Full transcript
0:01so we're going to be starting chapter
0:02six chapter six is made up of two parts
0:04a part A and A Part B and this is on
0:06Bones and skeletal tissue so um we all
0:09start off as skeletal cartilage so the
0:11human skeleton initially it's made up
0:13just of cartilage so when you're talking
0:15when you looking at a at a at a fetus uh
0:18and then uh the um a baby an infant
0:22there's cartilage that's present mostly
0:24cartilage as that organism grows as the
0:27the baby grows the cartilage gets
0:29replaced by bone uh now the places that
0:32it's not replaced by by compact bone by
0:35hard bone uh is uh areas that that that
0:38require flexibility that will stay as
0:40cartilage now skeltal cartilage is made
0:42up of Highly resilient molded cartilage
0:45tissue uh that's mostly water and this
0:48water is what gives it its resiliency uh
0:51it doesn't contain any blood vessels or
0:53nerves uh now how this cartilage gets
0:56this nourish nourishment from is from
0:58the perria the paric condum is what
1:02contains blood vessels so nutrients are
1:05able to be delivered to the cartilage
1:07tissue um so what is a parum exactly
1:11it's a layer of dense connective tissue
1:13that surrounds uh the the cartilage and
1:15it acts like a girdle uh it helps the
1:18cartilage uh resist his outward
1:19expansion okay so it it it creates his
1:22boundaries uh cartilage is made up of
1:24condr sites if you guys recall back from
1:26chapter 4 and these are cells that are
1:28are that are encased Within These
1:30cavities that are called the Lun and
1:32then they're they have an extracellular
1:34Matrix that's uh it's jelly like so we
1:38have three types of cartilage in our
1:39body hen elastic and fiber cartilage so
1:42again this is a a bit of a recap from
1:44chapter 4 hen cartilage recall that it
1:47provides support flexibility and
1:49resilience and it's the most abundant
1:51type of cartilage uh it's made up of a
1:53collagen fibers only when we find them
1:55at our joints at our ribs um the our uh
2:00it's what connects the ribs to your
2:01sternum uh it makes up your layings and
2:03also it makes up the tip of your nose
2:05elastic cartilage it's similar to
2:07highlen Cartage but it contains elastic
2:10fibers and uh we find this only in two
2:12places in the body it makes up the epig
2:14latus and it makes up the upper part of
2:16your ear the last type fiber cartilage
2:20it's uh made up of thick collagen fibers
2:23and it offers great ttile strength and
2:26uh it has remember one of the things
2:27that it does is it absorbs uh
2:29compression and shock so we find this at
2:32the Min Sky of our of our knees and also
2:35we find them in between our our
2:37backbones your vertebraes to form the
2:39vertebral
2:40discs so when you look over here uh it's
2:43just showing you that here you have
2:45cartilage in your nose you have
2:46articular cartilage over here over here
2:49as well your costal cartilage um so this
2:52is all highing cartilage over here over
2:55here again over here um it's it's lining
2:59both the this is the head of the femur
3:02and then also the the head of the
3:04humoris um you have them between your
3:06bones over here in your carpal your
3:08wrist bones now let's look at uh fiber
3:11cartilage so fiber cartilage again you
3:14see them over here between your
3:15backbones so they make up the
3:16invertebral discs then also they're
3:19there between the your uh your knee okay
3:22so this part of your knee joint in
3:23addition to that you also have at the
3:25pubic symphysis over here this is a what
3:28uh you know connects the the front part
3:30of your your uh your two hip bones
3:33together elastic cartilage remember what
3:36we said it's only a couple couple places
3:38that we find it and they're showing one
3:39of the places over here uh elastic C
3:42they're showing that you know you'll
3:43have it on uh your uh the the upper part
3:45of your ear over here that's this is
3:47signifying and over here you can see the
3:51larynx uh yeah the larynx over here it's
3:54showing you and when you see uh your
3:56larynx uh as well as your trachea it's
3:59all made of made up of hen cartilage but
4:02the exception is the eplus iglus is made
4:04up of the elastic
4:07cartilage so uh how does cartilage grow
4:11Cal grows in two ways uh appositional
4:14growth and interstitial growth and we're
4:16going to be looking at both of these
4:17things uh in detail so uh in
4:20oppositional growth the Carthage forming
4:22cells uh in the pic condum they secrete
4:24The Matrix against the external face of
4:27the existing cartilage so the new Matrix
4:29in ends up getting laid down on the
4:31surface of the Carthage in interstitial
4:33growth the condr sites within the luin
4:36they divide and they're secreting new
4:37Matrix that expands uh that's expanding
4:40the cartilage from within so the new
4:42Matrix is made within the
4:44cartilage now calcification of cartilage
4:47occurs during normal bone growth in
4:50youth but it can also happen in older in
4:53in an older age also down the line later
4:55down the line this hard the hardened uh
4:58cartilage uh it's it's not the same as
5:00bone it's it's different uh so there are
5:04seven important functions of bone and we
5:07discussed some of these in the chapter 4
5:09so first of all uh bone is there for
5:12support okay uh it's there for your body
5:14it's it's it's supporting uh uh your
5:17some of your soft organs for example
5:19this is they they anchor onto the bones
5:22um it's there for protection so when you
5:24look at the bones it's protecting the
5:26brain it's protecting the spinal cord
5:28and other organs of vital organs like
