S2 - Lower Limb (leg) Flashcards
common peroneal (fibular) nerve:
- what roots is it made up of
- motor innervation
- sensory innervation
- where does it run anatomically
- L4-S2
- motor: common branch supplies short head of biceps femoris, superficial branch supplies lateral compartment, deep branch supplies anterior compartment
- sensory: lateral aspect of lower leg, dorsal aspect of foot
- runs laterally down the posterior leg, splits into deep and superficial branches (superficial is @ risk of damage inferior to knee joint)
- deep branch runs over dorsum of foot and branches into medial and lateral cutaneous nerves of the foot
tibial nerve:
- what roots is it made up of
- motor innervation
- sensory innervation
- where does it run anatomically
- roots: L4-S3
- motor: hamstrings (except short head of biceps femoris), hamstring part of adductor magnus and posterior compartment of leg
- sensory: posterolateral lower leg, plantar surface of the heel
- runs posteriorly down the middle of the leg, goes posterior to medial malleolus
- emerges on plantar surface of foot and divides into medial and lateral plantar nerve
where does the dorsals pedis a. run?
- in between the 1st and 2nd toes
superficial veins of the leg
- great/long saphenous vein: starts @ dorsum of foot, over medial malleolus, runs posterior to knee, emerges into medial thigh and drains into femoral v. in femoral triangle
- small/short saphenous vein: starts on lateral foot, runs up posterior leg, drains into popliteal vein in popliteal fossa
describe the deep veins of the leg + thigh
- basically same as arteries
describe the arterial supply of the leg
- popliteal artery: emerges down from popliteal fossa and divides into anterior tibial artery
- anterior tibial artery runs thru proximal aperture in interosseous membrane
- posterior division divides further into the peroneal (anterior) and posterior tibial artery
- posterior tibial artery goes down and passes medially into the foot > divides into lateral and medial plantar arteries > deep plantar arch
- peroneal artery runs along fibula and ends laterally at the foot
- anterior tibial artery runs along interosseous membrane and turns into dorsalis pedis (b/n 1st and 2nd toes)
what do the tibial and fibular arteries supply?
- anterior tibial: anterior compartment of lower leg + dorsal aspect of foot
- posterior tibial: posterior compartment of lower leg + plantar aspect of foot
- fibular: lateral compartment of lower leg
difference between medial and lateral condyles of the tibia
- medial: larger, raised and lifted up (complete fossa)
- lateral: smaller, smooth, sloped away on the posterior side
what are A, B, C, D?
- A = lateral epicondyle
- B = lateral condyle
- C = adductor tubercle
- D = medial epicondyle
what are E, F, G, H, I?
- E = medial condyle
- F = intercondylar line
- G = medial supracondylar line
- H = lateral supracondylar line
- I = intercondylar fossa
what are A, B, C, D?
- A = tibial tuberosity
- B = lateral condyle
- C = intercondylar eminences (lateral + medial)
- D = medial condyle
structure and function of the knee menisci (general)
- S = wedge-shaped fibrocartilage attached to the tibial intercondylar eminence, inner surface is avascular, outer surface is vascular
- F = deepens articular space, disperses force and synovial fluid
how do the medial and lateral menisci differ?
- ends of the medial meniscus are attached further apart (larger), whereas lateral = closer together (smaller)
- medial = attached to joint capsule (less mobile, more prone to injury) whereas lateral = free from joint capsule (more mobile and LESS prone to injury)
4 ligaments of the knee joint
- ACL
- PCL
- MCL
- LCL
where do the ACL and PCL attach?
- ACL: goes from lateral aspect of lateral condyle (femur) to medial portion of intercondylar eminence (tibia - same place as medial meniscus attachment)
- PCL: goes from lateral aspect of medial condyle (femur) to lateral portion of intercondylar eminence (tibia)
when can the patella track laterally?
- doing lots of repetitive action where the knee is not fully extended e.g. running/cycling
- lateral quads get stronger than medial > patella is pulled laterally
- bones rub together where they shouldn’t
- wear away meniscus and joint
function of ACL and what movement will damage it?
