; bends the inside of the foot upward and flexes toes Foot; toes 2 - 5

    Foot: plantar flexion; inversion

    Toes: flexion

    Flexor hallucis longus Midshaft of fibula; interosseous membrane Distal phalanx of hallux (big toe) Flexes big toe Foot; big toe

    Foot: plantar flexion

    Big toe: flexion

    Popliteus Lateral condyle of femur; lateral meniscus Proximal tibia Moves the back of the lower legs up and back toward buttocks; assists in rotation of the leg at the knee and thigh Tibia/fibula

    Tibia/fibula: flexion

    Thigh and lower leg: medial and lateral rotation

    The muscles in the anterior compartment of the leg: the tibialis anterior, a long and thick muscle on the lateral surface of the tibia, the extensor hallucis longus, deep under it, and the extensor digitorum longus, lateral to it, all contribute to raising the front of the foot when they contract. The fibularis tertius, a small muscle that originates on the anterior surface of the fibula, is associated with the extensor digitorum longus and sometimes fused to it, but is not present in all people. Thick bands of connective tissue called the superior extensor retinaculum (transverse ligament of the ankle) and the inferior extensor retinaculum, hold the tendons of these muscles in place during dorsiflexion.

    The lateral compartment of the leg includes two muscles: the fibularis longus (peroneus longus) and the fibularis brevis (peroneus brevis). The superficial muscles in the posterior compartment of the leg all insert onto the calcaneal tendon (Achilles tendon), a strong tendon that inserts into the calcaneal bone of the ankle. The muscles in this compartment are large and strong and keep humans upright. The most superficial and visible muscle of the calf is the gastrocnemius. Deep to the gastrocnemius is the wide, flat soleus. The plantaris runs obliquely between the two; some people may have two of these muscles, whereas no plantaris is observed in about seven percent of other cadaver dissections. The plantaris tendon is a desirable substitute for the fascia lata in hernia repair, tendon transplants, and repair of ligaments. There are four deep muscles in the posterior compartment of the leg as well: the popliteus, flexor digitorum longus, flexor hallucis longus, and tibialis posterior.

    The foot also has intrinsic muscles, which originate and insert within it (similar to the intrinsic muscles of the hand). These muscles primarily provide support for the foot and its arch, and contribute to movements of the toes (Figure \(\PageIndex{3}\) and Table \(\PageIndex{4}\)). The principal support for the longitudinal arch of the foot is a deep fascia called plantar aponeurosis, which runs from the calcaneus bone to the toes (inflammation of this tissue is the cause of “plantar fasciitis,” which can affect runners. The intrinsic muscles of the foot consist of two groups. The dorsal group includes only one muscle, the extensor digitorum brevis. The second group is the plantar group, which consists of four layers, starting with the most superficial.

    lateral view of the doral  superficial muscles of the right foot; plantar views of: superficial muscles, intermediate muscles, and deep muscles, of the left sole of foot
    Figure \(\PageIndex{3}\): Intrinsic Muscles of the Foot. The muscles along the dorsal side of the foot (a) generally extend the toes while the muscles of the plantar side of the foot (b, c, d) generally flex the toes. The plantar muscles exist in three layers, providing the foot the strength to counterbalance the weight of the body. In this diagram, these three layers are shown from a plantar view beginning with the bottom-most layer just under the plantar skin of the foot (b) and ending with the top-most layer (d) located just inferior to the foot and toe bones. (Image credit: "Intrinsic Muscles of the Foot" by Openstax is licensed under CC BY 4.0)

    Table \(\PageIndex{4}\): Intrinsic Muscles in the Foot

    Prime Mover Origin Insertion Movement Target Target Motion Direction
    Dorsal Group
    Extensor digitorum brevis Calcaneus; extensor retinaculum Base of proximal phalanx of big toe; extensor expansions on toes 2 - 5 Extends toes 2 - 5 Toes 2 - 5 Extension
    Plantar Group: Layer 1
    Abductor digiti minimi Calcaneal tuberosity Proximal phalanx of toe 5 (pinky toe) Abducts and flexes toe 5 Toe 5 Abduction; flexion
    Abductor hallucis Calcaneal tuberosity; flexor retinaculum Proximal phalanx of hallux (big toe) Abducts and flexes big toe Big toe Abduction; flexion
    Flexor digitorum brevis Calcaneal tuberosity Middle phalanx of toes 2 - 4 Flexes toes 2 - 4 Middle toes Flexion
    Plantar Group: Layer 2
    Lumbricals tendons of flexor digitorum longus Medial side of proximal phalanx of toes 2 - 5 Extends toes 2 - 5 at the interphalangeal joints; flexes the small toes at the metatarsophalangeal joints Toes 2 - 5 Extension; flexion
    Quadratus plantae Medial and lateral sides of calcaneus Tendon of flexor digitorum longus Assists in flexing toes 2 - 5 Toes 2 - 5 Flexion
    Plantar Group: Layer 3
    Adductor hallucis Bases of metatarsals 2 - 4; fibularis longus tendon sheath; ligament across metatarsophalangeal joints Base of proximal phalanx of hallux (big toe) Adducts and flexes big toe Big toe Adduction; flexion
    Flexor digiti minimi brevis Base of metatarsal 5; tendon sheath of fibularis longus Base of proximal phalanx of toe 5 (pinky toe) Flexes pinky toe Pinky toe Flexion
    Flexor hallicus brevis Lateral cuneiform; cuboid bones Base of proximal phalanx of hallux (big toe) Flexes big toe Big toe Flexion
    Plantar Group: Layer 4
    Dorsal interossei Sides of metatarsals Both sides of toe 2; for each other toe, extensor expansion over first phalanx on side opposite toe 2 Abducts and flexes middle toes at metatarsophalangeal joints; extends middle toes at interphalangeal joints Middle toes Abduction; flexion; extension
    Plantar interossei Side of each metatarsal that faces metatarsal 2 (absent from metatarsal 2) Extensor expansion on first phalanx of each tow ( except on 2) on side facing toe 2 Abducts toes 3 - 5; flexes proximal phalanges and extends distal phalanges Small toes Abduction; flexion; extension

