Skeletal system

The adult human skeleton usually consist of 206 named bones

These bones can be grouped into two divisions axial, which includes the skull spine and rib cage and appendicular, which includes arms, legs, hands, and feet

The 80 bones in the axial skeleton formed the central axis of the body

Functions of the skeletal system

Support (framework)

Protection (vital organ organs)

Movement (Muscle attachment)

Blood cell formation (in red bone marrow)

Storage (fat and yellow marrow and calcium and matrix)

classification

Bones are classified According to shape

Long (longer than wide, has shaft +2 ends. Examples are humorous and phalanges).

Short (cube like bones, wrists and ankles)

Flat(Thin, flattened, usually curved; sternum, ribs, Most bones in skull)

Irregular (Bones not in other classes; vertebrae, sacrum, coccyx, some skull bones)

Sesamoid (small, flat bones; shape like sesame seed; develop within an attendance; function to decrease stress on tendon; patella (kneecap) and bones in foot)

Surface markings

All bones have surface markings that make them unique

These usually represent passageways for vessels and nerves, points of articulation with other bones, or points of attachment for tendons and ligaments

Structures of a long bone

epiphyses (expanded ends of bones)

Diaphysis ( is the long axis or shaft (middle) of a long bone)

Outer ends of epiphyses are coated with cartilage (hyaline) that cushions the ends of bones

The tough outer covering is called periosteum (anchor points for tendons and ligaments.)

Wall of diaphysis is composed of tightly packed tissues called compact bone

epiphyses are composed of sponge bone ( lots of open spaces with bony plates called trabeculae)

inside the diaphysis of long bones is a hollow chamber called the medullary cavity ( It contains fat and yellow marrow)

The medullary cavity is lined with a thin layer of cells called endosteum

Microscopic, compact bone tissue

Compact bone is composed of osteons cemented together by bone matrix

Osteon consist of concentric layers of compact bone tissue that surround a central canal blood vessels

Concentric layers are layers of circles

Bone cells are arranged in rings called lamellae around a canal system of arteries and veins called Haversian canals.

Haversian canals run longitudinally (up and down) within compact bone

Volkman’s canals run perpendicular (Left to right) and connect periosteum to Haversian canals, and the medullary cavity

One ring is made up of osteocytes (mature bone cells) within the little chambers called Lunacunae (caves)

As bones grow, they add more osteocytes and concentric layers, and these rings are called lamellae

these osteocytes are connected to each other by Haversian canals, and by tiny roadways called canaliculi

canaliculi allow nutrients/waste exchange between cells and blood

Bone development and growth

The formation of bone is called ossification

Osteoblasts are bone, forming cells and form new bone tissue

Mature bone cells are called osteocytes

Osteoclasts are bone reabsorbing cells and breakdown bone matrix (demo team so osteoplast can remodel)

An adult the total mass of bone tissue remains relatively constant

Factors affecting bone development, growth, and repair

Include nutrition, hormonal, secretions, and physical exercise

Bone Fractures

simple fracture (bone breaks, cleanly, does not penetrate skin )

Compound fracture (broken and protrudes through skin; possible Infection)

Comminuted fracture ( Fragments into many pieces; Crush, splinters)

transverse fracture(Break occurs at a right angle to the axis of the bone )

Spiral fracture (caused by excessive, twisting of a bone)

greenstick fracture (bone breaks incomplete like a twig common in children; attached on one side)

Oblique (break occurs at an angle)

Bone repair in four steps

1) hematoma formation (broken vessel and bone causes blood filled swelling)

2) Fibrocartilage formation (forms spongy bone tissue; capillaries regrow)

3) Hard bony callus formation (Replaces the fibrocartilage)

4) Remodeling (bony callus is converted to compact bone; about 12 months)

Osteoporosis

Condition in which bone breakdown outpaces bone formation

Bones, weak, and may break easily

Most often seen in the elderly

Need diet rich In calcium

Cleft lip and palate

Maxillary bones/tissue do not fuse properly during embryonic development (bones don’t fully close)

Not always one identifiable cause

Often detected on fetal ultrasound prior to birth

Often requires multiple surgeries to correct

Cleft lip

Lip forms between fourth and seventh week of pregnancy

About one and every 2800 babies are born with cleft lip without cleft palate in the United States

Cliff lip and palate can occur simultaneously

Cleft palate

Occurs much the same way as cleft lip, but the cleft palate results from incomplete fusion of the Palatine processes of the Maxillae

Complications of both feeding difficulty and speech/language delay