Lecture 7 Head and Neck Embryology

Question 1

What does the neck develop from

Answer 1

Branchial/Pharyngeal arches

Question 2

Where does the face develop from

Answer 2

5 mesenchymal processes/prominences

Question 3

Where does the skull develop from

Answer 3

The mesenchyme in the head region of developing embryo

Question 4

What 2 areas are there no mesoderm

Answer 4

Sites of future mouth and anus- ectoderm stuck directly to endoderm

Question 5

What does notochord formation lead to

Answer 5

Axis formation in embryo- embryo has left and right

Question 6

The neural creat mixes with mesoderm to form

Answer 6

Mesenchyme

Question 7

What arises from neural crests cells

Answer 7

Melanocytes, craniofacial cartilage and bone, smooth muscle, peripheral and enteric neutrons and glia

Question 8

What are somites

Answer 8

Derived from the paraxial mesoderm and form structures like the axial skeleton and muscles

Question 9

How many somites develop in human embry

Answer 9

33

Question 10

Wha are the major and minor somite components

Answer 10

Sclerotome- vertebrae, ribs and cartilage
Myotome-muscle
Dermatome- dermis on back
Syndetome-tendons

Question 11

What are the pharyngeal/branchial arches

Answer 11

Series of arches which develop around the future mouth and pharynx

Question 12

How many branchial arches develop in humans

Answer 12

5, 6 arches develop by arch number 5 disappears

Question 13

What embryological tissues make up the branchial arches

Answer 13

Ectoderm- lines outside
mesoderm- cartilage and muscles
endoderm- pouches between arches and lines inside

Question 14

What nerve does the 1st arch form

Answer 14

Mandibular branch of trigeminal V3

Question 15

What nerve does the 2nd arch form

Answer 15

Facial nerve (CN VII)

Question 16

What nerve does the 3rd arch form

Answer 16

Glossopharyngeal (CN IX)

Question 17

What nerve does the 4th arch form

Answer 17

Superior laryngeal branch f vagus (CNX)

Question 18

What nerve does the 6th arch form

Answer 18

Recurrent laryngeal branch of the vagus (CN X)

Question 19

All facial muscles are innervated by CN VII. What does that mean

Answer 19

All facial muscles developed from 2nd pharyngeal branch

Question 20

What is the innervation of the digastric muscle

Answer 20

• Anterior belly innervated by mandibular division of trigeminal nerve (V3)-1st pharyngeal arch
• Posterior belly innervated by facial nerve- 2nd pharyngeal arch

Question 21

What branch does the mylohyoid originate from

Answer 21

1st branch- V3

Question 22

What branch does the stylohyoid originate from

Answer 22

2nd branch- facial

Question 23

Your 4th and 6th arch form which structures

Answer 23

Larynx
Thyroid cartilage
Cricoid cartilage

Question 24

Your 1st arch forms what structure

Answer 24

Mandible

Question 25

Your 2nd arch forms what structure

Answer 25

Hyoid bone to styloid process

Question 26

What other structures develop from the branchial arches

Answer 26

* Tongue * Thyroid gland * Parathyroid gland * Part of the pituitary gland

Question 27

Arch 1 forms what part of the tongue

Answer 27

Anterior 2/3rds- oral

Question 28

Arch 2 forms what part of the tongue

Answer 28

Initial contribution to surface lost

Question 29

Arch 3 forms what part of the tongue

Answer 29

Posterior 1/3- pharyngeal

Question 30

Arch 4 forms what part of the tongue

Answer 30

Epiglottis and adjacent regions

Question 31

Name the 5 processes the face develops from

Answer 31

Frontonasal process Medial process Two maxillary processes Two mandibular processes

Question 32

The nasal placed invaginated to form what

Answer 32

Nasal pit--> Nostril

Question 33

The medial process grows down to form th

Answer 33

Philtrum

Question 34

The 2 maxillary processes originate from

Answer 34

maxillary part of 1st branchial arch mesoderm

Question 35

The 2 mandibular processes originate from

Answer 35

1st arch mesoderm that fuse

Question 36

Describe the stages of development for the palate

Answer 36

Medial nasal process grows downwards and forms philtre- primary palate From maxillary process 2 palatine shelves grow inwards This separates the oral and nasal cavity

Question 37

When does cleft palate occur

Answer 37

When palatine shelves formed from the maxillary processes fail to meet in the midline to make the secondary palate

Question 38

how are cranial vault- left bones formed by

Answer 38

Intramembranous ossification Calcaria

Question 39

How are irregular bones from base of skull formed

Answer 39

Endochondral ossification

Question 40

What are Viscercranium

Answer 40

Capsules formed around sensory organs

Question 41

What is Craniosynostosis

Answer 41

Is a condition in which one or more of the sutures close too early, causing problems with normal brain and skull growth. Premature closure of the sutures may also cause the pressure inside of the head to increase and the skull or facial bones to change from a normal, symmetrical appearance.

Question 42

(Base of skull) Where is mesenchyme around the notochord derived from

Answer 42

Predominantly neural crest cells that preform in cartilage first and later ossify

Question 43

Where are sensory capsules derived from

Answer 43

Mesoderm of somites in head and neck region. These preform in cartilage and ossify to form bones around the sense organs, nose, eyes and ears