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Anatomy YR1 > Embryology of head and neck > Flashcards

Embryology of head and neck Flashcards

1
Q

3 regions of mesoderm

A

Paraxial mesoderm
Lateral plate mesoderm
Intermediate mesoderm

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2
Q

What is paraxial mesoderm

A

Thicked plate of tissue either side of midline

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3
Q

What is lateral plate mesoderm

A

divdes into two layers
Somatic/partietal mesoderm
Splanchin/visceral mesoderm
Line the intaembryonic cavity

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4
Q

What is intermediate mesoderm

A

Connects the paraxial and lateral plate mesoderm

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5
Q

What is a somite

A

Ball of mesoderm

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6
Q

WHat do somites begin as and where do they appear

A

First known as somitomeres

Appear in the cephalic region of embryo then develop cephalo-caudally

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7
Q

How many somites should be present at the end of 5th week

A

42-44 paris

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8
Q

Which somites disappears

A

first occipital somite

last 5-7 coccygeal somite

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9
Q

What somites are left and what do they do

A 
3 occipital
8 cervical
12 thoracic
5lumbar
5 sacral
3-5 coccygeal

Go on to form axial skelton

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10
Q

How does the sclerotome form

A

Somites (contain fibroblasts-like cells)
They then arrange themselves in a donut shape around a small lumen and become epithelial cells
Cells in the ventromedial wall of somite lose epithelial characteristics
Change their position to surround the neural tube and notochord
forming the sclerotome

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11
Q

What does scelerotome eventually form

A

Vertebrae and ribs

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12
Q

How does the myotome form

A

Cells in the dorsomedial and ventrolateral walls of somite form the myotome

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13
Q

What is the myotome

A

Precursor for muscle cells

Some muscle precursors cells migrate into the parietal later of lateral plate mesoderm to form body wall muscles

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14
Q

How does the dermatome form

A

Cells in between the muscle precursor cells fo the somite form the dermatome

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15
Q

What is the dermomyotome

A

Myotome cells migrate beneath the dermatome to form a dermomyotome

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16
Q

How is the dermis layer of the back formed

A

Dermatome cells become migratory and migrate beneath the surface ectoderm, forming the dermis of the back

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17
Q

How is the dermis layer of the back formed

A

Dermatome cells become migratory and migrate beneath the surface ectoderm, forming the dermis of the back

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18
Q

How are the myotome and dermatome innervated

A

Retains innervation from its segment of origin

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19
Q

What does the intermediate mesoderm form

A

Forms urogenital structures
Forms future nephortomes
More caudally forms the nephrogenic cord

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20
Q

What does the lateral plate mesoderm go on to form

A

Lines the intraembryonic cavity
Lines the organs and gut tube
Goes on to form the serous membranes of future peritoneal, plural and pericardial cavities

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21
Q

What does parietal LPM form

A

lateral body wall folds
form the dermis of skin in body wall and limbs
Form muscles of limbs, body wall and costal cartilages along with sclerotome and muscles cells from somites

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22
Q

What does the visceral LPM form

A

With the endoderm forms the wall fo the gut tube

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23
Q

What does the intraembryonic cavity form

A

Thoracic and abdominopelvic cavities

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24
Q

What does the paraxial mesoderm from regarding head and neck

A

Somiters and somitomeres
LArge portion of membranous and cartilaginous parts of skull
All voluntary muscles of craniofacial region
Dermis
Connective tissue of dorsal head
Meninges caudal to prosencephalon

