The adult ear has three parts:

External ear Middle ear Inner/ internal

Development of Sense Organs / Establishment of Structures in the Head and Neck Region Flashcards by Belle Unknown

*ESTABLISHMENT OF THE EYE

Median area near the rostral margin of the future prosencephalon (neural tube) at the level of the diencephalon is called the ____

optic field

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*ESTABLISHMENT OF THE EYE

Interaction of this area to the underlying mesoderm of the head causes the single optic field to separate into two lateral eye forming regions

Failure to separate completely results to a condition called ____, single eye formed at the center of the head

cyclopia

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*ESTABLISHMENT OF THE EYE

When the rostral end of the neural tube closed, the prosencephalon expands laterally, the optic field divide to form the ____ which retains its attachment to the
prosencephalon of thru the ____

optic vesicles

optic stalk

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*ESTABLISHMENT OF THE EYE

Lens placode which subsequently invaginate to form the ____ then break away from the surface ectoderm

lens vesicles

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*ESTABLISHMENT OF THE EYE

While the lens vesicle is being formed, optic vesicle invaginate to form a double layered ____

optic cup

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*ESTABLISHMENT OF THE EYE

Outer layer forms the ____ while the inner layer becomes the ____ which is the light receptor area

pigmented retina

nervous retina

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failure of the optic vesicle to form or interference with the normal growth of the optic cup; often result from deficiency of vitamin A in dogs, pigs, and cows; hereditary or acquired.

Anopthalmia/ micropthalmia-

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medial/ lateral deviation of of the eyeball

Medial/ Lateral strabismus-

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defect in the growth of the optic cup which is usually seen in the retina and choroid as a focal dysplasia

Collie eye-

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loss in the clarity of the lens which maybe hereditary in dogs; appear occasionally in cattle, rarely in horses and cats

Cataract-

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The adult ear has three parts:

External ear
Middle ear
Inner/ internal

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composed of the pinna, external auditory meatus and outer layer of the tympanic membrane- sound waves collection

External ear

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composed of the ear ossicles and inner layer of the tympanic membrane used for the conduction of sound waves

Middle ear

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composed of the bony and membranous labyrinth which function for equilibrium

Inner/ internal ear

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*ESTABLISHMENT OF THE EAR

Of all the three parts of the ear, the ____ is the first to develop
At the level of the myelencephalon ectoderm, a localized thickening on either side appear called the ____

internal ear

otic placode

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*ESTABLISHMENT OF THE EAR

Which then invaginate in the underlying mesoderm as otic pit then become _____

otic vesicle

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Develops after the formation and growth of the cochlear duct
The inner and outer hair cells then differentiate into their appropriate positions and are followed by the organization of the supporting cells
It is located in between the scala tynpani and the scala media

ORGAN OF CORTI

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*Organ of Corti

At ____, the utricle forms a flattened outpocketings
The central portions appose and then disappear and forms the ____
One end widens and become the ampulla
During the formation of the otic vesicle, a small group of cells breaks away from its wall and forms the _____
Also reinvested cells from the neural crest

6th wk

semicircular canals

statoacoustic ganglion

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Components of Otic Vesicle (Otocyst)

Ventral saccular portion (small constricted part)
Dorsal utricular portion (small constricted part)

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Components of which Otic Vesicle

Saccule
Cochlear duct (organ of Corti)
Spiral ganglion of the vestibulo-cochlear nerve

Ventral saccular portion

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Components of which Otic Vesicle

Utricle
Semicircular canal/ duct
Endolymphatic duct
Vestibular ganglion of the vestibulo cochlear nerve

Dorsal utricular portion

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DEVELOPMENT OF THE MIDDLE EAR:
* Composed of:

Eardrum/ tympanic membrane
Tympanic cavity
Malleus or hammer
Incus or anvil
Stapes (or stirrup)-

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cone shaped membrane that separates the external ear from the middle ear

Eardrum/ tympanic membrane-

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contains the 3 small bones

Tympanic cavity-

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long handle attached to the eardrum

