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By the end of this section, you will be able to:
  • Classify bones according to their shapes
  • Describe the function of each category of bones

The 206 bones that compose the adult skeleton are divided into five categories based on their shapes ( [link] ). Their shapes and their functions are related such that each categorical shape of bone has a distinct function.

Classifications of bones

This illustration shows an anterior view of a human skeleton with call outs of five bones. The first call out is the sternum, or breast bone, which lies along the midline of the thorax. The sternum is the bone to which the ribs connect at the front of the body. It is classified as a flat bone and appears somewhat like a tie, with an enlarged upper section and a thin, tapering, lower section. The next callout is the right femur, which is the thigh bone. The inferior end of the femur is broad where it connects to the knee while the superior edge is ball-shaped where it attaches to the hip socket. The femur is an example of a long bone. The next callout is of the patella or kneecap. It is a small, wedge-shaped bone that sits on the anterior side of the knee. The kneecap is an example of a sesamoid bone. The next callout is a dorsal view of the right foot. The lateral, intermediate and medial cuneiform bones are small, square-shaped bones of the top of the foot. These bones lie between the proximal edge of the toe bones and the inferior edge of the shin bones. The lateral cuneiform is proximal to the fourth toe while the medial cuneiform is proximal to the great toe. The intermediate cuneiform lies between the lateral and medial cuneiform. These bones are examples of short bones. The fifth callout shows a superior view of one of the lumbar vertebrae. The vertebra has a kidney-shaped body connected to a triangle of bone that projects above the body of the vertebra. Two spines project off of the triangle at approximately 45 degree angles. The vertebrae are examples of irregular bones.
Bones are classified according to their shape.

Long bones

A long bone    is one that is cylindrical in shape, being longer than it is wide. Keep in mind, however, that the term describes the shape of a bone, not its size. Long bones are found in the arms (humerus, ulna, radius) and legs (femur, tibia, fibula), as well as in the fingers (metacarpals, phalanges) and toes (metatarsals, phalanges). Long bones function as levers; they move when muscles contract.

Short bones

A short bone    is one that is cube-like in shape, being approximately equal in length, width, and thickness. The only short bones in the human skeleton are in the carpals of the wrists and the tarsals of the ankles. Short bones provide stability and support as well as some limited motion.

Flat bones

The term “ flat bone    ” is somewhat of a misnomer because, although a flat bone is typically thin, it is also often curved. Examples include the cranial (skull) bones, the scapulae (shoulder blades), the sternum (breastbone), and the ribs. Flat bones serve as points of attachment for muscles and often protect internal organs.

Irregular bones

An irregular bone    is one that does not have any easily characterized shape and therefore does not fit any other classification. These bones tend to have more complex shapes, like the vertebrae that support the spinal cord and protect it from compressive forces. Many facial bones, particularly the ones containing sinuses, are classified as irregular bones.

Sesamoid bones

A sesamoid bone    is a small, round bone that, as the name suggests, is shaped like a sesame seed. These bones form in tendons (the sheaths of tissue that connect bones to muscles) where a great deal of pressure is generated in a joint. The sesamoid bones protect tendons by helping them overcome compressive forces. Sesamoid bones vary in number and placement from person to person but are typically found in tendons associated with the feet, hands, and knees. The patellae (singular = patella) are the only sesamoid bones found in common with every person. [link] reviews bone classifications with their associated features, functions, and examples.

Bone Classifications
Bone classification Features Function(s) Examples
Long Cylinder-like shape, longer than it is wide Leverage Femur, tibia, fibula, metatarsals, humerus, ulna, radius, metacarpals, phalanges
Short Cube-like shape, approximately equal in length, width, and thickness Provide stability, support, while allowing for some motion Carpals, tarsals
Flat Thin and curved Points of attachment for muscles; protectors of internal organs Sternum, ribs, scapulae, cranial bones
Irregular Complex shape Protect internal organs Vertebrae, facial bones
Sesamoid Small and round; embedded in tendons Protect tendons from compressive forces Patellae

Chapter review

Bones can be classified according to their shapes. Long bones, such as the femur, are longer than they are wide. Short bones, such as the carpals, are approximately equal in length, width, and thickness. Flat bones are thin, but are often curved, such as the ribs. Irregular bones such as those of the face have no characteristic shape. Sesamoid bones, such as the patellae, are small and round, and are located in tendons.

