Ossification Centers

Description:	FAB - Ossification Centers
Category:	Chiropractic
Created by:	thenathan on 2008-10-22

Question	Answer
Primary ossification centers begin before or after birth?	Before
Secondary ossification centers begin before or after birth?	after
Ossification is the 1st, 2nd, etc.. stage of vertebral development?	the Last stage
What happens in chondrification?	The embryo has the mesodermal layer being replaced by the cartilage.
When has chondrification completed?	Usually by the 3rd fetal month
When does ossification occur, time wise?	In the 10th week of embryonic development.
When are primary ossification centers usually completed?	By 3 to 6 yrs of age
In cervical vertebrae except C1 & C2, where are the primary ossification centers?	1 in vert body; 1 in each of the vert arches (lamina and pedicles)
Where are the 2ndary ossif. centers in C3-C7?	epiphyseal plates of the vert body, tip of each TP, and tip of each SP
Where are primary ossif. centers in all thoracic vert?	1 in vert body; 1 in each of the vert arches (lamina and pedicles)
Where are 2ndary ossif. centers in all thoracic vert?	epiphyseal plates of the vert body, tip of each TP, and tip of each SP
Time wise, when do 2ndary centers appear and complete?	Appear during 18th yr of life, completed by 25.
Where are the secondary ossifications of the Lumbar?	epiphyseal plates of the vert body, tip of each TP, and tip of each SP
Where are the 1 ossif. centers of ATLAS?	1 in each of lateral masses.
Where are the 2ndary ossif. centers of ATLAS?	On the anterior arch.
Where are the prim. ossif. centers of C2?	1 in the body, 1 in each arch, 2 in base of odontoid process.
Where are the 2ndary ossif. centers of C2?	1 in apex of dens. 1 @ bottom of vert body where ant-inf. lipping starts.
The mesodermal stage is marked by the ____condensation of the ___ ____ around the ____.	mesenchymal; paired sclerotomes; notochord
What happens to each of the sclerotomes during the mesodermal stage?	They become more dense
In mesodermal stage, how do the sclerotomes get separated in half?	a horizontal fissure aka intervertebral fissure occurs to separate the sclerotomes in half
Where does chondrification initially appear?	In the cervical region.
What's the purpose of the primary ossif. centers	To protect the spinal cord
Where do primary ossif. centers begin and progress?	Begin in lower thoracic or upper lumbar and progress to cervical spine.
Which sections of the spine are last to show ossification?	sacral and coccygeal
How many primary ossif. centers do C3-C7 and thoracic have?	5
How many secondary ossif. centers do C3-C7 and thoracic have?	5
How many primary ossif. centers do lumbar vertebrae have?	7
Where are the prim. ossif. centers of lumbar?	1 in vert body, 1 in each arch, 1 in each mamillary process
How many prim. ossif. centers of atlas?	2
How many second. ossif. centers of atlas?	1
How many prim. ossif. centers of axis?	7
How many sec. ossif. centers of axis?	2
Where are the prim. ossif. centers of sacrum?	1 in body of each segment; 1 in each vert arch of each segment; 2 on anterior part of each side of S1, S2, S3 only
Where are the sec. ossif. centers of sacrum?	1 in each epiphyseal plate in each segment; 1 in each auricular surface.
How many prim. ossif. centers in coccyx?	ZERO
How many sec. ossif. centers in coccyx?	1 in center of each segment
What is a hemivertebra?	A failure of 1 lateral half of vert. to develop or ossify with the opposite half.
What is a butterfly vertebra?	A malformation in posterior vertebral segments (mostly laminae)
In a buttefly vertebra, what happens to the ossif. centers?	Lateral ossif. centers fail to grow and unite ENOUGH
What is a block vertebra?	A failure of the formation of IVD resulting in fusion of adjacent vert. fusion during ossification.
What are 2 types of block vertebra?	Congenital & acquired/surgical
What's the appearance of congenital block vert. on x-ray?	Flat, smooth, peripheral surface in region of missing intersegmental disc.
What's the appearance of acquired/surgical block vert. on x-ray?	appears prominent and irregular at disc level.
What is spina bifida?	Failure of fusion of lamina of arch during embryonic period.
What % of population has spina bifida?	10%
What are transitional vertebra?	Vertebra in 1 region of spine takes on appearance of vert they are approaching
What % of ppl have sacralization?	5%
What is sacralization?	When L5 vert is partially or completed fused into sacrum
What is lumbarization?	When S1 does not fuse w/ sacrum. Feels like a 6th lumbar vertebra.
What is spondylosis?	General degeneration of spinal column.
What is spondylolysis?	A defect in interarticular part of vert.
Which segment of spine is spondylolysis usually seen ?	Lumbar
What is spondylolosthesis?	Slippage of vert. body on vert below.
Which segment of spine is spondylolosthesis usually seen?	Lumbar