Types of Bones

0:00hi everybody dr mike here in this video

0:02i want to introduce to you

0:03the skeletal system

0:07[Music]

0:14now the skeletal system is a collection

0:16of 206 bones at least in the adult

0:18they play really important roles when it

0:20comes to protection

0:22storage and support now how do bones

0:25play all these important roles well when

0:27it comes to protection for example it

0:29protects underlying structures

0:30or organs when it comes to support it's

0:33going to be supporting the weight of the

0:34body

0:35and also the muscles that are attached

0:36to it to allow for us to move and it

0:39plays an important role

0:40for storage because it's storing

0:42important minerals like calcium

0:44and phosphate so when we look at the

0:46skeletal system you can divide it into a

0:48number of different ways and you can

0:49categorize the bones

0:51a number of different ways as well so

0:52i'm going to show you these different

0:53ways of categorizing

0:55bones first way is dividing the skeletal

0:58system into what we call the axial

1:00skeleton and the appendicular skeleton

1:02so i've drawn up my little skeleton here

1:04and you can see i've highlighted

1:05different colors

1:06all those bones in black are the axial

1:08skeleton it's basically going to be

1:10the skull the rib cage the sternum and

1:13the vertebral column

1:14and the appendicular skeleton is

1:16everything else basically everything

1:17that holds

1:18and moves the limbs or the limbs

1:20themselves i should say so

1:21if we want to be more specific 206 bones

1:25for this whole skeleton

1:26how many bones in the axial skeleton

1:28well what we can do is

1:30we can say that if the axial skeleton is

1:32made up of the

1:33skull and made up of the

1:37hyoid made up of the

1:40vertebrae made up of something called

1:44when we look at it it's called the

1:46ossicles of the middle ear

1:50ossicles of the middle ear it's made up

1:52of the sternum

1:56and rib cage

1:59now how many bones associated with each

2:01of these when we look at the skull

2:02there's 22

2:04bones the hyoid one bone the vertebrae

2:0726 bones

2:09the ossicles six bones the sternum one

2:12bone

2:12and the rib cage we have 24 bones now if

2:17you were to add them

2:18up what you're hopefully going to find

2:20is that this equals to 80 bones 80 bones

2:23of the axial skeleton

2:24so that leaves us 126 bones

2:27for the appendicular skeleton

2:31so what bones are part of the

2:32appendicular skeleton well it's

2:34basically

2:34basically going to be the shoulder

2:36girdle

2:39the arms the hands

2:44the pelvic girdle

2:48the legs

2:52and the feet now how many bones

2:54associated with each of these

2:56well when we look at the shoulder it's

2:57going to be or the shoulder girdle

2:59it's going to be four bones when we look

3:01at the arms it's going to be

3:03six bones when we look at the hands it's

3:0554 bones a lot of bones for the hands

3:07and wrists

3:08the pelvis six bones the legs what we're

3:11going to have a look at is that there's

3:12eight bones for the legs

3:13don't forget the patella and feet

3:15there's going to be 52 bones

3:18now hopefully if we were to add these up

3:20it's going to equal 126

3:22bones that is one way of dividing the

3:25bones up into actual and appendicular

3:27but there's other ways we can have a

3:29look at bones and divide them up or

3:31classify them in accordance to their

3:33shape so what type of shapes do we have

3:36in regards to

3:37bones well a couple of things couple of

3:39ways we can do it first of which

3:40is you can have a look at what we call

3:42flat bones so the skull is an example of

3:45a flat bone

3:47let's write flat bone

3:50like i said the skull and the sternum

3:53they're really good examples of flat

3:54bones what do they do well

3:56flat bones protect underlying structures

3:58or organs

3:59what are the types of bones as long

4:01bones

4:03these are bones that are longer than

4:05they are wider unsurprisingly

4:07that includes the humerus and the tibia

4:10the humerus the radius the ulna the

4:12femur the tibia the fibula for example

4:14there are long bones

4:15and what do they do they provide support

4:18support

4:18and mobility so movement and like i said

4:21an example of this is the

4:23humerus there's also

4:27irregular bones that's another type

4:33and a regular bone are bones that don't

4:35really fit into any other

4:37category and they're strange in shape so

4:39because they're all different in their

4:41shape they're all different in their

4:42function

4:42so an example of this can be the

4:44vertebrae

4:50other types include short bones

4:55now these are bones that are pretty much

4:57as wide as they are long and

4:59usually includes the bones of the wrist

5:01so the carpals

5:02and the ankle and feet the tarsals and

5:05so

