Evolution & Development of Face

EVOLUTION &
DEVELOPMENT OF FACE
Dr. mohd ullah khan
CIDS

CONTENTS
Evolution of face
 Introduction
 Definition
 Theories of evolution
 Concepts of evolution of human face
Development of face.
 Introduction
 Pharyngeal arches , pouches, grooves , clefts.
 Development of face
 Clinical aspects
 Conclusion
 References

INTRODUCTION
 The history of the planet Earth begins 4.6 billion years ago.
 At each age one type of life has dominated over all other forms, so
much that there is a direct relationship between climatic and geologic
condition and the dominating type of life existing.
 From the biologic point of view we see that as environment changed
there was a corresponding change in the form & structure of the
animal and plant kingdoms

 To understand the face thoroughly, it is only fair to assume that we
should start at the bottom of the ladder in the scale of life & inspect
the simplest type of face & then trace upwards through the stages of
development of face & see how it has gradually changed and molded
in form to that of modern man,

DEFINITION OF EVOLUTION
 A continuous process of change from one state, condition or form to
another.
 Stedman’s medical dictionary
 A developmental process in which an organ or organism becomes
more and more complex by differentiation of its parts; a continuous &
progressive change according to certain laws and by means of resident
forces.
 Dorland medical dictionary

THEORIES OF EVOLUTION
 Four main theories to explain the method by which species of life that
exist today have evolved from earlier simpler form:-
1. The Lamarckian theory
2. The theory of orthogenesis.
3. The theory of natural selection
4. The Mendelian theory

THE LAMARCKIAN THEORY
 Characters acquired and changes taking place during life of an
organism are inherited after the acquired character and changes have
persisted for a long time.
 They are due to change in environment and to the concerned effects of
use and disuse.
 E.g. giraffes with long necks

THEORIES OF ORTHOGENESIS(DEVELOPMENT
IN STRAIGHT LINE)
 Put forth by Haldane & Julian Huxley
 They considered that evolution proceeds in any particular direction, not
because of any advantages gained by the race or because of direct
molding effect by the surrounding, but because of some inner urge,
some necessity for the hereditary constitution to change in just that
particular way.

NATURAL SELECTION OR SURVIVAL OF
THE FITTEST
 Charles Darwin propounded this theory of organic evolution.
 This theory assumes that every life on earth was developed from
previous form.

 He attributed changes in living organism to the action of natural
selection and in many instances to the effect of use and disuse.

This theory can be summarized as:
1. Struggle for existence
2. Natural selection
3. Heredity
4. Survival of the fittest.

MENDEL’S LAW OF INHERITANCE
 Mendel discovered the fact of segregation o dissociation of characters
from each other in the course of formation of germ cell.
 His research work was on edible pea.

AUSTRALOPITHECUS AFRICANS
 3-3.5 million years ago
 Cranial capacity—500cc
 Size of cranium & portions closely resembles that of chimpanzees.
 Head– dolichocephalic
 Facial profile convex
 Dental feature are intermediate between those of apes and modern
man.

AUSTRALOPITHECUS ROBUSTUS
 2.0-1.0 million years ago
 More sturdier
 Cheek bone projecting forward
 Lower jaw is very large
 His degree of prognathism is present
 Back teeth are twice larger than the expected hominid size.

AUSTRALOPITHECUS BOSIEI
 Cranial capacity 600cc
 Tool maker and food gatherers
 They could express and communicate simple ideas with sound
 Face– long and broad
 Facial & zygomatic portions of maxilla are large.

