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LECOM MS1 Gross Anatomy - Head/Neck 2022 (+Shelf) > Ear & Eye Development > Flashcards

Ear & Eye Development Flashcards

1
Q

When does the ear begin to develop?

A

4th week

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2
Q

What will the otic vesicle give rise to?

A

Utricle – forms the endolymphatic duct, utricle and semicircular canals
Saccule – forms the saccule and cochlear duct

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3
Q

What are the specialized hair cells in the ear?

A
  1. Cristae ampullaris – in the ampulla of each semicircular canal
  2. Macula – one in the utricle and one in the saccule
  3. Cochlear – numerous along the cochlear duct
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4
Q

Spiral ganglion is related to…

A

Cochlear duct, involved in hearing

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5
Q

Vestibular ganglion is related to…

A

Remaining hair cells, involved in detection of head movement

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6
Q

What does the otic vesicle signal?

A

Surrounding mesenchyme to condense and form an otic capsule

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7
Q

What will the otic capsule contribute to?

A

Petrous part of temporal bone

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8
Q

Rubella infection can cause…

A

Malformation of cochlea and deafness

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9
Q

What pharyngeal apparatus will contribute to the tympanic membrane?

A

First pharyngeal groove and pouch

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10
Q

What is the pharyngeal groove lined by? The pouch?

A

Groove -> endoderm
Pouch -> ectoderm + mesenchyme (mesoderm)

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11
Q

The tympanic membrane is comprised of…

A

All three germ layers!

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12
Q

Tubotymapnic recess is continuous with…

A

Mastoid antrum + nasopharynx via pharyngotympanic tube

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13
Q

Tensor tympani embryology

A

attached to the malleus; it derives from the mesenchyme of the first arch and is innervated by the nerve of the first arch (CN V)

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14
Q

Stapedius embryology

A

attached to the stapes; it derives from the cartilage of the second arch and is innervated by the facial nerve

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15
Q

What is the external ear innervated by?

A

CN V + VII

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16
Q

Anotia

A

Absence of ear

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17
Q

Microtia

A

Small ear

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18
Q

Auricular appendages

A

Persistence of extra auricular hillocks, absence of auricle

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19
Q

Preauricular sinuses

A

Small depressions located anterior to the auricle. This defect results from abnormal closure of the first pharyngeal groove. These sinuses have only cosmetic significance but they can become infected

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20
Q

If cells situated in front of the tympanic membrane fail to die…

A

Atresia of the external auditory meatus

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21
Q

Atresia of the external auditory meatus

A

Blockage of the external canal

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22
Q

Congenital cholesteatoma

A

Epidermoid tissue within the tympanic membrane

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23
Q

The eye develops from four sources

A
  1. neuroectoderm – retina, posterior layers of the iris and optic nerve
  2. surface ectoderm – lens and corneal epithelium
  3. mesoderm – fibrous and vascular coats
  4. neural crest – choroid, sclera and corneal endothelium
24
Q

When does the eye begin to develop?

A

4th week

25
Q

What will the lens placode become?

A

Form lens pits and will invaginate to form a lens vesicle

26
Q

What will the optic stalk become?

A

Optic nerve

27
Q

What will the hyaloid artery become?

A

Central artery of retina

28
Q

Where will the retina develop?

A

The walls of the optic cup
The outer layer becomes the pigmented retina; the inner layer becomes the neural retina

29
Q

What do the ganglion cells mostly form?

A

Superficial portion of neural retina

30
Q

The neural retina and the pigmented retina are separated by…

A

Intraretinal space

31
Q

Where does the ciliary body derive from?

A

Choroid mesenchyme, along with both layers of the optic cup

32
Q

What are the ciliary muscles derived from?

A

Choroid mesenchyme from the anterior edge of the optic cup

33
Q

Where is the iris formed?

A

Front edge of optic cup

34
Q

The lens are derived from…

A

Surface ectoderm that invaginated

35
Q

The hyaloid artery supplies…

A

Developing lens

36
Q

When the hyaloid artery obliterates, the lens becomes…

A

Avascular

37
Q

Cornea is formed from…

A
  1. Surface ectoderm – corneal epithelium
  2. Mesoderm – connective tissue
  3. Neural crest – corneal endothelium
38
Q

Choroid contributes to the formation of…

A

The ciliary body

39
Q

When do the eyelids seperate?

A

During the 5th to 7th months of development

40
Q

How do the aqueous chambers form?

A

Anterior chamber -> between lens & cornea
Posterior chamber -> space in mesenchyme posterior to iris and anterior to the lens
Vitreous body forms in cavity of optic cup

41
Q

Where are the extrinsic eye muscles formed from?

A

Prechordal plate mesoderm (preotic somites)

42
Q

What is the sequence of extrinsic eye muscles?

A
  1. lateral and superior rectus
    -> the levator palpebrae forms from a splitting of the superior rectus
  2. superior oblique
  3. medial rectus, inferior rectus and inferior oblique
    -> the inferior rectus and inferior oblique form from a common precursor
43
Q

When does the oculomotor nerve reach the orbit?

A

early in 5th week

44
Q

When does the abducens & trochlear nerve reach the orbit?

A

end of 5th week

45
Q

Congenital retinal detachment

A

Recall that the two layers of the retina were separated by an intraretinal space. Normally, there is some degree of fusion between these two layers. If these layers
fail to fuse during development the defect is congenital. Retinal detachment can occur following a blow to the eye in which case fluid can accumulate and vision can be impaired

46
Q

Coloboma

A

This defect involves an improper closing of the choroid fissure resulting in a gap in the iris or iris and retina

47
Q

Cyclopia

A

This defect occurs when there is fusion of the eye in the midline. Cyclopia is indicated by a single eye; synophthalmia is indicated when there is incomplete fusion of the eyes. Cyclopia results from a defect involving midline structures and is accompanied by other defects and is incompatible
with life. Cyclopia is often accompanied by a midline proboscis that is situated superior to the fused eye

48
Q

Microphthalmia

A

This defect is indicated by a small, normal appearing eye or an eye that was arrested at some point during normal development; may lack a lens

49
Q

Anophthalmia

A

This defect is indicated by the congenital absence of eye tissue. Can vary in severity – can involve only the optic stalk or may involve development of the forebrain

50
Q

Persistent pupillary membrane

A

The pupillary membrane normally covers the anterior surface of the lens and disappears during development. This membrane may remain as strands of connective
tissue spanning the pupil but will rarely interfere with vision

51
Q

Congenital glaucoma

A

Glaucoma is any increase in the intraocular pressure. This occurs congenitally when there is a defect in the draining mechanism (scleral venous sinus). This condition may arise in relation to a rubella infection during pregnancy

52
Q

Congenital cataract

A

Any lens opacity present at birth; can be progressive so may not be identified at birth; can be caused by infection (rubella, chicken pox, herpes) or genetic

53
Q

Aniridia

A

Absence of the iris; defect involving neuroectoderm and neural crest cells

54
Q

Color of the iris

A

Usually blue/gray in most newborns -> becomes primary color by 8-10 months

55
Q

Congenital aphakia

A

Absence of the lens

56
Q

Heterochromia

A

Different eye colors

57
Q

Retinoblastoma

A

a neuronal tumor arising from the retina; the most common primary intraocular malignancy of childhood

LECOM MS1 Gross Anatomy - Head/Neck 2022 (+Shelf) (29 decks)

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