Week 5 - Musculoskeletal

Question 1

The sciatic nerve exits the pelvis through the greater sciatic foramen, and typically passes immediately inferior to which muscle?

• a) Superior Gemellus
• b) Inferior Gemellus
• c) Piriformis
• d) Obturator Externus
• e) Quadratus Femoris

Answer 1

The scietic nerve exits the pelvis through the greater sciatic foramen inferior to the piriformis muscle along with the pudendal nerve and vessels, inferior gluteal nerve and vessels, nerve to obturator internus, and posterior cutaneous nerve.

When the sciatic nerve reaches the apex of the popliteal fossa, it terminates by bifurcating into the tibial and common fibular nerves.

Question 2

Label the major landmarks on the plain radiograph below:

Answer 2

Question 3

The main dorsiflexor at the ankle joint is the ……………, which receives its motor supply from the …………………. nerve.

Answer 3

The main dorsiflexor at the ankle joint is the tibialis anterior which receives its motor supply from the deep fibular/peroneal nerve.

Tibialis Anterior: The tibialis anterior muscle is located alongside the lateral surface of the tibia and is the strongest dorsiflexor of the foot.

Question 4

Rupture of the Achilles (calcaneal) tendon causes a loss of which movement at the ankle joint?

Answer 4

= Plantar flexion

The Achilles (calcaneal) tendon is a common tendon shared between the gastrocnemius and soleus muscles of the posterior leg and attaches them to the calcaneus.

There’s one muscle on the front of the leg for dorsiflexion, tibialis anterior. There are three on the back of the leg for plantar flexion, gastrocnemius, soleus, and plantaris.

Dorsum of foot (top) & plantar (sole)

Question 5

Label the cadaver image below:

Answer 5

Remember the fibula is lateral to the tibia

Question 6

Which of the following muscles is the prime abductor at the hip joint?

• a) Gluteus Maximus
• b) Gluteus Medius
• c) Obturator Internus
• d) Quadratus Femoris
• e) Iliopsoas

Answer 6

Prime Hip ABductor = Gluteus Medius

The gluteal region is an anatomical area located posteriorly to the pelvic girdle, at the proximal end of the femur. The muscles in this region move the lower limb at the hip joint.

The muscles of the gluteal region can be broadly divided into two groups:

• Superficial abductors and extenders – group of large muscles that abduct and extend the femur. Includes the gluteus maximus, gluteus medius, gluteus minimus and tensor fascia lata.
• Deep lateral rotators – group of smaller muscles that mainly act to laterally rotate the femur. Includes the quadratus femoris, piriformis, gemellus superior, gemellus inferior and obturator internus.