5:30your lungs and heart it's being
5:32protected by your rib cage uh it also
5:35acts as levers okay for muscles to
5:38attach you and move uh and it's because
5:40of bones and muscles you know some the
5:42muscles start Contracting they pull
5:44these bones and we're able to move uh
5:46mineral and growth factor uh Factor
5:50storage this is
5:53where uh calcium phosphorus and other U
5:58salts are stored in your body it acts as
6:01a storage Reserve so and if you think
6:04about it now these import these minerals
6:06that you find they're very important for
6:08for normal Health uh and also for
6:10example at times of illness when you're
6:13sick when you have a cold or another
6:14infection your body starts breaking down
6:16these uh uh the bones to release these
6:20salts uh so when you think about it you
6:23know when you're sick and you know your
6:25mother or your grandmother told you to
6:28drink chicken soup the reason you're you
6:30know the chicken soup is good for you is
6:32again when you boil the bones when
6:34you're boiling the the chicken you know
6:36it's the bones that that you're boiling
6:38where all the the nutrition is coming
6:40from to help you feel better so uh yes
6:44that's why you Bo boil the bone in the
6:45chickness to release uh the stored uh U
6:48minerals that are found within
6:51it blood cell formation
6:54uh through the process of himat poesis
6:58okay so when you look at himat
7:00is uh blood okay Poes or you know making
7:04producing so uh blood gets produced in
7:08red bone marrow okay so when you look at
7:10bone you're going to find that it's a
7:11you have red bone marrow and yellow bone
7:13marrow uh the yellow bone marrow this is
7:15where uh this fat is stored okay
7:17triglycerides are stored uh the red B
7:20bone marrow this is where uh blood is
7:22produced within the bone uh also uh
7:26hormone production so osteocalcin Secret
7:29by bone B it helps regulate insulin
7:31secretion uh so in insulin SEC secretion
7:35what it does in return is uh it
7:37maintains your blood sugar levels your
7:39glucose levels and
7:42Metabolism now uh in an adult there are
7:46206 uh bones okay that are named in the
7:49adult in 206 bones now can anybody guess
7:52how many bones you find in a
7:56child um if you guessed it uh a child
8:00has a baby when it's born has uh 300
8:03bones in his body 300 and as that baby
8:05grows those bones start to fuse together
8:07until there's ultimately 206 bones left
8:11uh now uh your your your skeletal system
8:15is divided into two groups based on the
8:17location uh we end up getting an axial
8:19skeletal system and appendicular
8:21skeletal system uh axios skeleton again
8:24it's just everything that's on on the
8:26long axis of the excuse me on the long
8:28axis of the body so your skull your uh
8:31your backbones that's called your
8:32vertebral column your and your rib cage
8:34this is part of your uh axial skeleton
8:37everything else and we're talking about
8:39all your limbs and your your hip bones
8:42that's part of your appendicular
8:45skeleton so when you look over here uh
8:48everything that you see that's in this
8:50uh this color over here this dark tan
8:52color uh that's all uh your axial
8:55skeleton so again you have all your
8:56backbones your ribs over here uh your
8:59skull um again this is all part of your
9:04uh and then also your sternum your
9:05breast bone over here that's all part of
9:06your uh axal skeleton everything else
9:09okay your arms your your your clavicles
9:14uh your scapula your hip bones again the
9:17bones that make up your leg these are
9:19all part of your appendicular
9:24skeleton now bones they are classified
9:27according to shapes as well okay so now
9:31uh there's four shapes some bones are
9:33long if the bones are much longer than
9:35they are in in width we call them long
9:38bones so most of your the bones that
9:39make up your limb are limbs are examples
9:42of long bones now short bones uh these
9:45bones uh they're uh Cube shaped bones
9:48okay so the bones that make up your uh
9:50that you find in your wrist and your
9:52ankles these are short bones uh the seso
9:55bone uh seso bones they form within
9:58tendons
9:59uh so example would be the patella this
10:02is a seso bone and they vary in size and
10:05in in number in different individuals
10:07you have idiosyncratic variations uh for
10:10the CMO
10:12bones flat bones flat bones they're thin
10:16they're flat and they could be slightly
10:18curved so examples of flat bones are
10:20sternum uh scapula and uh your ribs and
10:24most of the bones that make up the skull
10:26are also flat bones then we have
10:28irregular bones irregular bones
10:30complicated shapes they don't fit into
10:32any one of the the the catgories that we
10:35pre previously described so your back
10:37bones and your hip bones are example of
10:40irregular
10:41bones so when you look over here this is
10:43a long bone notice that is much much
10:45longer than it is in width so perfect
10:47example of a long bone now when you look
10:49at uh this bone over here this is a
10:52short bone because it's uh it's almost a
10:56cube shaped um the bones in your wrist
10:58they're also examples of short bones
11:01okay remember this is a sismo bone this
11:04example of a sesm bone this a patella or
11:07you know your kneecap um again another
11:10long bone here another long bone long
11:12bone and then you have your irregular
11:13bone and your back bones are irregular
11:16okay they have some really thin
11:17processes also uh at the same time or
11:19flat as you call them uh but then at the
11:21same time you know uh they're not long
11:23either uh so uh again this is called an
