Knee Muscles

Question 1

Rectus Femoris

Answer 1

O: Anterior inferior iliac spine and ilium superior to acetabulum
I: Via common tendinous and independent attachments to base of patella
Innervation: Femoral L2-L4
A: Extends knee joint: rectus femoris also steadies hip joint and helps iliopsoas flex hip joint

Question 2

Vastus lateralis

Answer 2

Origin- Greater trochanter/ lateral lip of linea aspera of femur
Insertion- Common tendinous and independent attachments to base of patella ; medial and lateral vasti also attach to tibia and patella via aponeuroses
Innervation- Femoral nerve L3, L4
Action- extends knee joint; rectus femoris steadies hip joint and iliopsoas flexes hip joint

Question 3

Vastus Medialis

Answer 3

Origin- Intertrochanteric line and medial lip of linea aspera of femur
Insertion- via common tendinous and independent attachments to base of the patella; medial and lateral vasti also attach to tibia and patella via aponeurosis
Innervation- Femoral nerve L2-L4
Action- Extends knee joint; rectus femoris also steadies hip joint and helps iliopsoas flex hip joint

Question 4

Vastus Intermedius

Answer 4

A
Origin- Anterior and lateral surfaces of shaft of femur
Insertion- Via common tendinous and independent attachments to base of patella; medial and lateral vasti also attach to tibia and patella via aponeurosis
Innervation- Femoral nerve L2-L4
Action- Extends knee joint; rectus femoris also steadies hip joint and helps iliopsoas flex hip joint

Question 5

Articularis Genu

Answer 5

Origin: A derivative of the vastus intermedius
Insert: inserts superiorly onto the inferior aspect of the femur and inferiorly on the synovial membrane of the knee joint
Action: pulls the synovial membrane superiorly during extension of the leg there by preventing folds of the membrane from being compressed between the femur and the patella within the knee joint
Innervation: femoral L2-L4

Question 6

Sartorius

Answer 6

Origin- Iliac spine/Superior part of notch inferior to it
Insertion- Superior part of medial surface of tibia
Innervation- Femoral nerve L2, L3
Action - flexes, abducts and laterally rotates hip; flexes knee

Question 7

Gracilis

Answer 7

Origin- Body of inferior ramus of pubis
Insertion- Superior part of medial surface of tibia
Innervation- Obturator nerve L2, L3
Action Adducts hip joint; flexes knee joint, medially rotating when flexed

Question 8

Semitendinosus

Answer 8

Origin- Ischial tuberosity
Insertion- Superior part of media surface of tibia
Innervation- Tibial division of sciatic nerve part of tibia L5, S1, S2
Action- Extend hip joint; flex knee joint and medially rotate it when flexed

Question 9

Semimembranosus

Answer 9

Origin- Ischial tuberosity
Insertion- posterior part of medial condyle of tibia
Innervation- Tibial division of sciatic nerve part of tibia L5, S1,S2
Action- extend hip joint; flex knee joint and medially rotate it when flexed

Question 10

Biceps femoris

Answer 10

Origin-
Long head; Ischial tuberosity
Short head; linea aspera and lateral supracondylar line of femur
Insertion- Lateral side of head of fibula, tendon split at site of fibular collateral ligament of knee
Innervation-
Long head; tibial division of sciatic nerve L5, S1, S2
Short head; common fibular division of sciatic nerve L5, S1, S2
Action- flexes knee and laterally rotates it when flexed; long head extends hip joint

Question 11

Tibialis Anterior

Answer 11

O: Lateral condyle and superior half of lateral surfaces of tibia and interosseous membrane
I: Medial and inferior surfaces of medial cuneiform and base of 1st metatarsal
I: Deep Fibular nerve
A: Dorsiflexes ankle joint and inverts subtalar joint

Question 12

Extensor Hallucis Longus

Answer 12

O: Middle part of anterior surface of fibula and interosseous membrane
I: Dorsal aspect of base of distal phalanx of great toe
I: Deep fibular nerve
A: Extends great toe and dorsiflexes ankle joint

