Leg Lecture Content
What is unique about the plantaris?
- can be absent - easily mistaken for nerve due to long slender tendon - can rupture during activities leading to painful pop - can be removed for grafting due to its minor functional role
What are the characteristics and function of the knee menisci?
- crescentic plates of fibrocartilage that play role in shock absorption - thicker at external margins (wedge shaped) Medial - C-shaped - less mobile on tibial plateau Lateral - circular - more mobile - joins with posterior meniscofemoral ligament
What are the articular ligaments of the knee and their function?
- cross obliquely within joint capsule but outside synovial cavity - portion tense in every position - maintain contact of the femoral and tibial articular surfaces during flexion - medial winds together, lateral winds apart ACL - weaker - limits posterior rolling during flexion - prevents posterior displacement of femur during hyperextension - poor blood supply PCL - limits anterior rolling of femur during extension - prevents anterior femur displacement during flexion - prevents hyperflexion - main stabilizer of femur during weight-bearing flexion
What are the symptoms and possible consequences of a popliteal aneurysm?
- edema, pain, palpable pulsations, abnormal artery sounds, hemorrhage - stretch or compress tibial nerve due to being more deep - loss of leg and foot without early recognition and action
What is the functional advantage of the patella?
- helps withstand the compression of quadriceps tendon during kneeling or friction during flexion/extension - leverage for the quadriceps to tibia for easier knee extension
What is the origin of the sural nerve and what does it supply?
- medial sural from tibial + lateral sural from common fibular - supplies lateral side of leg and ankle
What are the actions, innervations, and blood supply of the posterior leg?
- posterior tibial artery Gastrocnemius - plantarflexion and knee flexion - tibial nerve - most effective with knee extension Soleus - plantarflexion (no knee action) - tibial nerve Plantaris - weak plantarflexion - tibial nerve Poplitus - tibial nerve - weak knee flexion Tibialis posterior - tibial nerve - ankle plantarflexion, foot inversion - support medial longitudinal arch Flexor digitorum longus - tibial nerve - digit flexion, ankle plantarflexion Flexor hallucis longus - tibial nerve - hallux flexion, weak ankle plantarflexion
What are the actions, innervations, and blood supply of the lateral leg?
- superficial fibular (from common fibular) - foot eversion and plantarflexion - perforating branches of the anterior tibial and fibular artery Fibularis longus - more superficial and superior - medial insertion allows it to steady leg on foot when standing Fibularis brevis - insertion onto 5th digit can vary
What is unique about the popliteus?
- unlocks knee from full extension - inferior border of popliteal fossa
What are the collateral ligaments of the knee and their function?
ALL contribute to stability while standing and limit rotation Fibular collateral - lateral - popliteus tendon passes under Tibial collateral - medial - weaker than FCL so commonly torn - attached to medial meniscus Oblique popliteal - posterior reinforcement Arcuate popliteal - strengthens posterolateral joint capsule
What compartment of the leg is most susceptible to compartment syndroms?
Anterior due being relatively small and confined
What are the three types of tibial fractures and their characteristics?
Compound - direct trauma - damage to nutrient canal predisposes patient to nonunion of the bone fragments Transverse (stress) - inferior third - common in unconditioned hikers Diagonal - severe torsion affecting fibula as well - limb shortening due to overriding fractured ends "Boot-top" - high speed forward fall
What are the borders and contents of the popliteal fossa?
Superolateral = biceps femoris Superomedial = semimembranosus Inferior = gastrocnemius heads Contents - small saphenous termination - popliteal artery (deepest) - popliteal vein - sciatic -> tibial + common fibular - posterior cutaneous nerve of thigh
Where is the suprapatellar bursa?
above patella between tendon of quadriceps and femur
What is the significance of the posterior gap in the knee joint capsule?
allows the tendon of the poplitus to pass out of the joint capsule and attache to the tibia
What are the borders that divide the leg's anterior compartment?
anterior intermuscular septa, interosseous membrane, tibia
What are the actions, innervations, and blood supply to the anterior leg?
blood supply from anterior tibial artery Tibialis anterior - STRONGEST dorsiflexion - deep fibular nerve Extensor digitorum longus - digit extension and ankle dorsiflexion - deep fibular nerve - most lateral Extensor hallucis longus - hallux extension and ankle dorsiflexion - deep fibular nerve Fibularis tertius - ankle dorsiflexion - deep fibular nerve - part of EDL but not always present
What is the most powerful tendon in the body?
