Each of these arches contain: A central cartilage rod that forms the skeleton of the arch. A muscular component called branchiomere. A vascular component. A neural element.
The mental ossicles Incus and malleus Spine of sphenoid bone. Anterior ligament of malleus Spheno - mandibular ligament
Nasal septum- tongue position – palatine shelf fusion the main part of the definitive palate is formed by two shelf like outgrowths from the maxillary prominences. The palatine shelves appear at the 6 th week of development and are directed obliquely at each side of the tongue. At the 7 th week, they attain a horizontal position and fuse to form the secondary palate. The shelves also fuse with the primary palate anteriorly.
Accumulation of hyaluronic acid is the chief component of shelf elevating force. Degree of mesenchymal cell biosynthetic activity at different stages of palatal development .
Micro gnathia Glossoptosis PIERRE ROBIN Upper airway obstruction Cleft palate
Sprouty family of genes Sprouty homolog 2 Fibroblast growth factor A dosage-dependent role for Spry2 in growth and patterning during palate development Ian C. Welsh, Aaron Hagge-Greenberg, Timothy P. O’Brien*
Natural increase in palatal width…… vertical drift of posterior teeth with lateral expansion (v principle).
As a result of medial growth of the maxillary prominences, the medial nasal prominences merge both at the surface and at a deeper level- intermaxillary segment.
Facial growth involves an interrelationship between all componenent parts ,hence no part is independent or selfcontained. Growth works towards an ongoing functional and structural equilibrium
the lowest point of the zygomaticomaxillary ridge. Also called zygomaxillare . Irregular lines containing concavities directed away from the bundle bone and serving as histologic indications that resorption has taken place up to that line from the marrow side
36-38 th day mandibular ectomesenchyme interacts with mandibular epi’ b4 prim ossification. Intramembranous bone lies lateral to cart. 1 ossification centre for each half arises in 6 th week in region of bifurcation of IAN into mental, the ossification spreads dorsally n ventrally to form ramus n body. Ossificatn stops at site whr it wud be lingula. Medially it meets its feloow counter part.distally upto middle ear. Major cart disaapears. Sphenomand lig
Secondary accessory cartilages occur bet 10-14 th weeks to form head of condyle, coronoid,mental protrb Coronoid cart: fuses wit expanding intramemb ramus b4 birth Mentl:1-2 small cartilages appear n ossify in 7 th month iu in fibrous symphysial tissue Condylar cart: appear 10 th wk. this is promordium for future condyle.cart differentiate by interstitial n appositional growth. By 14 th wk, 1 st evidence of endochondral bone formtm Condyle cart imp growth centr for ramus. Condylr growth peak at puberty. 12-14 months post natally,2halves fuse into synostosis
Mand appears as single bone. Basal bone frms one unit to wic alveolar, condylar, coroniod, angular pr n chin is attached. They grow by functoinal matrx theory Teeth act as functional matrix for developmnt of alv bone Temporalis influences coroniod pr Masseter n med pt –angle Lat pt- condylar
Secondary in evolution Secondary in embryonic origin Secondary in adaptive responses to changing developments
This allows for posterior lengthening of the body and the dental arch.
The posterior development of the mandibular bony arch simultaneously proceeds into the region that was previously occupied by the ramus.
Some of the key anatomic parts that participate in the relocation and remodeling process of the ramus and corpus cannot be seen or represented in 2d headfilms . Among these is the lingual tuberosity.
It remodels mostly posteriorly with only a slight lateral shift. Becoz the bicondylar width does not increase as much as mandibular length beyond the early childhood period.
Deposition occurs on the inner side of the v and resorption on the outer surface…..the direction of movement is towards the wide end of the v…
The foramen from childhood maintains a constant position midway between the anterior and posterior borders of the ramus. The depth of the mandibular antegonial notch as an indicator of mandibular growth potential Am J Orthod Dentofacial Orthop. 1987 Feb;91(2):117-24. The depth of the mandibular antegonial notch as an indicator of mandibular growth potential. Singer CP , Mamandras AH , Hunter WS .
GONIAL ANGLE : The angle formed by the junction of the posterior and lower borders of the human lower jaw
The condyle was earlier believed to be responsible for the overall mandibular growth. Endo chon growth occurs here bcoz the pressure levels are beyond the capacity of the bone’s vascular soft tissue membrane.
