skeletal system

function of bone
muscle attachment,protection and support, blood cell production and support and storage of materials
parts of the long bone that are expanded ends of bones that form joints with adjacent bones
articular cartilage
covers the epipiphyses and made of hyaline cartilage
shaft of the bone
tough layer of vascular connective tissue that covers the bone and is continuous with ligaments and tendons, functions in the formation and reparation of bone tissue, forms by cells of the membranous connective tissue that lie outside the developing bone
a bone's shape
makes possible its function
bony processes or projections
sites of attachment for ligaments and tendons
compact bone
makes up the wall of diaphysis and is made of osteocytes, osteons, that contain blood vessels and nerve fibers lots of matrix arranged around osteonic canals etc..
spongy bone
fills the epiphysis and reduces the weights of the skeleton ( more at ends of bones), more space, no osteocytes, less matrix, not arranged around osteonic canals
medullary cavity
hollow cavity in diaphysis lines with endosteum and filled with marrow (tissue)
bones are classified
by bone shape
long bones
longitudinally long, expanded ends. example = forearm, thigh
short bones
cube-like, equal width and length. example= bones of wrists and ankles
flat bones
plate-like with broad surfaces. example= ribs, scapulae, some cranial
irregular bones
various shapes, but usually connected to other bones. example= facial bones, vertebrae
sesamoid bones
round,small and nodular. example= kneecap
bone cells
spaces where osteocytes are
osteonic ( central ) canals
osteocytes within lacunae lie in concentric circles around these
osteocytes pass nutrients and gases in the this through canaliculi, consists of collagen and inorganic salts
extends of cell membrane or osteocytes cell processes
perforating canal
osteonic canals that are interconnected by transverse _________
osteonic canals
contain blood vessels and nerve fibers and extend longitudinally through the bone
intramembranous bones
form by the formation of bone within sheetlike layers of connective tissue (unspecialized)
endochondral bones
form by replacing connective tissues ( hyaline cartilage) in the fetus
example of intramembranous bones
deposit bony tissue around themselves
once osteoblasts deposit bone and are located in the lacunae, they are called this
formation of bone
primary ossification center
formation of spongy bone where cartilage is replaced by spongy bone in the diaphysis cartilage is broken down in the diaphysis and progessively develops on the outside, cartilage tissue is invaded by blood vessels and osteoblasts that first form spongy bone at the primary ossification center (most bones) and osteoblasts beneath the periosteum lay down compact bone on the outside of spongy bone
secondary ossification center
appears later in ossification in the epiphysis, the epiphyseal plate forms between the two ossification centers, osteoclasts break down the calcified matrix and are replaced with bone-building osteoblasts that deposit bone in place of calcified cartilage. a medullary cavity forms in the region of the diaphysis due to the activity of the osteoclasts
epiphyseal plate
a band of hyaline cartilage between the two ossification centes and is a layer of cartilage cells undergoing mitosis. it is responsible for lengthening bones
increase in bone thickness due to
intramembranous ossification underneath the periosteum
tear down
build bone throughout the lifespan with the processes of resorption and deposition with an average of 3-5% of bone calcium exchanged annually by the good blood supply ( mass remains relatively constant)
bone function
support and protection, give shape to head, thorax, and limbs. pelvis bones give support, skull protects the brain, ears, and eyes
has four components, a rigid bar, a pivot or fulcrum ( point of connection), an object that is moves against resistance, and a force( from muscle) that supplies energy
blood cell formation
begins to form through hematopoieses in the yolk sac and later in the bone marrow
red marrow
functions in the formation of red blood cells, white blood cells, and platelets, and is found inthe spongy bone of the skull, ribs, sternum, clavicles, vertebrae, and pelvis
yellow marrow
occupying the cavities of most bones, stores fat
storage of inorganic salts
the inorganic matrix of bone stores inorganic mineral salts in the form of calcium phosphate that is important in many metabolic processes
calcium in the bone functions as
a reservoir for body calcium, when blood levels are low, osteoclasts release calcium from the bone ( important in nerve impulses, muscle contractions, and blood clotting)
hormone secreted by the thyroid when calcium levels in the blood are too high and causes calcium to be stored in the bone
bone stores ___ outside of calcium
magnesium, sodium, potassium, and carbonate ions ( used in metabolic processes, maintianing homeostasis, and active transport in cells)
harmful elements that bone can accumulate
lead, radium, and strontium
if calcium levels in the blood are too high
cells in the thyroid gland sense the increase in the blood calcium concentration and the thyroid gland releases calcitonin, osteoblasts then deposit calcium in the bones to return to normal ( as calcium phosphate)
if calcium levels in the blood are too low
cells in the parathyroid gland sense the decrease in blood calcium, then release a parathyroid hormone causing osteoclasts to break down bone to release calcium
changes in blood calcium concentration occur by
dietary, hormonal, or genetic issues
an issue of the thyroid may be diagnosed by
off calcium concentrations
axial skeleton
consists of the skull , vertebral column and thorax
appendicular skeleton
consists of the pectoral girdle, upper limbs, pelvic girdle, lower limbs
made up of 22 bones, 8 cranial an 13 facial and the mandible
encloses and protects the brain, provides attachments for muscles, and contains air-filled sinuses that reduce its weight
frontal bone
includes the supraorbital foramen and frontal sinuses
union between bones
passageway for blood vessels and nerves in the skull
parietal bones