11:27irregular it has it does doesn't fall
11:29into any one single one of these
11:31category of the definitions of the uh
11:33the previous uh categories that we
11:35described flat bones uh also these are
11:38just again they're flat they're slightly
11:40curved bones but the the key thing is
11:43that they're flat they're
11:44thin so the bones that make up your
11:46skull is all is another example of of
11:49these flat
11:51bones uh so bones they're an organ
11:54because they contain different types of
11:55tissue okay so by definition again what
11:57did we say uh uh tissue two or more T
12:00different type of tissues and they come
12:02together they form an organ so in the
12:04previous chapter and then skin uh when
12:06you had ep the epithelial tissue and the
12:10the the connective tissue the epithelial
12:12tissue that made up your epidermis and
12:13the connective tissue that made up your
12:14dermis when it came together it Formed
12:17your cutaneous uh membrane okay it made
12:20up your skin uh another term for bones
12:23again that you'll see used
12:24interchangeably is AI so when you see
12:26the word AI Aus it's means pertaining to
12:29Bone so Aus tissue or bone tissue uh is
12:32predominant uh but a bone also has
12:35nervous tissue that you find within it
12:37okay there's cartilage fibrous
12:39connective tissue muscle muscle cells
12:42epithelial cells in the blood vessels uh
12:46that are present also uh within the bone
12:49um so uh there's three levels of
12:51structure that that you can look at when
12:53you're looking at bones there's the
12:55gross level of structure there's a
12:57microscopic and then there's the
13:00chemical so at the gross level we
13:03looking at compact bone and spongy bone
13:05so compact bone this is the dense outer
13:08layer of every bone okay and this is
13:10what looks smooth and is very solid
13:12spongy bone now this is the inner parts
13:15of the bone and it's made mostly not
13:17always but it's the inner part of the
13:20bone um it's made up of Honeycombs of
13:23small Neal likee or or flat pieces of
13:25bone that's called the
13:27tracula the open space spaces between
13:29the tuula they're filled with red or or
13:32yellow bone
13:34marrow now structures of short irregular
13:37and flat bones they made they're made up
13:39of thin plates of spongy bone okay that
13:42we refer to as the the dipolar they're
13:44covered uh and and the ex on the
13:46external on the outside they're covered
13:48by compact bones compact bones they
13:51sandwich between connective tissue
13:52membranes okay uh and then you have this
13:55periosteum that covers the outside of
13:58the compact bone and the endosteum which
14:00covers the inside of the the compact
14:02bone so remember periostium endium Endo
14:06means within per means uh around okay uh
14:10so surrounding covering so this is the
14:12covering that's on the outside of the
14:14bone and this is the inside
14:17covering so bone marrow is scattered
14:20throughout your spongy bone uh there's
14:22no defined marrow Cav cavities highing
14:24cartilage it covers areas of the bone
14:27that's part of a movable joint so whever
14:30bone is about to connect or come into
14:31contact with another bone you're going
14:33to have cartilage over there highing
14:34cartilage at that point uh so again if
14:37you look over here this is the compact
14:40bone okay the hard part and this is the
14:42the spongy bone okay this is the the
14:44soft bone and these holes these are the
14:46the tracula that that you see over here
14:49okay that these parts that you see over
14:52here make up the holes are the tracula
14:54so again you can see over here the
14:56tracula of the spongy bones right over
14:58here
15:01so the structure of a typical long bone
15:04so long bone all long bones they have a
15:06shaft the shaft is called a diaphysis
15:09okay diaphysis now the ends are called
15:12the epiphysis okay and the there's also
15:16a me membranes that are present now the
15:18diaphysis it's a tubular shaft that
15:20forms a long axis of a bone and it's
15:22made up of compact bone that's
15:23surrounded by a central medular cavity
15:25and that that Central cavity or the
15:27central Canal that's F the yellow marrow
15:29uh in adults now the epiphysis these are
15:31the ends of the bones okay uh the ends
15:34of the long bones and they're made up of
15:36a compact bone externally and on the
15:38inside you have spongy bone
15:40internally articular
15:42cartilages they cover uh the the
15:45surfaces of the the these epiphysis at
15:49the ends of these joints now between the
15:50diaphysis and the epiphysis there is uh
15:54what's referred to as an Epal line or uh
15:58it's what left over of an epsal plate so
16:03uh this is where bone was growing there
16:04was cartilage over here between these
16:06two bones as a child grows okay what
16:09happens is the carridge it starts to you
16:12know uh disappear or not disappear but
16:15the cartilage gets replaced by bone
16:18slowly and this is what how bones
16:22grow from uh you know from birth to
16:26adulthood so when you look over here now
16:28this this is the ends of the bones and
16:30at the ends of the bone you have this
16:31articular cartilage okay that you have
16:32here because remember this part of the
16:33bone is going to touch another bone this
16:35part of the bone is also going to touch
16:36another bone you cannot have two bones
16:38touching each other when you have two
16:39bones uh touching each other and they
16:41rub against each other uh both of those
16:43bones are going to get end up getting
16:44worn out and then you know you have to
16:46have surgery and you need to get bone
