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Skeletal (Anatomy (Bone Healing Stages (Fibrocartilaginous callus forms…
Skeletal
Anatomy
Bone Healing Stages
Fibrocartilaginous callus forms
New Blood Vessels grow
Fibro and Chondroblasts invade fracture site
fibroblasts produce collagen fibers
chondroblasts secrete cartilaginous matrix
Soft callus splints the broken bone
Bony Callus Forms
Osteoblasts begin to form spongy bone
osteoblasts lay trabeculae around Fibrocartilaginous callus
unite two broken bones
Fibrocartilaginous callus replaced by bony callus
A Hematoma Forms
blood vessels and periosteum are torn
hemorrhaged blood clots
Tissue becomes swollen painful and inflamed
Bone Remodeling Occurs
Bony callus is remodeled
Materials for Bone Growth and Repair
Diet Needed
Rich in calcium, vitamin D, and protein
Bone Process'
formation/ Endochondral Ossification
The periosteal bud invades the internal cavities and spongy bone forms
Periosteal bud has a nutrient artery/vein, nerve fibers, red marrow elements, osteoprogenitor cells, and osteoclasts
^ like a bone starter kit
Osteoclasts erode calcified matrix, op cells become osteoclasts that secrete osteoid
bone-covered cartilage trabeculae,
early spongy bone
The diaphysis elongates and the medullary cavity forms
Primary ossification center enlarges and osteoclasts clear spongy bone to create the medullary cavity
ossification chases the hyaline cartilage in the epiphyses
hyaline cartilage continues to grow and elongate in the epihyses
After Birth: secondary ossification centers develop in one or both epiphyses
large long bones have 2
short and short long bones have one
irregular bones have 1 or more distinct centers
cartliage calcifies in the center of the diaphysis and develops (cavities)
calcification of cartilage kills the hyper chondrocytes
matrix deteriorates and forms cavities
other cartilage areas grow quickly and elongate the bone
The epiphyses ossify
secondary ossification occurs
same as primary but medulla doesnt form and spongy interior is kept
no cavity in epiphyses
spongy bone throughout
bone collar forms around diaphysis
perichondrum > periosteum
mesenchyme cells specialize into osteoblasts
osteoblasts secrete osteoid, collar
chondrocytes in the shaft enlarge and from the primary ossification center
begins in late 2nd month of development
hyaline cartilage model "bones"
full grown bones only have hyaline in the surfaces (articular cartilage on joint surface) and in the epiphyseal plates
more complicated than intramembranous ossification
Intramembranous ossification forms cranial bones of skull and clavicles
Osteoid is secreted and calcifies
trapped osteoblasts become osteocytes
Ossification centers develop in the fibrous connective tissue membrane
mesenchyme cells cluster and form osteoblasts, creating an ossification center
Immature spongy bone and periosteum form
osteoid is laid down around blood vessels which forms spongy bone
condensed/ vascularized mesenchyme on the external side of the bone makes the periosteum
Compact bone replaces immature spongy bone deep to the periosteum, red marrow develops
trabeculae are replaced by compact bone
immature spongy bone in center becomes mature and filled with red marrow
most bones formed from this are flat
remodel
Bone Resorption
Osteoclasts break down the bone matrix
using H+ for inorganic material
using lysosomal enzymes for organic material
Broken down substances are released into intersitial fluid to the blood
Finished osteoclasts undergo apoptosis
dig depressions or grooves into the bone
Bone Deposition
Osteoblasts deposit new bone matrix
called the osteoid seam
organic bone matrix no minerals
a transition between osteoid seam, older mineralized bone called the calcification front
Osteoid becomes calcified through a process
Triggers Osteoblasts to release matrix vesicles studded with alkaline phosphatase
Alkaline Phosphatase cute phosphate ions off of osteoid proteins
Osteoid proteins bind Calcium ions
raises the concentration of P
Calcium Phosphate crystals form
Crystals are like seeds for hydroxipatites
Calcified Bone is Formed
Control of Remodeling
Maintaining Ca2+ homeostasis
Parathyroid Hormone
Keeping Bone Strong
mechanical and gravitational forces act on bone to drive remodeling
Mechanical Stress
Wolff's Law- a bone grows/remodels in response to the demands placed on it
Bone Anatomy reflects common stress encountered
where muscle attachments are bony projections can occur
fetus and elderly have atrophied bones because lack of stress to remodel
Hormonal Control
Blood Calcium levels are critically important for the body
99% of calcium is in the bone and is stored there
Calcium is absorbed in the intestine through calcitriol
Parathyroid Hormone produced by parathyroid gland
when Ca2+ levels drop PTH is released and stimulates osteoclasts to resorb bone which releases Ca2+ into th eblood
when Blood calcium levels rise the stimulus for PTH ends, reversing the effects
