A&P Skeletal/Muscular system

Axial skeleton

Forms the central, vertical line down the body

Appendicular skeleton

Everything that is attached to the axial skeleton

What are the five functions of the bones?

1) Support the body

2) Protect organs (skull protects the brain)

3) Movement (due to the attachment of muscles)

4) Stores minerals and fats

5) Site of blood cell formation

How many bones does the adult skeleton have?

206

When we are born, we are born with more than 206 bones—what happens to them?

They fuse together

What are the two types of bone/osseous tissue?

Compact bone and spongy bone

Compact bone is what kind of texture, and what does it do?

Hard and compressed, and it does a lot of the “protection” functions

What does spongy bone feel like, what is it also known as, and what does it look like?

Spongy bone is softer, it is also known as cancellous bone, and it has many open spaces that make it look like a sponge

What are the four groups of bone classifications?

Long, short, flat, and irregular

Describe long bones in terms of their length/width

Long bones are generally longer than they are wide

Long bones contain a shaft, which is called what?

Long bones contain ends, which are called what?

Diaphysis and epiphyses

Long bones are good for what function?

Support

Where do compact and spongy bone make up long bones?

The shaft/diaphysis is made up of compact bone, where the ends/epiphyses are made of spongy bone

Long bones make up all the bones of the limbs except which?

Wrist, ankle, and kneecap bones

What are the most common examples of long bones in the body?

Femur, humerus, and radius

Describe flat bones

They are mostly thin, flattened, and usually curved

Describe the sandwich of compact and spongy bone that makes up flat bones

Two thin layers of compact bone sandwich a layer of spongy bone between them

Examples of flat bones in the body

Most bones of the skull, ribs, sternum

Describe the shape of short bones

Usually cube shaped

What type of bone mainly makes up short bones?

Spongy bones

How to remember that short bones are made of the spongy bone?

Short = spongy

What are sesamoid bones and an example of one?

A type of short bone that forms within tendons, i.e. patella

Name examples of short bones

Carpals (wrist bones) and tarsals (ankle bones)

Why is there a category of irregular bones?

These are bones that do not fit into another category and have an irregular shape

Examples of irregular bones

Pelvis and vertebrae

What is the diaphysis composed of

Compact bone

What are the epiphyses composed of

Spongy bone

Periosteum

Outer connective tissue covering of the diaphysis

Endostuem

Inner connective tissue lining the inside of the diaphysis

Where does the blood cell formation occur?

In the epiphyses of long bones

What does articular cartilage cover?

The external surface of the epiphyses

What is articular cartilage made of, and what does it do?

It is made of hyaline cartilage, and it decreases friction at the joint

What is the epiphyseal plate also known as?

Growth plate

What does the epiphyseal plate cause the bone to do?

Causes the bone to grow lengthwise

If a child fractures a bone near the epiphyseal plate, what could happen?

The bone could stop growing

When children start becoming teenagers, what does the growth plate turn into?

The epiphyseal line

Why is the line seen in adults?

Because adults are done growing

What is the purpose of the medullary cavity?

Bone storage (fats, minerals, and marrow)

The medullary cavity stores ____ in kids and ____ in adults

Red bone marrow in kids and yellow bone marrow in adults

Two categories of bone markings

Projections and depressions/cavities

Tubercle

A small, rounded projection

Tuberosity

A large, rounded projection

Trochanter

A very large projection

Fossa

Depression in a bone

What does the microscopic anatomy of spongy bone consist of?

Needlelike, branching frameworks of bone called trabeculae, and open spaces between the trabaculae that contain blood vessels, nerves, and bone marrow

Red bone marrow produces what?

Red blood cells

What are osteocytes?

Mature bone cells

Lacunae

Small cavities that house the osteocytes

Lamellae

The concentric circles of lacunae around the central canal

Central (Haversian) canal

Opening in the center of the osteon that runs lengthwise down the bone

What does the central (Haversian) canal carry?

Blood vessels and nerves

What is an osteon/Haversian system?

The unit of bone that contains the central canal and the lamellae rings around it

Which is the basic, functional structural unit of bone called?

The osteon

Canaliculi

Canals that form a transport system between bone cells to connect them to a nutrient supply

Perforating canals

Canals that run perpendicular to the central canal

Same as the central canal, what do perforating canals carry?

Blood vessels and nerves

The formation of bone is called

Ossification

Ossification mainly happens where, and why?

In the womb, because hyaline cartilage is turning into bone