Embryology Lecture

Question 1

During what weeks does organogenesis occur?

Answer 1

Weeks 4-8

Question 2

During what week does gastrulation occur?

Answer 2

Week 3

Question 3

During what time period does neurulation occur?

Answer 3

Week 3, over by week 4

Question 4

What structure tells the ectoderm to differentiate into the neuroectoderm?

Answer 4

Notochord

Question 5

What structures does the forebrain (prosencephalon) swell into?

Answer 5

Diencephalon
Telencephalon

Diencephalon becomes hypothalamus/thalamus and 3rd ventricle

Telencephalon becomes cerebral hemispheres , basal ganglia and lateral ventricles

Question 6

What structures does the midbrain (mesencephalon) swell into?

Answer 6

Mesencephalon becomes the midbrain and cerebral aqueduct

Question 7

What structures does the hindbrain (rhombencephalon) swell into?

Answer 7

Becomes the metencephalon and myelencephalon

Metencephalon becomes the pons, cerebellum and upper part of 4th ventricle

Myelencephalon becomes the medulla and the lower part of the 4th ventricle

Question 8

What are the muscles, cranial nerves, arteries cartilage and bones of pharyngeal arch 1?

Answer 8

o	Pharyngeal arch 1 (mandibular arch)
	Muscles: Mastication
	Cranial Nerve: Trigeminal (V)
	Artery: (Aortic arch 1)
	Cartilage: Meckel’s 
	Bone: Maxilla, mandible, malleus, incus, contributes to tympanic membrane and auricle of ear

Question 9

What are the muscles, cranial nerves, arteries cartilage and bones of pharyngeal arch 2

Answer 9

 Muscles: Facial expression, posterior belly of digastric, sylohyoid, stapedius
 Cranial Nerve: 7
 Arterial: Aortic arch 2: hyoid and stapedial
 Bone: Stapes, styloid process, styloid ligament, upper body of hyoid and lesser horn of hyoid. Contributes to auricle of ear

Question 10

What are the muscles, cranial nerves, arteries cartilage and bones of pharyngeal arch 3

Answer 10

 Muscles: Stylopharyngeus
 Cranial Nerve: IX
 Arterial: Arch 3 (internal and common carotids)
 Bone: Lower body of hyoid, greater horn of hyoid

Question 11

What are the muscles, cranial nerves, arteries cartilage and bones of pharyngeal arch 4/6

Answer 11

	Muscles: Pharyngeal and laryngeal (swallowing and speaking) except stylopharyngeus and tensor veli palatini
	Cranial Nerve: 10
	Arterial
•	Aortic arch 4
o	L-Arch of the aorta
o	R- Right subclavian
•	Aortic Arch 6
o	Left: Left pulmonary artery & ductus arteriosus
o	Right: Right pulmonary artery
	Cartilage:
•	Arch 4: Upper thyroid cartilage
•	Arch 6: Lower thyroid cartilage and cricoid cartilage

Question 12

What structures does pharyngeal cleft 1 give rise to

Answer 12

External auditory meatus

Part of the tympanic membrane

Question 13

What are the 5 prominences of the face and what they give rise to?

Answer 13

o Lateral nasal: Alae of nose
o Medial nasal: Philtrum of upper lip, crest, and tip of nose
o Frontonasal: Forehead, bridge of nose, media and lateral nasal prominences
o Mandibular prominence: Lower lips
o Maxillary prominence: Cheeks, lateral portion of upper lips