Clinically based questions

Brain Morphology (part II)

By Dr. Noura El-Tahawy

See the answers at the end of these questions

21. Which of the following Brodmann areas represents the primary somatomotor

cortex?

_ (A) Areas 3,1,2

_ (B) Area 4

_ (C) Area 5

_ (D) Area 6

_ (E) Area 7

22. A 39-year-old woman complains of weakness in her right lower extremity.The

history suggests that this deficit has developed slowly over several years. MRI

shows a meningioma السحائية باالغشية الحميدة االورام من imposing on the نوع

cerebral cortex. Which of the following gyri is most likely involved in this patient?

_ (A) Anterior paracentral

_ (B) Inferior part of precentral

_ (C) Superior part of precentral

_ (D) Superior part of postcentral

_ (E) Posterior paracentral

23. A 71-year-old woman presents with motor and sensory deficits affecting her

face and upper extremity. CT shows a hemorrhage that is confined largely to the

cortex and adjacent subcortical areas. Which of the following vessels/segments are

most likely involved?

_ (A) A1

_ (B) M2

_ (C) M3

_ (D) M4

_ (E) P

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24. A 73-year-old woman presents with visual deficits in both eyes. No other cranial

nerve deficits or motor or sensory deficits are seen. CT shows a hemorrhage in the

cerebral cortex. Which of the following vessels/segments is most likely involved in

this hemorrhage?

_ (A) A1

_ (B) M3

_ (C) M4

_ (D) P2

_ (E) P4

25. The CT of a 77-year-old man shows a calcified tuft of choroid plexus, the

glomus choroideum. Which of the following represents the location of this part of

the choroid plexus?

_ (A) Anterior horn of the lateral ventricle

_ (B) Atrium of the lateral ventricle

_ (C) Body of the lateral ventricle

_ (D) Roof of the third ventricle

_ (E) Temporal horn of the lateral ventricle

26. Which of the following represents the most common cause of blood in the

subarachnoid space (subarachnoid hemorrhage)?

_ (A) Bleeding from an arteriovenous malformation

_ (B) Bleeding from a meningioma

_ (C) Bleeding from a tumor

_ (D) Rupture of an aneurysm

_ (E) Trauma to the brain

27. The abducens nerve exits the brainstem at the pons-medulla junction generally

in line with the preolivary sulcus and passes rostrally just lateral to, and in the same

cistern as, the basilar artery. Which of the following cisterns contains the abducens

nerve and basilar artery?

_ (A) Ambient

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_ (B) Inferior cerebellopontine

_ (C) Premedullary

_ (D) Prepontine

_ (E) Superior cerebellopontine

28. An 81-year-old woman is brought to the emergency department by her son with

a complaint of weakness on the same side of her body and face. CT shows a

hemorrhage in the territory of the lenticulostriate arteries. Which of the following

represents the origin of these vessels?

_ (A) A1

_ (B) M1

_ (C) M2

_ (D) P1

_ (E) P2

29. The MRI of a 27-year-old woman shows a meningioma impinging on the gyrus

rectus in axial and coronal MRI. This lesion is located on which of the following

lobes of the cerebral hemisphere?

_ (A) Frontal

_ (B) Insular

_ (C) Occipital

_ (D) Parietal

_ (E) Temporal

30. A 51-year-old man presents with visual field deficits in both eyes and a right-

sided weakness of the upper and lower extremities. MRI shows a lesion in the optic

tract that has spread into a structure located immediately adjacent to this tract.

Based on its anatomical relationship, which of the following structures is most

likely involved in a lesion spreading from the optic tract?

_ (A) Left basilar pons

_ (B) Left crus cerebri

_ (C) Left pyramid

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_ (D) Right crus cerebri

_ (E) Right optic nerve

31. A 19-year-old man presents with significant paralysis of movement in his left

eye and a dilated pupil. No other deficits are seen. Suspecting some type of lesion

on the root or along the intracranial course of the oculomotor (III) nerve, the

neurologist orders an MRI. Which of the following describes the appearance of the

subarachnoid and ventricular spaces in a T2- weighted image?

_ (A) Black (hypointense)

_ (B) Dark grey

_ (C) Light grey

_ (D) Medium grey

_ (E) White (hyperintense)

32. A 49-year-old woman presents with ill-defined neurologic deficits that have

persisted over several months. As part of the evaluation, the neurologist orders an

MRI. Which of the following describes the appearance of CSF in the ventricular

spaces, and consequently the outline and shape of the ventricles, in a T1-weighted

image?

