Muscles of the Leg Flashcards

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Questions and Answers

What are the 3 muscles of the superficial posterior compartment of the leg from superficial to deep?

The gastrocnemius, the soleus, and the plantaris.

What is the origin of the gastrocnemius?

Medial and lateral supracondylar ridges.

What is the insertion of the gastrocnemius?

Tendon expansion into middle posterior surface of calcaneus.

What is the action of the gastrocnemius muscle?

Plantarflexion, slight inversion of the foot, and flexion of the knee. Signup and view all the answers

Which is an important function (not action) of the gastrocnemius?

Knee stability. Signup and view all the answers

What nerve innervates the gastrocnemius, and what is its primary myotome?

Tibial nerve (S2). Signup and view all the answers

Which muscle of the superficial posterior compartment of the shank is biarticular?

The gastrocnemius. Signup and view all the answers

What action can a muscle perform if it is considered an 'anti-gravity' muscle?

Plantarflexion. Signup and view all the answers

What is the origin of the soleus muscle?

Proximal, posterior surface of fibula and tibia. Signup and view all the answers

What is the insertion of the soleus muscle?

Calcaneal tendon (makes up posterior aspect). Signup and view all the answers

What is the action of the soleus?

Plantarflexes foot. Signup and view all the answers

What nerve innervates the soleus, and what is its primary myotome?

The tibial nerve (S2). Signup and view all the answers

What is the origin of the plantaris muscle?

Lateral condyle of femur. Signup and view all the answers

What is the insertion of the plantaris muscle?

Can attach by the calcaneal tendon, or directly into the posterior, medial calcaneus. Signup and view all the answers

What is the action of the plantaris muscle?

Plantarflexion of the ankle, and flexion of the knee joint. Signup and view all the answers

What nerve innervates the plantaris muscle, and what is its primary myotome?

The tibial nerve (S2). Signup and view all the answers

Which muscle of the superficial posterior compartment of the shank is important for surgery, and why?

The plantaris muscle can be harvested for use in surgery in another part of the body as it does not have a major role in leg function. Signup and view all the answers

What muscle is the extensor digitorum longus analogous to in the upper extremity?

The extensor digitorum (communis). Signup and view all the answers

What is the origin of the extensor digitorum longus muscle?

Lateral condyle of tibia, and proximal 3/4 of anterior aspect of fibular shaft, and the adjacent interosseous membrane. Signup and view all the answers

What is the insertion of the extensor digitorum longus?

The posterior aspects of the base of the 2nd and 3rd phalanges of the lesser toes. Signup and view all the answers

What is the action of the extensor digitorum longus?

Controls the extensor expansion of the foot. Extends MTP joints, and by continued action: dorsiflexes the ankle, and everts the foot. Signup and view all the answers

What nerve innervates the extensor digitorum longus, and what is the muscle's primary myotome?

The deep peroneal nerve (L5 & S1). Signup and view all the answers

What muscle is the peroneus tertius analogous to in the upper extremity?

The extensor digiti minimi. Signup and view all the answers

What is the origin of the peroneus tertius?

The distal anterior fibula, interosseous membrane, and extensor digitorum longus. Signup and view all the answers

What is the insertion of the peroneus tertius?

The dorsal surface of the cuboid/ 5th metatarsal. Signup and view all the answers

What is the action of the peroneus tertius?

Eversion of foot, and dorsiflexion of the ankle. Signup and view all the answers

What nerve innervates the peroneus tertius muscle, and what is its primary myotome?

Deep peroneal nerve (L5 & S1). Signup and view all the answers

What is the origin of the tibialis posterior?

Posterior proximal leg. Signup and view all the answers

What is the insertion of the tibialis posterior?

Plantar, medial side of foot. Signup and view all the answers

What is the action of the tibialis posterior?

Inverts foot and assists gastrocnemius and soleus in plantarflexion of foot. Signup and view all the answers

What nerve innervates the tibialis posterior, and is its primary myotome(s)?

The tibial nerve (L4 & L5). Signup and view all the answers

Study Notes

Superficial Posterior Compartment Muscles

Three muscles: gastrocnemius, soleus, plantaris.
Gastrocnemius originates from medial and lateral supracondylar ridges.
Gastrocnemius inserts via tendon into the middle posterior surface of the calcaneus.
Gastrocnemius actions: plantarflexion, slight inversion of foot, and knee flexion.
Important function of gastrocnemius: stability of the knee.
Innervated by the tibial nerve (S2).
Gastrocnemius is a biarticular muscle, affecting both the ankle and knee joints.

Soleus Muscle

Originates from the proximal, posterior surface of fibula and tibia.
Inserts into the calcaneal tendon, forming the posterior aspect of the leg.
Soleus primarily plantarflexes the foot.
Innervated by the tibial nerve (S2).

Plantaris Muscle

Originates from the lateral condyle of the femur.
Inserts at the posterior, medial calcaneus or via the calcaneal tendon.
Action includes weak plantarflexion of the ankle and knee flexion.
Innervated by the tibial nerve (S2).
Plantaris can be harvested for surgical purposes due to its minor role in function.

Anterior Compartment Muscles

Extensor digitorum longus is analogous to the upper extremity's extensor digitorum (communis).
Originates from the lateral condyle of the tibia and the proximal anterior fibula.
Inserts on the posterior aspects of the bases of the 2nd and 3rd phalanges of the lesser toes.
Actions include controlling extensor expansion, extending MTP joints, dorsiflexing the ankle, and everting the foot.
Innervated by the deep peroneal nerve (L5 & S1).

Peroneus Tertius Muscle

Analagous to the extensor digiti minimi in the upper extremity.
Originates from the distal anterior fibula and interosseous membrane.
Inserts on the dorsal surface of the cuboid and 5th metatarsal.
Actions: eversion of the foot and dorsiflexion of the ankle.
Innervated by the deep peroneal nerve (L5 & S1).

Tibialis Posterior Muscle

Originates from the posterior proximal leg.
Inserts on the plantar, medial side of the foot.
Actions include foot inversion and assisting in plantarflexion alongside the gastrocnemius and soleus.
Innervated by the tibial nerve (L4 & L5).

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Description

Test your knowledge of the muscles in the leg with these flashcards. This quiz covers the superficial posterior compartment, including origins and insertions of key muscles such as the gastrocnemius. Perfect for students of anatomy looking to reinforce their understanding.