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BRT | ANATOMY

Neuroanatomy

May 4, 2015

NEUROANATOMY (for questions 1-4) A 25 year old male presents to the ER with a severe contusion to the right side of the forehead. On examination, he has diminished sensation to the forehead and cannot raise the upper eyelid. Further examination shows that he cannot move the eye upward or in a lateral direction. Radiographic studies show some displacement of the bony structures of the orbit. 1. Which is the site into which the bone has been displaced, resulting in all

of the described symptoms? a. Mental foramen b. Supraorbital foramen c. Infraorbital foramen d. Superior orbital fissure e. Inferior orbital fissure

ANSWER: D

V1, CN III, IV, VI all pass through superior orbital fissure which explains decreased sensation (V1), loss of ability to raise eyelid (levator palpebrae superioris: III), and move eye upward (inferior oblique and superior rectus: III) and laterally (lateral rectus: VI).

2. Which nerve is involved in the patient’s inability to look upward or raise the upper eyelid?

a. Trochlear b. Oculomotor c. Abducens d. Frontal e. Ophthalmic division of trigeminal nerve (V1)

ANSWER: B

Superior division of oculomotor nerve supplies the levator palpebrae superioris,superior rectus and inferior oblique muscles with motor innervation

Muscle Primary Action Secondary Action CN

Medial Rectus Adduction III Lateral Rectus Abduction VI Superior Rectus Elevation Intorsion III Inferior Rectus Depression Extorsion III Superior Oblique Intorsion Depression IV Inferior Oblique Extorsion Elevation III

3. Which nerve is involved in the patient’s inability to move the eye in a

lateral direction? a. Trochlear b. Oculomotor c. Abducens d. Supratrochlear e. Infraorbital

ANSWER: C

Abducens nerve –supplies the lateral rectus muscle, allows for lateral gaze.

Trochlear nerve –supplies the superior oblique muscle, not involved in the patient’s deficit since he is able to perform downward and inward gaze.

LASOT: Lateral rectus Abducens; Superior Oblique Trochlear 4. Sensory deficit is a result of injury to which nerve?

a. Zygomaticofacial b. Zygomaticootemporal c. First cervical spine nerve (C1) d. Maxillary division of trigeminal (V2) e. Ophthalmic division of trigeminal (V1)

ANSWER: E

Ophthalmic nerve supplies sensory innervation to the forehead and the scalp as far as the vertex.

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Anatomy | Neuroanatomy

5. Where would a lesion resulting in a fluent (sensory) Wernicke aphasia most likely be found?

a. Temporal lobe b. Parietal lobe c. Frontal lobe d. Occipital lobe e. Limbic lobe

ANSWER: A

Specifically, posterior parasylvian temporal operculum

Parietal lobe – sensory association areas; a lesion in this area will produce hemineglect, apraxia, Gerstmann syndrome (dysgraphia, dyscalculia, left/right disorientation, finger agnosia)

Frontal lobe – personality, mood, insight

Occipital lobe – primary visual area

Limbic – basic human emotion; learning processes

Type of Aphasia

Fluency Understand

Repetition

Naming

Location of Leson

Broca’s Poor; effortful

Good Poor poor Left posterior inferior frontal operculum

Wernicke’s Good; word salad

Poor Poor Poor Posterior parasylvian temporal operculum

Conduction Good; poor articulation

Good Poor Poor Posterior parasylvian

Transcortical Motor

Poor Good Good May be normal

Frontally and superiorly extending inward to striatum

Transcortical Sensory

Good Poor Good Usually normal

Parietal, temporal involving thalamocortical unit

Global None or scanty; expletives only

Very poor Very poor

Very poor

Entire parasylvian

6. A patient presents with gait unsteadiness. When standing with his feet together, he is slightly unsteady. When he closes his eyes, he becomes markedly unsteady and must be held in order to avoid falling. Where is the disease located?

a. Dorsal column b. Lateral spinothalamic tract c. Anterior horn cells d. Lateral corticospinal tract e. Anterior white commissure

ANSWER: A

Dorsal column carries sensory perception (Rombergs sign)

Lateral spinothalamic tract carries pain and temperature

AHC final common pathway for muscle stimulation

Lateral CST innervate neurons for motor function (pyramidal tract)

Two of the five sensory modalities, pain and temperature, cross sides at the anterior white commissure, reaching the contralateral side about two vertebral levels rostral to their origin.