Lack of mand condyle does cause growth discrepancies but cannot be concluded that it is a growth centre. Although reconstruction of bone can be done to correct the deviation; the absent muscle function cannot be restored.
Enlow’s growth prin’ : Growth of any facial or cranial part relates specificallyto other structural and geometric counterparts
The gonial angle reduces to prevent change in occlusal relationship between maxillary and mandibular arches. At birth: 180 0 Adult: 90 0
C.Gland: swelling and eversion of the lower lip C.Granu: sudden onset and progressive course terminating in chronic enlargement of the lips. :799 Peutz: development of benign hamartomatous polyps in the gastrointestinal tract and hyperpigmented macules on the lips and oral mucosa
Busulfan, Chlorambucil, Cyclophosphamide, Mercaptopurine, Methotrexate can cause clcp fetus is most vulnerable to teratogens (substances that cause birth defects) between the 3rd and 8th week after fertilization, when the organs and systems are developing. Certain drugs and other teratogens, however, can harm the fetus at any point during pregnancy. Teratogenic drugs taken before the 20th day following conception often have an all-or-nothing effect, inducing miscarriage or having no effect at all. While drugs taken after the first trimester are less likely to result in serious birth defects, these teratogens can alter the function of organs and systems resulting in more subtle impairments and developmental defect (oshman & milisola ,LLP )
GROWTH ANDDEVELOPMENTPRE-NATAL & POST-NATAL GROWTH OFMAXILLA AND MANDIBLE
CONTENTS1)Pre Natal development of Maxilla Embryonic development Meckel’s cartilage Development of palate Mech’ of palate elevation Palate remodelling2)Post Natal development of Maxilla Displacement Remodelling Growth at sutures Growth in height,wifth & length Key ridges Maxillary sinus
CONTENTS1) Pre Natal development of Mandible2) Post Natal development of Mandible Growth timing Sites of Growth Development of ramus,lingual tuberosity,condyle Growth by counterpart principle Ramus uprighting Age changes in Maxilla Age changes in mandible Developmental disturbances of face,lip,palate REFERENCES
ANATOMY OF THE MAXILLAPARTS OF MAXILLA. 1. BODY –large and pyramidal in shape. 2. FOUR PROCESSES. Frontal Zygomatic Alveolar Palatine Maxilla houses the largest sinus of the face, the maxillary sinus
DEVELOPMENT OF MAXILLAMaxilla forms within the maxillary prominences extending ventrally from the dorsal aspect of a much larger mandibular swelling.Ossification of maxilla begins slightly later than in the mandible.
DEVELOPMENT OF MAXILLA The primary ossification centre appears for each maxilla in the 7th week. The secondary centers are at- zygomatic, nasopalatine and orbitonasal areas It lies in the angle formed by the infraorbital nerve and anterior superior alveolar nerve,above the part of the dental lamina from which the canine tooth germ develops.
DEVELOPMENT OF MAXILLA The premaxilla begins to ossify from two centres in the latter part of the 7th week. Ossification spreads by:- Bony trough formed for infraorbital nerve- Palatine process Maxillary sinus – 16th week
Around the 4th week of intra-uterine life, thedeveloping brain and the pericardium form twoprominent bulges on the ventral aspect of theembryo. These bulges are separated by theprimitive oral cavity or stomatodeum. The floor of stomodeum is formed by thebuccopharyngeal membrane which separates itfrom the foregut.The pharyngeal arches are laid down on lateraland ventral aspects of the cranial most part ofthe foregut which lies in close approximationwith the stomodeum
Initially, there are 6 pharyngeal arches, but the 5th one usually disappears as soon as it is formed leaving only five. They are seperated by 4 branchial grooves. The first arch is called MANDIBULAR ARCH and second arch is called HYOID ARCH.
MECKEL’S CARTILAGE It is derived from the first branchial arch around the 41st – 45th day of intra-uterine life It extends from the cartilaginous otic capsule to the midline or symphysis and provides a template for guiding the growth of the mandible. A major portion of this cartilage disappears during growth and the remaining part develops into following
DEVELOPMENT OF PALATE Palatogenesis begins towards the end of 5th week and is completed by about 12th week. The palate develops from two primordia. Primary palate Secondary palate
PALATEPrimary palate At the end of 5th wk Develops from deep part of inter maxillary segment of the maxilla. Internal merging of medial nasal prominences. Represents only a small part of adult hard palate.
