Anatomy & Physiology: The Unity of Form and Function, 7th Edition

Published by McGraw-Hill Education
ISBN 10: 0073403717
ISBN 13: 978-0-07340-371-7

Chapter 10 - Section 10.5 - Study Guide - Assess Your Learning Outcomes - Page 372: 8

Answer

The leg muscles are categorized into three main compartments based on their functions and anatomical locations: the anterior, posterior, and lateral 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 leg primarily function to dorsiflex the foot (lifting the foot and toes toward the shin) and extend the toes. These muscles are important for activities like walking and running. - Key muscles in the anterior compartment include: - **Tibialis Anterior:** Located on the front of the shin, this muscle is responsible for dorsiflexion and inversion of the foot. - **Extensor Digitorum Longus:** This muscle extends the toes and dorsiflexes the foot. - **Extensor Hallucis Longus:** It primarily extends the big toe and assists in dorsiflexing the foot. - **Peroneus Tertius (Fibularis Tertius):** This muscle, in some individuals, is found in the anterior compartment and assists in dorsiflexion and eversion of the foot. 2. **Posterior Compartment (Flexor Compartment):** - The muscles in the posterior compartment of the leg primarily function to plantarflex the foot (pointing the foot downward) and flex the toes. These muscles are crucial for activities like pushing off the ground during walking and jumping. - Key muscles in the posterior compartment include: - **Gastrocnemius:** This is the large calf muscle responsible for plantarflexion of the foot and flexion of the knee. - **Soleus:** Located deep to the gastrocnemius, it also plays a significant role in plantarflexion. - **Plantaris:** A slender muscle that assists in plantarflexion. - **Popliteus:** Located behind the knee joint, this muscle unlocks the knee joint from a fully extended position. - **Flexor Digitorum Longus:** This muscle flexes the toes and plantarflexes the foot. - **Flexor Hallucis Longus:** It primarily flexes the big toe and plantarflexes the foot. - **Tibialis Posterior:** This muscle assists in plantarflexion and inversion of the foot and also helps support the arch of the foot. 3. **Lateral Compartment (Evertor Compartment):** - The muscles in the lateral compartment of the leg primarily function to evert the foot (turning the sole of the foot outward). These muscles are involved in stabilizing the ankle during walking and running. - Key muscles in the lateral compartment include: - **Peroneus (Fibularis) Longus:** This muscle everts the foot and also provides support to the arch of the foot. - **Peroneus (Fibularis) Brevis:** It works in conjunction with the peroneus longus to evert the foot. - **Peroneus (Fibularis) Tertius:** In some individuals, this muscle is found in the anterior compartment but assists in eversion and dorsiflexion of the foot. These three compartments of leg muscles play essential roles in lower limb movements, stability, and overall functionality of the lower extremities. Understanding their functions and relationships is important in various fields, including anatomy, sports medicine, and physical therapy.

Work Step by Step

The leg muscles are categorized into three main compartments based on their functions and anatomical locations: the anterior, posterior, and lateral 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 leg primarily function to dorsiflex the foot (lifting the foot and toes toward the shin) and extend the toes. These muscles are important for activities like walking and running. - Key muscles in the anterior compartment include: - **Tibialis Anterior:** Located on the front of the shin, this muscle is responsible for dorsiflexion and inversion of the foot. - **Extensor Digitorum Longus:** This muscle extends the toes and dorsiflexes the foot. - **Extensor Hallucis Longus:** It primarily extends the big toe and assists in dorsiflexing the foot. - **Peroneus Tertius (Fibularis Tertius):** This muscle, in some individuals, is found in the anterior compartment and assists in dorsiflexion and eversion of the foot. 2. **Posterior Compartment (Flexor Compartment):** - The muscles in the posterior compartment of the leg primarily function to plantarflex the foot (pointing the foot downward) and flex the toes. These muscles are crucial for activities like pushing off the ground during walking and jumping. - Key muscles in the posterior compartment include: - **Gastrocnemius:** This is the large calf muscle responsible for plantarflexion of the foot and flexion of the knee. - **Soleus:** Located deep to the gastrocnemius, it also plays a significant role in plantarflexion. - **Plantaris:** A slender muscle that assists in plantarflexion. - **Popliteus:** Located behind the knee joint, this muscle unlocks the knee joint from a fully extended position. - **Flexor Digitorum Longus:** This muscle flexes the toes and plantarflexes the foot. - **Flexor Hallucis Longus:** It primarily flexes the big toe and plantarflexes the foot. - **Tibialis Posterior:** This muscle assists in plantarflexion and inversion of the foot and also helps support the arch of the foot. 3. **Lateral Compartment (Evertor Compartment):** - The muscles in the lateral compartment of the leg primarily function to evert the foot (turning the sole of the foot outward). These muscles are involved in stabilizing the ankle during walking and running. - Key muscles in the lateral compartment include: - **Peroneus (Fibularis) Longus:** This muscle everts the foot and also provides support to the arch of the foot. - **Peroneus (Fibularis) Brevis:** It works in conjunction with the peroneus longus to evert the foot. - **Peroneus (Fibularis) Tertius:** In some individuals, this muscle is found in the anterior compartment but assists in eversion and dorsiflexion of the foot. These three compartments of leg muscles play essential roles in lower limb movements, stability, and overall functionality of the lower extremities. Understanding their functions and relationships is important in various fields, including anatomy, sports medicine, and physical therapy.
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