MSK - Posterior Thigh Muscles

Question 1

What are the three muscles that form the hamstrings?

Answer 1

• Biceps Femoris
• Semitendinosus (most superficial)
• Semimebranosus

Question 2

What is the origin of biceps femoris?

Answer 2

• Long head = Ischial Tuberosity

- Short head = Linea aspera of the femur

Question 3

Where does biceps femoris insert?

Answer 3

Heads converge to form a tendon that attaches at the head of the fibula

Question 4

What is the arterial supply of biceps femoris?

Answer 4

Deep femoral artery and perforating arteries

Question 5

What are the actions of biceps femoris?

Answer 5

• Flexion of the leg at the knee
• Lateral rotation of the knee when flexed
• Long head = extension of the leg at the hip

Question 6

What is the origin of semitendinosus?

Answer 6

Ischial tuberosity

Question 7

Where does semitendinosus insert?

Answer 7

Posteriomedial surface of the tibia

Question 8

What is the innervation of semitendinosus?

Answer 8

Tibial part of the sciatic nerve (L5-S2)

Question 9

What is the arterial supply of semitendinosus?

Answer 9

Inferior gluteal artery and perforating arteries

Question 10

What are the actions of semitendinosus?

Answer 10

• Flexion of the leg at the knee
• Extension of the leg at the hip
• Some medial rotation

Question 11

What is the innervation of biceps femoris?

Answer 11

• Long head = tibial part of the sciatic nerve (L5-S2)

- Short head = fibular part of the sciatic nerve (L5-S2)

Question 12

What is the origin of semimembranosus?

Answer 12

Ischial tuberosity (but is superior to other muscles)

Question 13

Where does semimembranosus insert?

Answer 13

Medial tibial condyle

Question 14

What is the innervation of semimembranosus?

Answer 14

Tibial part of the sciatic nerve (L5-S2)

Question 15

What is the arterial supply of semimembranosus?

Answer 15

• Profunda femoris

- Gluteal arteries

Question 16

What are the actions of semimembranosus?

Answer 16

• Flexion of the leg at the knee
• Extension of the thigh at the hip
• Medial rotation of the leg at both the knee and hip joints

Question 17

Describe a hamstring strain. When are these most likely to occur?

Answer 17

• Excessive stretching/tearing of the muscle fibres

- Seen in athletes involved in running/kicking sports

Question 18

What can happen as a result of a hamstring strain?

Answer 18

Muscle damage can rupture the surrounding blood vessels which causes a haematoma that is contained in the fascia lata to form

Question 19

What is an avulsion fracture? What happens with an avulsion fracture of the ischial tuberosity?

Answer 19

• The breaking away of a small part of a bone from its main body
• Hamstrings tear off a piece of the ischial tuberosity usually during an activity that requires rapid contraction/relaxation of the muscles e.g. football