MSK, Week 3 (14.4 Popliteal Fossa)

Question 1

Biceps Femoris

Answer 1

Origin:
Long head- ischial tuberosity
Short head- linea aspera and lateral supracondylar line of femur

Insertion:
Lateral side of head of fibula; tendon is split at this site by 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 leg and rotates it laterally when knee is flexed; extends thigh (e.g. accelerating mass during first step of gait)

Question 2

Gracillis

Answer 2

Origin:
Body and inferior ramus of pubis

Insertion:
Superior part of medial surface of tibia

Innervation:
Obturator nerve (L2, L3)

Action:
Adducts thigh; flexes leg; helps rotate leg medially

Question 3

Sartorius

Answer 3

Origin:
ASIS and 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 leg at knee joint (medially rotating leg when knee is flexed)

Question 4

Semitendinosus

Answer 4

Origin:
Ischial tuberosity

Insertion:
Medial surface of superior part of tibia

Innervation:
Tibial division of sciatic nerve

Action:
Extend thigh; flex leg and rotate it medially when knee is flexed; when thigh and leg are flexed, these muscles can extend trunk

Question 5

Gastrocnemius

Answer 5

Origin:
Lateral head- lateral aspect of lateral condyle of femur
Medial head- popliteal surface of femur; superior to medial condyle

Insertion:
Posterior surface of calcaneus via calcaneal tendon

Innervation:
Tibial nerve (S1, S2)

Action: Plantar flexes ankle when knee is extended; raises heal during walking; flexes leg at knee joint

Question 6

Plantaris

Answer 6

Origin:
Inferior end of lateral supracondylar line of femur; oblique popliteal ligament

Insertion:
Posterior surface of calcaneus via calcaneal tendon

Innervation:
Tibial nerve (S1, S2)

Action: Weakly assists gastrocnemius in plantar flexing ankle

Question 7

Soleus

Answer 7

Origin:
Posterior aspect of head and superior quarter of posterior surface of fibula; soleal line and middle third of medial border of tibia; and tendinous arch extending between the bony attachments

Insertion:
Posterior surface of calcaneous via calcaneal tendon

Innervation:
Tibial nerve

Action:
Plantar flexes ankle independent of position of knee; steadies leg on foot

Question 8

Popliteus

Answer 8

Origin:
Lateral surfaces of lateral condyle of femur and lateral meniscus

Insertion:
Posterior surface of tibia; superior to soleal line

Innervation:
Tibial nerve

Action:
Weakly flexes knee and unlocks it by rotating femur five degrees on fixed tibia; medially rotates tibia of unplanted limb

Question 9

Adductor Magnus

Answer 9

Origin:
Adductor part- inferior ramus of pubis , ramus of ischium
Hamstings part: ischial tuberosity

Insertion:
Adductor part: gluteal tuberosity, line aspera, medial supraondular line
Hamstring part: adductor tubercle of femor

Innervation:
Adductor part: Obturator nerve
Hamstring part: Tibial Part of sciatic nerve

Action:
Adducts thigh