Anatomy - Embryology of the Special Senses

A. Lens of the Eye

What is the fate of this embryonic structure: Optic Placodes?

A. Lens of the Eye

B. Nasal Cavity and Nose

C. Inner Ear (Semicircular Canals and Cochlea)

C. Inner Ear (Semicircular Canals and Cochlea)

What is the fate of this embryonic structure: Otic Placodes?

A. Lens of the Eye

B. Nasal Cavity and Nose

C. Inner Ear (Semicircular Canals and Cochlea)

B. Nasal Cavity and Nose

What is the fate of this embryonic structure: Olfactory Placodes?

A. Lens of the Eye

B. Nasal Cavity and Nose

C. Inner Ear (Semicircular Canals and Cochlea)

B. Optic Cup

What is the embryonic structure of this adult derivative: Globe of the eye & its Retina, Ciliary Body, and Iris (+ Pupil)?

A. Optic Stalk

B. Optic Cup

C. Optic Placode

D. Mesoderm (Paraxial: VLL cells of Somitomeres 1;2;3 & 5)

E. Invading Mesoderm Cells

F. Neural Crest Cells

G. Surface Ectoderm Cells

A. Optic Stalk

What is the embryonic structure of this adult derivative: Optic Nerve (Cranial Nerve II) to include optic tract & optic chiasm?

A. Optic Stalk

B. Optic Cup

C. Optic Placode

D. Mesoderm (Paraxial: VLL cells of Somitomeres 1;2;3 & 5)

E. Invading Mesoderm Cells

F. Neural Crest Cells

G. Surface Ectoderm Cells

C. Optic Placode

What is the embryonic structure of this adult derivative: Lens of the Eye?

A. Optic Stalk

B. Optic Cup

C. Optic Placode

D. Mesoderm (Paraxial: VLL cells of Somitomeres 1;2;3 & 5)

E. Invading Mesoderm Cells

F. Neural Crest Cells

G. Surface Ectoderm Cells

F. Neural Crest Cells

What is the embryonic structure of this adult derivative: Dilator pupillae & Constrictor pupillae muscles of iris?

A. Optic Stalk

B. Optic Cup

C. Optic Placode

D. Mesoderm (Paraxial: VLL cells of Somitomeres 1;2;3 & 5)

E. Invading Mesoderm Cells

F. Neural Crest Cells

G. Surface Ectoderm Cells

D. Mesoderm (Paraxial: VLL cells of Somitomeres 1;2;3 & 5)

What is the embryonic structure of this adult derivative: Extraocular Muscles (EOM) of the Eye?

A. Optic Stalk

B. Optic Cup

C. Optic Placode

D. Mesoderm (Paraxial: VLL cells of Somitomeres 1;2;3 & 5)

E. Invading Mesoderm Cells

F. Neural Crest Cells

G. Surface Ectoderm Cells

E. Invading Mesoderm Cells

What is the embryonic structure of this adult derivative: Ciliary Muscles?

A. Optic Stalk

B. Optic Cup

C. Optic Placode

D. Mesoderm (Paraxial: VLL cells of Somitomeres 1;2;3 & 5)

E. Invading Mesoderm Cells

F. Neural Crest Cells

G. Surface Ectoderm Cells

E. Invading Mesoderm Cells

What is the embryonic structure of this adult derivative: Hyaloid Blood Vessels / Central Blood Vessels of the Retina?

A. Optic Stalk

B. Optic Cup

C. Optic Placode

D. Mesoderm (Paraxial: VLL cells of Somitomeres 1;2;3 & 5)

E. Invading Mesoderm Cells

F. Neural Crest Cells

G. Surface Ectoderm Cells

E. Invading Mesoderm Cells

What is the embryonic structure of this adult derivative: Vitreous Body/Humor?

A. Optic Stalk

B. Optic Cup

C. Optic Placode

D. Mesoderm (Paraxial: VLL cells of Somitomeres 1;2;3 & 5)

E. Invading Mesoderm Cells

F. Neural Crest Cells

G. Surface Ectoderm Cells

G. Surface Ectoderm Cells

What is the embryonic structure of this adult derivative: Upper and Lower Eyelids plus Eyelashes (or Cilia) to include first 2 layers of the Cornea?

