Lecture 13: Posterior thigh and knee Flashcards
Describe msucles of posterior thigh
Hamstrings = 3 msucles, 4 heads
= biceps femoris, semitendinosus, semimembranosus
Name common proximal attachment of hamstrings
Ischial tuberosity
Except short short of biceps femoris
Name functions fo hamstrings
Hip extension - passse post at high joint
Knee flexion
Exception = short head biceps femoris - doesn’t contribute to hip extension
Descrivbe biceps femoris
2 heads -
Long and short
Separate origins, common insertion
Describe long head biceps femoris attachments
Ischial tuberosity
To head of fibula
Describe short head biceps femoris attachments
Posterior femur - nest to linea aspera
To head of fibula
Describe biceps femoris tendon
Tendon
Need to cut long head part to see short head part
SemiTendinosus attachments
Ischial tuberosity to
Anteromedial tibia - pes anserinus
Semimembranosus attachments
Ischial tuberosity to
Posteromedial tibia
(Flatter tendon)
What do hamstrings contribute to
Superior border of popliteal fossa - splitting of hamstring msucles
Medial = semitendinosus and membrnaosus
Lateral = biceps femoris
Pes anserinus
Sartorius
Gracilis
Semi tendinosus
Innervation of hamstrings generally
Sciatic nerve and its branches - l4-s3
Innervation of biceps femoris short head
Common fibular branch sciatic
Innervation of biceps femoris long head
Tibial branch sciatic
Innervation of semitendinosus
Tibial branch sciatic
Innervation of semi membranosus
Tibial branch sciatic
Sensory to posterior thigh
Not sciatic
Sensory = posterior femoral cutaneous
Blood supply to posterior thigh
Via perforating arteries of deep formal artery
Openings in adductor Magnus allow perforating arteries to travel from ant to posterior
Blood supply to knee and below
Femoral artery
What makes up knee joint
Patella
Femur
Tibia
Large, not very stable
Name the 3 articulations of knee joint
Tibial plateau = medial femoral with medial tibial condyle, lateral femoral with lateral tibial condyle = 2
Patella with patellar groove of femur - femoral trochlea = 1
Which bones do not contact each other in knee joint
Patella and tibial
Separated by infrapatellar fat pad
patella only in contact with femur
Describe patellar ligament
Continuation of quadriceps tendon
How patella connected to tibial tuberosity
Describe infra patellar fat pad
Behind patella ligament = cushions
Describe supra patellar pouch
Contraction of synovI’ll capsule onto anterior side
Accommodate range of motion
Particularly large on anterior side bc gets most stretched in flexion
What is purpose of suprapatellar pouch - explains more
Rom = 120-150 degrees
Capacious - roomy synovial cavity to accommodate large range fo motion - due to suprapetellar pouch - superior continuation of synovial cavity
Describe clinical correlate knee joint
Patellofemoral pain syndrome
Runners knee -misalignment - improper tracking of patella in patellar groove
Lateral shift = patella rubs against another part of articular cartilage = can cause erosion and degeneration of trochlea and patella
What are causes of patellofemoral pain syndrome
Variable
Can include weak vastus medialis or lateralis or tight it band= lead to lateral pull on patella in groove
If one weaker = pulls too much
What are treatments of patellofemoral pain syndrome
Strengthen quadriceps - vastus medialis to restore proper tracking of petals in the patellar groove or braces to physically prevent lateral tracking
Why do we need to reinforce knee joint
Can do some axial rot but need to limit it
Also to limit flex/ext
KNEE SHOULD NEVER ADD/ABDUCT
Name ligaments that reinforce knee joint
Collateral ligaments
Cruciate ligaments
Name extra capsular ligaments
Medial tibial collateral ligament - mcl
Lateral fibular collateral ligament - lcl
Describe attachments of medial collateral ligament
Medial femoral epicondyle,
Proximal tibia
Medial meniscus
Describe features of medial collateral ligament
Flat band
Blended with joint capsule wall
Firm attachment to medial meniscus
Most commonly injured - if excessive axial rot
Describe attachments of lateral collateral ligament
Lateral femoral epicondyle
Head of fibula
Describe features of lateral collateral ligament
Round - cord like
Completely outside joint capsule
Smaller - distal femur to head fibula
What are functions of collateral ligaments
Stabilize knee
Limit excessive flex/ext and axial ro
Prevent exceeding rom
Name intra capsular ligaments
