welcome to module 3 per D the appendicular skeleton lower in this module we'll be covering the pelvic girdle and the lower limbs recall that a girdle is a belt-like structure encircling the body and in the interior Superior view we can see the pelvic girdle is a true girdle because it makes a full ring when the pelvis is attached to the sacrum the full ring of the pelvic girdle is made up of seven bones and the pelvis itself is made up of six Bones the pelvis has right and left ilium ischium and pubic bones so one of each of these on the right and one of each of these on the left ilium and ischium are the singular terms for the bones whereas Ilya and ishia are the plural terms the last bone in the pelvic girdle is the sacrum which is part of the spine and axial skeleton not a part of the pelvis but when the pelvis attaches to the sacrum the pelvic girdle is complete so what does this pelvic girdle do well similar to the shoulder girdle it attaches the lower limbs to the body and by doing so transmits forces from the lower limbs to the axial skeleton to the vertebral column in the shoulder girdle Force transmission to the axial skeleton was at the minibrium of the sternum like the shoulder girdle the pelvic girdle provides areas for muscle attachment but unlike the shoulder girdle the pelvic girdle also provides support and balance to her trunk as well as support and protection to our organs in this frontal view you can see a transection of the right hip lateral is on the left medial is on the right and superiors on the top and here you can see how the femur is really well surrounded in the acetabulum of the pelvis I hope you can appreciate how secure this attachment of the lower limb is to the body compared to the attachment of the shoulder girdle to the axial skeleton you can see the transection of lots of large and small muscles in this area before we get into the details let's learn the names of the bones in the right lower limb on the left you have the anterior View and on the right a posterior view of the right lower limb with the medial aspect of these you use in the middle starting at the top we have our hip bone our oscoxae femur patella tibia fibula tarsals metatarsals and phalanges starting at the pelvis remember it's made up of six bones two Ilia two ischia two pubis bones on the ilium we have our iliac crest this is the top portion of the ilium and is a site of lots of muscle attachment you may be able to palpate this crust on yourself next we have the anterior superior iliac spine and this is at the front of the crest you may be able to feel these on yourself as well they're your hip bones they too are a site for muscle attachment sometimes we call these your Aces so a-s-i-s however on tests you have to write out all of the acronyms not just for Aces but for everything in the course so you would have to write the anterior superior iliac spine next we have our sacroiliac joints and this is where you have the articulation of the sacrum with the right and left Ilia back in 1989 there was a Canadian rapper named Maestro Fresh West that had a song titled let your backbone slide and in it had a couple of lyrics so many suckers on my sacroiliac it's like a rap sack backpack and the reason why I bring this up is it's not often that anatomical terms make it into music let alone good music so some Anonymous have shared that they thought this was pretty exciting to be included in such a popular song and if you aren't familiar with it I know it's an old song but look it up and give it a listen it might give you a laugh moving on to our ischium we have our ischial tuberosities and this is also a site of muscle attachment and it's what you're sitting on so it's often called your sits bones in the pubis we have our pubic symphysis and we talked about this previously in the cartilage lecture remember that the joint here is a fibrocartilage joint this joint is very the pubic symphysis this is very interior it's very stable it doesn't allow for much movement and quite frankly it's considered an immovable joint we also have our pubic tubercle and pubic Crest the pubic tubercle is the attachment point for the inguinal ligament and the pubic Crest is right here is the attachment site for muscle we can see a little bit of our acetabulum here and the acetabulum is made up of all three bones in the pelvis on each side right and left and it's the socket for the head of the femur it's your hip joint the obturator foramen is the big obvious hole in the anterior aspect of your pelvis lots of things are going to pass through this foramen blood vessels nerves and if it wasn't there the vessels from Insider trunk would have problems exiting into our limbs also our pelvis would be much more heavy if we didn't have these foramen so that the foramen help us to reduce the weight here you can see the position of the pelvis in the body and I've gotten two arrows on just the First shows the iliac crest so if you start it at your waist and slid your hand down on your side you could feel this first lump that would be your iliac crest if you go down too far though you'll be down more over your hip area you'll be feeling your greater trochanter which we'll talk