_ (A) Black (hypointense)

_ (B) Dark grey

_ (C) Light grey

_ (D) Medium grey

_ (E) White (hyperintense)

33. A 71-year-old morbidly obese man is brought to the emergency department by

his son. The son reports that the man complained of a sudden excruciating

headache اليطاق غيبوبة and then became stuporous صداع فى Suspecting a .وقع

ruptured aneurysm the physician orders a CT. Which of the following describes the

appearance of acute blood in the subarachnoid space in CT?

_ (A) Black (hypodense)

_ (B) Black to grey

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_ (C) Light grey

_ (D) Medium grey

_ (E) White (hyperdense)

34. Which of the following cranial nerves exits the brainstem via the preolivary

sulcus?

_ (A) Abducens (VI)

_ (B) Facial (VII)

_ (C) Hypoglossal (XII)

_ (D) Vagus (X)

_ (E) Trigeminal (V)

35. Which of the following cranial nerves exits the posterior (dorsal) aspect of the

brainstem?

_ (A) Abducens (VI)

_ (B) Hypoglossal (XII)

_ (C) Trigeminal (V)

_ (D) Trochlear (IV)

_ (E) Vestibulocochlear (VIII)

36. Which of the following cranial nerves passes between the posterior cerebral

artery and the superior cerebellar artery as it exits the brainstem?

_ (A) Abducens

_ (B) Oculomotor

_ (C) Optic

_ (D) Trigeminal

_ (E) Vestibulocochlear

37. The MRI of an 11-year-old boy shows a tumor in the pontine portion of the

fourth ventricle. The rostral edge of which of the following structures represents the

border between the medullary and pontine parts of the fourth ventricle?

_ (A) Facial colliculus

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_ (B) Hypoglossal trigone

_ (C) Medial eminence

_ (D) Stria medullares

_ (E) Vagal trigone

38. A 61-year-old man presents with a tremor and unsteady gait; these problems are

on the same side of his body. Sagittal MRI shows a lesion in the anterior lobe of the

cerebellum. Which of the following represents the fissure separating the anterior

and posterior lobes of the cerebellum?

_ (A) Horizontal fissure

_ (B) Posterior superior fissure

_ (C) Posterolateral fissure

_ (D) Primary fissure

_ (E) Secondary fissure

39. The MRI of a 49-year-old woman with a brain tumor shows tonsillar herniation.

Based on its anatomical position, which of the following portions of the brainstem

would be most adversely affected by tonsillar herniation?

_ (A) Caudal midbrain

_ (B) Caudal pons

_ (C) Medulla

_ (D) Rostral midbrain

_ (E) Rostral pons

40 .A sagittal MRI of a 52-year-old man clearly shows a small tumor in the area of

the long and short gyri. These gyri are characteristically found in which of the

following lobes?

_ (A) Frontal

_ (B) Insular

_ (C) Limbic

_ (D) Occipital

_ (E) Parietal

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41. A lesion involving the root of which of the following nerves would most likely

have an effect on the gag reflex?

_ (A) Spinal accessory

_ (B) Facial

_ (C) Glossopharyngeal

_ (D) Hypoglossal

_ (E) Trigeminal

Answers of clinically based questions

Brain Morphology (Part II)

21. Answer B: The primary somatomotor cortex consists of the precentral gyrus

and the anterior paracentral gyrus or lobule; area 4 is found in these structures.

Areas 3, 1, and 2 are the somatosensory cortex; areas 5 and 7 make up the superior

parietal lobule and the precuneus; and area 6 is located anterior to area 4. Portions

of area 6 in the posterior region of the middle frontal gyrus are the frontal eye field.

22. Answer A: In this patient, the meningioma is located in the falx cerebri and is

impinging on the anterior paracentral gyrus correlating with her motor deficit. The

lower extremity is represented in the anterior paracentral gyrus (somatomotor) and

in the posterior paracentral gyrus (somatosensory) (both represent the paracentral

lobule and located on the medial surface of the cerebrum). The precentral gyrus (on

the lateral surface of the cerebrum) contains at its lower part the motor

representation for the face while its upper part represents the trunk and hip. The

postcentral gyrus is part of the somatosensory cortex.