- prevents posterior displacement of the femur on a fixed tibia
- prevents anterior displacement of the tibia on a fixed femur
- (damaged in hyperextension)
function of PCL and what movement will damage it?
- prevents anterior displacement of the femur on a fixed tibia
- prevents posterior displacement of the tibia on a fixed femur
- (damaged w/ hyperflexion)
MCL and LCL differences
- when are they most tight?
- MCL (tibial): attaches to medial meniscus
- LCL (fibular): not attached to lateral meniscus
- both are more taut in extension to prevent valgus and varus movement
where do the MCL and LCL attach?
- MCL: medial epicondyle of femur > tibia
- LCL: lateral epicondyle of femur > styloid process of head of fibula
what are the retinacula of the knee?
- medial + lateral
- fibrous tissue that provides stability
unhappy triad
- a blow to the lateral side of the knee (> valgus = bow-legged) can damage the MCL, medial meniscus and ACL
- b/c MCL attaches to medial meniscus and ACL also shares an attachment point w/ the medial meniscus on the joint capsule
impact of tearing ACL/PCL on synovial membrane
- (esp. ACL)
- likely to damage synovial membrane b/c it runs right around the ligaments
- leads to significant swelling
4 bursae and fat pad of the knee
- suprapatellar (quadriceps) bursa - under quadriceps tendon
- prepatellar (anterior to patella)
- infrapatellar (superficial + deep) - anterior and posterior to patellar ligament
- semimembranosus - between semimembranosus and gastroc (medial)
- fat pad is posterior to patellar tendon
describe the articular surfaces of the patella
- lateral facet is larger than the medial facet
describe the boundaries of the popliteal fossa (diamond shape)
- superomedial: semimembranosus + semitendinosus
- inferomedial: medial head of gastroc
- superolateral: biceps femoris
- inferolareral: lateral head of gastroc + plantaris
contents of the popliteal fossa
- popliteal artery (most medial)
- popliteal vein (saphenous vein drains into this)
- sciatic nerve: divides @ the apex of the fossa into tibial n. and common peroneal n. (most lateral)
compartments of the lower leg and what are they separated by?
- anterior
- superficial + deep posterior (separated by transverse intermuscular septum)
- lateral (bordered by the anterior and posterior crural septa)
muscles in the posterior superficial compartment and what movement are they responsible for?
- also what nerve innervates them?
- gastroc
- soleus
- plantaris
- plantar flexion
- tibial nerve
what is this muscle?
- what is its origin and insertion?
- innervation?
- movement?
- gastrocnemius (medial and lateral head) - posterior superficial
- origin: medial and lateral condyles (femur)
- insertion: calcaneal tendon
- innervation: tibial nerve
- movement: plantar flexion and knee flexion
what is this muscle?
- what is its origin and insertion?
- innervation?
- movement?
- soleus (deep to gastroc) - multipennate (anti-gravity) - posterior superficial
- origin: back of tibia and fibula
- insertion: calcaneal tendon
- innervation: tibial nerve
- movement: plantar flexion
what is this muscle?
- what is its origin and insertion?
- innervation?
- movement?
- plantaris - posterior superficial
- origin: lateral epicondyle of femur
- insertion: calcaneal tendon
- innervation: tibial nerve
- movement: weak plantar flexion
what muscles are in the deep posterior compartment and what nerve innervates them?
- Tom, Dick and Harry (+pop)
- tibialis posterior (deepest posterior muscle)
- flexor digitorum longus
- flexor hallucis longus
- popliteus
- tibial nerve
what is this muscle?
- what is its origin and insertion?
- innervation?
- movement?
- tibialis posterior - posterior deep
- origin: interosseous membrane
- insertion: goes behind medial malleolus, fans out underneath the foot
- innervation: tibial nerve
- movement: plantar flexion, inversion
what is this muscle?
- what is its origin and insertion?
- innervation?
- function?
- popliteus - posterior deep
- origin:
- insertion: half lateral meniscus, half lateral condyle of femur
- innervation: tibial nerve
- function: unlock the knee during walking (help it come out of extension)