16:48replacement uh that's essentially what
16:50ends up happening with the knee
16:51replacement surgery um so and arthritis
16:55this is the what ends up
16:57happening lot most the time again if
16:59you're not able to get it treated or you
17:00know um you don't take further
17:03precautions eventually the cartilage
17:05gets worn away and then the bone start
17:06rubbing against each other it's
17:07excruciatingly excruciatingly painful so
17:11again remember the end of the bone is a
17:13the the epithesis now this part is
17:15closer to the trunk so it's the proximal
17:18epiphysis uh now this is the humorus by
17:20the way this is your upper arm bone this
17:22bone right here so this is part that
17:23connects into your shoulder and this is
17:25the part that connects with your lower
17:26arm your forearm so the proximal
17:29epiphysis is up over here and this is
17:31the the distal EP or distal epiphysis
17:35the middle is the the the diaphysis now
17:37notice this is the out the outer bone
17:39okay this is the the compact bone and
17:41this is all the spongy bone right here
17:43this is the EP line right over here FS
17:45line now if you take an x-ray and you
17:48see that uh in an x-ray you can tell if
17:50both of these uh you know this bone is
17:53solid if it's connected then you know
17:55that you this individual is not going to
17:56grow anymore they've reached their limit
17:58and in a child you're not going to see
18:00there's going to be a gap you you'll see
18:01you'll notice because the there's
18:03cartridge there so the when you look at
18:05an x-ray it's going to the the parents
18:07is going to be
18:09different uh so yeah this is the the
18:11medular cavity so this is where you're
18:12going to have yellow bone mirror over
18:14here and remember this inner part is
18:16lined with the endium okay this is where
18:19the endium is found uh the periostium
18:22you're going to find covering okay the
18:23outer part of the bone the compact bone
18:24per oium is over here endium is going to
18:27be found over here within
18:30uh so again this is a close-up that's
18:32showing you this is the compact bone
18:34over here the hard part of the bone uh
18:36the articular cartilage is over here
18:39okay it's lining the the end of this
18:40bone spongy bone you're going to find
18:42inside notice you have the blood vessels
18:44that are penetrating this uh the bone
18:46throughout the tracula uh these the the
18:49spongy
18:52bone now as far as membrane go goes so
18:55the two membranes we discussed earlier
18:56the periostium and endium the per it's
18:59white it's a double layered membrane
19:01that externally covers the surface
19:03except at the joints so uh it's made up
19:06of a fibrous layer and this is the outer
19:08layer that's made up of dense irregular
19:09connective tissue and it's made up of
19:11these Sharpies fibers that secure uh
19:15that secured to the bone matrix then
19:18there's an also an osteogenic layer okay
19:20osteogenic layer and this is the inner
19:22layer that's uh abing the bone and it
19:25contains these osteogenic stem cells
19:28that gives rise to most of all the bone
19:30cells uh so in other words these are the
19:32cells are going to make the bone okay
19:34bone making cells osteogenic stem cells
19:38they produce bone uh
19:40so uh the periostium uh it contains many
19:44nerve fibers and blood vessels that
19:46continue on uh uh to the shaft through
19:49these little holes that we have within
19:51the bones that are called the nutrient
19:52foren now foren they're tiny openings
19:55small holes tiny openings uh it also
19:57provides uh anchoring points for tendons
20:00and ligaments to attach to so you can
20:02see that this is a very important
20:04membrane now the endosteum uh this is
20:07the inner part remember it's a delicate
20:08connected tissue membrane that's
20:10covering the internal bone surface and
20:12it covers the tabula of spongy bones as
20:14well uh It lines the canals that pass
20:17through the compact bone uh so like the
20:19periostium it also contains bone forming
20:22cells these oogenic cells and they uh
20:26these cells they will differentiate
20:28differen to other type of bone
20:32cells so again you can it's the same
20:34thing you're looking at the endosteum
20:36here this is yellow bone marrow over
20:37here this is compact bone uh this is the
20:40periostium and these holes that you see
20:42here this these are the the nutrient
20:44forment that we talked about okay so
20:46these are tiny openings uh and this is a
20:48nutrient
20:49artery now we call it nutrient because
20:52it's it's it's it's nourishing the
20:55bone and over here you can see these uh
20:58these five fibers these are these
20:59Sharpie fibers that we're talking about
21:01that I mentioned previously so
21:04hematopoetic tissue and bones okay
21:06hematop poetic tissue is going to be uh
21:08red bone merrow okay so the red merrow
21:10is found within the tracular cavities of
21:12the spongy bones and the dipoles of flat
21:14bones such as a sternum U so in newborns
21:17the mular cavities and all of the the
21:20spongy bones they contain red bone
21:22marrow in adults red bone marrow it's
21:24found in the uh in the the head of the
21:26femur uh that's your upper that's your
21:29thigh bone uh your uh your upper armb
21:32Bones the humoris and most activities uh
21:36but the most active areas of homat are
21:39found in the flat bones uh at the
21:41dipoles of these flat bones in addition
21:43to some of these irregular bones like
21:45the hip bone uh this is why again when
21:48you when you need to donate a a a bone
21:51marrow and you go to these Don the donor