Question 13

Extensor Digitorum Longus

Answer 13

O: Lateral condyle of tibia and superior three quarters of medial surface of fibula and interosseous membrane
I: Middle and distal phalanges of lateral four digits
I: deep Fibular Nerve
A: Extends lateral 4 digits and dorsiflexes ankle joint

Question 14

Fibularis Tertius

Answer 14

O: Inferior third of anterior surface of fibula and interosseous membrane
I: Dorsum of base of 5th metatarsal
I: Deep Fibular Nerve
A: Dorsiflexes ankle joint and aids in eversion if subtalar joint

Question 15

Fibularis Longus

Answer 15

O: Head and superior two thirds of lateral surface of fibula
I: Base of 1st metatarsal and medial cuneiform
I: superficial Fibular Nerve
A: Everts subtalar joint and weakly plantarflexes ankle joint

Question 16

Fibularis Brevis

Answer 16

O: Inferior two thirds of lateral surface of fibula
I: Dorsal surface of tuberosity on lateral side of base of 5th metatarsal
I: Superficial Fibular Nerve
A: Everts subtalar joint and weakly plantarflexes ankle joint

Question 17

Gastrocnemius Lateral head

Answer 17

O: lateral head: Lateral aspect of lateral condyle of femur
I: posterior surface of calcaneus via calcaneal tendon
I: Tibial Nerve
A: Plantarflexes ankle joint when knee joint is extended: raises heel during walking: flexes knee joint

Question 18

Gastrocnemius Medial Head

Answer 18

O: Popliteal surface if femur: superior to medial condyle
I: Posterior surface of calcaneus via calcaneal tendon
I: Tibial nerve
A: Plantarflexes ankle joint when knee joint is extended: raises heel during walking: flexes knee joint

Question 19

Soleus

Answer 19

O: Posterior aspect of head and superior quarter of posterior surface of fibula: Soleal line and middle third of medial border of tibia: tendinous arch extending between the bony attachments
I: Posterior surface of calcaneus via calcaneal tendon
I: tibial Nerve
A: Plantarflexes ankle joint independent of position of knee : stabilizes ankle joint

Question 20

Plantaris

Answer 20

O: Inferior end of lateral supracondylar line of femur: oblique popliteal ligament
I: Posterior surface of calcaneus via calcaneal tendon
I: tibial nerve
A: weakly assists gastrocnemius in plantarflexing ankle joint

Question 21

Popliteus

Answer 21

O: Lateral surface of lateral condyle of femur and lateral meniscus
I: posterior surface of tibia and superior to soleal line
I: Tibial Nerve
A: Weakly flexes knee joint and unlocks it by rotating femur 5 degrees on fixed tibia: medially rotates tibia of unplanted limb

Question 22

Flexor Hallucis Longus

Answer 22

O: Inferior two thirds of posterior surface of fibula: inferior part of interosseous membrane
I: Base of distal phalanx of great toe
I: Tibial nerve
A: Flexes great toe at all joints: weakly plantarflexes ankle joint: supports medial longitudinal arch of foot

Question 23

Flexor Digitorum Longus

Answer 23

O: Medial part of posterior surface of tibia inferior to soleal line: by a broad tendon to fibula
I: bases of distal Phalanges of lateral four digits
I: tibial nerve
A: Flexes lateral four digits: plantarflexes ankle joint: supports longitudinal arches of the foot

Question 24

Tibialis Posterior

Answer 24

O: Interosseous membrane : posterior surface of tibia inferior to soleal line: posterior surface of fibula
I: Tuberosity of navicular cuneiform, cuboid and sustentaculum tali of calcaneus: bases of 2nd, 3rd and 4th metatarsals
I: Tibial Nerve
A: Plantarflexes ankle joint: inverts foot: Maintains medial longitudinal arch