Head and Neck Session 11 Flashcards
how does the post. lobe of pituitary arise?
from developing brain: downgrowth from diencephalon forms in midline= infundibulum, and extends down towards roof of oral cavity,
name given to downgrowth of diencephalon from which P lobe of pituitary arises?
infundibulum
how is floor of hypothalamus formed?
from part of diencephalon giving rise to infundibulum
what name is given to connection between floor of hypothalamus and infundibulum forming P lobe of pituitary?
pituitary stalk
name given to outpushing from roof of oral cavity which grows up to meet forming infundibulum?
Rathke’s pouch
what may form from persitent remnants of Rathke’s pouch in the roof of the pharynx from where it split off from the ectoderm from which it was derived?
cysts
how do the tongue and thyroid gland arise from pharyngeal arches?
from where they meet as they curve around lateral walls of mouth and pharynx, meeting in the midline ventrally
which 3 components form the anterior 2/3 of the tongue?
median tongue bud from floor of pharynx at level of 2nd pharyngeal arch- facial nerve
paired distal tongue buds form in front of median bud and eventually overgrow and absorb it. originate from 1st pharyngeal arch- trigeminal nerve
which 2 components form posterior 1/3 of tongue?
copola- forms in midline from 2nd pharyngeal arch
hypobranchial eminence- forms from 3rd and 4th arches behind copola. Expands and absorbs copola, forming post 1/3 tongue (3rd arch- glossopharyngeal nerve) and epiglottis (4th arch)
what is seen in adult at site of fusion of A and P parts of tongue?
sulcus terminalis
muscles of tongue are NOT derived from pharyngeal arches. where do they arise from?
small somites (paraxial mesoderm) which arise in occipital region and migrate into developing tongue
name given to site of origin of thyroid?
foramen cecum
name of epithelial outgrowth in 4th wk that gives rise to thyroid?
thyroid diverticulum
where is the foramen cecum?
between 1st and 2nd pharyngeal arches, behind median tongue bud
on descent, how does the thyroid remain attached to the foramen cecum?
via the thyroglossal duct
what may form as a remanant of the distal end of the thyroglossal duct?
pyramidal lobe of thyroid
the foramen cecum closes off, but how is it seen in adult?
indentation on dorsum of tongue
calcitonin producing cells of thyroid originate from where?
4th pharyngeal pouch-ventral part
most common site for thyroglossal cysts?
base of tongue and just inferior to hyoid
most common site of ectopic thyroid tissue due to failure of thyroid to descend normally?
tongue
when might the isthmus of the thyroid need to be incised?
during a tracheostomy to expose the trachea to keep the airway patent
what is the nasopharynx attached to superiorly?
base of skull
the wall of the pharynx has an outer incomplete circular muscle layer, and an inner longitudinal layer, what 3 muscles comprise the inner layer?
stylopharyngeus-from 3rd arch
palatopharyngeus
salpingopharyngeus
the 3 named tonsils comprising the incomplete ring of lymphoid tissue in the pharynx?
palatine- between palatoglossal and palatopharyngeal ridges
adenoids (pharyngeal)- near roof of nasopharynx close to ET entry
lingual- beneath mucosa of P 1/3 of tongue
how is food forced into oesophagus?
by automatic contraction of the 3 pharyngeal constrictor muscles
which muscles contract to elevate the larynx during swallowing?
suprahyoid muscles
longitudinal pharyngeal muscles= stylopharyngeus, palatopharyngeus, salpingopharyngeus
2 important structures vulnerable to injury in tonsillectomy?
ICA
glossopharyngeal nerve
arterial b.supply to tonsil?
tonsillar branch of facial artery
common site where FBs entering pharynx may become lodged?
piriform fossa
what does the posterior wall of the pharynx lie against?
prevertebral layer of deep cervical fascia
what does the nasopharynx lie superior to?
soft palate
what may a pharyngeal pouch (diverticulum of zenker) in the pharynx cause?
dysphagia
regurgitation of food
halitosis-bad breath
what nerve plexus supplies the pharynx and what does it comprise?
pharyngeal
pharyngeal branches of vagus, glossopharyngeal, and sympathetoc branches from S.cervical ganglion
sensory innervation to nasopharynx?
maxillary division of trigeminal