Development of tongue Flashcards
a median triangular
elevation appears in the floor of the primordial pharynx
just rostral to the foramen cecum at what week
At the end of the fourth week
What is the name of this elevation
median lingual swelling or tongue bud or tuberculum impar
two lateral
lingual swellings develop on each side of
the median lingual swelling.
The lateral lingual swelling is also known as
distal tongue buds
Where does the 3 swellings arise from
the proliferation of mesenchyme in ventromedial parts of the first pair of pharyngeal arches
The two lateral lingual swellings overgrow the
medial lingual swelling and merge with each other to form
anterior two-third of the tongue
or oral part
The line of fusion
of two lingual swellings in the median plane form
median sulcus on the dorsal surface of the tongue.
What does the tubercular impar form
does not form any recognizable part of the adult tongue.
The
fusion site of the swellings is indicated by
the midline
groove/median sulcus and internally by the fibrous lingual septum.
anterior
two-third of the tongue develops from
1st pharyngeal arch
mucus membrane and taste buds of anterior two-third of the tongue is innervated by
lingual division of mandibular branch of
trigeminal nerve
chorda tympani branch of facial nerve.
The posterior one-third of the tongue develops from
cranial part of
hypobranchial eminence.
The copula forms by fusion of
the ventromedial parts of the second pair of pharyngeal arches.
The hypopharyngeal eminence develops caudal to the
copula from mesenchyme in the ventromedial parts of the
third and fourth pairs of pharyngeal arches.
posterior one-third of tongue develops from
3rd pharyngeal arch
The line of fusion of the anterior two-third and posterior one-third of the tongue is indicated by
a V-shaped
groove—the sulcus terminalis
mucus membrane and taste buds of posterior one-third of tongue is innervated by
glossopharyngeal nerve
What nerve accompanies the myoblasts during their migration and innervates the tongue muscles as they develop
hypoglossal nerve
The muscles of tongue develop from
myoblasts that migrate into developing tongue from the 2nd to 5th occipital myotomes
Lingual papillae appear toward the end of
the eighth
week
Which papillae appear first
circumvallate and foliate papillae
circumvallate and foliate papillae lie where
lie close to terminal branches of the glossopharyngeal nerve
Why is the 2nd arch not involved with development of tongue
There is overgrowth of third arch over the second arch, so the second arch is buried under third arch.
The fungiform papillae appear later near
terminations of the chorda tympani branch of the facial
nerve
Circumvallate papillae forms from
cranial part of hypopharyngeal eminence
Filiform papillae develop when
10th to 11th week
Filiform papillae contain
afferent nerve endings that are sensitive
to touch.
Taste buds develop during
weeks 11 to 13
Taste buds develop
in relation to the terminal
branches of nerves carrying taste sensations (chorda tympani, glossopharyngeal, and vagus nerves)
Clinical correlates
Aglossia (absence of tongue): It is very rare and occurs due to complete agenesis of tongue primordia.
Hemiglossia (half tongue): It occurs if one of the lingual
swelling fails to develop.
Microglossia: Tongue is too small.
Macroglossia: Tongue is too large.
Tongue tie (ankyloglossia): It occurs when frenulum of tongue extends to the tip of the tongue, thus preventing its protrusion and causing difficulty in speech
Mucous membrane and taste buds of the posterior most part of the tongue is innervated by
Superior laryngeal nerve
What separates the developing tongue from the floor of the mouth
linguogingival
sulcus
Hypopharyngeal eminence overgrows what
Copula
