PEDOLOGIC ANATOMY

Chetan BasnetBDS IV year

Roll no. 02

Introduction Fetal Growth Changes General Post Natal changes In Dimensions &

Proportions Oral Features Of Neonates External Features Of Newly Born Child Reflexes present at Birth Summary References

Contents

A child may appear as a MINIATURE ADULT to a LAYMAN but the detail anatomy reveals that he/she is completely different from an adult. The growth and development seems MIRACLE in growing child.These changes vary progressively till puberty after which permanent features are established.

NOTE:-the comparative knowledge of adult and child is

necessary to be known so as to recognize or diagnose developing characteristics of a child which may be mistaken for an Abnormality or Pathologic condition.

Fetal Growth Changes

Head flexed, neck longer and clearly defined Development of face with upper lip and nostrils The palate incompletely formed Enamel organs formed from dental lamina. The external ears and eyelids are developing and limbs

are forming. Skeletal and visceral tissue begins to form. Kidney begins to form with tubules. The back bone and vertebral canal form small buds that

will develop inner and upper extremities. Heart forms , starts functioning and body system

begins to form.

End of First Month

Eyes are far apart with eyelids fused and nose flat. Ossification begins and limbs becomes distinct as upper

and lower. Digits are well formed. Major blood vessels forms. Internal organs continue to develop.

End of Second Month

Eyes fully develop but eyelids still fused. Bridge of nose develop and external ears

are formed. Ossification continues, nails develop. Head flexion increases and neck becomes

proportionately larger. The umbilical protrusion of the gut is

reduced with a proportionate abdominal volume.

Heart beat is detectable.

End of Third Month

Head is large in proportion to rest of the body. Face takes on human features and hair appear on

head. Skin is bright pink. Many bones are ossified and joints begins to form with

continued development of the body systems. The eyes have moved forward to anterior position but are

still wide apart. The external ear is on the side of the head and no longer on upper part of the neck.

End of Fourth Month

Head is less disproportionate to the rest of the body. Fine lanugo hair covers the body. Rapid development of body systems takes place. Skin is bright pink and sebaceous glands become

active forming a cheesy covering over the skin. Fetal movement called “quickening” can be seen.

End of Fifth Month

Head becomes smaller but still less disproportionate to

the rest of the body. Eyelids separate and eyelashes form. Skin is wrinkled and pink. Increase in growth of sebaceous and cutaneous tissue

occur.

End of Six Months

Head and body becomes more proportionate . Skin is wrinkled and pink. Eyebrow hair and eyelashes are developed. Eyelid separate and the papillary membrane separate. Body is more plump.

End of Seven Month

Sub-cutaneous fat deposition takes place. Skin is less wrinkled. Testes descends to scrotum. Bones of head are soft. There is progressive loss of lanugo, except of eyelid

eyebrows and scalp. The shape of body is more infantile. The thorax and abdomen broaden relative to head. The umbilicus is gradually centrally located. Chances of survival is much greater at this

period.

End of Eight Month

Additional subcutaneous fat accumulates. Lanugo sheds. Nails extend to tip of finger and even beyond.

End of Nine Month

General Post Natal changes in Dimensions and Proportions

The neonate has 270 bones as

compared to adult (206). Skull bones in neonate are 45 due to

incomplete ossification and in adult 22. The frontal bone at birth is in two halves

which fuses at 2 yrs.

Neonatal Skeleton

There are two parietal bones. The occipital bone at birth consists of four pieces, which

fuse by 3-4 yrs. of life. The sphenoid bone is made up of three parts at birth,

which fuse during the first year. Sinuses do not develop in the sphenoid till the 5th year.

1. the body , 2. the lesser and 3. the greater wings

Mastoid process is absent in the neonate thus the stylomastoid foramen lies superficial.

…

The body proportions are a result of the differential rates of

growth of the cephalic and caudal ends. Massive changes in the body proportion occur from the fetal life to adulthood.

Mid point: The mid point of the stature of a two month old embryo is at chest, close to chin.

At Birth: This may shift to just above the umbilicus. In Adult: It is at the pubic-symphysis region.

Body Proportions

• The length of the head doubles by adulthood, but the rest of the body grows still more, hence at birth 22% of the body area is covered by the head.