A. Optic Stalk

B. Optic Cup

C. Optic Placode

D. Mesoderm (Paraxial: VLL cells of Somitomeres 1;2;3 & 5)

E. Invading Mesoderm Cells

F. Neural Crest Cells

G. Surface Ectoderm Cells

B. Somitomeres 3

What is the embryonic structure of this adult derivative: Superior Oblique?

A. Somitomeres 1 & 2

B. Somitomeres 3

C. Somitomeres 5

C. Somitomeres 5

What is the embryonic structure of this adult derivative: Lateral Rectus?

A. Somitomeres 1 & 2

B. Somitomeres 3

C. Somitomeres 5

A. Somitomeres 1 & 2

What is the embryonic structure of this adult derivative: Medial Rectus, Inferior Oblique, Superior Rectus, Inferior Rectus?

A. Somitomeres 1 & 2

B. Somitomeres 3

C. Somitomeres 5

A. 7 o’ clock position

The choroid fissure is a temporary cleft found in what position of the left eye (O.S. or Oculus Sinister)?

A. 7 o’ clock position

B. 5 o’ clock position

B. 5 o’ clock position

The choroid fissure is a temporary cleft found in what position of the right eye (O.D. or Oculus Dexter)?

A. 7 o’ clock position

B. 5 o’ clock position

Coloboma Iridis

These temporary clefts (choroid fissure) will close as early as 7th week from time of fertilization. And if these choroid fissures fail to close it could lead to a congenital defect called?

A. Pars Ceca Retinae

Anterior 1/5 of the Optic Cup

A. Pars Ceca Retinae

B. Pars Optica Retinae

B. Pars Optica Retinae

Posterior 4/5 of the Optic Cup

A. Pars Ceca Retinae

B. Pars Optica Retinae

A. Outer pigment layer

What is the embryonic structure of this adult derivative: Will become the 10th layer of the retina?

A. Outer pigment layer

B. Inner neural layer

B. Inner neural layer

What is the embryonic structure of this adult derivative: Will differentiate into 1st nine layers of the retina?

A. Outer pigment layer

B. Inner neural layer

A. Sclera

UNDIFFERENTIATED MESODERM LAYER which is comparable to MESODERM LAYER that will form the “dura mater” of the Brain

A. Sclera

B. Choroid

B. Choroid

UNDIFFERENTAITED MESODERM LAYER which is comparable to MESODERM LAYER that will form the “pia mater” and “arachnoid mater” of the Brain

A. Sclera

B. Choroid

B. Last-to-Form

10th layer of the retina called RETINAL PIGMENT EPITHELIUM

A. First-to-Form

B. Last-to-Form

A. First-to-Form

1st or innermost layer of the retina called INNER LIMITING MEMBRANE

A. First-to-Form

B. Last-to-Form

A. First-to-Form

That part of the Retina near the “optic disk” called Macula

A. First-to-Form

B. Last-to-Form

B. Last-to-Form

That part of the Retina near the “pars ceca retinae” (that will become the iris and ciliary body)

A. First-to-Form

B. Last-to-Form

B. Retina

Vertical – Horizontal Theory

A. Cornea

B. Retina

C. Eyelids

A. Cornea

Hydration – Dehydration Theory

A. Cornea

B. Retina

C. Eyelids

C. Eyelids

Open – Close – Open Hypothesis

A. Cornea

B. Retina

C. Eyelids

B. Pars Ceca Retinae

What is the embryonic structure of the Iris & Ciliary Body (anterior 1/5th of Optic Cup)?

A. Pars Optica Retinae

B. Pars Ceca Retinae

A. Pars Optica Retinae

What is the embryonic structure of the Retina (posterior 4/5th’s of Optic Cup)?

A. Pars Optica Retinae

B. Pars Ceca Retinae

A. Pars iridica retinae

What is the embryonic structure of the Iris?

A. Pars iridica retinae

B. Pars ciliaris retinae

B. Pars ciliaris retinae

What is the embryonic structure of the Ciliary Body & Ciliary Muscles with Fibers of Zinn?

A. Pars iridica retinae

B. Pars ciliaris retinae

C. Pars Plana

What is the sub-parses of the cilirais retinae specifically the Structural anterior border of Vitreous Body?