21:53centers they remove it uh the they
21:56remove the the the the marrow from the
21:58hip bone now yellow marrow it can
22:01convert into red if need be uh so if
22:04when someone becomes anemic for example
22:06the yellow marrow it'll turn into red
22:08red
22:10marrow so your body it has these backup
22:12systems in it now we're going to be
22:14talking about some of the markings that
22:15we find on Bones okay remember this is
22:17all still part of the gross anatomy the
22:19things that you can see observe easily
22:21um so uh these markings are usually
22:25they're usually going to be sites where
22:27muscles come and attached to or or uh uh
22:30not muscles but where you're going to
22:31find muscles that will be attaching to
22:33it by way of the ligaments I'm Sorry by
22:36way of the tendons uh and then also
22:38ligaments will attach over here also you
22:40find markings where ligaments attach now
22:42what's the difference between the two
22:44now ligaments they connect bone to bone
22:47okay ligaments connect bone to bone
22:48tendons they connect a muscle to a bone
22:52okay so do not forget um areas that are
22:55involved in joint formation or conduits
22:57for blood vessels and nerves
22:58also uh some of them are well are named
23:02so you'll see uh markings over there as
23:05well and usually the these uh these
23:07openings uh are named after the uh the
23:11blood vessels that serve
23:13them so uh now three type of markings so
23:17first of all when you look at bones and
23:19there's a like a a big bump coming out
23:22we call that a projection or bulge of
23:24the bone these are projections this may
23:26be due to increased stress from muscle
23:28Pole or is a modification for joints
23:31depressions these are b-shaped or groov
23:33like Cuts U cutouts that acts as
23:36passageways usually for nerves or for
23:38blood vessels to go through or again
23:40they could play a role in joints then we
23:42have the openings now these openings uh
23:45or canals in Bones they serve as
23:47passageways for again for nerves and for
23:49blood vessels to to go
23:51through so let's look at over here first
23:55of all when you see a term a tuberosity
23:57uh tu verocity is uh Again by
23:59description large rounded projections so
24:02when you look over here um uh what do we
24:07have here
24:08uh well this is a
24:11tuberosity okay perfect uh right over
24:14here uh this is actually a tubercle
24:17which is a little bit uh different tubal
24:19are small rounded projections uh on
24:21Bones uh over here is good okay here so
24:24this is a big round so the part of your
24:26your your your um your isum so this is
24:30called the isal tuberosity so it's a
24:32large rounded projection and it could be
24:34rough also so remember the opp the the
24:37opposite of a tuberosity is a tubal
24:39where it's a small rounded projection
24:42okay uh and we looked at a tuberosity
24:45already now then you have something
24:47tranter tranter are very large they're
24:49blunt irregular shape bumps or
24:52projections so right over here on your
24:54your thigh bone you have this this is
24:55called the greater trochanter okay so
24:58it's it's much higher up and it's a big
24:59bump so you call this the greater
25:00there's also a lesser this part is a
25:02lesser Tantra cuz it's a little bit
25:03lower down on this bone uh then there's
25:06lines so
25:08lines uh these are narrow Ridges of
25:10Bones they're less prominent than a
25:12crust now a crust it's a narrow Ridge of
25:15the bone so if you look over here this
25:17is the iliac crust uh and this is part
25:19of your hip bone so the upper border is
25:20called the iliac crust this part of
25:22their bones called the ilium uh epical
25:25these are areas that are uh um that are
25:27on or above a condal so when you look
25:30over here this is the the medial cond
25:32dial so this area above it is the um on
25:36I'm sorry yeah this cond over here this
25:37is the the medial cond over here and
25:40there's also tubal aine above it okay so
25:43it's hard to see in this picture but uh
25:44as you move along and you see close up
25:46to these bones you'll be better able to
25:48to see uh the these uh these different
25:51structures uh including this uh this
25:53Tule here the adductor tubic as well as
25:55the the medial
25:58so remember the where do we go at uh
26:01tranter lines uh tubercle epical epical
26:06and then spine so sign spines they're
26:09sharp they're skinny they're slender uh
26:12pointed edges so when you look at this
26:14backbone uh this is a a spinus process
26:17over over here okay this is the spine of
26:19this of this bone uh also your uh for
26:22example your uh another bone that you're
26:25going to see this is on is your your
26:27scapula or shoulder blade uh and then
26:30Pro a process is just any bony
26:31prominence is called referred to as a
26:33process um so we'll see uh so the spinus
26:37process I'm sorry yeah so this is a bony
26:39process spinus process uh I said that in
26:42incorrectly so spines uh so yeah they're
26:44going to be sharp slender so this spinus
26:48process is not considered to be part of
26:51a spine so
26:53um like I I told you earlier the the
26:57your uh shoulder your um your scapula it
27:00has the spinus process over
27:02there
27:05um so projections that help to form
27:08joints so you have a head so a head uh
27:11is a it's bony expansion carried on a
27:14narrow neck so this is the head okay
27:16it's a bony expansion that's on the neck
27:17of this facet these are smooth nearly
27:21flat surfaces so you look over here this
27:23is very smooth it's almost flat surface
27:25now condal is are round uh rounded
27:28articulation articular projections okay
