5) Anterior Compartment of the Leg Flashcards
The anterior compartment of the leg
Enclosed by dense fascia, bone, IO membrane
susceptible to compartment syndrome
Blood supply to Anterior compartment of the leg
Anterior tibial artery
terminal branch of popliteal
Innervation to muscle of Anterior compartment of the leg
Deep fibular nerve (L4, L5, S1)
Tendons of muscles of anterior compartment of the leg
Surrounded by synovial sheath as they pass ankle
visible/palpable over ankle with contraction
Function of muscles of Anterior compartment of the leg
Ankle dorsiflexion
Extend digits
Tibialis Anterior characteristics
Largest anterior muscle
Visible and palpable proximally
Tendon palpable and visible as it crosses ankle joint
Origin of Tibialis Anterior
Lateral tibial condyle
Upper 2/3 lateral surface of tibial shaft
IO membrane
Crural fascia
Insertion of Tibialis Anterior
Medial plantar surfaces of medial cuneiform
Medial plantar surface of 1st met base (metatarsal tubercle)
Function of Tibialis Anterior
Dorsiflex/Invert foot
Supinate subtalar joint
Origin of Extensor digitorum longus
Lateral tibial condyle
Superior 3/4 fibular shaft
IP membrane
Crural fascia
Insertion of Extensor digitorum longus
Tendons divide into 4 slips (digits 2-5)
Insert on dorsal surface of bases of 2nd-5th middle and distal phalanges
Insertion of EDL contributes to
Extensor expansion over digits (2-5)
Function of Extensor Digitorum Longus
Digit extension: dorsiflexion (prox/distal IP and MTP joints)
Helps with dorsiflexion/eversion (subtalar pronation)
Extensor hallucis longus characteristics
DEEP to TA and EDL (superficial at distal leg/ankle)
Tendon BETWEEN TA and EDL and ankle joint
Origin of Extensor Hallucis Longus
Middle 1/3 of anteromedial aspect of middle fibular shaft and IO membrane
Origin more distal than TA and EDL
Insertion of Extensor Hallucis Longus
Dorsal aspect of base of distal phalanx of 1st digit
Function of Extensor Hallucis Logus
Extension (dorsiflexion) of 1st digit (hallux)
Origin of Extensor hallucis capsularis
Medial aspect of EHL tendon or muscle (sometimes TA)
Insertion of Extensor hallucis longus
Dorsomedial aspect of 1st MPJ capsule
Function of Extensor hallucis capsularis
Tension capsules during extension preventing capsular impingement
Fibularis (peroneus) tertius
May be absent
Passes anterior to lateral malleolus
Origin of fibularis (peroneus) tertius
Inferior 1/4 of medial fibular shaft
IO membrane
(may also originate from EDL muscle)
Insertion of fibularis (peroneus) tertius
Dorsal aspect of base and shaft of 5th metatarsal
sometimes base of 4th metatarsal
Function of fibularis (peroneus) tertius
Dorsiflexion/Eversion of foot
Subtalar pronation
Tibialis Anterior Synovial Sheath path
Begins: prox to superior extensor retinaculum (transverse crural ligament)
Ends: between oblique bands of inferior extensor retinaculum (cruciate crural ligament)
Tibialis anterior synovial sheath characteristics
Begins/ends most proximally
Within superior extensor retinaculum on oblique supermedial band of inferior extensor retinaculum
Extensor hallucis longus synovial sheath path
Begins: immediately proximal to oblique superomedial band of inferior extensor retinaculum (medial malleolus level)
Ends: 1st metatarsal base
Extensor hallucis longus synovial sheath characteristics
Within inferior extensor retinaculum
Ends most distally
Extensor digitorum Longus/Fibular tertius path
Beings: proximal to oblique superomedial band of inferior extensor retinaculum
Ends: level of 5th metatarsal base
Extensor digitorum Longus/Fibular tertius characteristics
Both share synovial sheath
(4 EDL tendons | 1 FT tendon)
Within inferior extensor retinaculum
Extensor Retinacula
Holds extensor tendons in place over extensor surface of ankle joint
Superior extensor retinaculum
AKA: Transverse crural ligament
Thickening of crural fascia
Attaches to anterior aspect of tibia and fibula distal shafts
Superior extensor retinaculum content
TA Rest (pass deep)
Inferior extensor retinaculum
AKA: Cruciate crural ligament
Thickening of crural fascia and deep fascia over foot dorsum
Inferior extensor retinaculum structure
Y shaped band (stem and 2 oblique medial bands)
Stem of the Y shaped band
Lateral
Frondiform ligament
Lateral attachment of Inferior extensor retinaculum
Frondiform ligament
Lateral talar neck and superior calcaneus within sinus tarsi
Medial attachment of Inferior extensor retinaculum
Anterior aspect of distal medial malleolus (olblique superomedial band)
Plantar aspect of medial cuneiform/navicular (oblique inferomedial band)
Inferior extensor retinaculum is continuous with
Inferior fibular retinaculum
Inferior extensor retinaculum content
Tendons of anterior compartment muscles
pass within
Entry of Anterior Tibial artery into Anterior compartment
Through proximal opening of IO membrane into Anterior compartment
Path of Anterior Tibial Artery
Located between TA and ED (prox leg)
Between TA and EHL (distal leg)
EHL tendon crosses over artery at distal ankle
Anterior tibial becomes
Dorsalis pedis after ankle
between EDL and EHL
Small anterior tibial can be replaced by
Perf branches from posterior tibial and perforating fibular artery
Anterior Tibial artery branches off popliteal
Near inferior border of popliteus. Through superior opening of IO membrane and into Anterior compartment
Branches of Anterior Tibial artery
Post Tib Recurrent Ant Tib Recurrent Musc branches Ant Med Malleolar artery Ant Lat Malleolar artery Dorsalis pedis (continuation of Ant Tibial)
Venous flow in Anterior Compartment
Anterior Tib + Post Tib to Pop Vein to Fem Vein
Deep fibular nerve root level
(L4-S1)
Branches from common fibular in lateral compartment
Path of Deep Fibular nerve
Enters through anterior IM septum into anterior compartment
Descends along anterior surface of IO membrane (with Ant Tib artery)
Deep Fibular nerve orientation
Leg and ankle: Lateral to artery
Enters dorsum of foot deep to extensor retinacula
Deep fibular nerve supplies
Anterior compartment and foot dorsum muscles
Branches of Deep fibular nerve
Lateral terminal branch (follows lateral tarsal or arcuate arteries)
Medial terminal branch (continuation of deep fibular)
Lateral terminal branch of deep fibular nerve
innervates EHB and EDB
Joints of lateral foot
Medial terminal branch of deep fibular nerve
Communicates with superficial fibular nerve
comm branch of superficial fibular nerve
Medial terminal branch of deep fibular nerve follows
Dorsalis pedis and 1st dorsal metatarsal arteries
Medial terminal branch of deep fibular nerve innervates
1st dorsal interossei muscle
Joints of medial foot
Branches of medial terminal branch
Proper dorsal digital nerve 2
Proper dorsal digital nerve 3
Proper dorsal digital nerves 2-3 innervate
Cutaneous to dorsolateral hallux (2)
Cutaneous to dorsomedial 2nd toe (3)
Toe tips are innervated by
Nerves from plantar aspect of the foot