PALATESecondary palate Primordium of the hard and soft palate posterior to the incisive foramen. Begins to develop in the 6th wk, from shelf like structures called lateral palatine processes.
PALATE The tongue is initially interposed between the secondary palatal shelves. The palatal shelves become positioned above the tongue to allow for fusion in the midline.
PALATE The processes fuse in the midline and with the nasal septum and posterior part of primary palate. begins anteriorly during the 9th wk and is completed posteriorly by the 12th wk.
PALATE The posterior part of palatal processes remains unossified, they extend posteriorly beyond the nasal septum and fuse to form soft palate and uvula.
MECHANISM OF PALATE ELEVATION Elevation of the palateo Descent of tongue influenced by the growth of the Meckel’s cartilage and mandible.o Myoneural activity in the tongue.o Mouth opening reflexes
MECHANISMS OF PALATE ELEVATIONINTRINSIC Hydration and polymerization of intracellular substances producing an elastic elevating force. Differential growth of one side of the palatal shelf. Triger produced by a build up mucopolysaccharides. Serotonin release from neural tissue.
PALATEGenesis of cleft palateo Delay in shelf elevationo Disturbance in mechanism of shelf elevationo Failure of shelves to contact due to lack of growtho Failure to displace the tongue during closureo [Pierre robin syndrome]o Failure to fuse after contact as epithelium does not break downo Rupture after fusiono Defective merging
The formation of the palate involves the coordinated outgrowth, elevation and midline fusion of bilateral shelves leading to the separation of the oral and nasal cavities. Reciprocal signaling between adjacent fields of epithelial and mesenchymal cells directs palatal shelf growth and morphogenesis. Loss of function mutations in genes encoding FGF ligands and receptors have demonstrated a critical role for FGF signaling in mediating these epithelial–mesenchymal interactions. Hence, deletion that removes the FGF signaling antagonist Spry2 have cleft palate
PALATAL REMODELING External side of the anterior part of the maxillary arch is resorptive… with bone being added onto the inside of the arch…..increase in arch width…..increase in palatal width… V principle. Growth along mid palatal suture. As palate descends inferiorly…. - It occupies a different position
CLINICAL IMPLICATION In RME, remodeling of maxilla follows clinically induced displacement. lateral aspect of maxilla is resorptive. After fusion of mid palatal suture, increase in arch width is due to remodeling of the alveolar process.
INTER MAXILLARY SEGMENT It is composed of - a labial component : philtrum of upper lip -upper jaw component : carries four incisor teeth. - palatal component : that forms the triangular primary palate.The intermaxillary segment is continuous with the rostral portion of the nasal septum which is formed by the frontal prominence.
DEVELOPMENT OF MAXILLAGrowth occurs by: Apposition of bone Surface remodelingMovement downward & forwards: Cranial base growth Growth at sutures
POST NATAL GROWTH OF MAXILLA:- Growth of nasomaxillary complex is produced by following mechanism:- Displacement (translation ie acc’ to moss) :-leads to apposition of bone at sutures Surface remodeling(transposition) apposition resorption
DISPLACEMENT Primary displacement: the process of physical carry, takes place in conjunction with a bone’s own enlargement; joint contacts are important in this process. Secondary displacement: the movement of bone and its soft tissues is not directly related to its own enlargement .It is a fundamental part of the overall process of craniofacial enlargement
It is physical movement of bone. Causing secondary deposition of bone at sutures Downward and Forward growth
REMODELLING The functions of remodeling includes:a) To progressively create the changing size of each whole boneb) To sequentially relocate each of the component regions of the whole bone to allow for overall enlargement
As maxilla grows due to primary displacement its anterior surface tends to resorb as part of remodeling.
GROWTH AT SUTUREThe maxilla is connected to thecranium and the cranial base by anumber of sutures.These sutures include :Fronto- nasal suture.Fronto– maxillary suture.Zygomatico– maxillary suture.Pterygo– palatine suture.Zygomatico – temporal suture.