about more in a couple of slides if you move your foot on the ground like you're squashing a bug and you feel this large lump passing under your hand as you move your foot that's the greater trochanter of the femur so you have to move up to feel that iliac crust now back to the pelvis what I'm showing you here is the right coxal or hip bone and the ilium is in this sort of grayish beige the pubis is in the sort of purpley color and your ischiums in the pink and this is a lateral view so you're looking in A sagittal plane from lateral to medial so from outside of the pelvis to inside the pelvis please note that anterior is on the right side of the slide and I'm going to discuss the features per bone here but you could re-list the features in the pelvis similarly to how we did in the scapula so grouping spines tuberosities notches Etc so the features of the ilium that you can see here again you can see that iliac crest you can see the body of the ilium you can see the Asus or the anterior superior iliac spine we can also see our anterior inferior iliac spine and this one's difficult to populate much more so than the aces we also have our greater sciatic notch on the posterior aspect of the hip bone this will be a boundary for the greater side of foramen it contains lots of important structures like Bane's artery nerves a few muscles and Etc we also have our posterior superior iliac spine sometimes called pieces again you'd have to write out the full name on a test but some people have dimples right by where their pieces are and it's made from a little ligament from the bony prominence to the skin not everybody has it though we also have posterior inferior iliac spines and these are a part of an important space the greater sciatic foramen and they're an attachment point for some other structures we also have our gluteal lines anterior inferior and posterior and these are attachment points for the gluteal muscle group moving to the ischium again we have our ischial tuberosity remember this was our sits bones our body of the ischium and our ischial spine and the ischial spine has a ligament that's attached to it that's important to form these spaces of the greater and lesser sciatic foramen here we have our lesser sciatic Notch and this will be part of the boundary for the Lesser sciatic foramen and it too will also contain some important structures the foramen not the notch we have the ramus of our ischium and this is important in defining spaces for your urogenital triangle but we'll cover later in the reproductive system some features of the pubis bone that we can see here is the pubic tubercle and again this is where the inguinal ligament will attach we also have the superior ramus of the pubis as well as the inferior ramus of the pubis the inferior ramus of the pubis will join with the ramus of the ischium to form your ischial pubic or conjoint ramus which is one of the Bony boundaries of your urogenital triangle in your perineum that's your pelvic floor and you'll cover that again in the reproductive system here you can see the acetablium really clearly and you can very clearly see that all three bones are contributing to this structure and again this is where the lower limb is going to connect to the pelvis you can see the obturator foramen it's a big hole you can see it in pretty much every View and you can see very clearly that the obturator foramen is bounded by the ischium and pubis Bones this is still a right coxal bone so you still have the right ilium ischium and pubis but you're looking at it in a medial view fro so from medial to lateral or inside to out note that anterior is on the left side of the slide this time looking at the features of the ilium we can still see the iliac crest Superior and inferior anterior and posterior iliac spines we can see the greater sciatic notch in the body of the ilium but we can also see how if you follow that iliac crest here back you can see the iliac tuberosity and this is the site of ligament and muscle attachment we can also see that auricular surface and this a regular surface is where where the ilium is going to attach to one side of the sacrum there are no new features or structures of the ischium that you can see in this view just the same features that we could see in the lateral view so we can see the body of the ischium the ischial spine lesser sciatic Notch ischial tuberosity and ischial ramus in this view of the pubis we can still see the superior inferior ramus of the Pugi excuse me inferior Rami of the pubis as well as the pubic tubercle that will that we saw in that lateral image and we can see the pubic Crest in the synthesis that we saw previously we can still see the obturator foramen which is to be expected because again it's a very large hole in our coxal bone next we need to discuss the false and true pelvis the top image here is an anterior Superior View and the bottom is a midsagittal plane you can see the division here on the small little left image the Bony pelvis is divided into Superior and inferior portions by the pelvic Rim boundary making false and true pelvis respectfully the brim forms the inlet to the pelvic cavity from the abdomen but to trace that brim