Questions and Answers
What is formed during the first week of the germinal period after fertilization?
What process occurs during week 2 of the period of the ovum?
Which component of the blastocyst develops into the inner cell mass?
During the implantation process, what happens to the blastocyst?
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Which of the following statements is accurate regarding the morula?
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What is the primary function of the afferent central auditory pathway?
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Which structure is involved in the processing of auditory signals before they reach the auditory cortex?
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What type of hearing loss results from damage to the inner ear or auditory nerve?
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What is the main role of the efferent central auditory pathway?
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What is impedance matching in the context of hearing?
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Which part of the vestibulocochlear nerve is responsible for balance and spatial orientation?
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How does conductive hearing loss typically occur?
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Which of the following accurately describes the function of the cochlear nerve?
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What is the primary role of the stapedius muscle?
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Which cranial nerve innervates the tensor tympani muscle?
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What function does the oval window serve in the middle ear?
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Where is the canal for the tensor tympani located?
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What does the round window do in relation to acoustic energy?
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What is contained within the bony labyrinth?
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What substance does the epithelial lining of the bony labyrinth release?
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What structure is present on the medial wall of the middle ear?
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What is the main function of the ossicles in the ear?
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Which part of the malleus provides attachment to the tympanic membrane?
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Which layer of the tympanic membrane contains circular fibers primarily found at the periphery?
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What structure forms the communication link in the ossicular chain?
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Which ligament of the malleus is responsible for holding its head within the epitympanic recess?
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The long process of the Incus is most similar in direction to which part of the malleus?
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Which part of the malleus is associated with providing points of attachment for ligaments?
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Which part of the tympanic membrane is known as the cuticular layer?
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What is the size of the embryo at week 5 of development?
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Which development occurs at week 10 of fetal development?
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What important physiological function begins at week 12 of pregnancy?
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At what week does the fetus begin to develop hearing?
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During which week does the baby’s lanugo start to fall off?
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What size does the fetus reach by week 24?
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What is the primary focus of development in week 29?
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Which of the following developments occurs in week 26?
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At what week are the majority of fetal features developed?
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What structural change is happening to the bones by week 34?
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What significant change occurs in the fetus during week 20?
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Which sequence represents the correct development stages of the lip formation?
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What is the primary role of the muscular system?
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Study Notes
Human Embryology
Period of the Ovum (0 - 2 weeks)
- Fertilization: Sperm penetrates the egg, forming a zygote.
- Cleavage: Zygote divides into a morula (16-32 cells).
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Blastocyst Formation: The morula continues to divide, creating:
- Embryoblast: Inner cell mass.
- Trophoblast: Outer cell layer.
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Week 2 Events:
- Adplantation: Initial adhesion to uterine epithelium.
- Implantation: Blastocyst attaches to the uterine wall.
- Embedding: Blastocyst embeds into the uterine lining.
- Coagulation Plug: Forms at the implantation site.
Period of the Embryo (2 weeks - 2 months)
- Week 3: Features resembled from the Ovum period; zygote, morula, and blastocyst formation repeat.
- Week 4: Same events recur as in Week 3.
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Week 5:
- Size: 2mm, similar to a poppy seed.
- Development: Nervous system forms, heart begins to beat, neural tube develops.
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Week 6:
- Size: 6mm, resembling a pea.
- Initial limb dents form, bulges are visible for heart and head.
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Week 7:
- Size: 10mm, growing rapidly.
- Brain outgrows the body; inner ear begins development.
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Week 8:
- Size: 16mm, akin to a raspberry.
- Head uncurls; arms outgrow legs; embryo transitions to a fetus.
Period of the Fetus (2 months - birth)
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Week 9:
- Size: 22mm; human-like features begin to develop.
- Cartilage transitions into bone.
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Week 10:
- Size: 30mm; organogenesis occurs, forming organs from the three germ layers: ectoderm, mesoderm, endoderm.
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Week 11:
- Size: 41mm; further development of fetal features.
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Week 12:
- Completion of the first trimester; size is 5.4cm; kidneys function, and digestive system matures.
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Week 13:
- Size: 7.4cm; bonification begins.
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Weeks 14-16:
- Skin thickening; fingerprints formed; fetal hearing develops.
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Week 17:
- Skin covered with vernix, fetal reflexes start.
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Weeks 18-20:
- Size increase; senses develop, and organs transition to definitive positions.
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Weeks 21-23:
- Fetus gains weight; brain activity increases; limbs proportionate.
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Weeks 24-30:
- Lungs develop surfactant; first eye openings; rapid weight gain; sensory development peaks.
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Weeks 31-40:
- Final growth phases; bones harden, immune systems develop; fetus practices breathing; preparations for birth occur.
Developmental Disorders
- Treacher Collins Syndrome: Ear, eye, cheekbone, and chin deformities.
- Pierre Robin Sequence: Characterized by glossoptosis (backward positioned tongue) and micrognathia (underdevelopment of the jaw).
Muscle and Nerve Physiology
Mobility
- Muscular system enables movement via muscle contractions.
- Gross Movement: Larger coordinated motions; examples include walking and swimming.
- Fine Movement: Smaller, precise actions; examples include speaking and facial expressions.
Ossicles
- Components: Malleus, incus, stapes; crucial for transmitting sound.
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Malleus:
- Attaches to the tympanic membrane; carries vibrations to incus.
- Incus: Intermediate link in the ossicular chain.
- Stapes: Smallest bone; connects to the oval window for sound transmission.
Tympanic Muscles
- Stapedius Muscle: Reduces loud sounds; innervated by CN VII.
- Tensor Tympani: Dampens sounds; innervated by CN V.
Hearing Mechanisms
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Impedance Matching: Enhances sound energy transfer:
- Sound waves vibrate the tympanic membrane.
- Ossicles amplify pressure transfer to the oval window.
Hearing Impairments
- Sensorineural Hearing Loss: Damage to inner ear or auditory nerve.
- Conductive Hearing Loss: Obstruction in sound wave transmission in outer or middle ear.
- Mixed Hearing Loss: Combination of issues from different ear parts.
Auditory Pathways
- Afferent Pathway: Carries auditory info from the cochlea to brain.
- Efferent Pathway: Carries signals from the brain to cochlea, regulating auditory input.
Vestibulocochlear Nerve
- Sensory nerve for auditory and vestibular information to the brain.
- Cochlear Nerve: Transmits auditory signals.
- Vestibular Nerve: Carries balance information.
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Description
Human Embryology, Muscle & Nerve Physiology, and Hearing Mechanism