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25
What does the LPM do regarding head and neck
Laryngeal cartilages | Connective tissue of laryngeal region
26
How do thickened regions of ectoderm assist in development of head and neck
With NCC, form neurons of the 5th, 7th, 9th and 10th cranial sensory ganglia
27
What do pharyngeal arches contain
Consists of a core of mesenchymal tissue derived from mesoderm Covered externally by ectoderm COnvered internally by endorderm
28
What components do each pharyngeal arch have
Muscular component SKeletal/cartilaginous component cranial nerve arterial component
29
Which cranial nerves contribute to the pharygeal arches
CN V CN VII CN IX CN V
30
What happens at the end of 4th week of development regarding face development
Centre of face is formed by the stomedeum closed by the oropharyngeal membrane surrounded by the first pair of pharyngeal arches
31
What two parts is the first pharyngeal arch made up of
Maxaially part - latyeral to stomedeum | Mandibular part - caudal to stomodeum
32
What is the stomodeum
Future oral cavity
33
What dies maxiallary process of 1st pharyngeal arch go on to form
Future maxilla, zygomatic bone and part of the temporal bone
34
What dies mandibulary process of 1st pharyngeal arch go on to form
Contains Mercel's cartilage | Mesenchyme surround Meckel's cartilage will become future mandible
35
What muscles are associated with the 1st PA
muscles of mastication | Anterior belly of digastric, mylohyoid, tensor tympani, tensor palatini
36
What nerve components are associated with the 1st PA
The mandibular branch of CN V supplies all the muscles | All 3 branches of CN V provide innervation to the skin of the face
37
What catilagionous component dfoes the 2nd PA contain
Reichert's cartilage
38
What does reichert's cartilage go on ot form
Stapes Styloid process of temporal bone Stylohyoid ligament Parts of the hyoid bone
39
Muslces involved with 2nd PA
Stapedius, stylohyoid, posterior belly of digastric, auricular muscles, and muscle fo facial expression
40
What nerve is involved with 2nd PA
CN VII
41
The CArtilage of 3rd PA function
Produces parts of the hyoid bone
42
The mesenchyme of which PA forms most of the external ear
2nd PA
43
MSucles associated with the 3rd PA
Styloharyngeus muslce
44
NErve ivolved with 3rd PA
CN IX
45
Cartilagious componentn of 4th and 6th PA function
Fuse to form laryngeal cartialges which form the thyroid, cricoid, arytenoid, corniculate and cuneiform
46
Muslces of 4th PA
Cricothyroid, lavator veli palatini, constrictors of the pharynx
47
Muslces of 6th arch
Intrinsic muscles of larynx
48
Nerve fo 4th PA
Superior laryngeal rbanch of CN X
49
nerve of 6th PA
Recurrent laryngeal branch of CN X
50
Which PA contributes to the bones of middle ear, part of the external ear and the EAM
1st arch
51
What is the aortic sac
Distal part of the truncus arteriosus
52
What happens to the first AA
mostly regresses, with small portion forming the maxilalry artery
53
What happens to he 2nd aortic arch
Disappers
54
What happens to the 3rd aortic arch
Forms common carotid artery and the proximal part of the ICA | Gives rise to the ECA
55
What happens to te 4th aortic arch
Left side forms part of the aortic arch between the left common carotid and left subclavian Right forms the right subclavian artery
56
What happens to the 6th aortic arch
Pulmonary arch Proximal part of the right pulmonary artery Let side it forms the ductus arteriosus and left pulmonary artery
57
What happens to the right forsal aorta and the connection between 3rd and 4h arch
Regresses
58
What happens to the right dorsal aorta and the connection between 3rd and 4h arch
Regresses
59
What does Pharyngeal pouch 1 form
Distal end forms tympanic cavity | Proximal end forms auditory tube
60
What does Pharyngeal pouch 2 form
Palatine tonsil and the tonsilar fossa
61
What does Pharyngeal pouch 3 form
Inferior parathyroid glands | Thymus
62
How does thymus migrate
Both inferior parathyroid gland and thymus lose their connection to wall of the pharynx Thymus migrates towards mediastinum, pulling the inferior parathyroid gland with it Thymus fuses with its counterpart from the other side
63
What does Pharyngeal pouch 4 form
Superior parathyroid glands
64
What is the ultimopharyngeal body
Becomes embedded in the thyroid gland as parafollicular cells These cells secrete calcitonin
65
How does tongue form
Initially from 3 swellings Two lateral lingual swellings One medial selling Both originate from the 1st pharyngeal arch Another swelling then forms called the copula Epiglottis then forms from the another swelling from the 4th arch
66
From where does the copula form
Swelling formed from the mesoderm of the 2nd, 3rd and 4th arches
67
What is immediately behind the epiglottis swelling
Laryngeal orifice
68
What forms the anterior 2/3 of the tongue
Lateral lingual swelling and medial swelling increase in size and merge
69
What performs the general sensory innervation of the anterior part of the tongue
CN V3
70
What si the posteiror part of tongue derived from
Arches 2-4
71
What provides sensory innervation of the posteror aprt of tonue
CN IX
72
How does the thyroid gland develop
Develops from the epithelial proliferation situated at a point called the foramen caecum Develops as a diverticulum Descends anterior to the pharynx Connected via the thyroglossal duct to the tongue (should regress) Reaches final position ventral to the trachea
73
What does the face form from
Facial prominences which are derived from the first PA
74
What are the facial prominences
Maxillary prominence - lateral to stomodeum Mandibular prominence - caudal to stomodeum Frontonasal prominence - upper border of stomodeum Bilateral thickening of surface ectoderm appear - nasal placodes
75
How do nasal pits form
Invagination of nasal placodes
76
What happens after week 5 regarding the maxillary prominence
Increase in size and grow medially compress the medial nasal prominences towards midline, which fuse Gap between medial nasal prominence and maxillary prominence is lost forming upper lip
77
How is upper lip formed
Fusion of the maxillary and medial nasal prominence
78
How does lower lip and mandible form
Mandibular prominence grows towards one another and fuse in the midline
79
How does intermaxillary segment form
Two nasal prominences merge together
80
What is the main part of the palate formed from
maxillary prominence
81
What acts as the landmark between the primary and secondary palates
Incisive foramen
82
What are anterior cleft deformities
lateral cleft lip Cleft upper jaw Cleft between the primary and secondary palate These are due to partial or complete failure of the fusion of the maxillary and medial nasal prominence
83
What are posterior cleft deformities
Cleft palate - palatine shelves do not fuse | Cleft uvula
84
What are palatine shelves
a medially directed outgrowth of the embryonic maxilla; when fused with its opposite number it forms the secondary palate
85
What does the labial component form
Philtrum of the upper lip
86
What does the upper jaw component form
4 incisor teeth
87
What does the Palatal component form
Primary palate
88
What are the pharyngeal clefts lined with
ectoderm
89
What was previously thought to form the EAM and what actually forms it
Previosly thoguth to be formed by the 1st pharyngeal cleft | Actually arised from the 1st PA
90
What causes PC 1 to disappear
PA2 expands in size | Also extends caudally overlapping cleft 2 and 3
91
How do cleft 2,3 and 4 lose contact with outside | What happens to them after
PA 2 meets another bulk of tissue called epicardial ridge and they merge cleft 2,3 and 4 form a cavity called the cervical sinus that will disappear
92
What is branchial fistula
Remnants of the 2nd, 3rd and 4th pharyngeal clefts | Cysts can be remains of the cervical sinus that should regress

Anatomy YR1 (29 decks)

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