HOMO HABILIS
 Cranial capacity—600-650cc
 Associated with stone tools
 Greater body size
 Dental reduction orthognathy

HOMO ERECTUS
 1.8-300000 years ago
 Cranial capacity-850
 Thick cranial vault
 Size of posterior teeth are decreased and anterior were larger than
modern humans
 Upper incisors are distinctively shovel shaped

HOMO NEANDERTHALS
 150000-300000 years ago
 Ruggedly built and short stocky body
 Developed skilled stone tool technology
 Had larger brain
 Dentition as a whole is placed forward relative to the skull vault

HOMO SAPIENS
 Skull is high rounded
 Orthognathic face.
 Face is tucked under the enlarged brain case.
 Teeth is progressively reduced in size, concurrently with the reduction
in masticatory apparatus.

CONCEPT 1
 Man is one of the few truly bipedal mammals
 The designs of the toes, foot bones, arch of the foot, ankle, leg bones,
pelvis, and vertebral column all interrelate in the anatomic composite
that provides upright body stance.
 The head is in a balanced position on an upright spin.
 The arms and hands have become freed.
enlow and hans

CONCEPT 2
 Enlargement the brain of have caused a “ flexure” (bending) of the h
human cranial base.
 This relates to two key features:-
 First, the spinal cord is aligned vertically.
 Second the orbits have undergone a rotation in conjunction with frontal
lobe expansion.
enlow and hans

CONCEPT 3
 The large size of the human brain also relates to a rotation of the orbits
towards the midline. This results in a binocular arrangement of the
orbits.
enlow and hans

CONCEPT 4
 The nasal region above and the oral region below are two sides of the
same coin, that is, the palate. Reduction in nasal protrusion is
accompanied by a more or less equivalent reduction of the jaw.
enlow and hans

 Facial rotation has led to the development of the human maxillary
sinus.
 Because of its adaptation to facial rotation, the human maxilla is
uniquely rectangular, rather than rectangular like that of most other
mammals.
enlow and hans

 The human face is exceptionally wide because the brain and cranial
floor are wide.
 This also relates to the rotation of he orbits into vertical, forward facing
positions as well as to the rotation of the face as a whole into a
downward backward position.
enlow and hans

NASOMAXILLARY
CONFIGURATION
 In man it is uniquely rectangular. This is caused by a rotation of the
occlusion into a horizontal plane to adapt to the vertical rotation of the
whole midface.
enlow and hans

INTRODUCTION
 The embryonic period extends from the beginning of the fourth week till the
end of the eighth week.
 The trilaminar embryonic area differentiates as follows:
1] ectoderm
2] endoderm
3] mesoderm
 The fourth week is characterized by the differentiation of the three germ layers
and the folding of the embryo
 In the second month the organs and tissues are laid down and the embryo has
a distinct human appearance
Langman's Medical Embryology 8th edition

PHARYNGEAL ARCHES
 The most typical feature in the development of the head and neck is formed by the pharyngeal or
branchial arches.

NERVE SUPPLY

FIRST PHARYNGEAL ARCH
 Meckels’s cartilage.
 Consists of two portions:
 Dorsal:-also known as the maxillary process , giving rise to premaxilla ,maxilla, zygomatic bone and part of the temporal bone.
 Ventral:- also known as the mandibular process , which contains the MECKEL’S CARTILAGE. During further development ,
Meckel’s cartilage disappears except for two small portions at it’s dorsal end that persist and form the Incus and Malleus.

Nerve supply to the muscles of the 1st arch is provided by Mandibular branch of Trigeminal nerve.
Sensory supply of the skin of the face is provided by Ophthalmic , Maxillary and Mandibular branches of
the Trigeminal nerve.
 Muscles of the different arches do not always attach to the bony or cartilagenous components of their
own arch but sometimes migrate into surrounding regions. The origin of these muscles can be traced
,since their nerve supply is derived from the arch of origin.

SECOND PHARYNGEAL ARCH
 The cartilage of the second arch (hyoid arch)is called as REICHERT’S
CARTILAGE

THIRD PHARYNGEAL ARCH
 The cartilage of this arch produces the lower part of the body and
the greater horn of the hyoid bone.
 Muscle of this arch is the Stylopharyngeus muscle which is
innervated by the Glossopharyngeal nerve.

