Key to Past 25 years TN MGR Med Univ Questions - Development of Face Chapter

Development of face

Meckel’s cartilage: 

Place where it is found; cartilage of which arch; the week at which it is formed – from which structure – forms which structures – at which week - how it acts as a scaffold for the mandible and the persistence of the cartilage in adult as the inner ear bones- how mandible develops from this including the type of ossification

Development of Maxilla & Mandible:

Maxilla: head development – begins/ends at which week – mesenchymal prominence - development of medial and nasal process- descent and movement of the process – concept of premaxilla, primary palate, secondary palate – descent of tongue – fusion of processes – mechanism involved – clinical significance of non-fusion – clefts of maxilla – Diagrams Mandible: week of initiation in IUL – Meckel’s cartilage formation - Place where it is found; cartilage of which arch; the week at which it is formed – from which structure – forms which structures – at which week - how it acts as a scaffold for the mandible and the persistence of the cartilage in adult as the inner ear bones- how mandible develops from this including the type of ossification – Growth of mandible – development of lingual, nerve innervation's and blood supply

Development of mandible: 

Week of initiation in IUL – Meckel’s cartilage formation - Place where it is found; cartilage of which arch; the week at which it is formed – from which structure – forms which structures – at which week - how it acts as a scaffold for the mandible and the persistence of the cartilage in adult as the inner ear bones- how mandible develops from this including the type of ossification – Growth of mandible – development of lingual, nerve innervation's and blood supply - Diagrams

Development of middle third of face: 

4^th week IUL - facial prominence's – 1^st pharyngeal arches appear - Maxillary prominence - mandibular prominence - frontonasal prominence - nasal (olfactory) placodes - nasal pits - nasal prominence – lateral - medial - nasolacrimal groove  - nasolacrimal duct- lacrimal sac – formation of cheeks and maxilla. Nose- 5 facial prominence's - the frontal - medial nasal prominence - lateral nasal prominence. Skin development – innervation's – Reichert Cartilage - Diagrams

Derivatives of second pharyngeal arch: 

Hyoid arch- Reichert’s cartilage- stapes, styloid process of the temporal bone, stylohyoid ligament, and ventrally, the lesser horn and upper part of the body of the hyoid bone.  Muscles of the hyoid arch - stapedius, stylohyoid, posterior belly of the digastric, auricular, and muscles of facial expression. The facial nerve, the nerve of the second arch, supplies all of these muscles. Diagrams

Development of tongue: 

4 weeks in the form of two lateral lingual swellings and one medial swelling, the tuberculum impar - first pharyngeal arch - copula, or hypobranchial eminence - a third median swelling, formed by the posterior part of the fourth arch - laryngeal orifice – relationship with arytenoid swellings  - lateral lingual swellings - increase in size – tuberculum impar and merge - body of the tongue. Tongue mucosa - from the first pharyngeal arch - sensory innervation's - terminal sulcus. Root of tongue and the 2^nd, 3^rd and 4^th pharyngeal arch.  tongue muscles - myoblasts  - occipital somites - hypoglossal nerve. Sensory, motor and taste supply to tongue. Two diagrams. 

(A Special Thanks to Colleagues at Ragas Dental College & Hospital, Chennai)

Tooth Morphology

In the maxillary arch the lingual alveoli is the thinnest in the	Molars
The arterial supply to the jaws is through the	Internal maxillary artery
The anterior and middle superior alveolar arteries are branches of	Infra orbital artery. The posterior superior alveolar artery is a branch of internal maxillary artery.
The strongest portion of the capsular ligament is the	Tempromandibular ligament
Muscle contraction is monitored by receptors in muscles by	Muscle spindles
The centric occlusion is a	Tooth determined position
The normal inter-occlusal space is about	1-3 millimeter
Voluntary mandibular retrusion with mouth closed is mediated by	Posterior fibers of temporalis
The number of pulp horn in permanent maxillary canine in its buccal aspect is	One
The number of pulp horn in permanent maxillary lateral incisor in its buccal aspect is	Two

