Development of Face & Abnormalities of Face

รศ.ดร.จริยา อ าคา เวลบาทAssoc Professor Dr Jariya Umka Welbat

Department of Anatomy

Faculty of Medicine, KKU

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References:

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During week 3 of embryonic development, an oropharyngeal membrane initially appears at the site of the future face. It is comprised of ectoderm and endoderm – externally and internally, respectively.During the 4th week, the oropharyngeal membrane begins to break down in order to become the future oral cavity, and sits at the beginning of the digestive tract.

Development of the Face

The five primordial appear around the stomodeum or primitive mouth early in the fourth week.

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The frontonasal prominence (local swelling), formed by the proliferation of mesenchyme ventral to the forebrain, constitutes the cranial boundary of the stomodeum.

The paired maxillary prominences of the first brachial arch from the lateral boundaries, or discs, of the stomodeum.

The paired mandibular prominences of the same arch constitute the caudal boundary of the stomodeum.

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Mesenchyme proliferates at the margins of these placodes, producing horse-shaped elevations, the sides of which are called the medial and lateral nasal prominences (swelling).

The nasal placodes now lie in depressions called nasal pits.

The maxillary prominences enlarge owing to the proliferation of mesenchyme and grow medially toward each other and the medial nasal prominence.

The medial migration of the maxillary prominences moves the medial nasal prominences toward the medial plane and each other.

The development of the face occurs mainly between the fourth and eighth weeks

By the end of the fourth week, bilateral oval thickenings of the surface ectoderm, called nasal placodes, have developed on each side of the inferior part of the frontonasal prominence.

Lower jaw and lip form first.

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Each lateral nasal prominence is separated from the maxillary prominence by cleft, or furrow, called he nasolacrimal groove.

By the end of the fifth week, the auricles of the external ears have begun to develop.

Each maxillary prominence has emerged with the lateral nasal prominence along the line of the nasolacrimal groove.

This establishes continuity between the side of the nose (formed by the lateral nasal prominence) and the cheek region (formed by the maxillary prominence).

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During the sixth and seventh weeks, the medial nasal prominences merge with each other and the maxillary prominences.

As the medial nasal prominences merge with each other, they form an intermaxillary segment.

This segment give rise to (1) the medial portion or philtrum of the lip, (2) the premaxillary part of the maxilla and its associated gigiva (gum), and (3) the primary palate.

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Prominence Derivatives

FrontonasalForehead, bridge of nose, medial and lateral nasal prominences

Medial nasalPhiltrum, primary palate, upper 4 incisors and associated jaw

Lateral nasal Sides of the nose

Maxillary (1st pharyngeal arch)Cheeks, lateral upper lip, secondary palate, lateral upper jaw

Mandibular (1st pharyngeal arch) Lower lip and jaw

Pharyngeal arches

Ectoderm

Mesenchyme core: artery, nerve & cartilage

◦ Original mesenchyme

From mesoderm in 3rd week: skeletal, musculature vascular endothelium

◦ 4th week neural crest cells: mesenchyme in the head and neck

Differentiates and produces the prominences of the first arch

Endoderm

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First or Mandibular Arch

Skeleton◦ Malleus and incus

Muscles: from 4th Somitomere◦ Muscles of mastication (e.g. masseter)

Nerve: Trigeminal (V) Aortic Arch: Maxillary Artery 1st Pharyngeal Pouch: Auditory tube (eustachian

tube) and tympanic cavity (distal end) 1st Pharyngeal Groove: External auditory meatus

(exterior ear opening)

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Skeleton◦ Stapes◦ Styloid process◦ Lesser horn of the hyoid bone

Muscles: from 6th Somitomere◦ Muscles of facial expression

Nerve: Facial (VII) 2nd Aortic Arch: Hyoid artery, Stapedius artery 2nd Pharyngeal Pouch◦ Suprstonsilar fossa: component of the palatine tonsils

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Second or Hyoid Arch

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Excess tissue in frontonasal prominence: Frontonasal Dysplasia

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➢ Broad nasal bridge, hypertelorism, cleft nose, median cleft lip.

➢ Ocular (orbital) hypertelorism increase in the interorbital distance.

➢ Can be associated with other defects (e.g. tetralogy of Fallot in Heart).

Excess tissue in frontonasal prominence: Frontonasal Dysplasia

Mediancleft lip and bifid nose

Bifid nose results when the medial nasal prominences do not merge completely; the nostrils are widely separated and the nasal bridge is bifid. In mild forms of bifid nose, a small groove is present in the tip of the nose.

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Absence of intermaxillary process

Absence of the intermaxillarysegment with hypotelorism. The midline rectangular defect indicates the site of the deficient intermaxillary segment with absent prolabium, incisors, and primary palate. There was consequent clefting of the secondary palate. Absent intermaxillary segment with hypotelorism signifies a high likelihood of holoprosencephaly.

http://imaging.consult.com/chapter/S1933-0332%2808%2973604-8#facial_clefts

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Facial clefts: median cleft lip and median cleft face

http://imaging.consult.com/imageSearch?