Questions & Answers

differences between channel protein and carrier protein in the plasma membrane?
Kumih Reply
does the parietal pleura attached itself to the ribs
Kumih
The main difference is that solutes simply pass through a protein channel, while solutes bind to protein carriers causing a conformational change in the carrier protein and then allows the solute to pass by.
Carmelo
Besides that, both transporters have the same function which is to allow specific solutes in and out of the cell.
Carmelo
The parietal pleura does come in contact with the ribs.
Carmelo
what structure holds the vertebral column in place?
Holly Reply
the ligarmentum flavium
Kumsah
round cushion pads that sit on the between the vertebrae. The intervertebral disc is made up of strong tissue
Kumih
Alimentary canal tissue type
Noob Reply
it consists the oesophagus ,stomach small intestine, large intestine
Kumih
alimentary canal is a type of tissue that consists of mouth, pharynx, oesophagus, stomach, large intestine, small intestine, rectum, and anus
snr
The alimentary canal consists of 4 tunics, and it has all the main tissue types in the body. 1st tunic: Mucosa (simple columnar epithelia) 2nd tunic: Submucosa (dense irregular conn. tissue) 3rd tunic: Muscularis externa (smooth muscle) 4th tunic: Serosa (simple squamous epithelia).
Carmelo
There is also nervous tissue that are present in the muscularis extrena tunic. In the rectum and anus, the mucosal layer contains non keratinized stratified squamous epithelia.
Carmelo
what is epithelial tissue
snr Reply
epithelial tissue is a line in the outer surface of an organism and blood vessels through out the body and inner surface cavities
Kumih
Epithelial tissue is one of the main tissue types on the body. it's main function is to cover and line outer and inner surfaces of organs. For example your skin is epithelial tissue which lines your outer self. The lining of the mucosal layer in your gastrointestinal tract is epithelial tissue.
Carmelo
epithelial tissue is incredibly diverse in function though. It also synthesize and secrets certain products like saliva, hormones, sweat, sebum and mucus.
Carmelo
It also forms structures such as exocrine and endocrine glands, endothelial, and mesothelial membranes as well.
Carmelo
can someone please explain the process lymphatic system
famuyiwa
There are many different types of epithelial tissue and different functions they perform.
Carmelo
@Famuyiwa, the lymphatic organ system contains lymphatic capillaries, vessels, lymph nodes, lymphoid organs and tissues. The lymphatic system is responsible for maintaing blood pressure, filter lymph (activate the immune system), leukopoeiesis, and break down old RBCs.
Carmelo
thanks alot
famuyiwa
welcome, almost forgot, another important function of the lymphatic system is to transports fats inside chylomicrons to the liver and adipose tissue mainly.
Carmelo
This happens after absorption of fats in the enterocytes have occurred and are moved into the latest vessels that lead into lymphatic vessels.
Carmelo
ok
famuyiwa
lacteal*
Carmelo
What is anatomy
Arko Reply
Structures of anatomy
Arko
anatomy is the study of science that deals with how the parts of a body is being structured
snr
anatomy is the study of organisms and the relationship of it's parts
Kumih
tree diagram of the composition of the blood
Poonam Reply
please you said our external hair is dead n non sensational so we the ladies apply cream to it, does it have a negative effect or not?
Abigail Reply
stupiddihedd
Chisom
epithelial tissue connective tissue muscle tissue nervous tissue
Eliham Reply
....
Ruth
Is this a question.. or a statement!!?
Mel
Jesus love us!
Daniel
thank you I needed that!!! praise the lord
Melissa
praise God!
Sherin
lol. it was joke. i am atheist xd
Daniel
so what?
Sherin
Jesus is the only living God.
Sherin
one who find refuge in him will rest with him.
Sherin
isnt this a page to ask for anatomy questions.. not bible study
Mel
Share Jesus without fear all around the world
Sherin
and anywhere you want.
Sherin
ok bible thumper. my ex a preachers daughter was a closet lesbian who f***ed me more times at church then we did hymns
Mel
y'all are the worst hypocrites in the entire world
Mel
that's what you say... but we are living for the our King Jesus not for the world.
Sherin
your king will not save you
Mel
lady you need common sense not jesus
Mel
he's saves me everyday and I do have many testimonies
Sherin
as long as you repent on sundays. y'all are free to sin the rest of the week. but are biggots towards gays and those with a different mindset.
Mel
don't look at anyone else. please clean yourself first
Sherin
lady you are probably a troll
Mel
if you live according to the commandments in Bible, you get saved by Jesus as well
Sherin
I'm not a troll
Sherin
