Anatomy - Lec.15

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Subject:

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Doctor:

Date:

Knee Joint & Popliteal fossa

Rashed Aljomard

Anatomy

System:

Sub-system:

Price:

25/51

15/24

25

Abdallah Masadeh

Thursady, 29/9/2011


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Knee joint

Lets go through the main idea of the knee joint , its the largest and the mostcomplicated joint .

The joint by definition is the point of meeting of two or more bones , synovial

joints is one of several types of joints , have synovial membranes and there is

synovial membrane in the knee joint , synovial membrane has ligaments and

knee joint has very special ligaments , and were going to focus on ligaments ofknee joint .

The knee joint is a modified hinge synovial joint , why not only hinge ? because

hinge like a typical hinge is the one like the elbow (like a door open and close )

and if you hold this door and try to do little gliding or any other movement it will

resist , it cant , knee can open and close and can do few other things thats whywe call it modified .what are the modifications ? gliding : moving a little pitanteriorly and posteriorly and laterally rolling rotation .


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Articulation of knee joint : i.e. what are the bones making the joints , this is

simple subject . two condyles of femur set on two condyles of tibia plus a

sesamoid bone which is patella and its within the quadriceps tendon and ithelps mechanically . the inner surface of the patella is part of the joint . so , two

femorotibial (two condyles of femur on two condyles of tibia) and onefemoropatellar (two condyles of femur and patella) . articulating surfaces are

usually covered with hyaline cartilage , but there is a big problem that these

articulating surfaces are not congruent, Ill give you an example on congruentsurfaces , ex: the coronoid process of ulna with the olecranon they make almost

half circle and when it sets on the trochlea it sets perfectly because the two

surfaces is congruent (one can fit on the other) , another example : the head of

the femur (3/4 of a ball) sets in the acetabulum , one of the faces is concave and

the other is convex and they are congruent .in case of the knee is not congruent .

here will do what ?will take all stress and will degenerate very early . Therefore,

if you put a cartilage filling this space the weight is going to be distributed and

this is a very good mechanical advantage .i will put extra cartilage (meniscus

which is fibrocartilaginous C shaped cartilage GRAYS), and I wont put it as acircle because if I put it as a circle Im just doing this a gain , I will fill the gaparound the surface of the circle , and I have two condyles of femur same size

same shape same direction ?? ,the answer is no . so I will put femur on the top

of tibia and fill the space with this cartilage .

I have two menisci one is lateral and one is medial , theres no such arrangementany where else , because they are not congruent two bones sitting on wrapped

table of tibia and is covered with hyaline cartilage and Im afraid that this hyalinecartilage will degenerate , and this is just a simple diagram of the knee joint , two

This is the condyle of the femur sets on the

condyle of tibia a few very small area , and we

see laterally and medially the condyles they go

away from the condyles sub-epithelia and that

means the whole load of the body weight is

coming through the condyles of the femur and

they are transmitted to the condyles of tibia

through very small area , the articular cartilage
http://en.wikipedia.org/wiki/Quadricepshttp://en.wikipedia.org/wiki/Quadriceps


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condyles you can see that lateral meniscus is larger than

the medial meniscus , two tibial condyles they are called plateau , they are not

the same the lateral one is sloppy and the medial one is not sloppy , and that is

one of the reason that cause a problem because the two surfaces of tibia are not

at the same level so NOW we know why we have a menisci .

Just like any other synovial joint it has a capsule , it has two arrangement

External = fibrous Internal = synovial membrane .


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External fibrous membrane : is dense irregular fibrous tissue and theres a holein it , we dont find a hole in the capsule of elbow or ankle but theres a hole inthe capsule of the shoulder , what passes through the capsule of the shoulder ?

long head of biceps , here popliteus muscle will pass through this hole because

the knee will be locked and you need to unlock it therefore you need a hole .

