Anaphy lec 26-50page

Anatomy of a long bone

•Marrow (medullary) cavity

•Cavity inside of the shaft

•Contains yellow marrow (mostly fat) in adults

•Contains red marrow for blood cell formation in infants

•Projections or processes—grow out from the bone surface

Terms often begin with “T”

•Depressions or cavities—indentations

•Terms often begin with “F”

Microscopic Anatomy of Compact Bone

•Osteon (Haversian system)

A unit of bone containing central canal and matrix rings

Microscopic Anatomy of Compact Bone

•Central (Haversian) canal

•Opening in the center of an osteon

•Carries blood vessels and nerves

Microscopic Anatomy of Compact Bone

•Perforating (Volkmann’s) canal

•Canal perpendicular to the central canal •Carries blood vessels and nerves

Microscopic Anatomy of Bone

•Lacunae

•Cavities containing bone cells (osteocytes) •Arranged in concentric rings called lamellae

Microscopic Anatomy of Bone

•Lamellae

•Rings around the central canal

•Sites of lacunae

Microscopic Anatomy of Bone

•Canaliculi

•Tiny canals

•Radiate from the central canal to lacunae

•Form a transport system connecting all bone cells to a nutrient supply

Formation of the Human Skeleton

In embryos, the skeleton is

primarily hyaline cartilage

Formation of the Human Skeleton

During development, much of this cartilage is

replaced by bone

Formation of the Human Skeleton

•Cartilage remains in isolated areas

•Bridge of the nose

•Parts of ribs

•Joints

Bone Growth (Ossification)

•Epiphyseal plates allow for

lengthwise growth of long bones during childhood

•New cartilage is continuously formed

•Older cartilage becomes ossified

•Cartilage is broken down

Bone Growth (Ossification)

Enclosed cartilage is digested away, opening up

a medullary cavity

•Bone replaces cartilage through the action of

osteoblasts

Bone Growth (Ossification)

•Bones are remodeled and lengthened until growth stops

•Bones are remodeled in response to two factors

•Blood calcium levels

•Pull of gravity and muscles on the skeleton

Bone Growth (Ossification)

•Bones are remodeled and lengthened until growth stops

•Bones are remodeled in response to two factors

•Blood calcium levels

•Pull of gravity and muscles on the skeleton

•Bones grow in width (

(called appositional growth)

Types of Bone Cells

•Osteocytes-

mature bone cells

Types of Bone Cells

Osteoblasts-

bone-forming cells

Types of Bone Cells

Osteoclasts-

giant bone-destroying cells

•Break down bone matrix for remodeling and release of calcium in response to parathyroid hormone

•Bone remodeling is performed by both osteoblasts and osteoclasts

Bone Fractures

•Fracture-

break in a bone

•Bone fractures are treated by reduction and immobilization

Types of bone fractures

•Closed (simple) fracture-

break that does not penetrate the skin

•Types of bone fractures

•Open (compound) fracture-

broken bone penetrates through the skin

•Comminuted-

bone breaks into many fragments

•Compression-

bone is crushed

•Depressed—

broken bone portion is pressed inward

Impacted-

broken bone ends are forced into each other

•Spiral—

ragged break occurs when excessive twisting forces are applied to a bone

•Greenstick—

bone breaks incompletely

Repair of Bone Fractures

•Hematoma (blood-filled swelling) is formed

•Break is splinted by fibrocartilage to form a callus

•Fibrocartilage callus is replaced by a bony callus

•Bony callus is remodeled to form a permanent patch