Legend. Gray matter: 1. Anterior horn; 2. Posterior horn; 3. Gray commissure. White matter: 4. Anterior funiculus; 5. Lateral funiculus; 6. Posterior funiculus; 7. Anterior

commissure; 8. Anterior median fissure; 9. Posterior median sulcus; 10. Central canal; 11. Anterior root; 12. Posterior root; 13. Dorsal root ganglion

7. A 60 year old man presents with sudden onset of speech arrest and

right-sided weakness. Examination shows 0/5 strength in the right arm, 3/5 strength in the right leg. Decreased right-sided sensation is also present. This combination most likely represents

a. Left anterior cerebral artery infraction b. Left middle cerebral artery infarction c. Right middle cerebral artery infarction d. Left lacunar infarction of anterior choroidal artery e. Subarachnoid hemorrhage of right posterior cerebral artery

ANSWER: B

Speech area located at Broca’s or dominant inferior frontal gyrus and contralateral primary sensorimotor area are both supplied by left MCA.

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Anatomy | Neuroanatomy

8. Which set of cranial nerves is closely related anatomically to the corticospinal tract as it passes longitudinally through the brainstem?

a. CN III, IV, V b. CN III, V, VII c. CN III, VI, VIII d. CN III, VI, XII e. CN III, IX, X

ANSWER: D

Test-taking strat: o The brainstem is comprised of the midbrain, pons and

medulla oblongata where cranial nerves III-IV, V-VIII and IX-XII, respectively, are located.

o The pyramidal tract runs through the entire brainstem until it decussates; thus options A, B, C (no cranial nerve located at the medulla oblongata) and E (no cranial nerve located at the pons)

9. The history and physical exam of a patient indicate a meningioma

within the tentorium cerebelli. You visualize this tumor as residing: a. Between the right and left cerebral hemispheres b. Within the operculum of the frontal lobe c. In the cisterna magna d. At the cerebellopontine angle e. Between the occipital lobe and the cerebellum

ANSWER: E

Between the right and left hemispheres – falx cerebri

The cisterna magna (or cerebellomedullary cistern) is one of three principal openings in the subarachnoid space between the arachnoidand pia mater layers of the meninges surrounding the brain.

The landmark tentorium cerebelli helps localize brain tumors in terms of type, frequency, etc. Pediatric brain tumors are most commonly found infratentorially whereas most adult tumors are supratentorial in location.

10. An aneurysm near the bifurcation of ICA into the anterior and middle

cerebral artery which deficit would most likely be associated with the lesion?

a. Olfactory b. Optic c. Oculomotor nerve d. Trigeminal

ANSWER: B

The majority of intracranial aneurysms arise from the internal carotid artery (ICA) circulation.

The proximity of cranial nerves II to VI to the pathway of the internal carotid artery make them susceptible to damage from an ICA aneurysm, which may cause a variety of neurologic effects.

Although vision loss is a relatively uncommon sequela of an ICA aneurysm, compression of the optic nerve by an aneurysm can cause visual field loss, decreased visual acuity, or both.

11. A 64 year old man diagnosed with permanent speech disorder (Broca’s

aphasia) from CVA which most likely involves: a. ACA b. MCA c. Lenticulostriate arteries d. PCA e. PICA

ANSWER: B

MCA supplies left frontal lobe operculum which contains Broca’s speech center

12. Where is the barrier between the blood and brain parenchyma?

a. Leaky ependymal (epithelial) b. Tight ependymal (epithelial) c. Capillary endothelium d. Neuronal membrane e. Fenestrated endothelium

ANSWER: C

Capillary endothelium provides the most significant barrier to substances having free access to the extracellular space of the cells within the brain

A, B – ependymal cells provide the lining of ventricular spaces 13. Which region begins closure of the neural tube?

a. Cranial end b. Caudal end c. Cervical region d. Lumbar region e. Sacral region

ANSWER: C

The closure of the neural tube occurs first in the cervical region, and progresses cranially and caudally simultaneously.

Failure of the neural tube to grow results in a variety of congenital anomalies, including spina bifida

14. An attending physician hands the intern a tuning fork and asks him to

test the perception of the vibratory modality in the individual that the physician is checking. Which system is tested using this instrument?

a. Spinothalamic (anterolateral) system b. Posterior spinocerebellar pathway c. Dorsal column-medial lemniscus system d. Tectospinal pathway e. Rubrospinal pathway

ANSWER: C

The dorsal column-medial lemniscus system carries the sensory modalities of two-point discrimination, vibration, and conscious proprioception

The spinothalamic (anterolateral) system evaluates temperature and sharp pain

The posterior spinocerebellar pathway is a sensory modality for unconscious proprioception

The tectospinal pathway observes change in the position of the neck, shoulders, upper trunk, visual and auditory stimuli

The rubrospinal pathway observes muscle tone, and coordination of proximal appendicular muscle groups

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Anatomy | Neuroanatomy

15. A 35-year old male patient, who has previously been aggressive and assaultive, injures his head in a boating accident. After the accident, the nurses report that although he is very easy to deal with, he constantly masturbates and often makes sexually suggestive gestures toward them. What is the most likely site of his brain injury?

a. Basal ganglia b. Hippocampus c. Amygdala d. Parietal lobes e. Frontal lobes

ANSWER: C

Damage to amygdala results in Kluver-Bucy syndrome which is characterized by docility and hypersexuality.

