Session 10- The pharynx and development of midline structures Flashcards Preview

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Flashcards in Session 10- The pharynx and development of midline structures Deck (98):

Where even is the pharynx?

  • Muscular tube from the base of the skull down to C6
  • Forms the upper alimentary canal 
  • Posterior to the nasal and oral cavities
  • Posterior wall of pharynx is against the prevertebral layer of deep cervical fascia 


where is the pharynx widest and narrowest?

  • Upper end is widest
  • Narrowest inferiorly where is becomes continuous with the oesophagus 


What are the superior and inferior boundaries of the nasopharynx?

  • Superior: base of skull 
  • Inferior: upper border of soft palate 


what is posterior and anterior to the nasopharynx?

  • Posterior: C1, C2
  • Anterior: Nasal cavity 


What is the contents of the nasopharynx?

  • Pharyngeal tonsil (midline)
    • When these are enlarged they are known as adenoids (can also be known as adenoids but whatevs) 
  • Opening of the eustachian tube 


What does the nasopharynx open into the nasal cavity via?

  • Two chonae (apetures) 


If the adenoids are enlarged what sort of shit can this cause m8?

  • all sorts of shit
    • Block nasal air flow--> mouth breathing and snoring
    • Block eustachian tube opening
    • Harbour chronic infection (can transmit to eustachian tube or sinuses) --> otitis media or sinusitis 


Are adenoids in every1?

No fam 

  • Develop and get bigger till about age of 7 then regress
  • Kind of like levels of happiness lol 


Why is middle ear infection more common in kids?

  • The eustachian tube is:
    • Shorter
    • More horizontal 
  • So ascending infection more likely innit 


 Y does otitis media with effusion occur? Y can it lead to otitis media?

  • Cells in middle ear are constantly reabsorbing nitrogen/oxygen 
  • Blocked ET= negative pressure in middle ear because it normally allows equilibration of air pressure with external ear 
  • Transudate (sterile) is drawn from the mucosa= otitis media with effusion 
  • Then bacteria can proliferate--> otitis media 


Otitis media is a bit uncomfortable and u get a bit of a fever but its not that bad tho is it?

  • Wrong, it is bad m8! (well it can be), complications:
    • Hearing loss:
      • Normally temporary and associated with effusion 
    • Inflammation of the mastoid 
      • Necrosis of the mastoid process (can cause brain abscess, meningitis etc.
    • Cholesteatoma
      • Cyst like lesion, linked to chronic inflammation caused by pocket formation in the attic of tympanic membrane causing proliferation of cells
      • Can erode surrounding structures e.g. ossicles, cochlea 


What are the superior, inferior, anterior and posterior boundaries of the oropharynx?

  • Superior and inferior: soft palate and epiglottis 
  • Anterior: Oral cavity 
  • Posterior: C2, C3


What is in the oropharynx fam?

  • Palatine tonsils (between palatoglossal and palatopharyngeal arches)


What are superior and inferior boundaries of the laryngopharynx tho?

  • superior and inferior:
    • Oropharynx to oesophagus
    • OR epiglottis to cricoid cartilage 


What are the anterior and posterior boundaries of the laryngopharynx?

  • Anterior: larynx
  • Posterior: C4, C5, C6


y is the laryngopharynx so special?

It has mixed functions: GI and Resp 

It's well cool 


What is in the laryngopharynx?

  • Piriform fossa/recess 
    • Either side of inlet to the larynx (airway)
    • They divert fluid around the larynx down into the oesophagus which is nice of them tbh


What is like a difference between the thyroid and cricoid cartilage?

  • Thyroid is only anterior to trachea
  • Cricoid is complete ring so is anterior and posterior 


How many inner longitudinal muscles are involved in the pharynx? what r they? What do they do?

  • 3 of them:
    • Stylopharyngeus 
    • Palatopharyngeus
    • Salpingopharyngeus 
  • they elevate the pharynx and larynx in swallowing and speaking by shortening and widening the pharynx 


What is origin, insertion and innervation (u thought this ended with MSK but it didn't) of stylopharyngeus?

  • Origin: styloid process
  • Insertion: posterior border of thyroid cartilage 
  • Innervation: Glossopharyngeal nerve (CN IX) 


What is the origin, insertion and innervation of palatopharyngeus?

