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For each of the following foramina, identify the nerve(s) that pass through that foramen:
- Superior orbital fissure; Oculomotor, trochlear, abducent, and V1
- Rotundum; V2
- Ovale; V3, lesser petrosal (occasionally)
- Internal acoustic meatus; Facial and vestibulocochlear
- Jugular; Glossopharyngeal, vagus, and spinal accessory
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About how much CSF is produced per day, and where is it reabsorbed into the venous system?
About 500 mL/day is produced; CSF is reabsorbed by the arachnoid granulations (most significant site) and small capillaries along the brainstem and spinal cord.
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Trace venous blood in the superior petrosal sinus to the right atrium.
Superior petrosal sinus to sigmoid sinus to internal jugular vein to brachiocephalic vein (right or left) to superior vena cava to right atrium.
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For each intracranial hematoma, suggest the most likely vascular source:
- Epidural; Arterial, usually the middle meningeal or its branches
- Subdural; Venous, often the cortical bridging veins
- Subarachnoid; Arterial, often from saccular (berry) aneurysms
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How is the facial cranial nerve classified functionally?
- GSA: sensory to the skin of the ear
- SVA: special sense of taste to the anterior two-thirds of the tongue
- GVE: motor to glands; salivary, nasal, and lacrimal
- SVE: motor to muscles of facial expression and those from the second pharyngeal arch
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Trace the pathway of tears from the lacrimal gland to the nasal cavity.
Lacrimal gland (CN VII secretomotor fibers) to lacrimal ducts to bulbar conjunctival and corneal surfaces, then to lacrimal lake, to lacrimal punctum (superior and inferior) to lacrimal canaliculi to lacrimal sac, down the nasolacrimal duct and into the inferior meatus of the inferior nasal concha.
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During clinical testing of the extraocular muscles, which two muscles elevate the eye and what nerves innervate them?
SR (CN III) and IO (CN III), in abduction and adduction, respectively.
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Define the following refractive disorders:
- Myopia: Nearsightedness; difficulty seeing distant objects clearly
- Hyperopia: Farsightedness; difficulty seeing close objects clearly
- Presbyopia: Progressive loss of ability to accommodate the lens and clearly focus on close objects
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What is glaucoma, and which type is most common?
Resistance to the outflow of aqueous humor, usually primary open angle, resulting from impedance at the canal of Schlemm or of the trabecular meshwork, or from venous backpressure.
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Account for each clinical sign of Horner's syndrome.
- Ptosis: loss of innervation of superior tarsal (smooth) muscle (distal part of levator palpebrae muscle of upper eyelid)
- Miosis: loss of innervation of dilator muscle of the pupil
- Anhydrosis: loss of innervation of sweat glands
- Flushed face: unopposed vasodilation of cutaneous vessels
- (Each sign represents loss of sympathetic innervation)
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What nerve innervates the parotid salivary gland?
Preganglionic parasympathetic fibers from CN IX (inferior salivatory nucleus) innervate the gland and travel via the lesser petrosal nerve to the otic ganglion, where they synapse. Postganglionic fibers then jump onto the auriculotemporal branch of V3�and pass to the parotid gland (secretomotor fibers).
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What deficits might be expected if the chorda tympani nerve is damaged?
Loss of salivary secretion in the submandibular and sublingual salivary glands, and loss of taste from the anterior two-thirds of the tongue.
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Which paranasal sinuses drain into the middle meatus beneath the middle nasal concha?
Frontal, maxillary, and anterior and middle ethmoid sinuses.
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Identify the five nerves innervating the tongue.
Motor: CN XII; sensory: CN V3�(anterior), CN IX (posterior), and CN X (epiglottis); taste: CN VII (anterior) and CN IX (posterior).
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What nerve(s) innervate the infrahyoid muscles (strap muscles) of the neck?
Ansa cervicalis (C1-C3) of the cervical plexus.
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Where can one find the phrenic nerve in the neck, and what does it innervate?
The phrenic nerve (C3-C5) appears on the anterior surface of the anterior scalene muscle and innervates the diaphragm.
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What are the arterial branches of the thyrocervical trunk?
Inferior thyroid, transverse cervical, and suprascapular.
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During thyroid surgery, what nerve must be identified and preserved?
Recurrent laryngeal nerve, which innervates the muscles of the larynx.
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What are the three subdivisions of the pharynx?
Nasopharynx, oropharynx, and laryngopharynx (called hypopharynx by many clinicians).
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What is the retropharyngeal space, and why is it important?
A potential space between the alar and prevertebral fascial layers. An infection in this space can spread superiorly to the base of the skull or inferiorly into the posterior mediastinum.
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What is Waldeyer's tonsillar ring?
A ring of lymphoid tissues around the oropharynx including the palatine, lingual, and nasopharyngeal tonsils.
