W2 Embryology facial structures

Question 1

Define Stomatodeum membrane

Answer 1

Formed by invagination of ectoderm tissues (noticeable by the end of the third week)

Question 2

Define Oropharyngeal membrane

Answer 2

Composed of ectoderm and endoderm, itseparates the foregut from the stomodeum

Question 3

Describe the formation of the face, referring to the frontal, maxillary and mandibular processes, the development of the nose, lip and angle of mouth

Answer 3

Fusion of all process:

The upper lip - result of fusion between maxillary and globular processes; the lip is fused at 8 weeks.

Angle of the mouth: forms as a result of fusion of the maxillary and mandibular processes

Mandibular arch - result of both mandibular processes fusing together.

Question 4

What is Rathke’s pouch?

Answer 4

Invagination of stomodeal ectoderm in the roof of the stomodeum that moves towards the base of the brain eventually becoming the anterior lobe of the pituitary gland.

Question 5

Describe the formation of the palate

Answer 5

Development of the palate can be divided into primary and secondary palate.

Palatal processes branch off the maxillary process and grow inferiorly along the developing tongue.

When the tongue drops into the floor of the mouth the palatal shelves elevate to a horizontal position.

Question 6

Describe how the multiple nerve innervation of the tongue has embryological origins

Answer 6

Multiple pharyngeal arches contribute towards the formation of tongue resulting in mixed innervation.

• Anterior 2/3 of the tongue: Cranial Nerve V Cranial nerve VII Posterior 1/3 of the tongue: Cranial nerve IX - sensory and taste
• Motor supply to the whole tongue: cranial nerve XII

Question 7

What is the medial nasal process?

Answer 7

The medial nasal processes merge with the maxillary prominences.

At it’s lower border, the median nasal process grows in length and produces a pair of bulges called the globular process. This grows downward (philtrum) and the anterior part of the palate.

Question 8

What is the primary palate?

Answer 8

Horizontal shelf separating nasal pits from stomodeum, continuous with primitive. Made up of 4 incisor teeth

Question 9

What is the secondary palate?

Answer 9

Secondary: shelf like out growths from maxillary process (palatine process). Canine and posterior teeth

Question 10

What is the secondary palate?

Answer 10

Secondary: shelf like out growths from maxillary process (palatine process). Canine and posterior teeth

Question 11

What is Macrostomia?

Answer 11

Larger than normal mouth. Cause: Incomplete fusion between maxillary and mandibular process. This can be unilateral or bilateral. In some cases can be corrected by surgery

Question 12

What is Median cleft/cleft chin?

Answer 12

Result pf incomplete fusion of mandibular processes as they come together at the midline

Question 13

Describe cleft clip

Answer 13

Due to failure of fusion of maxillary and globular processes, can be unilateral or bilateral

Question 14

Describe cleft palate

Answer 14

Occurs if fusion does not take place between the palatine process (or both and the median nasal process, creating an opening between nasal or oral cavities.

Question 15

Describe cleft palate

Answer 15

Occurs if fusion does not take place between the palatine process (or both and the median nasal process, creating an opening between nasal or oral cavities.

Question 16

Describe ankyloglossia

Answer 16

A short lingual frenum 4%-11% of newborns; difficult for breast feeding

Question 17

Describe Bifurcation

Answer 17

Lingual swelling of the first branchial arch have failed to merge

Question 18

What do the 5 pharyngeal arches contain?

Answer 18

An artery, artilage, cranial nerve and mesodermal tissues.

Arches 1-4 involved in development of face and oral cavity structures

Question 19

Describe 1st pharyngeal/branchial arch

Answer 19

It is the mandibular arch formed by fusion of maxillary process and mandibular process. It has trigeminal nerve and muscles of mastication

Question 20

Describe the 2nd pharyngeal arch

Answer 20

The hyoid arch, it has the facial nerve and muscles of facial expression

Question 21

Describe the 3rd paryngeal arch

Answer 21

It has the Glossopharyngeal nerve and stlopharyneus muscle

Question 22

Describe the frontal process

Answer 22

Large bulge of ectoderm and mesoderm forming above the stomatodeum/stomodeum forming upper part of face, nasal septum and anterior palate.

Lower part is divided into 3 section:

• 2 Lateral nasal
• 1 median nasal process (forming the tip of npse, primary palate and nasal septum)

Question 23

Describe the median nasal process

Answer 23

It grows in length producing pair of bulges (GLOBULAR PROCESS) this grows downward below olfactory puts to form the centre of lip (philtrum) and anterior portion of the palate (primary palate)

Question 24

What (2) nerve supplies the anterior 2/3 of the tongue?

Answer 24

(V) Trigeminal: general sensory

(VII) Facial nerve: taste

Question 25

What nerve supplies the posterior 1/3 of the tongue?

Answer 25

(IX) Glossopharyngeal: general sensory and taste

Question 26

What nerve supplies motor innervation to the WHOLE tongue?

Answer 26

(XII) Hypoglossal nerve