Photo 2. Erector spinae mm.

Identify the deeper muscles of the gluteal region and associated neurovasculature

Find these structures:

• • Gluteus maximus m.

  • Gluteus medius m.

  • Gluteus minimus m.

  • Piriformis m.

  • Lateral rotators of hip

    • Superior gemellus m.

    • Obturator internus m. & tendon

    • Inferior gemellus m.

    • Quadratus femoris m.

  • Superior gluteal n. & a.

  • Inferior gluteal n. & a.

  • Sciatic n.

2.) Relieve the gluteus maximus m. from its proximal attachments: ilium, sacrum & sacrotuberous ligaments, and reflect the muscle laterally. This muscle is composed of thick muscle fascicles, and may be difficult to reflect. Locate the fascial plane between the gluteus maximus and medius mm. to facilitate reflection. Do NOT cut too deep to maintain neurovasculature and the sacrotuberous ligament.

Photo 3. Gluteus maximus m. reflection lines

Note: The inferior gluteal n. (from sacral plexus) is so named, because it enters the gluteal compartment through the greater sciatic foramen, inferior to the piriformis m. The inferior gluteal n. is the sole innervation for the gluteus maximus m.

Note: The inferior gluteal a. accompanies the inferior gluteal n. It is a branch of the internal iliac a., anterior division. It supplies the inferior portions of the gluteus maximus m., and is typically the dominant supply of the muscle. The superior gluteal a. (internal iliac a., posterior division) brs. provides additional blood supply to the superior portions of the muscle.

3.) Clean and observe the boundaries of the gluteus medius m.

Photo 4. Gluteus medius m.

4.) Reflect the gluteus medius m., and locate the gluteus minimus m. and superior gluteal n. & a.

Note: The superior gluteal n. (from the sacral plexus) is so named, because it enters the gluteal compartment, through the greater sciatic foramen, superior to the piriformis m. The superior gluteal n. innervates the gluteus medius and minimus mm., as well as the tensor fasciae latae m.

Note: The superior gluteal a. accompanies the superior gluteal n. It is a branch of the internal iliac a., posterior division. It supplies superior portions of the gluteus maximus m., gluteus medius & minimus mm., and tensor fasciae latae.

Photo 5. Gluteus minimus m. and superior gluteal n. & a.

5.) Clean and identify the lateral rotators of the hip: piriformis m., superior gemellus m., obturator internus m. & tendon, inferior gemellus m., and quadratus femoris m. Locate the sciatic n. as it exits the pelvic region inferior to the piriformis m.

Note: The piriformis m. is a lateral rotator of the hip, but it is often considered independently because of it’s important position in regards to neurovasculature. It is often referred to as ‘the key to the hip.’ The piriformis muscle belly travels through the greater sciatic foramen and inserts on the greater trochanter of the femur. The superior gluteal neurovasculature enters the gluteal region superior to the piriformis m., while many neurovascular components enter the gluteal region inferior to piriformis m. - most notably, the sciatic n. and inferior gluteal neurovasculature.

 Note: The sciatic n. (the bound combination of tibial and common fibular nn.) is the largest nerve in the body and is derived L4-S3. It exits the greater sciatic foramen inferior to the piriformis m. It bifurcates (typically around the popliteal fossa) into the tibial n. (L4-S3) and common fibular n. (L4-S2).

Photo 6. Lateral rotator mm. and sciatic n.

 Locate structures of the posterior knee

Find these structures:

• • Popliteal a. & v.

  • Tendons of hamstrings

  • Capsule

  • Anterior cruciate ligament (ACL)

  • Posterior cruciate ligament (PCL)

  • Fibular (lateral) collateral ligament (LCL)

  • Tibial (medial) collateral ligament (MCL)

  • Medial meniscus

  • Lateral meniscus

6.) Locate the popliteal a. & v. in the popliteal fossa. You may see branches of the popliteal a. (five genicular aa.) supplying the knee joint.

Note: The boundaries of the popliteal fossa:

• • Hamstring mm. tendons (superomedial and superolateral)

  • Gastrocnemius m. heads (inferomedial and inferolateral)

Photo 7. Boundaries of popliteal fossa

 Note: The neurovascular structures are organized in the popliteal fossa from superficial to deep:

• • Various cutaneous nerves and superficial veins

  • Bifurcation of sciatic n.

