Gluteus Maximus Muscle Function

Gluteus Maximus

• Arises from L5, S1, and S2 spinal segments
• Extends the hip, especially against gravity, during activities like standing up from a seated position or climbing stairs
• Helps in extension of the knee via its action on the iliotibial band (tract)
• Most of its muscle fibers are inserted into the iliotibial band
• Iliotibial band inserts distally on the lateral side of the tibia, just anterior to the axis of flexion/extension of the joint, causing knee extension when stretched
• Tensor fasciae latae, a muscle that arises from the anterior superior iliac spine and anterior part of the iliac crest, aids in tightening the iliotibial band
• Supplied by the inferior gluteal nerve, while tensor fasciae latae is supplied by the superior gluteal nerve
• Excessive strain on the iliotibial band can lead to pain on the lateral aspect of the knee

Compartments of the Thigh

• The thigh contains three groups of muscles divided by fascial septae: anterior, medial (or adductor), and posterior compartments
• Anterior compartment contains powerful anti-gravity extensor muscles of the knee and some flexors of the hip
• Medial compartment muscles perform the movement of adduction of the hip
• Posterior compartment muscles are both flexors of the knee and extensors of the hip

Intermuscular Septae of the Thigh

• Medial, lateral, and posterior intermuscular septae separate the compartments

Anterior Compartment of the Thigh

• Contains flexors of the hip, flexors of the knee, and a powerful extensor of the knee
• All muscles supplied by the femoral nerve and receive a blood supply from the femoral artery

Medial Compartment of the Thigh

• Contains adductor muscles of the hip
• Muscles innervated by the obturator nerve and receive a blood supply from the perforating branches of the profunda femoris
• Important in walking, pulling the pelvis over the thigh for balance and stability
• Used to pull the limbs together, allowing the knees and ankles to come into alignment for walking

Posterior Compartment of the Thigh (Hamstrings)

• Contains biceps femoris, semimembranosus, semitendinosus
• Muscles have a common tendinous attachment to the ischial tuberosity
• Supplied by the tibial nerve (except short head of biceps - Common fibular n.)
• Blood supply from the profunda femoris art.

Rotation of the Knee Joint

• Medial rotation: pes anserinus group (sartorius, gracilis, semitendinosus) and semimembranosus
• Lateral rotation: biceps femoris muscle and popliteus (at the back of the knee)

Femoral Triangle and Popliteal Fossa

• Will be discussed in the final section of the lecture

Learn about the role of the gluteus maximus muscle in hip extension, its spinal segments, and how it differs from hamstrings in walking and other activities.