FOURTH AND SIXTH PHARYNGEAL ARCHES
 Cartilagenuos components of the 4th and 6th pharyngeal arches fuse
to form the thyroid, cricoid , arytenoid , corniculate and cuneiform
cartilages of the larynx.

PHARYNGEAL POUCHES
 The human embryo has five pairs of pharyngeal pouches.
 The last one of these is atypical and is considered as a part of the 4th
 First pharyngeal pouch:
It forms a stalk like diverticulum –the tubotympanic recess;
 one side of this comes in contact with the external auditary meatus
 The distal aspect of this widens in a sac like structure ,the primitive tympanic or middle ear
cavity
 The proximal part remains narrow forming auditary (eustacian )tube.
 The lining of the tympanic cavity forms the tympanic membrane or the eardrum

 Second pharyngeal pouch:
The epithelial lining forms the primordium of the palatine tonsil.
 Third pharyngeal pouch:
It is characterized by a dorsal and a ventral wing .The dorsal wing
proliferates to form the inferior parathyroid gland and the ventral wing
forms the thymus

 Fourth pharyngeal pouch:
Epithelium of the dorsal wing of this pouch forms the superior
parathyroid gland.
 Fifth pharyngeal pouch :
The 5th pouch is the last one to develop and is considered to be
a part of the 4th pouch.This pouch leads to the development of
ultimobranchial body which in future leads to the
development of thyroid gland.

PHARYNGEAL CLEFT
 The 5 week embryo is characterized by the presence of 4 pharyngeal
clefts of which only one contribute to the development of the definitive
structure of the embryo.
 The dorsal part of the 1st cleft gives rise to the external auditory meatus

CLINICAL CORRELATES
 Branchial fistulas :
When the 2nd pharyngeal arch fails to grow caudally over the 3rd and the 4th
arches , leaving remnants of the 2nd 3rd &4th clefts in contact with the
surface by a narrow canal.
 Internal branchial fistulas :
It is very rare and in this the cervical sinus is connected to the lumen of the
pharynx by a small canal which usually opens in the tonsillar region.
Langman's Medical Embryology 8th editionLangman's Medical Embryology 8th edition

DEVELOPMENT OF FACE
 DEVELOPMENT OF NOSE
 DEVELOPMENT Of NASOLACRIMAL DUCT
 DEVELOPMENT OF FACIAL MUSCLES
 DEVELOPMENT OF CHEEK
 DEVELOPMENT OF EAR
 DEVELOPMENTOF EYE
 DEVELOPMENT OF LIP

 Early development of face is dominated by the proliferation & migration of
ectomesenchyme involved in the formation of primitive nasal cavity.
 At about 28 days , localized thickening develops with in the ectoderm of the frontal
prominence, just above the opening of stomatodeum.these thickenings are NASAL
PLACODES.
 Rapid proliferation of underlying mesenchyme around the placode produce a horse
shoe shaped ridge that converts the placode into NASAL PIT.
 The lateral arm of the horseshoe is called LATERAL NASAL PROCESS & the medial arm
the MEDIAL NASAL PROCESS. Between the 2 nasal process is the depressed area
of frontonasal process

NOSE
 The nose is formed from five facial prominences the frontal prominence
gives rise to the bridge; the merged medial nasal prominences provide
the crest and tip; and the lateral nasal prominences form the sides

 Nasal pit are cut off from stomatodeum
 External nares formn and approach each other.
 Frontonasal process becomes narrower and forms nasal septum from
deeper part
 As nose become prominent external nares come to open downwards
 Established.

