CLINICAL CORRELATES Flashcards
How does a burst fracture of C1 typically occur? Why does it not necessarily result in spinal cord injury?
Happens when the lateral masses of C1/atlas are squeezed b/w the occipital condyles of the cranial base and C2, because of severe vertical forces
Burst fracture = break in anterior and posterior arches and potential rupture of transverse ligament holding the dens to the facet for dens
No spinal cord injury b/c breaking the arches widens the vertebral foramina
Why are the skin & edges of the platysma carefully sutured during repair of neck wounds?
If it’s not done, the platysma is distracted and stretches the skin in various directions, leaving ugly scars on the skin
Where can infections b/w the investing fascia & muscular part of the pretracheal fascia spread?
Up to the superior margin of the sternal manubrium
Where can infections b/w the investing fascia & visceral part of the pretracheal fascia spread?
Can go into the middle mediastinum anterior to the pericardium
What are symptoms of a retropharyngeal abscess?
Difficulty swallowing (dysphasia) & difficulty speaking (dysarthria) because it will press on the esophagus and the trachea which are located in the visceral part of the pretrachia fascia
What are the common causes & symptoms of congenital torticollis?
Causes: Lesion/fibrous tissue tumor in the SCM
Symptoms: Constant tilting of the head to the ipsilateral side and rotation of face to the contralateral side
What 4 diagnostic signs can be indicated by prominence of the EJV?
This means there is high venous pressure
- blocked SVC
- Heart failure
- Enlarged supraclavicular LN
- Increased intrathoracic pressure
How is backflow into the IJV prevented when intrathoracic pressure is increased or when standing on one’s head?
The inferior portion of the IJV has the INFERIOR BULB OF THE IVJ which contains a bicuspid valve that prevents backflow
Why do cervical sympathetic ganglia not receive white communicating rami?
This is only found from T1-L2 b/c those are the only locations that have a lateral horn
Also, these cervical sympathetics are all postsynaptic sympathetics while the thoracic and lumbars are presynaptic and thus have white communicating rami
How do postsynaptic sympathetic fivers from the cervical ganglia reach the cervical spinal nerves, the thoracic viscera, viscera of head & neck, and the intracranial cavity?
Cervical spinal nerves: Gray rami communicans
Thoracic viscera: cardiopulmonary splanchnic nerves
Viscera of head/neck + intracranial cavity: cephalic arterial branches
Why do ipsilateral vasodilation & anhydrosis in the face and neck occur after unilateral sympathetic trunk injury?
Sympathetics are needed for constriction of most things
w/ the damage you have unopposed parasympathetics and this means that you have vasodilation and excessive sweating (anhydrosis) from unregulated sweat glands
HORNER’S SYNDROME!
How do thyroglossal duct cysts develop? Where are they typically located?
Cysts form from remnants of the thyroglossal duct that has not been cleared away
Found all along the path of descent for the thyroid gland but specifically IN THE ANTERIOR PORTION OF THE NECK, CLOSE OR JUST INFERIOR TO THE BODY OF THE HYOID BONE
Where is aberrant thyroid glandular tissue typically located?
- Anywhere along the path of the thyroglossal duct
- Root of the tongue (posterior to the foramen cecum)
- Next to or just inferior to the body of the hyoid bone
Why are the inferior parathyroids susceptible to ectopic location in the thymus?
Both are derived embryonically from the endodermal 3rd pharyngeal pouch and they travel down together
What are lateral cervical cysts?
These are remnants of the cervical sinus that can be found below the angle of the jaw
How are lateral cervical cysts & thyroglossal cysts distinguished during physical examinations? How are the thryoglossal cysts & cancerous thyroid nodules distinguished?
Lateral cervical cysts = below the angle of the mandible
Thyroglossal cysts = often next to or inferior to the hyoid bone of anterior neck
Cancerous thyroid nodules = inferolateral to the thyroglossal cysts around the 2nd and 3rd laryngeal cartilage rings
What is goiter? Why does hypertrophy of follicular epithelium occur w/ graves disease?
Goiter is just an enlargement of the thyroid gland and can be due to many different diseases
Grave’s Disease = type of autoimmune where antibodies bind to the TSH receptors on follicular cells of the thyroid and chornically overstimulate —> LEADS TO HYPERTROPHY
What is the usual cause of primary hyperparathyroidism? Why do kidney stones result?
Primary cause = adenoma of one or more parathyroid glands
Kidney stones occur b/c the parathyroid secretes calcitonin to increase blood calcium levels by increasing osteoclastic activities…thus more calcium in blood = more calcium in filtrate and more calcium being reabsorbed —> FORMS kidney stones!
Why can thyroidectomy be fatal?