5:06i'll write carpals here

5:10and their important role is that there's

5:11many of them first of all

5:13and they have a lot of articulating

5:15surfaces because they've got this

5:17square shape they're going to have

5:18articulation so one bone talking to

5:20another bone here and here and here

5:22and here and what this does is it

5:24provides stability within that

5:26particular joint or

5:27region and the last type is sesamoid

5:31bones and sesamoid bones include that of

5:35the patella or kneecap

5:36and what they do so we'll write that

5:38down patella

5:41and what they do is they have tendons

5:43embedded in them

5:44really important so you can classify

5:47bones according to

5:48shape but again it's not the only way we

5:51can classify

5:52bones the last way i want to tell you is

5:53we can classify bones

5:55according to also their microscopic

5:58anatomy and this is where we're moving

6:00on to this image over here

6:02you can break this this type of bone up

6:04into what we call

6:06cortical bone

6:09and what we call trabecular bone

6:15which is also known as cankalous bone

6:20which is also known as spongy bone

6:26a lot of wonderful different names so

6:28you've got cortical bone

6:29you've got trapecular bone so i've cut

6:32into a bone here and you can see that

6:34on the most outer surface of that bone

6:36you've got

6:37really tightly packed condensed bone

6:40that's that cortical bone

6:41and you can see the cortical bone is

6:43made up of these will look like

6:44circles here and these circles as an

6:47entire unit

6:49are called osteons

6:53importantly the osteons are made up of

6:54all these concentric rings like a tree

6:57these rings are called lamella which

6:59means plate

7:03so you've got multiple lamella packed on

7:05top of each other and then right in the

7:06middle

7:07you've got this little central canal and

7:09this central canal

7:10contains blood vessels and nerve fibers

7:13really important when it comes to being

7:14able to feed that bone tissue

7:17that's cortical bone you can see over

7:20here we've got

7:21trabecular bone or spongy bone or

7:22cancerous bone it's

7:24they don't have osteons that's an

7:25important difference which means that

7:27central canal which is also called the

7:29haversian canal that contains the blood

7:31vessels

7:32they don't have that so the blood

7:33vessels are basically interwoven between

7:35and it diffuses out nutrients to be able

7:38to feed the cells and tissue

7:39underlying trabecular bone how do we

7:42make

7:43bone is the next question well we make

7:45bone by a number of different cell

7:47types bone is connective tissue really

7:50important

7:51and so because bone is connective tissue

7:56it's made up of cells gels and fibers

8:00let's write that down it's connective

8:02tissue it's made up of cells

8:04gels and fibers

8:08and it's the cells that are important

8:10because they lay down the gels and

8:11fibers and produce them what are the

8:13cell types all right

8:14first is there's what we call osteo

8:18progenitor cells

8:24then we've got osteoblasts

8:29osteocytes

8:35osteoclasts

8:38all right first thing the prefix the

8:40start of the word osteo

8:41osteo osteo osteo it all means bone

8:44sight

8:45means cell blast this is how i think

8:48about it blast think about the b

8:49in blast for build this is what builds

8:52bone

8:53think of the c in clasts for crush it

8:56breaks bone

8:57down because bone is constantly being

8:59rebuilt throughout your entire life

9:01you bounce up and down do exercise and

9:03move you want to build bone

9:04if you sit there and don't use it or go

9:06up into the international space station

9:08for example

9:08it breaks it down crushes it progenitor

9:12progenitor to be able to produce

9:13offspring these are stem cells

9:18and so what basically happens is

9:21osteoprogenitor cells will turn into

9:23osteoblasts

9:24osteoblasts are the builders of bone so

9:26these are cells that lay down

9:28the gels and fibers just like a builder

9:30would laying down bricks

9:32and mortar bricks and mortar or concrete

9:34and what it does is it builds bone

9:36around it

9:36and then what happens is the osteoblast

9:38gets stuck in this bone that it's built

9:41and it matures and the osteoblast

9:43matures into something called an

9:44osteocyte

9:45that's the mature osteoblast and they

9:47just stand there

9:48like a mature person would do and just

9:51watch and make sure everything's okay if

9:53there's any problems

9:54it will call in more osteoblasts or if

9:56it needs to break things down

9:57it will call in osteoclasts osteoclasts

10:00are a different cell lineage from these

10:01others

10:02and they eat bone and release all that

10:05calcium and phosphate for example

10:07so what we have gone through is a quick

10:09run through an introduction to the

10:10skeletal system