Malleus or hammer-

the bridge bone between the malleus

Incus or anvil-

the footplate; the smallest bone in the body

Stapes (or stirrup)-

*DEVELOPMENT OF THE MIDDLE EAR: * At the ____, tubulotympanic sulcus develops as extension of the endodermal epithelium of the 1st pharyngeal pouch * Distal part is the ____ * Proximal part is the ____

4th wk primitive tympanic cavity auditory tube/ eustachian tube

*The Ossicles PRIMORDIAL STRUCTURES: ____ derived from pharyngeal pouch 1 will give rise to the head of malleus and body of incus

Meckel’s cartilage

*The Ossicles PRIMORDIAL STRUCTURES: ____ derived from the pharyngeal arch 2 will give rise to the manubrium of malleus, long process of incus and supstructure of stapes

Reichert cartilage

*The Ossicles PRIMORDIAL STRUCTURES: Development of the stapes is induced by a depression on the otic capsule, the ____

lamina stapedialis

THE EXTERNAL EAR COMPOSED OF:

* External auditory meatus * Tympanic membrane * Auricle/ pinna-

developed from mesenchymal proliferations at the dorsal ends of pharyngeal arches 1 and 2 surrounding the pharyngeal cleft 1

Auricle/ pinna-

The pinna of the ear turns forward on later and covers the ____. The auditory canal is completely closed by day ___. The external ear remains plugged with periderm for the first ___ days after birth.

auditory canal 18 16

Growth of mesenchymal tissue (connective tissue) in the cranial region of the embryo results in the formation of arches, separated by clefts. These are the ____ and ____ that form in the neck region of the developing embryo

pharyngeal arches pharyngeal clefts

*PHARYNGEAL POUCHES, ARCHES, AND CLEFTS Simultaneously, outpocketings appear on the lateral wall, the ____

pharyngeal pouches

* ____ separate the pharyngeal arches on the inner (endodermal) surface * There are ____ pairs of pouches, but only ____ give rise to structures in the adult

Pharyngeal pouches five four

*PHARYNGEAL POUCHES, ARCHES, AND CLEFTS Initially, there are 4 pharyngeal clefts. However, only the first cleft gives rise to a permanent structure in the adult- the ____

external auditory meatus

*PHARYNGEAL POUCHES, ARCHES, AND CLEFTS The 2nd, 3rd,and 4th clefts only form temporary cervical sinuses- which are then obliterated by the rapidly proliferating ____

2nd pharyngeal arch

* The six pharyngeal arches- however, the ___ regresses soon after forming.

5th

*PHARYNGEAL POUCHES, ARCHES, AND CLEFTS * Each arch has a muscular component, a skeletal and cartilaginous supporting element as well as a vascular component and is innervated by an arch-associated ____ * In the adult, each pharyngeal arch is associated with specific structures within the head and neck

cranial nerve

*Development of the Face * ____- the face begins to take shape * There are three regions of the face: orbital, nasal, oral * Oral region is marked by the ____ * ____ (primordium) develop bilaterally at the inferolateral corners of the frontonasal process

5th wk stomodeum Nasal placode

*Development of the Face * Nasal placode invaginates to form the ____ * Development of nasal placodes in ____ manner lead to the formation of medial and lateral nasal process * ____ in the forebrain signals the normal descent of the fronto nasal prominence

nasal pit horse shoe S-H-H (sonic hedgehog gene)

*Development of the Face * At ___ and ___- nasal and maxillary processes expand and fuse to form the upper lip and cheeks

6th and 7th wk

*Development of the Face when the mandibular swellings become continuous with the mandibular depression filled with the mesenchyme forms the ____

upper lip

*Development of the Face Mandibular process forms the ____

angle of the mouth

*Development of the Face _____ forms between the lateral nasal process and maxillary process

Nasolacrimal groove and duct

*Development of the Face This group of cells are called ____ that will form the the forehead and nasal regions of the face

frontonasal mesenchyme

*Adult parts of the nose and their derivatives Fused L&R medial nasal swellings

Nasal septum

*Adult parts of the nose and their derivatives Lateral nasal swellings

Alae of the nose

*Adult parts of the nose and their derivatives External opening of olfactory pits