A Damage to basal ganglia results in movement disorder such as Parkinson’s

B damage to hippocampus is associated with memory deficits

D damage to parietal lobe is associated with intellectual processing of sensory information

E damage to frontal lobe results to problem with mood, concentration, and orientation

16. The pituitary gland is formed by the fusion of an evagination of the

third ventricle with an evagination of: a. ectoderm that forms the roof of the stomodeum b. endoderm that forms the roof of the pharynx c. endoderm that forms the first branchial pouch d. ectoderm that forms the first branchial cleft e. mesoderm that forms the first branchial arch

ANSWER: A

The pituitary gland is derived from two sources: 1) from evagination of the third ventricle forming the infundibulum of hypothalamus and 2) posterior lobe of pituitary gland.

The anterior lobe and pars intermedia are formed by Rathke’s pouch, which is an evagination of the ectoderm that forms the roof of the stomodeum or primitive oral cavity.

17. The occulomotor nerve passes between which pair of arteries?

a. Superior cerebellar artery and posterior cerebral artery b. Posterior inferior cerebellar artery and anterior inferior

cerebellar artery c. Posterior cerebral artery and middle cerebral artery d. Labyrinthine artery and anterior inferior cerebellar artery e. Posterior cerebral artery and posterior communicating artery

ANSWER: A

The oculomotor nerve emerges from the midbrain passing between the two cerebral peduncles.

The nerve passes between posterior cerebral artery and superior cerebellar artery before entering the dura of the lateral wall of the cavernous sinus.

Aneurysm of any of these two arteries will compress the oculomotor nerve

18. Which sequence best describes the path that a drop of cerebrospinal

fluid follows from the lateral ventricle to the superior sagittal sinus? a. Foramen of Magendie cerebral aqueduct 4th ventricle

arachnoid villi b. Formaen of Monro Foramen of Luschka 4th ventricle

cisterna magna c. Septum pellucidum 3rd ventricle 4th ventricle

foramen of Luschka

d. Arachnoid villi cisterna magna foramen of Magendie foramen of Monro

e. Foramen of Monro cerebral aqueduct foramen of Luschka arachnoid villi

ANSWER: E

19. As a result of a unilateral lower motor lesion of the hypoglossal nerve

would result in:

ANSWER: Deviation of the tongue ipsilaterally

The genioglossus muscle is paralyzed on the side of the lesion in the hypoglossal nerve.

When the tongue is protruded, the vector of fully innervated muscle is unopposed by the muscles of the opposite side, thereby producing an obvious deviation of the tongue from the midline.

Protrusion is still possible due to normal innervated side.

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Anatomy | Neuroanatomy

20. On angiography, which vessel follows the contour of the corpus callosum

a. Middle cerebral artery b. Vertebral artery c. Posterior cerebral artery d. Superior cerebellar artery e. Anterior cerebral artery

ANSWER: E RATIONALE:

A1 segment of anterior cerebral artery follows the contour of the corpus callosum

A MCA would run laterally in the lateral fissure before purging horizontally on the lateral brain surface

B Vertebral vessels would run along the ventral surface of the medulla

C PCA passes along the region along the cerebral peduncles of the midbrain and courses along the ventral surface of occipital lobes

D Superior cerebellar artery is similar to the PCA except under the cerebellar artery the dorsal surface of the cerebellum

21. The lentiform nuclei consist of the a. subthalamic nucleus and substantia nigra b. caudate nucleus and putamen c. putamen and globus pallidus d. caudate nucleus, putamen and globus pallidus e. ventral anterior and ventral lateral thalami

ANSWER: C

Lentiform nuclei consist of the putamen and globus pallidus. On cross section these nuclei have a lense like appearance.