• This decreases to 13% at 12 yrs. and 10% in an adult.• There is an axis of increased growth extending from the head towards the

feet. This increased growth is the cephalo-caudal gradient.• In a new born child the height is measured using measuring tape in a laying

position and referred as LENGTH.[ 40-45 cm]

The new born is usually kept in supine posture but can

be literally folded to its most comfortable position i.e. the posture simulating the fetal posture of partial flexion.

Mild lordosis and protuberance of the abdomen is a common finding at 2-3 yrs of age but disappears by 4 yrs.

Posture

The neck is relatively short at birth and its muscles are

not developed for supporting the head. Functional development of the muscles begins after 2

mnths.

The Neck

The girth of the chest at birth is smaller then the head

circumference. It becomes equal by 2 yrs and by 15 yrs its ratio

becomes 3 : 2 The final ratio is 5 : 3 The chest is rounded in newborn.

The Chest

The umbilicus of new born is shed off around 12- 15

day. The umbilicus is everted and in some cases umbilical

hernia may be present. At this stage abdomen is quite protuberant but soft. Circumference of abdomen is equal to the chest until

two yrs BUT after 2 yrs abdominal circumference is less than the chest.

Abdomen

At Birth:

legs are short , arms long Arms:

birth – 2 yrs : length increase by 6.75% At 8 yrs – 50% longer than at 2 yrs By 16- 18 yrs – slow growth, increase development takes place.

Legs: at birth: short & curved Birth – 2 yrs: length increase by 40% [a lot of fat deposits on

medial aspect of foot giving flat foot appearance] 6 yrs: straight, the knock knee and flat foot gets corrected 8yrs: 50% longer than at 2 yrs Adolescence: 4 times longer than birth Early maturer: shorter legs than the late maturer

Extremities

The skeletal portion of craniofacial complex develops as a blend

of morphogenesis of primary skull components.1. The Neurocranium : it consists of two parts:

a) The desmocranium: comprise the vault of skull or clavarium. It protects the brain and is formed of intramembranous bone.

b) The Chondrocranium: forms the base of skull which ossifies as an endochondral bone.

2. The viscerocranium : formed by the bones of facial skeleton which develop by intramembraneous ossification which is derived from brachial arches.

Changes in Craniofacial Complex

This changes can be appreciated even in IUL. 3 mnth – Birth:

the entire cranium becomes longer and wider in its relation to height. At Birth:

• Craniofacial skeleton undergoes changes between 30%-60% of its total growth.

• head makes up about a greater part of total body length whereas in adult accounts for

about one- eighth of total body height.

Dimensional changes in Craniofacial Skeleton

After birth:

Size of cerebral cranium increase by about 50% while the facial skeleton will grow more than twice the original size.

By 4 years:This growth is completed. Cranial circumference increase from about 33cm [ birth] - 50cm [at 3 yrs]. After which it only increase by 6cm.

After 4yrs +:Facial skeleton increases in all direction.

NOTE:-Due to above craniofacial changes features of head and face are observed to be different at different ages.

…..

At Birth:

The head circumference is around 35 cm. 6 months:

It increases by 44 cm. At 1 yrs:

Head circumference may be more then chest circumference. A total 4 inches increase takes place. 1+ year:

1 inches increment occurs between 1-2 yrs. At 10 yrs:

95% of total head growth completes with the width of head completed by 3yrs while the length of head completes by 17-18 yrs.

Head

Fontanel is one of the space, covered by

membrane between the bones of the fetal or young skull.

They bridge the gap between the bones that limit them.

They are made up of:a) Dura materb) Primitive periosteum &c) Aponeurosis form inside

Fontanelles

Fontanells present at Birth:1. Anterior Fontanelle : between two parietal bone & the frontal

bone.2. Posterior Fontanelle : between two prietal bone and the

occipital bone3. Sphenoid Fontanelle : between the frontal, parietal, temporal,

sphenoid bone.4. Mastoid Fontanelle : between parietal, occipital and the

temporal bone

…

Clinical Importance of Fontanelle : Enables the fetal skull to modify its size and shape as it

passes through the birth canal and permits rapid growth of brain during infancy.

Helps the physician to gauze degree of brain development by their state of closure.

Anterior Fontanelle serves as landmark for withdrawal of blood for analysis from superior sagital sinus.