27:31so if you look over here uh this is your
27:33lower jaw bone then the your upper jaw
27:35bone both of these they come together uh
27:38to form this uh very smooth joint so
27:40it's a round articular this is round
27:42articular projection they tend to be
27:44small now Ramis that's a bar of bone
27:48it's an arm likee bar of a bone so if
27:50you look over here this is the Ramis of
27:52your
27:53jaw now grooves are furrows okay a
27:57Groove is just a
27:59uh a fissure is a narrow slitlike
28:02opening okay and a forment that's a
28:05round oval opening that's through a bone
28:08okay that's a a foramen a notch is an
28:11indentation at the edge of of a
28:13structure that's a notch an indentation
28:15at the edge of a structure so you see a
28:18notch over here uh Aus that's a canal
28:22okay a canal like passageway so your ear
28:26for example right over here that's a me
28:30uh then you have sinus so sinus is a
28:32cavity within a bone okay it's filled
28:34with air and lined with a mucus membrane
28:36so here this is a a sinus over
28:41here and the FASA okay it's a shallow
28:45it's a basin like depression in a bone
28:47okay it usually serves as a an articular
28:50surface a FAA there's a fossil over
28:53there and again we'll see things in
28:56details much closer up it's harder to
28:57look at
28:58but this is just take the try to
29:00understand the definition at this point
29:02U so cells of bone tissue now bone
29:06tissue bones are made up of five major
29:08types of
29:09cells now each one is specialized form
29:12of the same basic cells type so you have
29:14osteogenic cells osteoblast osteocytes
29:18bone lining cells and
29:20osteoclast for osteogenic cells these
29:23are also called ostop progenerate cells
29:26and these are highly might mitotically
29:29active stem cells that we find within
29:30the periostium and the endosteum um when
29:33these cells are stimulated they
29:35differentiate into an osteoblast or a
29:38bone lining cell uh some of them then
29:40remain as osteogenic stem cells now now
29:43Osteo
29:45blast these are bone building cells and
29:48they secrete this UNM mineralized uh
29:50bone matrix that's called an osteoid and
29:53these osteoids are made up of collagen
29:55and calcium binding proteins the C it
29:58ends up making up 90% of the bones the
30:01bones
30:03tissue the protein uh osteoblast these
30:07are actively mtic also they're very um
30:11mtic
30:13cells so when you look over here this is
30:15an osteogenic stem cell this stem cell
30:18can turn into one of these guys which is
30:19an osteoblast okay and it what is this
30:22it's a matrix synthesizing cell that's
30:24responsible for your bone to grow the
30:27Osteo side these are mature bone cells
30:29that we find within the Lun that uh that
30:32do not divide anymore okay so they kind
30:35of reached you know the end of their
30:37reproduction uh time in their life cycle
30:41and they maintain the bone matrix and
30:43they act as stress or strain sensors so
30:46they respond to Mechanical stimuli such
30:48as an increase in force or or bone on
30:52on an increas in force on bone or
30:56weightlessness the unate information to
30:59the osteoblast and as well as osteoclast
31:02osteoclast these are bone breaking cells
31:05so and these are very important for
31:07bones to rebuild themselves or bones for
31:09remodeling themselves so uh again
31:12remember once these we'll talk about it
31:14later but um remodeling need to is
31:16constantly occurring as well okay just
31:18like buildings for example you know you
31:19take a a building and after it's built
31:23you can't just walk away from it if you
31:24end up doing no maintenance at it you
31:25know if you don't keep going and
31:26primarying it and uh painting it and
31:29maybe doing some tuck pointing
31:31eventually that whole thing is going to
31:32become weak and you know at it's going
31:34to break down
31:36prematurely uh also there's bone lining
31:38cells now bone lining cells these are
31:40flat cells that you have on the the bone
31:42surface that are believed uh to to help
31:45maintain the Matrix along with the
31:48osteocytes so again they're F on the
31:50external bone surface uh the lining uh
31:53lining cells are called the periostal
31:56cells
31:58on the internal surface they are called
32:00the Endo uh the industrial cells all
32:03right so remember uh the bone lining
32:05cells depending on where they're they're
32:07found they're either called periostal
32:09cells or endal cells if they're found
32:11within uh the they're found in the
32:14internal surface and oal cells if they
32:16found on the external surface they're
32:18periostal cells the Osteo class okay now
32:22these are bone breaking cells they're
32:25derived from the same hematopoetic stem
32:27cells became the monocytes and macroasia
32:30um they're giant multinucleated cells
32:33that function in bone breaking okay or
32:36another term that we use for that is uh
32:38resorption okay bone resorption uh when
32:41these cells are active the cells that
32:43are located in the depressions are
32:44called uh uh resorption
32:49base now these cells they have they the
32:53cells they have these ruffled borders
32:55that serve to increase the surface area
32:57for enzymes to to to to start degrading
33:00uh the bones also they help steal off
33:02areas from the surrounding Matrix so
33:05these are very extremely important
33:08cells so this is an osteocytes this is a
33:10mature bone cell and this monitors and
33:13maintains uh the the bone matrix now
33:16these OC class these are the bone
33:18breaking cells also again notice in
33:20structure they look very different they
