Anatomy- Skull/Face/Palate development

Question 1

What is a synchondrosis?

Answer 1

A join where there is a layer of hyaline cartilage between 2 joints.

It is found on growth plates. When the plate stops growing (the cartilage is converted into bone

Question 2

What is an ossification centre and how many of them are there in the skull?

Answer 2

An ossification centre is where bone develops from.

There are 6 of them in the skull:

Parts 3 and 4 are fused by birth (intramembranous ossification)

Parts 1 and 2 fuse by endochondral ossification.

Question 3

Name the fontanelles of the skull and state when they close.

Answer 3

Posterior fontanelle- closes at 2 months

Sphenoidal fontanelles - close at 6 months

Mastoidal fontanelles- close at 6-18 months

Anterior fontanelle- close at 2 years

Question 4

Label this diagram of the fetal skull

Answer 4

A- Metopic suture

B-Coronal suture

C-mental symphasis

D-Anterior fontanelle

E- Saggital suture

F-Lambdoid suture

G- Coronal suture

H- posterior fontanelle.

Question 5

Discuss the mental symphysis?

Answer 5

Normally open at birth but fuses at 1 year.

If you can still see it, the mental symphysis is fibrous.

Question 6

When does the metopic suture close?

Answer 6

2-4 years

Question 7

Label this diagram of the adult skull

Answer 7

A- temporal

B- zygomatic

C- maxilla

D- mandible

E- Frontal

F- Coronal suture

G- Parietal

H- Lambdoid suture

I- Bregma

J- Sagittal suture.

K- Lambda

Question 8

What causes the production of the bregma?

Answer 8

The closure of the anterior fontanelle.

Question 9

What causes the production of the lambda?

Answer 9

The closure of the posterior fontanelle.

Question 10

Compare the fetal skull to the adult skull.

Answer 10

• Angle of the mandible in the fetal skull is more obtuse.
• The fetal skull has the sphenoidal fontanelle which closes over in an adult to form the pterion.
• The tempanic ring in a fetus develops into the tympanic plate in an adult.

Question 11

When does the face develop?

Answer 11

4- 8 weeks in utero

Question 12

When does the palate develop?

Answer 12

6-10 weeks in utero

Question 13

What is a pharyngeal arch?

Answer 13

This is a tissue outgrowths that contribute to the structures of the face and ears.

Question 14

Which pharyngeal arch is responsible for facial development?

Answer 14

1st pharyngeal arch:

Forms :

The trigeminal nerve

Muscles of mastication

Malleous and incus of middle ear

Meckle’s cartilage.

Question 15

Name the 5 prominences that form the face?

Answer 15

Frontonasal prominence

Maxillary promience

Medial nasal prominence

Lateral nasal prominence

Mandibular promience.

Question 16

Describe how the nose develops?

Answer 16

The nasal placodes form the olfactory epithelium.

The nasal promiences produce nasal pits that become the nostrils.

The medial nasal promiences fuse together to form the tip of the nose.

The lateral nasal promiences forms the wings of the nose.

The frontonasal promience forms the bridge of the nose.

Question 17

Describe how the maxillary and mandibular promiences form the face?

Answer 17

Maxillary promience forms the cheeks

Maxillary promience fuses with the medial nasal to form upper jaw

Mandibular prominence fuses to form jaw and lower lip.

Chin is produced when the 2 mandibular promiences fuse.

Fusion of the maxillary and mandibular prominences form the corner of the mouth.

Question 18

What does the palate form from?

Answer 18

2 parts: the primary and secondary palate.

Question 19

How does the primary palate form?

Answer 19

The medial nasal processes form the intramaxillary processes which gives rise to the primary palate and the philtrum of the lip.

Question 20

How is the secondary palate formed?

Answer 20

The maxillary promiences form the palatal shelves.

The palatal shelves fuse to form the secondary palate.

This seperates the nasal and oral cavities.

Question 21

What causes cleft lip?

Answer 21

Failure of fusion of the medial nasal promience and the maxillary prominence.

Question 22

What causes cleft palate?

Answer 22

Failure of fusion of the 2 palatal shelves.