Muscles Of Posterior Thigh

Question 1

Which three muscles are collectively called the hamstrings?

Answer 1

Biceps femoris
Semitendinosus (lateral)
Semimembranosus (medial)

Question 2

Biceps femoris

• Origin and insertion?
• Innervation?
• Actions?

Answer 2

Biceps femoris has two heads, a long head and a short head.

Long head
- Origin: ischial tuberosity
- Insertion: head of fibula with short head
Innervation: tibial part of sciatic nerve

Short head

• Origin: linea aspera of posterior femur
• Insertion: head of fibula with long head
• Innervation: common fibular part of sciatic nerve

Actions: both heads - knee flexion, hip extension, lateral rotation of knee & hip

Question 3

Semitendinosus

• Origin and insertion?
• Innervation?
• Actions?

Answer 3

• Origin: ischial tuberosity
• Insertion: medial tibia
• Innervation: tibial part of sciatic nerve
• Actions: knee flexion, hip extension, medial rotation of hip & knee

Question 4

Semimembranosus

• Origin and insertion?
• Innervation?
• Actions?

Answer 4

• Origin: superior part of ischial tuberosity
• Insertion: medial tibial condyle
• Innervation: tibial part of sciatic nerve
• Actions: knee flexion, hip extension, medial rotation of knee & hip