Lecture 16: Muscles of the Appendicular Skeleton II

I. Muscles that Stabilize and Move Thigh at the Hip

A. General characteristics

1. Movements

a. Flexion

b. Extension

c. Abduction

d. Adduction

e. Rotation (internal and external)

B. Anterior muscles

1. Primarily flexors

2. Iliopsaos

a. Major flexor of thigh

b. Compound muscle

i. Iliacus

ii. Psoas

c. Different origins

i. Iliacus: iliac fossa

ii. Psoas: transvers process of 12^th thoracic thru 5^th lumbar vertebrae

d. Common insertion: lesser trochanter of femur

C. Posterior hip muscles

1. Primarily extensors, abductors and rotators

2. Three gluteal muscles

a. G. maximus

i. Origin: dorsal ilium

ii. Insertion: gluteal tuberosity of femur

iii. Action: chief extensor of thigh; raises body from sitting position; straightens leg during walking

b. G. medius

i. Origin: lateral ilium

ii. Insertion: greater trochanter of femur

iii. Action: major abductor of the thigh

c. G. minimus

i. Origin: external surface of ilium

ii. Insertion: greater trochanter of femur

iii. Action: major abductor of the thigh

3. Tensor fascia latae

a. Origin: outer ant. iliac creast

b. Insertion: lateral condyle of tibia via iliotibia tract

c. Action: abductor

4. Six external rotators

a. Piriformis

b. Obturator externus

c. Obturator internus

d. Gemellus

i. Superior

ii. Inferior

e. Quadratus femoris

f. Origins: posterior portion of pelvis

g. Insertions: greater trochanter of femur

h. Actions: rotate thigh laterally and stabilize hip joint

II. Muscle of thigh moving leg at hip and knee joints

A. Medial compartment

1. Adductors

a. Adductor magnus

i. Origin: ischial and pubic rami

ii. Insertion: linea aspera and adductor tubercle of femor

iii. Action: adducts and laterally rotates

b. Adductor longus

i. Origin: pubis

ii. Insertion: linea aspera of femor

iii. Action: adducts and laterally rotates

c. Adductor brevis

i. Origin: pubic ramus

ii. Insertion: linea aspera of femor (above longus)

iii. Action: adducts and laterally rotates

2. Pectineus

a. Origin: pubis

b. Insertion: posterior aspect of femur

c. Action: adducts, flexes and rotates thigh

3. Gracilis

a. Origin: inf. ramus of pubis

b. Insertion: medial surface of tibia

c. Action: adducts thigh, flexes and rotates leg

B. Medial compartment

1. Quadriceps femoris (compound muscle)

a. Rectus femoris

b. Vastus lateralis

c. Vastus medialis

d. Vastus intermedius

e. Insertions: patella and tibial tuberosity via patellar ligament

f. Origins:

i. Vastus muscles: proximal anterior femur shaft

ii. Rectus femoris: anterior inf. iliac spine

g. Actions: chief extensor at knee

i. Rectus femoris: assistant flexor at hip

2. Sartorius

a. Origin: ant. superior iliac spine

b. Insertion: medial aspect of proximal tibia

c. Action: flexes and laterally rotates thigh

3. Posterior compartment: three hamstring muscles

a. Biceps femoris

i. Origins: ishial tuberosity (long head), distal femur (short head)

ii. Insertion: common tendon inserting into head of fibula and lateral condyle of tibia

iii. Action: extends thigh, flexes knee, laterally rotates leg

b. Semitendinosus

i. Origin: ishial tuberosity

ii. Insertion: medial aspect of upper tibial shaft

iii. Action: extends thigh, flexes knee, medially rotates leg

c. Semimembranous

i. Origin: ishial tuberosity

ii. Insertion: medial condyle of tibia

iii. Action: extends thigh, flexes knee, medially rotates leg

III. Muscles of the Leg

A. General characteristics

1. Primary movements

a. Dorsal and plantar flexion

b. Inversion and eversion

B. Anterior compartment

a. Tibialis anterior

i. Origin: lateral condyle of tibia and upper tibial shaft

ii. Insertion: medial cuneiform and 1^st metatarsal

iii. Action: prime mover of dorsiflexion

b. Extensor digitorum

i. Origin: lateral condyle of tibia and proximal ¾ of fibula

ii. Insertion: 2^nd and 3^rd phalanges

iii. Action: dorsiflexion of foot; prime mover of toe extention

c. Peroneus (fibularis) tertius

i. Origin: distal anterior surface of fibula

ii. Insertion: lateral malleolus and 5^th metatarsal

iii. Action: dorsiflexes and everts foot

d. Extensor hallucis

i. Origin: anteromedial fibula shaft

ii. Insertion: distal phalanx of great toe

iii. Action: extends great toe; dorsiflexes foot

C. Lateral compartment

a. Peroneus longus

i. Origin: upper portion of fibula

ii. Insertion: medial cunneiform and 1^st metatarsal

iii. Action: plantar flexes and everts foot

b. Peroneus brevis

i. Origin: distal portion of anterior fibula shaft

ii. Insertion: 5^th metatarsal

iii. Action: plantar flexes and everts foot

D. Posterior compartment: calf muscles

1. General characteristics

a. Chief plantar flexors of foot and toes

2. Superficial muscles: triceps surae and plantaris

a. Gastrocnemius

i. Origin: medial and lateral condyles of femur

ii. Insertion: calcaneus

iii. Action: plantar flexes foot

b. Soleus

i. Origin: superior tibia and fibula

ii. Insertion: calcaneus

iii. Action: plantar flexes ankle

c. Plantaris

i. Origin: posterior femur

ii. Insertion: calcaneus

iii. Action: plantar flexes foot and assists in knee flexion

3. Deep muscles

a. Flexor digitorum longus

i. Origin: tibial shaft

ii. Insertion: distal phalanx of 2^nd thru 5^th toes

iii. Action: plantar flexes and inverts foot

b. Flexor hallucis longus

i. Origin: fibular shaft

ii. Insertion: distal phalanx of great toe

iii. Action: plantar flexes and inverts foot

c. Tibialis posterior

i. Origin: upper portion of fibula and tibia

ii. Insertion: several tarsals and metatarsals

iii. Action: prime mover of foot inversion; plantar flexes ankle

d. Popliteus

i. Origin: lateral condyle of femur

ii. Insertion: proximal tibia

iii. Action: flexes and rotates leg medially

IV. Foot

(Not covered)