Week 1 - D - Embryology 1 - Pharyngeal arches and ear

Question 1

What embryological structures contribute to the development of the face and neck?

Answer 1

The pharyngeal arches

Question 2

What weeks do the pharyngeal arches develop in? Try be more specific for each arch if possible

Answer 2

Devlop in weks 4 and 5 of embryology Arch 1 - develops at 22 days Arch 2 and 3 - develops at day 24 Arch 4 and 6 - develops at day 29

Question 3

Which arch does not result in any human structure?

Answer 3

Pharyngeal arch 5

Question 4

Each pharyngeal arch consists of an artery from the aortic arch, a cranial nerve component, a neural cells crest and lossely organized mesodermic tissue (mesenchyme) What from the pharyngeal arches gives rise to the musculature of the face and neck?

Answer 4

The mesoderm

Question 5

What does the nerual crest cells of the pharyngeal arches give rise to?

Answer 5

The neural crest cells give rise to the skeletal component of the face

Question 6

What 4 things does the pharyngeal arches consist of then?

Answer 6

Pharyngeal arches consist of Core of mesenchyme derived from mesoderm - gives rise to musculature of face and neck Neural crest cells - gives rise to skeletal components of face Cranial nerve component Artery

Question 7

The pharyngeal arches have clefts and pouches externally and internally respectively Which are the derivatives for the arches, pouches and cleft? (ie the germ layers)

Answer 7

CAP Clefts - ectoderm Arches - mesoderm Pouches - endoderm

Question 8

The pharyngeal arches are Externally separated by deep pharyngeal clefts - ectoderm lining What separates the pharyngeal arches internally?

Answer 8

The pharyngeal pouches - endoderm lining

Question 9

What is the cranial nerve component of pharyngeal arch 1?

Answer 9

Trigemenial nerve - maxillary and mandibular divisions

Question 10

Which cranial nerves are components of pharyngeal arches 2 and 3?

Answer 10

Arch 2 - cranial nerve 7 - facial nerve Arch 3 - cranial nerve 9 - glossopharyngeal nerve

Question 11

What are the two nerves that supply pharyngeal arches 4 and 6?

Answer 11

Arch 4 - superior laryngeal nerve branch (branch of vagus nerve) Arch 6 - recurrent laryngeal branch (brannch of vagus nerve)

Question 12

Reminder What gives rise to the skeletal components of the face? What are the two portions of the first arch? (state the trigeminal nerve supply)

Answer 12

The neural crest cells The first arch has a dorsal portion - maxillary supply and a Ventral potrion - mandibular supply

Question 13

What part of the first arch gives rise to meckel’s cartilage? What does meckel’s cartilage give rise?

Answer 13

The ventral portion (mandibular supply) gives rise to meckel’s cartilage Meckel’s cartilage gives rise to the cartilaginous arch of the mandibular and the incus and malleus

Question 14

What muscle of the middle ear does the 1st pharyngeal arch give rise to? What muscles of the face does it give rise to?

Answer 14

Gives rise to the tensor tympani muscle which attaches to the handle of the malleus Gives rise to the muscles of mastication

Question 15

What skeletal structures does the 2nd pharyngeal arch give rise to? ( 2 bones and a ligament)

Answer 15

Stapes, styloid process of temporal bone and stylohyoid ligament Also gives rise to the upper part of the hyoid bone

Question 16

Name 3 muscles that come from the 2nd pharyngeal arch? What is the cranial nerve supply?

Answer 16

Muscles of facial expression Stapedius Stylohyoid The facial nerve

Question 17

What pharyngeal arch gives rise to the lesser arch of the hyoid bone? What is the cranial nerve?

Answer 17

Pharyngeal arch 3 Glossopharyngeal nerve

Question 18

What cartilages are supplied by arches 4 and 6?

Answer 18

The laryngeal cartilages - thyroid, cricoid

Question 19

Which pharyngeal arch has the muscle that opens the vocal cords to reveal the rima glottidis? Which intrinsic laryngeal muscle does this pharngeal arch not make? what pharyngeal arch makes this muscle?

Answer 19

Pharyngeal arch 6 contributes to the posterior cricoarytenid muscle which causes abduction of the vocal cords Arch 6 contributes to all the intrinsic laryngeal muscle except The cricothyroid muscle which pharyngeal arch 4 contributes to

Question 20

What derivative gives rise to the pahryngeal celfts? What does pharyngeal cleft 1 give rise to?

Answer 20

Clefts - ectoderm Cleft 1 gives rise to the external acoustic meatus

Question 21

What derivative gives rise to the pharyngeal pouches? Which pharyngeal pouch gives rise to the palatine tonsil?

Answer 21

Pouches - endoderm The 2nd pharyngeal pouch

Question 22

What three things does the pharyngeal pouch 1 give rise to?

Answer 22

The middle ear The eustachian tube The tympanic membrane

Question 23

Where do T cells originate and where do they mature? WHat pharyngeal pouch gives rise to the place where they mature?

Answer 23

They originate in the bone marrow and mature in the thymus Pharyngeal pouch 1 gives rise to the thymus as well as the inferior parathyroid glands

Question 24

What structure gives rise to the parafollicular cells (aka C-cells or calcitonin producing cells)? Which pharyngeal pouch gives rise to this structure?

Answer 24

Ultimopharyngeal body (ultimobranhcial) Pharyngeal pouch 2 gives rise to this

Question 25

Otic vesicles give rise to the inner ear What formed by the thickening if the ectoderm gives rise to the structure that gives rise to the otic vesicles?

Answer 25

The otic placodes The invaginating otic placodes become an otic pit which becomes the otic vesicle

Question 26

What portion of the otic vesicle gives rise to the semicircular canals and what portion gives rise to the cochlea?

Answer 26

Utricular portion of otic vesicle gives rise to semicircular canals Saccular portion of otic vesicle gives rise to the cochlea

Question 27

What are the dilated ends of the semilircular canal known as?

Answer 27

(crus) ampulla

Question 28

What is found in the ampulla that is the sensory organ of rotation and contains the sensory cells for balance?

Answer 28

The crista ampullaris has the Vestibular fibres of VIII

Question 29

The saccule gives rise to the cochlea and connects to it via the what? What is the organ of hearing contained in the cochlear duct known as?

Answer 29

The ducts reuniens Known as the organ of corti

Question 30

What sepearaes the cochlear duct from the scala vestibuli and the scala tympani?

Answer 30

Vestibular mebrane (Reissner’s mermbrane) separates the cochlear duct from the scala vestibuli Basilar mebrane separates the cochlear duct from the scala tympani The organ of corti is found in the basilar membrane

Question 31

What ligament holds the cohclear duct in place?

Answer 31

The spiral ligament The auditory nerve fibres insert at the organ of corti When the little hair cells are moved due to the movement of fluid because of sound waves, this creates a nerve impulse that travels along the cochlea

Question 32

6 mesenchymal proliferations surrounding the 1st pharyngeal cleft give rise to hillocks Where do the proliferations come from? WHat do hillocks form?

Answer 32

3 from arch 1 3 from arch 2 Hillocks fuse to form the auricle of the ear

Question 33

What syndrome is this? Microtia with hemifacial microsomia (Hemifacial Microsomia is a condition in which the lower half of one side of the face is underdeveloped and does not grow normally.) (Microtia is a congenital deformity where the pinna (external ear) is underdeveloped)

Answer 33

This child has Goldenhar syndrome

Question 34

What condition is it where both sides of the face are affected? it is similar to goldenhar syndrome Due to a chromosme 5 abnormality

Answer 34

Treacher-Collin syndrome