S&F Part II

Question 1

What is thoracic outlet syndrome?

Answer 1

Brachial plexus and subclavian artery run in between middle and anterior scalene and can be compressed

symptoms: tingling, numbness, restricted blood flow
causes: cervical rib, scalene compressing, clavicle compressing, etc.

Question 2

Where is the retropharyngeal space and what is the significance?

Answer 2

Lies between prevertebral fascia and the buccopharyngeal fascia (posterior border of the pretracheal fascia)
extends from neck into chest and can facilitate the spread of infectious pus

Question 3

What are the cervical nerves in the head and neck?

Answer 3

1) Spinal nerves
dorsal rami
ventral rami
-cervical plexus (C1-C4) –> ansa cervicalis portion is motor infrahyoid muscles (depress hyoid bone and larynx- they contract so suprahyoids can move tongue and open jaw), sensation in the neck
-phrenic nerve (C3-C5) –> innervate diaphragm for breathing, runs superficial to anterior scalene
-brachial plexus (C5-C8)
2) Cranial nerves
IX- Glossopharyngeal
X- Vagus (between and deep to common carotid artery and inferior jugular vein in the carotid sheath)
XI- Accessory
XII- Hypoglossal (runs laterally in suprahyoid space)
3) Sympathetic trunk
Superior C1-C4- contains all the postganglionic cell bodies for sympathetic neurons to the head
Middle C5-C6
Stellate C7-T1
*all preganglionic cell bodies in T1 lateral horn; distributed to head on blood vessels

Question 4

What is the pharyngeal apparatus and what are the components?

Answer 4

Days 22-23 - pharyngeal arch development begins just before rostral neopore closes
Pharyngeal arch- pairs of lateral mesenchymal swellings that grow towards ventral midline where they fuse
ectoderm on outside as well as cleft, endoderm and pouch on inside, mesenchyme core
5 Pairs: 1, 2, 3, 4, 6
Each arch has:
-nerve
-artery
-cartilage
-mesenchyme (mesoderm invaded by neural crest cells- can form bone or cartilage)

Question 5

What is the relationship between the pharyngeal arches and cranial nerves?

Answer 5

1- V, trigeminal 
2- VII, facial 
3- IX- glossopharyngeal 
4- X, vagus (superior laryngeal) 
6- X, vagus (recurrent laryngeal) 
*5, 7, 9, 10 are all the mixed sensory + motor cranial nerves

Question 6

What is the relationship between the pharyngeal arches and aortic arches?

Answer 6

aortic arches follow pharyngeal arches (e.g. 1st aortic arch to 1st pharyngeal arch)
exception: 6th aortic arch
LHS: 6th arch retained, and recurrent laryngeal nerve hooks under 6th arch derivative- ductus arteriosus (which becomes ligamentum arteriosium) and ascends back up into the neck to go to larynx
RHS: 6th arch degenerates, recurrent laryngeal nerve hooks under 4th arch derivative- subclavian artery and comes back up into neck to go to larynx
*recurrent laryngeal nerves are branches of vagus X, they are called recurrent bc they mhhove in opp direction from the nerve they branch from

Question 7

What is the relationship between the pharyngeal arches and the cartilage?

Answer 7

Cartilage contributes to bones of jaw and larynx
1- maxillary, mandible, malleus, incus
2- stapes, stapedius, styloid process, upper body/lower horn of hyoid
3- lower body/greater horn of hyoid
4- upper portion of thyroid cartilage
6- lower portion of thyroid cartilage + all other larynx cartilages

Question 8

What is the relationship between the pharyngeal arches and muscles?

