Oral Developmental Biology: Arches Flashcards
What is Developmental Biology?
Developmental Biology is the study of the processes by which organs grow and develop. Modern developmental biology studies the genetic control of cell growth, differentiation and morphogenesis, which is the process that gives rise to tissues, organs and anatomy, but also regeneration and ageing
What are the 4 fundamental aspects of Developmental Biology?
- Proliferation/Growth-size
- Pattern formation: is the process by which cells in a developing embryo acquire identities that lead to a well ordered spatial pattern of cell activities.
- Morphogenesis-shape
- Differentiation-type
What are dynamic, reciprocal and sequential interactions?
- Sequentially, timing of events
- Reciprocal, one in control then other
- Dynamic, happen quickly
Tissue interactions appear to be associated with at least 2 general types of phenomena, what are they?
Instructive: the ability of one tissue to determine specific patterns of morphogenesis and differentiation that will develop in an associated tissue.
Permissive (or facilitative): the ability of an interacting tissue to provide certain conditions that is necessary for its committed partner tissue to progress to full expression of its predetermined phenotype
What are the Primary Germ Layers?
- Ectoderm-skin, neural tube, etc this comes from the Epiblast layer
- Mesoderm-just about everything else and is from migratory cells of the epiblast layer
- Endoderm-gut – this come from the hypoblast layer
- Neural Crest / Ecto-mesenchyme is from the ectoderm that migrates into mesoderm to form structures in head and neck
When do Pharyngeal Arches begin to appear?
Appear in 4th and 5th week
What does a Pharyngeal Arch consits of?
- Ectoderm - Outside
- Endoderm – inside (except 1st Arch)
- Cartilage
- Blood vessels and Nerve
- Muscle
What is the first pharyngeal arch?
1st Pharyngeal Arch
“Mandibular arch”:
- Mandibular and maxillary process
Cartilage: Meckel’s Cartilage:
Primitive support, largely disappears
Forms:
2 bones:
- Incus
- malleus
2 ligaments:
- Sphenomandibular
- Sphenomalleolar
What does the 1st Pharyngeal Arch give rise to and what are the nerves and arteries?
Gives rise to:
Body of tongue
Muscles of mastication:
- Temporalis, masseter, pterygoids
- Mylohyoid, anterior body of digastric
Nerve: V (Trigeminal)
Maxillary and Carotid arteries
What is the 2nd arch? What are the arteries and nerves?
Hyoid Arch
Cartilage: Reichert’s cartilage
Forms:
- Stapes
- Lesser horn and superior hyoid body
- styloid process, stylohyoid ligament
Muscles: facial expression and Posterior belly of digastric
Thyroid gland and tonsil
Nerve: VII (Facial)
What does the 3 arch form and what is the muscle and nerve?
Forms:
- greater horn of hyoid
- inferior hyoid body
Forms root of the tongue
Stylopharyngeus muscle
Nerve: IX - Glossopharyngeal
What is the 4th arch muscle and nerve and what does it form?
Forms thyroid cartilage
Pharynx and epiglottis
Muscles:
- Pharyngeal constrictor
- soft palate
Nerve: X (vagus) - sup. laryngeal
What happens with the 5th arch?
Rapidly disappears
What is the 6th arch nerve and cartilages?
- Cricoid + arytenoid cartilages
- Larynx
- Muscles of larynx
- Nerve: vagus X – inf. laryngeal nerve