DEVELOPMENT OF NASOLACRIMAL DUCT
NASOLACRIMAL DUCT
Obstructed Duct - failure of duct to
canalize;
is opened surgically for tears to drain to
nasal cavity

DEVELOPMENT OF FACIAL
MUSCLES
 During 5th & 6th weeks myoblasts with in the mandible arch
begin proliferation. The muscle cells become oriented to
the sites of origin & insertion of the masticatory muscle
which they will form
 By 7th week the mandible muscle mass has begun to
differentiate into the 4 muscles of mastication
 Muscle cell migration occurs prior to the time that the
skeletal ossification centers of mandible begin to appear.

 At 7th week muscle cells with in the hyoid arch undergo
proliferation & muscle cells in occipital myotomes have begun
proliferation & anterior migration toward the floor of the
mouth to become the muscles of the tongue.
 Muscle cells of hyoid arch continue migration over the
mandible muscle mass & by 10th week have migrated up over
the face. These muscle cells forms a thin sheet as they extend
up over the face, with one group of cells extending anterior to
the ear & a 2nd group extending posterior to it. They initially
follow a path like the location of platysma muscle up the side
of the neck over the mandible.

DEVELOPMENT OF CHEEK
 In lateral part of mouth (stomatodeum) it is bounded laterally by
maxillary process and below by mandibular process.
 These process undergo progressive fusion with each other to form
cheeks.

DEVELOPMENT OF EAR
 The external ear is formed around the dorsal part of ectodermal cleft.
 The auricle, or pinna is formed from about six mesodermal thickening called tubercles or hillocks that
appears on the mandibular and hyoid arches, around the opening of the dorsal part of first ectodermal
cleft.
 Mandibular arch forms tragus.
 Hyoid arch forms rest of auricle
 The three parts of the ear-
-External
-Middle and
-Internal ,arise from separate ,diverse embryonic origins .

DEVELOPMENT OF EYE
 The light sensitive portion of the eye retina ,is the
outgrowth from the forebrain ,projecting bilaterally
as the optic vesicles which are connected to the
brain by the optic stalks, this results in a thickening
called as lens placodes.
 These placodes invaginates in it’s centre by the
development of peripheral folds .
 The optic vesicles invaginate partly to form the
double layered optic cusps and the optic stalk
becomes the optic nerve .
 The outer layer of the optic cup acquires
pigmentation to become the pigmented layer of
the retina.

DEVELOPMENT OF LIPS
 Lower lip :The mandibular processes of the two sides grow towards each
other and fuse in the midline ,they form the lower margin of the
stomatodeum .
 Upper lip :Each maxillary process now grows medially and fuses, first
with the lateral nasal process and the with the medial nasal process.

Cleft lip and palate
Classification systems

Facial clefting. A, Absence of the intermaxillary segment with hypotelorism. The maxillary
processes form the normal lateral thirds of the upper lips. Absence of prolabium, incisors,
and primary palate.
B, True midline cleft of the upper lip and philtrum with hypertelorism. The nose is normal. A
7-month-old girl with transethmoidal cephalocele and left optic nerve dysplasia (morning
glory syndrome).
C and D, Midline cleft lip is also found in association with Mohr syndrome (orofacial digital
syndrome II [OFD II]). The presence of reduplicated great toes bilaterally helps to identify
OFD II and to distinguish it from OFD I.

Facial clefting. A, Right unilateral common cleft lip and palate in a
4-day-old girl. The cleft extends into the base of a widened
nostril.
B, Bilateral common cleft lip and cleft palate with discordant
forward growth of the intermaxillary segment in a 4-year-old
boy. 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.
C and D, 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.

Facial clefting. Bilateral oblique oroocular clefts with bilateral common
cleft
lip. A, Frontal view. B, Lateral view

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

Facial clefting. Nonanatomic clefts in a 12-year-old mentally retarded girl with the syndrome of amnionic bands. Lateral view. A long,
thin band-like scar extends across the scalp and face from the temporoparietal region through the cheek and the corner of the mouth
to the lower lip. The large posterior zone of atrophic skin, absent hair, tissue
bulging, and inferior displacement of the ear indicate the site of an associated temporoparietal encephalocele. Imaging studies
showed notching and separation of teeth where the band crossed the alveolar ridge.