you start posteriorly at the sacral Promontory and if you continue laterally and inferiorly along the arcuate lines of the two iliac bones and then continue inferiorly along the pectinal lines of the pubic bones and then lastly Trace anteriorly to the pubic Crest to the superior portion of the pubic symphysis you have your pelvic brim so that's this area here these points form an oblique plane that's higher in the back than it is in the front and you can see it much better in this bottom sagittal view than you can in the top the circumference of this plane is the pelvic brim so again it's this area here you can see the superior portion would be the false pelvis shown in that sort of Pinky color now the plane of the pelvic Outlet is made by points from the ischial tuberosity and the coccyx the pelvic axis is an imaginary line that curves through the true pelvis from the central point of the plane of the pelvic Outlet to the pelvic brim note this is the route that is taken by a baby's head as it descends through the pelvis during childbirth again you can see the false pelvis and the true pelvis the false pelvis being above the pelvic Rim so here whereas the true pelvis is below the pelvic Rim this is this same pelvis on both sides of the slide I have both are an interior Superior view on the left it's showing you the false pelvis highlighted in pink that's your pelvic Rim there you can see it in that sort of beigey color and on this side same view but showing you the true pelvis below that pelvic Rim the false or greater pelvis shown in pink on the left the borders are the lumbar vertebrae posteriorly the upper parts of the hip bones laterally and the abdominal wall anteriorly it encloses space that's part of the lower abdomen and contains the superior portion of the bladder lower intestines and in females the uterus ovaries and uterine tubes the true or lesser pelvis shown in blue here on the right again the borders are the sacrum and coccyx posteriorly the inferior portions of the ilium and ischium laterally and the pivot bones interiorly it surrounds the pelvic cavity and contains the rectum bladder and vagina and cervix of the uterus and females and the prostate in males to sum up the true or lesser pelvis the superior opening is at the pelvic brim so here that's the Superior or top opening and the inferior opening is called the pelvic outlet and I defined that on the previous slide and it's covered by muscles in the floor of the pelvis there are some sex differences with our hip bones and so here I'm just comparing female and male pelvis we have a general structural difference female tend to have light and thin and slightly smaller pelvis than a male tends to have heavier and thicker pelvis the false or greater pelvis in females is shallow whereas in males it's deep the pelvic brim or Inlet is wide and more oval in females and it is more narrow and heart-shaped in males the acetabulum in females tend to be more small and face interiorly whereas in males they tend to be large and face laterally the obturator foramen in females tend to be more oval whereas for males they tend to be round the pubic Arch tends to be at an angle of greater than 90 degrees in females and lesser than 90 degrees in males for the iliac crests females have less curved iliac crests whereas males have more curved and to see this think of riding your bike over the surface so the males have a tighter curve over this iliac crest than females do there is a less vertical ilium in females and more vertical in males the greater sciatic Notch is wider in females than it is in males it's about 90 degrees here where in males it looks almost like an inverted V the sacrum is shorter and wider and it's less curved interiorly whereas the males sacrum is longer narrower and and it curves in more anteriorly the pelvic Outlet in females is wider and the males is more narrow so this space here the ischial tuberosities in females tend to be shorter further apart and more medially projecting whereas males they're longer closer together and more laterally projecting so the ischial tuberosities these difference combined make it easier for a female to pass a baby through their pelvis given that females pelvis are wider in general with a wider pelvic brim wider Outlets relative to males so females could pass a baby easier through that space before we go through the last four main sections of the lower limb remember that the lower limb carries the weight of the entire body and is subjected to exceptional forces there is about one and a half times body weight with each step that we take during walking but three to seven times our body weight when we're running and jumping the terminology is really important for this section similar to the Upper Limb such that the thigh is from the hip to knee and I've shown it here in light blue the leg is from knee to the ankle and it's circled in purple the ankle is circled in dark blue and the foot is circled in the green and pink sections there so just like for the Upper Limb if there's a question on the test and it's from the thigh and you think or answer it's in the leg you will be incorrect starting in the thigh we'll go over the features of