ANAT337-L Muscles of Leg

Tibialis anterior

muscle of anterior compartment of the leg

• action: dorsiflexion and inversion of ankle

• innervation: deep fibular nerve

• blood supply: anterior tibial artery

Extensor digitorum longus

muscle of anterior compartment of leg

• action: dorsiflexion and weak eversion of ankle, extension of MIP, DIP, and PIP of toes 2-5

• innervation: deep fibular nerve

• blood supply: anterior tibial artery

Extensor hallucis longus

muscle of anterior compartment of leg

• action: dorsiflexion and weak inversion of the ankle, extension of MIP and IP of great toe

• innervation: deep fibular nerve

• blood supply: anterior tibial artery

Fibularis tertius

muscle of anterior compartment of leg

• action: dorsiflexion and weak eversion of ankle

• innervation: deep fibular nerve

• blood supply: anterior tibial artery

Deep fibular nerve, anterior tibial artery

What is the neurovasculature for the anterior compartment of the leg?

Fibularis longus

muscle of the lateral compartment of the leg

• action: eversion and assistance in plantar flexion of ankle

• innervation: superficial fibular nerve

• blood supply: fibular artery

Fibularis brevis

muscle of the lateral compartment of the leg

• action: eversion and assistance in plantar flexion of ankle

• insertion: base of 5th metatarsal

• innervation: superficial fibular nerve

• blood supply: fibular artery

Superficial fibular nerve, fibular artery

What is the neurovasculature for the lateral compartment of the leg?

Gastrocnemius

muscle of superficial posterior compartment of leg

• action: plantar flexion of ankle and knee flexion

• insertion: calcaneus (via Achilles tendon)

• innervation: tibial nerve

• blood supply: posterior tibial artery

Soleus

muscle of superficial posterior compartment of leg

• action: plantar flexion of ankle

• insertion: calcaneus (via Achilles tendon)

• innervation: tibial nerve

• blood supply: posterior tibial artery

Plantaris

muscle of superficial posterior compartment of leg with longest tendon

• action: weak knee flexion and plantar flexion of ankle

• innervation: tibial nerve blood

• supply: posterior tibial artery

Popliteus

muscle of deep posterior compartment of leg

• action: medially rotates tibia to unlock knee from full extension (aids in beginning of flexion)

• innervation: tibial nerve

• blood supply: posterior tibial artery

Tibialis posterior

muscle of deep posterior compartment of leg

• action: plantar flexion and inversion of ankle

• innervation: tibial nerve

• blood supply: posterior tibial artery

Flexor hallucis longus

muscle of deep posterior compartment of leg

• action: plantar flexion of ankle and flexion of MTP and IP of great toe

• innervation: tibial nerve

• blood supply: posterior tibial artery

Flexor digitorum longus

muscle of deep posterior compartment of leg

• action: plantar flexion of ankle and flexion of MTP, PIP, and DIP of joints 2-5

• innervation: tibial nerve

• blood supply: posterior tibial artery

Tibial nerve, posterior tibial artery

What is the neurovasculature for the posterior compartment of the leg (superficial and deep)?

Extensor hallucis brevis

muscle of dorsal aspect of foot

• action: extension of MTP of great toe

• innervation: deep fibular nerve

Extensor digitorum brevis

muscle of dorsal aspect of foot

• action: extension of MTP and PIP joints of toes 2-4

• innervation: deep fibular nerve

Pes anserine

shared insertion of sartorius, semitendinosus, and gracilis

Osteochondroma

most common non-cancerous bone growth that occurs between ages 10-50

overgrowth of cartilage and bone near epiphyseal plate

Knee joint

modified hinge joint between femur and tibia that allows for some rotation in terminal extension

surrounded by articular capsule

Femur

Patella articulates with ____ only.

Medial meniscus

ligament of the knee that is C-shaped, attached to MCL

deepens the articular surface and aids in shock absorption;

inner margin is free and avascular

Lateral meniscus

ligament of the knee that is 4/5 a circle

deepens the articular surface and aids in shock absorption

inner margin is free and avascular

ACL

cruciate ligament of knee that attaches to lateral femoral condyle and anterior tibial plateau

connected with medial meniscus (injuries)

provide rotational stability and prevent anterior/posterior translation of the tibia on the femur

inside fibrous capsule but outside synovial capsule

PCL

cruciate ligament of knee that attaches to medial femoral condyle and posterior tibial plateau

thicker and stronger than other cruciate ligament

provide rotational stability and prevent anterior/posterior translation of the tibia on the femur

inside fibrous capsule but outside synovial capsule

Lateral collateral ligament

ligament of the knee that prevents varus force

Medial collateral ligament

ligament of the knee that prevents valgus force

ACL, MCL, medial meniscus

• holding femur and pulling tibia anteriorly tasks ACL

What are the commonly injured ligaments in the unhappy triad? What is the mechanism of their injury?

Bursae

accessory structure of the knee that prevents friction

~12 in knee

Infrapatellar fat pad

accessory structure of the knee that is malleable and acts as a cushion

Genu valgum

angle of inclination of knee that results in decreased angle between them

“knock knees”

Genu varum

angle of inclination of knee that results in increased angle between them

“Bow legged”

Compartment syndrome

when pressure in compartment of leg with no way to relieve it

cuts off blood supply and innervation, can lead to amputation

Ankle joint

hinge joint composed of two articulations

• distal tibia and talus

• distal fibula and lateral aspect of talus

contains anterior and posterior tibiofibular ligaments, and laterally posterior and anterior talofibular ligaments, and calcaneofibular ligament

Deltoid ligament

medial ligament of talocrural joint; broader and stronger