Anterior and Lateral Leg Flashcards
- deep fascia of the leg that is continuous with fascia lata
- covers leg muscles
- part of proximal attachment of underlying muscles
- thickens distally to form extensor retinaculum (L., band or halter) which prevents bowstringing during dorsiflexion
crural (leg) fascia
What is the important of leg fascia in terms of blood flow?
- aids in muscle contraction that allows blood (via veins) to flow up the leg back to the heart
- with age: the fascia can loosen, leading to varacosities, spider veins, and edema
Crural Fascia
- anterior and lateral compartments separated by:
- anterior and deep posterior compartments separated by:
- lateral and superficial posterior compartments separated by:
- deep posterior and superficial posterior compartments separated by:
Crural Fascia
- anterior and lateral compartments separated by: anterior septum
- anterior and deep posterior compartments separated by: interosseous membrane
- lateral and superficial posterior compartments separated by: posterior septum
- deep posterior and superficial posterior compartments separated by: transverse septum
(deep (crural) fascia surrounds all of the compartments)
Where does the lateral compartment of the leg receive blood supply from?
from fibular arterial branches coming from deep posterior compartment
Where is the anterior compartment of the leg muscles located in terms of septum location?
What are the muscles of the anterior leg?
What is the primary function of these muscles?
- location is anterior to interosseous membrane
- muscles: tibialis anterior, extensor hallucis longus, extensor digitorum longus, fibularis tertius
- function: dorsiflexion, toe extension
Tibialis Anterior M.
- Origin:
- Insertion:
- Action:
- Innervation:
Tibialis Anterior M.
(long thick muscle on anterolateral surface of tibia)
- Origin: lateral tibial condyle and superolateral 1/2 of tibia
- Insertion: medial surface of 1st (medial) cuneiform and 1st metatarsal base
- Action: dorsiflexion and inversion of ankle
- Innervation: deep fibular N.
Extensor Digitorum Longus
- Origin:
- Insertion:
- Action:
- Innervation:
Extensor Digitorum Longus
- Origin: lateral tibial condyle, anterior fibular surface, interosseous membrane
- Insertion: each of the 4 tendons forms an extensor expansion over dorsum of lateral 4 proximal phalanges that divide into 2 lateral slips (distal phalanx) and 1 central slip (middle phalanx)
- Action: extends lateral 4 digits, dorsiflexion
- Innervation: deep fibular N.
Fibularis Tertius
- Origin:
- Insertion:
- Action:
- Innervation:
Fibularis Tertius
(fuse w/ digitorum longus proximally, does not attach to digit, variably present)
- Origin: anteroinferior fibular surface
- Insertion: dorsum of 5th metatarsal base
- Action: dorsiflexion, eversion
- Innervation: deep fibular N.
Extensor Hallucis Longus
- Origin:
- Insertion:
- Action:
- Innervation:
Extensor Hallucis Longus
(lateral to tibialis anterior)
- Origin: anteromedial fibular surface and interosseous membrane, medial to distal half of the proximal attachment of extensor digitorum longus
- Insertion: base of distal phalanx of hallus
- Action: extend hallux (big toe), dorsiflex ankle
- Innervation: deep fibular N.
What is the course of the deep fibular N.?
What structures does it innervate?
- course: one of the two terminal branches of the common fibular N.: begins between fibula and fibularis longus M., runs inferomedially w/ anterior tibial vessels between tibialis anterior and extensor hallucis longus, ends in medial and lateral terminal branches on dorsum of foot
- innervation: anterior compartment leg muscles, ankle joint and metacarpal phalangeal joints, dorsal intrinsic foot muscles, skin between 1st and 2nd digits
What artery supplies the blood to anterior leg compartment?
What is the course of this artery?
- anterior tibial A.
- arises from popliteal, begins near inferior border of popliteus M. (tibial tuberosity demarcates approx point of division of anterior and posterior tibial As.), passes anteriorly over interosseous membrane between EHL and TA Ms. w/ deep fibular N., ends at ankle between malleoli to become dorsal pedis A.
What are the muscles of the lateral compartment of the leg?
What nerve innervates this area?
- muscles: fibularis brevis and fibularis longus
- innervation: superficial fibular N.
What words may be used in place of fibularis/fibular?
(Just a reminder to watch out for these terms that are interchangeable and synonymous)
peroneus/peroneal
Fibularis Longus M.
- Origin:
- Insertion:
- Action:
- Innervation:
Fibularis Longus M.
(runs from fibular head to sole of foot, superficial to fibularis brevis)
- Origin: head and superolateral 2/3 of fibula
- Insertion: (passes inferoposteriorly to lateral malleolus) runs obliquely and distally across sole of foot to attach distally to first metatarsal and medial cuneiform bone
- Action: eversion and plantar flexion (prevents ankle sprains)
- Innervation: superficial fibular N.
Which foot bones have grooves for the fibularis longus to attach? (2)
What does this create with the fibularis longus?
- calcaneus B. (fibular trochlea) and cuboid B. (cuboid sulcus)
- helps create a sling that is a part of the transverse arch of foot, also helps support the longitudinal arch
Fibularis Brevis M.
- Origin:
- Insertion:
- Action:
- Innervation:
Fibularis Brevis M.
(deep to fibularis longus M.)
- Origin: inferolateral 2/3 of tibia
- Insertion: (descends posterior to lateral malleolus) attaches to dorsal surface of tuberosity on lateral side of 5th metatarsal
- Action: eversion and plantarflexion
- Innervation: superficial fibular N.
What is the most commonly injured lower extremity nerve?
What does this injury result in?
- common fibular N.: it winds superficially around fibular head, making it more susceptible to injury
- injury: paralysis of all anterior and lateral crural muscles, loss of dorsiflexion and eversion causes “foot drop”
- foot drop: difficult to achieve heel strike, patient has high stepping gait, waddling gait, or swing out gait, if leg swung strongly forward the foot strikes with a clap, loss of sensation along anterolateral leg and dorsum of foot
What artery supplies the lateral compartment of the leg?
- branches that pass anteriorly from the fibular A. (only compartment w/o a distinct arterial branch accompanying the compartment nerve)
(fibular A. is the largest branch of the posterior tibial A.)