the femur proximal to distal shown is a right femur in an anterior and posterior view with medial being located here in the middle for both of these views the femur is the portion of the femur that fits in the acetabulum of the pelvic bones and together these form the hip joints the neck is the next region separating the head from the shaft of the femur if a bone has a head it will also have a neck the neck of the femur acts like a cylindrical strut attaching the head to the shaft of the femur and it is angled and projects Superior immediately from the shaft to permit an increased range of motion at the hip joint next we have our greater trochanters and these are on the lateral side and many muscles are going to attach to the site the lesser trochanter is on the medial side of the femur and it's a bit smaller than the greater trochanter but it too is an attachment site for muscles it's important to note the difference between the term trochanter and tubercle in general trochanters are large bony projections for muscle attachment and they can't be used interchangeably with a tubercle so make sure when you're referring to the features on the femurs that you realize you're dealing with greater and lesser trochanters not tubercles here we can see the intratrochanteric line on the anterior aspect and the intratrochantera crest on the posterior aspect both of these are bony projections the intra-trochanteric line on the anterior portion is connecting the greater and lesser trochanters and it's a muscle attachment site the intertrochanteric crest on the posterior aspect is a bony projection again for muscle attachments next you can see the gluteal tuberosity and this is a raised surface on the posterior aspect of the femur where the gluteal muscles will attach and lastly we have the shaft or the body of the femur and you can see it's labeled in the middle but really the shaft is this whole portion between the ends of the bones next we have our linear aspra and this is a ridge for muscle attachment and it really could have been covered in more of the proximal end features because it extends along the posterior surface until the widened area at the floor of the popliteal fossa behind the knee but it continues from the gluteal tuberosity all the way down we also have our epicondyle so we have lateral and medial epicondyls and you can palpate these unless you're really really muscular the Bony elevations of the non-articular surfaces are attachment points for the collateral ligaments the condyles we can see best from the back they're rounded posteriorly and they're flatter on the bottom and the anterior portion they have this sort of v-shaped trench and that will be for the patella to articulate with the femur the lateral surfaces are larger and steeper than the medial surfaces next we have our patella surface and we'll discuss that a little bit more in just a couple of slides here you can see the intercondylar fossa and this is the space on the posterior aspect of the femur that's between the two large condyles the walls of the fossa have facets two facets for the superior attachment of the cruciate ligaments here we have the adductor tubercle and it's just posterior superiorly to the medial epicondyle and it's a bony ledge on the medial side for muscle attachment specifically for the insertion of adductor Magnus posteriorly to the lateral epicondyle is the attachment for the lateral head of the gastroc and poplitealis muscle here in this articulated view with anterior on the left and posterior of the right of a right lower limb you can see how the head of the femur is articulating with the acetabulum of the pelvis you can see how the neck moves the shaft portion of the femur away from the pelvis to help prevent bony collisions which increases the range of motion permitted at that joint you can see the condyles that are covered in cartilage and the way that they're articulating between the femur and the tibia to form your knee joint and you can see how the patella is sitting in that v-shaped trench between the condyles on the anterior aspect of the femur So speaking of the patella here's the patella in a little more detail the patella is an other bone in the thigh and here it's shown in the interior view on the left and posterior view on the right it's a sesame white bone it's the largest sesamoid bone in our body and it's not directly connected to any other bone which is why it's a sesamoid bone it's held in place by a tendon and a ligament it's slightly triangular-ish in shape with the Apex pointing down and that's going to connect the patella to the tibia via the patellar ligament and the base is broader and it's going to provide a thick attachment for the tendon of the quadricep femoris muscle here you can see the quadriceps muscle tendon and the patellar ligament on the inferior aspect and it's important to note that the patella isn't flat but it has these two areas on the back of it to articulate with the femur and you can see that here in the transected view the whole point of having a sesamoid bone at this location is to increase the leverage and which increases the moment that the muscle can generate about the knee joint looking at the