Anterior Cruciate ligament
posterior Cruciate ligament
- cross each other
Still outside synovial cavity/membrane tho
Describe anterior Cruciate ligament
Backwards, upwards, lateral
Medial on tibia to lateral femoral condyle femur
Describe posterior Cruciate ligament
Forwards, upwards, medial
Describe functions of anterior Cruciate ligament
Stabilize knee
Limit anterior translation of tibia relative to femur
Describe functions of posterior Cruciate ligament
Limit posterior translation of tibia relative to femur
Describe functions of both anterior and posterior Cruciate ligaments
Limit axial rotation
What does acl limit
Anterior displacement of tibia on fixed femur
What does pcl limit
Posterior displacement of tibia on fixed femur
What do both acl and pcl limit
Axial rotation of knee
Describe rupture of Cruciate ligaments
Sudden medial rotation of femur relative to fixed tibia
- especially acl
Whenever student rotation of femur relative to a fixed tibia - even when against ground
Like skiing, or soccer or hockey
Describe drawer tests - gen
Asses motion of tibia relative to femur
Tested with flexed leg so both ligaments are lax
Describe drawer tests - anterior drawer sign
If can pull tibial more on one side towards anterior = acl ruptured
Describe drawer tests - posterior drawer sign
If push tibia back more on one side = pcl ruptured
What are menisci
Fibrocartilaginous discs - wedge shaped in coronal section = provide cushioning for knee and increase joint congruence of femoral and tibial condylar surfaces = fills in space
Function of menisci
Not good congruence between femoral condyels so menisci = provide more surface area for bones = stabilize by distributing stress for stability
Where are menisci
Inside both fibrous capsule and synovial cavity
Describe medial meniscus
Attached to mcl
Relative immobile
Crescent shaped
Describe lateral meniscus
Fairly mobile
Circular in shape - almost complete O
Not anchored
Sits on lateral condyle femur
Describe capsular relations of collateral ligaments
Outside fibrous capsule = lcl
Blended with fibrous capsule = mcl
Describe capsular relations of cruciate ligaments
Inside fibrous capsule but outside synovial cavity
Describe capsular relations of menisci
Inside synovial cavity
How are acl and pcl not in synovial cavity but inside fibrous capsule???
Synovial membrane draped over acl = rests on it
Describe screw home mechanism
In full knee extension = tibia and femur rotate axially on each other = locking knee into a more stable position
Describe screw home mechanism = when tibia fixed
Like while standing
Femur rotates medially to lock at full extension = strengthens knee joint
Laterally to unlock
Describe screw home mechanism = when femur fixed
Like when sitting or leg extension machine
Tibia rotates laterally to lock
Medically to unlock
Describe popliteus muscle attachments
From lateral femoral condyle - deep to lcl
To posterior superior tibia, medial half
Describe popliteus muscle function
Helps to unlock knee - lat rotation
And initiate flexion
What is popliteal fossa
Diamond shaped area posterior to knee joint
Popliteal fossa borders
Bordered by hamstrings superiorly = semitendinosus and membranosus medially and biceps femoris laterally
Gastrocnemius heads inferiorly
What is in popliteal fossa
Many nerves and vascular structure s
Also many lymph nodes here
Describe nerves in popliteal fossa
Sciatic = ends near superior border of popliteal fossa
Branches = tibial continues down leg and then common fibular goes towards outside leg
Medial and lateral aural cutaneous nerves = sensory for surface
Descrive msucles of popliteal fossa
A above = semis and biceps femoris quadriceps
Below = medial and lateral heads of gastrocnemius = knee flexor and akle plantar flexor
What vascular contents pass through popliteal fossa
Continuation femoral artery and veins
= popliteal artery and vein
Lesser sapphenous vein - lateral dorsal venous arch, drains superficially, drains into femoral vein
Describe what happens when femoral artery and vein passs through adductor hiatus
Becomes popliteal Artery and vein
What supplies knee
Popliteal arter via genicular anastomosis
Lateral and medial branches popliteal artery above and below
Genicular arteries to knee, and anastomose = patellar network
Also supplies synovial capsule
How ro remember direction of Cruciate Ligaments
FUM - forwards, upwards, medial = pcl
BUL - backwards, upwards, lateral = acl