Depressed levels of Fontanelle suggests dehydration and increased level indicate increase in Intra-cranial pressure.

Closure of Fontanelle : a) Anterior Fontanelle [Frontal] : 18-24 mnths after birth.b) Posterior Fontanelle [occipital]: 2 mnths after birthc) Antero-lateral Fontanelle [Sphenoid] : 3 mnths after

birth (paired)d) Postero-lateral Fontanelle [mastoid]: begins to close 1-

2 mnths after birth, closed completely by 12 mnths (paired)

Sutures of cranium1. Coronal Suture: between the frontal and parietal bone. Closes by 24-

35 yrs 2. Sagittal suture: between two parietal bone. Closes by 22-30 yrs of

age.3. Lambdoidal Suture: Between two parietal and occipital bone. Closes

by 29 yrs of age.4. Squamous Sutures and Lateral antero-posterior Sutures:

between the squamous portion of the temporal and parietal bone. The squamous suture closes late in life.

Face

At birth , lower third and the middle third of the face are underdeveloped due to the absence of the teeth.

The fore-head is high and bulging. The face of the newly born baby is round and flat. The eye dominate and owing to the absence of the root of the

nose, appear to be widely separated. After the onset of the puberty the forehead flattens and widens,

lips thicken and face acquires an oval shape, mainly due to growth of jaws.

The child convex profile is straightened out, owing to the more anterior position of the jaws.

Naso-Maxillary Complex

The maxilla develops in the membranous tissue at the end of the sixth fetal week.

The maxilla is attached to the neurocranium directly with the frontomaxillary sutures and indirectly by means of various other facial structures such as the nasal, lacrimal and ethmoid bones, nasal septum including vomer, palatine bones and zygomatic arch.

Most of the structures mentioned above are joined together in an edged – edge fashion.

During the early phase of fetal development the sagittal interrelation of the jaws is characterised by Mandibular protrusion, which is gradually reversed.

At birth the maxilla is placed more anteriorly giving Class II relationship of the jaws.

… Later in course of post-natal development, both maxilla

and mandible with their associated soft tissues grow forward and downward and establish a normal Class I relationship.

Maxillary sinus at birth are not well developed and present like slits.

Development of orbital cavities is practically complete at birth.

Nasal cavity is located between the two orbits of the eyes and its floor is roughly at level with their bottoms.

The alveolar process can only be faintly discerned and the palate has a weak transversal curvature.

The maxillary body is almost entirely filled with the developing teeth.

Mandible Although still seperated by symphisis in the mid-line, the

two halves of the mandible fuse into a single bone by the age of 1-2 yrs.

At birth: The two rami are short. Condylar development is minimal. A thin line of fibrocartilage and connective tissue exists at the midline

of the symphisis to separate the right and left mandibular bodies. The symphysial cartilage is replaced by bone [ between 4 mnths of

age –end of the 1 year]. Growth is quite general, with all surface showing bone apposition,

esp. at the alveolar border, distal and superior surface of the ramus, condyle, lower border and lateral surface of the mandible.

The alveolar process and the muscles are poorly developed at his age, so that its basal arch mainly determines the shape of the mandible in the neonate.

At birth the structure of mandible is shell like with 10 alveolar sockets for developing tooth gum.

Of all the facial bones, the mandible shows not only the largest amount of post-natal growth, but also the largest individual variation in morphology.

The position of the mandibular foramen changes by remodelling , to a more superior position from the occlusal plane as the child matures into the adult.

The foramen is below the occlusal plane in a very young child, slightly at occlusal plane at the period of primary dentition. It averages 7mm above the occlusal plane in an adult.

Angle of mandible is more obtuse in young children. Mental foramen is placed very close to the border of the

mandible in young children.

TemperoMandibular Joint [TMJ]

Three phases of development are seen in the intrauterine life period .

- Valasco Merida et all. 1999

I. Blastemic Stage:7-8 wks of sevelopment coresponding to the

organization of condyle, articular disc and capsuleII. Cavitation stage:

9-11 wks of development corresponding to the initial formation of inferior joint cavity and then start of condylar chondrogenesis.

III. Maturation stage:after 12 wks of development

Post -natal Changes in TMJ

At birth the articular disc is flat and develops an accentuated S- shaped profile as the articular tubercle develops.