right leg with anterior on the left and posterior on the right and medial in the middle remember that the leg is from knee to ankle the leg is made up of two bones the tibia and the fibula the tibia is more medial and it's the one you can feel and it's the one we call our shin bone the fibula is more lateral and it's typically buried in muscle and it's a small bone so you likely can't feel it an easy way to remember which one's which is fibula is lateral and I just put that little mnemonic over here between the tibia and fibula is a really tight membrane the interosseous membrane and it's a between bone membrane that adds structure and location for muscle attachment again it's the tibia that's articulating with the femur to form the knee joint the fibula does not attach to the steamer at all here I'm showing a disarticulated right leg and an anterior view on the left and a posterior view on the right with medial of both of these views in the middle if we go over the tibia first you can see the medial and lateral condyles of the tibia and these are going to articulate or form joints with the medial and lateral condyles of the femur to form the knee joint we also have this intercondular Eminence which is a raised portion of the intercogular region of the tibial plateau and it actually has six distinct facets for the attachment of the menisci and the cruciate ligaments here you can see the tubule tuberosity and it's on the front of the tibia just below the condyle so just on the anterior surface inferior to the condyles just below the knee joint you can feel this if you start at your patella and move distally next we have the anterior border and this is a sharp portion of the bone that descends from the tibial tuberosity and you can easily feel it on the front of your shin at the distal end of the tibia we have our medial malleolus and this is a large bony projection and medial bump at the ankle and you can feel it because it has lots of muscle attachment here but it also is for stability at the ankle joint which we'll discuss in more detail in a few slides lastly we have this fibular Notch and the fibular notch is located on the distal tibia for articulation with the fibula looking at the fibula proximal the distal now we can see the head of the fibula and it's going to form a joint with the tibia we have our lateral malleolus it's a distal big bony projection that you can feel on the lateral side of your ankle again because of muscle attachment but also to add stability to the ankle and it's important to note you only have a medial malleolus in your tibia and only a lateral malleolus on the fibula and both of these are going to fit on either side of that football metallis to help stabilize the ankle joint and they're also for muscle attachment here again we have an articulated view of the right leg and on the left is our anterior view right is the posterior view of that right leg with medial for both views located in the middle and what you can see right away is that interosseous membrane and remember it's adding structure as well as a site for muscle attachment its connective tissue between the bones and it's like a tough ligament structure adding stability to the leg and making the legs stronger without having to have it heavier because there's less bone and muscles can easily attach there and if you didn't have it there you would just have a hole between the bones looking at the Two Joints we have two tibiofibular joints and there's little to no movement at these and it's not like the forearm they are not similar in function and you cannot do pronation and supination with your leg therefore these joints are there for stability not flexibility so the first one here is the Superior or proximal tibiofibular joint whereas the second one is the inferior or distal tibiofibular joint and again which of the tibia and fibular are weight-bearing it's the tibia that fibula does not articulate with the femur it is a non-weight-bearing bone but it does have an important role in stabilization at the ankle so before leaving this slide I want to point out the ankle joint so here you have the talus which is a tarsal bone that's in the foot articulating with both the tibia and the fibula to make the ankle joint looking at the ankle joints a little bit more closely recall from the terminology module that the ankle joint does dorsi and plantar flexion so both the tibia and the fibula articulate with the talus to form ankle joints and where the tibia and fibula join together they're going to provide the last bit of the socket for the talus to make up these ankle joints so the three ankle joints that you have and they are three separate joints is the tibio tailor joint so that's between the tibia and the talus the fibulo tailor joint between the fibula and the talus as well as that inferior tibiofibular joint and again you need this joint between the tibia and the fibula the distal aspect so to properly make the socket for which the top of the tailless will be able to articulate with these other two bones otherwise when you loaded this limb these bones would split apart at the distal aspect just like in the wrist in the hand the image here is not