Development of Sense Organs / Establishment of Structures in the Head and Neck Region Flashcards
*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
*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
*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
*ESTABLISHMENT OF THE EYE
Lens placode which subsequently invaginate to form the ____ then break away from the surface ectoderm
lens vesicles
*ESTABLISHMENT OF THE EYE
While the lens vesicle is being formed, optic vesicle invaginate to form a double layered ____
optic cup
*ESTABLISHMENT OF THE EYE
Outer layer forms the ____ while the inner layer becomes the ____ which is the light receptor area
pigmented retina
nervous retina
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-
medial/ lateral deviation of of the eyeball
Medial/ Lateral strabismus-
defect in the growth of the optic cup which is usually seen in the retina and choroid as a focal dysplasia
Collie eye-
loss in the clarity of the lens which maybe hereditary in dogs; appear occasionally in cattle, rarely in horses and cats
Cataract-
- The adult ear has three parts:
- External ear
- Middle ear
- Inner/ internal
composed of the pinna, external auditory meatus and outer layer of the tympanic membrane- sound waves collection
External ear
composed of the ear ossicles and inner layer of the tympanic membrane used for the conduction of sound waves
Middle ear
composed of the bony and membranous labyrinth which function for equilibrium
Inner/ internal ear
*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
*ESTABLISHMENT OF THE EAR
- Which then invaginate in the underlying mesoderm as otic pit then become _____
otic vesicle
- 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
*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
Components of Otic Vesicle (Otocyst)
- Ventral saccular portion (small constricted part)
- Dorsal utricular portion (small constricted part)
Components of which Otic Vesicle
- Saccule
- Cochlear duct (organ of Corti)
- Spiral ganglion of the vestibulo-cochlear nerve
Ventral saccular portion
Components of which Otic Vesicle
- Utricle
- Semicircular canal/ duct
- Endolymphatic duct
- Vestibular ganglion of the vestibulo cochlear nerve
Dorsal utricular portion
DEVELOPMENT OF THE MIDDLE EAR:
* Composed of:
- Eardrum/ tympanic membrane
- Tympanic cavity
- Malleus or hammer
- Incus or anvil
- Stapes (or stirrup)-
cone shaped membrane that separates the external ear from the middle ear
Eardrum/ tympanic membrane-
contains the 3 small bones
Tympanic cavity-
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
