Block 5 Embryo Head Neck Eye Ear BRS W Exp
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- 1.
The most common site of a thyroglossal cyst is the
- A.
Dorsal aspect of neck
- B.
Anterior border of sternocleidomastoid muscle
- C.
Superior mediastinum
- D.
Midline close to the hyoid bone
- E.
Base of the tongue
Correct Answer
D. Midline close to the hyoid boneExplanation
The thyroid gland forms from a diverticulum in the midline of the floor of the pharynx.
The thyroid migrates caudally and passes ventral to the hyoid bone. During this migration, the thyroid remains connected to the tongue by the thyroglossal duct. If a part of the thyroglossal duct persists, a cyst develops, usually near the hyoid bone.Rate this question:
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- 2.
Taste sensation from the oral part (anterior two thirds) of the tongue is predominantly carried by the
- A.
Trigeminal nerve (CN V)
- B.
Chorda tympani branch of the facial nerve (CN VII)
- C.
Glossopharyngeal nerve (CN IX)
- D.
Superior laryngeal branch of the vagusnerve (CN X)
- E.
Recurrent laryngeal branch of the vagusnerve (CN X)
Correct Answer
B. Chorda tympani branch of the facial nerve (CN VII)Explanation
Taste sensation from the mucosa for the oral part of the tongue is carried by the chorda tympani branch of the facial nerve (CN VII). This part of the tongue forms from pharyngeal arch 1, so the trigeminal nerve (CN V) will carry sensory innervation from the mucosa.Rate this question:
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- 3.
The intermaxillary segment forms via the fusion of the
- A.
Maxillary prominences
- B.
Mandibular prominences
- C.
Palatine shelves
- D.
Lateral nasal prominences
- E.
Medial nasal prominences
Correct Answer
E. Medial nasal prominencesExplanation
The intermaxillary segment, which plays a critical role in the formation of the definitive adult palate, forms when the two medial nasal prominences fuse in the midline.Rate this question:
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- 4.
The most common site of a pharyngeal fistula is the
- A.
Dorsal aspect of neck
- B.
Anterior border of sternocleidomastoid muscle
- C.
Superior mediastinum
- D.
Midline close to the hyoid bone
- E.
Base of the tongue
Correct Answer
B. Anterior border of sternocleidomastoid muscleExplanation
A pharyngeal fistula forms when pharyngeal pouch 2 and pharyngeal groove 2 persist. Therefore, these fistulas are found on the lateral aspect of the neck, usually along the anterior border of the sternocleidomastoid muscle.Rate this question:
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- 5.
What is the most common congenital malformation of the head and neck region?
- A.
Anterior cleft palate
- B.
Posterior cleft palate
- C.
Thyroglossal duct cyst
- D.
Unilateral cleft lip
- E.
Ankyloglossia
Correct Answer
D. Unilateral cleft lipExplanation
Unilateral cleft lip is the most common congenital malformation of the head and neck. Cleft lip occurs when the maxillary prominences fail to fuse with the medial nasal prominences and when the underlying somitomeric mesoderm and neural crest fail to proliferate, resulting in a persistent labial groove. Cleft lip occurs in 1 of 900 births and may be unilateral or bilateralRate this question:
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- 6.
Which pharyngeal arch is associated with Treacher Collins syndrome?
- A.
Pharyngeal arch 1
- B.
Pharyngeal arch 2
- C.
Pharyngeal arch 3
- D.
Pharyngeal arch 4
- E.
Pharyngeal arch 6
Correct Answer
A. Pharyngeal arch 1Explanation
First arch syndrome results from abnormal development of pharyngeal arch 1 due to a lack of migration of neural crest cells. Treacher Collins syndrome is associated with underdevelopment of the zygomatic bone, down-slanting palpebral fissures, and deformed lower eyelids and external ears.Rate this question:
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- 7.
During surgery for removal of a thyroid tumor, a number of small masses of glandular tissue are noted just lateral to the thyroid gland. Metastasis from the thyroid tumor is suspected, but histologic analysis of a biopsy reveals parathyroid tissue and remnants of thymus. How can this finding be explained?
- A.
Tumor tissue has differentiated into normal tissue
- B.
A parathyroid gland tumor is also present
- C.
Ectopic glandular tissue is commonly found in this region
- D.
Patient has DiGeorge syndrome
- E.
The glandular tissue is a result of a thyroglossal duct cyst
Correct Answer
C. Ectopic glandular tissue is commonly found in this regionExplanation
The parathyroid and thymus migrate in a caudal and medial direction during development; therefore, ectopic glandular tissue may be found anywhere along the migratory path.Rate this question:
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- 8.
BRS EMBRYO EAR The cochlear duct contains the spiral organ of Corti and is derived from which of the following?