    • Tibial n. (medial)

    • Common fibular n. (lateral)

  • Popliteal v.

  • Popliteal a.

Photo 8. Popliteal fossa

7.) UNILATERALLY, remove the plantaris m. and popliteus m., and open the joint capsule of the knee joint posteriorly.

Note: The popliteus m. is the floor of the inferior portion of the popliteal fossa. This muscle plays an important role in ‘unlocking’ the knee (lateral rotation) from an extended position, in order to allow flexion of the knee.

8.) UNILATERALLY, clean and identify the posterior and anterior cruciate ligaments from a posterior view.

Note: The posterior cruciate ligament (PCL) attaches the tibia (intercondylar area) and femur (lateral portion of medial condyle of femur), and is significantly stronger than the anterior cruciate ligament (ACL). The PCL is an important femoral stabilizer during knee flexion (e.g. walking down the stairs). This ligament also prevents posterior displacement of the tibia in relation to the femur.

Note: The anterior cruciate ligament (ACL) attaches the tibia (intercondylar area) and femur (medial portion of lateral condyle of femur), and is significantly weaker than the PCL. This ligament prevents anterior displacement of the tibia in relation to the femur.

Photo 9. Cruciate ligaments

9.) Clean and identify the fibular (lateral) and tibial (medial) collateral ligaments.

Note: The fibular (lateral) collateral ligament is a strong, cord-like ligament, connecting the femur (lateral epicondyle) to the fibular head. This ligament is wholly extracapsular with the tendon of popliteus m. passing deep to the ligament, separating it from the articular capsule and the other structures of the knee joint.

Note: The tibial (medial) collateral ligament is a thickening of the medial part of the articular capsule of the knee, and is therefore considered a capsular ligament. It is attached to the medial epicondyle of the femur and medial tibia. Of clinical relevance, the MCL is firmly attached to the medial meniscus, and these structures are commonly injured together. The ACL is in close association (but not attached) to these structures; if all three are damaged together, this is referred to as the unhappy/terrible triad.

10.) UNILATERALLY, clean and identify the medial & lateral menisci.

Note: Menisci are incomplete (crescentic) rings of fibrocartilage located in shallow articular surfaces. In the case of the knee joint, there are menisci associated with the medial and lateral condyles of the tibia. The lateral meniscus has significantly more mobility than the medial meniscus, and consequently, is less frequently damaged.

Photo 10. Collateral ligaments & menisci

Turn the donor to a supine position, and locate muscles of trunk & hip flexion

Find these structures:

• • Quadratus lumborum m.

  • Psoas major m.

11.) Clean and locate the psoas major m. and quadratus lumborum m. in the region flanking the lower back.

Note: Vertebral column and hip mm.

 Photo 11. Quadratus lumborum & psoas major mm.

Identify structures of the anterior knee

Find these structures:

• • Patella

  • Patellar tendon (ligament)

  • Infrapatellar fat pad

12.) Clean the area surrounding the superficial anterior knee, and identify the patella and patellar tendon/ligament.

Note: The patella is the largest sesamoid bone in the body, forming in the quadriceps tendon. Its posterior surface articulates with the patellar surface of the femur.

Note: The tendon of the quadriceps femoris m. (quadriceps tendon) is robust and an important stabilizer of the superior, anterior portion of the knee joint. The patellar ligament (tendon) is the continuation of this tendon to its distal attachment, tibial tuberosity of tibia. This portion of the tendon is an important stabilizer of the inferior, anterior portion of the knee joint.

Photo 12. Quadriceps femoris tendon and patellar tendon

13.) Unilaterally, cut the quadriceps femoris m. tendon superior to the patella. Reflect the tendon and patella inferiorly. Locate the infrapatellar fat pad between the patellar ligament and the joint capsule.

Note: The infrapatellar fat pad separates the patellar ligament from the actual joint capsule, and plays a similar role as the large suprapatellar bursa, which is located between the quadriceps tendon and the femur.

Photo 13. Infrapatellar fat pad

 14.) Identify structures of the knee joint from an anterior view: anterior & posterior cruciate ligaments, tibial & fibular collateral ligaments, and medial & lateral menisci. Slightly flexing the knee joint will provide a better view of these structures.

Photo 14. Anterior view of knee joint

 Photo 15. Anterior view of knee joint