Pharyngeal Arches

Question 1

Pharyngeal Apparatus consists of…

Answer 1

Pharyngeal Arches
Pharyngeal Pouches
Pharyngeal Grooves/Clefts
Pharyngeal Membrane

Question 2

How do pharyngeal arches begin to form?

Answer 2

o Begin to develop early in the fourth week as neural crest cells migrate into the head and neck region

Question 3

Where do Neural crest cells come from and what direction do they travel?

Answer 3

NCC come from the developing neural plate

They migrate posterior/dorsal neural tube region to anterior ventral

Question 4

Major events on day 24 due to rapid proliferating mesenchyme

Answer 4

Stomodaeum forms laying ectoderm throughout oral cavity (most oral cavity forms from this)
Stomodaeum and parynx are seperated by the buccopharyngeal membrane
Buccopharyngeal membrane ruptures to open the oropharynx

Question 5

Each arch contains

Answer 5

Nerve, artery, cartilage, muscles

Question 6

Arch I Artery

Answer 6

Terminal branch of maxillary artery

Question 7

Arch I Skeletal

Answer 7

Derived from arch cartilages (from NCC):
Max cart –> Incus
Meckels cart –> Melleus
Derived by direct ossification from arch dermal mesenchyme
maxilla, zygomatic, squamos protion of temporal, mandible

Question 8

Arch I Muscles

Answer 8

Muscles of mastication
Mylohyoid
Anterior belly of digastric
Tensor Tympani

Question 9

Arch I Nerves

Answer 9

Trigeminal nerve V (5)

-Max and Mand division

Question 10

Arch II Artery

Answer 10

Stapedial artery (embryonic)—> Corticotympanic artery (adult)

Question 11

Arch II Skeletal

Answer 11

Stapes
Styloid process
Part of Hyoid

Question 12

Arch II Muscle

Answer 12

Facial expression
Posterior belly of digastric
Stylohyoid
Stapedius

Question 13

Arch II Nerve

Answer 13

Facial Nerve VII (7)

Question 14

Arch III Artery

Answer 14

Common carotid artery

root of internal carotid

Question 15

Arch III Skeletal

Answer 15

Part of Hyoid

Question 16

Arch III Muscle

Answer 16

Stylopharyngeus

Question 17

Arch III Nerve

Answer 17

Glossopharyngeal IX (9)

Question 18

Arch IV Artery

Answer 18

Arch of aorta

Right Subclavian artery

Question 19

Arch IV Skeletal

Answer 19

Thyroid

Question 20

Arch IV Muscles

Answer 20

Constrictors of pharynx

Question 21

Arch IV Nerve

Answer 21

Vagus X

-Superior laryngeal branch

Question 22

Arch VI Artery

Answer 22

Ductus Arteriosus

Pulmonary arteries

Question 23

Arch VI Skeletal

Answer 23

Circoid

Question 24

Arch VI Muscles

Answer 24

Intrinsic muscles of larynx

Question 25

Arch VI Nerve

Answer 25

Vagus Nerve X | Recurrent laryngeal branch

Question 26

Derivatives Of Pharyngeal Clefts/ Grooves

Answer 26

Cleft I: External Auditory Meatus Paryngeal Arch II: Mesenchyme rapidly proliferate and cover remaining clefts Clefts 2-4: Cervical Sinus

Question 27

Cervical Cysts | -Cause, characteristics

Answer 27

Failure of resorption during cervical sinus formation Forms at LATERAL border of neck, anterior to sternocleidomastoid Can be isolated or fistulated, may be infected or purulent (pus)

Question 28

Formation of Pharyngeal Pouches

Answer 28

Internal endoderm forms outline of oropharynx | Pharyngeal pouches form around oropharynx, and eventually form pharyngeal derivatives

Question 29

Pouch I

Answer 29

Pharyngotympanic tube

Question 30

Pouch II

Answer 30

Palatine tonsil

Question 31

Pouch III

Answer 31

Inferior Parathyroid and thymus

Question 32

Pouch IV

Answer 32

Superior Parathyroid and Ultimo Branchial Body

Question 33

Ultimo Branchial Body

Answer 33

Joins thyroid and forms Follicular C cells which produce Calcitonin

Question 34

Thyroid Primordium Migration

Answer 34

Forms at midline of pharynx below tuberculum impar 2 lobes migrate from foramen cecum --> below cricoid Forms thyroglossal duct during migration

Question 35

Thyroglossal Duct Cysts Location

Answer 35

Found at the MIDLINE of the neck Form by improper degeneration of thyroglossal duct Confined or fistulated through the oral duct Can be infected, purulent, obstruct airway

Question 36

Development of Tongue | Oral Part

Answer 36

Fusion of: Lateral lingual swellings Madian tonhue bud (Tuberculum par)

Question 37

Development of Tongue | Paryngeal Part

Answer 37

Fusion of Copula (hypobranchial eminence) | formed from arches 2, 3, 4 --> fuse to form terminal sulcus

Question 38

Tongue Muscles

Answer 38

Arise from Occipital Somites which migrate into tongue area

Question 39

Pharyngeal Arch Defects

Answer 39

Facial Clefting Micrognathia (small mouth) Hemifacial Microstomia (Lower half of face underdeveloped)