Week 3 - Embryology of the Head and Neck

Question 1

Carnegie stage 4 Embryo visualised

Answer 1

Question 2

Carnegie stage 23 Embryo visualised

Answer 2

Question 3

What does lateral folding do?

Answer 3

Helps bring the gut tube back inside the body

Question 4

What do Foregut derivatives extend from?

Answer 4

Head to Abdomen

Question 4

Derivatives of the Foregut

Answer 4

Question 5

What structures are related to connecting the outside to the inside? i didnt know how to word it properly innit

Answer 5

• Ectoderm and Endoderm only (seen in Oral and Rectal areas)
• Oropharyngeal membrane & cloacal membrane
• These are points of transition

Question 6

What part of this becomes the head and neck?

Answer 6

The lumps and bumps

Question 7

What is a Pharyngeal arch?

Answer 7

= Bump with extoderm, mesoderm, endoderm

Question 8

What is a Pharyngeal crest/fold?

Answer 8

= invaginations of the ectoderm

On diagram -> blue corners into the structure

Question 9

What are Pharyngeal pouches?

Answer 9

= evaginations of endoderm

On diagram -> yellow corners into structure from inside

Question 10

What are Pharyngeal Arch Arteries?

Answer 10

= Aortic Arch arteries arising in the region of the pharyngeal apparatus

Question 11

What do Neural Crest cells give rise to?

Answer 11

Skeletal components

Question 12

What does Mesoderm give rise to?

Answer 12

Muscular components

Question 13

What do Aortic Arch Arteries give rise to?

Answer 13

Vascular supply to each of the arches

Question 14

What does Endodermal layer give rise to?

Answer 14

Pharyngeal pouch components

Question 15

Do Pharyngeal Arch Cranial Nerves & Arteries elongate and grow into or out of the Pharyngeal apparatus?

Answer 15

Grow INTO the area

Question 16

What Cranial nerves does the Brainstem give rise to related to the Pharyngeal arch?

Answer 16

Cranial Nerves 5, 7, 9 & 10 -> these are the only ones related to the Pharyngeal Arch -> They grow into a bump of the pharyngeal apparatus

Question 17

What nerves grow into each bump of the Pharyngeal Arch

Answer 17

Arch 1 -> Trigeminal nerve
Arch 2 -> Facial nerve
Arch 3 -> Glossopharyngeal nerve
Arch 4 -> Superior Laryngeal nerve
Arch 6 -> Recurrent Laryngeal nerve

Question 18

Is there any crossing of the Cranial Nerves?

Answer 18

Yes -> they are in close proximity to each other during development and may cross

Question 19

Arteries of the Pharyngeal Arch and bumps

Answer 19

Question 20

What are the skeletal features involved with each bump of the Pharyngeal Arch?

Answer 20

Arch 1 -> Skeletal features of mastication (Upper inner ear bones & Maxially process below the eye)
Arch 2 -> Lower part of the inner ear to upper part of hyoid bone
Arch 3 -> Lower part of hyoid bone
Arch 4 & 6 -> Thyroid & Pharynx
Arch 5 disappears

Question 21

Pharyngeal Arch summarised

Answer 21

Question 22

What are the Arch 1 Cartilage and Bony Derivatives that help with mastication?

Answer 22

Maxillary process:
- Mesenchyme (from neural crest) -> premaxilla, maxilla, zygomatic bone and part of temporal bone
Mandibular process:
- Meckels cartilage -> Incus and Malleus
- Mandible

Question 23

What are the divisions of the Trigeminal nerve that supplies Arch 1

Answer 23

CNV = Cranial nerve 5

• CNV1 = Ophthalamic
• CNV2 = Maxillary
• CNV3 = Mandibular

Question 24

What type of information is conveyed via each division of the Trigeminal nerve?

Answer 24

Ophthalmic -> General sensory Maxillary -> General sensroy Mandibular -> General motor and sensory

Question 25

What are special sensations?

Answer 25

- ability to see, taste etc - only found in the head and neck

Question 26

What are the muscles derived from Arch 1 linked to mastication? and what are they innervated by?

Answer 26

- Temporalis - Part of the Lateral Pterygoid - Masseter Innervated by the branches of the Mandibular division of Trigeminal nerve

Question 27

What arches does the ear derive from?

Answer 27

Between Arches 1 & 2

Question 28

What is the tissue origin for External Acoustic Meatus (1st Groove/Cleft Derivative) and Tympanic Recess (1st Pouch Derivative)?

Answer 28

External Acoustic Meatus -> Ectoderm Tympanic Recess -> Endoderm

Question 29

Derivatives of Ear summarised$

Answer 29

Question 30

What is Arch 2 associated with?

Answer 30

Facial expressions

Question 30

Does Arch 1 or 2 develop first? What is the significance of this?

Answer 30

Arch 1 develops first Significance: - muscles for facial expression will be superficial to muscles of mastication because they develop after

Question 31

What is the relationship between the Lingual nerve and Chorda Tympani nerve?

Answer 31

- Chorda Tympani nerve connects to Lingual nerve on its way to the tongue - Lingual is Arch 1 whule Chorda Tympani is Arch 2

Question 31

What are some functional components of the facial nerve?

Answer 31

Visceral motor Sensory Muscle motor Taste

Question 32

What Arch does the oral cavity derive from?

Answer 32

Between Arches 2 and 3

Question 33

What is the adult derivative of pouch 2?

Answer 33

Tonsillar fossa

Question 34

What is the Arch 3 skeletal derivative?

Answer 34

Greater horn of the Hyoid Bone

Question 35

What is the Arch 3 muscular derivative?

Answer 35

Stylopharyngeus muscle (name literally means between Arch 2 and Arch 4/6)

Question 36

What is the Arch 3 nerve derivative? What type of innervation?

Answer 36

Glossopharyngeal Nerve (CN IX) Innervation: - General sensory - Special sensation - Somatic motor

Question 37

What is the Pharyngeal Plexus?

Answer 37

mixing of nerves around the pharynx

Question 38

Where do some pouches migrate to?

Answer 38

inferiorly to the Thorax

Question 39

What does Pouch 3 develop into?

Answer 39

Inferior parathyroid gland and Thymus

Question 40

What does Pouch 4 develop into?

Answer 40

Superior parathyroid gland

Question 41

What are Arch 4 and 6 Cartilage and Bony derivatives?

Answer 41

Cricoid Cartilage and Arytenoid Cartilage

Question 42

What are Arch 4 and 6 muscle derivatives?

Answer 42

Cricothyroid Levator veli palatine Pharyngeal Constrictors (superior, middle, and inferior) Stylopharyngeus Larynx

Question 43

What nerve is derived from Arch 4 & 6

Answer 43

Vagus nerve

Question 44

What is Pouch 4 associated with?

Answer 44

Thyroid

Question 45

Sensory Innervation Territories

Answer 45