Median cleft face syndrome, typical facies.
A, Sedano facies type A in 3-month-old boy.
B,Sedano facies type B in 4-day-old boy.
C, Sedano facies type C in a young boy after repair of concurrent bilateral common cleft lip and palate.
D, Sedano facies type D in a 31⁄2- year-old boy.

Typical facies associated with holoprosencephaly.
Five types.
A, Facies 1: cyclopia. The complete upper lip, with a hint of a labial
tubercle in the midline, could represent either fusion of the nasomedial
processes independent of the frontonasal process or fusion of the two
maxillary processes across the midline.
B, Facies 2: ethmocephaly.
C, Facies 3: cebocephaly with synophrys (fusion of the two eyebrows
across the midline).
D, Facies 4: absent intermaxillary segment, flat nasal bridge, and
rudimentary alae nasi .
E, Facies 5: hypotelorism with an intermaxillary rudiment (white
arrowhead ).

Microtia and hemifacial microsomia in two patients.
A, Microtia. The pinna is deformed. The face appears normal.
B, Hemifacial microsomia. The line formed by the two palpebral fissures and the line formed by the
mouth converge to the region of the deformed, hypoplastic pinna. The right orbit, right eye, and entire
right side of the face are asymmetrically smaller. The skin tag falls along the line between the pinna and
the mouth.

Hemifacial microsomia. Goldenhar syndrome.
•This 4-month-old girl shows a large coloboma of the medial portion of the left upper lid (between the
curved white arrows) and a whitish choristoma (straight white arrow).
•There is a second, small coloboma of the lower lid medial to the choristoma.

•Treacher Collins syndrome in an 8-year-old boy.
• Three-dimensional CT of the skin surface. A to D, Malformed
pinnae bilaterally, an antimongoloid slant of the transverse
orbital axis, malar hypoplasia with deficient lateral orbital walls
bilaterally, hypoplastic mandible with prominent antegonial
notch, narrow anterior vault, and overprojection of the central
face.

•Pierre Robin sequence in a 21⁄2-year-old boy with no
catch-up growth of the mandible.
• A and B, Lateral 3D CT of the skin surface (A) and
facial skeleton
•(B) show severe retrognathia and micrognathia.
•C, Coronalbone CT shows marked buttressing of the
mandibular condyle.
•D, Axial CT section shows a vertical orientation of the
maxillary incisors but a horizontal course of the
mandibular dentition.

 Fetal alcohol syndrome:Alcohol exposure in i.u, life . Most sensitive period of exposure is the first
trimester of pregnancy.Women having 2 – 4 drinks per day are at a risk of having smaller birth size.
 Clinical features:Microcephaly,Short palpebral fissures ,Short nose,Flat philtrum,Thin upper lip.

CONCLUSION
 JUST AS THE CLINICIAN NEEDS THE MEDICAL HISTORY TO MAKE A
LOGICAL DIAGNOSIS, SO TOO THE GROWTH AND DEVELOPMENT OF
FACE IS ESSENTIAL FOR A LOGICAL EXPLANATION OF ANY
STRUCTURAL AND FUNCTIONAL IMBALANCES IF IT DO OCCURS.

What matters most is how you see yourself …

-enlow and hans
Color atlas of embryology –Ulrich drews
-Langman’s medical embryology –Sadler
--Human embryology –Inderbeer singh
--Cleft lip and craniofacial anomalies –Ann kummer
-World wide web
REFERENC
ES

Evolution & Development of Face

Evolution & Development of Face

Recommended

Recommended

More Related Content

What's hot

What's hot (20)

Viewers also liked

Viewers also liked (20)

Similar to Evolution & Development of Face

Similar to Evolution & Development of Face (20)

Recently uploaded

Recently uploaded (20)

Evolution & Development of Face

Editor's Notes