Answer 8

Muscles come from neural crest cells invading pharyngeal arches, somitomeres, or somites
*somitomeres alone lead to orbital muscles (away from spinal cord)
somites alone lead to muscles near spinal cord
*autonomic ganglia from neural crest, sensory ganglia from neural crest + placodes
1 (somitomeres + arch): muscles of mastication, tensor tympani + tensor palati, mylohyoid + anterior belly digastric
2 (somitomeres + arch): muscles of facial expression, stylohyoid + posterior belly digastric
3 (somitomeres + arch): stylopharyngeus (posterior 1/3 tongue)
4 (somites + arch): cricothyroid muscle
6 (somites + arch): intrinsic muscles of larynx

Question 9

Describe the development of the tongue

Answer 9

1, 2, 3, 4 arches- tongue mesoderm

1, 3, 4- tongue endoderm –> sensory innervation
anterior 2/3: trigeminal (lingual nerve from mandibular V3 division)
posterior 1/3: glossopharyngeal
base of tongue + epiglottis: vagus

2, 3, 4- tongue endoderm –> taste fibers
anterior 2/3: facial (chorda tympani VII)
posterior 1/3: glossopharyngeal
base of tongue + epiglottis: vagus

Question 10

Describe the development of the thyroid gland

Answer 10

• thyroid gland develops on the tongue in the foramen secum (b/w 1 and 2 pharyngeal arches, later separates anterior 2/3 from posterior 1/3 of tongue)
• connected to tongue through thyroglossal duct
• thyroid gland migrates caudally and ventrally, still attached to thyroglossal duct, to below the cricoid cartilage
• duct degenerates over time – if it doesnt you get cysts on ventral midline –> fistula or you get ectopic thyroid tissue (need to ID with X-ray)

Question 11

Discuss the formation of pharyngeal pouches and their derivatives

Answer 11

1st pouch- middle ear + auditory tube (connects middle ear to nasopharynx to stabilize pressure, but closed to prevent infection), also the pouch combines with the cleft to make tympanic membrane
2nd pouch- tonsils
3rd pouch- inferior parathyroid gland + thymus (picked up first by the thyroid gland during migration)
4th pouch- superior parathyroid gland (picked up second by the thyroid gland)

Question 12

Describe the formation of pharyngeal clefts/grooves and their derivatives

Answer 12

1st cleft- external auditory meatus and external ear canal (also combines with endoderm from 1st pharyngeal pouch to make tympanic membrane)
2, 3, 4 clefts- overgrown by the 2nd arch and creates cervical cyst/sinus that goes away
if it doesnt go away– leads to cysts along anterior border of sternocleidomastoid muscle (different location from the midline thyroid cysts)

Question 13

Describe the development of the face

Answer 13

1) 1st pharyngeal arch develops maxillary prominence and mandibular arch inferior to it
plus there is midline frontonasal prominence
all 3 innervated by trigeminal nerve - maxillary, mandibular, and opthalmic divisions of CN V, respectively
2) mandibular arches come together and fuse –> lower jaw (can result in cleft chin if it doesnt fuse fully)
maxillary prominences fuse to the intermaxillary segments of the frontonasal prominence (remnant is philtrum)

Question 14

Describe the development of the palate. How do cleft palates and lips originate?

Answer 14

1) Primary/hard palate- from frontonasal prominence, holds incisors
secondary/soft palate - fusion of palatine shelves (ie lateral palatal processes) from maxillary prominence, fuse to the primary palate
2) originate from failure to fuse
-isolated cleft palate: failure of palatine shelves to fuse
-cleft lip with cleft palate: failure of palatine shelves to fuse, also failure of intermaxillary segment (derivative of frontonasal process) to maxillary prominence to palatine shelf
-cleft lip: intermaxillary segment to maxillary prominence to palatine shelf (can be unilateral or bilateral)
-isolated cleft lip: intermaxillary segment to maxillary prominence

Question 15

Where do sensory, motor, and mixed nerves go?

Answer 15

Sensory- from neural crest cells, neural crest induced by notochord and placode (ectodermal thickening invaded by neural crest cells that become ganglia or neural tissue layers)
Motor- somitomeres
Mixed- pharyngeal arches

Question 16

What are the meninges? What is their relationship at spinal vs cranial levels?