A. Pars Muscularis

B. Pars Plicata NON-PIGMENTED EPITHELIUM

C. Pars Plana

B. Pars Plicata NON-PIGMENTED EPITHELIUM

What is the sub-parses of the cilirais retinae Responsible for synthesis, ultrafiltration, and secretion of Aqueous Humor. Responsible for the formation of Zonules of Zinn?

A. Pars Muscularis

B. Pars Plicata NON-PIGMENTED EPITHELIUM

C. Pars Plana

A. Pars Muscularis

What is the sub-parses of the cilirais retinae For the formation of Ciliary Muscles from extra VLL cells (i.e. Longitudinal; Radial; and Circular muscles)?

A. Pars Muscularis

B. Pars Plicata NON-PIGMENTED EPITHELIUM

C. Pars Plana

A. Proximal ½ of Hyaloid Artery

What is the blood supply of optic stalk to optic nerve?

A. Proximal ½ of Hyaloid Artery

B. Distal ½ of Hyaloid Artery

B. Distal ½ of Hyaloid Artery

What is the blood supply of posterior capsule of the lens, first 9 layers of the retina, and vitreous body from Week 4 to Week 6 only?

A. Proximal ½ of Hyaloid Artery

B. Distal ½ of Hyaloid Artery

C. Choroid

What primordial structure is the Main source of nutrition for 10th layer of the retina (this structure is Comparable to pia mater & arachnoid)?

A. Hyaloid artery (proximal)

B. Sclera

C. Choroid

D. Hyaloid artery (distal)

B. Sclera

What primordial structure is Comparable to dura mater?

A. Hyaloid artery (proximal)

B. Sclera

C. Choroid

D. Hyaloid artery (distal)

D. Hyaloid artery (distal)

What primordial structure is the Main source of nutrition for the inner 9 layers of the retina, posterior aspect of the lens, forming optic nerve & its plasma contributes in the formation of Vitreous Body and Humor formation?

A. Hyaloid artery (proximal)

B. Sclera

C. Choroid

D. Hyaloid artery (distal)

A. Hyaloid artery (proximal)

What primordial structure Will transform into Central Artery of Retina (CRA)?

A. Hyaloid artery (proximal)

B. Sclera

C. Choroid

D. Hyaloid artery (distal)

B. PAX-6

Master gene for “Eye” formation

A. PAX-2

B. PAX-6

C. SHH + PAX-2

D. none

B. PAX-6

Master gene for further “Lens” invagination, formation and maturation

A. PAX-2

B. PAX-6

C. SHH + PAX-2

D. none

A. PAX-2

Master gene for “Optic Nerve” formation

A. PAX-2

B. PAX-6

C. SHH + PAX-2

D. none

D. none

Gene needed for the start of the invagination of lens placode

A. PAX-2

B. PAX-6

C. SHH + PAX-2

D. none

C. SHH + PAX-2

Genes needed for separation of “single eye field” into two eye fields

A. PAX-2

B. PAX-6

C. SHH + PAX-2

D. none

A. FGF’s

Gene which determines “inner neural layer” of the optic vesicle/cup

A. FGF’s

B. TGF-b

B. TGF-b

Gene which determines “outer pigment layer” of the optic vesicle/cup

A. FGF’s

B. TGF-b

B. CHX-10

Gene which induces “inner neural layer” to become the first 9 layers of the Retina

A. MITF

B. CHX-10

C. CRX

C. CRX

Master gene for rods and cones formation

A. MITF

B. CHX-10

C. CRX

A. MITF

Gene which induces “outer pigment layer” to become the 10th layer of the Retina

A. MITF

B. CHX-10

C. CRX

A. Berger’s Space

Hollow space at the anterior end of the Hyaloid Canal

A. Berger’s Space

B. Cloquet’s Canal

C. Martigiani Space

D. Bergmeister’s Papilla

E. Mittendorf’s Dot

F. Weigert’s Ligamnet

G. Hyalocytes of Balaz’s

B. Cloquet’s Canal

Space left by the distal ½ of the Hyaloid Artery

A. Berger’s Space

B. Cloquet’s Canal

C. Martigiani Space

D. Bergmeister’s Papilla

E. Mittendorf’s Dot

F. Weigert’s Ligamnet

G. Hyalocytes of Balaz’s

C. Martigiani Space

Hollow space at the posterior end of the Hyaloid Canal in front of the Optic Disk

