A&P exam BONES

Parts of the skeletal system

bones, joints, cartilages, ligaments

two subdivision of skeleton

axial skeleton and appendicular skeleton

Functions of the skeletal system

-Support the body

-protect soft organs

-allow movement due to attached skeletal muscle

-stores minerals and fats

-blood cell formation

Compact/Cortical Bone

Surrounds a hollow area inside the diaphysis known as the medullary cavity, which holds yellow bone marrow.

Spongy/Trabecular/Cancellous Bone

Layer of bone tissue having many small spaces and found just inside the layer of compact bone.

Long bones

-longer than they are wide

-have a shaft with heads on both ends

-contain mostly compact bones

Examples of long bone

femur, humerus

Short Bones

-cubed shaped bone

-contain mostly spongy bone

Example of Short bone

carpals and tarsals

Irregular bones

-irregular shape

-do not fit into other bone classification categories

Example of irregular bones

vertebrae and hip bones

Diaphysis

shaft of a long bone

Epiphysis

-End of a long bone

-made up of mostly spongy bone

Periosteum

-outside covering of the diaphysis

-fibrous connective tissue membrane

Sharpey's fibers

secure periosteum to underlying bone

Arteries

Supply long bone with nutrients

articular cartilage

-Covers the external surface of the epiphyses

-Made of hyaline cartilage

-Decreases friction at joint surfaces

Epiphyseal Plate

flat plate of hyaline cartilage seen in young, growing bone

Epiphyseal line

remnant of the epiphyseal plate, seen in adult bones

What is the medullary cavity?

Cavity inside of the shaft of a bone.

What type of marrow does the medullary cavity contain in adults?

Yellow marrow (mostly fat).

What type of marrow does the medullary cavity contain in infants?

Red marrow (for blood cell formation).

Bone markings

-surface features of bone

=sites of attachment for muscles, tendons, and ligaments,

-passage for nerves and blood vessels

Categories of bone markings

-Projections or processes—grow out from the bone surface

-Depressions or cavities—indentations

Osteon (Haversian system)

A unit of bone containing central canal and matrix rings

Central (haversian) Canal

-opening in the center of an osteon

-carries blood vessels and nerves

Perforating (Volkman's) Canal

-canal perpendicular to the central canal

-carries blood vessels and nerves

Lacunae

-Cavities containing bone cells (osteocytes)

-Arranged in concentric rings

Lamellae

-rings around the central canal

-sites of lacunae

What are canaliculi?

Tiny canals

What do canaliculi radiate from?

The central canal to lacunae

What do canaliculi connect?

All bone cells to a nutrient supply

What is the primary material of the skeleton in human embryos?

Hyaline cartilage

What happens to much of the hyaline cartilage during human development?

It is replaced by bone

Where does cartilage remain in the adult human skeleton?

In isolated areas such as the bridge of the nose, parts of ribs, and joints

Epiphysial plates allow…

-lengthwise growth of long bone during childhood

-new cartilage is continuously formed

-cartilage is broken down

-enclosed cartilage is digested away by the osteoclasts, opening up a medullary cavity

-bone replaces cartilage through the action of osteoblasts

What happens to bones until growth stops?

Bones are remodeled and lengthened.

What are the two factors that bones are remodeled in response to?

Blood calcium levels and the pull of gravity and muscles on the skeleton.

Osteocytes

mature bone cells

How do bones grow in width?

Through oppositional growth.

osteoblasts

bone forming cells

osteoclasts

Bone-destroying cells

-breakdown bown for remodeling and release of calcium in response to parathyroid and hormone

process of bone remodeling is performed by both

osteoblasts and osteoclasts