Muscles of the legs

Superficial Muscles of the Body – Anterior View Figure 11.7a

Superficial Muscles of the Body – Posterior View Figure 11.7b

Muscle Compartments of the Thigh Posterior compartment muscles Extend the hip and flex the knee Innervation is the tibial branch of the sciatic nerve Anterior compartment muscles Flex the hip and extend the knee Innervation is the femoral nerve Medial compartment Adduct the thigh Innervation is the obturator nerve

Compartments of the Leg Posterior compartment muscles Contains digital and plantar flexors Innervation is the tibial nerve Anterior compartment muscles Contains digital extensors and dorsiflexors Innervation is the deep fibular nerve Lateral compartment muscles Plantar flex and evert the foot Innervation is the superficial fibular nerve

Muscle Compartments of the Thigh and Leg Figure 11.6a

Muscle Compartments of the Thigh and Leg Figure 11.6b

Muscles Crossing the Hip and Knee Joints Thigh and leg movements Anterior muscles Flex the thigh and extend the leg at the knee Posterior muscles Extend the thigh and flex the leg

Muscles Crossing the Hip and Knee Joints Thigh and leg movements Adductor muscles – on medial aspect of thigh Adduct the thigh only Deep fascia of the thigh Surrounds and encloses all three groups

Muscles Crossing the Hip and Knee Joints Movements at the hip joint Muscles that flex the thigh Originate on vertebral column or pelvis Muscles that extend the thigh Arise posterior to the hip joint Adductors originate medial to the hip joint Abductors originate lateral to the hip joint

Muscles Crossing the Hip and Knee Joints: Movements of the Thigh and Leg Anterior and Medial Muscles (Pelvis or Backbone origin) ATTACHMENT MUSCLE ACTION (prime movers) Muscle Origin Insertion Action Nerve Supply Iliacus Iliac fossa, sacral ala Lesser trochanter of femur (via iliopsoas tendon) Thigh and trunk flexion Femoral n. Psoas major Transverse processes (fleshy strips), bodies; disc of Lumbar vert. & T12 Thigh and trunk flexion; and flexion of vertebral column Ventral rami (L1 – L3) Sartorius Ant. Sup. Iliac spine Medial knee & proximal tibia Flex abducts and laterally rotates thigh; flexes knee Iliopsoas

Anterior and Medial Muscles Origin on pelvis or vertebral column Iliacus Psoas major Sartorius Muscles of the medial compartment Adductor longus Adductor brevis Adductor magnus Pectineus Gracilis

Anterior and Medial Muscles Figure 11.20a

Muscles of the Anterior Compartment of the Thigh Quadriceps femoris Has four separate heads Has a common insertion at the quadriceps tendon Powerful knee extensors Rectus femoris Vastus lateralis Vastus medialis Vastus intermedius Tensor fasciae latae

Muscles Crossing the Hip and Knee Joints: Movements of the Thigh and Leg (Medial Thigh Muscles) ATTACHMENT MUSCLE ACTION (prime movers) Muscles Origin Insertion F Nerve Supply Adductor longus Pubis (near symphysis pubis) Linea aspera Adducts, flexes, and medially rotates thigh Obturator n. (L2 – L4) Adductor brevis Body & inf. Pubic rami Linea aspera (above adductor longus) Adducts and medially rotates thigh Obturator n. Adductor magnus Ischial and pubic rami & ischial tuberosity Linea aspera; medial supracondylar line, adductor tubercle of femur Anterior part- adducts and medially rotates and nflexes. Posterior part- synergist with hamstring muscles in thigh extension Obturator n. and Sciatic n. (L2 – L4) Pectineus Pectineal line of pubis and sup. ramus From lesser trochanter to linea aspera Femoral n. (sometimes Obturator n.) Gracilis Inf. Ramus & body of the pubis (and adjacent ischial ramus) Medial tibial surface (inf. To medial condyle) Adducts thigh, flexes, & medially rotates leg Adductors