A. Berger’s Space

B. Cloquet’s Canal

C. Martigiani Space

D. Bergmeister’s Papilla

E. Mittendorf’s Dot

F. Weigert’s Ligamnet

G. Hyalocytes of Balaz’s

D. Bergmeister’s Papilla

Fibrous sheath-remnant of the distal ½ of the Hyaloid Artery

A. Berger’s Space

B. Cloquet’s Canal

C. Martigiani Space

D. Bergmeister’s Papilla

E. Mittendorf’s Dot

F. Weigert’s Ligamnet

G. Hyalocytes of Balaz’s

E. Mittendorf’s Dot

Point-of-Attachment or the “dot” left by the Hyaloid Artery behind the Lens

A. Berger’s Space

B. Cloquet’s Canal

C. Martigiani Space

D. Bergmeister’s Papilla

E. Mittendorf’s Dot

F. Weigert’s Ligamnet

G. Hyalocytes of Balaz’s

F. Weigert’s Ligament

Membrane that separates the Vitreous Body/Humor and back part of the Lens

A. Berger’s Space

B. Cloquet’s Canal

C. Martigiani Space

D. Bergmeister’s Papilla

E. Mittendorf’s Dot

F. Weigert’s Ligamnet

G. Hyalocytes of Balaz’s

G. Hyalocytes of Balaz’s

Considered “phagocytes” of the Vitreous Body/Humor that leads to continued breakdown and renewal of Hyaluronic Acid of the Vitreous Humor

A. Berger’s Space

B. Cloquet’s Canal

C. Martigiani Space

D. Bergmeister’s Papilla

E. Mittendorf’s Dot

F. Weigert’s Ligamnet

G. Hyalocytes of Balaz’s

I. Coloboma

Failure of the choroid fissure to close as early as 7th week

H. Cyclopia

I. Coloboma

J. Aniridia

K. Aphakia

L. Cryptophthalmos

M. Corectopia

N. Dyscoria

O. Cataract

P. Leukoma

H. Cyclopia

Failure to separate “single eye field” into 2 optic primordia

H. Cyclopia

I. Coloboma

J. Aniridia

K. Aphakia

L. Cryptophthalmos

M. Corectopia

N. Dyscoria

O. Cataract

P. Leukoma

K. Aphakia

Absence of lens

H. Cyclopia

I. Coloboma

J. Aniridia

K. Aphakia

L. Cryptophthalmos

M. Corectopia

N. Dyscoria

O. Cataract

P. Leukoma

J. Aniridia

Absence of iris

H. Cyclopia

I. Coloboma

J. Aniridia

K. Aphakia

L. Cryptophthalmos

M. Corectopia

N. Dyscoria

O. Cataract

P. Leukoma

L. Cryptophthalmos

Fused eyelids

H. Cyclopia

I. Coloboma

J. Aniridia

K. Aphakia

L. Cryptophthalmos

M. Corectopia

N. Dyscoria

O. Cataract

P. Leukoma

M. Corectopia

Displacement of the pupil far from center

H. Cyclopia

I. Coloboma

J. Aniridia

K. Aphakia

L. Cryptophthalmos

M. Corectopia

N. Dyscoria

O. Cataract

P. Leukoma

N. Dyscoria

Abnormal shape of the pupil but still falls on the center

I. Coloboma

J. Aniridia

K. Aphakia

L. Cryptophthalmos

M. Corectopia

N. Dyscoria

O. Cataract

P. Leukoma

O. Cataract

Opacification of the lens

I. Coloboma

J. Aniridia

K. Aphakia

L. Cryptophthalmos

M. Corectopia

N. Dyscoria

O. Cataract

P. Leukoma

P. Leukoma

Opacification of the cornea

I. Coloboma

J. Aniridia

K. Aphakia

L. Cryptophthalmos

M. Corectopia

N. Dyscoria

O. Cataract

P. Leukoma

C. Complete

One iris is of different color from the other

A. Sectora/Segmental

B. Central

C. Complete

A. Sectora/Segmental

Part of one iris is a different color from its remainder

A. Sectora/Segmental

B. Central

C. Complete

B. Central

There are spikes of different hues radiating from the pupil

A. Sectora/Segmental

B. Central

C. Complete

Fraser-Francois-Feichtiger-Meyer-Ullrich-Schwickerath Syndrome

A multisystem congenital condition primarily involving the eyes and genitalia, stemming from defective expression of the FRAS1 gene.