POSTNATAL GROWTH OF MAXILLA Growth in height - vertical Growth in width - transverse Growth in length - A -P
TRANSVERSE DIMENSION (IN WIDTH) Growth in midpalatine suture remodelling at lateral surface of alveolar process
VERTICAL DIMENSION (IN HEIGHT) Eruption of Primary Patatal teeth displacement remodelling
SECONDARY DISPLACEMENT OF NMC Expansion of Middle Cranial fossa has secondary displacement effect on anterior Cranial floor and thus on underlying NMC. Growth occurs in all the 3 dimensions A-P dimension(in length) Transverse dimension (in width) Transverse dimension (in width)
SECONDARY DISPLACEMENT(TRANSVERSE DIMENSION) Left and right temporal lobes move away from each other Increase in transverse width of middle cranial fossa Increase in width of maxilla by- Growth in mid palatine suture Remodeling at lateral aspect of alveolar process
SECONDARY DISPLACEMENT (A-P DIMENSION)Ant. & Middle cranial fossa move away from each otherNMC carried in forward directionBone deposited in tuberosity areaIncrease in A-P dimension
SECONDARY DISPLACEMENT(VERTICAL DIMENSION) Middle cranial base is in inclined plane Increase in dimension of Middle cranial basecauses displacement of NMC in downward direction
NASOMAXILLARY REMODELLING As clinically and biologically all inside and outside parts,region and surface participate directly in growth So key factors in NMC growth includes• Lacrimal suture• Maxillary Tuberosity• Vertical drift of teeth• Nasal airway• Palatal remodelling• Cheek bone & zygomatic arch• Orbital remodelling
LACRIMAL SUTURE(KEY GROWTH MEDIATOR) Diminutive flakes of bony islands surrounded by many sutures forms perilacrimal sutural system Without it a developmental ‘gridlock’ will occur among differentially developing multiple bones
It slides maxilla downward along its orbital contacts.This allows whole maxilla to get displaced inferiorly The lacrimal bone itself undergoes a remodeling rotation ,because the more medial superior part remains with the lesser expanding nasal bridge,while the more lateral inferior part moves markedly outward to keep pace with the greater expansion of the ethmoidal sinuses.
MAXILLARY TUBEROSITY The horizontal lengthening of the bony maxillary arch is produced by remodeling at the maxillary tuberosity Established by the posterior boundary of anterior cranial fossa It is a depository field the maxillary tuberosity is important in clinical orthodontics.it is also a major site of maxillary growth It lengthens posteriorly
MAXILLARY TUBEROSITY It lengthens posteriorly A-P Deposits on buccal surface width Deposits on alveolar ridge height
KEY RIDGE Reversal lines occur at Key Ridge Anterior to it : Resorption Posterior to it: Apposition* Reversal line: Irregular lines containing concavities directed away from the bundle bone and serving as histologic indications that resorption has taken place up to that line from the marrow side.
THE NASAL AIRWAY Lining surface of bony wall and floor Resorptive Lateral and anterior expansion of nasal chamber Downward relocation of palate The airway functions as a key stone for face Its obstruction can cause variation in facial skeleton
PALATAL REMODELING o Anteriorly - labial side is Resorptive oand palatal side is depository causes o widening of palate acc to V principle o As the palate grows inferiorly by the remodeling process, a nearly complete exchange of old for new hard and soft tissue occurs oGrowth at mid palatal suture plays a role in the progressive widening of the palate and alveolar arch
MAXILLARY SINUS All internal surfaces are resorptive except medial nasal wall Rapid continous downward growth Close proximity to buccal maxillary teeth
EXPANSION OF MAXILLARY SINUSAt birth - 7 mm length - 4 mm height - 4 mm widthExpands atrate of - 2 mm vertically yearly - 3mm A-P yearlyExpansion by - bone resorption - by tooth eruption (as vacated bone become pneumatized)
THE CHEEK BONE & ZYGOMATIC ARCH The growth changes of the malar complex are similar to those of maxilla itself The malar region and the anterior part of the zygoma undergo posterior remodeling movements. The inferior edge of the zygoma is heavily depository As the malar region grows and becomes relocated posteriorly, the nasal region is enlarging in an opposite,anterior direction,drawing out the nose and making face deeper,anteroposteriorly
ORBITAL GROWTH Follows ‘V’ principle Enlarging displacement occurs Growth at sutures orbital floor moves
VARIATION IN NMC GROWTH class II ( excessive mid face growth) class III (decreased midface growth) It’s common site for single most common craniofacial anamoly Cleft Palate
DEVELOPMENT OF MANDIBLE 2nd bone to ossify Intramembranous + endochondrial 6th week of intrauterine life
36-38th day mandibular ectomesenchyme interacts with mandibular epithelium before primary ossification. Intramembranous bone lies lateral to cartilage. First ossification centre for each half arises in 6th week in region of bifurcation of IAN into mental, the ossification spreads dorsally and ventrally to form ramus and body. Ossification stops at site where it would be lingula. Medially it meets its fellow counter part,distally upto middle ear. Major cartilage disappears.