lie at the sides of the skull and join at the sagittal suture
occipital bone
include the lambdoidal suture, foramen magnum, and occipital condyles
temporal bone
includes the squamosal suture, external acoustic meatus, mandibular process, styloid process (opening in ear) and zygomatic process
sphenoid bone
includes the sphenoidal sinuses
ethmoid bone
includes the ethmoidal sinuses
facial skeleton
includes 13 immovable bones and the mandible to form the basic face and provide attachments for muscles of mastication and expression
forms the upper jaw, hard palate, floor of the orbits, sides of the nasal cavity, house the upper teeth, and contain large maxillary sinuses
palatine bones
L-shaped and found behind the maxillae that form the floor of the nasal cavity and hard palate
zygomatic bones
make up the cheekbones and join with the temporal bones to form the zygomatic arches
lacrimal bones
form part of the medial walls of the orbits
nasal bones
form the bridge of the nose
vomer bone
makes up the portion of the nasal septum
inferior nasal conchae
fragile, scroll-shaped bones that support mucous membranes within the nasal cavity
lower jawbone, supports the lower teeth and includes the mandibular condyle, coronoid process, and alveolar arch
cervical vertebrae
the seven bones are the smallest of the vertebrae that comprise the neck and the support of the head, have a bifid spinous process and transverse foramina
first vertebra and looks like a bony ring to support the head, side side and up down movement
second vertebra with tooth-like dents that pivot within the atlas
thoracic vertebrae
twelve vertebrae that articulate with the ribs, larger and stronger that cervical
lumbar vertebrae
five massive vertebrae that support the weight of the body ( main)
triangular strucutre at the base of the vertebral column made up of five vertebrae fused into one bone ( spinous processes are fused to form a ridge of tubercules that have a dorsal sacral foramina along their sides, 4 on each side)
lowermost portion of the vertebral column and is composed of four fused vertebrae
thoracic cage
includes the ribs, thoracic vertebrae, sternum, and costal cartilages, support the pectoral girdle and upper limbs, functions in breathing and protects the thoracic and upper abdominal organs
normally there are 12 pairs of ribs that attach to thoracic vertebrae, the first seven pairs are vertebrosternal and the remaining five pairs are false ribs, the first three of theses are vertebrocondral, the last two of these are floating ribs
typical rib
includes a shaft, costal groove, anterior end ( sternal), head, neck, and tubercle ( head articulates with the vertebrae, tubercle with the transverse process of the vert)
located along the anterior midline of the thoracic cage, includes upper manubrium, middle body, and lower xiphoid process
pectoral girdle
makes and incomplete ring that supports the upper limbs, includes a two scapulae and two clavicles
elongated s-shaped bones located at the base of the neck that function to brace the scapulae
flat, triangular bones on either side of the upper back, spine divides it into unequal portions
upper limb
bones of the upper limb form the framework for the arm, forearm, and hand
makes up the upper arm, extending from the scapula to the elbow and articulates with the scapulae at its head with the radius at the capitulum and the ulna at the trochlea
located on the thumb side of the forearm, extending from the elbow to the wrist, pivots with the humerus
longer of the two bones making up the forearm and had a trochlear notch that articulates with the humerus
made up of 8 carpal bones bound into a carpus
made up of 5 metacarpal bones
made up of groups of three phalanges in each finger, except the thumb which lacks a middle phalanx
narrow slit-like opening between adjacent parts of bones through which blood vessels and nerves may pass
tube-like passageway
air-filled cavity within a bone that connects to the nasal cavity
prominent projection of a bone that may be articulating or non
articulating, large, knuckle-like projection
in contact or coordination between bones
rounded articulates
small, knob-like and non
smaller projection above condyle non
smooth , flat surface, arti
blunt projection non
hip bone
made up of three bones, the ilium, ischium, and pubis that are fused in the region of the acetabulum
cup-like depression that articulates with the head of the femur
largest and most superior portion of the hip bone and joins the sacrum at the sacroiliac joint
forms the L-shaped portion that supports weight during sitting
comprises the anterior portion of the coxal bones and articulates at the symphysis pubis
obturator foramen
lies within each pubis
greater pelvis
above the pelvic brim ( lesser pelvis is below it)
lower limb
bones here provide the framework for the thigh, lower leg, and the foot
thighbone that extends from hip to the knee and is the longest bone in the body
kneecap that is located in the tendon that passes over the knee
shinbone that supports the weight of the body and articulates with the femur and with the tarsal bones
slender bone lying lateral to the tibia and it does not bear body weight
composed of seven tarsal bones to form the tarsus
articulates with the tibia and fibula and is found in the ankle
calcaneus heel
found in ankle and supports the body weight
instep of foot
consists of five metatarsal bones and provides an arch
made up of phalanges
joints classified by
degree of movement possible, slightly movable, or freely movable or by the type of tissue that binds them together
fibrous joints
are held together by dense connective tissue and are immovable or only slightly movable
example of fibrous joint
suture of skull, between tibia and fibula
cartilaginous joints
made up of hyaline cartilage or disks of fibrocartilage
example of cartilaginous joint
symphysis pubis and first rib of sternum or intervertebral disks
synovial joints
most complex joint made up of hyaline cartilage, joint capsule of an outer layer of dense connective tissue that joins the periosteum and inner synovial membrane which includes synovial fluid, some contain menisci ( shock absorbing pads), or bursae ( fluid-filled sacs)