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DEVELOPMENTALANATOMY OF THE

FACE, JAW AND NECK

O.M. OluwatosinDepartment of Surgery

By the end of this lecture, you should be able to:

Discuss the embryology of the face Relate congenital anomalies of the

face to aberrations of development Describe the surgical anatomy of facial

structures

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Six mm embryo

Eyes• Optic vesicles grow out as diverticula from forebrain• Connect with lens pit and lens vesicle from ectoderm• Optic cup develops into retina• Ectoderm:

Lacrimal gland develops from ectodermAlso epithelium of corneo-conjuctivaeNaso-lacrimal duct – thickening of ectoderm innasomaxillary groove.

• Eyelids – small fold of skin. Fuse at 3rd month until 6th

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External ears

External meatus – derived from dorsal end of first bronchialgrooveAuricle develops – 6 hillocks around margins of firstbranchial groove at (4mm embryo) mesenchyme of secondbranchial arch

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Pouch Dorsaldiverticulum

Ventraldiverticulum

1st Eustachian tube, middle earMastoid, antrum

2nd Middle ear. Tonsillar crypts,Supratonsilar fossa

3rd Inferiorparathyroid

Thymus

4th Superiorparathyroid

5th Ultimobranchial body

Lateral derivatives of pharyngeal pouchesPharyngeal grooves and pouches (opening into pharynx)separate the pharyngeal arches

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Development ofthe Tongue

Ventral derivatives ofpharyngeal pouches

Tongue – tuberculum impar, lateralrudiments. Foramen caecum. Copulaof His.

Last 3-4 occipital myotomes. Thyroidgland – thyroglossal duct.Larynx, tracheal airway

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20 mm embryo

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Thyroglossalcyst

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Arch Skeleton Muscle(mesoderm)

Artery Nerve Endoderm

1stMandibular

Maxilla, palateMandible (Meckel’scartilagedisappears) Incus,Maleus

Muscles ofmastication (masseter,temporalis,pterygoids),mylohoid, tensorpalati tympani,digastric (anteriorbelly)

InternalMaxillary (1st

aortic arch)

(Mandibularbranch ofTrigeninal)

Mucosaof anteriorof tongue

2nd

Hyoid

Stapes, stytoidprocess,Lesser cornu, upperpart of hyoid body(Reichert’sCartilage)

Stapedius, stylohyoid,digastric (posteriorbelly). Muscles offacial expression,buccinator, platysma

2nd aorticarch (mainlyrudimentaryas stapedialart. ?facialartery

Facial nerve

3rdThyro-hoid

Greater cornu lowerpart of hyoid body

Stylopharyngeus Part ofinternalcarotid

Glossopharyngeal

Mucosaof posterior1/3 of tongue,anteriorsurface ofepiglotis,valleculae

4th Thyroid cartilage,arytenoid,corniculate andcuneiformcartilages

Cricothyroid Superiorlaryngeal

5th ?cricoid (may be amodified trachealring).

Remaining laryngealmuscles

RecurrentLaryngeal

Derivatives of the arches

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Cystichygroma

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Classification ofcraniofacial anomalies

CleftsSynostosisHypoplasias

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14Clefts

Failure of mesodermal merging.Failure of fusion of facial processes

Incidence:1:600-14001:1100-2800 (Nigeria)

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Classical theory (Dursy, His)Once epithelial contact is established,mesodermal penetration completes thefusion process

Mesodermal penetration theory(Pohlmann, Veau)No free ends of facial process, there isbilaminar membrane with seamsdemarcating the major processes,mesoderm penetrates and smoothesout the seams,

Theories in theformation of clefts

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Etiological factors

Radiation: microcephaly Infection: toxoplasmosis, rubella, CMV Maternal idiosyncracies

phenylketonuria disorder, diabetes(oculoauriculovertebral OAVspectrum)

Chemicals: vitamin deficiency states,excess Vit A, isotretinoin (clefts,microsomia), thalidomide, diazepam (cleftpalate), phenytoin

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CLASSIFICATION OFCLEFTS

American cleft palateassociation

Tessier

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Clefts: types and nomenclature

Completeunilateral cleftof primarypalate:nose,lip, gingiva, premaxilla

Cleft ofsecondarypalate: hard and softpalate,uvula

Point of division:Foramen incissura

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Unoperated cleft lip

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Tessier’sclassification

of clefts

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22Clefts: treatmentType of cleft Timing Method

Cleft ofprimarypalate

Rule of 10s:Age=10 weeksWt =10 Ib,Hb =10 G/dl

Rotationadvancementflap repair(Millard)

Cleft ofsecondarypalate

Age=6 months Langenbeck’sAdvancement flapFurlow

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Hypoplasia

Van derMuelen

classification

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Frontosphenoidal dysplasia

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Frontal dysplasia

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Craniosynostosis:pathogenesis

Abnormal tensile forcestransmitted to the dura from ananomalous cranial base throughkey ligamentous attachments

Fetal head constraints

Sutural abnormality

Shunt decompression ofhydrocephalus

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Craniosynostoses

Trigonocephaly Triangular Metopic

Scaphocephaly Boat shaped Sagittal

Turricephaly Skull height Basal

Oxycephaly Pointed head Coronal

Skull shape Abnormally closedsuture

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Scaphocephaly

Turricephaly

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Metopic synostosis

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Craniosynostosis:functional problems

Intracranial hypertension Visual impairment Neuropsychiatric disorders

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Medialization of the two orbits usingoriginal Tessier procedure

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The face: sensory nerve supply

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Remember!! Trigeminalnerve also supplies themuscles of mastication