Development of the Midline Structures Flashcards
Describe the location of the pituitary gland
Sphenoid bone
In hypophyseal fossa of the sella turcica
Describe the pituitary gland
2 in 1 gland
P = neuroendocrine secretion
A = endocrine secretion – portal hypophysial vessels
Where does the pituitary gland arise from?
A = rathke’s pouch - ectoderm
P = infundibulum – neuroectoderm
Where does the infundibulum devel from?
Neural tube component = downward growth of forebrain
Grows towards roof of pharynx
Where does rathke’s pouch devel from?
Out-pouching of ectoderm of stomatoderm
Evagination of roof of oropharynx
Grows dorsally towards developing forebrain
Where does the tongue devel from?
All 5 pharyngeal arches
Lateral lingual swellings over-grow the tuberculum impar
The 3rd arch component of the cupola over-grows the 2nd arch component
Extensive degeneration occurs, freeing tongue from the floor of the oral cavity
How is the tongue tethered to the floor of the oral cavity?
Lingual frenulum
What line demarcates the division of the tongue into the anterior 2/3 and posterior 1/3?
Sulcus terminalis
What nerve enables the special sensory innervation of the tongue?
CN VII – facial
Chorda tympani branch passes through middle ear
Where do muscle of the tongue arise from?
Myogenic precursors that migrate into the developing tongue
CN XII
Where does the thyroid gland devel from?
Devel in oropharynx floor
Between 2 early components of devel tongue (tuberculum impar + cupola)
From midline diverticulum
How is the thyroid gland connected to the tongue during development?
Patent tube = thyroglossal duct
How does the thyroid gland reach its final position?
Bifurcates and descends as a bi-lobed diverticulum connected by the isthmus
What thyroid abnormalities exist?
Thyroglossal cysts – duct doesn’t close, collects fluid, creates cyst
Ectopic thyroid tissue
What embryonic structures contribute to the development of the face?
Frontonasal nasal prominence and the 1st and 2nd pharyngeal arches