A. NCC + free cells of the Medial Wall of the Otocyst

What embryonic structure Will become Statoacoutic/Vestibulocochlear ganglion?

A. NCC + free cells of the Medial Wall of the Otocyst

B. Otic Placode

C. Dorsal Compartment of Otocyst (utricle)

D. Ventral Compartment of Otocyst (saccule)

B. Otic Placode

What embryonic structure Will become the inner ear?

A. NCC + free cells of the Medial Wall of the Otocyst

B. Otic Placode

C. Dorsal Compartment of Otocyst (utricle)

D. Ventral Compartment of Otocyst (saccule)

C. Dorsal Compartment of Otocyst (utricle)

What embryonic structure Will become the semicircular canals + endolymphatic duct and sac?

A. NCC + free cells of the Medial Wall of the Otocyst

B. Otic Placode

C. Dorsal Compartment of Otocyst (utricle)

D. Ventral Compartment of Otocyst (saccule)

D. Ventral Compartment of Otocyst (saccule)

What embryonic structure Will participate in the formation of the cochlea?

A. NCC + free cells of the Medial Wall of the Otocyst

B. Otic Placode

C. Dorsal Compartment of Otocyst (utricle)

D. Ventral Compartment of Otocyst (saccule)

A. Germ layers of 1st pharyngeal membrane + 1st pharyngeal cleft + 1st pharyngeal pouch

What embryonic structure Will become the “eardrum”?

A. Germ layers of 1st pharyngeal membrane + 1st pharyngeal cleft + 1st pharyngeal pouch

B. Utricle

C. 1st pharyngeal pouch only

D. Saccule

E. Six Auricular Hillocks

F. Otic Placode

G. NCC + medial wall cells of otic vesicle/otocyst

G. NCC + medial wall cells of otic vesicle/otocyst

What embryonic structure Will become “Statoacoutic ganglion”?

A. Germ layers of 1st pharyngeal membrane + 1st pharyngeal cleft + 1st pharyngeal pouch

B. Utricle

C. 1st pharyngeal pouch only

D. Saccule

E. Six Auricular Hillocks

F. Otic Placode

G. NCC + medial wall cells of otic vesicle/otocyst

F. Otic Placode

What embryonic structure Will become the “inner ear”?

A. Germ layers of 1st pharyngeal membrane + 1st pharyngeal cleft + 1st pharyngeal pouch

B. Utricle

C. 1st pharyngeal pouch only

D. Saccule

E. Six Auricular Hillocks

F. Otic Placode

G. NCC + medial wall cells of otic vesicle/otocyst

E. Six Auricular Hillocks

What embryonic structure Will become the external ear called “pinna”?

A. Germ layers of 1st pharyngeal membrane + 1st pharyngeal cleft + 1st pharyngeal pouch

B. Utricle

C. 1st pharyngeal pouch only

D. Saccule

E. Six Auricular Hillocks

F. Otic Placode

G. NCC + medial wall cells of otic vesicle/otocyst

B. Utricle

What embryonic structure Will become the “semicircular canals”?

A. Germ layers of 1st pharyngeal membrane + 1st pharyngeal cleft + 1st pharyngeal pouch

B. Utricle

C. 1st pharyngeal pouch only

D. Saccule

E. Six Auricular Hillocks

F. Otic Placode

G. NCC + medial wall cells of otic vesicle/otocyst

D. Saccule

What embryonic structure Will become the “cochlea”?

A. Germ layers of 1st pharyngeal membrane + 1st pharyngeal cleft + 1st pharyngeal pouch

B. Utricle

C. 1st pharyngeal pouch only

D. Saccule

E. Six Auricular Hillocks

F. Otic Placode

G. NCC + medial wall cells of otic vesicle/otocyst

C. 1st pharyngeal pouch only

What embryonic structure Will become the “tympanic cavity” and “Eustachian tube”?