  • Origin: hard palate
  • Insertion: posterior border of thyroid cartilage
  • Innervation: pharyngeal branch of vagus (CN X) 


What is origin, insertion and innervation of salpingopharyngeus?

  • Origin: cartilagenous part of the eustachian tube
  • Insertion: merges with palatopharyngeus 
  • Innervation: pharyngeal branch of vagus (CN X) 


The pharynx also has 3 outer circular muscles. Are they complete circles? What do they do?

  • Obvs not cause I wouldn't ask otherwise 
  • Not complete as the pharynx communicates with anterior structures 
  • BUT circular enough to contract concentrically 
  • They constrict walls of pharynx when swallowing to move the bolus until the oesophagus takes over
    • They relax and contract sequentially from above and below to propel food into the oesophagus 


What are the 3 circular pharyngeal constrictors?

  • superior pharyngeal constrictor
  • Middle pharyngeal constrictor
  • Inferior pharyngeal constrictor, two parts:
    • Thyropharyngeal 
    • Cricopharyngeal 
    • Between these 2 there is a point of weakness= Killian's dehiscence 


What is the innervation of the outer circular pharyngeal constrictors?

Vagus (CNX) 


What is the point at which all the pharyngeal constrictors meet called?

Pterygomandibular raphe 

  • Can see a sort of ridge on the inside of the cheek here 
  • Also kind of extends down back of the neck (can't see that though)



What is a pharyngeal pouch?

  • A posteromedial (false) diverticulum
  • Probs due to:
    • failure of upper oesophageal sphincter to relax
    • Leads to abnormal timing of swallow:
      • Basically higher pressure in laryngophrynx during swallowing due to an attempt to constrict against a closed oesophageal sphincter 
      • Weakness in the inferior contrictor muscles means that this higher pressure causes outpouching 
        • Part of pharyngeal mucosa herniates through Killian's dehiscence forming a pharyngeal pouch 


What are symptoms of a pharyngeal pouch (which kind of looks like a little pony tail lol)?

  • small pouches can be asymptomatic but if food becomes trapped in pouch:
    • Dysphagia
    • Regurgitation 
    • Halitosis= bad breath 


Where is the pharyngeal plexus? What nerves are involved?

  • On surface of middle constrictor muscles
  • Vagus, glossopharyngeal and cervical sympathetic nerves 


Describe the motor innervation of the pharynx 

  • CNX innervates all muscles except stylopharyngeus which is innervated by the glossopharyngeal 


Describe the sensory innervation of the 3 parts of the pharynx?

  • Nasopharynx:
    • Maxillary nerve (CNV2)
  • Oropharynx
    • Glossopharyngeal nerve (CN IX)
  • Laryngopharynx
    • Vagus nerve (CNX) 


waldeyer's ring is an important anatomical relation to the pharynx. Describe this

  • Pharyngeal tonsils, palatine tonsils and lymphoid nodules on the dorsum of the tongue form a continuous lymphoid ring (waldeyer's ring) around the naso- and oro-pharynx


why are upper resp tract infections often complicated by middle ear infections?

  • As pharyngotympanic tube provides a potential route for infection in the pharynx to spread to the middle ear 


Why can tonsillectomy from the tonsilar bed due to recurrent inflammation of the tonsils cause profuse bleeding?

  • as there is a rich blood supply to the tonsils 
  • Via the tonsilar branch of the facial artery 


Why are foreign objects likely to become stuck  when swallowing?

  • The piriform fossae
  • Or inferior end of the laryngopharynx (as it is narrowest) 


What are the 3 stages of swallowing?

  • Oral
  • Pharyngeal 
  • Oesophageal 


Describe the oral phase of swallowing 

  • Voluntary 
  • Preparatory phase (makes the bolus through mastication)
  • Transit phase:
    • Bolus compressed against palate and pushed into the oropharynx by the tongue and soft palate 


Describe the pharyngeal phase of swallowing

  • Involuntary 
  • Tongue is positioned against the hard palate (so food cannot re-enter the mouth)- CNXII
  • Soft palate elevated sealing off the nasopharynx
    • Tensor palatini- CNV3
    • Levator palatine- CNX 
  • Suprahyoid (CNV3, CN VII, CN XII) and longitudinal muscles shorten (CN IX, CNX) 
    • Pharynx widens and shortens to receive bolus
    • Larynx elevated and sealed off by vocal cords
  • Epiglottis closes over the larynx (result of elevated hyoid)
  • Bolus moves through pharynx by sequential contraction of constrictors 
  • Relaxation of upper oesophageal sphincter 


Describe the oesophageal phase of swallowing 

  • Involuntary 
  • Upper striated muscle of oesophagus (CN X)
  • Lower smooth muscle


What are causes of dysphagia which cause more difficulty swallowing liquids than solids?

