part 2- Neuroanatomy - Q And A clinical cases

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part 2- Neuroanatomy - Q And A clinical cases

  1. 1. 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 ‫ نوع من الورام الحميدة بالغشية السحائية‬imposing on the 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 1
  2. 2. 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 2
  3. 3. _ (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 3
  4. 4. _ (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 ‫ صداع ليطاق‬and then became stuporous ‫ .وقع فى غيبوبة‬Suspecting a 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 4
  5. 5. _ (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 5
  6. 6. _ (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 A sagittal MRI of a 52-year-old man clearly shows a small tumor in the area of .40 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 6
  7. 7. 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 7
  8. 8. 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. 8
  9. 9. 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. 9
  10. 10. 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 10
  11. 11. 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 11
  12. 12. 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. 12

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