Clinical Abatomy Of The Lower Limb 2 Flashcards
Describe the knee joint
The knee joint is the largest synovial joint in the body
Type: hinge
-articulation between the femoral condyles and superior aspect of tibial condyles
-articulation between the patella and the femur
Describe the two menisci of the knee joint
Fibrocartilaginous C-shaped cartilages
- menisci increase the congruency between the tibial and femoral
- attached medially to the intercondylar region of the tibia
- medial meniscus: attached around its margin to the capsule of the joint and to the tibial collateral ligament
Lateral meniscus: unattached to the capsule as tendon of the popliteus muscle passes between them
What connects the two menisci of the knee?
Transverse ligament of the knee connects the anteriorly
What is the function of the patellar ligament?
Pateliar ligament: the continuation of the quadriceps femoris tendon inferior to the patella
Contrast the tibial(medial) collateral ligament and the fibula (lateral) collateral ligament
Tibial (medial) collateral ligament- medial femoral Condyle to the medial aspect of tibia (deep fibers are attached to the medial meniscus)
Fibulae (lateral) collateral ligament-lateral femoral condyle to the fibular head
What is the function of the anterior Cruciate ligament?
-attaches on the anterior part of the intercondylar area of the tibia and ascends posteriorly to attach at the back of the lateral wall of the intercondylar fossa of the femur
- prevents anterior displacement of the tibia relative to the femur
- prevents posterior displacement of the femur
What is the function of the posterior Cruciate ligament?
-attaches to the posterior aspect of the intercondylar area of the tibia and ascends anteriorly to attach to the medial wall of the intercondylar fossa of the femur
- Restricts posterior displacement of the tibia relative to the femur
- restricts anterior displacement of the femur
Explain the locking mechanism
When standing, the knee joint is locked into position, thereby reducing the amount of muscle work needed to maintain the standing position.
Locking mechanism is achieved by:
-The change in the shape and size of the femoral surfaces that articulate with the tibia dueling extension. The joint surfaces become larger and more stable in extension.
-medial rotation of the femur on the tibia during extension that tightens all the associated ligaments
The popliteus muscle unlocks the knee by initiating lateral rotation of the femur on the tibia
What causes genu varus & valgus ?
Changes in the distribution of weight to the tibia can cause increase or decrease in the space between the femur and patellar
Genu varus- knees bow outward, giving bow legged appearance
Genu valgus- inward bending at the knees
What is the unhappy triad?
Excessive force to the lateral side of the knee (valgas pressure):
- medial collateral (most common)
- anterior cruciate
- medial memiscus/lateral meniscus
Describe the knee bursae
Anteriorly, the synovial membrane is separated from the patellar ligament by an infrapatellar fat pad
Suprapatellar bursa: continuous with the Articular cavity superiorly between the distal end of the shaft of the femur and the quadriceps femoris muscle and tendon
Aside from knee bursae, what other bursae exist that associate with the knee, but not normally communicating with the artcular cavity ?
These include:
- subcutaneous prepatellar bursa (housemaid knee-pratellar bursitis)
- deep and infrapatellar bursa
- subcutaneous infrapatellar bursa (clergyman’s knee)
Summarize blood supply to the knee
5 genicular arteries from the popliteal artery
-superior medial genicular
- superior lateral genicular
- inferior medial genicular
- inferior lateral genicular
- middle genicular
Recurrent branch of anterior tibial artery
2 descending genicular arteries
- one from femoral artery
- one from the lateral circumflex
Explain the leg compartments/divisions
The leg is divided into anterior, posterior and lateral compartments by:
- interosseous membrane
- fascia cruris (deep fascia)
- two inter muscular septa (fibula to deep fascia)
- direct attachment of the deep fascia to the periosteum of the tibia
What are the compartments of the leg?
Lateral compartment-
-superficial fibular nerve= eversion of foot
- Anterior compartment= extensor compartment, deep fibular nerve
- dorsiflexion (extension) of foot
- inversion
- Posterior compartment= flexor compartment, tibial nerve
- planterflexion (flexion) of the foot
- inversion
What are the muscles of the posterior compartment of the lower limb?
- gastrocnemius
- soleus
- plantaris
- tibialis posterior
- flexor digitorum longus
- flexor hallucis longus
- popliteus
What are the posterior compartment of the motor and sensory innervation of the lower limb?
Tibial nerve
What is the opening(canal) of the posterior compartment of the lower limb
Medial tarsal tunnel
What is the blood supply of the posterior compartment of the lower limb?
Posterior tibial artery
What are the general functions of the posterior compartment of the lower limb?
Planter flexion of the ankle joint, tibialis posterior also inverts, flexion of digits
What is the innervation and function of the gastrocnemius?
Tibial nerve
-plantar flexes ankle joint/foot and flexes the knee/leg
What is the function and innervation of the plantaris(vestigial)?
Tibial nerve
-plantar flexes ankle joint/foot and flexes the knee/leg
What is the function and innervation of soleus?