    Concept Review

    The pelvic girdle attaches the legs to the axial skeleton. The hip joint is where the pelvic girdle and the leg come together. The hip is joined to the pelvic girdle by many muscles. In the gluteal region, the psoas major and iliacus form the iliopsoas. The large and strong gluteus maximus, gluteus medius, and gluteus minimus extend and abduct the femur. Along with the gluteus maximus, the tensor fascia lata muscle forms the iliotibial tract. The lateral rotators of the femur at the hip are the piriformis, obturator internus, obturator externus, superior gemellus, inferior gemellus, and quadratus femoris. On the medial part of the thigh, the adductor longus, adductor brevis, and adductor magnus adduct the thigh and medially rotate it. The pectineus muscle adducts and flexes the femur at the hip.

    The thigh muscles that move the femur, tibia, and fibula are divided into medial, anterior, and posterior compartments. The medial compartment includes the adductors, pectineus, and the gracilis. The anterior compartment comprises the quadriceps femoris, quadriceps tendon, patellar ligament, and the sartorius. The quadriceps femoris is made of four muscles: the rectus femoris, the vastus lateralis, the vastus medius, and the vastus intermedius, which together extend the knee. The posterior compartment of the thigh includes the hamstrings: the biceps femoris, semitendinosus, and the semimembranosus, which all flex the knee.

    The muscles of the leg that move the foot and toes are divided into anterior, lateral, superficial- and deep-posterior compartments. The anterior compartment includes the tibialis anterior, the extensor hallucis longus, the extensor digitorum longus, and the fibularis (peroneus) tertius. The lateral compartment houses the fibularis (peroneus) longus and the fibularis (peroneus) brevis. The superficial posterior compartment has the gastrocnemius, soleus, and plantaris; and the deep posterior compartment has the popliteus, tibialis posterior, flexor digitorum longus, and flexor hallucis longus.

    Review Questions

    Q. The large muscle group that attaches the leg to the pelvic girdle and produces extension of the hip joint is the ________ group.

    A. gluteal

    B. obturator

    C. adductor

    D. abductor

    Answer

    Answer: A

    Q. Which muscle produces movement that allows you to cross your legs?

    A. the gluteus maximus

    B. the piriformis

    C. the gracilis

    D. the sartorius

    Answer

    Answer: D

    Q. What is the largest muscle in the lower leg?

    A. soleus

    B. gastrocnemius

    C. tibialis anterior

    D. tibialis posterior

    Answer

    Answer: B

    Q. The vastus intermedius muscle is deep to which of the following muscles?

    A. biceps femoris

    B. rectus femoris

    C. vastus medialis

    D. vastus lateralis

    Answer

    Answer: B

    Critical Thinking Questions

    Q. Which muscles form the hamstrings? How do they function together?

    Answer

    A. The biceps femoris, semimembranosus, and semitendinosus form the hamstrings. The hamstrings flex the leg at the knee joint.

    Q. Which muscles form the quadriceps? How do they function together?

    Answer

    A. The rectus femoris, vastus medialis, vastus lateralis, and vastus intermedius form the quadriceps. The quadriceps muscles extend the leg at the knee joint.

