1. The Muscular System Part E08
The Muscular System
Part E

2. Muscles Crossing Hip and Knee Joints
Most anterior compartment muscles of the hip and thigh flex the femur at the hip and extend the leg at the knee
Posterior compartment muscles of the hip and thigh extend the thigh and flex the leg
The medial compartment muscles all adduct the thigh
These three groups are enclosed by the fascia lata

3. Movements of the Thigh at the Hip: Flexion and Extension
The ball-and-socket hip joint permits flexion, extension, abduction, adduction, circumduction, and rotation
The most important thigh flexors are the iliopsoas (prime mover), tensor fasciae latae, and rectus femoris
The medially located adductor muscles and sartorius assist in thigh flexion

4. Movements of the Thigh at the Hip: Flexion and Extension
Thigh extension is primarily effected by the hamstring muscles (biceps femoris, semitendinosus, and semimembranosus)
Forceful extension is aided by the gluteus maximus

5. Muscles of the lower limb
Name: Iliosoas
Origin:
Ilium & Lumbar vertebrae
Insertion:
Femur
Primary action:
Flexes hip

6. Name: Tensor fascia latae
Origin: Iliac crest
Insertion: Iliotibial tract
Primary actions: Thigh - flexion, medial rotation, abduction.

7. Name: Rectus femoris
Origin: anterior inferior iliac spine
Insertion: inserts into the patellar tendon as one of the four quadriceps muscles
Primary actions: hip flexion; knee extension

8. Muscles of the lower limb
Name: Sartorius
Origin:
Ilium
Insertion:
Proximal tibia
Primary action:
Flexes thigh on hip

9. Muscles of the lower limb
Name: Hamstring Group (biceps femoris, semimembranosus, & semitendinosus)
Origin:
Ischial tuberosity
Insertion:
Proximal tibia
Primary action:
Flex knee and extend hip

10. Muscles of the lower limb
Name: Gluteus maximus
Origin:
Sacrum & ilium
Insertion:
Proximal femur
Primary action:
Extends hip

11. Movements of the Thigh at the Hip: Flexion and Extension
Figure 10.19a

12. Movements of the Thigh at the Hip: Other Movements
Abduction and rotation are effected by the gluteus medius and gluteus minimus, and are antagonized by the lateral rotators
Thigh adduction is the role of five adductor muscles (adductor magnus, adductor longus, and adductor brevis; the pectineus, and the gracilis)

13. Muscles of the lower limb
Name: Gluteus medius
Origin:
ilium
Insertion:
Proximal femur
Primary action:
Abducts thigh; steadies pelvis during walking

14. Name: Gluteus minimus (located directly beneath the gluteus medius)
Origin: Gluteal surface of ilium, under gluteus medius.
Insertion: Greater trochanter of the femur
Primary actions: abduction and medial rotation of hip

15. Muscles of the lower limb
Name: Adductor muscles (adductor magnus, adductor longus, and adductor brevis; the pectineus, and the gracilis)
Origin:
Pelvis
Insertion:
Proximal femur
Primary action:
Adduct thigh

16. Movements of the Thigh at the Hip: Other Movements
Figure 10.20a

17. Movements of the Thigh at the Hip: Other Movements
Figure 10.20b

18. Movements of the Knee Joint
The primary extensor of the knee is the quadriceps femoris
The hamstring muscles flex the knee, and are antagonists to the quadriceps femoris
Figure 10.19a

19. Muscles of the lower limb
Name: Quadriceps Group (rectus femoris & 3 vastus muscles)
Origin:
Vasti; femur
Rectus; pelvis
Insertion:
Tibial tuberosity via patellar tendon
Primary action:
Extend knee & flex hip

20. Muscles of the lower limb
Name: Hamstring Group (biceps femoris, semimembranosus, & semitendinosus)
Origin:
Ischial tuberosity
Insertion:
Proximal tibia
Primary action:
Flex knee and extend hip

