Hey everyone! Welcome to Professor Long's lectures in anatomy and physiology. If you're watching these videos you either stumbled across them on the internet you're not enrolled in my class please learn the material that your instructors cover.
If you are in my class which is who these videos are intended for learn what's covered in the note set, what I write on the board. This is what I'm wanting you to learn. We're going to set the foundation so you can add detail later.
Now, if you've been following along, we've been covering some bone lectures and we did some articulations. We did the classifications of joints. Never a fun subject. But it is what it is.
Now we're going to talk about a couple of the major joints in the body. And then we're going to do some joint motions. I'm going to demonstrate some of that. So if you're following along in my notes and you're in my class, we're on page 48. If you're not in my class... If you email me, maybe I can send you the document.
You can download it or you can call what's called the student bookstore or the Del Mar College bookstore and see if they'll mail you a copy of my note set. A lot of students seem to be ordering those now. Maybe they're helpful to you guys. They're about $12 to $15.
They're not real expensive. Now, oh, by the way, any proceeds from that go to a scholarship here at Del Mar. When it comes to...
The joints, we could spend an entire semester just talking about the shoulder or just the elbow or just the knee. There's a lot of time we could spend on them. They're very complex structures. All these articulations are extremely complex. I'm going to spend a little time talking about the knee joint and how it's...
structured and how it functions and really about the the ligaments in it because the knee is injured a lot especially with youth sports and athletics and all you know adult sports people tear up their knees a lot skiing and things and we're going to talk a little bit about the intervertebral joints, the disc, because those tend to loom very large in everyday life. Not that we don't have injuries to other joints, but these are the major ones. If you learn it, get a good solid understanding of these, you'll understand some of the others. So when it comes to our knee, our knee is very complex. So I'm going to draw a picture over here off to the side.
If I look at the knee from an anterior view, the femur comes down and does this. The condyles of the femur are like this. And it looks something like that.
That's a little bit warped, but you get the idea. And then we have the tibia coming across like this, what's called the tibial plateau, where the tibial condyles are, and they're a little bit dished out. Okay, this is all called the tibial plateau, plateau for flat or plate, and they're structured like this.
Now sitting in front of all of this would be your patella. I'm drawing the the prettiest of patellas but it would look something like that the base of the patella and the apex if you've been studying in lab now if I drew this from a lateral view I would have the distal femur do this the proximal tibia does this and your patella would sit here something like this sorry let me get that right fit together Now there's a bunch of muscles surrounding the knee joint. The knee joint provides a lot of power for us to run and jump and doing leg extensions and kicking things.
Now, The knee takes a tremendous pounding as we walk. Every step you take the knee bones are banging on to each other and if you're running and you stop and try to cut like if you're playing tennis or in football or if you're in basketball and you run straight and try to stop. those forces of your body will try to, the momentum will try to rip the knee joint apart. And I've actually seen it happen. But most of the ligaments and the muscles and tendons around the knee joint help stabilize it so it doesn't rip apart.
Which is why athletes who don't want joint injuries should work out. The stronger and more tense the muscles are, the more tighter they pull those joints together, and the more difficult it is to injure them and dislocate them or get what's called a subluxation. The word subluxation means dislocation. So we're going to look at a bunch of the ligaments and tendons surrounding this. Now, if I were to put a bunch of muscles back here, the muscles on the back of the leg would be called the hamstrings.
I don't know if y'all can see all that all the way up there, but we would have the hamstrings on the back, and then we would have the quads or quadriceps muscles on the front. We've covered those somewhat in the lab. Let me make sure all that's on your viewing screen so that you can see.
Let me move my camera just a hair, okay? So. Now, the muscles called the quadriceps muscles and the hamstrings actually attach to the tibia with some tendons. And one of the tendons that envelops the patella is called the patellar tendon.
Now, on the backside, there is a small ligament here that also holds the patella to the tibia so it doesn't float off. And that's actually called the patellar ligament. But the rest of this structure would be called the patellar tendon.
The patellar tendon connects the quadriceps to the tibial tuberosity. When you extend your leg, those muscles pull on that tibial tuberosity, and the patella helps. spread that that um the tension or the torque um properly across the joint and it's really the patellar tendon that does more work than the patellar ligament so if you look in my note set I talk about the patellar tendon. Now, the patellar ligament is a little ligament that holds the patella to the tibia and prevents it from sliding around. But it's the patellar tendon that does a whole bunch of this.
And we call this an anterior stabilizer. Okay, and that would be coming down here and completely envelop the patella. And it's actually part of the connective tissue that they take if they're going to do what's called an AC repair. the anterior cruciate ligament in the ACL repair is where they would literally cut the center stripe out here.