  • Stroke 
  • Parkinson's/MS (due to problems with muscles/nerves)
  • COPD
  • dementia (global problem with the brain)


What are 30% of post-stroke deaths due to?

Pneumonia- because you can't control your swallow so get aspiration pneumonia 


What are signs and symptoms of dysphagia? (caused by neuro causes)

  • Coughing and choking 
  • Sialorrhoea (drooling)
  • Recurrent pneumonia
  • Change in voice/speech (wet voice)
  • nasal regurgitation 


The swallow assessment is a complex process; what are the different aspects of it?

  • Gag reflex is unreliable as some people have less pronounced reflex
  • Level of conciousness
  • Postural control 
  • Small spoonfuls of water 
  • Speech and language therapist:
    • Full history 
    • Videofluroscopy 
    • Fibre-optic endoscopic evaluation 


what are common interventions which are needed after a stroke due to the dysphagia?

  • Modify consistency of food and fluids (thicker easier to swallow)
  • Modify feeding strategies
  • Indirectly modify swallow techniques 
  • Modify physiology of the swallow mechanism during swallow 
  • Modify posture
  • Improve oral hygeine
  • Increase confidence and reduce fear of choking
  • Educating carers 


What can the pituitary gland also be called?

  • Hypophysis
  • Hypophysis cerebri 


what does the portal hypophyseal system allow?

  • Close communication between the pituitary and the hypothalamus without going into the systemic circulation 


what is the infundibulum?

  • The pituitary has ectoderm and neuroectoderm origins 
  • Neuroectoderm:
    • Out growth of the forebrain grows down towards the roof of the pharynx 
    • This growth is the infundibulum 
  • The infundibulum will give:
    • Connecting stalk 
    • Posterior pituitary 


what is rathke's pouch?

  • An out-pocketing of ectoderm of the stomatodeum 
  • It is an invagination of the root of the oropharynx 
  • It grows dorsally towards the developing forebrain (infundibulum);
    • A circulation system is set up between the two tissue types 
    • At same time there is ossification of the sphenoid and this causes the pouch to be 'pinched' off and the ectoderm from which it is formed fuses with the infundibulum 
  • Rathke's pouch ultimately gives:
    • Anteiror pituitary 


Where does the tongue lie?

  • Partly in the oral cavity and partly in the oropharynx 



The tongue is highly mobile. What connects it to the floor of the mouth?

  • A bit of tissue called the lingual frenulum 


Which  muscles is the tongue made up of?

  • Intrinsic and extrinsic
    • These allow the tongue to move position and change shape 
    • Required for its function e.g. speech 


What two parts is the tongue split into and what by?

  • Anterior 2/3rds and posterior 1/3rd 
  • Marked by a V shaped line 
    • Sulcus terminalis 
  • The point of the V is:
    • Foramen cecum 


When do primordia of the tongue appear?

About the same time as the palate 


Which pharyngeal arches is the tongue made up of? Describe it

  • All of them
  • Two lateral swellings:
    • Pharyngeal arch 1
  • 3 median swellings
    • Arch 1 (most anteiror on tongue): 
      • Tuberculum impar 
    • Arches 2,3 (+4)
      • Cupola 
    • Arch 4 (closest to larynx, at the back)
      • Epiglottal swelling 


What happens to the lateral and medial swellings to form the tongue?

  • Lateral ones over-grow the tuberculum impar (as they grow faster than medial swellings)
  • 3rd arch part of cupola over-grows the 2nd arch component 


After the has been growth of the median and lateral lingual swellings what goes on next?

