Chapter 10 - Section 10.5 - Study Guide - Assess Your Learning Outcomes - Page 372: 9

The muscles of the anterior compartment of the leg, which includes the fibularis tertius, extensor digitorum longus, extensor hallucis longus, and tibialis anterior muscles. These muscles are responsible for dorsiflexion of the foot and extension of the toes. Here's a breakdown of each of these muscles: 1. **Fibularis Tertius (Peroneus Tertius):** - **Location:** The fibularis tertius is sometimes considered part of the anterior compartment of the leg. - **Origin:** It typically originates from the lower third of the fibula (the smaller of the two lower leg bones). - **Insertion:** The muscle inserts onto the dorsal aspect (top) of the fifth metatarsal bone in the foot. - **Function:** The primary function of the fibularis tertius is dorsiflexion and eversion of the foot. It also assists in walking and stabilizing the ankle. 2. **Extensor Digitorum Longus:** - **Location:** The extensor digitorum longus is a muscle located in the anterior compartment of the leg. - **Origin:** It originates from the lateral condyle of the tibia (shinbone) and the proximal part of the fibula. - **Insertion:** The muscle inserts onto the dorsal surfaces of the middle and distal phalanges of the four smaller toes (digits 2-5). - **Function:** The primary function of the extensor digitorum longus is to extend the four smaller toes (digits 2-5) and assist in dorsiflexion of the foot. It is responsible for lifting the toes during walking and other activities. 3. **Extensor Hallucis Longus:** - **Location:** The extensor hallucis longus is also located in the anterior compartment of the leg. - **Origin:** It originates from the middle part of the fibula and the interosseous membrane between the tibia and fibula. - **Insertion:** The muscle inserts onto the dorsal surface of the distal phalanx of the big toe (digit 1). - **Function:** The primary function of the extensor hallucis longus is to extend the big toe (digit 1) and assist in dorsiflexion of the foot. It plays a role in lifting the big toe during activities such as walking and running. 4. **Tibialis Anterior:** - **Location:** The tibialis anterior is a prominent muscle in the anterior compartment of the leg. - **Origin:** It originates from the lateral surface of the tibia and the interosseous membrane between the tibia and fibula. - **Insertion:** The muscle inserts onto the medial cuneiform bone and the base of the first metatarsal bone. - **Function:** The tibialis anterior is the primary muscle responsible for dorsiflexion of the foot (lifting the foot and toes toward the shin) and inversion of the foot (turning the sole of the foot inward). It plays a crucial role in controlling the descent of the foot during activities like walking and running, as well as in maintaining balance. These muscles of the anterior compartment of the leg work together to provide dorsiflexion of the foot and extension of the toes, contributing to various movements and activities in the lower limb.

The muscles of the anterior compartment of the leg, which includes the fibularis tertius, extensor digitorum longus, extensor hallucis longus, and tibialis anterior muscles. These muscles are responsible for dorsiflexion of the foot and extension of the toes. Here's a breakdown of each of these muscles: 1. **Fibularis Tertius (Peroneus Tertius):** - **Location:** The fibularis tertius is sometimes considered part of the anterior compartment of the leg. - **Origin:** It typically originates from the lower third of the fibula (the smaller of the two lower leg bones). - **Insertion:** The muscle inserts onto the dorsal aspect (top) of the fifth metatarsal bone in the foot. - **Function:** The primary function of the fibularis tertius is dorsiflexion and eversion of the foot. It also assists in walking and stabilizing the ankle. 2. **Extensor Digitorum Longus:** - **Location:** The extensor digitorum longus is a muscle located in the anterior compartment of the leg. - **Origin:** It originates from the lateral condyle of the tibia (shinbone) and the proximal part of the fibula. - **Insertion:** The muscle inserts onto the dorsal surfaces of the middle and distal phalanges of the four smaller toes (digits 2-5). - **Function:** The primary function of the extensor digitorum longus is to extend the four smaller toes (digits 2-5) and assist in dorsiflexion of the foot. It is responsible for lifting the toes during walking and other activities. 3. **Extensor Hallucis Longus:** - **Location:** The extensor hallucis longus is also located in the anterior compartment of the leg. - **Origin:** It originates from the middle part of the fibula and the interosseous membrane between the tibia and fibula. - **Insertion:** The muscle inserts onto the dorsal surface of the distal phalanx of the big toe (digit 1). - **Function:** The primary function of the extensor hallucis longus is to extend the big toe (digit 1) and assist in dorsiflexion of the foot. It plays a role in lifting the big toe during activities such as walking and running. 4. **Tibialis Anterior:** - **Location:** The tibialis anterior is a prominent muscle in the anterior compartment of the leg. - **Origin:** It originates from the lateral surface of the tibia and the interosseous membrane between the tibia and fibula. - **Insertion:** The muscle inserts onto the medial cuneiform bone and the base of the first metatarsal bone. - **Function:** The tibialis anterior is the primary muscle responsible for dorsiflexion of the foot (lifting the foot and toes toward the shin) and inversion of the foot (turning the sole of the foot inward). It plays a crucial role in controlling the descent of the foot during activities like walking and running, as well as in maintaining balance. These muscles of the anterior compartment of the leg work together to provide dorsiflexion of the foot and extension of the toes, contributing to various movements and activities in the lower limb.