PHT 1124: EK Ch10-Knee Muscle Review

Which of the following muscles is a primary knee extensor?

• Biceps femoris

• Semitendinosus

• Vastus lateralis

• Sartorius

Answer explanation

The quadriceps group (rectus femoris, vastus lateralis, vastus medialis, vastus intermedius) is responsible for knee extension.

Which muscle is primarily responsible for initiating knee flexion from full extension (unlocking the knee)?

• Rectus femoris

• Popliteus

• Gastrocnemius

• Gracilis

Answer explanation

The popliteus unlocks the knee by medially rotating the tibia (or laterally rotating the femur) to initiate flexion from full extension.

Which of the following muscles is innervated by the femoral nerve?

• Biceps femoris

• Vastus medialis

• Semimembranosus

• Gastrocnemius

Answer explanation

The femoral nerve supplies all quadriceps muscles and the sartorius.
The hamstrings (biceps femoris, semimembranosus) are innervated by the sciatic nerve, and gastrocnemius by the tibial nerve.

Which of the following muscles is innervated by the obturator nerve?

• Popliteus

• Biceps femoris

• Gracilis

• Vastus intermedius

The short head of the biceps femoris receives its innervation from which part of the sciatic nerve?

• Tibial portion

• Fibular (common peroneal) portion

• Obturator nerve

• Femoral nerve

Which of the following muscles originates from the anterior inferior iliac spine (AIIS)?

• Rectus femoris

• Sartorius

• Vastus lateralis

• Semitendinosus

Where does the patellar tendon insert?

• Tibial condyle

• Tibial tuberosity

• Fibular head

• Pes anserine

Which group of muscles inserts together at the pes anserine on the medial surface of the tibia?

• Quadriceps femoris

• Hamstrings (all heads)

• Sartorius, gracilis, semitendinosus

• Gastrocnemius, popliteus, plantaris

A runner reports difficulty fully extending the knee after surgery. Strength testing shows weakness in the quadriceps, and sensory loss occurs on the anterior thigh. Which nerve is most likely affected?

• Femoral nerve

• Tibial nerve

• Obturator nerve

• Sciatic nerve

A soccer player experiences pain and weakness when flexing the knee and externally rotating the tibia. Which muscle is most likely injured?

• Semitendinosus

• Gracilis

• Biceps femoris

• Popliteus