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Where are the neurons located that give rise to all postganglionic sympathetic fibers innervating the head?
Superior cervical ganglion.
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Developmentally, the hindbrain gives rise to what CNS regions?
Metencephalon (pons and cerebellum) and myelencephalon (medulla oblongata).
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What cranial nerve is associated with the third pharyngeal arch, and what bones or cartilages are derived from this arch?
CN IX (innervates the stylopharyngeus muscle); the inferior half and greater horns of the hyoid bone are derived from the third arch.
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How would you clinically test each CN?
- NERVE, EXAMINATION, FINDINGS/DEFICITS
- I, Test smell in each nostrils, Trauma, infection leading to: Hyposmia (partial loss), Anosmia (total loss), Hyperosmia (exaggerated), Dyosmia (distorted sense)
- II, Test acuity, fields, optic disc, Altered acuity or blindness, hemianopsia, papilledema, optic atrophy
- II and III, Test pupillary reflex to light, Horner's syndrome, tonic pupil, Argyll Robertson pupil, gaze paresis
- III, IV, VI, Test ocular movements, Diplopia, strabismus, nystagmus, ophthalmoplegia, nerve palsies
- V, Test sensory over its three divisions, motor to jaw muscles, corneal reflex, Lesion to higher centers or nerve Corneal reflex tests integrity of V1 (and VII for blink)
- VII, Test muscles of facial expression, test taste on anterior two-thirds of tongue, Lesion centrally or to nerve as in Bell's palsy, parotid tumor, MS
- VIII, Perform Weber test (lateralization) and Rinne test (air-bone conduction), Perceptive or conductive tinnitus, vertigo
- IX, X, Test gag reflex, swallowing, soft palate elevation with "ahhh" sound, Usually central lesions, stroke, malignancy, motor neuron disease
- XI, Rotate head against resistance, weakness/atrophy; elevate shoulders, SCM/trapezius tumor, spasmodic torticollis
- XII, Inspect and protrude tongue; listen to patient's articulation, Unilateral nerve lesion: tongue protrudes to affected side, atrophy
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An imaginary horizontal line drawn posteriorly, connecting the iliac crests, will pass through which vertebral level?
Spinous process of L4 and the intervertebral disc of L4-L5.
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Why is the line connecting the iliac crests clinically important?
It is a useful landmark for a lumbar puncture or epidural block.
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What are the lay terms for the following accentuated curvatures?
- Lordosis: Swayback
- Kyphosis: Hunchback
- Scoliosis: Curved back
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Two laminae fuse to form what vertebral feature?
Spinous process.
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What are the craniovertebral joints?
Synovial joints between the atlas and occipital bone (atlantooccipital joint) and between the atlas and axis (atlantoaxial joint).
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Most herniated intervertebral discs occur at which vertebral levels?
L4-L5 or L5-S1.
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What embryonic structure gives rise to the nucleus pulposus of the intervertebral disc?
Notochord.
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A herniated disc at the L4-L5 level that impinges on a spinal nerve root will most likely involve components of which spinal nerve?
L5.
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Which vertebral joint allows for turning the head side-to-side, to indicate "no"?
Atlantoaxial joint.
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Which vertebral ligament connects adjacent laminae?
Ligamentum flavum.
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How can the back muscles be grouped functionally?
Into three groups: superficial (upper limb muscles), intermediate (muscles of respiration), and deep (postural muscles).
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Which back muscle is innervated by the dorsal primary rami of spinal nerves?
Deep intrinsic back muscles.
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What are the three major groups of erector spinae muscles?
Iliocostalis, longissimus, and spinalis muscles.
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What important artery passes through the transverse foramina of C1-C6 and appears in the suboccipital triangle?
Vertebral artery, a branch of the subclavian in the neck.
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How are the 31 pairs of spinal nerves distributed regionally?
8 cervical, 12 thoracic, 5 lumbar, 5 sacral, and 1 coccygeal pair.
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Each peripheral nerve arising from the spinal cord may contain hundreds of three types of axons. What are these types of axons?
Somatic efferent (motor) axons, afferent (sensory) axons, and postganglionic sympathetic axons.
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What is the term for the region of skin innervated by cutaneous fibers from a single spinal cord segment?
Dermatome.
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Where is CSF found?
In the brain ventricles, spinal central canal, and subarachnoid space of the brain and spinal cord.
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What arteries run the length of the spinal cord, and where are they situated?
A single anterior artery and two posterior arteries run the length of the spinal cord.
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What portion of the embryonic somite gives rise to the cartilaginous precursor of the axial skeleton?
Sclerotome.
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What is a common neural tube defect that leads to incomplete development of the vertebral arch?
Spina bifida.
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What ectodermal derivative gives rise to the central nervous system (brain and spinal cord)?
Neural tube.
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