Answer 16

Meninges- pia mater, arachnoid mater, dura mater
arachnoid mater and pia mater have same relationship at spinal and cranial levels - pia mater fused to brain/spinal cord, and arachnoid mater pushed against dura mater by CSF compression
in spinal cord, there is epidural space between dura mater and periosteum
at cranial level- there is no epidural space, dura and periosteum are fused together

Question 17

Describe three sources of intercranial bleeding:

1) epidural hematoma
2) subdural hematoma
3) subarachnoid hematoma

Answer 17

1) branches of middle meningeal artery run between skull bone and periosteal dura
skull trauma –> torn artery –> bleeding –> creates epidural space filled with blood (epidural hematoma)
common site: lateral side near pterion
lucid interval after regaining consciousness while hematoma is forming and increased pressure causes loss of consciousness again
*does not cross suture lines in skull bc dura mater is very tightly bound
2) normally arachnoid is pressed against the dura mater
cortical/bridging veins bring venous blood from veins and penetrate arachnoid and dura to enter the sinus
blow to head –> veins tear right where they flow into sinus –> venous bleeding –> creates subdural space between arachnoid and dura (subdural hematoma)
onset is slower than epidural hematomas (slower leakage of blood from lower pressure veins)
*can cross suture lines in skull, can be caused by CSF leak
3) branches of vertebral and internal carotid arteries are on pia mater –> in subarachnoid space
aneurysm –> arterial rupture –> arterial blood enters subarachnoid space and mixes with CSF

Question 18

Describe the spread of infection from extracranial to intracranial

Answer 18

emissary veins do not have valves so blood can flow into the cranial cavity is pressure gradient is switched –> can spread infection superficially (eg from pimple) into the cranial cavity –> can cause meningitis

Question 19

What is hydrocephalus? Describe non-communicating vs communicating hydrocephalus

Answer 19

1) hydrocephalus- increased CSF resulting in increased CSF pressure
2) non-communicating - CSF obstructed from passing into the subarachnoid space
most common site is cerebral aqueduct - can tell based on which ventricle is enlarged
3) communicating - CSF can get into the subarachnoid space but is not adequately resorbed eg if there is meningeal infection

Question 20

What is a tracheostomy? What is a cricothyrotomy?

Answer 20

Tracheostomy- incise thyroid isthmus and trachea and place tube to help with breathing
Cricothyrotomy- emergency procedure where you incise cricoid membrane bc you know you won’t be affecting your thyroid, but patient could lose voice box

Question 21

What are the components of each of the 3 layers of the eye? What is the blood supply to the eye?

Answer 21

1st Outer- sclera layer (maintains shape) + cornea
2nd Middle- choroid layer, ciliary body (which includes smooth ciliary muscle for accommodation), ciliary processes (secretes aqueous humor), iris (also has smooth muscle to control size of the pupil)
3rd Inner- retina layer (visual receptor cells + nerve cells), fovea in center of macula (greatest concentration of photoreceptor cells for best acuity), optic disk (blind spot where exiting nerve fibers converge)
Only blood supply- central artery of retina, which runs down the center of the optic nerve with the vein (no collateral circulation)

Question 22

What is the pathway of aqueous humor in the eye? What is the clinical correlation?

Answer 22

Ciliary processes–> posterior chamber (bw lens and iris) –> anterior chamber (bw cornea and iris) –> canal of schlemm –> absorbed into venous system
Subpar absorption –> increase in intraocular pressure –> glaucoma

Question 23

Describe process of refraction of light and focusing on the retina

Answer 23

Cornea –> anterior chamber –> pupil –> posterior chamber –> lens –> vitreous body –> retina
Most refraction happens at the cornea
abnormalities in curvature of cornea –> light not focused properly (need LASIK or contact lenses to fix the shape)
-near sighted (cant see things far away)–> light focuses in front of retina
-far sighted (cant see things close by) –> light focuses behind the retina

Question 24

What is the accommodation reflex? What is the clinical correlation

Answer 24

Lens- only variable component for changing focal distances
1) Accommodation - increasing refractive power to see things close by
Ciliary muscle contracts –> makes lens radius smaller –> suspensory ligaments slacken –> allows lens to get thicker and more refractive –> can see objects close by
2) Ciliary muscle relaxes –> lens radius larger –> suspensory ligaments tighten –> lens gets thinner and less refractive –> can see far away objects
3) Presbyopia - due to aging, lens lose elasticity and are not able to thicken as well –> can’t see objects near by –> need reading glasses

Question 25

What is the significance of having anastomosis between internal carotid artery and external carotid artery near the supraorbital foramen?