Deranged development of the frontonasal process and/or failure of adjacent processes to merge successfully results in a coherent series of malformations. Insufficiency of the frontonasal and medial nasal processes may result in hypoplasia or absence of the nose and intermaxillary segment, with a roughly rectangular defect in the middle one third of the upper lip, absence of the incisors, absence of the primary palate with a cleft in the secondary palate, and hypotelorism. This is one common manifestation of holoprosencephaly.

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Median cleft lip

http://health.allrefer.com/health/cleft-palate-resources-cleft-lip-repair-series-4.html

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True midline cleft of the upper lip and philtrum with hypertelorism. True midline cleft lip signifies the high likelikhood of midline craniofaciocerebraland optic dysraphism(incomplete closure of a raphe; defective fusion, particularly of the neural tube).

http://imaging.consult.com/chapter/S1933-0332%2808%2973604-8#facial_clefts

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Right unilateral common cleft lip and palate. The cleft extends into the base of a widened nostril. The intermaxillary segment is distorted.

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https://www.google.com/search?biw=1920&bih=969&tbm=isch&sa=1&ei=4l2lXZqHNcv1rQHm1aKADw&q=biilateral+cleft+lip&oq=biilateral+cleft+lip&gs_l=img.12...644471.651822..687139...1.0..0.88.782.10......0....1..gws-wiz-img.wnpSQzd9Uxc&ved=0ahUKEwiagNzeyJ3lAhXLeisKHeaqCPAQ4dUDCAc#imgdii=TQlJ8F5M5nK9xM:&imgrc=ZYXl1lNFV4OFlM:

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Bilateral common cleft lip and cleft palate with discordant forward growth of the intermaxillary segment.

The normal canthi, alae nasi, and lateral thirds of the lip and jaw indicate normal formation and merging of the maxillary and nasolateral processes.

The abortive prolabium, premaxillary segment, and central incisors attach to the vomer and project well anterior to their expected position, because failure to merge the facial processes led to discordant growth of the maxillary and intermaxillary segments.

Bilateral common cleft lip and palate prior to (C) and

following (D) surgical repair. There is near-symmetric

restoration of the nose and upper lip, with some residual distortion caused by scar.

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Oblique facial clefts

http://imaging.consult.com/imageSearch?

❖ Obliques facial clefts

are produced by failure

of the maxillary

prominence to merge

with its corresponding

lateral nasal prominence.

❖When this occurs, the

nasolacrimal duct is

usually exposed to the surface

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Discordant growth of the two divided processes may then result inoffset of the premaxillary segment from the maxillary segment, awidened nostril, a depressed ala nasi, and an anomalous nasalseptum. Failure to merge the nasolateral process with the maxillaryprocess results in an oblique facial cleft extending from the innercanthus of the eye into the nose

Facial clefting. Bilateral oblique oroocular clefts with bilateral common cleft lip.

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This cleft may occur in association with bilateral common cleft lip and/or palate. Failure to merge the maxillary with the mandibular process, unilaterally or bilaterally, results in a transverse facial cleft, also designated “wolf mouth” or macrostomia.

Facial clefting. Unilateral transverse facial cleft and macrostomia in an infant girl.

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Cebocephaly: a monkeylike deformity of the head, with the eyes close together and the nose defective.

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Development of Nasal cavity

รศ.ดร.จริยา อ าคา เวลบาทAssoc Professor Dr Jariya Umka Welbat

Department of Anatomy

Faculty of Medicine, KKU

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Nasal cavity

6th week nasal pit: nasal sacThe beginning of 6th week to the end of 7th week nasal fin, oronasal membrane7th week primitive choaca, primary palate

PalatePrimary palate7th week Primary palate: intermaxillary process

premaxillary part8th & 9th week Secondary palatemaxillary process: palatine

self or lateral palatine process9th week – 12th weekpalatine selves + primary

palate = secondary palate

Nasal septum & concha

Nasal septum: ectoderm & mesoderm of frontonasal & medial nasal processesdefinitive choanaNasal concha: superior, middle and inferior

Maxillary sinuses:nasal sac ➔ are small at birth.

These sinuses grow slowly until puberty and are not fully developed until all the permanent teeth have erupted in early adulthood.

Paranasalair sinus

Paranasalair sinus

- The ethmoidal sinuses (middle meatus) small before the age of 2 years and do not begin to grow rapidly until 6 to 8 years of age. At approximately 2 years of age, the two most anterior ethmoidal cells grow into the frontal bone, forming a frontal sinus on each side. Usually the frontal sinuses are visible in radiographs by the 7th year.

- Sphenoidal sinuses are present at birth.- The most posterior ethmoidal cells grow into the sphenoid bone at approximately 2 years of age, forming two sphenoidal sinuses.

Paranasalair sinus

Growth of the paranasal sinuses is important in altering the size and shape of the face during infancy and childhood and in adding resonance to the voice during adolescence.

Olfactory area

5th weekNasal placode: 1˚neurosensory cell➔ Olfactory epithelium

cribiform plate

6th-16th weeknasal pit ➔ respiratory epithelium

1˚neurosensory cell

2˚neurosensory cell in olfactory bulb

Axon of 2˚neurosensory cell: olfactory tract

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Vomeronasal organ (of Jacobson)

Atavistic remnants in human, vomeronasal organ are well developed

in mammals and are considered to be olfactory chemoreceptor

organs that aid the sense of smell, reproduction and feeding.

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