Anatomy Prelim

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Questions and Answers

What is formed during the first week of the germinal period after fertilization?

Embryoblast

Zygote (correct)

Blastocyst

Morula (correct)

What process occurs during week 2 of the period of the ovum?

Organogenesis

Gastrulation

Coagulation Plug formation (correct)

Neurulation

Which component of the blastocyst develops into the inner cell mass?

Trophoblast

Zygote

Embryoblast (correct)

Morula

During the implantation process, what happens to the blastocyst?

It embeds itself into the uterine wall. Signup and view all the answers

Which of the following statements is accurate regarding the morula?

It can contain around 16 to 32 cells. Signup and view all the answers

What is the primary function of the afferent central auditory pathway?

Carries auditory information to the brain Signup and view all the answers

Which structure is involved in the processing of auditory signals before they reach the auditory cortex?

Thalamus Signup and view all the answers

What type of hearing loss results from damage to the inner ear or auditory nerve?

Sensorineural hearing loss Signup and view all the answers

What is the main role of the efferent central auditory pathway?

Carries signals from the brain to the cochlea Signup and view all the answers

What is impedance matching in the context of hearing?

Optimizing energy transfer to the inner ear Signup and view all the answers

Which part of the vestibulocochlear nerve is responsible for balance and spatial orientation?

Vestibular nerve Signup and view all the answers

How does conductive hearing loss typically occur?

From obstruction in the external or middle ear Signup and view all the answers

Which of the following accurately describes the function of the cochlear nerve?

Transmits auditory information from the cochlea to the brain Signup and view all the answers

What is the primary role of the stapedius muscle?

To reduce vibrations caused by loud sounds Signup and view all the answers

Which cranial nerve innervates the tensor tympani muscle?

CN V Signup and view all the answers

What function does the oval window serve in the middle ear?

It transmits sound from air to liquid Signup and view all the answers

Where is the canal for the tensor tympani located?

In the anterior wall of the middle ear Signup and view all the answers

What does the round window do in relation to acoustic energy?

Decompresses acoustic energy entering the cochlea Signup and view all the answers

What is contained within the bony labyrinth?

Vestibulocochlear organs Signup and view all the answers

What substance does the epithelial lining of the bony labyrinth release?

Perilymph Signup and view all the answers

What structure is present on the medial wall of the middle ear?

Oval window Signup and view all the answers

What is the main function of the ossicles in the ear?

To provide the means for transmission of acoustic energy to the inner ear Signup and view all the answers

Which part of the malleus provides attachment to the tympanic membrane?

Manubrium Signup and view all the answers

Which layer of the tympanic membrane contains circular fibers primarily found at the periphery?

Deep Layer Signup and view all the answers

What structure forms the communication link in the ossicular chain?

Incus Signup and view all the answers

Which ligament of the malleus is responsible for holding its head within the epitympanic recess?

Superior ligament Signup and view all the answers

The long process of the Incus is most similar in direction to which part of the malleus?

Manubrium Signup and view all the answers

Which part of the malleus is associated with providing points of attachment for ligaments?

Anterior lateral processes Signup and view all the answers

Which part of the tympanic membrane is known as the cuticular layer?

Outer Layer Signup and view all the answers

What is the size of the embryo at week 5 of development?

2mm long Signup and view all the answers

Which development occurs at week 10 of fetal development?

Organogenesis begins Signup and view all the answers

What important physiological function begins at week 12 of pregnancy?

Digestive system becomes functional Signup and view all the answers

At what week does the fetus begin to develop hearing?

Week 16 Signup and view all the answers

During which week does the baby’s lanugo start to fall off?

Week 32 Signup and view all the answers

What size does the fetus reach by week 24?

25.6 cm Signup and view all the answers

What is the primary focus of development in week 29?

Weight gain and noticeable kicks Signup and view all the answers

Which of the following developments occurs in week 26?

Lungs develop surfactant Signup and view all the answers

At what week are the majority of fetal features developed?

Week 31 Signup and view all the answers

What structural change is happening to the bones by week 34?

Skull remains soft while others harden Signup and view all the answers

What significant change occurs in the fetus during week 20?

Senses start developing Signup and view all the answers

Which sequence represents the correct development stages of the lip formation?

Medial nasal processes -> external nares -> maxillary processes Signup and view all the answers

What is the primary role of the muscular system?

Provide the ability to move Signup and view all the answers

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).
Blastocyst Formation: The morula continues to divide, creating:
- Embryoblast: Inner cell mass.
- Trophoblast: Outer cell layer.
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.
Week 5:
- Size: 2mm, similar to a poppy seed.
- Development: Nervous system forms, heart begins to beat, neural tube develops.
Week 6:
- Size: 6mm, resembling a pea.
- Initial limb dents form, bulges are visible for heart and head.
Week 7:
- Size: 10mm, growing rapidly.
- Brain outgrows the body; inner ear begins development.
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)

Week 9:
- Size: 22mm; human-like features begin to develop.
- Cartilage transitions into bone.
Week 10:
- Size: 30mm; organogenesis occurs, forming organs from the three germ layers: ectoderm, mesoderm, endoderm.
Week 11:
- Size: 41mm; further development of fetal features.
Week 12:
- Completion of the first trimester; size is 5.4cm; kidneys function, and digestive system matures.
Week 13:
- Size: 7.4cm; bonification begins.
Weeks 14-16:
- Skin thickening; fingerprints formed; fetal hearing develops.
Week 17:
- Skin covered with vernix, fetal reflexes start.
Weeks 18-20:
- Size increase; senses develop, and organs transition to definitive positions.
Weeks 21-23:
- Fetus gains weight; brain activity increases; limbs proportionate.
Weeks 24-30:
- Lungs develop surfactant; first eye openings; rapid weight gain; sensory development peaks.
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.
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

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