1. The Muscular System: Part D10
The Muscular System: Part D

2. Muscles Crossing Hip and Knee Joints
Most anterior muscles flex the femur at the hip and extend the leg at the knee (foreswing of walking)
Most posterior muscles extend the thigh and flex the leg (backswing of walking)
Medial muscles all adduct the thigh
All three groups are enclosed by the fascia lata

3. Thigh flexors pass in front of the hip joint
Movements of the Thigh
Include flexion, extension, abduction, adduction, circumduction, and rotation
Thigh flexors pass in front of the hip joint
Iliopsoas (iliacus and psoas major): prime mover of flexion
Tensor fasciae latae
Rectus femoris
Assisted by medial adductors and sartorius

4. Anterior superior iliac spine Tensor fasciae latae Pectineus
12th rib
12th thoracic vertebra
Quadratus lumborum
Psoas minor
Iliac crest
Psoas major
Iliopsoas
Iliacus
5th lumbar vertebra
Anterior superior iliac spine
Tensor fasciae latae
Pectineus
Adductor longus
Sartorius
Gracilis
Quadriceps femoris
Adductor magnus
• Rectus femoris
• Vastus lateralis
• Vastus medialis
Tendon of quadriceps femoris
Patella
Patellar ligament
(a)
Figure 10.19a

5. Hamstring muscles (prime movers of extension)
Movements of the Thigh
Thigh extensors
Hamstring muscles (prime movers of extension)
Biceps femoris
Semitendinosus
Semimembranosus
Gluteus maximus (prime mover during forceful extension)

6. Gluteus medius Gluteus maximus Adductor magnus Gracilis
Iliotibial tract
Long head
Biceps
femoris
Short head
Hamstrings
Semitendinosus
Semimembranosus
(a)
Figure 10.20a

7. Adductors (also medially rotate thigh)
Movements of the Thigh
Adductors (also medially rotate thigh)
Adductor magnus
Adductor longus
Adductor brevis
Pectineus
Gracilis

8. Pectineus (cut) Adductor brevis Adductor magnus Adductor longus Femur
O = origin
I = insertion
(b)
Figure 10.19b

9. Movements of the Thigh 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)

10. Gluteus medius (cut) Gluteus minimus Superior gemellus Piriformis
Obturator
internus
Obturator
externus
Inferior
gemellus
Quadratus
femoris
Gluteus
maximus
(cut)
(c)
Figure 10.20c

11. Muscles of the Thigh that Move the Knee Joint
Quadriceps femoris—sole extensor of the knee
Hamstring muscles—flex the knee, and are antagonists to the quadriceps femoris

12. Anterior superior iliac spine Tensor fasciae latae Pectineus
12th rib
12th thoracic vertebra
Quadratus lumborum
Psoas minor
Iliac crest
Psoas major
Iliopsoas
Iliacus
5th lumbar vertebra
Anterior superior iliac spine
Tensor fasciae latae
Pectineus
Adductor longus
Sartorius
Gracilis
Quadriceps femoris
Adductor magnus
• Rectus femoris
• Vastus lateralis
• Vastus medialis
Tendon of quadriceps femoris
Patella
Patellar ligament
(a)
Figure 10.19a

13. Gluteus medius Gluteus maximus Adductor magnus Gracilis
Iliotibial tract
Long head
Biceps
femoris
Short head
Hamstrings
Semitendinosus
Semimembranosus
(a)
Figure 10.20a

14. Fascia of the Leg
A deep fascia of the leg is continuous with the fascia lata
This fascia segregates the leg into three compartments: anterior, lateral, and posterior
Distally, the fascia thickens and forms the flexor, extensor, and fibular retinaculae

15. Muscles of the Leg: Movements
Various leg muscles produce the following movements
Ankle—dorsiflexion and plantar flexion
Intertarsal joints—inversion and eversion of the foot
Toes—flexion and extension

16. Muscles of the Anterior Compartment of the Leg
Primary toe extensors and ankle dorsiflexors
Tibialis anterior
Extensor digitorum longus
Extensor hallucis longus
Fibularis tertius (not always present)

17. Extensor digitorum longus
Fibularis longus
Gastrocnemius
Tibia
Tibialis anterior
Extensor digitorum longus
Soleus
Extensor hallucis longus
Fibularis tertius
Superior and inferior
extensor retinacula
Extensor hallucis brevis
Extensor digitorum brevis
(a)
Figure 10.21a

18. Muscles of the Lateral Compartment of the Leg
Plantar flexion and eversion of the foot
Fibularis longus
Fibularis brevis

19. Extensor digitorum longus
Patella
Head of fibula
Gastrocnemius
Soleus
Fibularis longus
Extensor digitorum longus
Tibialis anterior
Extensor hallucis longus
Fibularis tertius
Fibularis brevis
Superior and inferior extensor
retinacula
Flexor hallucis longus
Extensor hallucis brevis
Fibular retinaculum
Extensor digitorum brevis
Lateral malleolus
(a)
5th metatarsal
Figure 10.22a

