10-C Cranial Primordia and Nerves

Question 1

Name the 3 main types of primordial tissue in the head and neck that pair with cranial nerves?

Answer 1

placodes, somites and pharyngeal/branchial arches

Question 2

What is a placode?

Answer 2

ectodermal thickenings that form structures for our special senses

Question 3

Name the 3 placodes in the head.

Answer 3

olfactory, lens and otic placodes

Question 4

What tissues form from the olfactory and otic placode?

Answer 4

form neurons of the olfactory (most sensory oriented olfactory cells) and vestibulocochlear nerves respectively (membranous labyrinth and sensory neurons of cranial nerve VIII)

Question 5

What does the lens placed form?

Answer 5

lens of the eye (not any of the receptive parts of the eye)

Question 6

What are the somites role in the head? What do the respective somites become?

Answer 6

masses of mesoderm that form skeletal muscles: preotic (muscles of the eye) and post otic (muscles of the tongue)

Question 7

What structures develop from cranial neural crest cells?

Answer 7

form cell bodies in sensory ganglia associated with cranial nerves and four parasympathetic ganglia in the head; migrate into the pharyngeal arches and form skeletal elements like the mandible and middle ear ossicles; form smooth muscle cells that contribute to connective tissue capsules of the thymus, parathyroid and thyroid glands

Question 8

What is a branchial arch?

Answer 8

mass of tissue that flank the developing gut (aka pharyngeal arches)

Question 9

What is derived from a branchial arch?

Answer 9

bone or cartilage, skeletal muscle, skin from the overlying ectoderm, and area of the gut from the lining endoderm

Question 10

Each branchial arch (during intermediate development) contains what 3 elements?

Answer 10

artery, cartilaginous (or bone) bar, a particular nerve and muscles which are innervated by the nerve

Question 11

The first arch develops into which skeletal elements?

Answer 11

the upper and lower jaws as well as the first 2 ossicles

Question 12

What do II- VI arches form?

Answer 12

II (stapes, styloid process, stylohyoid ligament) III (hyoid bone) IV (thyroid cartilage) and VI (cricoid cartilage)

Question 13

Which two arches form the muscles of mastication and facial muscles respectively?

Answer 13

1st and 2nd arches

Question 14

Endoderm/Ectoderm lining each branchial arch is innervated by the nerve of _____ (which arch?)

Answer 14

the nerve of that particular arch

Question 15

What is the different location of the brachial cleft vs. brachial pouch?

Answer 15

clefts are locate on the exterior side of arches while pouches are located on the interior side of arches

Question 16

Name the structure that forms where the 1st brachial cleft meets the first brachial pouch.

Answer 16

tympanic membrane

Question 17

What is the derivative of the 1st pharyngeal pouch?

Answer 17

middle ear and eustation tube

Question 18

What is the derivative of the 2nd pharyngeal pouch?

Answer 18

fossa for palatine tonsil

Question 19

What is the derivative of the 3rd pharyngeal pouch?

Answer 19

inferior parathyroid gland and thymus

Question 20

What is the derivative of the 4th pharyngeal pouch?

Answer 20

superior parathyroid gland

Question 21

What is the derivative of the 5th pharyngeal pouch?

Answer 21

ultimobranchial body (c or calcitonin cells of the thyroid)

Question 22

What is the derivative of the 1st pharyngeal cleft?

Answer 22

external auditory meatus

Question 23

Which cranial nerves go to placodes?

Answer 23

1,2,8

Question 24

Which cranial nerves go to somites?

Answer 24

pre-otic: 3, 4, 6 post otic: 7, also 12

Question 25

Which cranial nerves go to branchial arches

Answer 25

arch 1 (5), arch 2 (7) arch 3 (9) arch 4 and arch 6 (10) *11 also

Question 26

Name the possible sensory nerve components of cranial nerves.

Answer 26

special somatosensory, general somatosensory, general viscerosensory, and special viscerosensory

Question 27

Name the possible motor nerve components of the cranial arches.

Answer 27

somatomotor, visceromotor, branchiomotor (innervates skeletal muscles from branchial arches)

Question 28

Name the cranial nerves that contain only sensory fibers.

Answer 28

1, 2, 8

Question 29

Name the cranial nerves that contain only motor fibers.

Answer 29

3, 4, 6, 12

Question 30

Name cranial nerves that contain a combination of sensory or motor fibers.

Answer 30

5, 7, 9, 10, 11

Question 31

Name cranial nerves that carry parasympathetic.

Answer 31

3,7,9 (and 10) parasympathetic ganglia include: ciliary, pterygopalatine, otic and submandibular

Question 32

______ _________ cell bodies for the head and neck are not components of cranial nerves.

Answer 32

sympathetic preganglioinic

Question 33

Name the 3 subdivisions of the trigeminal nerve.

Answer 33

opthalmic nerve, maxillary nerve and mandibular nerve (which poke through the supraorbital, infraorbital and mental foramen)

Question 34

Muscles of facial expresser insert into _____

Answer 34

skin, to protect and produce facial expressions