The synovial membrane : the general rule is that synovial membrane is going to

restrict synovial fluid , will line the capsule in the inside ,will line any non-

articular surface i.e once it reaches the edge of the articular cartilage it will stop ,

because we have an articular cartilage and no need for synovial membrane .this

synovial membrane will not cover the articular cartilage plus the menisci

because the menisci are still cartilages ,yes they are tough because they are

fibrocartilages but there surface is still smooth , I need the smoothness, they are

so smooth . what is also special about the synovial membrane of the knee joint is

that because of ligaments we have inside the joint and the synovial membrane

will cover these ligaments therefore the joint cavity (synovial cavity) of the knee

is not a single room there is septum and divide it into incompletely two rooms

not totally separated two rooms .

Joint cavity is divided into two connected cavities , now the knee is a special joint

and this synovial membrane will cover the non-articular surfaces will separate

into incompletely separated cavities and it extend up posterior to the patella ,

some say its a bursa , yes its a kind of bursa but this relation say that a big sacof synovial membrane is posterior to the patella and its connected to the jointcavity .

Knee joint is surrounded by many tendons and muscles and because knee joint is

moving what do I need ? I need bursae its little sac of synovial membrane with afluid to decrease friction so the tendons will not go down and they are 12 bursae

around the knee and they open into the joint cavity , Im not going to ask youabout the 12 bursea but especially we want to know supra patellar bursa ,

popliteal bursa ,and the pre patellar(between skin and patella) . of course the

gastrocnemius is a very powerful muscle and its origin from condyles of the


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femur and they cross the knee joint .

Every joint should do certain function , now the function of the knee joint is

what ? weight bearing and it has to be very stable , the fact that when I talk

about any joint I have to check stability of that joint ,cant miss it . now , will thecapsule be enough to stabilize the joint ? the answer is NO . muscles ; probably


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but they are not important factors . and these are the extra capsular ligaments

,why extra capsular ? some ligaments of joints are thickened part of the capsule ,

the knee joint has extra ones , and this is the patellar ligament which extends

from the patellar to the tibial tuberosity , this is one big stabilizing factor .

collateral ligamentsfrom the femur to the tibia medially (thats why they calledmedial collateral ligaments) this prevents the knee from being stretched laterally

, lateral collateral ligaments its femoral fibular and prevents the adduction ofthe knee , and we have oblique popliteal ligament which is extension of the

tendon ofsemimembranosus , and we have arcuate popliteal ligament from the

head of fibula .

These are the intra-articular ligament and there are few examples on it . the hip

joint has intra articular ligament which is ligamental teres (between the head of

the femur and acetabulum). the intra articular ligaments because they cross we

call it cruciate ligaments. theres ligaments that prevent lateral dislocation likepatellar ligament strengthen it anteriorly , and I should not rely on patellar

ligament, I should have another ligament because tibia will dislocate anteriorly .

if I want to prevent forward dislocation of tibia how I put a ligament , I will start

anteriorly and move it posteriorly , if I want to prevent backward movement of

the tibia on the femur I will put a ligament posteriorly and attach it anteriorly .

these are inside the capsule but outside the synovial membrane .

There is a ligament that extends anteriorly and goesposteriorly and laterally and thats the anterior cruciateligament(ACL) , and the posterior cruciate ligament (PCL)

is coming from the posterior and going medially , so

because one goes lateral and one medial they across .

these are very important stabilizing factor .now , what

kind of people have problems with cruciate ligaments ?

football players . now , the knee can do a lot of

movements ,what is the most stable position of the

knee? It is full extension when its locked ,locking is veryimportant its 5 degrees medial rotation of femur andtibia . once the knee slightly flexed become weaker ,

strongest when its in full extension and locked .