  • Extensive degeneration (apoptosis), this frees the tongue from the floor of the oral cavity:
    • Not complete in the midline though: lingual frenulum remains to tether the tongue to the floor but it long enough to allow free movement of the tongue 


Describe the sensory innervation of the tongue

  • Muscosa of anterior 2/3rds
    • Pharyngeal arches 1 and 3
    • CNV and IX 
  • Posterior 1/3rd derived from pharyngeal arches 3 (+4)
    • General and special sensory 
    • CNIX and CNX
  • Anterior 1/3rd special sensory (taste buds develop in papillae in the substance of the tongue)
    • Chorda tympani:
      • Branch of CNVII (nerve of arch 2)
      • BUT it passes in 1st pouch
      • SO it passes through the middle ear (as this is the space between the 1st and 2nd arch)


Describe the motor innervation to the tongue 

  • Both intrinsic and extrinsic muscles of the tongue develop from myogenic precursors that migrate into the developing tongue
    • From occiptal somites (have myotomana and sclerotomal derivatives)
    • CN XII innervates the occipital somites so myogenic precursors take this with them and intrinsic and extrinsic muscles of tongue are innervated by CN XII 



Where does the primordium of the thyroid appear compared to where the thyroid ends up?

  • Primordium appears in the floor of the pharynx between the tuberculum impar and the cupola (front two median swellings of the tongue)
  • BUT final position is in anterior neck 


Describe the descent of the thyroid

  • Point of origin for descent is later marked by foramen cecum 
  • Bilfurcates and decsends as a bi-lobes diverticulum connected by the isthmus 
  • during descent the thyroid gland remains connected to the tongue by the thyroglossal duct
  • Also during descent we do not have fully formed laryngeal cartilage so this helps allow movement 



what the heck is a pyrimidal  lobe?

  • Obvious remnant of the thyroglossal duct
    • It extends upwards from the thyroid gland along the path of the thyroglossal duct 


How many people is the pyramidal lobe present in?



What are the constituents of the thyroid gland and what do they derive from?

  • Follicular cells 
    • Produce thyroxine and triiodothyronine
    • Derived from thyroid diverticulum (embryological structure on the 2nd pharyngeal arch)
  • Parafollicular cells (C cells)
    • Produce calcitonin
    • Ultimobranchial body of the 4th pharyngeal pouch (outpocketing of 4th pouch which gives rise to C cells)


What are the two types of thyroid abnormalities caused by abnormal development?

  • Thyroglossal cysts and fistulae
    • A cyst is caused by isolated patency (thyroglossal cyst will follow the path of descent of thryoid)
    • fistula caused if there is a connection to the foramen cecum 
  • Ectopic thyroid tissue
    • Isolated bits of tissue found at any point along the descent of the thyroid 


What is 1st arch syndrome?

  • Spectrum of defects in development of the eyes, ears, mandible and palate
  • Thought to result from failure of colonisation of 1st pharyngeal arch with neural crest cells 


What is treacher-collins syndrome?

  • Characterised by hypoplasia (lack of development) of the mandible and facial bones 
  • Inherited, autosomnal dominant condition 


What are pharyngeal arches again m8?

  • Out-pocketings of the primitive gut tube in the pharynx
  • 4 pouches which give rise to glanduar structures in the head and neck 
  • Some of the pouch derivatives undergo extensive migration from the poin of origin


What is Di-george syndrome?

  • Congenital thymic aplasia and absence of parathyroid glands 
  • Has a variety of defects: CATCH22
    • 22- deletion on chromosome 22
    • C-cardiac defects
    • A-abnormal facies (facial expressions)
    • T-thymic hypoplasia
    • C-cleft palate 
    • H- hypocalcaemia 
  • due to abnormal development of neural crest 


what is CHARGE syndrome?

  • CHD7 expression is essential for the production of multipotent neural crest
    • C-coloboma (this is what madeline McCann has, caused by hole in a structure of the eye e.g. iris) 
    • H-heart defects
    • A-choanal atresia
    • R- growth and development retardation 
    • G-genital hypoplasia
    • E-ear defect 


Describe the location of the thyroid gland. What do its two lateral lobes and the isthmus cover?

  • In anterior triangle of the neck, below and lateral to the thyroid cartilage 
  • Lateral lobes cover:
    • Anterolateral surfaces of trachea
    • Cricoid cartilage 
    • Lower part of thyroid cartilage 
  • Isthmus crosses:
    • anterior surfaces of 2nd and 3rd tracheal cartilages 


what layer of fasica is the thyroid covered in? what else is in there with it?