The parathyroid glands are found on the posterior end of the thyroid gland…if you undergo this procedure, then you can potentially remove the parathyroid hormone
Thus you’ll have low blood calcium = TETANY (a neurological syndrome where you have muscle spasms and twicthing)
Tetany of your respiratory and laryngeal muscles can be fatal
What are the functions of sutures & fontanelles? What is the value of postnatal palpation of the anterior fontanelle?
Function: help bones to overlap so that head can be squeezed through at birth and then after, allows the head to grow as big as needed
Postnatal palpation –> done to check if the cranial bones are ossifying correctly & to check for intracranial pressure
How is brain development affected by premature closing of the sutures and fontanelles and ensuing cranial malformations?
IT’S NOT AFFECTED!
Why do infants have large calvaria & rudimentary development of the face?
The calvaria or skull cap undergoes precocious development that makes it bigger than the face and also makes the face look smaller than it actually is
Why is the loose connective layer the “danger are of the scalp”?
The loose connective tissue allows for pus or bacteria or blood to spread easily
Via small emissary veins can spread into the cranial cavity and reach structures like the meninges
Which peripheral branch of the trigeminal ganglion is most commonly affected by neuralgia?
Maxillary nerve (CN V2), then mandibular (CN V3), and finally ophthalmic (CN V1)
When are infraorbital nerve blocks employed? What is the probable consequence of a careless injection?
These are used when you are treating wounds in the upper lip or cheek or repairing incisors of the maxilla
If you mess up, can enter the orbit and thus temporarily paralyze the extraocular muscles
What is an ophthalmic herpes zoster? Symptoms?
A viral infection that creates lesions along the ophthalmic nerve (CN V1) and leads to the formation of vesicles along the entire path of the nerve
Symptoms: Corneal ulceration &/or corneal scarring
Why is the facial nerve susceptible to injury during forceps delivery of a newborn?
In newborns the mastoid process of the temporal bone is yet to be fully developed. Thus the facial nerve isn’t protected and can be easily damaged by the location of the forceps around the skull if too close to the stylomastoid foramen
Why do patient’s with Bell’s Palsy frequently dab the affected eye & corner of the mouth & have difficulty chewing & speaking?
In Bell’s Palsy you have damage to the facial nerve (CN VII) and can lead to paralysis of the facial nerves
Dabbing corner of affected eye = orbicularis occuli…loss of tonus causes the inferior eyelid to evert and lacrimal fluid isn’t spread around evenly and can be drained improperly
Dabbing corner of mouth = orbicularis oris + buccinator can let food collect in oral vestibule
Difficulty chewing & speaking= weak muscles of the lips makes this difficult to do
What is the most common nontraumatic cause of facial nerve palsy? When is recovery from facial paralysis remote?
Inflammation of the facial nerve as it passes through the stylomastoid forament
Recovery is remote if the nerve is sectioned or severed
Why can scalp lacerations be fatal?
You have a lot of anastomoses here and thus the arteries and vessels can bleed from both ends
Where is pressure best applied to stop bleeding from lip lacerations?
On both sides of the face near the angle of the mandible to cut off the supply form the facial arteries
What is the principle cause of squamous carcinoma of the lip? Which lip is usually involved? When does metastasis occur to the submental or the submandibular lymph nodes?
Cause = too much UV radiation from sunshine
Lower lip is usually more involved
Submental= central part of the lower lip, floor of the mouth, & apex of the tongue
submandibular= lateral portions of the lower lip
Why is the facial nerve susceptible to injury during parotidectomy?
The facial nerve after exiting the stylomastoid foramen goes directly to the parotid plexus located over the parotid gland
Thus it can be affected
Why does TMJ dislocation typically occur anteriorly rather than posteriorly? Which nerves are most susceptible to injury?
Posterior is reinforced by the postglenoid tubercle & the strong intrinsic lateral ligament
Nerves: Branches of auriculotemporal nerve
Why does the mouth fall open when sleeping?
The loss of tonic contraction of the mandible allow for gravity to cause depression
Where is the injection site for a mandibular nerve block? What regions are affected?
Site: Through the mandibular notch into the infratemporal fossa where the mandibular nerve enters
Regions: Scalp superior to the ear, lateral cheek, chin and below, teeth, lower lip, TMJ, & external ear
Why can pain from parotidis extend to the TMJ, ear, & scalp superior to the ear?
Referred pain from the somatic sensory fibers of the auriculotemporal nerve that brings visceral motor innervation to the parotid glands
How can severe infections of the ethmoidal cells cause blindness?
If the ethmoidal sinuses are blocked and don’t drain, then it can rupture through the thin walls of the orbit and affect the eye
Also, some posterior ethmoidal cells are found on the optic canal and thus they can affect the optic nerve and opthalmic artery when they have severe infections
Why do sinus infections most commonly occur in the maxillary sinuses? How are they cannulated for draining?