Calcitonin helps lower blood calcium levels at pharma doses
Bone Growth
similar to endochondral ossification
Hypertrophic Zone
Older stack chondrocytes enlarge and erode their lacunae
leaves large interconnected spaces
Calcification Zone
cartilage matrix calcifies and the chondrocytes die
matrix deteriorates allowing for blood vessels to invade
calcified cartilage spicules hang
Proliferation Zone
top of epipyhsis near resting zone, growth zone
cells divide quickly, push epiphysis away from diaphysis
entire bone is lengthened
Ossification Zone
medullary cavity releases marrow elements to the calcified spicules
osteoclasts erode cartilage spicules while osteoblasts replace it with bone
spongy bone replaces the spicules
osteoclasts digest spicule tips and the medullary cavity lengthens
needs epiphyseal cartilage
side of epiphyseal plate facing the epiphysis is the resting zone, inactive cartilage
below this, cartilage cells form tall stacked columns
Bone Fracture Classification
Bone Alignment
displaced
bone ends are out of normal alignment
nondisplaced
bone ends retain normal position
Skin Penetration
open
skin is penetrated
closed
skin is not penetrated
Bone is broken through or not
Complete
Incomplete
Anatomy of Long Bones
Long bones are longer than they are wide
has a shaft and two bulkier ends, membranes
Epiphyses
bone ends
hyaline cartilage (articular) covers the joint surface
reduces stress of bone to bone movement
outer shell of compact bone
inner spongy bone
Epiphyseal Line
Located between the epiphyses and diaphysis
area can be called the metaphysis
remnant of the epiphyseal plate
growth plate
disc of hyaline cartilage that grows during childhood to lengthen bone
Membranes
Periosteum
white double layered membrane
Outer Fibrous layer
consists of dense irregular connective tissue
inner osteogenic layer
osteoprogenitor cells
2 more items...
osteoblasts
1 more item...
osteoclasts
1 more item...
Has nerve fibers and blood vessels
why breaking bones hurts and bleeds profusely
perforating fibers
2 more items...
provides anchor points for tendons and ligaments
1 more item...
well vascularized
1 more item...
around the bone, external membrane except joint surfaces which have hyaline/articular cartilage
Endosteum
delicate connective tissue membrane
within the bone
covers internal bone surfaces
covers trabeculae of spongy bone and lines compact bone canals
has osteoblasts, osteoprogenitor, and osteoclasts
Diaphysis
shaft, forms the axis of the bone
compact COLLAR bone external
internal medullary cavity
marrow cavity
no bone tissue
has yellow marrow, fat stored in bone
thin layer spongy bone in between the marrow and compact bone
Spongy Bone is a honeycomb of trabeculae
open spaces in between the trabeculae have red or yellow marrow
all limbs except the patella,wrist and ankle bones are long
typical cartoon "bone"
not based on size but their shape
can be small
phalanges are long bones
12 year-old boy with bone fracture injury
Boy tripped and broke right elbow
brittle bones
poor diet
lactose intolerance
consumes no dairy products
nothing to supplement the calcium from milk
fatty and non nutritious foods
children are forming more bone tissue than reabsorption
because boy lacked calcium, body had to reabsorb more than average child
poor diet and no nutrients exacerbated this
3 or more fragments in a broken bone is a sign of brittle bones
Comminuted Epiphyseal Complete Open Fracture
bone fragments in wound (Comminuted)
common in brittle bones
children normally have more organic matrix in bone
Leads to more flexibility
unusual for a child to have brittle bones
Children do formation more than resorption
lack of calcium in diet means that child had to resorb the bones to supply calcium for brain and blood process
Add calcium, vitamin D, and protein to diet
children commonly have greenstick fractures
important to monitor break so the growth plates are not calcified
bones are bendy like green trees and splinter rather than break
normally in elderly
sign of poor diet
lack of calcium in diet
child only eats junk food and burgers, hot dog, and spaghetti
no calcium because patient is lactose intolerant
infection is possible
Radial Bone Protruding from Upper Arm
Open Fractures have higher chances of infection because wound and bone are exposed
Complete Break makes it easier to set, no need to break it
Open Reduction can be performed and casts, antibiotics given
Olecranon Process "Elbow" is broken
Epiphysis separates from the diaphysis along the epiphysal plate
Epiphyseal Break
dangerous in children
can damage epiphyseal disc
loss of growth if bone fuses incorrectly and the epiphyseal disc calcifies or is cut off from rest of bone
lead to disproportionate limbs
Boy needs diet to change while bone is healing so that he has the correct materials
Monitoring the break and resetting of the bone is very important
if not monitored correctly corrective surgery or physical therapy can be neccesarry to fix the bone