Answer 25

Normally flow is from internal –> external carotid
BUT if you have occlusion of internal carotid –> flow through ophthalmic and supraorbital arteries reduced –> flow switches
can use doppler ultrasound transducer to look at direction of flow and tell whether there is occlusion of internal carotid pathway

Question 26

What is the difference between carotid body and sinus?

Answer 26

Carotid body- chemoreceptors to monitor O2 content, located near bifurcation of common carotid artery
Carotid sinus- baroreceptors to monitor pressure (sympathetic), dilation of internal carotid artery
both innervated by CN IX (glossopharyngeal)

Question 27

Where is the sympathetic trunk located?

Answer 27

In retropharyngeal space (bordered by anterior side of prevertebral fascia + buccopharyngeal fascia)
it lies deep and medial to the carotid sheath

Question 28

Why are vocal cords paralyzed post op with tracheostomy?

Answer 28

Bc the recurrent laryngeal nerve runs between the trachea and esophagus and is in danger when thyroid is accessed

Question 29

What are the boundaries of the infratemporal fossa?

Answer 29

Lateral: Ramus of mandible
Medial: Lateral pterygoid plate of sphenoid bone
Anterior medial: maxilla/buccinator/superior constrictor of pharynx
Posterior: tympanic plate of temporal bone, styloid process

Question 30

Describe the temporomandibular joint.
Describe the actions when the mouth is opened.
What are the types of TMJ dislocation?

Answer 30

1) modified hinge synovial joint that connects mandible to temporal bones, surrounded by capsule
two joint cavities separated by disk
upper cavity: protrusion/retrusion of the jaw, sliding/gliding ie translation
lower cavity: elevation/depression of the mandible
*disk and condyle move together
2) Mouth opened - disk + condyle translates anteriorly in upper compartment
lower compartment - hinge motion to depress the mandible
3) Occurs when disk + condyle cross too anteriorly
unilateral- jaw deviates to unaffected side, could be fracture/cervical spine injury
bilateral- more common, cannot close mouth
Need to physically force jaw back into place

Question 31

Describe the vasculature of the infratemporal fossa (arteries + veins)

Answer 31

1) Arteries- External Carotid artery branches
-superficial temporal
-maxillary –> infraorbital
–> mandibular portion
——-> inferior alveolar (mandibular teeth in lower jaw) –> mental artery (mental foramen)
——-> middle meningeal (cranial meninges)
2) Veins - pterygoid venous plexus
connects facial vein and external jugular vein and cavernous sinus via emissary veins
how infection can spread from superficial to deep

Question 32

Describe the innervation of the infratemporal fossa

Answer 32

Mandibular division of trigeminal (V3)

1) Anterior division
- muscular- motor to muscles of mastication
- buccal- sensory to inside of cheek
2) Posterior division
- lingual- sensory anterior 2/3 tongue
- inferior alveolar- sensory to lower jaw teeth + chin, motor to mylohyoid/anterior belly of digastric
- auriculotemporal- sensory to TMJ and scalp (splits so middle meningeal artery can pass through foramen spinosum en route to skull)

Question 33

What are the muscles for the infratemporal fossa, their actions, and their innervation?

Answer 33

All muscles of mastication innervated by V3 (muscular branch)
-Temporalis- elevation of mandible (closing mouth), retrusion
-Masseter- close mouth and protrusion of mandible
-lateral pterygoid- unilateral- move chin to opp side, bilateral - protrusion and open mouth
-medial pterygoid- unilateral - move chin to opp side
bilateral- protrusion and close mouth
*mylohyoid and anterior belly digastric also open mouth

Question 34

What is the structure and function of the inner ear

Answer 34

1) 3 semicircular canals - rotatory movement
2) utricle- detects horizontal movement through vestibular hair cells
3) saccule- detects vertical movement through vestibular hair cells
4) cochlea- coiled structure, inside is duct filled with endolymph, with hair cells to detect vibrations of different frequencies, surrounded by perilymph
vibration of footplate at middle ear carried through perilymph –> vibration at hair cells –> neural impulse carried by vestibular division of CN VIII vestibulocochlear
*loss of hair cells –> hearing loss