calcaneal tendon
What are the complications of compartmental infections in the leg?
closed space of compartments due to thick deep fascia allow build up of pressure with infection suppuration (pus formation) -> fasciotomy may be necessary to relieve pressure and debride pockets of infection
What ligaments are attached to the menisci of the knee?
coronary ligaments - between menisci transverse ligaments - joins anterior edges to each together during knee movements
A lesion to what nerve results in a footdrop?
deep fibular or common fibular more proximal due to lack of foot dorsiflexion
What is the articularis genu location and function?
deep to vastus intermedius attaching to synovial membrane to retract bursa during extension of knee
What is the flexor retinaculum and how is it formed?
dense band of tissue from the transverse intermuscular septum on medial ankle that forms the tarsel tunnel
What connects the shafts of the tibia and fibula?
dense interosseus membrane of oblique fibers
Where is the common location for fibular fractures?
distal end near lateral malleolus often associated with fracture dislocation of the ankle joint (combined with tibial fractures) - common in soccer and basketball players - disruption to muscle attachment
How is the flexor digitorum longus tested clinically?
distal phalanges of digits 2-5 are flexed against resistance and tendons can be palpates if acting normal
Branches from which nerves supply the knee joint?
femoral tibial common fibular
What movements are allowed by the knee joint?
flexion, extension, gliding/rolling about vertical axis -> impaired with hyperextension
What two tendons cross each other in the sole of the foot?
flexor hallucis longus flexor digitorum longus
How is the tibialis posterior tested clinically?
foot is inverted against resistance with the foot in slight plantarflexion and normal tendon can be seen and palpated
How is the triceps surae tested clinically?
foot is plantarflexed against resistance and can be observed/palpated if normal
What muscles make up the triceps surae?
gastrocnemius and soleus, provides 93% of plantarflexion force
How is the flexor hallucis longus tested clinically?
hallux if flexed against resistance and tendon can be seen and palpated if normal on plantar aspect of toe
How is the extensor hallucis longus clinically tested?
hallux is dorsiflexed against resistance and tendon can be seen and palpated if acting normally
Why is it important that the soleus pulls posteriorly on the leg bones?
important for standing because line of gravity passes anterior to the bony axis -> anti-gravity muscle for standing and strolling -> dorsiflexor antagonist
What is bursitis and where does it occur in the knee?
inflammation of bursae sacks usually from friction but also compressive forces - subcutaneous infrapatellar busitis from friction between skin and tibial tuberosity causing edema over proximal end - deep infrapatellar bursitis from friction between patellar tendons and posterior structures cuasing edem between ligament and tibia -> chronic inflammation forms swelling over knee
What are the borders of the lateral leg compartment?
lateral fibula anterior intermuscular septa posterior intermuscular septa
How is the extensor digitorum longest clinically tested?
lateral four toes are dorsiflexed against resistance and tendons can be palpated if acting normal
What is the significance of the knee joint being able to passively lock into one position? What muscle unlocks the knee?
lower limb becomes a solid column during full extension with planted foot -> unlocked by popliteus
What are retinacula and their significance in the knee joint?
maintain alignment of the patella relative to the patellar articular surface of the femur
What is a synovial membrane?
membrane that surrounds the inside of the joint capsule
Why is compartment syndrome more serious in the posterior leg?
nerve and blood vessels supplying compartment passes through the deep subcompartment so swelling can lead to necrosis and paralysis
What are the genicular branches and their significance?
network of vessels providing collateral circulation that can maintain blood supply to leg/knee during full knee flexion
What is the path of blood supply in the anterior leg?
popliteal artery anterior tibial artery dorsalis pedis artery
What is the path of blood supply in the posterior leg?
posterior tibial artery fibular artery medial plantar lateral plantar
What muscle realigns the pull of the flexor digitorum longus?
quadratus plantae attaches to muscle where tendon splits into four to insert onto digits
What is the most common site for a tibial fracture and why?
shaft at the junction of its middle and inferior thirds where tibia is most narrow with poorest blood supply
Why can't the deep posterior leg muscles lift the body's weight after calcaneal tendon rupture?
they only produce about 7% of the total force of plantar flexion
What extensor and flexor work synergistically to invert the foot?
tibialis anterior and posterior
What are the borders that create the posterior leg compartment?
transverse intermuscular septum