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Now ,when the football player wants to hit the ball , he will do a little pit offlexion and hit the ball if he received a kick from another player pushing the tibia

anteriorly he will stretch the anterior cruciate ligament , the PCL is less affective

than the ACL. the same movement when somebody is jumping and he lands and

he hits the bone then the femur will crush the menisci so we have little pit ofrolling laterally , the meniscus will be exposed to crushing effect . which meniscus

is more injured ?and why ? its the medial because its more fixed , the lateralhas two factors that will help the meniscus to escape away ,first the lateral

condyle is not strait so when you crush with femur it goes laterally it will escape

the crushing effect plus the popliteus muscle which comes medially goes laterally

so it will locate the femur on tibia to unlock , it has two heads one head is

attached to the condyle of the femur and the other head is attached to the

lateral meniscus .

Stability : its very stable in normal life , when basketball players jump they landand they allow little flexion because if they land strait they will have shock to the

menisci and by doing so they release the crushing effect .

shock absorbance : people of kinesiology( ) they think that num. 1

function of shock absorbance is weight distributed .

standing is the most stable joint position (extension) , once you flex it becomes

weaker , therefore for who study diseases of the knee theres a sentence that wefind in every book : in a semi flex knee this happens when its less stable .

so , the knee joint is very stable during normal life activity , Im not saying that itsstable while we play Hockey ,or football where we have situation that we have

trauma stronger than the knee .

The nerve supply according to Hiltons law whenever a nerve crossing the kneejoint supply and it has four nerves ok ! , the blood supply we have no problem we

have bulb vessels supplying the knee , this is general Idea !


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Wiki

Hilton's law expoused byJohn Hiltonin a series of medical lectures given in 1860-

1862, is the observation that in the study ofanatomy, one often finds that anervethat

innervatesajointalso tends toinnervatethemusclesthat move the joint and theskin

that covers the distal attachments of those muscles.

[1]

For example, themusculocutaneous nervesupplies theelbow jointof humans with pain

andproprioceptionfibres. It also suppliesbiceps brachii,brachialis, and the forearm

skin close to the insertion of each of those muscles.

The 2nd

mind map: knee problems

knee problems : somebody comes to you with a knee like this ! a swelling knee ,

always compare the two knees ok , ( the doctor said that he will go through this

subject very quickly because he doesnt have time ) , why should a knee swell ?!Either its a STH or either its an acute injury or a chronic injury it depends on
http://en.wikipedia.org/wiki/John_Hilton_(surgeon)http://en.wikipedia.org/wiki/John_Hilton_(surgeon)http://en.wikipedia.org/wiki/John_Hilton_(surgeon)http://en.wikipedia.org/wiki/Anatomyhttp://en.wikipedia.org/wiki/Anatomyhttp://en.wikipedia.org/wiki/Anatomyhttp://en.wikipedia.org/wiki/Nervehttp://en.wikipedia.org/wiki/Nervehttp://en.wikipedia.org/wiki/Nervehttp://en.wikipedia.org/wiki/Innervatehttp://en.wikipedia.org/wiki/Innervatehttp://en.wikipedia.org/wiki/Jointhttp://en.wikipedia.org/wiki/Jointhttp://en.wikipedia.org/wiki/Jointhttp://en.wikipedia.org/wiki/Innervatehttp://en.wikipedia.org/wiki/Innervatehttp://en.wikipedia.org/wiki/Innervatehttp://en.wikipedia.org/wiki/Musclehttp://en.wikipedia.org/wiki/Musclehttp://en.wikipedia.org/wiki/Musclehttp://en.wikipedia.org/wiki/Skinhttp://en.wikipedia.org/wiki/Skinhttp://en.wikipedia.org/wiki/Skinhttp://en.wikipedia.org/wiki/Hilton%27s_law#cite_note-0http://en.wikipedia.org/wiki/Hilton%27s_law#cite_note-0http://en.wikipedia.org/wiki/Hilton%27s_law#cite_note-0http://en.wikipedia.org/wiki/Musculocutaneous_nervehttp://en.wikipedia.org/wiki/Musculocutaneous_nervehttp://en.wikipedia.org/wiki/Musculocutaneous_nervehttp://en.wikipedia.org/wiki/Elbowhttp://en.wikipedia.org/wiki/Elbowhttp://en.wikipedia.org/wiki/Elbowhttp://en.wikipedia.org/wiki/Proprioceptionhttp://en.wikipedia.org/wiki/Proprioceptionhttp://en.wikipedia.org/wiki/Proprioceptionhttp://en.wikipedia.org/wiki/Biceps_brachiihttp://en.wikipedia.org/wiki/Biceps_brachiihttp://en.wikipedia.org/wiki/Biceps_brachiihttp://en.wikipedia.org/wiki/Brachialishttp://en.wikipedia.org/wiki/Brachialishttp://en.wikipedia.org/wiki/Brachialishttp://en.wikipedia.org/wiki/Brachialishttp://en.wikipedia.org/wiki/Biceps_brachiihttp://en.wikipedia.org/wiki/Proprioceptionhttp://en.wikipedia.org/wiki/Elbowhttp://en.wikipedia.org/wiki/Musculocutaneous_nervehttp://en.wikipedia.org/wiki/Hilton%27s_law#cite_note-0http://en.wikipedia.org/wiki/Skinhttp://en.wikipedia.org/wiki/Musclehttp://en.wikipedia.org/wiki/Innervatehttp://en.wikipedia.org/wiki/Jointhttp://en.wikipedia.org/wiki/Innervatehttp://en.wikipedia.org/wiki/Nervehttp://en.wikipedia.org/wiki/Anatomyhttp://en.wikipedia.org/wiki/John_Hilton_(surgeon)


