LEA Quiz 8 Flashcards
What are the boundaries of the anterior compartment of the leg?
crural fascia anteriorly, interosseus mem posteriorly, lateral surface of the tibia medially, medial surface of the fibula laterally, ant intermuscular septum laterally
Which border of the tibia do muscles NOT originate from?
Medial
What action and innervation correspond with all four anterior compartment muscles?
Deep fibular ( peroneal) nerve innervation and Dorsiflexion of the ankle
What location do all four anterior muscles have an attachment site and what artery do all four anterior muscles receive their blood supply?
All four muscles have site of origin on the interosseus membrane and the main blood supply is the anterior tibial artery.
What are the origins of tib anterior muscle
lateral condyle of the tibia, superior 1/2 of lateral surface of the tibia, interosseus membrane
Where does tibialis anterior insert?
medial and plantar surfaces of medial cuneiform and medial surface of the base of the 1st MT, passes superior and inferior extensor retinaculum
What is the action of tib anterior?
dorsiflexes ankle and INVERTS foot*
The tib anterior passes deep to what retinacula ?
superior extensor ret and inferior extensor retinac
What are two unique features of tib anterior muscle?
most medial muscle, ONLY muscle of ant comp to insert on plantar aspect of the foot, ONLY inverter of the ant compartment, strongest ankle dorsiflexor
What are the origins of extensor digitorum longus?
crural fascia, ant crural intermuscular septum, lateral condyle of the tibia, superior 3/4 of medial surface of fibula, interrosseus mem. origin more distal /inferior than other muscles
What is the insertion of EDL?
middle/distal phalanges of 2-5 digits, divides into 4 tendons at the ankle
What is the primary action of the EDL?
Dorsiflexion of the ankle, dorsiflexes 2-5th digits, weak evertor
What are several highlights of EDL?
no origin on the tibial shaft, just lateral condyle of tibia, majority of origin is from fibular shaft, MOST LATERAL muscle in ANTERIOR COMP**, divides into 4 tendons at the level of the ankle
What are the extensor expansions formed by?
EDL tendons - allows EDL to extend proximal phalanx to which tendon has no attachment, controls actions of interossei and lumbrical muscles****
What are the parts of the extensor expansion?
extensor sling and extensor wing/hood . AT PP head, combined tendons trifurcate into 1 middle, 1 lateral, and 1 medial slips . Middle slip attaches to IP , medial/lateral slips reunite and attach to DP
What are the origins of EHL?
middle part of ant surface of fibula, interosseus membrane
Where does EHL insert
base ( dorsal aspect) of distal phalanx of hallux
What are the actions of EHL?
dorsiflexes ankle, dorsiflexes hallux, no inversion
EHL passes deep to what retinacula?
Superior extensor retinaculum, inferior extensor retinaculum
What are some highlights of the EHL?
Origin is inf/distal to TA/EDL , not from proximal aspect of the leg, NO ORIGIN from Tibia, just fibula and inteross mem. *** DEEPEST muscle in the ant compartment, contributes to the formation of extensor expansion that covers dorsum of hallux
What is the function of the extensor expansion that covers the dorsum of the hallux?
anchors EHL tendon in place, Extensor hallucis capsularis
What is the extensor hallucis capsularis?
medial tendinous slip originating from the EHL or TA that inserts into the dorsomedial aspect of 1st MPJ capsule , May retract MPJ capsule to avoid impingement during MPJ dorsiflexion
What are the origins of fibularis tertius ?
anterior crural interosseus septum, inferior 1/3 of ant surface of fibula, interosseus membrane, ususally fused with EDL
What is the insertion of fibularis tertius?
dorsum of base of 5th MT