testimonies your kind will say y'all die in his name but dont know his words...
Mel
I'm sharing his word
Sherin
how... amen thats really shows people god exists
Mel
every word in the Bible is in tip of our tongue
Sherin
we live and die for him
Sherin
i think the same. i am atheist because all religions were made for money and authority. they telling us fake stories and scary us.
Daniel
you may have read the bible and may go to church but didnt deny being a biggot
Mel
Jesus do exist and I have experienced it mam
Sherin
not everyone is for money, Daniel
Sherin
again she wont deny shes a biggot
Mel
there are people who are fake in Christianity. I'm not saying there isn't. but there are people who just live for him because they experienced Jesus more in their lives. I will pray for y'all for him to touch you.
Sherin
let him speak to you in Jesus name!
Sherin
but mostly yes. they could do good things too but working in nonreligious organisations. i dont said everyone is bad.
Daniel
I'm not getting any money for telling this you.
Sherin
lady i have gone to church read the bible. and Quran both have truths but you as a whole as in the church are the worst Hippocrits
Mel
find churches that are small in congregation
Sherin
even if they had good intentions they spread bad theories, for example: creationism.
Daniel
all they do is pray
Mel
but wont do anything else
Mel
id love to meet you to see who im talking to from behind a screen who says Ill pray for someone who NEVER ASKED.
Mel
Quran does have truth because they copied it from the Bible. when was Bible written. Things which are happening now are from Bible. Think...when was Bible written? and things happening now from it... so are you saying there's no truth in it?
Sherin
think? they are not the same
Mel
in Quran, it says they have to make other people Muslim or else they have to kill people for their God. is that correct?
Sherin
there are less biggots again you dont deny that. and such nicer people with open arms
Mel
so you haven't read the Bible clearly.
Sherin
read the New Testament and you will figure it out.
Sherin
youll turn away a gay man and welcome a rapist
Mel
while Buddhists and islamics welcome the gays and turn away the phedos
Mel
so you are basically saying that people who worship Jesus are fake people right?
Sherin
i bet you never read the quran ever
Mel
Christianity welcomes everyone, but Church have been taught people come in.
Sherin
omg.... youll try to save rapist before allowing your own blood (child) to live in your homes who comes out gay. or not wanna be a Republican. or a gun holder
Mel
I haven't read it. But in its all hates
Sherin
but they have to change from it.
Sherin
ever person i met who is like you. has a conceal carry. owns a gun. goes to church is republican and doesnt like any races besides there own....
Mel
obviously after knowing his name, they clearly will get away from all the bad thinga
Sherin
my point you believe the bible but wont educate yourself on other beliefs...
Mel
who said that?
Sherin
now tell me if the other assumptions are wrong
Mel
which church or person said that to you?
Sherin
well you wont deny it? so it has to be true.....
Mel
no church saud it. i came from a mostly white town with plenty of racists gun wearing biggots
Mel
they are completely wrong. You think Allah said anywhere in the Quran that "he's coming back soon
Sherin
What's Gun used for? It's for yours or my protection from others right.
Sherin
it's not like you have to kill innocent people.
Sherin
if you or me kill innocent people what will happen?
Sherin
you or me will go to hell only.
Sherin
if someone try to come and fight with you or me. we will take the gun for our protection.
Sherin
allah is always creating and coming back by new life....
Mel
you as a person has no right to say about the quran till you have read it...
Mel
most of the American people have Gun with them. they go to church, they call God, they worship, they do fellowship etc.. for Jesus
Sherin
but again you dont deny your not a racist biggot
Mel
or welcome gays .....
Mel
religion doesn't mean racist.
Sherin
or dont protect rapist... or were you abused and liked it
Mel
I like everyone.
Sherin
rapist shouldn't be doing that. According to Bible it's sin
Sherin
guns shouldnt be owned by those who are not right mentally or ment for harm. but again police use deadly force everyday
Mel
Why does Christian doesn't fight back when they struggle with others?
Sherin
according to the bible we shouldnt wear mixed fabrics....
Mel
But why does Muslims does it?
Sherin
we shouldnt lay with man
Mel
According to Bible gays are sin as well
Sherin
man shouldnt lay with man excuse me
Mel
actually.. they dont
Mel
if you are married, it's okay to lay with a man. because in the Bible it says after marriage, they are one. not 2 anymore
Sherin
but you wouldnt know that since you never studied or educated yourself
