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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