necessarily the typical way that all textbooks will present the ankle in the feet if you look down at your feet you see your toes pointing forward right so oftentimes the books just have them pointing up on the slides but just like in the wrist in the hand sometimes you can mix up your proximal and distal so always make sure you Landmark what view you are in what is superior inferior media lateral Etc while both the tibia and fibula articulate with the talus like in the ankle joints we just talked about the talus is a tarsal and so it's only part of the ankle joint and it is considered a bone in the foot there are seven tarsals all together and all are considered bones of the foot not bones of the ankle so the tarsals that you have are the talus calcaneus navicular the third or lateral cuneiform second or intermediate cuneiform the medial or first uniform and your cuboid and just like in the hand there are several mnemonics that you can use to remember the tarsals you can look up others but the one that I've shown here on the slide is tall centers never take shots from Corners here you have a right foot and you'll notice that it's a superior view medial is on the left and your toes which would be the most distal are on the top you can see the seven tarsals quite clearly and again the tarsals are considered bones of the foot not bones of the ankle what we can see here is our Talus and it's sitting on top and it's the one that's going to join with our tibia and fibula in those ankle joints we have our calcaneus which forms our heel the navicular on the medial side of the foot that's shaped kind of like a boat we have then our medial cuneiform or our first cuneiform on the medial side again but it's articulating with the metatarsal one we have our intermediate cuneiform or our second cuneiform which is going to articulate with our metatarsal number two then we have our lateral cuneiform which is going for third cuneiform which is in the middle kind of the top of your foot there it's going to articulate with metatarsal number three and then we have our cuboid and it's on the lateral side of the foot and it's articulating with metatarsals four and five you can also see the metatarsals and phalanges but we will be dealing with these bones in the next slides in this medial view so looking for medial to lateral it's still of the right foot you are looking at basically the arch of the foot and here again you can see the talus on top the calcaneus on the bottom the boat shaped navicular your medial cuniform or your first uniform as well as that first metatarsal you can see a little bit of the intermediate cuneiform the second cuneiform they're poking out but you really can't seem too much of it you need to have an arch on the medial side of your foot because it helps with weight distribution you do have a little bit of room for flexibility in the foot and that's going to help you with some Force propulsion in the lateral view still a right foot and here you're looking from lateral to medial you can see the talus you can see the calcaneus you can see the navicular still you can see the cuboid really well remember it's very lateral we can still see that intermediate and lateral cuneiforms as well as we can see the metatarsals in in some of our phalanges there moving on to the metatarsals now and back into a superior view remember medial is going to be by our big toe and you can see that a little bit easier here on the X-ray but the metatarsals just like our metacarpals are making up that sort of meat portion of our foot and we number these starting from one to five with the big toe so the big toe side is number one the baby's toe side is number five and if I rephrase the articulation information that I presented from going over the tarsal bones you can see how metatarsal one is going to articulate with the medial cuneiform metatarsal II with the intermediate cuneiform metatarsal three with a lateral cuneiform metatarsals four and five with the cuboid and now moving on to the phalanges of the foot and we're still in that Superior view still looking at our right foot and the foot has a lot of similarities to the hand the names are actually quite similar so you have to say of the foot or of the hand when you're talking about phalanges otherwise you won't get the full Mark your foot phalanges are named in a very similar way to your hand phalanges they're numbered from one to five the digits we start on the big toe side the big toe gets a special name you're called your hallux and it just like your thumb only has two phalanges in it so it has both a proximal and a distal whereas digits two through five have three phalanges so they have distal middle and proximal phalanges in them and remember be careful in this view distal is actually the furthest one down proximal is obviously closer right so watch out for your top to bottom if you you were to name this bone you would have to call it the proximal Phalanx of the second digit of the foot to be very specific so there's no confusion you know what you're talking about you'll get full marks on the test for that and that is the end of module three the skeletal system Part D appendicular skeleton lower thank you