Dr. Ahmed Fathalla Ibrahim

VERTEBRAL COLUMNVERTEBRAL COLUMN

VERTEBRAL COLUMNVERTEBRAL COLUMN

• Mesenchymal cells from Mesenchymal cells from sclerotome sclerotome are found in 3 areas:

1.1.Around notochordAround notochord

2.2.Around neural tubeAround neural tube

3.3.In body wall near to notochord & In body wall near to notochord & neural tubeneural tube

VERTEBRAL COLUMNVERTEBRAL COLUMN

• Mesenchymal cells around notochord: Mesenchymal cells around notochord: form bodies of vertebraeform bodies of vertebrae

• Mesenchymal cells around neural tube: Mesenchymal cells around neural tube: form vertebral (neural) arches form vertebral (neural) arches

• Mesenchymal cells in body wall: Mesenchymal cells in body wall: form form costal processes (give ribs in thoracic costal processes (give ribs in thoracic region)region)

FORMATION OF BODYFORMATION OF BODY At 4At 4thth week week, , each sclerotome is formed

of:

1.1.A cranial part of loosely arranged cellsA cranial part of loosely arranged cells

2.2.A caudal part of densely packed cellsA caudal part of densely packed cells The densely packed cells of one The densely packed cells of one

sclerotome fuse with the loosely sclerotome fuse with the loosely arranged cells of succeeding arranged cells of succeeding sclerotome to form sclerotome to form centrumcentrum (primordium of body)(primordium of body)

FORMATION OF BODYFORMATION OF BODY

As a result:As a result:Each centrum develops from 2 adjacent Each centrum develops from 2 adjacent

sclerotomes (intersegmental)sclerotomes (intersegmental)Nerves lie in close relation to discsNerves lie in close relation to discsArteries (first intersegmental) now lie Arteries (first intersegmental) now lie

on each side of vertebral bodieson each side of vertebral bodiesNotochord degenerates where it is Notochord degenerates where it is

surrounded by vertebral bodiessurrounded by vertebral bodies

INTERVERTEBRAL DISCINTERVERTEBRAL DISC

• Nucleus pulposus: Nucleus pulposus: notochord notochord (between vertebral bodies)(between vertebral bodies)

• Annulus fibrosus: Annulus fibrosus: surrounding surrounding mesenchymemesenchyme

VERTEBRAL DEVELOPMENTVERTEBRAL DEVELOPMENT

VERTEBRAL DEVELOPMENTVERTEBRAL DEVELOPMENTCartilaginous stage Cartilaginous stage

At 6At 6thth week, week, chondrification centers appear

At the end of embryonic period, At the end of embryonic period, the 2 centers in centrum fuse then fuse with those of vertebral arches

VERTEBRAL DEVELOPMENTVERTEBRAL DEVELOPMENTBony stage Bony stage

Primary ossific centersPrimary ossific centers:: Present by the end of embryonic periodthe end of embryonic period Three in number Three in number (one in centrum , one

in each half of vertebral arch) The 2 halves of vertebral arches fuse at

3-5 years 3-5 years (first in lumbar, fusion proceeds cranially)

Vertebral arches articulate with centrum through neurocentral joints neurocentral joints until 3-6 years 3-6 years when fusion occurs

VERTEBRAL DEVELOPMENTVERTEBRAL DEVELOPMENTBony stageBony stage

Secondary ossific centersSecondary ossific centers:: Appear after pubertyafter puberty Five in number Five in number (two in body , one at tip

of spinous process, one at tip of each transverse process)

All centers unite around 25 yearsaround 25 years

DEVELOPMENT OF RIBSDEVELOPMENT OF RIBS

Ribs develop from costal processes in costal processes in thoracic regionthoracic region:

1.They become cartilagecartilage during embryonic periodembryonic period

2.They ossifyossify during fetal periodfetal period

3.Site of union with vertebra is replaced by costovertebral jointcostovertebral joint

Costal processes in other region fuse with transverse processes of vertebrae

DEVELOPMENT OF STERNUMDEVELOPMENT OF STERNUM

Appears in the form of 2 vertical 2 vertical mesenchymal bars (sternal bars)mesenchymal bars (sternal bars)

FusionFusion of 2 bars occurs craniocaudallycraniocaudallyChondrificationChondrification occurs during fusionduring fusionOssification centers Ossification centers appear

craniocaudally craniocaudally before birth before birth EXCEPT for xiphoid process (during childhoodduring childhood)

DEVELOPMENT OF CRANIUMDEVELOPMENT OF CRANIUMTHE CRANIUM CONSISTS OF:THE CRANIUM CONSISTS OF:

• NEUROCRANIUM:NEUROCRANIUM: PROTECTIVE CASE PROTECTIVE CASE FOR BRAINFOR BRAIN

• VISCEROCRANIUM:VISCEROCRANIUM: SKELETON OF SKELETON OF FACEFACE

• EACH PART IS SUBDIVIDED INTO:EACH PART IS SUBDIVIDED INTO:

• CARTILAGINOUS PART: CARTILAGINOUS PART: OSSIFY BY ENDOCHONDRAL OSSIFICATIONENDOCHONDRAL OSSIFICATION

• MEMBRANOUS PART:MEMBRANOUS PART: OSSIFY BY INTRAMEMBRANOUS OSSIFICATIONINTRAMEMBRANOUS OSSIFICATION

DEVELOPMENT OF CRANIUMDEVELOPMENT OF CRANIUM

CARTILAGINOUS CARTILAGINOUS NEUROCRANIUMNEUROCRANIUM

PARACHORDAL CARTILAGE:PARACHORDAL CARTILAGE: Forms around cranial end of notochord around cranial end of notochord Forms occipital bone (together with occipital bone (together with

sclerotome of occipital somites)sclerotome of occipital somites)

