head and neck development: skull & face audrone biknevicius 2005-cpc2
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Head and Neck Development:Skull & Face
Audrone Biknevicius2005-CPC2
CRANIOFACIAL ANOMALIES
•One-third of all congenital defects
•Etiology: •Multifactorial inheritance•Teratogens: alcohol, retinoic acid, toluene, smoking, radiation, hyperthermia •Genetics
4 Week Embryo – Sagittal Section
From Carlson, l999
•Primordial tissues•Stomodeum •Frontonasal prominence
4 Week Embryo - Lateral View
From Carlson, l999
4-8 Week Embryo – Frontal View
From Carlson, 1999
Pharyngeal Arches
•Cranial nerve•Aortic arch (from mesoderm)•Muscle component (from mesoderm)•Cartilaginous rod (from neural crest cells)
Skull
Neurocranium(brain case)
Viscerocranium (face)
•Intramembranous ossification
•Endochondral ossification
Development of Skull
PRIMARY DETERMINANT OF GROWTH & DEVELOPMENT
MembranousCartilagenous
Neurocranium intracranial pressure genetics
Viscerocranium adjacent soft tissues genetics
(tongue, eye)
Neurocranium
•Primarily derived from neural crest cells•Cartilaginous neurocranium (chondrocranium) – skull base•Membranous neurocranium – cranial vault
Cartilaginous Neurocranium – Skull Base
Sphenooccipital synchondrosis•site of AP cranial base growth until ~ 20 yo
From Larsen, 1997
Achondroplasia•Premature closure of primary growth plates•Sphenooccipital synchondrosis - AP short cranial base, moon-shaped profile•Autosomal dominant; most common form of dwarfism (1/26,000 live births)
www.jrn.columbia.edu/cns/ 2002-02-22/syndication/
www.bio.psu.edu/faculty/strauss/ anatomy/skel/fetal.htm
Cartilaginous Neurocranium – Stylomastoid Foramen
•Undeveloped mastoid process
•Ring-shaped external auditory meatus
•Superficial position of stylomastoid foramen
Forceps-Assisted Delivery
www.millermedart.com/ pages/s_ob5.html
•To protect facial nerve: Avoid placing forceps immediately behind ear
From Larsen, 1997
Membranous Neurocranium – Skull Vault
•Flat bones of the skull•Sutures and fontanelles
Gardner, Gray & O’Rahilly Anatomy
•Childbirth – yielding without cracking
•Growth - expansion of cranial vault with growth of brain
Sutures and Fontanelles
www.bio.psu.edu/faculty/strauss/ anatomy/skel/fetal.htm
Anterior Fontanelle
•Palpable during 1st year
•If small – premature fusion•If bulged – increased intracranial pressure•If depressed – dehydration
•Venipuncture
Hydrocephaly
From Carlson, 1999
From Larsen, 1997
Craniosynostosis (premature fusion)Scaphocephaly Acrocephaly Crouzon syndrome
•Sagittal suture•Most common (>50%)
•Coronal suture•Aperts syndrome
•>2 sutures (coronal, sagittal)•Face, teeth, ear
Viscerocranium
•Primarily derived from neural crest cells•Membranous viscerocranium – face (below orbits) – derived from PA 1(forehead = membranous neurocranium)•Cartilaginous viscerocranium – middle ear bones, hyoid bone, laryngeal cart.
Face Formation4-8 Week Embryo – Frontal View
From Carlson, 1999
Development of Face
BONE EMBRYOLOGY FACE
Forehead
Cheek, upper jaw, lateral upper lipPhiltrum, medial upper lip
Lower jaw, lower lip, chin
Frontal
Maxilla
Premaxilla
Mandible
Frontonasal prominence
Maxillary process
Intermax. seg.Mandibular prominence
From Carlson, 1999
Initial sites of development:•Optic vesicles - laterally•Auditory vesicles – inferiorly•Nasal pits – frontal but widely separated
Eyes, Ears and Nose
Frontonasal Prominence Defect: Excessive Tissue - Frontonasal
dysplasiaFrom Carlson, 1999
•Broad nasal bridge & hypertelorism•Can be associated with other defects (e.g., tetralogy of Fallot)
Defects of the Frontonasal Prominence:
Deficient Tissue - Holoprosencephal
y
•Defective formation of prosencephalon (forebrain)•Common olfactory abnormalities•Most severe – cylcopia (fusion of op[tic primordia)
•Etiology: week 3 alcohol consumption, autosomal recessive, excessive retinoic acid, multifactorial
From Larsen, 1997
Palate Formation
From Carlson, 1999
Development of Palate
Primary Intermaxillary palate segment
Hard PalateMaxilla
Palatine Lateral palatine processes/ shelves
Soft Palate
BONE* EMBRYOLOGY PALATE
*Primary palate: premaxillary part of maxilla (houses incisors)Secondary palate: maxilla and palatine
Palate & Nasal Septum Formation
From Carlson, 1999
Face Formation, Facial Clefting
From Carlson, 1999
From Carlson, 1999
•Distinct malformations•Both are multifactorial, genetic, teratogens
Cleft Lip•Hypoplasia of maxillary process•Failure of fusion of maxillary and nasomedial processes•Most common congential malformation of H&N
Cleft Palate•Failure of fusion of palatal shelves or palatal shelf with primary palate
Cleft Lip and Cleft Palate
Cleft Palate
Cleft lip repair
www.nypchildren.org/about/ craniofacial.html
Why are babies so cute?
Somatic tissues
Neural tissues
AGE
SIZ
E
Adult size
GROWTH PATTERNS
~2 yo ~16 yo
www.liv.ac.uk/HumanAnatomy/ phd/mbchb/stroke/stk1.html
Development of Paranasal Sinuses
•Form as invaginations of nasal epithelium into diploe of cranial bone
www.bio.psu.edu/faculty/strauss/ anatomy/skel/fetal.htm
Paranasal sinuses
•Maxillary & ethmoid sinuses begun to develop in the fetus but are small at birth
•Sphenoid & frontal sinuses develop postnatally
www.iadmfr.org/oradlistimages/ image.htm
Dental Development
Permanent teeth dental formulaI,C,P,M/I,C,P,M2,1,2,3/2,1,2,3(panoramic radiograph )
Deciduous (milk) teeth dental formulaI,C,M/I,C,M2,1,2/2,1,2(lateral radiograph )
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