One type of repair. There's a number of ways that you can do it. You can take some of the hamstring tendon.
A lot of people do the patellar tendon and some people do a graft from a cadaver. But when they do the patellar tendon graft, they actually cut a piece of this bone out of the kneecap. Take this out and run it through to do an AC repair. It's a very strong tendon.
And it stabilizes the knee in an anterior direction. So if I were to push on your knee this way, it stabilizes it. Or if you've ever seen an athlete get injured on a field like in football games and the doctor bends their knee and you see them pulling and pushing on the tibia, they're trying to see how much movement they have here. This is going to prevent it from ripping apart, but they're testing the ACL and the PCL ligament.
But this is an anterior stabilizer so that we don't rip the... the front of the knee apart. On the posterior surface of the knee there are what are called the popliteal or some people say popliteal ligaments.
The popliteal or popliteal ligaments are posterior stabilizers. And there are a couple of ligaments. There's one that connects from the femur to the tibia, and there's one that connects from the femur to the fibula.
And they're very tiny ligaments, and they do a little bit of posterior stabilization, but not a lot. Now, I'm going to erase this part of the patella, and we're going to talk about the ACL. and the PCL.
You hear these terms thrown around a lot. What do they mean? ACL stands for anterior cruciate ligament. Cruciate comes from the same word as crucifix. Let me make sure everything's within the screen here.
Yeah, we can see very good. So the reason it's called the anterior and the posterior cruciate, the PCL, is because one runs in front of the other. The other one runs posterior or behind the other and they crisscross. So they look like what we call a crucifix or cruciate. Now it actually turns out that one of them inserts into the bone here and then runs across this way and inserts into the bone here.
The other ligament has actually grown into the bone some and crosses behind this one. This way. And if I look inside the knee joint, they kind of do this.
I'll see the ACL and the PCL crossing each other. One is in front of the other. Now what's unique about both of these is that both are anterior and posterior stabilizers. And they play the largest role in maintaining the alignment of the knee joint. They maintain the alignment of the tibia and the femur.
So if I were to pull here, you can see that the ACL and the PCL would become tight and it would prevent me from ripping off. If I push, they would also tighten up. Now the ACL does a little bit more anterior stabilization, the PCL does a little bit more posterior stabilization, but if you tore one of them, the other one would pick up the slack. And when you see someone do that what's called a Lachman's test, they're wiggling the tibia to see if the ACL and PCL are tight. If they are, you won't wiggle it as much.
If it moves, well, you may have torn one of those and you need to get an MRI. MRI will see tears in those ligaments. So they're deep inside the knee here and they'll both anterior and posterior stabilizers. And finally, there's what we call the LCL and the MCL.
So I'm going to erase this. And we'll add those on and I'll use color coding I guess. So the MCL stands for the medial collateral ligament and some people will also call this the the tibial. collateral ligament. Remember the tibia is more medial and the fibula is lateral down here like this and there's a ligament that sits right here that joins on the side called the MCL because it's the medial collateral ligament.
It is a medial stabilizer. When you see an athlete get kind of bent over backwards and their leg their knee gets pulled this way You might be damaging the MCL or medial collateral ligament. The other one would sit over here and connect to the fibula And so it is also called the fibular collateral ligament, or more commonly called the LCL, which stands for lateral collateral. A collateral goes along the side or goes along with. So the lateral collateral ligament is a lateral stabilizer.
And people can tear their MCL and their LCL as well. And you can tear multiple ligaments. Some people tear both the ACL and the PCL.
Some people tear them all up. But all of these ligaments and tendons are holding the knee joint together and stabilizing it. And again, the stronger your muscles are, the more stable your joints can be. That's why athletes work out as much as they do.
For example, if you saw someone like... you know, a 300-pound lineman running in the NFL, and then they try to stop. Just imagine all that force trying to rip the knee joint apart.
But when they tighten up the quads, that pull is so tight, it helps prevent the joint from ripping apart. So you should know all of those particular ligaments and which one stabilizes where. Now, one of the questions in my note set is, what is the most common athletic knee injury? lot of people will say well it's an ACL injury. No, you're patently false.
It's wrong. So let me show you something. I'm going to redraw the knee joint from an anterior view. Something like this, okay.
Now if you took a rounded knuckle and you try to do push-ups on a single knuckle or press down on a tabletop, it will hurt as you smash on the bone because the periosteum has nerves in it. Well, if I look at the end of the tibia and the end of the femur, they don't make a perfectly flat surface. One is more rounded than the other and a lot of pressure can be put on a single point.