Muscles of the Anterior Compartment of the Thigh Figure 11.20a

Muscles Crossing the Hip and Knee Joints: Movements of the Thigh and Leg (Anterior Thigh Muscles) ATTACHMENT MUSCLE ACTION (prime movers) Muscles Origin Insertion F Nerve Supply Rectus femoris Ant. Inf. Iliac spine; & Sup. Margin of acetabulum Patellar ligament (Patella and tibial tuberosity Extends knee & flexes thigh at hip Femoral n. (L2 – L4) Vastus lateralis Greater trochanter, intertrochanteric line, linea aspera Patellar ligament (Patella and tibial tuberosity) Extends and stabilizes thigh Vastus medialis Linea aspera, medial supracondylar line, intertrochanteric line Extends knee Vastus intermedius Anterior and lateral surface of femur Tensor fasciae latae Anterior iliac crest & ant. sup. Iliax spine Iliotibial tract (ensheaths all muscle of the thigh) Steadies trunk on thigh (makes the iliotibial tract taut) Superior gluteal n. (L4 – L5) Quadriceps femoris

Posterior Muscles Origin on pelvis or sacrum Gluteus maximus Gluteus medius Gluteus minimus Lateral rotators Piriformis Obturator externus Obturator internus Superior and inferior gemellus Quadratus femoris PLAY Movement at the hip joint: an overview

Posterior Muscles Figure 11.21b

Muscles Crossing the Hip and Knee Joints: Movements of the Thigh and Leg (Posterior Muscles, Gluteal muscles) POSTERIOR MUSCLES ATTACHMENT (Origin on Pelvis or Sacrum) MUSCLE ACTION (prime movers) Gluteal Muscles Origin Insertion Action Nerve Supply Gluteus maximus Dorsal Ilium, sacrum, and coccyx Gluteal tuberosity (femur); Iliotibial tract Major extensor of thigh Inferior gluteal n. (L5, S1, S2) Gluteus medius Between ant. And post. Gluteal lines (lateral ilium) Lateral aspect of greater trochanter (femur) Abducts and medially rotates thigh Superior gluteal n. (L5, S1) Gluteus minimus Between ant. & inf. Gluteal lines on external surface of ilium Ant. Border of greater trochanter of femur As for gluteus medius

Muscles Crossing the Hip and Knee Joints: Movements of the Thigh and Leg (Posterior Muscles, Lateral Rotators) POSTERIOR MUSCLES ATTACHMENT (Origin on Pelvis or Sacrum) MUSCLE ACTION (prime movers) Lateral Rotator Muscles Origin Insertion Action Nerve Supply Piriformis Anterolateral surface of sacrum Sup. Border greater trochanter (femur) Rotates extended thigh laterally S1 and S2, L5 Obturator externus Outer surface of obturator membrane; External surface of pubis and ischium and margins of obturator foramen By a tendon into trochanteric fossa of posterior femur As for piriformis Obturator n. Obturator internus Inner surface of obturator membrane; greater sciatic notch; margins of obturator foramen Greater trochanter (in front of piriformis) L5 and S1 Gemellus Superior- Ischial spine Inferior- Ischial tuberosity Greater trochanter (femur) Quadratus femoris Iscial tuberosity Intertrochanteric crest (femur) Rotates thigh laterally and stabilizes hip joint

Muscles of the Posterior Compartment of the Thigh Hamstrings Biceps femoris Semitendinosus Semimembranosus Figure 11.21a

Muscles Crossing the Hip and Knee Joints: Movements of the Thigh and Leg (Posterior Thigh Muscles) ATTACHMENT MUSCLE ACTION (prime movers) Muscles Origin Insertion Action Nerve Supply Biceps femoris Long head- ischial tuberosity Short head- Linea aspera, lateral supracondylar ridge, & distal femur Common tendon at lateral border of popliteal fossa to insert into head of fibula and lateral condyle of tibia Extends thigh and flexes knee Sciatic n. (Tibial n. to long head; Common fibular n. to short head) Semitendinosus Ischial tuberosity (common w/ long head of biceps femoris) Medial aspect of upper tibial shaft Extends thigh at hip; flexes knee Sciatic n. – tibial n. portion (L5 – S2) Semimembranosus Ischial tuberosity Medial condyle of tibia Hamstrings

Muscles of the Leg Fascia lata of the leg surrounds muscles Tightly binds muscles Prevents swelling during exercise Aids venous return Divides leg into three compartments Tendons are held in place by Extensor, fibular, and flexor retinacula Muscle movement at ankle and intertarsal joints

Muscles of the Anterior Compartment Tibialis anterior Extensor digitorum longus Fibularis (peroneus) tertius Extensor hallucis longus PLAY Muscles of the ankle and foot (b) Figure 11.22a