21. 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
Figure 10.22a

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

23. Muscles of the Anterior Compartment
These muscles are the primary toe extensors and ankle dorsiflexors
They include the tibialis anterior, extensor digitorum longus, extensor hallucis longus, and fibularis tertius
Figure 10.21a

24. Muscles of the lower limb
Name: Tibialis Anterior
Origin:
Proximal tibia
Insertion:
1st tarsal and metatarsal
Primary action:
Dorsiflexes and inverts the foot

25. Muscles of the lower limb
Name: Extensor Digitorum Longus
Origin:
Proximal tibia
Insertion:
Distal toes 2-5
Primary action:
Extends toes and dorsi-flexes foot

26. Name: extensor hallucis longus
Origin: middle portion of fibula
Insertion: dorsal side of the base of the distal phalanx of the big toe
Primary actions: Extends the big toe and assists in dorsiflexion of the foot

27. Name: fibularis (aka peroneus) tertius
Origin: distal anterior surface of the fibula
Insertion: dorsal surface of metatarsal 5
Primary actions: dorsiflexion and eversion of the foot

28. Muscles of the Anterior Compartment
Figure 10.21b-d

29. Muscles of the Lateral Compartment
These muscles plantar flex and evert the foot
They include the fibularis longus and fibularis brevis muscles
Figure 10.22a

30. Muscles of the lower limb
Name: Fibularis Muscles (longus, brevis)
Origin:
Fibula
Insertion:
1st Metatarsal (longus)
5th Metatarsal (brevis)
Primary action:
Plantar flexion and evert foot

31. Muscles of the Lateral Compartment
Figure 10.22b, c

32. Muscles of the Posterior Compartment
These muscles primarily flex the foot and the toes
They include the gastrocnemius, soleus, tibialis posterior, flexor digitorum longus, and flexor hallucis longus
Figure 10.23a

33. Muscles of the lower limb
Name: Gastrocnemius
Origin:
Distal femur
Insertion:
calcaneus
Primary action:
Plantar flexes the foot and flexes the knee

34. Muscles of the lower limb
Name: Soleus
Origin:
Proximal tibia and fibula
Insertion:
calcaneus
Primary action:
Plantar flexes the foot

35. Name: tibialis posterior
Origin: tibia, fibula
Insertion: navicular, medial cuneiform
Primary actions: inversion of the foot, plantar flexion of the foot

36. Name: flexor digitorium longus
Origin: posterior tibia
Insertion: Plantar surface; base of the distal phalanges of the four lesser toes
Primary actions: Primary action is Flex digits

37. Name: flexor hallucis longus
Origin: fibula
Insertion: Plantar surface; base of distal phalanx
Primary actions: flexes all joints of the big toe, plantar flexion of the ankle joint

38. Muscles of the Posterior Compartment
Figure 10.23b, c

39. Muscles of the Posterior Compartment
Figure 10.23d-f

40. Muscle Actions of the Thigh: Summary
Thigh muscles:
Flex and extend the thigh (posterior compartment)
Extend the leg (anterior compartment)
Adduct the thigh (medial compartment)

41. Muscle Actions of the Thigh: Summary
Figure 10.24a

42. Muscle Actions of the Leg: Summary
Leg muscles:
Plantar flex and evert the foot (lateral compartment)
Plantar flex the foot and flex the toes (posterior compartment)
Dorsiflex the foot and extend the toes (anterior compartment)

43. Muscle Actions of the Leg: Summary
Figure 10.24b

44. Intrinsic Muscles of the Foot
These muscles help flex, extend, abduct, and adduct the toes
In addition, along with some leg tendons, they support the arch of the foot
There is a single dorsal foot muscle, the extensor digitorum brevis, which extends the toes
The plantar muscles occur in four layers

45. Plantar Muscles: First Layer (Superficial)
Superficial muscles of the plantar aspect of the foot
These muscles are similar to the corresponding muscles of the hand
Figure 10.25a

46. Plantar Muscles: Second Layer
Figure 10.25b

47. Plantar Muscles: Third Layer
Figure 10.25d

48. Plantar Muscles: Fourth Layer
Figure 10.25e-f