Lab 21

Muscles of the Pelvis, Leg and Foot

Muscles to know

• psoas major• iliacus• gluteus maximus• gluteus medius• sartorius• quadriceps femoris (4)• gracilus• adductor longus• biceps femoris• semitendinosis• semimembranosus

• tibialis anterior• ext hallucis longus• ext digitorum longus• fibularis (peroneus)

longus• gastrocnemius• soleus• flexor hallucis longus• flexor digitorum longus

Muscles of the Pelvis and Lower Limbs

• Pelvic girdle is tightly bound to axial skeleton:– permits little movement– has few muscles

Muscles that Position the Lower Limbs

1. Muscles that move the thigh

2. Muscles that move the leg

3. Muscles that move the foot and toes

Generally…

• Muscles that are lateral are abductors

• Muscles that are medial are adductors

• flexors are on inner surface of joint

• extensors are on outer surface of joint

Note: in legs and feet, look at each joint individually (cf. arms)

Muscles that Move the Thigh

• Gluteal muscles

• Lateral rotators

• Adductors

• Iliopsoas group

Muscles of hip and thigh

• psoas major

• iliacus

• gluteus maximus

• gluteus medius

• adductor longus

Gluteal Muscles (1 of 2)

• Cover lateral surfaces of ilia

• Gluteus maximus:– largest, most posterior gluteal muscle– produces extension and lateral rotation at

hip– Originates on illiac crest, etc., inserts on

illiotibial tract and femur

Gluteal Muscles (2 of 2)

• Gluteus medius and [gluteus minimus]: – originate anterior to gluteus maximus– insert on trochanter of femur

Muscles that Move the Thigh

Figure 11–19a, b

Muscles that Move the Thigh

Figure 11–19c, d

Adductors

• Adductor longus:– hip flexion and adduction

• Gracilis (UPPER LEG):– hip flexion and adduction

Iliopsoas group

• 2 hip flexors insert on the same tendon: – psoas major

• originates on lumbar vetebrae, inserts on femur

– iliacus• originates on illium/fossa

Summary: Muscles that Move the Thigh

Table 11–16 (1 of 2)

Summary: Muscles that Move the Thigh

Table 11–16 (2 of 2)

Muscles that Move the Leg

• Flexors of the knee:– originate on the pelvic girdle– generally: hamstrings

• Extensors of the knee:– originate on the femoral surface– insert on the patella– generally: quads

Flexors of the Knee

• Biceps femoris

• Semimembranosus

• Semitendinosus

• Sartorius:– originates superior to the acetabulum– long, ribbon-like muscle– traverses the quads and wraps around to the

back of the knee

Hamstrings

• Made up of:– biceps femoris (long and short heads)– semimembranosus– semitendinosus

• All are knee flexors

Muscles that Move the Leg

Figure 11–20a

Extensors of the Knee

• 4 muscles of the quadriceps femoris: – 3 vastus muscles:

• vastus lateralis • vastus medialis• vastus intermedius

– rectus femoris muscle

Muscles that Move the Leg

Figure 11–20b, c

Summary: Muscles that Move the Leg

Table 11–17 (1 of 2)

Summary: Muscles that Move the Leg

Table 11–17 (2 of 2)

Muscles that Move the Foot and Toes

• Extrinsic muscles that move the foot and toes include:– muscles that produce extension at the ankle

(Plantar flexion)– muscles that produce flexion at the ankle– muscles that produce extension at the toes– muscles that produce flexion at the toes

Muscles that Produce Extension at the Ankle (Plantar flexion)

Calf muscles

Large posterior calf muscles, both insert on Achilles):

• Gastrocnemius

• Soleus

• Fibularis longus

Muscles that Move the Foot and Toes

Figure 11–21a, b

Muscles that Move the Foot and Toes

Figure 11–21c, d

The Achilles Tendon

• The calcaneal tendon (Achilles tendon):– shared by the gastrocnemius and soleus

Muscles that Produce Flexion at the Ankle

• Tibialis anterior:– opposes the gastrocnemius

Muscles that Move the Foot and Toes

Figure 11–21a, b

Muscles that Move the Foot and Toes

Figure 11–21c, d

Muscles that Produce Extension at the Toes

• Extensor digitorum longus

• Extensor hallucis longus

Toe extensors are on top of foot

Note: there are no muscles in toes themselves (only tendons)

The Intrinsic Muscles of the Foot

Figure 11–22a

Muscles that Produce Flexion at the Toes

• Flexor digitorum longus

• Flexor hallucis longus:– oppose the extensors

Toe flexors are on bottom of foot

The Intrinsic Muscles of the Foot

Figure 11–22b, c

Summary: Muscles that Move the Foot and Toes

Table 11–18

Today

• Lab 21– Ignore muscles that are not on the list

Due Next Week