33:22kind of somewhat they resemble these
33:23white blood cells uh but again notice
33:26that these are multinuclear
33:28uh uh
33:31cells when you look at over here these
33:34are uni nucleates right there's just one
33:36nucleus so again if you see a picture on
33:38an exam or a question so keep in mind
33:40the only cell that's multinucleated when
33:42it comes to the bones are going to be
33:44these bone resorbing Osteo
33:46class now compact bone another term for
33:49compact bone is Lamar bone and it's made
33:52it's made of Lamar bone consists of this
33:55of a herion system okay these are these
33:57individual uh uh bone cell units called
34:00the oon they also have canals and uh uh
34:03canaliculi in addition to that there's
34:06this inter interstitial and circum
34:09circumferential
34:10Lamay that they're made up of now the
34:13conversion systems also called uh which
34:15is an tion so this is an tion is a
34:20structural unit of the compact bone uh
34:23it's made up of these uh these elongated
34:26uh cylinders that run parallel to the
34:28long axis of the bones and they act as
34:30Tiny weightbearing pillars now
34:33tion an osteon cylinder it's made up of
34:36several rings of bone matrix that's
34:37called the Lamay the lamas they contain
34:40the collagen fibers that run in
34:41different directions to the AJ in the
34:44these adjacent Rings uh they're able to
34:46withstand stress and they they're able
34:48to resist twisting as well now bone
34:51salts are found between these collagen
34:54fibers so when you look over here these
34:56are these collagen fibers
34:58right that you see and notice again that
35:00directions they're running in opposite
35:02in different directions it's not the
35:03same so again uh also then uh uh you
35:08within the the central Canal okay this
35:10is it's it's a canal it's an opening you
35:12have the the blood vessels and the
35:13nerves that are uh running through
35:15through this through them so again this
35:18is what a single oion is is made up
35:23of now canals and cani uh so um the
35:28central Canal or this heran canal it
35:30runs through the core of this osteon and
35:32this is where we in the previous slide
35:34we saw the blood vessels and nerve
35:35endings coming out from there's also
35:37these Perforating vman or they're also
35:40called vman canals uh so the vman's
35:43canals perfering canals
35:46uh these canals they're lined with osum
35:50that occurs at right angles to the
35:51central
35:53Canal so um Lain these are small
35:57cavities that contain the
35:59osteocytes uh the canalize these are
36:02hairlike canals that connect the Lin to
36:05one another and to the central Canal
36:07osteoblast a secrete bone matrix they
36:09maintain contact with one another and
36:11the osteocytes Via uh cell projections
36:14with gap Junctions now when Matrix
36:16hardens uh and the cells are trapped uh
36:21can can are are
36:24formed now what this does is it allows
36:27for communication between the oio sites
36:29of the oeans and permit nutrients and
36:32waste to be relayed from one cell to
36:34another cell so again this is very
36:35important it this is like the
36:37transportation system on the the the
36:39infrastructure of how things are able to
36:41move
36:43about now interstitial and
36:45circumferential Lamay now the
36:48interstitial Lamay these are Lamay that
36:50are not part of the osteons some fill
36:53gaps between uh forming osteons While
36:56others uh they REM remnants of oans cut
37:01by bone remodeling now the
37:03circumferential Lamay uh just deep to
37:06the per oium but they're superficial to
37:09the end oium uh this is where they're
37:12found these layers of laminate they
37:15extend around the entire surface of the
37:17diaphysis uh and they help long bones
37:20resist
37:23twisting okay so in this picture here
37:25we're going to try to connect the dots
37:26of everything that we learned learned
37:27about okay in terms of structure so we
37:29can find these things so again what are
37:31we looking at we're looking at a
37:32cross-section of a long bone over here
37:35so this is the the compact bone the hard
37:38part of the bone okay the outer part the
37:40hard part of the bone and this is the
37:41spongy bone okay the inner soft part of
37:43the bone this is where you have the the
37:46the tracula that are found this is made
37:48of of compact bone all right or in other
37:50words this has the the oans you're going
37:52to find over here so when you're looking
37:54at the uh the the let before we get to
37:56that um let's look at these so in Aon
38:01it's made up of a herv verion system
38:02right and so this is a herv verion
38:05system here look at all these Rings okay
38:06they all form a single tion this is
38:09another one one two three so and then
38:11you have the central Canal so this is
38:13another this is an aeon this is another
38:15oon over here uh from here to here is
38:18another oon over here so these are all
38:20these are all oans and or herion systems
38:24now within this oion you have you have
38:26these canal so this is this this this
38:28cavity that's the herion canal or the
38:31central canal and this is what we're
38:32looking at over here this is the central
38:34canal and within the central Canal you
38:36have the blood vessels that are running
38:37through you have your
38:39artery a vein as well as a nerve that
38:42run through now these are running long
38:45way okay they're running longitudinally
38:48now coming off at at a 90° angles off of
38:52this long uh Central this longitudinal
38:55Central Canal or subversion canal Canal
38:58you have uh these uh Perforating canals
39:00or these vman canals so these guys they