23. Answer D: The M4 segments of the middle cerebral artery serve the lateral

aspect of the cerebral hemisphere. The named M4 vessels that serve the pre- and

postcentral gyri (hemorrhage into approximately the lower two-thirds of these gyri

explain the motor and sensory deficits) are the precentral branches (prerolandic),

central branches (Rolandic branches), and anterior parietal branches. The M2

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segment serves the insular cortex, and the M3 segment serves the inner surface of

the frontal, parietal, and temporal opercula. The A1 segment (first part of anterior

cerebral artery) supplies hypothalamic structures, the subcallosal and septal areas,

and adjacent structures. P4 (terminal or 4th part of posterior cerebral artery) serves

the medial aspect of the occipital lobe (visual cortex).

24. Answer E: The P4 segments (Terminal parts of the posterior cerebral artery)

consist of the parieto-occipital and calcarine branches; the latter being located in the

calcarine sulcus and a primary blood supply to the primary visual cortex. M3 and

M4 segments of the middle cerebral are located, respectively, on the inner aspect of

the frontal, parietal, and temporal opercula and on the lateral aspect of the cerebral

hemisphere. The P2 segment of the posterior cerebral artery is located just distal to

the posterior communicating–posterior cerebral intersection and gives rise to medial

and lateral posterior choroidal and to thalamogeniculate arteries. The A1 segment is

located between the internal carotid and anterior communicating artery and gives

rise to branches that serve anterior hypothalamic structures, septal areas, and the

optic chiasm.

25. Answer B: The glomus choroideum is found in the atrium of the lateral

ventricle. This part of the choroid plexus is continuous with that in the body of the

lateral ventricle and continuous anteroinferiorly with that in the temporal horn. The

roof of the third ventricle has a small portion of choroid plexus that is continuous

with that in the body of the ventricle via the interventricular foramen. The anterior

horn contains no choroid plexus.

26. Answer E: Trauma is the most common cause of subarachnoid hemorrhage

(SAH). The most common cause of spontaneous (also called nontraumatic) SAH is

bleeding from a ruptured aneurysm (about 75% of all spontaneous cases). Bleeding

from an arteriovenous malformation (AVM) is an infrequent cause of SAH (about

5% of cases), and bleeding from brain tumors into the subarachnoid space is rare.

Meningiomas are usually slow-growing tumors that may have a rich vascular supply

but rarely hemorrhage spontaneously.

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27. Answer D: The prepontine cistern is located external to the basilar pons and

contains the abducens nerve, basilar artery, origin of the anterior inferior cerebellar

artery, and small perforating arteries and veins. The ambient cistern is located on

the lateral aspect of the midbrain and contains the trochlear nerve and several major

arteries. The premedullary cistern is located at the anterior surface of the medulla

and contains the anterior spinal artery. The inferior cerebellopontine cistern contains

the glossopharyngeal, vagus, and accessory nerves. The superior cerebellopontine

cistern contains the trigeminal, facial, and vestibulocochlear nerves plus a short

segment of the trochlear nerve.

28. Answer B: Lenticulostriate arteries, also called the lateral striate arteries,

originate from the M1 (part1) segment of the middle cerebral artery and serve

much of the lenticular nucleus and adjacent parts of the internal capsule. A1

branches of the anterior cerebral artery serve the anterior hypothalamus and optic

chiasm, and M2 branches of middle cerebral serve the insular cortex. The P1 and P2

segments of the posterior cerebral artery give rise to many small perforating

branches and to the thalamoperforating and quadrigeminal arteries (P1), medial and

lateral posterior choroidal arteries, and the thalamogeniculate artery (P2).

29. Answer A: The gyrus rectus is located on the inferior aspect of the frontal lobe

medial to the orbital gyri. It is separated from the orbital gyri by the olfactory sulcus

in which the olfactory bulb and tract is located. None of the other lobes has a direct

relationship to the gyrus rectus.

30. Answer B: The optic tract lies immediately on the surface of the crus cerebri, a

relationship frequently seen in MRI. The fact that this patient has a right-sided

weakness of the extremities specifies that the lesion is in the left crus cerebri. The

bilateral visual deficits correlate with damage to the left optic tract. Lesions of the

left basilar pons and pyramid would result in a right-sided weakness but no visual

deficits. A lesion in the right optic nerve would result in blindness in that eye but no

weakness of the extremities.

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31. Answer E: Cerebrospinal fluid in the ventricles, and throughout the

subarachnoid space, appears very white in T2-weighted MRI images. Structures

located in, or traversing the subarachnoid space (such as vessels or cranial nerve

roots, including the oculomotor nerve) appear grey to black against a white

background.

32. Answer A: Cerebrospinal fluid, and other fluids, appear black in T1-weighted

MRI images. Consequently, the ventricles, and more obvious parts of the

subarachnoid space, appear black. Changes in ventricular shape (i.e., enlargement,

midline shift), or obliterated sulci, or even subarachnoid space, most likely

represent a potentially serious clinical issue.