A subthalamic nucleus and substantia nigra are the cephalic components of basal ganglia

B caudate nucleus and putamen are referred to as striatum

D caudate nucleus, and globus pallidus are referred to nuclei of basal ganglia

E Ventral anterior and ventral lateral thalami are thalamic specific nuclei related to motor system

22. The attending and resident physicians suspect a vascular occlusion or

rupture. Which one of the following vessels should be the primary suspect?

a. Middle cerebral artery b. Internal carotid artery at the cavernous sinus c. Superior cerebellar artery d. Posterior inferior cerebellar artery e. Anterior communicating artery

ANSWER: D

The findings in this case suggest a lesion involving structures in the lateral aspect of the brainstem medulla which is supplied by the PICA.

A,B, E – involved in vasculature in cerebrum

C. Superior cerebellar artery supplies the midbrain

Case: A 29 year old man goes to the ER because of a severe headache. The patient says that the headache, which seems localized to the area behind the ears, has been intermittent but persistent since he was involved in a beach volleyball game while on vacation. Shortly after he returned from his vacation, he made an appointment with his family physician because he was worried about the headache and the fact that he had developed noticeable clumsiness. An avid fitness enthusiast, he noted his performance was awkward and uncoordinated. When questioned, he mentioned unusually frequent bouts of nausea and vertigo. Physical examination reveals an alert, oriented, thin man with mild hoarseness and some difficulty swallowing oral secretions. The left side of his face is affected by Horner’s syndrome, and he has pronounced bilateral rotatory nystagmus in the primary position with all directions of gaze. He has decreased sensitivity to light touch on the left side of his face, flattening of the left nasolabial fold, and paresis of the left soft palate. Finger to nose testing shows left sided dysmetria. Wen asked to walk across the room, his gait is ataxic and he deviates to the left. There is diminished pain and thermal sensation on the right side. Reflexes are symmetric. There is no Babinski reflex, and the remainder of the motor and sensory examination is normal.

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Anatomy | Neuroanatomy

23. What is the most likely cause of the patient’s Horner’s syndrome?

a. Descending autonomic innervation from the hypothalamus b. Parasympathetic dystonia c. Compression of the sympathetic chain and superior cervical

ganglion in the neck as a result of torticollis d. A reactive conjunctivitis caused by the sand in the patient’s

eyes e. A hypothalamic cyst

ANSWER: A

Horner’s syndrome o Triad: miosis, ptosis, and loss of hemifacial sweating.

Case taken as a whole indicates damage to the descending autonomic system in the medulla

B, C, D, E – no indications based on the history since this will only produce very specific localized problems

24. Which brain stem pathway affected by the lesion is responsible for the

findings of diminished pain and thermal sensation on the right side? a. Dorsal column-medial lemniscus b. Anterolateral system (spinothalamic tract) c. Dorsal spinocerebellar tract d. Pontocerebellar tract e. Periaqueductal gray pathway

ANSWER: B

Located in the upper outer quadrant of the medulla.

Responsible for pain and temperature sensation from the opposite side of the body and sites of the medulla supplied by PICA.

25. The lack of a Babinski reflex indicates that which one of the following

pathways is intact? a. Anterolateral system (spinothalamic tract) b. Pyramidal (corticospinal) tract c. Dorsal column-medial lemniscus system d. Auditory system e. Olivocerebellar tract

ANSWER: B

Babinski sign indicates upper motor neuron damage. Since the patient does not exhibit Babinski, then this means that the descending corticospinal tract is intact

26. Involvement of which one of the following cranial nerves is responsible

for the findings of hoarseness and difficulty swallowing? a. Glossopharyngeal nerve b. Hypoglossal nerve c. Vagus nerve d. Spinal accessory nerve e. Trigeminal nerve

ANSWER: C

Hoarseness and difficulty of swallowing indicates weakness of the larynx and the pharynx respectively.

Motor innervation structures are primarily supplied by the vagus nerve.

Vagus cells responsible for efferent motor originates in nucleus ambiguuus.

Nucleus ambiguuus resides in part of the medulla supplied by PICA

A glossopharyngeal nerve motor innervation is not enough to influence primary movement in swallowing

B Innervates the tongue and not supplied by PICA

D no involvement sternomastoid and trapezius muscles

E Trigeminal nerve may be involved but involvement would manifest as loss of pain and temperature sensation on the face

27. What is the most likely diagnosis?

a. Wernicke’s syndrome b. Kluver-Bucy syndrome c. Weber’s syndrome d. Locked-in syndrome e. Wallenberg’s syndrome

ANSWER: E

Constellation of neural findings and involvement of the lateral aspect of medulla indicates Wallenberg syndrome or lateral medullary syndrome.

Affectation of the PICA in this case can be pointed out as the cause of this syndrome

A involves parietotemporal lobe and is primarily a speech related disorder

B involves amygdala and medial temporal lobe

C involves midbrain and oculomotor nerve palsy

D Involve pons