Development of the Head and Neck

Question 1

What are the pharyngeal/brachial arches?

Answer 1

Outpouchings of mesoderm on both sides of developing pharynx

Precursors for = muscles, cartilage, vessels

First seen during 4 week of devel

Question 2

What structures constitute the building blocks for the head and neck region?

Answer 2

Pharyngeal arches

Frontonasal prominence

Question 3

What does each pharyngeal arch have associated with it?

Answer 3

Artery

Nerve

Cartilage bar

Question 4

Which cranial Ns are associated with the pharyngeal arches?

Answer 4

5, 7, 9, 10

Mixed motor and sensory

Question 5

Outline the muscular derivatives of the pharyngeal arches

Answer 5

Arch 1 = muscles of mastication

Arch 2 = muscles of facial expression

Arch 3 = stylopharyngeus

Arch 4 = muscles of the pharynx

Arch 6 = muscles of the larynx

Question 6

Outline the cartilage associated with the pharyngeal arches

Answer 6

Arch 1 = mandible

Arch 2 = upper hyoid bone

Arch 3 = lower hyoid bone

Arch 4 = larynx

Arch 6 = larynx

Question 7

Outline the vessels associated with the pharyngeal arches

Answer 7

Arch 1/2 = disappear

Arch 3 = internal carotid

Arch 4 = arch of aorta, brachiocephalic A

Arch 6 = pulmonary arch

Question 8

Where do glandular structures start to devel in the head and neck region?

Answer 8

In pharyngeal pouches lined with endoderm on the inside of the developing pharyngeal pouches

Question 9

What does the 1st pharyngeal pouch become?

Answer 9

Tympanic cavity

Question 10

What does the 1st pharyngeal cleft become?

Answer 10

External acoustic meatus

Question 11

How are all the pharyngeal clefts (apart from no.1) obliterated?

Answer 11

2nd arch grows down to cover the others

Question 12

What processes drive the devel of the nose and face?

Answer 12

Expansion of the cranial neural tube

Question 13

What embryonic structures make up the face?

Answer 13

Buccopharyngeal membrane = will rupture due to no mesoderm, open into oral cavity

Facial primordia = 1st pharyngeal arch + frontonasal prominence

Primordia of eyes

Question 14

What does the frontonasal prominence devel into?

Answer 14

Forehead

Bridge of nose

Nose

Philtrum

Question 15

What does the maxillary prominence devel into?

Answer 15

Cheeks

Lateral upper lip

Lateral upper jaw

Question 16

What does the mandibular prominence devel into?

Answer 16

Lower lip

Jaw

Question 17

Briefly outline how the nose forms?

Answer 17

Nasal placodes appear = nasal pits

Medial/lateral nasl prominences form either side of the pits

Maxillary prominences push nasal prominences closer together in the midline

Medial nasal prominence then fuse

Question 18

How is the nasal and oral cavity separated?

Answer 18

2 palatal shelves fuse to form = secondary palate

Grows into the oral cavity from the maxillary prominences

Question 19

What is lateral cleft lip?

Answer 19

Affecting the lip alone

Failure of fusion of medial nasal prominence and maxillary prominence

Question 20

What is cleft lip and cleft palate?

Answer 20

Affecting thew lip and palate

Failure of fusion of medial nasal prominence and maxillary prominence

Combined with failure of palatal shelves to meet in midline

Question 21

What is a brachial cysts?

Answer 21

Occur due to remnants of pharyngeal clefts that are usually obliterated

Allows tissue fluid to collect – closed cavity

Occur on anterior border of SCM

Question 22

What is a fistulae in the face neck?

Answer 22

Occur due to remnants of pharyngeal clefts that are usually obliterated

Allows tissue fluid to collect – opening out to the surface of the neck

Occur on anterior border of SCM

Question 23

Briefly outline the formation of the ear

Answer 23

1st pharyngeal pouch = Tympanic cavity

1st pharyngeal cleft = External acoustic meatus

External ear initially in the neck = mandible grows and ears ascend to side of the head

Question 24

Outline foetal alcohol syndrome

Answer 24

Neural crest cells that the facial skeleton is derived from = very sensitive to alcohol

Facial features = flat face, small head, smooth philtrum, short nose, small eyes