Maxillary sinus = holes are super small and found on the superomedial walls. Thus they don’t drain until they are full and the holes are easily obstructed. This provides a perfect breeding ground for bacterial proliferation.
Go from the nostril to the maxillary sinus via maxillary ostium/opening
Why is epistaxis relatively common?
Nosebleeds occur often due to the rich blood supply to the nasal mucosa
How can anosmia & rhinorrhea serve as a clue to a fracture of the cranial base?
Anosmia = loss of sense of smell Rhinorrhea = CSF leaking from nose
W/ a fracture of the cranial base you can potentially damage the cribriform plate of the ethmoid bone and thus rip the olfactory cells from the olfactory bulb that they synapse w/
Rhinorrhea b/c your CSF is found in the subarachnoid space and shouldn’t be in the nose unless it has leaked through a crack
What is the dividing landmark b/w anterior & posterior cleft palate deformities? How do severities of anterior clefts vary?
Dividing landmark = incisive foramen
Anterior clefts can be barely detectable to the entire extension of the nose
How is the pterygopalatine fossa surgically accessed?
Through the posterior wall of the maxillary sinus, which is also the anterior wall of the pterygopalatine fossa
How do taste buds differ from the olfactory mucosa?
olfactory mucosa = bipolar neurons that synapse w/ sensory cells in the olfactory bulb after going through the cribriform plate
taste buds = on the endothelium of large papillary cells and they contact afferent nerves from their basillar surface to convey signals
Where would injury of CN VII has occured if its somatic motor fibers were severed but is visceral motor and sensory fibers for taste remain intact?
Near the stylomastoid foramen
Where would injury of CN VII occur if all the functions were lost?
Near it’s originating point in the pons of the posterior cranial fossa or just before the geniculate ganglion/proximal to the origin of the greater petrosal nerve
Why is an exogenous airway inserted into a patient under general anesthesia?
When you’re anesthesized, your tongue falls backward and can potentially block off the airway
Due to complete relaxation of the genioglossus muscle
What is the clinical sign of unilateral hypoglossal nerve injury?
Tell them to protrude the tongue and whichever side it points to is the side of the lesion or injury
What is the most likely unilateral nerve deficit in a patient whose uvula deviates to the left during swallowing?
Uvula deviates contralateral to the side of injury
So this person has a right vagus nerve defect that affects the right musculus uvulae from pulling the uvula upwards
What are they symptoms of the palatine tonsillitis? When is tonsillectomy advised?
Symptoms: Sore throat & fever and usually accompanies pharyngitis
Not advised unless it blocks ability to swallow and breath
What is adenoiditis? Why can it necessitate mouth breathing? How can adenoids result in otitis media?
Adenoiditis is inflammation of the adenoid/pharyngeal tonsils
You get mouth breathing b/c the tonsils (in pharyngeal recess) can prevent air from the nasopharynx from enter the oropharynx
Otitis media can happen in the infection spreads from adenoids into the auditory (Pharyngotympanic) tube which is located anterior and inferior to the adenoids
What are the afferent & efferent limbs of the gag reflex?
Afferent = CN IX Efferent = CN X & CN IX
How does elastic cartilage contribute to the epiglottic function during swallowing?
It lets the epiglottis bend backward to cover the glottis or the space b/w the two vocal ligaments
How can removal of a swallowed object lodged in a piriform recess lead to the loss of sensation in the mucosa of the laryngeal vestibule?
It can potentially damage the internal laryngeal nerve (branch of the superior laryngeal nerve)
How does the heimlich maneuver remove foreign bodies aspirated into the laryngeal vestibule? Why can aspiration be fatal? In extreme cases, what would permit rapid entry of air into the larynx?
Heimlich maneuver - uses any residual air that you have in your lungs to forcefully push through the larynx and push out the obstructive material. Suddenly compressed the diaphragm to rise up and push air out of lungs.
Aspiration can be fatal since the lack of oxygen thanks to the blockage and the uncontrollable spasm of the laryngeal muscles
Insertion of needle through the circothyroid ligament that holds the circoid cartilage and the thyroid cartilage together
Which laryngeal muscles are active during normal respiration, forced respiration, phonation, & whispering?
Normal respiration: Everything is relaxed
Forced respiration: posterior circo-arytenoids
Phonation: Arytenoid muscles & moderate contraction of cico-arytenoid muscles
Whispering: Contract circo-arynthenoids forcefully
Why does weak or hoarse voice result from unilateral recurrent laryngeal nerve injury? Stridor results from bilateral nerve injury? How does injury to the external laryngeal nerve affect the voice?