Mel
you watch news?
Sherin
How many news I know about hate from Muslims towards Christianity.
Sherin
again your kind would rather protect a rapist who prays than your own kids who hide in the closet as a gay man or woman
Mel
Gun shots around the world done by Muslims towards Christianity in Churches.
Sherin
oh good lord....here we go i watch more news channels than i bet have in a year
Mel
heaven and hell doesnt exist. when we die we end our existence. TOTALY. there is nothing after death. we have only 1 life so dont waste time to pray something whad dont exist, and do some good for other people. we are here and now. everything on the world depends what we do. any god dont do anything
Daniel
and dont get me going on politics or trump lady
Mel
so you know. in America itself, in an year bow many Gun shot happens because of religious hates.
Sherin
who said I'm a trump supporter.
Sherin
I don't support any politics. I only live for Christ.
Sherin
How do you differentiate Haversian canal and Volkmann canal?
Holly Reply
These are differentiated based on location. Haversian canal are present right in the middle of the osteon. the Volkmann canals are located to the sides of Haversian canal and their blood vessels and nerve fibers invade deep into spongy bone in long bones.
Carmelo
thank you
Holly
What are coronal arteries?
julie
The coronary arteries/veins are the group of arteries and veins that supplies the myocardium of the heart.
Carmelo
What is augment
Safia Reply
I don't know
Taufik
Google works wonders at answering questions..
Mel
make greater or numerous
Kumih
how to identify tissues cells under a microscope
Carla Reply
any advice on how to identify tissue cells under a microscope?
Carla
structural and function of the living part
Parthiban
What is homeostasis
Haji Reply
ability of living organisms to adjust it internal environment to maintain a stable equilibrium
famuyiwa
how to identify tissues cells under a microscope
Carla
what is the anatomy
aamina Reply
anatomy is the branch of science concerned with the bodily structure of humans animals and other living organisms, especially as revealed by dissection and the separation of parts.
Misikir
what are silhouettes
Magret Reply
is dis Medical term?
Preity
yes
Magret
but I don't know what it means
Magret
silhouette outline of a figure. The sharpness of the silhouette is a function of the shape, size and density of the object. This is most marked in radiography. basketball-shaped silhouette the enlarged cardiac outline seen in the dorsal-ventral view of the thorax in a dog with chronic pericardial
Callisto
Homeostasis
Haji
it's the first stage of wound healing that involves vasoconstriction platelet plug formation and blood clotting
famuyiwa
Levels of complexity
julie
sorry that was fast hemostasis
famuyiwa
Kkkk
julie
Anti there is homeostasis and haemostasis
julie
yes , homeostasis is the abiltity of a living organism to adjust it environment to maintain a stable equilibrium
famuyiwa
Thank you Alice, how about Haemostasis?
Christina
hemostasis is the process of regeneration of brown blood vessels to prevent bleeding from occurring. Hemostasis includes vasoconstriction by the tunica media, plalet plug formation to prevent escaping of blood out of the vessel, and blood clotting which Involves the deposit of fibrin into the plug.
Carmelo
broken blood vessels*
Carmelo
is it true, suppose if a person does something wrong like having bad habitat. Is there any connection to the kids that person going to give birth to?
Sherin
That is a very interesting question! Their has been positive correlations in data about specific behaviors occuring between parents and children. For example, alcohol addiction has been shown to be a possible trait of behavior to be passed down to generations by evaluating genes.
Carmelo
Another example is that certain individuals are more prone to mental disorders like severe depression than others based on genetics. However, also keep in mind that the environment in which you are surrounded daily plays a part in developing specific behaviors.
Carmelo
why are postsynaptic ganglionic neurons unmyelinated
Callie Reply
Postganglionic motor neurons are unmyelinated because the lack myelin sheath. The myelin sheath on the peripheral nervous system is composed of Schwann cells wrapped around the axon inside the endoneurium.
Carmelo
they lack*
Carmelo
Postganglionic (and preganglionic) motor neurons belong to the division of the autonomic nervous system. In contrast, the somatic nervous system contains only one long thick myelinated somatic presynaptic motor neuron.
Carmelo

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Source:  OpenStax, Anatomy & Physiology. OpenStax CNX. Feb 04, 2016 Download for free at http://legacy.cnx.org/content/col11496/1.8
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