Skeletal System

The second hardest substance in the body

Bone

It is very good at being able to repair itself after an injury.

True

The cells that produce bone

Osteoblasts

What do osteoblasts secrete?

The matrix of the bone

The osteoblast hardens the matrix through a process called

Ossification

Once the ossification process has taken place, the osteoblasts are then called

Osteocytes

Osteocytes are the cells that

Maintain bone tissue

The most basic function of the skeletal system

Support

The firm strength of the bones does what?

Protects the delicate organs and tissue by either completely or partially surrounding them.

Bones act as _____ for the skeletal muscles.

Levers

The skeletal muscles are attached to bones by

Tendons

They are _____ _____ for minerals like calcium

Storage Sites

The body is able to deposit and withdraw calcium when needed

to control the level in the blood

Some of the bones are sites for

blood cell formation

Blood cell formation is called what?

hematopoesis

Where does hematopoesis occur?

In bone marrow

The outer surfaces of the bone are covered with a membrane called the what?

Periosteum

Where is the periosteum not found?

The joint (articular) surfaces of bones

The inner layer of the periosteum contains what?

Contains osteoblasts

What is the inner layer of the periosteum involved in?

The healing of fractures

The outer layer of the periosteum is composed of what?

Fibrous tissue

It is sometimes called spongy bone because it has the appearance of a sponge

Cancellous Bone

The spaces between the bone are filled with

Marrow

Cancellous bone is light, but very strong

True

This bone is very dense, heavy, and strong

Compact Bone

What type of bone is found in the shafts of long bones, and in the outer layer of how many bones?

Compact bon is found in ALL bones

Osteogenic cell

Develops into an osteoblast

Osteoblast

Forms into a bone matrix

Osteocyte

Maintains bone tissue

Osteoclast

Functions in resorption, the breakdown of bone matrix

As the long bone grows what ossifies near the diaphysis and epiphyses?

The metaphysis which contains the growth plate

Where does the blood supply come from?

Tiny blood vessels that penetrate the periosteum

Once through the periosteum, where do they pass through?

Channels in the bone matrix called Volkmann’s Canals

Volkmann Canals join to blood vessels in what canal that bring nutrients to osteocytes?

Haversian Canals

Large blood vessels, lymph vessels, and nerves enter many of the larger bones through large holes called …..

Nutrient Foramina

What does the nutrient foramina primarily do?

Carries blood in and out of the bone marrow

What do nutrient foraminas look like on radiographs?

A crack-type fracture

Osteoblasts are cells that form what?

Bone

Osteoblasts secrete what and then supply what to harden it?

Matrix of bone and minerals

Osteocytes have the ability to what?

Revert back into osteoblasts and form new bone if an injury occurs

Osteocytes’ function is debatable, but it thought that they what?

Maintain the bone tissue

Osteoclasts are responsible for what?

Breaking down bone?

What does it mean when osetoclasts break down bone?

They remove bone from where it is not needed

Osteoclasts are needed for what?

For bone remodeling to take place

Osteoclasts allow what to be withdrawn from the bone when the levels in the blood drop too low?

Calcium

Most bones in the body develop by this method

Endochondral Bone Formation

In endochondral bone formation the body lays down a what that is gradually replaced by bone?

Cartilage template

In endochondral bone formation the long bones (femur) start developing in the what of the cartilage?

Diaphysis (the shaft)

The diaphysis is also know as what in endochondral bone formation?

The primary growth center

The what of the bone are the secondary growth centers in endochondral bone formation?

The epiphysis (ends)

Epiphyseal plates are what in endochondral bone formation?

The two areas of the bone where cartilage remains in long bons when an animal is born.

Where are the epiphyseal plates located?

Between the diaphysis and the epiphysis

The epiphyseal plates allow what to happen for endochondral bone formation?

Long bones to lengthen as the animal grows

Intramembranous bone formation one happens where?

In certain bones of the skull

In intramembranous bone formation the process creates what?

The flat bones of the cranium (skull) that surround the brain

In intramembranous bone formation it occurs in what?

Primitive connective tissues (collagen fibrils)

Red marrow is what kind of tissue?

Hematopoietic tissue

What does hematopoietic tissue do?

Forms red blood cells

What makes up the majority of the marrow in young animals, but there is only a small amount present in older animals?

Red marrow

Red marrow can be found in older animals but only in specific sites. What sites?

Ends of some long bones, interiors of the pelvic bones, and the sternum

Yellow bone marrow consists of mainly what?

Adipose tissue

This kind of marrow is most common in adults

Yellow Bone Marrow

Yellow marrow does not produce red blood cells but has the ability to do what?

Revert back to red marrow if the body needs extra

Skull, hyoid bone, spinal column, ribs , and sternum are all bones of the what?

Axial Skeleton

All bones of the axial skeleton lie on or near the what?

Median plane of the body

What is the most complex part of the skeleton?

The skull

How many bones does the skull consist of?

37-38

In the skull most of the bones are united by what?

Sutures

What are sutures?

Immovable joints, fibrous joints

What is the only movable joint connected to the skull called?

The mandible

Yellow

Frontal Bone

Green

Parietal Bone

Blue

Occipital Bone

Purple

Temporal Bone

There are two, located below the parietal bones

Temporal Bones

Temporal bones form the what walls of the skull?

Lateral

The temporal bones house what structures?

The middle and inner ear

“Forehead” region of the skull

Frontal bone

The frontal bone forms the front part of the skull and a portion of the….

Eye socket (orbit)

What sinuses are contained in the frontal bone?

Paranasal and frontal

Incisive bones

House the upper incisors

Nasal bones

Form the bridge of the nose

Maxillary bones

Make up most of the upper jaw

Lacrimal bones

Form the medial part of the orbit, and have a small space that houses part of the tear drainage system of the eye

Zygomatic bones

Form the zygomatic arches

Mandible

The lower jaw, and the only moveable skull bone, joined by a cartilage joint (mandibular symphysis)

Shaft of the mandible

Houses all the teeth

Ramus

Where the jaw muscles attach and the articular condyles are located

Blue

Ramus

Red

Mandibular Body/Shaft

Red

Incisive

Blue

Nasal

Yellow

Maxillary

Purple

Lacrimal

Green

Zygomatic

Palatine Bone

Makes up the caudal portion of the hard palate

Pterygoid bone

2 small bones that support part of the lateral walls of the throat

Vomer bones

Forms part of the nasal septum

Turbinates

Scroll like bones that fill the nasal cavity

Blue

Palatine