Ear structure and the Labyrinth
Inner Ear
Middle Ear
External Ear
Clinical Considerations
100
The membranous Labyrinth consists of all the structures derived from where?
The Otic Vesicle
100
Which structure separates the cochlear duct from the scala tympani, and what is its significance in the auditory process?
A. Reissner's membrane; it transmits sound vibrations to the scala tympani
B. Basilar membrane; it supports the organ of Corti and plays a key role in sound frequency discrimination
C. Tectorial membrane; it vibrates in response to sound and separates the cochlear duct from the scala tympani
D. Vestibular membrane; it maintains the ionic balance of the cochlear fluids
B. Basilar membrane; it supports the organ of Corti and plays a key role in sound frequency discrimination
100
This cartilage from the first pharyngeal arch gives rise to both the malleus and incus.
Meckel's cartilage
100
By the end of which embryonic week is the external ear's basic structure recognizable?
By the 10th week of development.
100
Minor auricular malformations are commonly found and raise only cosmetic issues. However, auricular malformations are seen in different types of syndromes
Which three syndromes show signs of minor auricularis malformations?
Down syndrome (trisomy 21), Patau syndrome (trisomy 13), and Edwards syndrome (trisomy18).
200
State the three parts of the ear and their general functions
The external ear - the sound-collecting organ
The middle ear - a sound conductor from the external to the internal ear
The internal ear - converts sound waves into nerve impulses and registers changes in equilibrium
200
During the formation of the otic vesicle, the statoacoustic ganglion develops from a small group of cells that break away from its wall and from neural crest cells. Which of the following correctly describes the development and function of the statoacoustic ganglion?
A. It splits into cochlear and vestibular portions, supplying sensory cells of the organ of Corti, saccule, utricle, and semicircular canals.
B. It differentiates entirely from the otic vesicle and solely innervates the cochlear sensory cells.
C. It forms from the neural crest exclusively and provides sensory input to the vestibular portion of the inner ear.
D. It splits into cochlear and vestibular portions, with the cochlear portion supplying the semicircular canals and the vestibular portion supplying the organ of Corti.
A. It splits into cochlear and vestibular portions, supplying sensory cells of the organ of Corti, saccule, utricle, and semicircular canals.
200
These two cranial nerves provide innervation to the tympanic membrane.
Cranial Nerve V3 (trigeminal) and Cranial Nerve IX (glossopharyngeal)
200
What is the origin of the six auricular hillocks, and how do they contribute to the external ear's development?
The six auricular hillocks arise from mesenchymal tissue of the first (mandibular) and second (hyoid) pharyngeal arches. The three hillocks from the first arch form the tragus, helical crus, and part of the helix, while the three hillocks from the second arch form the antihelix, antitragus, and concha.
200
Congenital deafness: The organ of Corti may be damaged by exposure to rubella virus, especially during which week of development?
Weeks 7 and 8 of development.
300
The membranous labyrinth is initially surrounded by neural crest cells that form a connective tissue (mesenchyme) covering.
What occurs leading up to the anatomical relationship by which the membranous labyrinth is suspended within the bony labyrinth by perilymph?
The connective tissue covering (layer) becomes cartilaginous and then ossifies to become the bony labyrinth of the temporal bone.
The connective tissue closest to the membranous labyrinth degenerates, thus forming the perilymphatic space containing perilymph.
300
Which of the following statements are true about the otic placode?
1. The otic placode is a thickened area of ectoderm in the early embryo.
2. The otic placode invaginates into the connective tissue adjacent to the diencephalon
3. The otic placode forms otocysts
4. The otic placode is a thickened area of mesoderm in the early embryo.
A) 1 & 2
B) 1 & 3
C) 2 & 3
D) 2 & 4
Correct Answers 1 & 3
300
Describe the detailed embryological process by which the primitive tympanic cavity develops from the tubotympanic recess, including its specific origin and lateral expansion.
The primitive tympanic cavity develops from the distal part of pharyngeal pouch 1, which expands laterally and comes into contact with the floor of the first pharyngeal cleft. The tubotympanic recess widens to form this primitive middle ear cavity, while its proximal portion remains narrow and differentiates into the auditory (Eustachian) tube.
ensure to have these in answer:
Origin from pharyngeal pouch 1
Lateral expansion
Contact with first pharyngeal cleft floor
Transformation of tubotympanic recess
Differentiation into middle ear cavity and auditory tube)
300
Describe the development and embryological origin of the tympanic membrane.
The tympanic membrane forms at the junction of the ectoderm from the first pharyngeal groove, the endoderm from the first pharyngeal pouch, and mesoderm in between. It serves as the boundary between the external ear and middle ear.
300
Name and describe this condition:
Microtia (small and malformed ear)- is a severely disorganized auricle that is associated with other malformations resulting in deafness. The embryological basis is impaired proliferation or fusion of the auricular hillocks.