20. Muscles of the Posterior Compartment of the Leg
Flexors of the foot and the toes
Gastrocnemius
Soleus
Plantaris
Popliteus
Tibialis posterior
Flexor digitorum longus
Flexor hallucis longus

21. (a) Superficial view of the posterior leg.
Plantaris
Medial head
Gastrocnemius
Lateral head
Tendon of
gastrocnemius
Calcaneal tendon
Medial malleolus
Lateral malleolus
Calcaneus
(a) Superficial view of the posterior leg.
Figure 10.23a

22. Flexor hallucis longus
Plantaris (cut)
Gastrocnemius
lateral head (cut)
Gastrocnemius
medial head (cut)
Popliteus
Soleus (cut)
Tibialis posterior
Fibula
Fibularis longus
Flexor digitorum
longus
Flexor hallucis longus
Tendon of tibialis
posterior
Fibularis brevis
Medial malleolus
Calcaneal tendon (cut)
Calcaneus
(c) The triceps surae has been removed to show the
deep muscles of the posterior compartment.
Figure 10.23c

23. Major Actions of Muscles Acting on the Thigh, Leg, and Foot
View the next five slides for a summary of the major actions of the muscles acting on the thigh, leg, and foot

24. Posterior compartment of thigh (flexes leg and extends
Adductors
Hamstrings
Vastus
lateralis
Femur
Posterior compartment of
thigh (flexes leg and extends
thigh); innervation: tibial
nerve (portion of sciatic nerve)
Vastus
intermedius
Rectus femoris
(a)
Vastus medialis
Posterior
compartment
muscles
Anterior
compartment
muscle
Medial
compartment
muscles of thigh
and lateral
muscles of leg
Medial compartment (adducts
thigh); innervation: obturator
nerve
Anterior compartment (extends leg);
innervated by femoral nerve
(a) Muscles of the thigh
Figure 10.25a

25. Posterior compartment of leg (plantar flexes foot,
muscles
Triceps surae
Anterior
compartment
muscle
Fibula
Medial
compartment
muscles of thigh
and lateral
muscles of leg
Fibularis
muscles
Posterior compartment
of leg (plantar flexes foot,
flexes toes); innervated
by tibial nerve
(b)
Tibialis
anterior
Tibia
Lateral compartment of leg
(plantar flexes and everts foot);
innervation: superficial
fibular nerve
Anterior compartment of leg
(dorsiflexes foot, extends toes);
innervated by deep fibular nerve
(b) Muscles of the leg
Figure 10.25b

26. Table Part 1

27. Table Part 2

28. Intrinsic Muscles of the Foot
Help flex, extend, abduct, and adduct the toes
Support the arches of the foot along with some leg tendons
Extensor digitorum brevis—dorsal foot muscle that helps extend the toes

29. Extensor digitorum longus
Fibularis longus
Gastrocnemius
Tibia
Tibialis anterior
Extensor digitorum longus
Soleus
Extensor hallucis longus
Fibularis tertius
Superior and inferior
extensor retinacula
Extensor hallucis brevis
Extensor digitorum brevis
(a)
Figure 10.21a

30. Plantar Muscles The plantar muscles occur in four layers
Superficial layer
Flexor digitorum brevis
Abductor hallucis
Abductor digiti minimi
Second layer
Flexor accessorius
Lumbricals

31. Tendon of flexor hallucis longus
Lumbricals
Flexor hallucis brevis
Flexor digiti minimi brevis
Abductor hallucis
Flexor digitorum brevis
Flexor accessorius
Abductor digiti minimi
Calcaneal tuberosity
(a) First layer (plantar aspect)
Figure 10.24a

32. Flexor hallucis brevis
Lumbricals
Flexor hallucis brevis
Flexor hallucis longus tendon
Flexor digitorum longus (tendon)
Flexor digiti minimi brevis
Abductor digiti minimi
Flexor accessorius
Fibularis longus (tendon)
Flexor digitorum longus (tendon)
Flexor hallucis longus (tendon)
(b) Second layer (plantar aspect)
Figure 10.24b

33. Plantar Muscles 3. Third layer 4. Deepest layer Flexor hallucis brevis
Adductor hallucis
Flexor digiti minimi brevis
4. Deepest layer
Plantar and dorsal interossei

34. Adductor hallucis (transverse head)
Adductor hallucis (oblique head)
Interosseous muscles
Flexor hallucis brevis
Flexor digiti minimi brevis
Fibularis longus (tendon)
Flexor accessorius
Flexor digitorum longus (tendon)
Flexor hallucis longus (tendon)
(c) Third layer (plantar aspect)
Figure 10.24c

35. (d) Fourth layer (plantar aspect): plantar interossei
Figure 10.24d