HYPOPHYSEAL CARTILAGES:HYPOPHYSEAL CARTILAGES: Form around pituitary glandaround pituitary gland Fuse to form body of sphenoid bonebody of sphenoid bone

CARTILAGINOUS CARTILAGINOUS NEUROCRANIUMNEUROCRANIUM

ALA ORBITALIS:ALA ORBITALIS: Forms lesser wing of sphenoid bone lesser wing of sphenoid boneOTIC CAPSULES:OTIC CAPSULES: Form petrous & mastoid parts of petrous & mastoid parts of

temporal bonestemporal bonesTRABECULAE CRANII & NASAL TRABECULAE CRANII & NASAL

CAPSULES:CAPSULES: Fuse to form ethmoid bone ethmoid bone

MEMBRANOUS MEMBRANOUS NEUROCRANIUMNEUROCRANIUM

• Forms the calvaria (cranial vault): the calvaria (cranial vault): frontal & parietal bonesfrontal & parietal bones

• Bones are separated by fibrous joints fibrous joints (sutures)(sutures)

• Six fontanelles Six fontanelles (site of meeting of several sutures) are present

CARTILAGINOUS CARTILAGINOUS VISCEROCRANIUMVISCEROCRANIUM

Derived from pharyngeal arches:Derived from pharyngeal arches: Dorsal end of 1Dorsal end of 1stst arch: arch: malleus & incusmalleus & incus Dorsal end of 2Dorsal end of 2ndnd arch: arch: stapes & styloid stapes & styloid

process of temporal boneprocess of temporal bone Ventral end of 2nd arch: Ventral end of 2nd arch: lesser horn & lesser horn &

superior part of body of hyoid bonesuperior part of body of hyoid bone Ventral end of 3Ventral end of 3rdrd arch: arch: greater horn & greater horn &

inferior part of body of hyoid boneinferior part of body of hyoid bone

MEMBRANOUS MEMBRANOUS VISCEROCRANIUMVISCEROCRANIUM

• Squamous part of temporal boneSquamous part of temporal bone

• Maxillary boneMaxillary bone

• Zygomatic boneZygomatic bone

• MandibleMandible

POSTNATAL GROWTH OF POSTNATAL GROWTH OF CRANIUMCRANIUM

At birth, At birth, calvaria is larger than facecalvaria is larger than face Increase in size of calvaria is greatest

during first 2 years during first 2 years (period of most rapid postnatal growth of brain)

Rapid growth of face & jaws coincide with:

1.Eruption of teeth

2.Development & enlargement of paranasal sinuses (which are absent or rudimentary at birth)

SPINA BIFIDASPINA BIFIDA

Cause:Cause: Failure of fusion of the halves of the vertebral arch

Incidence:Incidence: 0.04 – 0.15% Sex:Sex: more frequent in femalesin females Types:Types:

1.1.Spina bifida occulta (20%)Spina bifida occulta (20%)

2.2.Spina bifida cystica (80%)Spina bifida cystica (80%)

SPINA BIFIDASPINA BIFIDA

SPINA BIFIDA OCCULTASPINA BIFIDA OCCULTAThe closed typeThe closed typeOnly one vertebra is Only one vertebra is affectedaffectedNo clinical symptomsNo clinical symptomsSkin over it is intactSkin over it is intactSometimes covered by Sometimes covered by a tuft of haira tuft of hair

SPINA BIFIDA CYSTICASPINA BIFIDA CYSTICA

with meningomyelocelewith meningomyelocele with with myeloschisismyeloschisis

SPINA BIFIDA CYSTICASPINA BIFIDA CYSTICA• The open typeThe open type• Neurological symptoms are presentNeurological symptoms are present• Subdivided into:Subdivided into:

1.1. Spina bifida with meningocele: Spina bifida with meningocele: protrusion of sac containing meninges & cerebrospinal meninges & cerebrospinal fluidfluid

2.2. Spina bifida with meningomyelocele: Spina bifida with meningomyelocele: protrusion of sac containing meninges with meninges with spinal cord and/or nerve rootsspinal cord and/or nerve roots

3.3. Spina bifida with myeloschisis: Spina bifida with myeloschisis: spinal cord is spinal cord is open (due to failure of fusion of neural folds)open (due to failure of fusion of neural folds)

CRANIOSYNOSTOSISCRANIOSYNOSTOSIS

CRANIOSYNOSTOSISCRANIOSYNOSTOSIS• Premature closure of cranial sutures Premature closure of cranial sutures

(more severe if occurs prenatally)(more severe if occurs prenatally)

• Sex: Sex: more frequent in malesmore frequent in males

• Types:Types: depend upon which suture depend upon which suture closes prematurelycloses prematurely

1.1.ScaphocephalyScaphocephaly (50%): (50%): sagittal suturesagittal suture

2.2.OxycephalyOxycephaly (30%): (30%): coronal suturecoronal suture

3.3.PlagiocephalyPlagiocephaly: : both coronal and both coronal and lambdoid sutures on one sidelambdoid sutures on one side

4.4.TrigonocephalyTrigonocephaly: : frontal suturefrontal suture