Condylar cartilage is approx. 1.5 mm thick at birth, but soon thins down to 0.5 mm. By 20-30 yrs of life it is completely replaced by endo-chondral ossification.

Mandibular condyle grows in a constant posterior, superior and lateral direction and attains a mature contour by late mixed dentition period.

Oral features of the Neonate

Oral features of the

Neonate The edentulous arches of a child varies from an

edentulous adults. The alveolar process of an infant are called gumpads,

which are firm and pink structures with a definite form.

Gumpads

Each gumpad is divided into 10 segments by a transverse grooves.

The groves between the deciduous first molar and canine are prominent and called lateral sulci.

Upper Gumpad

It is a horse shoe shaped and shows:

Gingival Groove: separate gumpad from palate.

Dental Groove:originates in incisive papillae region and extends backwards to touch the gingival groove in the canine region and then laterally to end in the molar region.

Lateral Sulcus : is a deepened groove separating canine and deciduous first molar segments.

Lower Gumpad

Differs from upper. Is “U” shaped, with its

anterior portion everted labially.

Gingival groove- that demarcates the lingual extent of gumpads.

Dental groove - running from the mandible backwards, laterally to join the gingival groove in the canine region.

Lateral sulcus- deepened groove separating the canine and deciduous first molar segments.

Relationship of Gumpads

At rest gumpads are separated by the tongue lying over the lower gumpad.

There is no definite antero-posterior relationship of the gumpads on occlusion, but lower gumpad being smaller, the lateral sulcus of the lower gumpads lies distal to that of the upper.

There is no variable overjet with contact only in the first molar segments.

During function the mandibular movements at this stage are

mainly vertical and to a very small extent in the antero-posterior direction. Lateral movement are absent.

During the early phase of fetal development the sagittal interrelationship of the jaws is characterized by mandibular protusion which is gradually reversed.

At birth lower jaw is situated posteriorly. This relationship has some significances i.e. disturbed post-natal forward growth of development may result in malocclusion

Growth of Gumpads

At birth the width of gumpads are inadequate to accommodate all the incisors.

The growth is rapid in first year after birth Growth is more in transverse direction and in the labio-

lingual direction. Due to the growth the segments of each gumpads

become prominent. Eruption of deciduous teeth commence at 6 mnths of

age.

Tongue

It is comparatively large in relation to the small mouth. Then tongue is flat, thin and blunt tipped, probably due

to short frenum. The tongue at this stage performs only one function,

i.e. acts as a piston while suckling.

Tonsils & Adenoids

At birth:tonsils and adenoids are small in size. Clusters of yellow

and white follicles with erythematous border may appear initially. A few days after birth these may regress.

First few months:the growth of tonsils and adenoids takes place as

lymphoid tissue starts proliferating and establishing function. This growth is more in presence of infection.

6 mnths – 2 yrs:Max. growth occurs as the primary physiological enlargement.

At 6 yrs:the next hypertrophy, after a period of quiescence, occurs especially when the child is exposed to infection at school. This is secondary physiological enlargement.

At puberty:the regression and atrophy of naso-pharyngeal lymphoid tissue finally occurs by the time child attains puberty.

Buccal Pad of Fat

[Corpus Adiposum / Bichat’s Fat Pad]

It is a child reserve of energy. It is nothing but the child cheek prominence giving a chubby appearance. It is formed of a firm encapsulated mass of fat lying between the subcutaneous fat and the muscle of the cheek.

Its exact role in suckling is not known. It probably plays no role in suckling, but it has been found to regress once suckling has ceased

EXTERNAL FEATURES OF

NEWLY BORN CHILD

The skin of the neonate is often reddish. A child may have an appearance of CYANOSIS due to

thin skin and high hemoglobin content of blood even when CO2 is high

A deep red purplish appearance may be result of transient anoxia resulting from closed glottis prior to vigorous cry.

Deep red skin with fine soft immature lanugo hair is a characteristics of premature infants.

Post-term infants may show whitish, peeling, parchment like skin.

