Lower Leg Muscles (with actions and labels)

Summary

This script provides a detailed explanation of the muscles involved in foot and ankle movements, focusing on their actions and locations. It highlights the dorsiflexors and plantar flexors, describing their attachments and functions. Muscles like the tibialis anterior, extensor digitorum longus, fibularis longus, and brevis are examined in terms of dorsiflexion, plantar flexion, inversion, and eversion. The script also covers the gastrocnemius, soleus, plantaris, and popliteus muscles, exploring their role in knee flexion and ankle movement. It emphasizes the anatomical relationships and actions of these muscles in both the foot and knee regions.

Takeaways

• 😀 Muscles inserting onto the top of the foot will dorsiflex the foot, while those on the bottom will plantar flex.
• 😀 Inversion and eversion depend on muscle attachments; lateral side muscles evert the foot, and medial side muscles invert it.
• 😀 Tibialis anterior and extensor digitorum longus dorsiflex the foot because they attach to the top, while fibularis longus and brevis plantar flex due to their attachment on the bottom.
• 😀 Fibularis longus and brevis are involved in both plantar flexion and eversion due to their lateral attachment on the foot.
• 😀 Tibialis anterior, located on the medial side of the foot, inverts and dorsiflexes the foot.
• 😀 Extensor digitorum longus extends the toes, in addition to dorsiflexing the foot.
• 😀 The gastrocnemius is a large muscle that assists with both plantar flexion and knee flexion, and it is made up of the lateral and medial heads.
• 😀 The triceps surae (gastrocnemius and soleus) together contribute to plantar flexion, with the plantaris also aiding this function.
• 😀 The popliteus muscle only helps with knee flexion and does not affect the ankle as it does not cross the ankle joint.
• 😀 Deeper muscles like flexor digitorum longus, tibialis posterior, and flexor hallucis longus are responsible for plantar flexion and inversion of the foot.

Q & A

What is the main idea behind understanding the actions of muscles in relation to the foot?

The main idea is to remember where the muscles are inserting and where they are coming from. Muscles that insert on the top of the foot generally dorsiflex, while those that insert on the bottom plantar flex. The direction of movement also depends on whether the muscle is connected to the medial or lateral side of the foot.

What do dorsiflexors do, and where are they located?

Dorsiflexors are muscles that help pull the foot upward, towards the shin. These muscles, such as the tibialis anterior and extensor digitorum longus, are located at the front of the lower leg and insert on the top of the foot.

What is the function of plantar flexors and where are they located?

Plantar flexors help point the foot downward, away from the shin. Muscles like the fibularis longus and brevis, which are located on the lateral side of the lower leg, insert on the bottom of the foot and perform this action.

How do inversion and eversion of the foot occur?

Inversion and eversion are movements of the foot that involve turning it inward or outward. Muscles attached to the medial side of the foot cause inversion (e.g., tibialis anterior), while muscles attached to the lateral side of the foot cause eversion (e.g., fibularis longus and brevis).

What is the role of the extensor digitorum longus muscle?

The extensor digitorum longus is primarily responsible for extending the toes and also contributes to dorsiflexion of the foot, as it attaches to the top of the foot.

What are the fibularis longus and brevis muscles responsible for?

The fibularis longus and brevis muscles are responsible for plantarflexion and eversion of the foot. These muscles insert on the bottom of the foot and are attached more laterally.

What is the function of the gastrocnemius muscle?

The gastrocnemius muscle is a major plantarflexor of the foot and also acts as a knee flexor because it crosses the knee joint. It is part of the triceps surae group, along with the soleus muscle.

How does the plantaris muscle contribute to foot movement?

The plantaris muscle works as a plantarflexor and contributes to knee flexion. It runs alongside the gastrocnemius and inserts on the Achilles tendon.

What is the function of the popliteus muscle?

The popliteus muscle helps in flexing the knee joint but does not affect the ankle as it does not cross the ankle joint. It inserts onto the tibia.

How do the deeper muscles like the flexor digitorum longus, tibialis posterior, and flexor hallucis longus contribute to foot movement?

These deeper muscles, which insert on the lateral side of the foot, contribute to plantarflexion and inversion of the foot. They do not affect the knee joint as they do not cross it.