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what type of injury , if you injure a meniscus, a meniscus is what ? its a cartilageand a cartilage has no blood vessels !!

So the interstitial fluid will moves so you will have water collection in the knee ,

and it will not happen suddenly , it will take some time for the interstitial fluid to

moves , if its blood what structures are having blood supply in the knee ? not thehyaline cartilage neither the meniscus ! but the synovial membrane and the

cruciate ligaments .

No injurywhich is the most common !! its because of other diseases , infectionsare very bad if an infection entered the knee it will be very difficult to treat !!!

Swelling around the knee y3ne pre patellar bursa outside the knee capsule .

Skin there are some skin diseases where the skin becomes red and a skin rash

develops around joints , a skin rash can be around the shoulder or the elbow , a

red skin is not an indication that there is a problem with knee ok !

Knee pain , knee pain is a big problem and referred pain you will here about it in

neuroscience 2 , sometimes the disease is in the hip and the patient complainsfrom a pain in the knee !! while the pathology is in the hip , we will deal with that

in neuroscience , so the golden rule if somebody said : I have pain in the knee ,

please examine all joints of the lower limb , examine the hip, the knee ,the ankle

and the subcapsuler joints because you never know whether the pathology is in

the hip or somewhere else ! .

When you go to the lab please pay attention to the X rays of the knee , you are

going to see lots of X rays of the knee , now to understand X rays of the knee you

have to feel the bulb the condyles the intercondyler noch of the femur , and

upper part of the tibia so we can understand X rays , the problem is that you

spend half a minute looking at a knee X ray , the total time you spend on a knee X

ray is half a minute or lets say 5 minutes , you need to sit and look at it very

carefully and analyze what structure is what , what line is what so that when youhave something up normal you see in X ray , and I will show you some bad X rays.

now in real life you see X rays , this is a lateral view of an X ray ( the doctor is

referring to the slides ) , we should always have two views lateral and

postoanterior , this is an MRI of a normal knee joint you see cruciate ligaments

you see a meniscus this is a lateral view of an MRI , whats this here ?? -referring


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to the slide - , this is condyle of a tibia and this is an intercondyler prominence

and this is what ? this is the patella ! and this is pad of fat ! the joint space is

continues behind the patella and gos up prepatellar bursa and this is the cruciateligament going from anterior to posterior and then lateral and this is the

posterior cruciate ligament , a student asked a question I couldnt hear and thedoctor answered : that they set on articular cartilage and when this meniscus is

torn I either cut the torn pieces or take the meniscus away and the result is that ;

will the head of the femur set on bone ?? the answer is no !! , its going to set onarticular cartilage ok

So these meniscus sitting on articular cartilage so the space behind them is

articular cartilage and the space below them is articular cartilage .