- A.
Both ectoderm and mesoderm
- B.
Neural crest
- C.
Endoderm
- D.
Mesoderm
- E.
Ectoderm
Correct Answer
E. EctodermExplanation
The cochlear duct is derived from a thickening of the surface ectoderm called the otic placode.Rate this question:
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- 9.
The middle ear cavity
- A.
Is of mesodermal origin
- B.
Develops from pharyngeal pouch 1
- C.
Develops from pharyngeal arch 1
- D.
Develops from pharyngeal arch 2
- E.
Develops from the otic vesicle
Correct Answer
B. Develops from pharyngeal pouch 1Explanation
The middle ear cavity develops from pharyngeal pouch 1 as it evaginates to form the tubotympanic
recess.Rate this question:
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- 10.
The otic vesicle
- A.
Gives rise to the bony labyrinth
- B.
Is found adjacent to the rhombencephalon
- C.
Is derived from neuroectoderm
- D.
Gives rise to the auricle (pinna)
- E.
Gives rise to the tympanic membrane
Correct Answer
B. Is found adjacent to the rhombencephalonExplanation
The otic vesicle arises from an invagination of the surface ectoderm called the otic placode.
The otic vesicle is found adjacent to the rhombencephalon.Rate this question:
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- 11.
The auricle (pinna) of the external ear is innervated by which of the following nerves?
- A.
CN V3
- B.
CN V2
- C.
CN XII
- D.
CN III
- E.
CN VIII
Correct Answer
A. CN V3Explanation
The auricle (pinna) of the external ear is innervated by cranial nerves V3 (mandibular division),
VII, IX, and X; cervical nerves C2 and C3 also innervate the auricle.Rate this question:
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- 12.
VThe stapedius muscle that moves the stapes ossicle is innervated by
- A.
CN V3
- B.
CN XII
- C.
CN III
- D.
CN VII
- E.
Cervical nerves C2 and C3
Correct Answer
D. CN VIIExplanation
The stapes is innervated by CN VII.Rate this question:
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- 13.
The utricular portion of the otic vesicle gives rise to the
- A.
Ductus reuniens
- B.
Cochlear duct
- C.
Endolymphatic sac
- D.
Scala vestibuli
- E.
Scala tympani
Correct Answer
C. Endolymphatic sacExplanation
The utricular region of the otic vesicle gives rise to the endolymphatic sac and duct, and
semicircular ducts.Rate this question:
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- 14.
The saccular portion of the otic vesicle gives rise to the
- A.
Organ of Corti
- B.
Endolymphatic duct
- C.
Superior semicircular canal
- D.
Crus commune nonampullare
- E.
Lateral semicircular canal
Correct Answer
A. Organ of CortiExplanation
The saccular region of the otic vesicle gives rise to the cochlear duct, which houses the spiral
organ of Corti.Rate this question:
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- 15.
The tubotympanic recess gives rise to
- A.
A conduit that interconnects the middle ear and the nasopharynx
- B.
The external auditory meatus
- C.
The internal auditory meatus
- D.
The facial canal
- E.
A conduit that interconnects the perilymphatic space with the subarachnoid space
Correct Answer
A. A conduit that interconnects the middle ear and the nasopharynxExplanation
The tubotympanic recess is derived from pharyngeal pouch 1. It gives rise to the tympanic
cavity and the auditory (eustachian) tube; the auditory tube interconnects the tympanic cavity
with the nasopharynx.Rate this question:
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- 16.
Perilymph enters the subarachnoid space via the
- A.
Cochlear duct
- B.
Ductus reuniens
- C.
Perilymphatic duct
- D.
Vestibular aqueduct
- E.
Utriculosaccular duct
Correct Answer
C. Perilymphatic ductExplanation
The perilymph enters the subarachnoid space of the posterior cranial fossa via the cochlear
aqueduct, which contains the perilymphatic duct.Rate this question:
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- 17.
Pharyngeal groove 1 gives rise to the
- A.
Internal auditory meatus
- B.
External auditory meatus
- C.
Eustachian tube
- D.
Cervical sinus
- E.
Primary tympanic cavity
Correct Answer
B. External auditory meatusExplanation
Pharyngeal groove 1 gives rise to the external auditory meatus.Rate this question:
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- 18.
BRS EMBRYO EYE The surface ectoderm gives rise to which of the following structures?
- A.
Dilator pupillae muscle
- B.
Retina
- C.
Lens
- D.
Sclera
- E.
Choroid
Correct Answer
C. LensExplanation
The lens forms from the lens placode that is induced by the optic cup.Rate this question:
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- 19.
Failure of the choroid fissure to close results in
- A.