Unilateral recurrent laryngeal nerve= you can’t move one side of the vocal cords and thus the other side works and tries to compensate by coming to the midline but not enough —> WEAK VOICE
Bilateral recurrent laryngeal nerve= Both sides can’t move their vocal folds which are slightly narrower than resting position —> STRIDOR
Injury to external laryngeal nerve = MONO-TONE b/c you can’t tense vocal cords due to loss of innervation of the circothyroids
What is the most common symptom of esophageal cancer? Why can the cancer cause hoarseness?
Common symptom = trouble swallowing (dysphasia)
Can cause hoarseness by compression of the recurrent laryngeal nerve by the esophageal tumor
Which muscles contract to close the laryngeal inlet? What is the stimulus for the reflexive contraction? When is the reflex diminished?
Close the laryngeal inlet = ary-epiglottic muscles + lateral circo-arythenoids + arytenoids (lateral + oblique)
Stimuli = anything even near the laryngeal vestibules
Reflex diminished when you are unconscious
How can facial infections spread to the cavernous sinus or pterygoid venous plexus?
Facial vein makes connections w/ the superior ophthalmic vein that allows for infections to enter the cavernous sinus
Facial vein via the inferior ophthalmic vein or the deep facial vein can go to the pterygoid venous plexus
How does thrombophlebitis of the cavernous sinus typically occur?
Can happen if there’s thrombophlebitis of the facial vein…the infected thrombus can go to the cavernous sinus via the superior ophthalmic vein
Why can fracture of the pterion be life threathening?
It can cut the anterior branch of the middle meningeal artery that crosses underneath the pterion
This can give you a hematoma that puts pressure on the cerebral cortex
How do the sources & locations of extravasted blood differ w/ an epidural hematoma, dual border hematoma, & subarachnoid hematoma
Epidural - Rupture of middle meningeal artery that causes blood to pool outside of the cranial dura/periosteal layer
Dual border - Rupturing of the superior cerebral vein as it enters the superior sagittal sinus…causes pooling of blood b/w the dura and the arachnoid
Subarachnoid - Rupturing of an arterial saccular aneuryism (aka Berry aneuryism) into the subarchnoid space
How are closure defects associated w/ exencephaly & craniorachischsis differ? How can they be prevented?
Exencephaly - Closure of the cranial end doesn’t happen
Craniorachischsis - Same as exencephaly but extends to the spinal cord as well
400 miligrams of folic acid will prevent this
Where does obstruction occur during obstructive hydrocephalus? Why do the calvaria expand?
Obstruction = cerebral aqueduct or interventricular foramen
The calvaria expands b/c the sutures & fontanelles are still open and cope w/ the growing size of the cranium
Where do cranial fractures occur that result in otorrhea or rhinorrhea? Why do these conditions increase the risk of meningitis?
Otorrhea = CSF from ear so in the floor of the middle cranial fossa
Rhinorrhea = CSF from nose so in the floor of the anterior cranial fossa
Increases risk of meningitis b/c you have new routes for infecting agents to enter the meninges
How do the frequency & severity of bacterial & viral meningitis differ?
Bacterial is less common & more severe
Why do glial cells form most intracranial tumors?
This is b/c glial cells make up the majority of the cells and also b/c they have the ability to undergo mitosis post-natally
Neurons don’t divide after birth
How do astrocytes respond to CNS injury?
They undergo mitosis & produce gliotic scar tissue that can potentially impede neuronal regeneration
Why are normal anastomoses b/w cerebral arteries not capable of compensating for arterial obstruction by a cerebral embolism?
They are microvessels that are too small to make up for the lost area
What is the typical cause of ischemic stroke? What is the cardinal symptom?
Embolism in a major cerebral artery
Cardinal symptom = Sudden onset of neurological symptoms
What is a berry aneurysm & where does it occur commonly?
It’s a saccular aneurysm that forms in vessels of the cerebral arterial circle
Commonly found when the basilar artery branches into the posterior cerebral artery
How is an hemorrhagic stroke different from a ischemic stroke?
Hemorrhagic stroke is due to bleeding out from a ruptured vessel or saccular aneurysm
How do the affects of interrupted blood flow to the brain differ after 30 sec, 1-2 min, & 5 min
30 sec = Alteration of brain metabolism
1-2 min = Neural function lost
5 min = Cerebral infarcation
What are the symptoms of transient ischemic attack?
Staggering, dizziness, light-headedness, fainting & paresthesia
Why can visual deficits result from pituitary tumors? How is the gland surgically accessed?
The pituitary gland is found anterolaterally to the optic chiasm & optic nerve
Sphenoid sinus found inferior to the pituitary gland used to access the tumor
What are the causes & symptoms of diabetes insipidus?
Symptoms: polyuria & polydipsia
Causes: Damage of the supraoptic & paraventricular nuclei on the hypothalamus or destruction of the hypothalamophyseal tract —> affects production & release of ADH
