Week 2 - Embryology and Support Systems

Question 1

Somites

Question 2

Developing spinal cord

Question 3

Developing spinal cord layers

Question 4

Alar plate and basal plate

Question 5

Adult spinal cord

Question 6

Fate of neural crest cells

Question 7

Dermatomes and myotomes

Question 8

3 primary brain vesicles

Answer 8

The proximal, cranial end (neurocoel) of the neural tube enlarges and differentiates into 3 primary brain vesicles:
* Prosencephalon - forebrain
* Mesencephalon - midbrain
* Rhombencephalon - hindbrain
These vesicles are precursors to the major brain regions

Question 9

5 secondary brain vesicles

Answer 9

By week 4, each primary vesicle undergoes further differentiation to form:
* Telencephalon - develops into the cerebral hemispheres
* Diencephalon - contributes to structures like the thalamus and hypothalamus
* Mesencephalon - does not undergo much change, gives rise to the midbrain
* Metencephalon - develops into the pons and cerebellum
* Myelencephalon - forms the medulla oblongata

Question 10

Pharyngeal arches definition

Answer 10

• Paired structures that appear on either side of the developing embryo’s pharynx during the early stages of embryonic development
• There are 6 pairs of pharyngeal arches
  *Each pharyngeal arch gives rise to specific structures in the head and neck region (bones, muscles, skin)

Question 11

First pharyngeal arch

Answer 11

• Gives rise to the mandibular and maxillary components of the jaw, as well as muscles and nerves associated with mastication
• Supplied by mandibular nerve

Question 12

Second pharyngeal arch

Answer 12

• Contributes to the formation of the hyoid bone, and facial muscles
• Supplied by facial nerve

Question 13

Third pharyngeal arch

Answer 13

• Contributes to form the stylopharyngeus muscle, which is involved in swallowing
• Provides sensory supply of the back of the tongue, back of the throat, and middle ear
• Supplied by glossopharyngeal nerve

Question 14

Fourth and sixth pharyngeal arch

Answer 14

• Play roles in the development of the thyroid and parathyroid glands, laryngeal cartilages, and muscles associated with speech and swallowing
• Supplied by vagus nerve

Question 15

Fifth pharyngeal arch

Answer 15

• Transient structure that does not contribute significantly to the development of mature structures
• It is present briefly during early embryonic development but regresses as the embryo develops