A. Germ layers of 1st pharyngeal membrane + 1st pharyngeal cleft + 1st pharyngeal pouch

B. Utricle

C. 1st pharyngeal pouch only

D. Saccule

E. Six Auricular Hillocks

F. Otic Placode

G. NCC + medial wall cells of otic vesicle/otocyst

B. Meckel’s

Cartilage inside “Mandibular Compartment of 1st Pharyngeal Arch”

A. Reichert’s

B. Meckel’s

A. Reichert’s

Cartilage inside “2nd Pharyngeal Arch”

A. Reichert’s

B. Meckel’s

B. Alternative Theory

Stapes + handle/manubrium of malleus + long crus/process of incus are from 2nd Pharyngeal Arch (Reichert’s) and the remaining parts of Malleus and Incus are from 1st Pharyngeal Arch (Meckel’s)

A. Traditional Theory

B. Alternative Theory

A. Traditional Theory

The whole Malleus + the whole Incus are from 1st Pharyngeal Arch (Meckel’s) and the whole Stapes is a derived from 2nd Pharyngeal Arch (Reichert’s)

A. Traditional Theory

B. Alternative Theory

G. Tympanic cavity & Eustachian tube

What is the adult derivative of the First Pharyngeal pouch?

A. Palatine tonsils & Tonsillar fossa

B. Parathyroid gland, superior

C. Parathyroid gland, inferior

D. Marks Thyroid gland formation

E. Parafollicular cells/ “C” cells of Ultimobranchial body

F. Thymus

G. Tympanic cavity & Eustachian tube

A. Palatine tonsils & Tonsillar fossa

What is the adult derivative of the Second Pharyngeal pouch?

A. Palatine tonsils & Tonsillar fossa

B. Parathyroid gland, superior

C. Parathyroid gland, inferior

D. Marks Thyroid gland formation

E. Parafollicular cells/ “C” cells of Ultimobranchial body

F. Thymus

G. Tympanic cavity & Eustachian tube

C. Parathyroid gland, inferior

What is the adult derivative of the Third Pharyngeal pouch, dorsal wing?

A. Palatine tonsils & Tonsillar fossa

B. Parathyroid gland, superior

C. Parathyroid gland, inferior

D. Marks Thyroid gland formation

E. Parafollicular cells/ “C” cells of Ultimobranchial body

F. Thymus

G. Tympanic cavity & Eustachian tube

F. Thymus

What is the adult derivative of the Third Pharyngeal pouch, ventral wing?

A. Palatine tonsils & Tonsillar fossa

B. Parathyroid gland, superior

C. Parathyroid gland, inferior

D. Marks Thyroid gland formation

E. Parafollicular cells/ “C” cells of Ultimobranchial body

F. Thymus

G. Tympanic cavity & Eustachian tube

B. Parathyroid gland, superior

What is the adult derivative of the Fourth Pharyngeal pouch, dorsal wing?

A. Palatine tonsils & Tonsillar fossa

B. Parathyroid gland, superior

C. Parathyroid gland, inferior

D. Marks Thyroid gland formation

E. Parafollicular cells/ “C” cells of Ultimobranchial body

F. Thymus

G. Tympanic cavity & Eustachian tube

E. Parafollicular cells/ “C” cells of Ultimobranchial body

What is the adult derivative of the Fourth Pharyngeal pouch, ventral wing?

A. Palatine tonsils & Tonsillar fossa

B. Parathyroid gland, superior

C. Parathyroid gland, inferior

D. Marks Thyroid gland formation

E. Parafollicular cells/ “C” cells of Ultimobranchial body

F. Thymus

G. Tympanic cavity & Eustachian tube

D. Marks Thyroid gland formation

What is the adult derivative of the “Foramen cecum”?

A. Palatine tonsils & Tonsillar fossa

B. Parathyroid gland, superior

C. Parathyroid gland, inferior

D. Marks Thyroid gland formation

E. Parafollicular cells/ “C” cells of Ultimobranchial body

F. Thymus

G. Tympanic cavity & Eustachian tube

A. external ear canal/auditory meatus

What is the fate of First Pharyngeal cleft?

A. external ear canal/auditory meatus

B. DEGENERATES

C. ear drum

B. DEGENERATES

What is the fate of Second Pharyngeal cleft?

A. external ear canal/auditory meatus

B. DEGENERATES

C. ear drum

B. DEGENERATES

What is the fate of Third Pharyngeal cleft?

A. external ear canal/auditory meatus

B. DEGENERATES

C. ear drum

B. DEGENERATES

What is the fate of Fourth Pharyngeal cleft?

A. external ear canal/auditory meatus

B. DEGENERATES

C. ear drum