33. Answer E: Patients who experience rupture of an intracranial aneurysm

frequently complain of an intense, sudden headache (“the most horrible headache I

have ever had”). Acute blood in the subarachnoid space will appear white to very

white on CT. This will contrast with the medium grey of the brain and the black of

cerebrospinal fluid (CSF) in the ventricles. The degree of white may vary

somewhat, based on the relative concentration of blood, from very white

(concentrated blood) to white (mostly blood, some CSF), to very light grey (mixture

of blood and CSF).

34. Answer C: The hypoglossal nerve exits the medulla via the preolivary sulcus of

the medulla immediately (and laterally) adjacent to the pyramid. The abducens

nerve exits in line with the preolivary sulcus, but, at the caudal edge of the pons,

and the trigeminal nerve exits the lateral aspect of the pons. The vagus nerve exits

the lateral aspect of the medulla via the postolivary sulcus, and the facial nerve in

line with this sulcus, but at the pons-medulla junction.

35. Answer D: The trochlear nerve exits the posterior (dorsal) aspect of the

brainstem just caudal to the inferior colliculus and passes around the lateral aspect

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of the midbrain in the ambient cistern, en route to its exit from the skull via the

superior orbital fissure. The abducens nerve exits at the caudal edge of the pons in

line with the preolivary fissure, and the hypoglossal exits from the medulla via this

fissure. The trigeminal nerve exits the lateral aspect of the pons, and the

vestibulocochlear nerve exits at the most lateral aspect of the pons-medulla

junction.

36. Answer B: As it exits the anterior (ventral) surface of the midbrain, the

oculomotor nerve passes between the superior cerebellar artery (which is caudal to

the nerve root) and the P1 segment of the posterior cerebral artery (which is rostral

to the nerve root). The trigeminal root is adjacent to more distal portions of the

superior cerebellar artery; the labyrinthine artery accompanies the vestibulocochlear

nerve as it enters the internal acoustic meatus; and the ophthalmic artery

accompanies the optic nerve along part of its extent. The abducens nerve passes

rostrally adjacent to the basilar artery in the prepontine cistern.

37. Answer D: The rostral edge of the striae medullares (of the fourth ventricle) is

regarded as the border between the pontine and medullary portions of the fourth

ventricle. These fibers pass from the median fissure in the floor of the ventricle

laterally into the lateral recess where they arch up into the cerebellum. The facial

colliculus and median eminence are located in the floor of the pontine portion of the

ventricle, and the vagal and hypoglossal trigones are found in the medial floor of the

medullary portion of the fourth ventricle.

38. Answer D: The primary fissure is the deepest fissure in the cerebellum and it

separates the anterior lobe from the posterior lobe and extends from the vermis to

the lateral cerebellar margin. The posterolateral fissure is located between the

flocculonodular lobe and the posterior lobe. The horizontal, secondary, and

posterior superior fissures are all located within the posterior lobe.

39. Answer C: The tonsil of the cerebellum is found on the anterior and inferior

aspect of the cerebellar hemisphere, adjacent to the midline and immediately

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posterior (dorsal) to the medulla. The cisterna magna is located in this area. Sudden

tonsillar herniation may compress the medulla and damage respiratory and cardiac

centers resulting in sudden death. The tonsil herniates downward through the

foramen magnum. Consequently, no other part of the brainstem is directly affected.

40. Answer B: The long and short gyri (gyri longi et breves) are components of the

insular lobe. This lobe is located deep to the lateral sulcus, has a central sulcus that

separates the short gyri (rostral to this sulcus) from the long gyri (caudal to this

sulcus). The cortex of the insular lobe is separated from the adjacent frontal,

parietal, and temporal opercula by the circular sulcus of the insula. None of the

other lobes has gyri that are specifically named long and short gyri.

41. Answer C: The glossopharyngeal nerve contains the afferent limb of the gag

reflex and, through its innervation of the stylopharyngeus muscle, is an important

part of the efferent limb of this reflex. The nucleus ambiguus, the location of the

motor neurons serving the stylopharyngeus, also contributes to the innervation of

muscle served by the vagus nerve and, therefore, to the efferent limb of the gag

reflex. The trigeminal and facial nerves participate in the afferent and efferent limbs

(respectively) of the corneal reflex. The spinal accessory nerve innervates the

ipsilateral trapezius and sternocleidomastoid muscles, and the hypoglossal nerve

innervates the ipsilateral genioglossus muscle.

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