10.1 Development 3 Flashcards
Where does the pituitary gland sit?
Sella turcica/pituitary foss aof sphenoid bone above the cavernous sinus.
What is the anterior lobe of the pituitary called? Where does it develop from? Tissue?
Adenohypophysis
Rathke’s pouch
Ectoderm
What is the posterior lobe of the pituitary called? Where does it develop from? Tissue?
Neurohypophysis
Infundibulum
Neuroectoderm.
Describe the development of the poster lobe.
The posterior lobe is formed from a down growth from the diencephalon in the midline - the infundibulum.
Infundibulum extends down towards the roof of the developing oral cavity, retaining its connection with the diencephalon.
What does the part of the diencaphlon from which the infundibulum arises become? Connection between infundibulum and diencephalon?
Hypothalamus
Pituitary stalk
What is Rathke’s pouch? how does it devleop?
An out pushing from the roof of the oral cavity that grows upwards to meed the infundibulum.
Loses its connection with the roof of the mouth and comes to lie anterior to the infundibulum and wrap around the pituitary stalk.
Differentiates into endocrine cells of anterior pituitary.
What functionally links the anterior lobe to the hypothalamus and the posteror lobe?
hypophyseal portal system of blood vessels.
When does the tongue appear?
4th week
Describe the development of the tongue.
Branchial arches curve around the lateral walls of mouth and pharynx.
Left and right arches meet in the midline ventrally.
The tongue and thyroid gland arise where the branchial arches meet.
5 components come together in tongue development.
What are the 5 components that develop into the tongue? What do they develop from?
2 lateral lingual swellings of 1st pharyngeal arch.
3 medial swellings: 1st arch - tuberculum impar 2nd/3rd arches: Cupola 4th arch Epiglottal swelling
Describe how the lingual swellings develop into the tongue.
Lateral lingual swellings overgrow the tuberculum impar.
Cupola from 3rd arch grows over the 2nd arch component.
Extensive degeneration occurs, freeing the tongue from the floor of the oral cavity, except from the lingual frenulum.
Describe the development of the anterior 2/3 of the tongue.
Tuberculum impair forms from the floor of the pharynx atht he level of the 2nd arch.
Paired distal tongue buds from the 1st arch form in front of the tuberculum impair and eventually overgrow and absorb it.
Describe the development of the posterior 1/3 of the tongue.
Single swelling, cupola forms in the midline from the 2nd arch.
Larger swelling, hypobranchial eminence forms from the third and fourth arches behind the cupola.
Hypobranchial eminience expands and absorbs the cupola forming the posterior 1/3 (3rd arch) and the epiglottis (4th arch)
Give the innervation of the tongue, general and special sensory and motor.
Gen
Ant 2/3 = lingual branch of CNV3 (1st arch nerve)
Post 1/3 = lingual branch of CNIX (3rd arch nerve)
Special
Ant 2/3 Chorda tympani of CNVII (2nd arch nerve –> 1st arch via middle ear))
Post 1/3 = Ligual branch of CNIX (3rd arch nerve)
Motor
All muscles = hypoglossal nerve CNXII
Except palatoglossus = CNX
Where does the thyroid gland first appear? When?
Floor of pharynx between tuberculum impair and cupola in 4th week.