Skin

Size:

The eye of the neonate are small at birth, the size being one third of the adult size. Maximal growth occurs in 1 year and continues rapidly decelerating rate till 3 yrs and further slows down till puberty. Cornea:

At birth, cornea is relatively more and nearly fills the palpebral fissures. It reaches an adult size by 2yrs. After which the posterior aspect of the eyes grows giving ball its final spherical shape. The Lens:

it is more or less spherical with greater refracting power.

Eyes

The Fundus: It is less pigmented than adults. It acqiure its adult form by 4-

6 mnths. The Retina:

It has fine peppery mottling. The peripheral retina appears pale or greyish since peripheral vasculature is immature.

…

The nose of the neonate is small and flat with narrow nostrils. The bridge of the nose is depressed. Maximal growth of the nasal cartilage occurs till puberty,

after which it attains its final form. The hair around the nose become thicker around the puberty.

Nose

The lips of new born is reddish pink, soft and supple. The midline of upper lip has a small projections, the labial tubercle,

which is said to disappear after cessation of suckling. It may undergo slow transformation to form the transition zone

between the outer and inner aspect after one year.

Lips

The ears of child are almost developed. The external auditory canal is short, straight and full of

secretion. The tympanic membrane has a dull grey translucency

and the structures of the middle ear can be easily studied through it.

Ear

REFLEXES PRESENT AT BIRTH

Reflexes Present At Birth

Reflex is an involuntary, or an automatic, action that your body does in response to something, without even having to think about it.The various reflexes are:1. General Body Reflexes2. Facial Reflexes3. Oral Reflexes

General Body Reflexes1. Moro Reflex2. Startle reflex3. Palmar reflex/ Grasp Reflex4. Walking/ stepping Reflex5. Limb placement reflex6. Asymmetric Tonic Reflex7. Babiniski’s Reflex8. Parachute Reflex9. Landau Reflex10. Tendon Reflex11. Abdominal Reflex

Moro ReflexAny sudden movement of the neck initiates this reflex.

A satisfactory way of eliciting the reflex is to pull the baby half way to a sitting position from the supine and suddenly let the head fall back to a short distance.This reflex consists of a rapid abduction and extension of the arms with the opening of hands. The arms come together as in an embrace.

Clinical Importance:o This reflex gives an indication of muscles tone.o The response may be asymmetrical if muscle tone is

unequal on the two sides, or if there is a weakness of arm or an injury o the humerus or clavicle

o This reflex usually disappear in 2-3 months.

Startle ReflexIt is similar to Moro reflex, but it is initiated by a

sudden noise or any stimulus. In this reflex, the elbows are flexed and the hands are remained closed, there is less of embrace, outward and inward movement of arms.

Palmar / Grasp Reflexo When the baby palm is stimulated, the hand closes.

There is also corresponding Planter Reflex. o Both normally disappear after 24 months.

Clinical Significance:An exceptionally strong grasp reflex may be found

in the spastic form of cerebral palsy and in Kernicterus.

It may be asymmetrical in hemiplegia and in cases of cerebral damage. It should have disappeared in 2- 3 months and persistence may indicate the spastic form of cerebral palsy.

Walking / Stepping Reflex

When the sole of the foot is pressed against the couch, the baby tries to walk. It persists as voluntary standing.

Limb Placement ReflexWhen the front of the leg below the knee, or the arm

below the elbow is brought in contact with the edge of table, the child lifts the limb over the edge.

Asymmetric Tonic Reflex

When the baby is a rest and not crying, he lies at intervals with his head on one side, the arm extended to the same side, and often flexion of the contralateral knee. This reflex normally disappears after 2/3 months, but may persists in spastic children.

Babiniski’s ReflexStroking of lateral surface of planter surface of the foot

from the heel to the toe results in flexion of the toe.

Parachute ReflexIt appears at about 6-9 months and persists there after.

This reflex is elicited by holding the child in ventro suspension and suddenly lowering him in the couch. The arms extended as a defensive reaction. In children with cerebral palsy, the reflex may be absent or abnormal. It would be asymmetrical in spastic hemipalgia.

Landau ReflexIt is seen in vertical suspension, with the head, spine

and legs extended. If the head is flexed, the hips , knees and the elbows also flex. It is normally present from 3 months and is difficult to elicit after 1 year.• Absence of reflex occurs in Hypotonia, hypertonia, or

severe mental abnormality.