Question 35

What is the structure and function of the outer ear

Answer 35

1) Pinna - funnel to collect sound waves
2) External ear canal - cartilage outside, bone inside
skin contains glands that secrete cerumen (Ear wax)
3) tympanic membrane/eardrum- separates external ear from middle ear, formed from ectoderm of 1st pharyngeal cleft + endoderm from 1st pharyngeal pouch
most innervation from V3

Question 36

What is the structure and function of the middle ear

Answer 36

1) Ossicles connected by synovial joints- Malleus (connected to tympanic membrane), Incus, Stapes (footplate of stapes sits in oval window of the inner ear)- transmit and amplify vibrations to the inner ear
amplifies 30 Db to compensate for 30 db loss of energy at air/water interface
2) Tensor tympani- contracts –> tenses tympanic membrane –> reduces amplitude of vibration –> reduces perceived loudness
innervated by V3 (1st pharyngeal arch)
3) Stapedius - contracts –> tenses the stapes –> reduces perceived loudness *much more effective than tensor tympani
innervated by VII (2nd pharyngeal arch)

Question 37

Explain the function of the connection between the middle ear and nasopharynx

Answer 37

Connection = Eustacian tube
function = equilibrate pressure bw middle ear cavity and environment
most of the time its closed to prevent infections, we open it by swallowing etc when there is pressure differential eg on a plane
in children the tube is open –> more frequent ear infections

Question 38

What are the two types of hearing loss and how can they be tested?

Answer 38

1) Conductive - external/middle ear issue eg cerumen buildup, ruptured eardrum, ostosclreosis
2) Sensorineural- inner ear or CNS eg aging, hair cell damage, CN VIII
3) Weber test- tuning fork placed on the skull midline to bypass external/middle ear
both inner ears normal - hear sound from midline
sensorineural - hear sound from the normal side
conductive - hear sound from affected side
Weber cant tell you which type you have
4) Rinne test- for conductive hearing loss
bone conduction first, when sound is no longer heard then air conduction at external ear, and patient should be able to hear sound again bc of amplification
normal: AC > BC

Question 39

Explain the characteristics and function of the following:

1) Lymphocyte
2) Monocyte
3) Neutrophil
4) Eosinophil
5) Basophil
6) Megakaryocyte
7) Platelets

Answer 39

1) Lymphocyte:
agranulocyte
circulates in blood
mostly nucleus, little larger than RBC
function- immune response (B, T, NK cell) - immunocyte (everything else is phagocyte)
2) Monocyte:
agranulocyte
largest white blood cell
horseshoe nucleus
function: presents antigen, produces CSF for blood cell formation in marrow, precursor to macrophage + osteoclasts + dendritic cells
3) Neutrophil
granulocyte
multilobed nucleus (3-5) w/ barr body, pinkish cytoplasm
function: phagocytosis, first responder at infection
4) Eosinophil
granulocyte
2-3 lobed nucleus, red-orange granules in cytoplasm
function: phagocytosis in parasitic infections, reduce inflammation
5) Basophil
granulocyte , v rare
2 lobed nucleus, large purple granules; look like mast cells but are in the blood
function: allergic response
6) Megakaryocyte
largest cell in bone marrow
single nuclei that looks like brain
function: make platelets
7) Platelets
tiny, fragments of megakaryocytes
function: clotting
*review EM of platelets and megakaryocytes for exam

Question 40

What % of blood is red blood cells? What % is white blood cells? Where do they operate

Answer 40

45% RBC -function inside cardiovascular system, biconcave
1% WBC - function outside the circulatory system, migrate out of blood vessels through diapedesis
55% plasma

Question 41

What are the functions, major features and boundaries of the oral cavity and its sensory innervation?

Answer 41

1) Function
proximal site digestion
salivary glands to moisten
tongue for taste and bolus
2) Boundaries:
superior - palate (hard and soft)
inferior- tongue/floor of mouth
posterior- oropharynx
3) Sensory innervation- salivary glands (innervated by parasympathetic, shut down by sympathetic)
Parotid- preganglionic in lesser petrosal nerve (IX), postganglionic in otic ganglion, rides on auriculotemporal nerve V3 (20% saliva)
Submandibular/sublingual- preganglionic in chorda tympani (VII), postganglionic in submandibular ganglion, rides on lingual nerve V3 (80% saliva)

Question 42

What are the functional anatomy, muscles, innervation, and blood supply to the tongue?

