Myology of the Thigh and Knee

Question 1

Adductor brevis

Answer 1

• Origin: Inferior ramus of pubic bone.
• Insertion: Upper third of the medial lip of the linea
  aspera on the posterior surface.
• Action: Hip joint: majority adduction, minor flexion.
• Innervation: Obturator nerve

Question 2

Adductor Longus

Answer 2

• Origin: Anterior surface of pubis.
• Insertion: Lower two-thirds of the medial lip of the linea
  aspera on the posterior surface.
• Action: Hip joint: majority causes adduction, minor hip
  flexion.
• Innervation: Obturator nerve.

Question 3

Adductor Magnus

Answer 3

• Origin: Anterior and Inferior surface of pubis Ischial
  tuberosity (hamstring component).
• Insertion: Lower third of the medial lip of the linea
  aspera on the posterior surface, also inserts to
  adductor tubercle.
• Action: Hip joint: powerful hip adductor, some
  extension and hip flexion.
• Innervation: Obturator nerve + sciatic nerve.

Question 4

Gracilis

Answer 4

• Origin: Ischiopubic ramus.
• Insertion: Medial border of the tibia (pes anserinus
  tendon).
• Action: Hip joint flexion, adduction and internal
  rotation; Knee flexion.
• Innervation: Obturator nerve.

Question 5

Sartorius

Answer 5

• Origin: ASIS.
• Insertion: Medial border of the tibia (pes anserinus
  tendon).
• Action: Hip joint: abduction, flexion, external rotation.
  Knee joint: flexion, tibial internal rotation.
• Innervation: Femoral nerve.

Question 6

Tensor Fasciae Latae (TFL)

Answer 6

• Origin: ASIS.
• Insertion: iliotibial band, Gerdy’s tubercle.
• Action: Hip joint: flexion, internal rotation and
  abduction. Small amount of knee joint: flexion and
  external rotation.
• Innervation: Femoral nerve.

Question 7

Rectus Femoris

Answer 7

• Origin: AIIS
• Insertion: Anterior Tibial Tuberosity (Quadriceps
  tendon).
• Action: Hip joint: small flexion. Knee joint: powerful
  extension.
• Innervation: Femoral nerve.

Question 8

Vastus Intermedius

Answer 8

• Origin: Anterolateral surface of femoral shaft.
• Insertion: Anterior Tibial Tuberosity (Quadriceps
  tendon) .
• Action: Knee joint: extension.
• Innervation: Femoral nerve.

Question 9

Vastus medialis

Answer 9

• Origin: Medial lip of linea aspera and medial
  suprachondylar ridge of femur.
• Insertion: Medial retinaculum patellae. Medial border
  of quadriceps tendon and patella (Anterior Tibial
  Tuberosity)
• Action: Knee joint: extension, medial patella glide.
• Innervation: Femoral nerve.

Question 10

Vastus Lateralis

Answer 10

• Origin: Lateral lip of linea aspera, inferior portion of
  greater trochanter and intertrochanteric line.
• Insertion: Lateral retinaculum patellae. Lateral border
  of quadriceps tendon and patella (Anterior Tibial
  Tuberosity).
• Action: Knee joint: extension, lateral patella glide.
• Innervation: Femoral nerve.

Question 11

Bicep femoris (long and short head)

Answer 11

• Origin: Long: Ischial tuberosity and lower part of
  sacrotuberous ligament.
  Short: lateral lip of linea aspera.
• Insertion: Head of fibula.
• Action: Hip joint: extension.
  Knee joint: flexion, external rotation.
• Innervation: Sciatic nerve, BUT long head
  innervated by tibial branch and short head by fibular
  branch.

Question 12

Semitendinosus

Answer 12

• Origin: Ischial tuberosity.
• Insertion: Medial border of the tibia (pes anserinus
  tendon).
• Action: Hip joint: extension.
  Knee joint: flexion, internal rotation.
• Innervation: Tibial branch of sciatic nerve.

Question 13

Semimembranosus

Answer 13

• Origin: Ischial tuberosity.
• Insertion: Medial tibial condyle.
• Action: Hip joint: extension, adduction.
  Knee joint: flexion, internal rotation.
• Innervation: Tibial branch of sciatic nerve.

Question 14

Hamstring muscles

Answer 14

Biceps Femoris
Semitendinosus
Semimembranosus

Question 15

Quadricep muscles

Answer 15

Rectus Femoris
Vastus Intermedius
Vastus Medialis
Vastus Lateralis