This is a picture that tells you that strong muscles are around the knee joint sothey are very good stabilizers , we said that this is an X ray taken from the patella, patella is the problem ! so you put the film here or here just to expose the

patella and it looks like this and it has to be what ?? the word we are using is

congruent , surfaces of the patella are congruent with the patellar surface of the

femur , where is the patellar surface of the femur ?? its anteriorly just above thecondyles of the femur ! .

Now , knee problem , here is a housemaid kneeing on the floor trying to wipe the

floor , skin of the knee is touching the floor rolling the skin on the patella andwhat will happen is that pre patellar bursa will be inflamed.

Always compared 2 joints, when you examine the definite part of knee joint and

you will find that this is under the skin, there is nothing with the knee joint.

This is a lateral view of the knee and this is anterior-posterior view.

Look at this excellent, you get the X-ray of this person, know if you not an

experience in X-ray you will say: where is the problem?!!!

You will say here is a normal tibia, here is the articular surface of the femur

(condyle), and here is the patella, so whats the problem??And as you know the fibula is not part of the knee.

The problem is patella is too superior to my right role!! I dont like this patellaposition :P


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The space here is occupied by what?? By patellar ligament, this is what?? This is a

complete tear of patellar ligament!!

When I look at this view of the knee, Is it nice?? NO, first of all the joints space

here is irregular.

Here is the condyles of the femur are touching the condyles of the tibia, this is

osteoarthritis; damage articular cartilage, inflammatory process takes place.

When I look at this very nice condyles of the femur, there is something wrong

here at the bone.

So these are some example of what someone can give you, this X-ray, whats theproblem of this patient, if you are not a mind-map man, look at the object from

an open door you will be safe.

Here is the medial condyle of the femur and here is the medial tibial condyle, the

outline is nice, intercondyler eminences, but there is an abnormal line and it

doesnt present in the another side.

If you look here, you will find the shadow of the patella, the patella is not at the

same level of the joint cavity, so dont imagine that you catch this patella and saythe knee joint is posteriorly, NO!!! The knee joint is inferiorly.

You take this view of patella, and you find that patella is fractured, whats theproblem of this person??

I know the X-ray very well I note very well I look for so many of them in my life

and then I dont like the condyles of the femur so much anterior to the condylesof the tibia, this thing rings the bill!! This means either the tibia has go back or

the femur go forward.

This knee is unstable, you cant ask the patient to step on his knee because this

knee is unstable, and if he does he might injured another ligament.

A question came in one of the previous exams,, where is the disease?

A) Patellar ligament

B) lateral fibular ligament

C) Medial fibular collateral


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D) Anterior posterior ligament

Rheumatoid arthritis: is the most common disease; damage of articular surface

(hyaline cartilage), this is the big problem

Many of your mothers, many of your grandmothers, old people in family they

complain from this pain

And the problem here is not the anterior posterior ligament.

What does the obesity do?? Increase the weight!! Right you have a very good

hyaline cartilage its going to take all of your life if you use it properly, but if youuse it improperly, you put more weighs is going to degenerate early.

Likely enough that we have the MRI show us the bad areas in the cartilages.

FINSPECIAL THNX TO M7MD 2BO 6ALEB [CARROTS \\\

Elko ma3azeh 5a9a

DONE BY : ABDALLAH MASADEH

Anatomy - Lec.15

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