What is the relation of structures to the hyoglossus muscle?

Answer 42

1) Functional anatomy
sulcus terminalis which runs from foramen secum and divides tongue into 2 parts
epiglottic velleculae- depression behind tongue root, landmark for intubation
2) Muscles- Tongue is Twelve
Palatoglossus (X)- elevates tongue to close oropharynx
Styloglossus (XII)- elevate/retract tongue
Hyoglossus (XII)- flatten/retract tongue
Genioglossus (XII)- stick out tongue; *LESION - tongue deviates towards affected side
Intrinsics (XII)- shape bolus
3) Innervation
posterior 1/3 - taste + sensory = IX glossopharyngeal
anterior 1/3 - sensory = lingual (V3) and taste = chorda tympani (VII)
4) Blood supply
Lingual artery - goes medial to hyoglossus muscle

medial to hyoglossus: lingual artery, glossopharyngeal IX
lateral to hyoglossus: lingual nerve V3, hypoglossal XII, submandibular duct

Question 43

What are the muscles of the pharyngeal walls and soft palate + functions + innervation

Answer 43

3 outer circular (X): move food bolus
-superior constrictor
-middle constrictor (attaches to hyoid)
-inferior constrictor (attaches to thyroid/cricoid cartilages)
3 inner longitudinal: elevate pharynx
-stylopharyngeus (IX bc glossopharyngeal runs deep to it en route to the tongue)
-salpingopharyngeus (X)
-palatopharyngeus (X)
2 soft palate muscles
-tensor palati (V3), in nasopharynx
-levator palatini (X), elevates soft palate to prevent food from entering nasopharynx *LESION- uvula deviates towards unaffected side

Question 44

What are the compartments of the pharynx and their boundaries?

Answer 44

1) Nasopharynx - respiratory
- from roof of nasal cavity to soft palate, posterior is superior constrictor muscle
- auditory/Eustachian tube for communication with the middle ear
- adenoids tonsillar tissue
2) Oropharynx - digestive
- from soft palate to epiglottis, posterior is middle constrictor
- uvula, palatoglossal arch (anterolateral), tonsils (middle), palatopharyngeal arch (posteromedial), + IX glossopharyngeal nerve
3) Laryngopharynx - digestive
- from epiglottis to esophagus, posterior is inferior constrictor
- piriform recess on lateral sides where food and fluid travels, while epiglottis (flap of cartilage) covers larynx/windpipe in the midline

Question 45

Describe the mechanics of deglutition

Answer 45

1) Voluntary
- muscles of mastication chew food (V3- anterior mandibular)
- lips pursed + buccinator keeps food in place (VII- buccal branch)
- saliva produced by parotid (IX) and submandibular/ sublingual glands (VII)
- tongue tastes food (VII- chorda tympani on anterior), (IX on posterior 1/3)
- tongue senses food (V3- lingual for anterior), (IX for posterior 1/3)
- intrinsic tongue muscles form bolus (XII)
- palate senses (V2) and tastes (VII- greater petrosal)
2) Involuntary
- sealing nasopharynx with tensor palati (V3) and levator palati (X)
- seal oropharynx with palatoglossus (X)
- seal laryngopharynx by elevating hyoid bone with suprahyoids - (VII- post belly + stylo) (V- ant belly + mylo) and elevating pharynx (X- salping + palato) (IX- stylo)
- epiglottis covers larynx (XII)
- activate constrictor muscles (X)

Question 46

What is the significance of:
C3
C4
C6

Answer 46

C3- hyoid bone
C4- start of thryoid cartilage, bifurcation of the common carotid artery
C6- cricoid cartilage

Question 47

Describe the laryngeal cartilages and membranes

Answer 47

thyroid cartilage
cricoid cartilage
arytenoid cartilage - sits on posterior cricoid
vocal ligament (true vocal fold)- from vocal process of arytenoid to thyroid cartilage
cricothyroid ligament (conus elasticus) - connects cricoid and thyroid cartilages
quadrangular membrane - connects epiglottis to arytenoid, inferior edge is vestibular ligament (false vocal fold)

Question 48

What is the rima glottidis? How is its shape affected by the movement of the vocal chords? What are those muscles innervated by?