External nares/ nostrils

*Adult parts of the nose and their derivatives Caudal openings of olfactory pits into oral cavity

Posterior nares

*Adult parts of the nose and their derivatives Nasolacrimal groove

Nasolacrimal duct

*Adult parts of the nose and their derivatives Frontal prominence

Bridge of nose

*Adult parts of the nose and their derivatives Olfactory pit

Nasal cavity

*Formation of the Tongue 4th wk at pharyngeal arches (PA) ____- tongue begins to form

1,2,3, 4

Palate develops from the 2 primordia:

primary and secondary

* Primary palate arising from the medial nasal process forms a “____” composed of mesoderm * Eventually extend to form the floor of the cavity

wedge shaped mass

* Secondary palate develops from 2 lateral palatine processes * As the mandible develops, tongue drops and the ____ grow medially and fused in the midline * Also fuse with the nasal septum and primary palate

palatine processes

* Ossification occurs in anteroposterior direction * Posterior portions of the lateral palatine processes do not become ossified but extend past the nasal septum and fuse to form the ____ and ___

soft palate and uvula

*Development of the Lips and Gums * Midway between the medial and lateral (rostral) margin of the oral cavity thickens to form the ____ * Extends in the form of an arch along the inner margins of the mandibular and maxillary processes * Lamina thickens and forms a solid cord of epithelial cells which invade the underlying mesenchyme

labiogingival lamina

*Development of the Lips and Gums A groove forms in the lamina called ____; tissue rostral and lateral to the groove forms the ____ and the tissue caudal and medial to the groove forms the ____

labiogingival groove/sulcus lips gums

*Development of the Tooth Stomodeal ectoderm medial to the ____ forms a focal thickening called ____ (evident in canine at 25 days)

labiogingival lamina dental ledge/ lamina

*Development of the Tooth Invaginates and forms the ____

dental bud

*Development of the Tooth Expand and branches to form the _____- a cup shaped structure characteristic of the crown of the tooth

enamel organ

*Development of the Tooth Mesenchymal tissue (from neural crest) inside the cup-shaped enamel organ is called ____

dental papilla

*Development of the Tooth * Enamel organ and dental lamina forms the ____ * Between the enamel organ and surface of the oral cavity, a tissue bud off that forms the ____

deciduous or milk tooth permanent tooth

*Development of the Matrix Component of the Tooth * Epithelial cells near the deeper layer of the enamel organ become the ____- cementum formers * Inner layer of the enamel organ differentiates into ____- enamel forming cells * Mesenchymal cells next to the ameloblasts differentitate into _____- dentine formers

cementoblasts ameloblasts odontoblasts

the sensitive part of the tooth

dental pulp-

____ is the primary matrix component of the tooth, surrounds the dental pulp-

Dentine

*Development of the Tooth ____ draw their raw materials from the blood vessels in the dental pulp and secrete their products towards the enamel organ

Odontoblasts

*Development of the Tooth Like the odontoblast, the ameloblasts pushed back as they secrete the ____ towards the dentine and upon eruption of the tooth, the ____

enamel ameloblast degenerate

Formation of the dentine and enamel start at the _____ towards the root of the tooth

tip of the crown

*Development of the Tooth When the tooth acquire its full growth and definitive position in the alveolus of the jaw, the _____ begin to secrete the cementum the same way in the formation of the bone

cementoblasts

*Development of the Tooth ______ (fibrous CT) located in periodontal membrane attached tooth to the bones of the jaw

Sharpey’s fibers

part of the tooth visible, composed of dentine and enamel

Crown

the part embedded in the alveolus made of the dentine, enamel, and cementum

Root-

region between the crown and root of the tooth

Neck

tissue inside the root containing blood vessels and nerves, thus is the most sensitive part of the tooth

Dental Pulp

bone has __% dentine, __% enamel and _% organic substrate

45% dentine 30% enamel 5% organic substrate

Microscopic structure, bone, dentine and enamel are dissimilar as bone are formed in ____ and has cells scattered through it while the dentine and enamel are not and there are no cells scattered in their matrix as the cells back away after they secrete their finished products.

lamellation