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Flashcards in Embryology of Head Deck (15)
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1

What bones form the neurocranium? How are they formed?

Frontal, parietal, squamous portion of temporal, interparietal portion of occipital

Intramembranous ossification

2

What bones form the viscerocranium? How are they formed?

Facial bones: intramembranous ossification

Ossicles, hyoid: endochondral ossification

3

What bones form the cranial base? How are they formed?

Ethmoid, sphenoid, petrous portion of temporal, occipital

Endochondral ossification

4

What is the spheno-occipital synchondrosis and when does it close?

A fibrous joint between the sella turcica part of the sphenoid and the occipital bone. Allows longitudinal growth. Fuses around 15-17 years.

5

What is the cranial base angle and how does it affect face shape?

The angle between sphenoid and occipital bones.
Predicts the position of the mandible:
large angle associated wtih square jaws and overbites
small angle associated with wide angled mandibles and mandibular protrusion

6

What type of cells converge in the pharyngeal arches?

Mesenchyme and neural crest cells

7

What types of tissues do the cells in the pharyngeal arches produce?

Cranial nerves
Cartilage that may remain cartilage or ossify
Artery (aortic arch)

8

What are the key nerve, muscle, and bony/cartilage structures associated with the mandibular arch?

CN V
Mandible, maxilla, zygoma, malleus, incus, squamous temporal
Muscles of mastication, anterior digastric, tensors tympani and palati

9

What are the main pharyngeal arches?

Mandibular, hyoid, third, and fourth

10

What are the key nerve, muscle, and bony/cartilage structures associated with the hyoid arch?

CN VII
Styloid process, hyoid, stapes
Muscles of facial expression, posterior digastric, stylohyoid, stapedius

11

What are the key nerve, muscle, and bony/cartilage structures associated with the third arch?

CN IX
hyoid
stylopharyngeus

12

What are the key nerve, muscle, and bony/cartilage structures associated with the fourth arch?

CN X
larynx
pharynx, larynx

13

Describe the structures that arise from the pharyngeal grooves and pouches, including any migrations.

Grooves
1: external auditory meatus

Pouches
1: tympanic cavity & auditory tube
2: palatine tonsil
3: thymus and parathyroid glands, migrate down into the neck
4: parathyroid and C cells of thyroid, migrate down into the neck

14

Describe the development and migration of the thyroid gland

Descends from the base of the tongue through foramen cecum and thyroglossal duct, around the front of the hyoid to its final position anterior to the larynx.

15

What are the underlying developmental steps that lead to cleft lip and palate?

The face is formed by medial migration and fusion of maxillary, mandibular, nasomedial, and nasolateral processes.
Cleft lip arises due to failed fusion of maxillary and medial nasal prominences.
Cleft palate is due to failed fusion of palatine processes.