9-12 Questions

How do the effects of interrupted blood flow to the brain differ after 30 seconds, 1-2 minutes, and 5 minutes?

30 seconds: alters a person's brain metabolism 1-2 minutes: neural function may be lost 5+ minutes - lack of oxygen can result in cerebral infarction

What is adenoiditis and why can it result in otitis media?

Adenoiditis is caused by inflammation of the pharyngeal tonsils (adenoids). It can result in otitis media if the infection spreads from the nasopharynx to the middle ear via the pharyngotympanic tube

Where does obstruction of CSF usually occur during obstructive hydrocephalus and why do the calvaria expand?

Blockage usually occurs at the cerebral aqueduct, which runs between the third and 4th ventricles, or in an interventricular foramen. The narrowing of the aqueduct can occur from a tumor nearby in the midbrain or from cellular debris after intraventricular hemorrhage or bacterial and fungal infections of the central nervous system. Ventricles expand above the blockage point and squeezes the brain between centricular fluid and calvarial bones, which is why the calvaria expands

What is a "blowout" fracture of the orbit?

Blowout fracture: indirect traumatic injury displacing orbital walls. Orbital fractures create intra-orbital bleeding, exerting pressure on eyeballs, and making eyeballs protrude (exophthalmos)

How do the levator palatine and tensor palatine muscles contribute to auditory tube function?

By allowing air to enter and leave tympanic cavity, this tube balances pressure on both sides of the membrane. The levator palatine contracts longitudinally, pushing against one wall of the cartilaginous part of the tube, while the tensor veli palatini pulls on the other side of the wall of the tube, thereby actively opening up the tube.

How are conductive and sensorineuronal hearing losses distinguished?

Conductive hearing loss: from external or middle ear. When the individual speaks softly, their own voice sounds loud. Sensorineuronal hearing loss: from defects of cochlea, cochlear nerve, brainstem, or cortical connections

Which muscles reflexively contract to close the laryngeal inlet? What is the stimulus for the reflexive contraction and when is the reflex diminished?

Contraction of lateral cricoarytenoids, transverse and oblique arytenoids, and aryepiglottic muscles close the laryngeal outlet. Stimulus is presence of liquid or particles approaching (as in swallowing) or within the laryngeal vestibule. Diminishes only after loss of consciousness.

During extraction of a 3rd molar, what nerve is susceptible to injury, and which nerves are susceptible to injury during extraction of an unerupted 3rd molar?

During extraction of a 3rd molar--> lingual nerve (closely related to the medial aspect of the 3rd molar) During extraction of unerupted 3rd molar--> alveolar nerves (superior alveolar nerve for maxillary 3rd molar, inferior alveolar nerve for mandibular 3rd molar)

Why is an exogenous airway inserted into a patient under general anesthesia?

During general anesthesia, total relaxation of the genioglossus muscles occurs. When this muscle is paralyzed, the tongue has a tendency to fall posteriorly and obstruct the airway, presenting the risk of suffocation. Therefore, an exogenous airway is inserted in an anesthesized person to prevent the tongue from prolapsing

Why can facial infections spread to the cavernous sinus or to the pterygoid venous plexus?

Facial vein connects with the cavernous sinus through the superior ophthalmic vein Facial vein connects with the pterygoid venous plexus through the inferior ophthalmic and deep facial veins. If there is an infection on the face, it can spread to the cavernous sinus and pterygoid venous plexus in those ways.

How are the superior oblique and inferior rectus individually tested, and how is functional integrity of the inferior oblique and superior rectus distinguished?

Following movements of the examiner's finger, the pupil is moved in an H-pattern to isolate and test individual extra-ocular muscles and the integrity of their nerves. When the eye is initially abducted by the lateral rectus muscle, only the superior rectus can elevate and only the inferior rectus can depress. So, the patient is asked to abduct the eye and to look up to test the function of the superior rectus, and asked to look down to test the inferior rectus. When the eye is initially adducted by the medial rectus, only the inferior oblique can elevate and only the superior oblique can depress. So, the patient is asked to adduct the eye, then asked to look up to test the function of the inferior oblique, and asked to look down to test the superior oblique.