Answer 48

1) Rima glottidis- space between the vocal folds/chords
wide when respirating, very thin when phonating
2) posterior cricoarytenoid muscles abduct
lateral cricoarytenoid muscles adduct
cricothyroid and vocalis muscles tense the vocal folds
3) Innervation - all X vagus
superior laryngeal - branches into internal and external laryngeal
internal laryngeal - sensory through thyrohyoid membrane with superior laryngeal artery (senses presence of food in piriform recess)
external laryngeal - motor to cricothyroid (can be damaged with superior thyroid artery ligation)
recurrent and inferior laryngeals - sensory below vocal fold, motor to other intrinsic laryngeal muscles

Question 49

Nasal cavity: functions, innervation, blood supply

Answer 49

1) Function:
-Respiratory: filter, humidify, warm air + 3 turbinate bones create air flow
-Olfactory: epithelium on superior aspect of nasal cavity (where olfactory nerve comes through cribriform)
2) Innervation
Olfactory I
Nasociliary V1 - sensory at front of cavity
Maxillary V2- sensory at posterior
sympathetic- vasoconstriction (reduce mucous)
parasympathetic- controls mucous secretion (via greater petrosal nerve VII)
3) Blood supply
Anterior- facial artery (external carotid) and opthalmic (internal carotid) - anastamosis
Posterior- Maxillary (external carotid) through sphenopalatine artery
*anterior nosebleeds easier to control, posterior harder bc blood spurts and goes down throat, need to pack the cavity

Question 50

What are the paranasal sinuses and their sites of drainage?

Answer 50

1) Frontal- middle meatus via frontonasal duct
2) Ethmoidal- superior and middle meatus via air cells
3) Sphenoidal- sphenoethmoidal recess via ostium
4) Maxillary- middle meatus via ostium
inferior meatus via nasolacrimal duct (where tears drain)
*fluid passes into nasopharynx and is swallowed

Question 51

What is the mechanism behind brain freeze?

Answer 51

Sudden cold on roof of the mouth - blood vessels vasoconstrict then vasodilate to warm up oral cavity –> irritate nerves in the area eg palatine nerve
referred pain - since palatine nerve goes to trigeminal ganglion, feel pain in supraorbital and infraorbital

Question 52

Describe the cranial nerve test

Answer 52

I- Olfactory; test one nostril at time with odorous substance eg coffee
II- Optic; Visual acuity (snellen eye chart), visual field (wiggling fingers- rods in periphery good for sensing movement), can see with ophthalmoscope
II and III- pupillary light reflex - need to test both pupils and need II to sense stimulus, need III to constrict pupils (parasympathetic)
III- Oculomotor; if pupils are fixed and dilated –> uncal herniation where increased pressure causes uncus to compress III, convergence (accommodation reflex to make lens thicker )- medial recti to adduct + constrictor pupillae (parasympathetic)
III, IV, VI- ocular movement H test; diplopia caused by strabisumus (medial or lateral)
V- for sensory stroke face in 6 regions, for motor (V3 only) have patient clench teeth and open jaw against resistance (deviates towards side of lesioned lateral pterygoid)
open mouth - if it deviates there is a lesion in opposite lateral pterygoid
VII- test facial muscles eg puff out cheeks, raise eyebrows, wrinkle forehead smile, for sensory test behind ear (posterior auricular nerve), symmetry of nasolabial folds (bell’s palsy)
V and VII- corneal blink reflex - need V to sense stimulus and VII to actually close eyes
VIII- Weber and Rinne tests
IX- sensation from back of tongue
IX and X- gag reflex (IX is sensory, X is motor to elevate the pharynx)
X- say ahh- elevation of soft palate; uvula deviates away from side of lesion due to levator palati
XI- head turn to opposite side, tilt head to same side (sternocleidomastoid), shoulder shrug (traps)
XII- stick out tongue, deviates in direction of lesion due to genioglossus