Embryology: Development of Speech and Hearing Systems Flashcards

(43 cards)

1
Q

Embryology

A

Human Embryology is the study of human development during the first 8 weeks

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2
Q

Embryogenesis

A

The process of cell division and cellular differentiation of the human embryo that occurs during the early stages of development

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3
Q

How does human development begin and occur?

A

Occurs along a continuum

Begins with germ cells (ovum and spermatozoon) and progressing to growth to adulthood

After the first 8 weeks, the embryo is then referred to as a fetus

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4
Q

How many cells does a mature human body have?

A

10^14 cells

These cells will form and differentiate as the body grows

Some cells are replaced as they mature and die

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5
Q

What is the first step in cell division?

A

Duplication of genes and chromosomes

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6
Q

The process of development is characterized by?

A

The coordination of spatial and temporal changes in gene expression, cell growth or maturation, and cell differentiation

This process ultimately leads to the development of organs and systems

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7
Q

Prenatal Development Means

A

Development that occurs during the first 8 weeks of gestation

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8
Q

Prenatal Development - Week 2

A

The amniotic cavity develops, along with the primary germ or germinal layers of tissue:

Extoderm, mesoderm, and endoderm

These 3 layers of primary tissue ultimately give rise to all of the structures of the body

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9
Q

Ectoderm

A

Outer most layer and forms the epidermis of the skin, much of the teeth, the entire nervous system (both PNS and CNS), hair nails, and epithelial tissue

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10
Q

Mesoderm

A

The intermediate layer that ultimately gives rise to most of the connective tissue in the body.

In other words, it comprises the bones, muscles, blood vessels, and cartilages of the body

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11
Q

endoderm

A

Deepest of the three layers. It gives rise to the epithelial lining of the entire digestive tract and respiratory tract

except for the linings of the oral and pharyngeal cavities, which are formed by ectoderm

Endoderm is sometimes referred to as “inner skin”

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11
Q

Prenatal Development - 3rd week

A

The primitive streak appears, followed by rapid development of the CNS, heart, notochord, neural tube, limbs, digits, and facial features

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12
Q

Primitive Streak is comprised of

A

number of cells that proliferate caudally

Significance of the primitive streak is that it is capable of forming new germ tissue (ectoderm, mesoderm, and endoderm)

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13
Q

Notochord

A

Primitive axial (forming or relating to axis) skeleton of the embryo

Cephalically (of or related to the head), some tissues of the notochord will develop that will form the buccopharyngeal membrane

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14
Q

At 3 weeks, the facial area is

A

Very primitive (early stage)

Consists of smooth, relatively undifferentiated bulge known as the PROSENCEPHALON, which is the forebrain or anterior brain of the embryo

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15
Q

Caudal to the prosencephalon (forebrain) lies a?

A

Transverse furrow called the oral groove or stomodeum (primitive mouth)

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16
Q

STOMODEUM means

A

primitive mouth and is regarded as the center of the developing facial structures

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17
Q

At week 3, the ectoderm…

A

begins to thicken in an area immediately overlying the notochord

thickened layer of ectoderm is called the MEDULLARY or NEURAL PLATE - the lateral margins of which grow upward to form the NEURAL FOLDS

Eventually, the NEURAL FOLDS will meet at midline, fuse, and form the NEURAL TUBE

18
Q

Importance of the neural tube

A

Ultimately gives rise to the entire CNS, which comprises the brain and spinal cord

19
Q

3 subdivisions of neural tube

A
  1. prosencephalon
  2. mesencephalon
  3. rhombencephalon
20
Q

Prosencephalon

A

Subdivision of neural tube

will further develop into the telencephalon (cerebrum) + diencephalon (optic vessels + hypothalamus)

21
Q

Mesencephalon

A

Subdivision of neural tube

Will eventually develop into mid brain

22
Q

Rhombencephalon

A

subdivision of neural tube

Will eventually develop into metencephalon (pons and cerebellum) and the myencephalon (medulla oblongata)

23
Q

The 4th and final subdivision of the neural tube will form the ?

A

Spinal cord

Neural tube is open both cranially and caudally before finally closing during the 4th week of development

24
Openings in the neural tube called
Neuropores
25
Failure of the neuropores to properly close may result in
neural tube defects Example is spina bifida
26
In the 4th week, what happens to the buccopharyngeal membrane
It ruptures, allowing the stomodeum (primitive mouth or oral cavity) to articulate with the pharynx
27
4th week - migrating neural crest cells
These form the frontonasal process located in the anterior portion of the forebrain A number of neural crest cells will form the branchial or pharyngeal arches Together, the frontonasal process and branchial arches contribute greatly to the development of the FACE and ORAL CAVITY
28
4-5 week of development Branchial and Pharyngeal arches are comprised of what
6 paired thickenings that form a LATERAL PLATE
29
Mandibular Arch
First of the branchial arches Gives rise to the lower lip, the muscles of mastication, and mandible proper, the anterior portion of the tongue, malleus and incus, tensor tympani, tensor veli palatini, mylohyoid, and the anterior belly of digastric
30
Hyoid Arch
Second of the branchial arches Gives rise to the upper body and lesser horns of the hyoid bone, the stapes, the muscles of facial expression, stapedius, stylohyoid, and the posterior belly of digastric
31
Branchial arch 3
Gives rise to the lower body of the hyoid bone, the posterior portion of the tongue, and the stylopharyngeus
32
Branchial Arch 4
Cartilages of the larynx, all muscles of the larynx and pharynx except stylopharyngeus, and all muscles of the soft palate (except tensor veli palatini)
33
Branchial Arch 5 (mystery arch)
Some research suggests that it gives rise to the cricoid + arytenoid cartilages and the cartilages of the trachea HOWEVER, more recent research has suggested that the 5th arch disappears during embryonic development and does not give rise to any structures or muscles in human embryo development
34
Branchial Arch 6
Gives rise to the muscles sternocleidomastoid and trapezius
35
All Branchial arches are innervated (supplied with nerves) by the CN
First: Trigeminal (V) Second: Facial (VII) Third: Glossopharyngeal (IX) Fourth: Vagus (X) Sixth: Accessory (XI)
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5th week: frontonasal process
Rapidly develops caudally Gives rise to upper face, forehead, bridge o the nose, and nasal septum
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5th week - maxillary process
Develop and give rise to the maxilla
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5th week - mandibular process
Gives rise to the mandible
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6th week - maxillary and mandibular process can be distinguished from one another T/F?
True Towards the end of the 6th week of development, the hard and soft palates begin to develop
40
7th week - soft palate + hard palate
soft palate forms through the fusion of the medial nasal processes Hard palate forms through the fusion of the palatine processes of the maxillae + the horizontal lamina of the palatine bones These fusions complete the formation of the ceiling of the oral cavity and the floor of the nasal cavity
41
7-8 weeks - tongue formation
Tongue begins to form at about the same time as the hard and soft palates It extends from various protuberances along the pharyngeal floor It is derived from all pharyngeal arches contributing different components
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