Head & Neck Embryology

Question 1

Where does the neck develop from?

Answer 1

Branchial/ Paryngeal arches

Question 2

Where does the face develop from?

Answer 2

From 5 mesenchymal processes / prominences

Question 3

Where does the skull develop from?

Answer 3

From the mesenchyme in the head region of developing embryo

Question 4

What is mesenchyme?

Answer 4

It is an embryonic connective tissue. Has the same properties as a connective tissue and develops into bone, cartilage, blood vessels etc

Question 5

What are somites derived from?

Answer 5

From the paraxial mesoderm

Question 6

What do somites form?

Answer 6

Form structures like upper and lower limbs, vertebral body and they also take part in the formation of the cranial skeleton

Question 7

In the human embryo, how many somites are there?

Answer 7

33

Question 8

What do you need to start developing the head and neck?

Answer 8

1. You need to develop a face to house the special sense organs such as the eyes
2. Skull cap and base of skull to cover and protect the brain
3. Palate to separate mouth from nose
4. Muscles, skeletal elements to support the neck region

Question 9

What are pharyngeal / branchial arches?

Answer 9

They are a series of arches which develop around the future mouth and pharynx.

Question 10

In human, how many branchial arches develop?

Answer 10

Initially, six arches start to develop but arch number 5 disappears so we are left with arches 1, 2, 3, 4 and 6

Question 11

What embryological tissues make up the Branchial Arches?

Answer 11

Ectoderm
Mesoderm
Endoderm
Skeletal Element
Artery
Nerve

Question 12

In branchial arches, what do ectoderm, mesoderm and endoderm form?

Answer 12

Ectoderm - forms clefts in between arches
Mesoderm - forms. Artilage and muscles
Endoderm - forms pouches in between arches

Question 13

What are the nerves of branchial arches?

Answer 13

Nerve of the 1st arch is mandibular branch of trigeminal

2nd ➡️ facial nerve

3rd ➡️ glossopharyngeal nerve

4th ➡️ superior laryngeal branch of vagus

Remember there is no 5th nerve

6th arch ➡️ recurrent laryngeal branch of vagus

Question 14

Give more examples of mother structure which develop from the branchial arches

Answer 14

Tongue
Thyroid gland
Parathyroid gland
Part of the pituitary gland

Question 15

The face develops from 5 processes / prominences. What are they?

Answer 15

1 Frontonasal process
2 Maxillary Processes
2 Mandibular Process

Question 16

True or false - the 2 mandibular processes fuse to form the 1st arch

Answer 16

True

Question 17

How are paternal and medial nasal processes form?

Answer 17

Forms from the nasal pit dividing the Frontonasal process into lateral nasal process and medial nasal process

Question 18

What is Philtrum?

Answer 18

The medial nasal process further grows downwards and laterally, to form a process known as Philtrum

Question 19

Explain the development of the palete

Answer 19

Stage 1: medial nasal process grows downwards and forms Philtrum. This forms the primary palate

Stage 2: from the maxillary process, two palatine shelves grow inwards

Stage 3: the palatine shelves meet in the midline to form the secondary palate

Now the oral cavity and nasal cavity are separates