So we need to distribute the weight over a larger surface area. like doing push-ups on your flat fists is much nicer than doing push-ups on your knuckles. The other thing is this, we need a shock absorber here, and so there's a piece of cartilage that fits in here that conforms to the shape of the distal femur and the plateau of the fibula, I'm sorry, of the tibia, and we call that the meniscus of the knee. And people refer to the medial or lateral meniscus.
So if I put your fibula there, this would be the lateral meniscus on the outside of the knee. This would be the medial part of the meniscus. Now, if I could remove the femur and look down on top of the meniscus, or if I could pull it out and look at it this way, it's shaped like a figure eight.
And it's... Got openings on both sides almost like a little sleep like a little mask or something. Now the outer edge is much thicker than the medial edges of these so that it conforms to the surface so they're thicker here and they get real thin where it's hollowed out and if I look down on top of this if I can remove the femur I can see the tibial plateau through here and that's partially where some of these ACL and PCLs go. Now The most common athletic knee injury is a torn meniscus because when we twist, have twisting motions like if you hit a ball in tennis, well what you're doing is you're having a torsion on the flatter thinner part of this and let me grab the sheet of paper and show you something.
It's almost as if I did this and if I tear a piece of paper this piece of paper can flap up and down in here and because there's fluid in the knee as the meniscus flaps up and down it can rough up the hyaline cartilage or the articular cartilage and create arthritis. So people tear their meniscus and get a little partial tear in here sometimes. And, you know, some areas are torn more commonly than others, but you can have the posterior horn or the anterior horn of the medial or the posterior and anterior horn of the lateral meniscus torn.
One of the things that they used to do in surgery is completely remove the entire meniscus, and then that was causing people's knees to just develop bad arthritis and need knee replacements. So now they can insert a couple of little instruments. One is a camera and one is a shaver.
And they'll just shave out the torn part and leave as much of the intact meniscus there to prevent arthritis from setting in earlier in life. So people who have a torn meniscus, it's what's called a knee arthroscopy. And if you look at what's called arthroscopy.
That means to scope the joint. They stick a camera in there, a video scope, look around, see the damage, stick another shaving device, an electrical shaver, through another small port. They pump some fluid in there to open it up, and they shave out the torn part, pull everything out, put a stitch or a Band-Aid on it, and send you home. So it's definitely...
not a bad procedure and it's going to put off getting a knee replacement later on. So a torn meniscus is the most common athletic knee injury. Okay. And I think there's a question in my note set that says, why do young females tear?
their ACL and or PCL more commonly than young males. You would think with football and baseball that kids would tear their ACL a lot more and you do see it a lot in football but in volleyball and basketball when we jump and land we can hyper extend the joint and it turns out that on average females have a little bit more joint laxity to be lax is like to relax is where you kind of chill and when we have laxity in the joint or more more flexibility in the joint it's because our sex hormones like testosterone cause an increased buildup of not only muscle tissue but some of the connective tissues and they make them a little stiffer. That's why, on average, males are less flexible than females. It doesn't mean we don't have super flexible males and some females who are inflexible. But female hormones don't increase the connective tissue growth as much as male sex hormones.
And so some females have very, very lax joints. Some males do too, and the more flexible you are, the more flexible you are. especially if you're someone who stands up and your knee hyper extends or goes backwards, then you might be more susceptible to an ACL tear. So, you know, there's a bunch of exercises that you can do to strengthen the muscles. Squats, leg extensions, quadriceps strengthening, so that when you do jump and land and tighten your muscles, it helps tighten up the joint.
Another problem for females is that the... And some boys get this, some males, but a lot of females will have the patella ride in the patellar groove and get knee pain and start to develop arthritis on the back. the patella because it fits in that patellar groove and again Strengthening up the quads or they do what's called McConnell taping You use the special tape to tape around the little X around the kneecap or what's called a patellar stabilizer Which is a little sleeve that has the cutout for your patella and some of them You know have straps that help stabilize the patella and prevent that knee pain from happening You know all sorts of quadriceps strengthening.
If you're having any of these issues, talk to your sports medicine doctor or orthopedic doctor and learn how to train to prevent those injuries so that you can have a long, healthy, athletic career. Anyway, that's the knee joint. I wanted to talk about that.
