fontanelles (fibrous membranes connecting the cranial bones; fontanelles allow the brain to grow and convert to bone within 24 months after birth
hollow portions of bones surrounding the nasal cavity; functions: lighten the skull and give resonance/amplification to the voice
the only bone that does not articulate (connect with/attach to) another bone; serves as a movable base for the tongue and aids in swallowing and speech
shaft composed of compact bone
ends of the bone composed mostly of spongy bone
outside covering of the diaphysis made up of fibrous connective tissue membrane
secure the periosteum to the underlying bone
supply bone cells with nutrients
covers the external surface of the epiphysis; made of hyaline cartilage; decreases friction at joint surfaces
flat plate of hyaline cartilage seen in young, growing bones
remnant of the epiphyseal plate; seen in adult bones
cavity inside of the shaft; contains yellow marrow (mostly fat) in adults and red marrow (for blood cell formation) in infants and young adults
what are bone markings?
surface features of bones; sites of attachments for muscles, tendons, and ligaments; passages for nerves and blood vessels
2 categories of bone markings
projections/processes and depressions/cavities
grow out from the bone surface
indentations in the bone surface
osteon (Haversian system)
a unit of bone containing central canal and matrix rings
central (Haversian) canal
opening in the center of an osteon that carries blood vessels and nerves
perforating (Volksman's) canal
canal perpendicular to the central canal that carries blood vessels and nerves
cavities containing bone cells (osteocytes) that are arranged in concentric rings
rings around the central canal; sites of lacunae
tiny canals that radiate from the central canal to lacunae; form a transport system that connects all bone cells to a nutrient supply
how many vertebral bones are there?
what are the vertebral bones separated by?
7 vertebrae in the neck
12 vertebrae in the chest region
5 vertebrae associated with the lower back
9 vertebrae fuse to form what 2 composite bones?
the sacrum and the coccyx
curvature of the spine
primary curvatures are the spinal curvatures of the thoracic and sacral regions (present from birth); secondary curvatures are the spinal curvatures of the cervical and lumbar regions (develop after birth)
formed by the fusion of 5 vertebrae
formed by the fusion of 4 vertebrae; "tailbone"
forms a cage to protect major organs; made up of 3 parts (sternum, ribs, and thoractic vertebrae)
in the fetus the skeleton is primarily made of what?
buring development, what replaces cartilage?
where does cartilage remain?
the bridge of the nose, parts of the ribs, and in joints
what is bone growth called?
what allows for lengthwise growth of long bones during childhood?
the epiphyseal plate
what happens during ossification?
new cartilage is continuously formed, older cartilage becomes ossified (turns into bone); cartilage is broken down, enclosed cartilage is digested away, opening up a medullary cavity, bone replaces cartilage through the action of osteoblasts; bones are remodeled and lengthened until growth stops; bones grow in width (appositional growth)
what are the 2 factors that cause bone to be remodeled?
blood calcium levels and the pull of gravity and muscles on the skeleton
bone thinning disease that makes bones fragile and easily fractured; vertebral collapse results in kyphosis (also known as Dowager's hump)
break in a bone
difference between a break and a fracture
types of fractures
closed (simple) open (compound)
closed (simple) fracture
break that does not penetrate the skin
open (compound) fracture
break where the bone penetrates through the skin
how are bone fractures treated?
reduction and immobilization
what is the repair process for bone fractures?
1) hematoma (blood-filled swelling) is formed 2) break is splinted by fibrocartilage to form a callus 3) fibrocartilage callus is replaced by a bony callus 4) bony callus is remodeled to form a permanent patch