Ch 9 Muscles Part 4

Question 1

Muscles Crossing Hip and Knee Joints

Answer 1

Most anterior muscles flex femur at hip, extend leg at knee (foreswing of walking)

Most posterior muscles extend thigh, flex leg (backswing of walking)

Medial muscles all adduct thigh
All three groups enclosed by fascia lata

Question 2

Movements of the Thigh

Answer 2

Include flexion, extension, abduction, adduction, circumduction, and rotation

Thigh flexors pass in front of hip joint

Iliopsoas (iliacus and psoas major) - prime mover of flexion
Tensor fasciae latae
Rectus femoris
Assisted by medial adductors and sartorius

Thigh extensors

Hamstring muscles - prime movers of extension
Biceps femoris
Semitendinosus
Semimembranosus
Gluteus maximus – assists hamstrings in forceful thigh extension

Question 3

Movement of thigh- adductor

Answer 3

Abductors
Gluteus maximus (also laterally rotates thigh)
Gluteus medius (also medially rotates thigh)
Gluteus minimus (also medially rotates thigh)
Piriformis (also laterally rotates thigh)
Obturator externus (also laterally rotates thigh)
Obturator internus (also laterally rotates thigh)
Gemellus (also laterally rotates thigh)

Question 4

Muscles of the Thigh that Move the Knee Joint

Answer 4

Quadriceps femoris—sole extensor of knee

Hamstring muscles—flex knee; antagonists to quadriceps femoris

Question 5

Fascia of the Leg

Answer 5

Deep fascia of leg continuous with fascia lata

Segregates leg into three compartments - anterior, lateral, and posterior

Fascia thickens distally; forms flexor, extensor, and fibular retinaculae

Question 6

Muscles of the Leg: Movements

Answer 6

Various leg muscles produce following movements

Ankle—dorsiflexion and plantar flexion
Intertarsal joints—inversion and eversion of the foot
Toes—flexion and extension

Question 7

Muscles of the Anterior Compartment of 
the Leg

Answer 7

Primary toe extensors and ankle dorsiflexors

Tibialis anterior
Extensor digitorum longus
Extensor hallucis longus
Fibularis tertius (not always present)

Question 8

Muscles of the Lateral Compartment of
the Leg

Answer 8

Plantar flexion and eversion of the foot; stabilize lateral ankle and lateral longitudinal arch of foot

Fibularis longus
Fibularis brevis

Question 9

Muscles of the Posterior Compartment of the Leg

Answer 9

Plantar flex ankle
Gastrocnemius
Soleus
Plantaris
Popliteus
Flexor digitorum longus
Flexor hallucis longus
Tibialis posterior

Question 10

Intrinsic Muscles of the Foot

Answer 10

Help flex, extend, abduct, and adduct toes
Support arches of foot; some leg tendons assist
Extensor digitorum brevis—dorsal foot muscle; helps extend toes

Question 11

Plantar Muscles

Answer 11

Four layers of plantar muscles

Superficial layer-
Flexor digitorum brevis
Abductor hallucis
Abductor digiti minimi

Second layer-
Flexor accessorius
Lumbricals

Third layer
Flexor hallucis brevis
Adductor hallucis
Flexor digiti minimi brevis
 Deepest layer
Plantar and dorsal interossei