Why is drooping of the superior eyelid (ptosis) a characteristic symptom of Horner Syndrome?

Horner syndrome interrupts the cervical sympathetic trunk, so there won't be sympathetically stimulated functions on the ipsilateral side of the head. Without the function, the smooth muscle fibers interdigitated with the aponeurosis of the levator palpebrae superioris composing the superior tarsal muscle won't be innervated, so the superior eyelid will droop (ptosis). Basically, the superior tarsal muscle isn't getting sympathetic innervation and won't work, so the eyelid will droop.

Why can removal of a swallowed object lodged in a piriform recess cause loss of sensation in the laryngeal mucosa as far distally as the vocal folds?

If an object pierces the mucous membrane in the piriform fossa, it could injure the internal laryngeal nerve, which conveys sensations from the laryngeal vestible and vocal cords.

What typically causes thrombophlebitis of the cavernous sinus, and which cranial nerves could be affected?

Infections in "danger triangle" (orbit; nasal sinuses; superior face) causes thrombophlebitis of facial vein and spreads to cavernous sinus Inflammation affects abducent nerve as traverses sinus.

What is the clinical sign of unilateral hypoglossal nerve injury?

Injury of the hypoglossal nerve (CN XII) results in paralysis and eventual atrophy of one side of the tongue. Therefore, clinical sign of unilateral hypoglossal nerve injury is when the tongue deviates to the paralyzed side during protrusion because of the action of the unaffected genioglossus muscle on the other side. Ipsilateral paralysis.

What is the typical cause of an ischemic stroke and what is its cardinal symptom? How does hemorrhagic stroke differ from ischemic stroke?

Ischemic stroke: related to impaired cerebral blood flow, generally caused by an embolism in a major cerebral artery. Most common cause of strokes are spontaneous cerebrovascular accidents, like cerebral thrombosts, cerebral hemorrhage, cerebral embolism, and subarachnoid hemorrhage Hemorrhagic stroke: follows rupture of an artery or a saccular aneurysm, a sac-like dilation on a weak part of the arterial wall. Most common is a berry aneurysm occurring in the vessels of or near the cerebral arterial circle and the medium arteries at the base of the brain.

How is myringotomy performed to relieve otitis media and if it is improperly performed, what functional losses can occur?

Myringotomy: incise tympanic membrane posteroinferiorly (avoiding chorda tympani + ossicles) to release pus Large perforations causes middle ear deafness and loss of taste from anterior 2/3 of the tongue. Salivatory stimulation might also be affected, since parasympathetic fibers to the submandibular ganglion are also carried by the chorda tympani.

Where can enlarged jugulodigastric lymph nodes typically be palpated?

Near the angle of the mandible.

How do CN III palsy and CN VI palsy differ?

Oculomotor (III) innervates levator palpebrae superioris and most ocular muscles >> palsy causes droop (eyeball is down and out) and pupil dilation *LR6SO4AO3 Abducent (VI) innervates lateral rectus >> palsy causes adduction, patient unable to abduct pupil

What are the causes and symptoms of otitis media?

Otitis media: middle ear infection Earache, bulging red tympanic membrane (inflammation, pus, fluid) Pharyngotympanic tube blocked Often accompanies upper respiratory infections

Where do cranial fractures occur that result in otorrhea and rhinorrhea, respectively? Why do these conditions increase the risk of meningitis?

Otorrhea - leakage from the external acoustic, results from fractures in the floor of the middle cranial fossa Rhinorrhea - leakage from teh nose, results from fractures in the floor of the anterior cranial fossa involving the cribriform plage of the ethmoid bone. Infection could spread to teh meninges from the ear or nose, increasing the risk of meningitis

Why does endothelium line the dural venous sinuses?

Provides antithrombogenic layers, without it we'd have clotting

Which nerves are injured when the pupillary reflex is lost, and which nerves are injured when corneal reflex is lost?

Pupillary light reflex (CN III constricts pupil): Oculomotor injury if lost. Corneal reflex (blinks in response to touch): CN V1 (or VII facial motor) injury if lost

Why can dural pain be sensed in the mucosae of the nasal cavity, oral cavity, and palate or in the scalp or the skin covering the face and neck?

