1. Knee Muscular Anatomy

2. Knee Flexors

3. Semitendinosus Origin Insertion Action Nerve Supply Palpation
Lower medial facet of the lateral section of the ischial tuberosity
Insertion
Vertical line of the anterior medial superior aspect of the medial condyle of the tibia
Action
Hip Extension, Knee Flexion and Tibial Internal Rotation
Nerve Supply
Tibial Division of Sciatic Nerve
Palpation
Patient in prone with the leg partially flexed at the knee joint. Place palpating hand on the posteromedial thigh and resist flexion of the leg at the knee joint and feel for the distal tendon of the semitendinosus. Continue palpating the muscle proximally toward the ischial tuberosity.

4. Semimembranosus Origin Insertion Action Nerve Supply Palpation
Upper lateral facet of the ischial tuberosity
Insertion
Posteromedial surface of the medial tibial condyle and oblique popliteal ligament
Action
Hip Extension, Knee Flexion and Tibial Internal Rotation
Nerve Supply
Tibial Division of Sciatic Nerve
Palpation
Best palpated distally in the posterior thigh, medial to the belly of the semitendinosus, and on either side of the distal tendon of the semitendinosus. Patient in prone with the leg partially flexed at the knee joint. Palpating hand on the distal posteromedial thigh. Resist knee flexion and feel for contraction of the semimembranosus.

5. Biceps Femoris Origin Insertion Action Nerve Supply Palpation
Long Head: Lower medial facet of the ischial tuberosity and sacrotuberous ligament
Short Head: Lower half of the lateral lip of the linea aspera and the lateral supracondylar line of the femur
Insertion
Head of the fibula
Action
Hip Extension, Knee flexion and Tibial External Rotation
Nerve Supply
Long Head: Tibial Division of Sciatic Nerve
Palpation
Patient in prone with the leg partially flexed at the knee joint. Place palpating hand on the distal posterolateral thigh, resist knee flexion and feel for the distal tendon of the biceps femoris. Continue palpating the biceps femoris toward the ischial tuberosity.
Biceps Femoris

6. Gastrocnemius Origin Insertion Action Nerve Supply Palpation
Medial supracondylar ridge and adductor tubercle of the medial femur. Lateral condyle femur. Posterior capsule of the knee from oblique popliteal ligament
Insertion
Middle Part of the posterior surface of the calcaneus
Action
Ankle Plantarflexion, Knee Flexion
Nerve Supply
Tibial Nerve
Palpation
Patient in prone with the leg extended at the knee joint. Place palpating hand on the proximal posterior leg and ask the patient to actively plantarflex the foot at the ankle joint against resistance and feel for contraction of the muscle. Palpatedall the way to its distal attachment

7. Gracilis Origin Insertion Action Nerve Supply Palpation
Front body and inferior ramus of the pubis and the ramus of the ischium
Insertion
Vertical line of the upper medial surface of the tibia shaft
Action
Hip adduction. Knee Flexion and Tibial Internal Rotation
Nerve Supply
Anterior division of the obturator nerve
Palpation
Distal Tendon: Resist knee flexion and tibial IR. Tendon is medial to the tendon of semitendinosis
Proximal belly: Place thigh into hip flexion, abduction, ER. Place flat palm along adductors. Immediate muscle mass is adductor longus. Straighten knee. Mass then found posteriorly is gracilis.
Gracilis

8. Anterior superior iliac spine and area just below
Sartorius
Origin
Anterior superior iliac spine and area just below
Insertion
Vertical line of the upper medial surface of the tibia shaft. Some fibres merge with the MCL
Action
Hip flexion, external rotation and abduction. Knee flexion and tibial internal rotation.
Nerve Supply
Femoral Nerve
Palpation
Model actively holds leg in hip flexion, abduction and slight external rotation. Belly palpated close to ASIS

9. ITB Origin Insertion Action Nerve Supply Palpation
Fascia from gluteus maximus and tensor fascia latae
Insertion
Lateral femoral epicondyle and Gerdy’s tubercle of the anterolateral aspect of the tibia
Action
Assists with knee flexion atAssists with knee flexion at angles greater than 30°
Assists with knee extension at angles smaller than 30°
angles greater than 30°
Nerve Supply
N/A
Palpation

10. Popliteus Origin Insertion Action Nerve Supply Palpation
Posterior aspect of the lateral condyle of the femur
Insertion
Triangular area on the posterior surface of the tibia
Action
Lateral rotation of the femur on tibia in weight bearing. Medial Rotation of tibia on femurs in non-weight bearing. Knee flexion
Nerve Supply
Tibial Division of the Sciatic Nerve
Palpation
Tendon: Posterior to LCL and superior to the joint line. Gently resist knee flexion

11. Knee Extensors

12. Rectus Femoris Origin Insertion Action Nerve Supply Palpation
Straight Head: Anterior inferior iliac spine
Insertion
Upper border of the patella and merges around patella to form parts of the ligamentum patellae
Action
Hip flexion, Knee Extension
Nerve Supply
Femoral Nerve
Palpation
Model: Straight leg raise 

13. Tendon of rectus femoris and lateral border of the patella
Origin
Upper lateral part of the Intertrochanteric line, lower border of the greater trochanter, the lateral side of the gluteal tuberosity and upper half of the linea aspera. Also merges with the ITB
Insertion
Tendon of rectus femoris and lateral border of the patella
Action
Knee Extension
Nerve Supply
Femoral Nerve
Palpation
Patient is supine. Place palpating hand just distal to the greater trochanter and ask the patient to contract the quadriceps femoris group. Feel for contraction of the vastus lateralis and continue palpating distally toward the patella
Vastus Lateralis

14. Vastus Medialis Origin Insertion Action Nerve Supply Palpation
Lower medial end of the intertrochanteric line, medial aspect of the upper end of the shaft on the spiral line, medial lip of the linea aspera, upper 2/3 of the medial supracondylar line and medial intermuscular septum
Insertion
Tendon of rectus femoris and medial border of the patella, the anterior medial condyle of the tibia, and the tibial tuberosity
Action
Knee Extension
Nerve Supply
Femoral Nerve
Palpation
Patient in supine. Place palpating hand just proximal and medial to the patella. Ask the client to contract the quadriceps femoris group and feel for the contraction of the vastus medialis. The vastus medialis is best palpated medially in the distal 1/3 of the thigh
Vastus Medialis

15. Vastus Intermedius Origin Insertion Action Nerve Supply Palpation
Upper 2/3 of the anterior and lateral surface of the femur
Insertion
Deep surface of the rectus femoris tendon and the base of the patella
Action
Knee Extension
Nerve Supply
Femoral Nerve
Palpation
Deep and difficult to palpate. Patient in supine. Place palpating hand just proximal to the patella. Rectus femoris can be lifted and/or moved aside, the distal vastus intermedius may be palpated deep to the rectus femoris when approached from either the medial or lateral side. The direction of your pressure is directed toward the middle of the femur
Vastus Intermedius

16. Flexion Semitendinosus Semimembranosus Biceps Femoris Gastrocnemius
Gracilis
Sartorius
ITB (> 30° Flexion)
Popliteus

17. Extension Rectus Femoris Vastus Lateralis Vastus Medialis
Vastus Intermedius
ITB ( < 30° Flexion)

18. Tibial External Rotation
Biceps Femoris
ITB

19. Tibial Internal Rotation
Popliteus (Open Chain)
Semitendinosus
Semimembranosus
Gracilis
Sartorius