39:02come off and they you know they Farm
39:05like the cross so think of this as like
39:06a
39:08major uh think of this as like a
39:12Lakeshore Drive okay or you know a major
39:14Expressway and think of these as the
39:16exit points or the the entrance points
39:18or the exit points off the expressway
39:20okay for things to to to come off and to
39:22come back in uh in from um so this is
39:26what these B canals do now let's start
39:30taking a closer look at this all right
39:32now these individual Rings remember what
39:34did we say these are called the Lamay
39:36right or the the the the
39:38Lamela now uh collectively so when you
39:42look over here uh here here here here
39:46are all these Lamela over here
39:47okay right we got one two three four
39:50layers of that and then uh after that we
39:53have this inner part uh remember what we
39:56call this this is a central Canal now
39:59coming off of that when you look over
40:00here these are the bone cells the oeans
40:03and remember what we said about the
40:04oeans the oeans they lie within cavities
40:06and what do you call those cavities
40:07they're called the launa okay so the
40:09Luna are the cavities that hold the
40:11oeans now what connects one cavity to
40:14another cavity are these uh uh the
40:18canaliculi okay or the the the canul
40:21yeah so Luna are the cavities that hold
40:24the osteons and then what connects one
40:27uh uh laa to another laa are these
40:31canals okay or the canal canaliculi
40:34that's how I remember it uh so these
40:37they connect one another the canul and
40:39these are these lines that you see over
40:41here
40:42okay um and then again notice this is
40:46you have your your periostium over here
40:48and you can see these Sharpie fi fibers
40:50then also you see the the perial blood
40:53vessels uh I think that's just about it
40:55that you can see clearly over here that
40:56that we covered over in the the two
40:58things now the intertial lamula and the
41:01the the circumferential circumferential
41:04uh they're not I don't think they're
41:06showing oh yeah actually they are so
41:07it's again it's very hard to see they
41:09don't have a good closeup of it but this
41:12area would be the circumferential lamula
41:14and then over here uh this would be the
41:17the the intertial lamula again it's very
41:19difficult to see because these are not
41:20ideal optimal drawings to show these two
41:22structures they did a pretty good job
41:24with other ones but not for these
41:28uh so now we're going to be talking
41:29about spongy bone so spongy bone it
41:31appears poorly organized but it's
41:33actually organized along lines of stress
41:36and this helps the bone resist uh stress
41:39the tracula uh they're think of them as
41:43like cables on a bridge and they help
41:46strengthen the bone they make it much
41:47much much stronger uh no we don't have
41:50any oans that are present in spongy bone
41:52but the tcul they do contain irregular
41:55arranged Lamay and osteoid that are
41:57interconnected by these
41:59canaliculi uh capillar in the andium
42:01they're what's supplying the nutrients
42:04to the tracula so when you look over
42:06here there we go you got spongy bone
42:08here you got the compact bone and then
42:10you have this tracula of this the spongy
42:13bone um so bone is made up of both
42:16organic and inorganic components now the
42:19organic components of bones are they
42:22include the oogenic cells the osteoblast
42:24ocytes OC class ooids and the bone
42:26lining cells
42:27now osteoids this makes up about
42:30onethird of the organic bone matrix
42:32these are secreted by the osteoblast and
42:35it's made up of a ground substance of
42:36collagen fibers and this collagen fibers
42:38it contributes to the high tensile
42:41strengths and the flexibility of a
42:45bone the resilience of bone is due to
42:48the the the the sacrificial Bonds in or
42:51between the cagen molecules that stretch
42:53and they break to dissipate the energy
42:55and to prevent uh fractures fromr
42:58if there's no additional trauma the
42:59bonds they reform now we're going to be
43:02talking about the inorganic components
43:04the inorganic components that we have
43:06are the hydroxy appetites and these are
43:08the mineral salts they make up 65% of
43:11the bone mass that's quite significant
43:13uh it's uh consists mainly of tiny
43:16calcium phosphates uh um uh in a that
43:20are in and around collagen fibers and uh
43:23also the hydroxy appetite is responsible
43:25for uh what Harden the bone and makes it
43:28resistance to to
43:32compression bone is half a strong as
43:35Steel in resisting compression but it's
43:38strong as strong as Steel in resisting
43:40tension
43:43uh it lasts long after death okay
43:46because of the mineral composition so
43:48even after you die for many years and
43:50years and years you will find bone that
43:52you can find intact uh bone also reveals
43:56a lot of information about ancient
43:58people like what their diet was what
44:00type of Life they lived um what type of
44:03disease they may have suffered from um
44:05again their age at at at the at death uh
44:08there's so many things you can find out
44:10uh when you look at bone tissue uh when
44:13we move if you guys take another course
44:15in anthropology you can learn more about
44:18uh you can study this more and then you
44:19know you learn about these things um
44:22this is it for the first part of the
44:25this chapter uh please leave any
44:27questions any comments Down Below in the
44:30comments below if you like it please
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44:34you so much for watching