Tendon ReflexThey are present in neonate. They are of great value

for the diagnosis of cerebral palsy.• In spastic children the tendon reflex are exaggerated.

Facial Reflexes

Nasal ReflexStimulation of the face or nasal cavity with water or

local irritants produce apnea in neonates. Breathing stops in expiration with laryngeal closure and infants exhibit bradycardia and lowering the cardiac output.

Blood flow to the skin splanchnic areas, muscles and kidney decrease, whereas flow to the heart and brain is protected. Midwives have for many years blows on the face of neonates to induce the first breathe.

Blink ReflexVarious stimuli provoke blinking. Where the child is

awake or asleep, pupils of the eye react to change in intensity of light.

Corneal ReflexIt consists of blinking when the cornea is touched. The

satisfactory demonstration of these reflex shows that the stimulus, whether sound light or touch has been received, that cerebral depression is unlikely, and that appropriate muscles can contract in response.

Doll’s Eye ReflexThrough a complex mechanism, infants hold fixation of faces,

movements or changing intensity of light within their visual fields. During the first week they are able to maintain these fixations against passive movement of their bodies.

Pupil ReflexesThe pupil reacts to the light but in the preterm baby

and some full term babies the duration of exposure to the light may have to be prolonged to elicit the reflex. The light used should not be bright, for a bright light will cause closure of the eyes.

ORAL REFLEXES• Rooting Reflex• Sucking Swallowing• Gag Reflex• Cry• Mastication

Rooting ReflexWhen the infants cheek contact the mother’s breast,

the baby mouth results in vigorous sucking movements resulting the baby rooting for milk. When corner of the mouth is touched, the lower lip is lowered, the tongue moves toward the point stimulated. When the finger slides away, the head turns to follow it. When the center of the upper lip is stimulated, the lips elevates.

• Onset: 28 wks IU• Well established: 32- 34 wks IU• Disappear: 3-4 months• Elicited by:

the “rooting” or “search” reflex is present in normal full term babies. When the baby cheek contacts the mother’s breast or the other parts, he “roots” for milk. It enables him to find the nipple without his being directed to it.

Sucking• Onset: 28 wks IU• Well established: 32-34 wks IU• Disappears: starting around 12 mnths• Elicited by: It is tested by introducing a finger or teat into

the mouth, when vigorous sucking will occur.

Swallowing• Onset: begins around 12 ½ wks IU life.

full swallowing and sucking established 32-36 wks of IU life

Sucking & swallowing reflexes are present in full term babies. Their absence in a full term baby would suggest a developmental defect.

Infantile Swallow:Until the primary molars erupt, infants swallow

with the jaws separated and tongue thrust forward using facial muscles (Orbiculars oris& Buccinator). This is non conditional congenital reflex.

Acquired Conginetal Reflex:After eruption of the posterior primary teeth, from the 18

months of age onwards the child tends to swallow with the teeth brought together by the masticatory muscles action, without a tongue thrust.

Gag ReflexIt is seen in 18 ½ wks. IU life. In the buccal cavity

and pharynx, the ectoderm / endoderm zone is towards the posterior third if the tongue. Touching here elicits a gag reflex, a protective reflex.

CryIt is a non conditional reflex which accounts for its lack

of individual character and is of sporadic nature. Its starts as early as 21-29 wks IU life.

MasticationIt is a conditioned reflex, learned initially by irregular

and poorly coordinated, chewing movements. The proprioceptive response of the TMJ and the periodontal ligament of the erupting dentition establishes a stabilized chewing pattern, aligned to the individual dental inter-cuspation.

Summary• Knowledge of PEDOLOGIC ANATOMY is very helpful to PEDODONTIST as it

not only serves as an adjunct in DIANOSIS but also aids in TREATMENT PLANNING.

• The knowledge of different growth spurts helps in planning treatment especially in Interceptive Orthodontics where growth can be modified or surgery is indicated. [ e.g. Cleft lip & Palate]

• The knowledge of development of motor skills and language helps to know whether development is going on proper rate or not.

• The knowledge of reflexes helps to identify whether child is developing normally or not. It also helps to know what abnormalities child may be having if reflexes are not proper.

REFERENCES

• TEXTBOOK OF PEDODONTICS- 2nd edition-Shobha Tandon

• Internet sources

Thank You