Secondary accessory cartilages occur bet 10-14th weeks to form head of condyle, coronoid,mental protuberence Coronoid cartilage: fuses with expanding intramembranous ramus before birth Mental:1-2 small cartilages appear and ossify in 7th month iu in fibrous symphysial tissue Condylar cartilage: appear 10th wk. this is promordium for future condyle. cartilage differentiate by interstitial n appositional growth.
By 14th wk, 1st evidence of endochondral bone formtation Condyle cart is an imp growth centre for ramus. Condylar growth ia at its peak at puberty. Occurs12-14 months post natally,2halves fuse into synostosis
Mandible appears as single bone. Basal bone forms one unit to with alveolar, condylar, coroniod, angular process and chin is attached. They grow by functional matrix theory Teeth act as functional matrix for development of alveolar bone Temporalis influences coroniod process Masseter n med pterygoid – at angle Lateral pterygoid – at condyle
POST NATAL GROWTH ANDDEVELOPMENTGROWTH TIMINGGrowth of width of mandible is completed first, then growth in length and finally growth in height
POST NATAL GROWTH ANDDEVELOPMENT WIDTH OF MANDIBLE Growth in width is completed before adolescent growth spurt Intercanine width does increase after 12 years Both molar and bicondylar width shows small increase until growth in length ends
POST NATAL GROWTH ANDDEVELOPMENT GROWTH IN LENGTH Growth in length continues through puberty Girls—14-15 years boys---18-19 years
MAIN SITES OF POST NATAL GROWTHIN THE MANDIBLE Condylar cartilage Posterior border of the Rami Alveolar ridges
CONDYLAR CARTILAGE Secondary cartilage Dual in function a) Articular b)Growth Not a primary centre for growth ,but Secondary in evolution Secondary in embryonic origin Secondary in adaptive responses to changing developments
DEVELOPMENT OF MANDIBLE• Ramus• Lingual tuberosity• Condyle
Ramus• It provides an attachment base for masticatory muscles.• It positions the lower arch in occlusion with the upper.• It is continuously adaptive to the multitude of changing craniofacial conditions.
Superior part of ramus below sigmoid notch Lingual : deposition Buccal : Resorption Lower part of ramus below the Coronoid process Buccal : depostion Lingual : Resorption
• The mandible as a whole displaces anteriorly and inferiorly.
• The former anterior part of the ramus becomes the corpus by resorptive and depository remodeling.
THE LINGUAL TUBEROSITY Major site of mandibular growth and remodeling. Direct anatomic equivalent of the maxillary tuberosity. Effective boundary between the basic structures- ramus and corpus.
Grows posteriorly by deposits on the on its posterior surface Its prominence is augmented by the presence of a resorptive field below it, lingual fossa. Simultaneuosly the part of the ramus behind the tuberosity remodels medially
RAMUS TO CORPUS CONVERSION The anterior border of the ramus resorbs relocating the ramus in a posterior direction. Development takes place according to the ‘V’ principle.
Coronoid process- its lingual surface faces posteriorly superiorly medially all at once. Deposits of bone on the lingual surface bring about growth superiorly, posteriorly and medially.
• The buccal surface of the coronoid process undergoes resorption.• The area of the ramus below the sigmoid notch and superior portion of the condylar neck…deposition on lingual and resorption on buccal side.• Inferior edge of the mandible at the Corpus-Ramus junction……..resorption…….antegonial notch.
Theclinical presence of a deep mandibular antegonial notch is indicative of a diminished mandibular growth potential and a vertically directed mandibular growth pattern. Singer CP,Mamandras AH,Hunter WS Gonial region is anatomically variable. The buccal side can be resorptive or depository depending on the direction of gonial flares.
• Mental foramen is near the lower border at birth.• Adult: midway• Elderly: near the upper border.
THE CONDYLE• Major site of growth with considerable clinical significance.• Endochondral growth occurs only at the articular contact part of the condyle.• Cartilage is non vascular, hydrophilic and pressure tolerant.• This mechanism develops as a response to local demands.
