Fascia and Muscles of the Leg Flashcards
Deep fascia of the leg
“Crural fascia”
- Continuous with the fascia lata of the thigh proximally
Attachments of crural fascia
o Patella o Patellar ligament o Tibial tuberosity o Condyles of tibia o Head of fibula
Crural fascia forms the ________ posteriorly
Popliteal fascia
Crural fasica receives fibers from 5 tendons
o Biceps femoris o Sartorius o Gracilis o Semitendinosus o Semimembranosus
Subcutaneous periosteum of the tibia
o Continuous with the deep fascia anteriorly
o Thicker proximally
o Forms retinacula of the ankle distally
o Serves as partial origin for: tibialis anterior and extensor digitorum longus
Deep surface of periosteum gives rise to
- Anterior intermuscular septa
- Posterior intermuscular septa
- Deep transverse fascia
Anterior and posterior intermuscular septa
NOTE: anterior and posterior intermuscular septa separate peroneus longus and brevis from each other and from muscles of the anterior and posterior crural compartments
Muscles of the anterior crural compartment
o Tibialis anterior o Extensor hallucis longus o Extensor hallucis capsularis o Extensor digitorum longus o Peroneus (fibularis) tertius
Muscles of the lateral crural compartment
o Peroneus (fibularis) longus o Peroneus (fibularis) brevis
Muscles of the posterior crural compartment - superficial group
- Gastrocnemius
- Soleus
- Plantaris
Muscles of the posterior crural compartment - deep group
- Popliteus
- Flexor hallucis longus
- Flexor digitorum longus
- Tibialis posterior
Tibialis anterior origin
Four origins:
- Lateral condyle of tibia
- Lateral surface of the tibia
- Interosseous membrane
- Deep crural fascia
Tibialis anterior insertion
The thick muscle descends vertically to its insertion on the…
- Medial plantar surface of the medial cuneiform
- Base of first metatarsal
Nerve supply to tibialis anterior
Deep peroneal (fibular) nerve
Function of tibialis anterior
- Dorsiflexor and inverter of the ankle
- Also a supinator (adduction, inversion) of the intertarsal joints
Origin of extensor hallucis longus
Middle 2/3 of the anterior surface of the fibula (medial to the origin of the extensor digitorum longus)
- Also has an accessory origin from the interosseous membrane
Insertion of extensor hallucis longus
Base of distal phalanx of the first digit, with an additional slip of insertion into the base of the first metatarsal
Nerve supply to extensor hallucis longus
Deep peroneal (fibular) nerve
Function of extensor hallucis longus
Three functions:
- Extension of the first metatarsophalangeal joint
- Dorsiflexion of the ankle joint
- Supination at the intertarsal joints
Notes on extensor hallucis longus
Located just lateral to the tibialis anterior
- Distally, the anterior tibial vessels and deep peroneal nerve lie between it and the tibialis anterior
- Distal to the inferior extensor retinaculum, it passes from lateral to medial, superficial to these neurovascular structures
Extensor hallucis capsularis
Accessory muscle
Extensor hallucis capsularis origin
Arises from an extension of the extensor hallucis longus tendon
Extensor hallucis capsularis insertion
Passes distally to insert on the medial surface of the capsule of the first MPJ
Extensor hallucis capsularis function
To lift the capsule out of the joint to prevent the entrapment of the capsule
Extensor digitorum longus origin
Five origins:
- Lateral condyle of the tibia
- Head and upper ¾ of the anterior surface of the fibula
- Interosseous membrane
- Deep fascia
- Anterior intermuscular septum (between it and peroneus longus)
Extensor digitorum longus insertion
Extensor expansion of the 2nd, 3rd, 4th and 5th digits
Extensor digitorum longus nerve supply
Deep peroneal (fibular) nerve
Extensor digitorum longus function
Extension of MPJs of the four lateral digits
- Also dorsiflexes and everts the ankle
- Pronates (abduction and eversion) of the intertarsal joints
- Think “PEDAb”)
Extensor digitorum longus notes
Found lateral to the extensor hallucis longus on the lateral extreme of the anterior crural compartment
Peroneus (fibularis) tertius origin
Lower 1/3 of anterior surface of the fibula
Peroneus (fibularis) tertius insertion
Follows extensor digitorum longus to its insertion on the base of the 5th met
Peroneus (fibularis) tertius nerve supply
Deep peroneal (fibular) nerve
Peroneus (fibularis) tertius function
- Dorsiflexor and everter of the ankle
- Pronator of intertarsal joints
Peroneus (fibularis) tertius notes
Peroneus tertius is an inconstant muscle that can be considered to be part of the extensor digitorum longus