  • Pre-tracheal layer 
    • In visceral compartment:
      • Oesophagus 
      • Trachea
      • Pharynx 


Which muscles does the thyroid lie deep to?

  • Sternohyoid 
  • Sternothyroid 
  • Omohyoid


Is the thyroid normally palpable?

Not unless enlarged (goitre)


what are important anatomical relations to consider in thyroidectomy? 

  • trachea 
  • Parathyroid 
  • recurrent laryngeal nerves 


Which two arteries supply the thyroid?

The superior thyroid artery and the inferior thyroid artery 


what is the superior thyroid artery a branch of? where does it pass?

  • 1st branch of external carotid 
  • Passes along lateral margin of thyrohyoid then splits at superior pole of lateral lobe to give anterior and posterior branches 
    • Anterior branch- passes along superior border of thyroid and anastamoses with its twin from opposite side
    • Posterior glandular branch- passes to posterior side of gland and may anastamose  with inferior thyroid artery 


what is the inferior thyroid artery a branch of? where does it pass?

  • Branch of thyrocervical trunk (which is a branch of subclavian)
  • Ascends along medial edge of anterior scalene muscles, passes posteriorly to carotid sheath and reaches inferior pole of lateral lobe where it divides:
    • Inferior branch- supplies lower part and anastamoses with posterior branch of supeiror thyroid artery 
    • Ascending branch: supplies parathyroid 


Describe the venous drainage of the thyroid gland?

  • Superior thyroid vein
    • Drains all areas supplied by superior thyroid artery 
  • Middle and inferior thyroid vein
    • Drains the rest of the thyroid gland
  • Superior and middle drain into the internal jugular vein
  • Inferior drains into the right and left brachiocephalic



Describe the lymphatic drainage of the trachea

  • To nodes beside the trachea and to the deep cervical (jugulo-omohyoid)


After passing through the tracheoesophageal groove what happens to the recurrent laryngeal nerve?

  • They pass deep to posteromedial surface of lateral lobes of thyroid gland and enter thelarynx by passing deep to the lower margin of the inferior constrictor of the pharynx 


Where are the hyoid muscles found?

  • Anterior triangle of the neck 
  • They either arise from or insert into the hyoid 



What are oestrogen mediated changes occuring in the cervix and pelvis in advancing pregnancy that will facilitate birth?

Cervical softening and relaxation of pelvic ligaments


What postural effect can softening of ligamnets in pregnancy due to oestrogen and relaxin have?

Can cause lordosis. Due to relaxation of vertebral ligaments and the additional weight of the foetus 


What landmark gives an estimate for 20 weeks gestation?

Mother's umbilicus


What foetal landmark is used to asses the foetal head position in the birth canal?

The foetal fontanelles 


What foetal strucutre might be at risk during delivery of the shoulders?

Brachial plexus 


If an epidural is used for pain relief, what spinal segments are blocked?



Why is a patient with an epidural at risk of hypotension?

Lumbar sympathetic outflow blockade prevents vasoconstriction 


What is post-partum haemorrhage? What is the most common cause?

  • Blood loss of more than 500ml after vaginal delivery 
  • Uterine atony is the most common cause (uterus fails to contract after delivery)


If the uterus is firm on palpation with continuous bleeding, what other cuase should you consider?

Laceration or trauma to the genital tract or retained placenta 


what is Sheehan's syndrome?

  • Complication of post-partum haemorrhage
  • It is pituitary failure as a result of necrosis of the anterior pituitary gland
  • Thrombosis of blood vessels supplying anterior lobe secondary to severe haemorrhage, leads to necrosis of the anterior pituiary gland which increases in size in pregnancy so increasing its susceptibility to necrosis 
  • The posterior pituitary is unaffected as it has a relatively rich blood supply 


What systolic arterial pressure is seen in hypovolaemic shock? What are the symptoms/signs?

  • <90mmHg 
  • Narrowing of pulse pressure 
  • Feeling faint when sitting or standing 
  • Cold, moist, clammy skin 
  • Rapid, weak pulse 
  • Oliguria