Muscles of the Leg: Movements of the Ankle and Toes LEG MUSCLES ATTACHMENT MUSCLE ACTION (prime movers) Anterior Compartment Muscles Origin Insertion Action Nerve Supply Tibialis anterior Lateral condyle & upper 2/3 of tibial shaft; interosseous membrane By tendon into inferior surface of medial cuneiform and metatarsal 1 Prime mover of dorsiflexion Deep fibular n. (L4 & L5) Extensor digitorum longus Lateral condyle of tibia; proximal ¾ of fibula; interosseous membrane Middle & distal phalanges 2-5 (via extensor expansion) Prime mover of toe extension Deep fibular n. (L5 & S1) Fibularis (peroneus) tertius Distal anterior surface of fibula and interosseous membrane Tendon inserts on dorsum of metatarsal 5 Dorsiflexes and everts foot Extensor hallucis longus Anteromedial fibula shaft and interosseous membrane Tendon inserts on distal phalanx of great toe) Extends great toe

Muscles of the Lateral Compartment Fibularis (peroneus) longus Fibularis (peroneus) brevis Flexor hallucis longus Extensor hallucis longus Fibularis tertius PLAY Muscles of the ankle and foot (c) Figure 11.23a

Muscles of the Lateral Compartment Figure 11.23b, c

Muscles of the Leg: Movements of the Ankle and Toes (Lateral Compartment) LEG MUSCLES ATTACHMENT MUSCLE ACTION (prime movers) Lateral Compartment Muscles Origin Insertion Action Nerve Supply Fibularis (peroneus) longus Fibular head; upper & lateral fibula By long tendon (curves under the foot) to Metatarsal 1 & medial cuneiform Plantar flexion & everts foot Superficial fibular n. (L5 – S2) Fibularis (peroneus) brevis Distal fibular shaft By tendon (behind lateral malleolus) to proximal end of Metatarsal 5 Superficial fibular n.

Muscles of the Posterior Compartment Superficial muscles Triceps surae Gastrocnemius Soleus Plantaris PLAY Muscles that act on the ankle and foot: an overview

Muscles of the Posterior Compartment Figure 11.24a, b

Muscles of the Leg: Movements of the Ankle and Toes (Posterior Compartment, Superficial) LEG MUSCLES ATTACHMENT MUSCLE ACTION (prime movers) Posterior Compartment (Superficial) Muscles Origin Insertion Action Nerve Supply Gastrocnemius (medial and lateral head) 2 heads from medial & lateral femoral condyle Posterior calcaneus (via calcaneal tendon) Plantar flexes foot Tibial n. (S1 and S2) Soleus (Cone shaped) Superior tibia, fibula, & interosseous membrane As for gastrocnemius Tibial n. Plantaris Posterior femur (above lateral condyle) (Via a long thin tendon) into calcaneus (or calcaneal tendon) Assist in knee flexion and plantar flexion of foot Triceps Surae

Muscles of the Posterior Compartment Deep muscles Popliteus Flexor digitorum longus Flexor hallucis longus Tibialis posterior PLAY Muscles of the ankle and foot (a) PLAY Muscles of the ankle and foot (d) Figure 11.24c

Muscles of the Leg: Movements of the Ankle and Toes (Posterior Compartment, Deep) LEG MUSCLES ATTACHMENT MUSCLE ACTION (prime movers) Posterior Compartment (Deep) Muscles Origin Insertion Action Nerve Supply Popliteus Lateral condyle (femur); Lateral meniscus (knee) Proximal tibia Flexes and rotates leg medially to unlock knee from full extension when flexion begins Tibial n. (L4 – S1) Flexor digitorum longus (Extensive) Posterior tibia (Tendon behind medial malleolus) into distal phalanges 2 - 5 Plantar flexes and inverts foot; flexes toes (“grips ground”) Tibial n. (L5 – S2) Flexor hallucis longus Middle fibular shaft; interosseous membrane (Tendon runs under foot) to distal phalanx of great toe Plantar flexes and inverts foot; flexes great toe at all joints (“push off muscle during walking”) Tibialis posterior Superior tibia and fibula; interosseous membrane (Tendon passes behind medial malleolus & under arch of foot) into several tarsals and metatarsals 2 - 4 Prime mover of foot inversion Tibial n. (L4 & L5)