Skeletal System Flashcards
mesenchyme forms _________ _________, which appear in week 5
chondrification centers
produce cartilage material
chondroblasts
forms bases for most of the skeleton
chondrification centers
maintenance cells for hyaline cartilage
chondrocytes
four jobs of bone
structural framework
protection of organs
attachment for muscle
storage for minerals
shaft of long bone
diaphysis
articular ends of long bone
epiphysis
growth plate - cartilage, separates growing bones
epiphyseal plate
between diaphysis and epiphysis
metaphysis
anchored by Sharpey’s fibers and covers diaphysis
periosteum
four kinds of bone
woven bone
lamellar bone
cortical (compact) bone
trabecular bone
composed of lamellar bone arranged in osteons
has periosteal and endosteal surfaces
cortical (compact) bone
type of bone present in medullary cavity and ends of long bones
trabecular (spongy) bone
forms at sites of periosteal injury and is temporary
woven bone
type of bone that contains lacunar osteocytes
lamellar bone
provides tensile strength and flexibility in collagenous organic matrix
type I collagen
_________ stimulates the glycoproteins in non-collagenous organic matrix
vitamin D
non-mineralized bone matrix
osteoid
gives bones hardness; storage site for calcium and phosphorus
hydroxyapatite
bone forming cells
produce organic matrix by surrounding itself (osteoid)
have PTH receptors
osteoblasts
mature bone cells
located in lacunae
radiate in all directions in canaliculi
osteocytes
help regulate minute-to-minute Ca influx (2)
osteoblasts and osteocytes
osteoclasts are derived from_________
monocytes
places for resorption of bone; where osteoclasts sit
Howship’s lacuna
bone removing cells (resorb bone); respond indirectly to PTH
osteoclasts
why do concentric lamellae run perpendicular to each other?
creates strength
another name for osteon
Haversian canal
outermost boundary of osteon
cementing line
bone forms within an accumulation of mesenchymal or fibrous tissue; no cartilage model
intramembranous ossification
bone forms in a cartilage model; cartilage is removed and replaced by bone
endochondral ossification
has 5 zones and provides longitudinal bone growth
epiphyseal plate
5 zones of epiphyseal plate
resting zone/reserve cartilage
proliferation
hypertrophy and maturation
calcification
ossification
Describe intramembranous ossification
mesenchyme condense and differentiate cells to form osteoblasts.
osteoblasts deposit osteoid and get trapped to form osteocytes
this process forms lamellae, which then from osteons
Describe the primary center of endochondral ossification
appears in diaphysis and develops towards epiphysis
matrix becomes calcified and perichondrium becomes periosteum
**diaphysis is ossified by birth
describe secondary centers of endochondral ossifiaction
appear in epiphysis during first few years of life
when does epiphyseal plate become ossified?
when growth is complete
~20 years
on which side is cartilage replaced in length-wise bone growth?
diaphyseal side
describe width-wise bone growth (and another name for it)
bone deposits at the periosteum and resorption at the endosteum
aka appositional growth
bone production + resorption to allow adaptation of skeleton
occurs throughout life
remodeling
what is Wolff’s Law?
bone will remodel to accommodate the stress placed on it
Factors stimulating bone production (3)
Growth hormone
calcitonin (from parathyroid cells)
Bone compression
Factors stimulating bone resorption (2)
PTH
Bone tension
when do vertebrae begin developing
week 4
what are sclerotomes
paired tissue from somites that begin to surround notochord (week 4 - vertebral development)
cranial sclerotomes are _________ arranged
caudal sclerotomes are _________ arranged
loosely
densely
what is the centrum
beginning vertebral body
what do sclerotomes form? (2)
IV discs
centrum
when do chondrification centers appear in mesenchyme in vertebral development?
week 6
extension of chondrification centers develop (2)
spinous processes
transverse processes
Vertebral development
Week 12:
At birth:
At puberty:
week 12: primary ossification centers are present
at birth: fusion of vertebral arch and centrum (caudal to cranial)
At puberty: secondary ossification centers present in spinous, transverse, and body (2)
what is hemivertebra
failure of 2 chondrification centers to unite
leads to scoliosis
what is the calvaria
skull cap
what are fontanelles
6 fibrous areas that allow calvaria to undergo changes in shape during birth
bone around brain
neurocranium
3 bones at base of cranium that undergo endochondral ossification
occipital bone
sphenoid
ethmoid
bones forming face
viscerocranium
viscerocranium forms from ______
1st pharyngeal arch
premature closure of cranial sutures
- scaphocephaly (sagittal)
- brachycephaly (coronal)
craniosynostosis
appendicular development begins in week ___ and is regulated by ______ and patterning pathways
6
Hox genes
which appears first?
pectoral girdle and upper limbs
pelvic girdle and lower limbs
pectoral girdle and upper limbs
primary ossification centers of limb bones appear in week ___
12
first bone to ossify
clavicle
rate of ossification of this bone is used to predict gestational age
femur
when do secondary ossification centers first appear
34 - 38 weeks
affects endochondrial ossification and disrupts growth at epiphyseal plates in fetal growth
achondroplasia
six steps of fracture healing
hematoma (1 hour)
hematoma and bone necrosis (1-2 days)
organization of hematoma - soft callus (1-2 weeks)
early ossification (3-8 weeks)
late ossification with remodeling - hard callus (2-8 months)
healed and remodeled fracture (1-3 years)
joint with greatest range of motion
has cavity filled with fluid, surrounded by joint capsule
bone surfaces lined by articular cartilage
synovial joint
joint with minimal range of motion
lacks a joint cavity
fibrous joint
three types of fibrous joint
synostosis: interdigitating bone
synchondrosis: hyaline cartilage
syndesmosis: fibrous tissue/fibrous cartilage
leads to epiphyseal plate chondrodystrophy (Rickets)
vitamin D deficiency
deficiency of vitamin C affecting collagen production of bone matrix
scurvy
accumulation of unmineralized osteoid
osteomalacia