Tooth Morphology

The apex of the mesiobuccal root is on a line with the tip of the mesiobuccal cusp in the permanent	Maxillary first molar. The apex of the mesiobuccal root is on a line with the buccal groove in the permanent maxillary second molar.
The apex of the palatal root is in line with distolingual cusp in the	Maxillary second molar. The apex of the palatal root is in line with lingual groove in the first molar.
Crowns of permanent mandibular molars are	Wider mesiodistally than buccolingually. For maxillary molars, premolars and mandibular premolars, the crowns are wider buccolingually than mesiodistally.
The number of cusps in a typical human permanent first mandibular molar have	2 Buccal, 2 lingual, 1 distal cusps
During the root formation the apical foramen is actually__________ than pulp chamber at it initial stage of formation.	Larger
If accessory foramina at the cervical third of root leads to main root canal it is a	Lateral canal
The largest pulp chamber in human permanent dentition belongs to the	Maxillary canine
The pulp chamber floor is below the cervical line in the	Permanent maxillary first premolar
The cross section of crown at the cervical level is kidney shaped in	Permanent maxillary first premolar
The major portion of maxillary canine fossa is above the roots of	Premolars

Oral Histology

Questions	Answer
Matrix formation in cementum is faster in	Cellular cementum, owing to presence of cementoblast and cementocytes
The cementocytic process interconnect with each other through	gap junctions
incremental lines of Salter are rich in	Osteopontin
The first formed cementum is	Acellular extrinsic fibre cementum
The type of cementum that has no role in attachment is	Intrinsic fibre cementum
What is cellular mixed stratified cementum	In the apical region and the furcations, acellular extrinsic and cellular intrinsic fibre type of cementum presents in alternating layers, which is called cellular mixed stratified cementum
The varied origin of mixed cementum can be best demonstrated by	Polarized light, that show the different orientation in different shades
The proteins absent in acellular extrinsic fibre cementum are	Dentin sialoprotein, fibronectin and tenascin. And deficient in lumican, versican, decorin, biglycan and fibromodulin
In the cervical region of tooth, loss of reduced enamel epithelium leads to	Formation of afibrillar cementum
The number of fibers in acellular extrinsic fibres is	30,000 per sq mm

Oral Histology

Questions	Answer
The stage in which a dental follicle is innervated is	cap stage of tooth development
The primary glycosaminoglycan in cementum is	Chondroitin sulphate
The marker to differentiate bone and cementum is	Cementum-derived attached protein
In adult teeth, uncalcified cementum is in association with	cellular cementum. Thin layer of 3 to 5 micrometer. Called as Precementum
In cementum, sialoproteins are located along the	cementum matrix
In cementum, osteopontin are located along the	incremental lines
Cementum derived attached protein are found in the	cementum matrix
The chondroitin sulphate in cementum is found along the	lacunae of cementum
The type of cementum in interradicular areas is	cellular cementum.
Primary cementum is the	acellular cementum. Secondary is cellular cementum

OralHistology

Questions	Answer
Calcitonin -gene-related peptide and substance P in pulp cause	Vasodilation and increased capillary permeability
The approximate number of axons entering the apical foramen is	2500 axons
The percentage of axons in tooth that are myelinated is	25 percentage
The type of nerve fibres in teeth	90% are narrow A delta  and 10% are wider A beta group []
The Plexus of Raschkow is not evident till	The tooth is erupted
The unsheathed axons of dentin are most often restricted to	Coronal dentin
What is predentinal plexus of Bradlaw	Is an area where a number of axons congregate and houses unsheathed axons. Also houses the dentinal dentritic antigen presenting cell
Subodontoblastic zone contains a lot of	Cell processes. It is anuclear and devoid of other structures as per EM studies
In pulp, the level of glycosaminoglycan peaks till	Eruption of teeth
The main ground substance in developing pulp  is the	Chondroitin sulfate. In mature pulp it is hyaluronan

Tooth Morphology

Questions	Answer
Function of biglycan	Help to regulate collagen fbrillogenesis
Function of tenascin	Associated with cell movements
Function of osteoadherin	Associated with mineralization
Glycoproteins in pulp	Collagen, fibronectin and tenascin
Why is odontoblast layer described as pseudostratified	The nuclei of adjacent odontoblast lie at different levels and sectioning plane cause this appearance
Cell junction present in odontoblasts are	Macula adherens, tight junctions and gap junction
The control of blood flow is under	Nervous system
The pulpal arteriolar smooth muscle is innervated by	Sympathetic nerves
The vasoconstrictor tone of pulpal arterioles are mainatined by	Sympathetic nerves and neurotransmitters are noradrnealine and neuropeptide Y
The most prominent neuropeptide in pulpal nerves are	Calcitonin -gene-related peptide and substance P