Muscles of the Lower Appendage

(Thigh, Leg, & Foot)

Nestor T. Hilvano, M.D., M.P.H.

Learning Objectives

You should be able to: 1. Identify the principal muscles of the

pelvis and lower limbs and indicate their origin, insertion, action, and innervation.

2. Compare the major functional differences between these muscles.

3. Solve common anatomic and physiologic problems based on what you have learned on this topic.

Muscles that move/acting on the Thigh

• Iliopsoas muscle– crosses anterior surface of hip joint and

inserts on femur– iliacus portion arises from iliac fossa– psoas portion arises from lumbar vertebrae– major hip flexor

Muscles that move the Thigh

• Gluteus maximus– forms mass of the buttock– Action: prime hip extensor and lateral rotation at hip– provides most of lift when you climb stairs

• Iliotibial band– band of fascia lata and inserts on the tibia– Action: laterally brace the knee

___ Which of the following is important when balancing on one foot?

a. iliopsoas b. gluteus maximus c. sartorius d. iliotibial tract

Deep Gluteal Muscles

• Most laterally rotate the hip

- pyriformis, superior and gemellus (superior and inferior), obturator internus, quadratus femoris

• Except: Gluteus medius and Gluteus minimus medially rotates

Muscles Acting on the Knee• Hamstring Muscle - consists of:

1. Biceps femoris2. SemitendinosusSemimembranosus

- Action: flexors of knee and hip extension - Injured in running and kicking ball sports.

• Sartorius - from ASIS to medial surface of tibia - Action: flexion of knee and lateral rotation of hip (crossing your legs)

____ What is the longest muscle of the body?

a. Hamstring muscle b. Sartorius muscle c. quadriceps femoris

Muscles Acting on the Knee• Anterior thigh muscles-extends knee joint• Quadriceps femoris tendon insert to tibial tuberosity via patellar

ligament; consists of:

1.vastus lateralis

2. rectus femoris

3. vastus intermedius

4. vastus medialis• rectus femoris also flexes hip joint• Anterior compartment syndrome (shin splint injury) is commonly

caused by ___.

a. jogging b. running

c. strain groins d. soccer game

Anterior Compartment of Leg

• Tibialis anterior = flexion (dorsiflexion) at ankle and inverts foot

• Extensor hallucis longus = extension of big toe• Extensor digitorum longus = extension of toes 2- 5

Posterior Compartment of Leg

Superficial group of plantar flexors: •Gastrocnemius = extension (plantar flexion) at ankle• Soleus = extension (plantar flexion) at ankle• Calcaneal tendon = attaches these muscles to heel boneDeep group of plantar flexors: •Flexor digitorum longus (2nd-5th toes), Tibialis posterior, and Flexor hallucis longus (big toe) are plantar flexors.•Popliteus unlocks the knee joint for knee flexion.

Lateral Compartment of the Leg

• Fibularis longus and brevis

• Both plantar flex and evert the foot

• Provides lift and forward thrust

Intrinsic Muscles of Sole

• Four muscle layers • Support for arches• Abduct and adduct, flex the toes• One dorsal muscle – extensor digitorum brevis

extends toes

Homework (Self Review) 1. Compare the hamstring muscles and quadriceps femoris muscles

as to components and primary actions.

2. Give the actions of the muscles below:

___ pyriformis & obturator internus a. adduction of the hip

___ gracilis b. lateral rotation of the hip

___ gluteus medius c. maintain longitudinal arch

___ intrinsic muscles of sole d. medial rotation of the hip

3. Name the muscle that corresponds to the following actions:

___ crossing your legs a. gluteus maximus

___ dorsiflexion of ankle b. iliopsoas

___ plantar flexion of ankle c. extensor digitorum brevis

___ major hip extensor d. tibialis anterior

___ extend toes e. sartorius

___ major hip flexor f. calf muscles