Referred pain: pain perceived at an area different from the site of the injury The trigeminal nerve and the DRG at C2 and C3 send the brain the message that the dura hurts. Since these nerves cover an area that is different from the dura, that's why it will seem like the pain is coming from the nasal cavity, oral cavity, palate, scalp, or skin covering the skull, face, and neck

What is the most likely unilateral nerve deficit in a patient whose uvula deviates to the left when the soft palate is touched with a cotton swab?

Right CN X

If surgical removal of a maxillary molar leads to infection of the maxillary sinus, what nerve would convey pain from the inflammatory site?

Superior alveolar nerves (branches of maxillary nerves)--> supply both maxillary teeth and mucous membrane of the maxillary sinuses

Why does a weak or hoarse voice result from unilateral recurrent laryngeal nerve injury? Why does bilateral nerve injury cause stridor, and how does injury to the external laryngeal nerve affect the voice?

The inferior laryngeal nerve, the continuation of the recurrent laryngeal nerve, innervates muscles to move the vocal cords, so injuring the recurrent laryngeal nerve could also affect the inferior laryngeal nerve. With unilateral recurrent nerve injury, the voice is poor initially because the paralyzed vocal fold cannot adduct to meet the normal vocal fold. Within weeks, thE contralateral fold crosses the midline when its muscles act to compensate. With bilateral nerve injury, the voice is almost absent because the vocal folds on either side of the larynx are motionless that is slightly narrowly than the usually neutral respiratory position. They can't be adducted for phonate, nor can they be abducted for increased respiration, resulting in strIdor (high pitched, noisy respiration). If the external laryngeal nerve is injured, the cricothyroid muscles won't be innervated and the vocal ligaments wouldn't stretch or tense, resulting in a monotonous voice.

How can an incision in the duct of the submandibular gland result in diminished somatic sensation and taste from the anterior tongue?

The lingual nerve is near the submandibular gland's duct carrying the taste fibers from the chorda tympani nerve. These fibers carry taste from the anterior 2/3 of the tongue back to the geniculate ganglion, so if there is an incision in the duct, there's a chance these fibers could be severed and taste could be diminshed.

Why can a fracture of the pterion be life threatening?

The pterion overlies the frontal branches of the middle meningeal vessels. Breaking the pterion could rupture the frontal branch of the middle meningeal artery or veing crossing the pterion, and the resulting hematoma exerts pressure on the cerebral cortex. An untreated middle meningeal vessel hemorrhage can cause death in a few hours.

Why are the normal anastomoses between the cerebral arteries unable to compensate for obstruction of a cerebral artery?

They are microscopic

Why can exophthalmos result from tumors in the middle cranial fossa?

Tumor in middle cranial fossa traverses the superior orbital fissure to orbital cavity. Tumor erodes thin orbital walls, compresses optic nerve + bulges eyeball

Why can aspirates in the laryngeal vestibule be fatal and in extreme cases, what would permit rapid air entry into the larynx?

When a foreign object enters the larynx vestible the laryngeal muscles spasm, tensing the vocal folds. The rima glottis closes, no air enters the trachea, and the resulting blockage might completely seal off the larynx and choke the person. Asphyxiation occurs, person dies in approximately 5 minutes from lack of oxygen if the obstruction not removed. A cricothyrotomy permits fast entry of air. An incision is made through the skin and cricothyroid ligament.

Why is CSF absorbed into the superior sagittal sinus?

arachnoid granulations are protrusions of the meningeal dura and arachnoid into the lumen of the superior sagittal sinus and CSF is absorbed across the arachnoid granulations into the venous blood of the sinus.

How do muscles of the soft palate and pharynx contribute to the three serial stages of swallowing?

stage 1: voluntary, bolus pushed from mouth into the oropharynx by muscles of the tongue and soft palate stage 2: involuntary, soft palate elevated to seal the nasopharynx from the oropharynx and laryngopharynx. Pharynx widens and shorts to receive bolus, suprahyoid muscles and longitudinal pharyngeal muscles contract to elevate the larynx stage 3: involuntary, all three pharyngeal constrictor muscles contract to create peristaltic action to force food into the esophagus