And then the last thing I'm going to talk about today is the intervertebral discs. We're not going to spend a tremendous amount of time on it, but if I look from a lateral viewpoint at the discs or at the vertebrae. So let's say I have a vertebrae.
that's sitting like this and let's say I'm going to look at a thoracic vertebra so we have these articular facets and then we have the spinous process sticking down and then I have the next thoracic vertebra that has its superior articular facet and the inferior articular facet and the body of the vertebra between the bodies of the vertebrae is a fibrocartilage pad called the intervertebral disc because it's between the vertebrae and it is disc shaped okay that creates this intervertebral foramen by the way where your spinal cord would be running through here and the nerves all of your spinal nerves will extend out through that foramen and we've done some of this anatomy in lab now If I pulled this disc out and looked at it, it is disc shaped and it's a little bit thick. If I could slice it in half like this, I would notice that the outer edges are a thick band of fibrous connective tissue. And because it goes in a ring, that fibrous connective tissue is called the Annulus fibrosus.
Anu means ring shape like anus. Okay so the annulus fibrosus is a ring of fibrous connective tissue or it's actually fibrocartilage I should say. It's a thick ring of fibrocartilage rich in fibrous connective tissue and collagen. Now inside, if you could break it open, there's some fluid in here, like a very thick gelatinous mass. And that fluid or gel is called the nucleus pulposus.
like a pulp, okay? And that provides a little shock absorption, some hydraulic absorption of pressures so that when we jump they act like a really good shock absorber and it keeps the joint spacing where the nerve comes out just right. Now our vertebrae are designed to rotate like this and they're designed to allow us to flex.
What they're not designed to do is slide across each other. So if I were flexed and I grabbed a heavy weight, the weight would be trying to pull my upper body down And my lower body is trying to lift. And if I slide those vertebrae across each other, so when I flex this joint, I'm just going to draw the bodies of the vertebrae.
But if I flex this joint, what that can do is it can compress the disc like this. And the fluid can allow it to bulge and move around. If I were to pull this vertebrae down by lifting something heavy and this one back, you can see how they can shear here.
create maybe a weak spot and rip part of this. Maybe it's not a complete tear, but I've made the wall thinner in one area so that when I do stand up now I'm getting a bulge in the disc where that weak spot is and balloons out. That bulge in the disc can compress on the nerve and create all sorts of problems. And so we call that, sometimes people call that a slipped or bulged disc. In a slipped or bulged disc, what that really means for us is that it is a partial tear, usually, of the annulus fibrosus.
causing the nucleus pulposus to bulge out some. And it can irritate nerves. That's why when we hurt our spine, we tend to have nerve problems. Now, what if I completely tear this, and some of the nucleus pulposus leaks out?
Now the disc can actually compress and it's almost like a flat tire. It loses all its fluid and it flattens out. And now the discs, the joint space becomes compromised pressing on that. nerve and so very often this will be referred to as what we call a herniated disc or a ruptured disc so our herniated or ruptured discs is a complete tear of the annulus fibrosis and loss of the nucleus pulposus. And when that can compromise the spacing here also revolve resulting in nerve damage or nerve irritation.
Okay so when people injure their back they also have problems either radiating out down their arm or down their leg like sciatica and other things and there are indications that you have a compression of nerve you may have damaged one of the discs in the back. Now, some surgeries are pretty rough. In some instances, they'll cut a piece of bone out of your hip, spread this out, and stick the bone in there and put a little titanium cage and let it heal together or fuse the discs so that they lose their motion, but at least you're no longer irritating the nerve. There's some new procedures now.
where they're actually doing arthroscopic surgery of your discs where they make two little puncture wounds go in shave it out do what they need to do and get out there's also laminectomies where they can remove a little bit of bone so it's not irritating the nerve but if you do have those problems make sure you see a very competent and qualified neurosurgeon or orthopedic surgeon that specializes in spines okay anyway that's what I wanted you to know about the discs because you'll see that and for those of you who work in the hospital patient transfer is a big deal properly transferring a patient, you never want to flex your joints and lift. You always want to try to lift with the knees if at all possible. Or when you reach across the table and transfer a patient from a gurney or bed onto a surgical table.
and back. People will often bend over and do this and you can get damage to your discs of your back. So they teach you proper back hygiene and the proper way to transfer and lift patients and it's really, really important that you keep your spine correct.
Even if you're lifting weights, don't bend over and pick up the weights. Bend your knees and keep your spine straight. It's really important for proper back hygiene to protect those discs.
Anyway, listen. Learn the ligaments and what they do around the knee. Learn the intervertebral disc.
I hope you had as much fun as I did. I hope you learned something. Do it till you can't stand it.
Do it till you understand it. Do it till you can teach this to a group of fifth graders. And I'll see you in the next video. Study like you never studied before.