CONDYLE Lack of mandibular condyle and variable amounts of ramus…. Lack action of lateral pterygoid muscle on the same side. Deviation of mandible on oral opening. The condylar neck consists of intramembranous bone. The lingual and buccal sides of the neck have resorptive surfaces. What used to be the condyle becomes the neck by periosteal resorption and endosteal deposition..….. ‘V’ principle.
Where does the physical force that causesprimary displacement of the mandible come from….??• Condylar remodeling acts with displacement as a co participant but not as the driving force in response to common activating signals.• As the mandible is displaced away from its basicranial articular contact, the condyle and the ramus secondarily remodel towards it.
RAMUS UPRIGHTING• The ramus normally becomes vertically aligned during its development.• A remodeling rotation of the ramus alignment occurs.
CLINICAL IMPLICATION• It must lengthen vertically• - to keep in pace with the growth of the pharynx and middle cranial fossa. - to accommodate the vertical nasomaxillary growth.• Gonial angle• The vertical growth continues even after horizontal has ceased to match the continued vertical growth of the midface.
• Condylar growth now becomes more vertically directed.• The direction of resorption and deposition of the ramus reverses.
• Periosteal resorption on the labial bony cortex , deposition on the alveolar surface of the labial cortex, resorption on the alveolar surface of the lingual cortex, deposition on the lingual side of the lingual cortex.
AGE CHANGES IN MAXILLAAT BIRTH: The transverse and anteroposterior diameters are more than the vertical diameter. Frontal process is well marked Inferior surface of maxilla at birth Body consists of a little more than the alveolar process The tooth sockets reaching to the floor of orbit Maxillary sinus is a mere furrow on the lateral wall of the nose. Anterior surface of maxilla at birth
IN ADULT: Vertical diameter is greatest due to the development of the alveolar process and increase in the size of the sinus.IN THE OLD: The bone reverts to infantile condition. Its height is a result of absorption of the alveolar process.
AGE CHANGES IN MANDIBLEIn Infants & Children: The two halves of mandible fuse during the first year of life. At birth, the mental foramen,opens below the sockets for the two decidious molar teeth near the lower border. This is because the bone is made up of only the alveolar part with teeth sockets. The mandibular canal runs near the lower border. The foramen and canal gradually shift upwards. Lower jaw of child and adult, showing the mental foramen.
IN ADULTS The mental foramen opens midway between the upper and lower borders because the alveolar and subalveloar parts of the bone equally developed. The mandibular canal runs parallel with the mylohyoid line. The angle reduces to about 110 or 120 degrees because the ramus becomes almost vertical
IN OLD AGE Teeth fall out and alveolar border is absorbed, so that the height of the body is markedly reduced. The mental foramen and the mandibular canal are close to the alveolar bone. The angle again becomes obtuse about 140 degrees because the ramus is oblique.
DEVELOPMENTAL DISTURBANCES OFPALATE1) Cleft palateDuring the 7th week, a shift in the blood supply of the face from the internal carotid to the external carotid artery occurs as a result of stapedial artery atrophy.This is a critical time for mid face developmentDeficient blood supply defects of upper lip and palate.2) Median cleft face syndrome
The depth of the mandibular antegonial notch as anindicator of mandibular growth potentialAm J Orthod Dentofacial Orthop. 1987 Feb;91(2):117-24.Singer CP, Mamandras AH, Hunter WS.A dosage-dependent role for Spry2 in growth andpatterningduring palate development Ian C. Welsh, Aaron Hagge-Greenberg, Timothy P.O’Brien* Mechanisms of Development 124 (2007) 746–761
DERIVATIVES OF PHARYNGEAL ARCHESARCHES NERVE MUSCLES SKELETAL ARTERYI Maxillary arch Trigeminal MOM Mandible, Maxilary Maxilla,incus, malleusII Hyoid Facial Muscles of facial Stapes, styloid Stapedial(embr expression process,lesser yonic) cornu & upper Corticotympani part of body of c(adult) hyoid,III Glossopharyng Stylopharyngeu Gr. Cornu & Common eal s lower part of carotid body of hyoidIV & VI Sup laryngeal & Intrinsic Thyroid, IV- rt subclavian recurrent muscles of cricoid, laryngeal larynx, pharynx, arytenoid, VI - pulmonary levetor palatini corniculate, cuneform
AGE CHANGES IN MANDIBLE• Mandible is relatively small at birth.• Eruption of teeth and development of alveolar process contribute to its vertical growth.• Assumes a more forward position.• With the loss of teeth, alveolar process resorbs reducing the mandibular height.