    Glossary

    adductor brevis
    muscle that adducts and medially rotates the thigh
    adductor longus
    muscle that adducts, medially rotates, and flexes the thigh
    adductor magnus
    muscle with an anterior fascicle that adducts, medially rotates and flexes the thigh, and a posterior fascicle that assists in thigh extension
    anterior compartment of the leg
    region that includes muscles that dorsiflex the foot
    anterior compartment of the thigh
    region that includes muscles that flex the thigh and extend the leg
    biceps femoris
    hamstring muscle
    calcaneal tendon
    (also, Achilles tendon) strong tendon that inserts into the calcaneal bone of the ankle
    dorsal group
    region that includes the extensor digitorum brevis
    extensor digitorum brevis
    muscle that extends the toes
    extensor digitorum longus
    muscle that is lateral to the tibialis anterior
    extensor hallucis longus
    muscle that is partly deep to the tibialis anterior and extensor digitorum longus
    femoral triangle
    region formed at the junction between the hip and the leg and includes the pectineus, femoral nerve, femoral artery, femoral vein, and deep inguinal lymph nodes
    fibularis brevis
    (also, peroneus brevis) muscle that plantar flexes the foot at the ankle and everts it at the intertarsal joints
    fibularis longus
    (also, peroneus longus) muscle that plantar flexes the foot at the ankle and everts it at the intertarsal joints
    fibularis tertius
    small muscle that is associated with the extensor digitorum longus
    flexor digitorum longus
    muscle that flexes the four small toes
    flexor hallucis longus
    muscle that flexes the big toe
    gastrocnemius
    most superficial muscle of the calf
    gluteal group
    muscle group that extends, flexes, rotates, adducts, and abducts the femur
    gluteus maximus
    largest of the gluteus muscles that extends the femur
    gluteus medius
    muscle deep to the gluteus maximus that abducts the femur at the hip
    gluteus minimus
    smallest of the gluteal muscles and deep to the gluteus medius
    gracilis
    muscle that adducts the thigh and flexes the leg at the knee
    hamstring group
    three long muscles on the back of the leg
    iliacus
    muscle that, along with the psoas major, makes up the iliopsoas
    iliopsoas group
    muscle group consisting of iliacus and psoas major muscles, that flexes the thigh at the hip, rotates it laterally, and flexes the trunk of the body onto the hip
    iliotibial tract
    muscle that inserts onto the tibia; made up of the gluteus maximus and connective tissues of the tensor fasciae latae
    inferior extensor retinaculum
    cruciate ligament of the ankle
    inferior gemellus
    muscle deep to the gluteus maximus on the lateral surface of the thigh that laterally rotates the femur at the hip
    lateral compartment of the leg
    region that includes the fibularis (peroneus) longus and the fibularis (peroneus) brevis and their associated blood vessels and nerves
    medial compartment of the thigh
    a region that includes the adductor longus, adductor brevis, adductor magnus, pectineus, gracilis, and their associated blood vessels and nerves
    obturator externus
    muscle deep to the gluteus maximus on the lateral surface of the thigh that laterally rotates the femur at the hip
    obturator internus
    muscle deep to the gluteus maximus on the lateral surface of the thigh that laterally rotates the femur at the hip
    patellar ligament
    extension of the quadriceps tendon below the patella
    pectineus
    muscle that abducts and flexes the femur at the hip
    pelvic girdle
    hips, a foundation for the lower limb
    piriformis
    muscle deep to the gluteus maximus on the lateral surface of the thigh that laterally rotates the femur at the hip
    plantar aponeurosis
    muscle that supports the longitudinal arch of the foot
    plantar group
    four-layered group of intrinsic foot muscles
    plantaris
    muscle that runs obliquely between the gastrocnemius and the soleus
    popliteal fossa
    diamond-shaped space at the back of the knee
    popliteus
    muscle that flexes the leg at the knee and creates the floor of the popliteal fossa
    posterior compartment of the leg
    region that includes the superficial gastrocnemius, soleus, and plantaris, and the deep popliteus, flexor digitorum longus, flexor hallucis longus, and tibialis posterior
    posterior compartment of the thigh
    region that includes muscles that flex the leg and extend the thigh
    psoas major
    muscle that, along with the iliacus, makes up the iliopsoas
    quadratus femoris
    muscle deep to the gluteus maximus on the lateral surface of the thigh that laterally rotates the femur at the hip
    quadriceps femoris group
    four muscles, that extend and stabilize the knee
    quadriceps tendon
    (also, patellar tendon) tendon common to all four quadriceps muscles, inserts into the patella
    rectus femoris
    quadricep muscle on the anterior aspect of the thigh
    sartorius
    band-like muscle that flexes, abducts, and laterally rotates the leg at the hip
    semimembranosus
    hamstring muscle
    semitendinosus
    hamstring muscle
    soleus
    wide, flat muscle deep to the gastrocnemius
    superior extensor retinaculum
    transverse ligament of the ankle
    superior gemellus
    muscle deep to the gluteus maximus on the lateral surface of the thigh that laterally rotates the femur at the hip
    tensor fascia lata
    muscle that flexes and abducts the thigh
    tibialis anterior
    muscle located on the lateral surface of the tibia
    tibialis posterior
    muscle that plantar flexes and inverts the foot
    vastus intermedius
    quadricep muscle that is between the vastus lateralis and vastus medialis and is deep to the rectus femoris
    vastus lateralis
    quadricep muscle on the lateral aspect of the thigh
    vastus medialis
    quadricep muscle on the medial aspect of the thigh

    Contributors and Attributions