Chapter 10 - Section 10.5 - Study Guide - Assess Your Learning Outcomes - Page 372: 4

The thigh muscles are categorized into three main compartments based on their functions and anatomical locations: the anterior (extensor), medial (adductor), and posterior (flexor) compartments. Each compartment contains specific groups of muscles that perform distinct actions. Let's explore these compartments and their associated muscles: 1. **Anterior Compartment (Extensor Compartment):** - The muscles in the anterior compartment of the thigh primarily function to extend and straighten the leg at the knee joint. These muscles are involved in activities like walking, running, and kicking. - Key muscles in the anterior compartment include: - **Quadriceps Femoris Group:** This group consists of four muscles: - **Rectus Femoris:** This muscle is the only one of the quadriceps that also flexes the hip. - **Vastus Lateralis:** Located on the outer side of the thigh. - **Vastus Medialis:** Located on the inner side of the thigh. - **Vastus Intermedius:** Positioned deep between the vastus lateralis and vastus medialis. - These muscles collectively extend the knee joint. 2. **Medial Compartment (Adductor Compartment):** - The muscles in the medial compartment of the thigh primarily function to adduct the thigh, bringing it toward the midline of the body. They also assist in hip flexion and extension. - Key muscles in the medial compartment include: - **Adductor Longus:** Located on the inner thigh. - **Adductor Brevis:** Also positioned on the inner thigh. - **Adductor Magnus:** A larger muscle with both adductor and hamstring components. - **Gracilis:** A slender muscle located on the inner thigh. - **Pectineus:** Located near the hip joint and has both adductor and flexor functions. - These muscles are important for activities involving squeezing the thighs together and maintaining balance. 3. **Posterior Compartment (Flexor Compartment):** - The muscles in the posterior compartment of the thigh primarily function to flex the knee joint and extend the hip joint. They are essential for activities like walking, running, and jumping. - Key muscles in the posterior compartment include: - **Hamstring Group:** This group consists of three muscles: - **Biceps Femoris:** Comprising both a long head and a short head. - **Semitendinosus:** A long, slender muscle. - **Semimembranosus:** A broader, membranous muscle. - These muscles collectively flex the knee and extend the hip. - **Popliteus:** A smaller muscle located at the back of the knee joint, assisting in knee flexion and unlocking the knee from a fully extended position. - **Gastrocnemius:** The calf muscle that flexes the knee and plantarflexes the ankle. These three compartments of thigh muscles work in coordination to provide the necessary movements and stability for various lower limb activities. Understanding their functions and relationships is crucial in the fields of anatomy, physiology, and physical therapy.

The thigh muscles are categorized into three main compartments based on their functions and anatomical locations: the anterior (extensor), medial (adductor), and posterior (flexor) compartments. Each compartment contains specific groups of muscles that perform distinct actions. Let's explore these compartments and their associated muscles: 1. **Anterior Compartment (Extensor Compartment):** - The muscles in the anterior compartment of the thigh primarily function to extend and straighten the leg at the knee joint. These muscles are involved in activities like walking, running, and kicking. - Key muscles in the anterior compartment include: - **Quadriceps Femoris Group:** This group consists of four muscles: - **Rectus Femoris:** This muscle is the only one of the quadriceps that also flexes the hip. - **Vastus Lateralis:** Located on the outer side of the thigh. - **Vastus Medialis:** Located on the inner side of the thigh. - **Vastus Intermedius:** Positioned deep between the vastus lateralis and vastus medialis. - These muscles collectively extend the knee joint. 2. **Medial Compartment (Adductor Compartment):** - The muscles in the medial compartment of the thigh primarily function to adduct the thigh, bringing it toward the midline of the body. They also assist in hip flexion and extension. - Key muscles in the medial compartment include: - **Adductor Longus:** Located on the inner thigh. - **Adductor Brevis:** Also positioned on the inner thigh. - **Adductor Magnus:** A larger muscle with both adductor and hamstring components. - **Gracilis:** A slender muscle located on the inner thigh. - **Pectineus:** Located near the hip joint and has both adductor and flexor functions. - These muscles are important for activities involving squeezing the thighs together and maintaining balance. 3. **Posterior Compartment (Flexor Compartment):** - The muscles in the posterior compartment of the thigh primarily function to flex the knee joint and extend the hip joint. They are essential for activities like walking, running, and jumping. - Key muscles in the posterior compartment include: - **Hamstring Group:** This group consists of three muscles: - **Biceps Femoris:** Comprising both a long head and a short head. - **Semitendinosus:** A long, slender muscle. - **Semimembranosus:** A broader, membranous muscle. - These muscles collectively flex the knee and extend the hip. - **Popliteus:** A smaller muscle located at the back of the knee joint, assisting in knee flexion and unlocking the knee from a fully extended position. - **Gastrocnemius:** The calf muscle that flexes the knee and plantarflexes the ankle. These three compartments of thigh muscles work in coordination to provide the necessary movements and stability for various lower limb activities. Understanding their functions and relationships is crucial in the fields of anatomy, physiology, and physical therapy.