Congenital detached retina
- B.
Congenital aniridia
- C.
Congenital aphakia
- D.
Coloboma iridis
- E.
Microphthalmos
Correct Answer
D. Coloboma iridisExplanation
Failure of the choroid (optic) fissure to close results in a cleft of the iris, a coloboma iridis. This defect may extend into the ciliary body, choroid, optic nerve, or retina. Congenital aphakia, absence of the lens, may result from defective development of the lens placode.Rate this question:
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- 20.
The optic cup is an evagination of which of the following?
- A.
Telencephalon
- B.
Diencephalon
- C.
Mesencephalon
- D.
Metencephalon
- E.
Myelencephalon
Correct Answer
B. DiencephalonExplanation
The optic cup and its derivatives, the retina and optic nerve, develop from the diencephalon.Rate this question:
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- 21.
The epithelium of the ciliary body is derived from
- A.
Ectoderm
- B.
Mesoderm
- C.
Endoderm
- D.
Neuroecloderm
- E.
Neural crest cells
Correct Answer
D. NeuroeclodermExplanation
The ciliary body is derived from the anterior two layers of the optic cup (neuroectoderm), which form the epithelium and form an anterior extension of the choroid (mesoderm).Rate this question:
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- 22.
Hyperoxygenation of premature infants may result in
- A.
Congenital glaucoma
- B.
Microphthalmia
- C.
Coloboma
- D.
Retrolental fibroplasia
- E.
Persistent pupillary membrane
Correct Answer
D. Retrolental fibroplasiaExplanation
Retrolental fibroplasia results from hyperoxygenation of premature infants. In premature infants, high oxygen concentration results in vaso-obliteration of the terminal arterioles, leading to hemorrhage and infarction of the retina. This phenomenon is peculiar to the incompletely vascularized peripheral retinaRate this question:
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- 23.
The optic nerve is a tract of the diencephalon that is not completely myelinated until
- A.
5 years after birth
- B.
2 years after birth
- C.
1 year after birth
- D.
3 weeks after birth
- E.
3 months after birth
Correct Answer
E. 3 months after birthExplanation
The axons of the optic nerve are not completely myelinated until 3 months after birth. Myelinated axons are normally not found in the retina. The optic nerve is not a true peripheral nerve but a tract of the diencephalon; when severed, the optic nerve does not regenerate.
Myelination in the CNS is accomplished by oligodendrocytes; oligodendrocytes are not found in the retina.Rate this question:
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- 24.
The hyaloid canal is found in the
- A.
Vitreous body
- B.
Choroid
- C.
Optic stalk
- D.
Ciliary body
- E.
Intraretinal space
Correct Answer
A. Vitreous bodyExplanation
The hyaloid canal (Cloquet's canal) is found in the vitreous body. In early development, a hyaloid artery passes through the vitreous body to perfuse the developing lens; in the late fetal period, this artery obliterates to form the hyaloid canal.Rate this question:
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- 25.
Aqueous humor is produced by the
- A.
Choroid plexus
- B.
Trahecular meshwork
- C.
Ciliary processes
- D.
Vitreous body
- E.
Lens vesicle
Correct Answer
C. Ciliary processesExplanation
Aqueous humor is produced by the ciliary processes of the ciliary body. It flows from the posterior chamber, through the pupil, into the anterior chamber, and finally to the canal of Schlemm, which empties into the extraocular veins.Rate this question:
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- 26.
Aqueous humor enters the venous circulation via
- A.
Arachnoid villi
- B.
Scleral canal
- C.
Hyaloid canal
- D.
Canal of Schlemm
- E.
Cloquet's canal
Correct Answer
D. Canal of SchlemmExplanation
Aqueous humor enters the venous circulation via the canal of Schlemm. Blockage of this canal results in increased intraocular pressure (glaucoma).Rate this question:
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- 27.
In a detached retina, the site of detachment is found
- A.
Within the outer plexiform layer
- B.
Within the inner plexiform layer
- C.
Between the inner nuclear layer and the outer nuclear layer
- D.
Between the choriocapillaris and the pigmentepithelial layer
- E.
Between the pigment epithelial layer and the layer of outer segments of rods and cones
Correct Answer
E. Between the pigment epithelial layer and the layer of outer segments of rods and conesExplanation
The site of retinal detachment is between the pigment epithelial layer and the layer of outer segments M rods and cones; this corresponds to the intraretinal space between the inner and outer layers of the optic cup. Retinal detachment occurs when fluid from the vitreous compartment passes through a retinal hole and separates the pigment epithelial layer from the layer of outer segments of rods and cones.Rate this question:
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Mar 19, 2023Quiz Edited by
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Feb 18, 2012Quiz Created by
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