Tibial nerve
-plantar flexes ankle joint/foot
What is the triceps surae?
The soleus and gastrocnemius join to form the triceps surae and insert on the calcaneus via the calcaneal tendon. The triceps surae propels the body forward when walking
What is the popliteal fossa ?
Diamond shaped space behind the knee joint
What forensic the upper margins of the popliteal fossa?
Upper margins:
-medially: semitendinous and semimembranous muscles
-laterally: biceps femoris muscle
What are the lower margins of the popliteal fossa?
- medially: medial head of the gastrocnemius muscle
- laterally: plantaris muscle and the lateral head of the gastrocnemius muscle
What for,s the floor of the popliteal fossa?
- capsule of the knee joint and adjacent surfaces of the femur and tibia
- more inferiorly, the popliteus
What are the contents of the popliteal foss?
Arranged from superficial to deep:
-tibial and common fibular nerves
- popliteal vein
- popliteal artery
Roof: covered by fascia and skin
-small saphenous vein
Posterior cutaneous nerve of the thigh
What is the innervation and function of the flexor digitorum longus?
Tibial nerve
Flexes lateral 4 toes
What is the innervation and function of the popliteus?
Tibial nerve
Unlocks the knee
What is the function and innervation of the tibialis posterior?
Tibial nerve
- plantar flexion & inversion of ankle joint/ foot
- support arch of foot
What is the innervation and function of the flexor hallucis longus?
Tibial nerve
Flexes the great toe
What are the muscles of the anterior compartment of the lower limb?
- tibialis anterior
- extensor digitorum longus
- extensor hallucis longus
- fibularis tertius
What are the motor and sensory innervation of the anterior compartment of the lower limb?
Deep fibular nerve
What is the blood supply of the anterior compartment of the lower limb?
Anterior tibial artery
What are the general functions of the anterior compartment of the lower limb?
-dorsifkexion of the ankle joint, tibialis anterior also inverts, extension of digits
What is the innervation and function of the extensor digitorum longus?
- deep fibular nerve
- dorsiflexion of ankle joint/foot
- extension of four lateral toes
What is the function and innervation of the tibialis anterior?
Deep fibular nerve
- dorsiflexion and inversion of ankle joint/foot
- support arch of foot
What is the innervation and function of the extensor hallucis Longus?
Deep fibular nerve
Dorsiflexion of ankle joint/foot
Extension of big toe
What is the function and innervation of the fibularis tertius?
Deep fibularis nerve
Dorsifkexion and eversion of ankle joint/foot
What muscles make up the dorsum of the foot?
Extensor hallucis brevis
Extensor digitorum brevis
What is the function and innervation of the extensor digitirum brevis ?
Deep fibular nerve
Extension of toes II-IV
What is the function and innervation of the extensor hallucis brevis?
Deep fibular nerve
-extension of MTPJ of big toe
What are the muscles of the lateral compartment of the lower limb?
Fibularis longus
Fibularis brevis
What are the sensory and motor innervation of the lateral compartment of the lower limb?
Superficial fibular nerve
What is the blood supply of the lateral compartment of the lower limb?
Fibular artery
What are the general functions of the lateral compartment of the lower limb?
Eversion of the ankle joint, supports the arch of the foot
What are the functions and innervation of the fibulaarus longus?
Superficial fibular nerve
- eversion of ankle joint/foot
- support arch of the foot
What are the functions and innervation of fibularis brevis?
Superficial fibular nerve
-eversion of ankle joint/foot
Summarize info on the arteries of the anterior and posterior compartment
Posterior tibial artery:
-originates from the popliteal artery in the popliteal fossa and enters the posterior compartment of the leg
-continues to the tarsal tunnel and splits into medial and lateral plantar arteries that supply the plantar surface of the foot
This gives the following branches:
- fibular
- circumflex fibular
Perforating arteries from the fibular artery supply the lateral compartment
What are the arteries of the anterior compartment of the lower limb?
Anterior tibial artery:
-originates from the popliteal artery
- passes forward into the anterior compartment of the leg through an aperture in the interosseous membrane
- It leaves the leg by passing anterior to the distal end of the tibia and ankle joint and continues onto the dorsal aspect of the foot as the dorsalis pedis artery
Describe the effects of tibial nerve injury
Severance of the tibial nerve affects the posterior compartment of the leg and the muscles in the plantar surface (sole) of the foot.
- Patients are unable to plantarflex the ankle joint. They also have decreased inversion of the ankle joint. All functions (except fir extension) of the intrinsic joints of the feet will be lost
- Loss of sensation on the posterior-lateral leg and the sole of the foot
Explain the effects of common fibula injury
Injury to the common fibular nerve affects lateral and anterior compartments of the leg and the muscles on the dorsum of the foot
-Foot drop is the result due to loss of dorsiflexion. There will also be decreased inversion of the foot. There will be loss of extension of the digits.
Lower limb becomes ‘too long’ so to compensate, the person will use a high stepping gait and/or swing out the leg
Loss of sensation of the inferior-anterior leg and dorsum of the foot
