A&P 1 chapter 6
Functions of the skeletal system
Hematopoiesis
Production of blood cells; occurs in red bone marrow
Long bones
cylindrical in shape & longer than it is wide
ex. humerus, femur, metacarpals & metatarsals
Short bones
cube like in shape & equal in length, width and thickness
ex. carpals & tarsals
Flat bones
thin bone that is sometimes curved
ex. scapulae, cranial (skull) bones, sternum & ribs
Irregular bones
not an easily characterized shape
ex. vertebrae & many facial bones
Sesamoid bones
shaped like a sesame seed
ex. patella & variable number in tendons
Diaphysis
shaft of long bone
Epiphysis
the proximal & distal ends of the bone
Metaphysis
narrow area between the diaphysis and epiphysis at each end of the bone
Medullary cavity
hollow region in the diaphysis filed with yellow marrow
Epiphyseal plate
area of bone growth in length (growth plate) found in the metaphysis
Epiphyseal line
visible line that remains after the epiphyseal plate stops growing in length after childhood
Endosteum
lining of the medullary cavity; site of bone growth & repair
Periosteum
a fibrous membrane that covers the outer surface of the bone; site of ligament & tendon attachment
Articular cartilage
thin layer of cartilage that reduces friction and acts as a shock absorber at the ends of the bones; made of hyaline cartilage
Diploe
layer of spongy bone between the compact bone outer layers; found in the flat bones like those in the cranium
Articulations
where 2 bones meet; knee joint
Head
prominent rounded surface; head of femur or humerus
Facet
flat surface; vertebrae
Condyle
rounded surface; occipital condyles
Projection
raised markings; spinous process of vertebrae
Protuberance
protruding, chin
Process
prominent feature; transverse process, styloid process
Spine
sharp process; ischial spine, scapular spine
Tubercle
small, rounded process; greater and lesser on humerus
Tuberosity
rough surface; deltoid tuberosity, radial tuberosity
Line
slight elongated ridge
Crest
ridge, iliac crest
Fossa
elongated basin, glenoid fossa
Fovea
small pit; fovea capitis
Sulcus
groove
Canal
passage in bone; auditory canal
Fissure
slit through bone
Foramen
hole through bone; foramen magnum, in occipital bone
Meatus
opening into canal; external auditory meatus
Sinus
air filled space in bone; maxillary sinus (nasal)
Osteocyte
most common type of bone cell; located in the lacunae and maintains bone tissue (a mature bone cell)
Osteoblast
bone cell that forms new bone tissue/matrix (but not new bone cells)
Osteogenic cell
only bone cells capable of mitosis: they divide & form osteoblast which secrete collagen & calcium to form bone tissue & then become osteocytes (stem cell)
Osteoclast
responsible for breaking down bone tissue (reabsorbs bone)
Osteon (Haversian system)
structural unit of compact bone
Central canal
long cylindrical cavity in the center of each osteon containing blood vessels, nerves & lymphatic vessels
Perforating canal (Volkmann's canal)
smaller cylindrical cavities that carry the blood vessels, nerves & lymphatic vessels from the central canal out to the periosteum & endosteum
Canaliculi
canals that connect the osteocytes in the lacunae to each other & also to the central canal
Lacuna
small spaces that each contain an osteocyte; found between the lamellae (or rings)
Lamellae
concentric rings of calcified matrix
Trabeculae
lattice like network of matrix spikes that are arranged to provide maximum strength in spongy bone
Cancellous bone (Spongy bone)
type of bone; it doesn't have osteons but does have osteocytes in lacunae arranged in the trabeculae around open spaces filled with red marrow for hematopoiesis
Compact bone
dense type of bone made of osteons
Hematopoiesis
blood cell production in red bone marrow
Nutrient foramen
small opening in the diaphysis for the passage of blood vessels
2 types of Ossification
1. Intramembranous Ossification
2. Endochondral Ossification
Interstitial growth
growth in the epiphyseal plate which leads to a growth in length for the bone
Appositional growth
growth in the endosteum & periosteum so therefore results in growth in the width/diameter for the bone
Modeling
resorption & laying down new bone during a bone's growth in childhood
Remodeling
resorption & laying down new bone as a result of injury, exercise or any change in strain on the bone
Fracture
any broken bone
Closed reduction
manipulation & the bone in its natural position without surgery
Open reduction
returning a bone to its natural position with use of surgery
Osteoblast
new bone
Osteoclast
old bone
Transverse
occurs straight across the long axis of the bone
Oblique
occurs at an angle that is not 90 degrees
Spiral
bone segments are pulled apart as a result of a twisting motion
Comminuted
Several breaks result in many small pieces between two large segments
Impacted
One fragment is driven into the other, usually as a result of compression
Greenstick
A partial fracture in which only one side of the bone is broken; commonly seen in children
Open (or compound)
a fracture in which at least one end of the broken bone tears through the skin; carries a high risk of infection
Closed (or simple)
a fracture in which the skin remains intact
Fracture Repair
Paget's Disease
disease in patients over 40 years of age with abnormal remodeling of bone due to overactive osteoclasts which leads to weakened & abnormally shaped bones usually in the pelvis & lower extremities but can affect any bones
Osteogenesis imperfecta
genetic disease causing brittle bones subject to frequent multiple fractures
Osteoporosis
decrease in bone mass that occurs with increased age resulting in vertebrae, femur & wrist fractures most commonly
Hypocalcemia
abnormally low calcium levels in blood
Hypercalcemia
abnormally high blood calcium levels
Parathyroid hormone
raises blood calcium levels by activating osteoclasts
Calcitonin
lowers blood calcium by activating osteoblasts