CNS Flashcards
Which of the following statements is correct regarding the cerebral circulation?
A The basilar artery is branch of the internal carotid
B The anterior cerebral artery is most likely to embolise
C The largest branch is the anterior cerebral artery
D The posterior communication artery joins the internal carotid artery and posterior cerebral artery
D
Explanation
The middle cerebral artery is the largest vessel. The middle and anterior cerebral arteries branch off the internal carotid artery (ICA), the basilar artery is a branch of the vertebral artery. Near their termination, the internal coartids are joined to the posterior cerebral arteries by the posterior cimmunicating arteries.
Extra: Don’t forget that the opthalmic artery is also a branch of the ICA
In relation to the circle of Willis, which of the following statements is correct?
A The middle cerebral artery (MCA) supplies the lateral surface of the brain and the temporal lobe
B The anterior cerebral artery (ACA), the posterior cerebral artery (PCA) and middle cerebral artery (MCA) are all branches of the internal carotid artery (ICA)
C Congenital aneurysms are more commonly found on the posterior cerebral artery (PCA)
D Most emboli lodge in the basilar part of the circle of Willis
A
Explanation
Congenital aneurysms are more commonly found on the anterior cerebraland anterior communicating artery. The posterior cerebral artery (PCA) is a branch of the basilar artery. Most emboli lodge in the carotid part of the circle of Willis, especially in the territory of the middle cerebral artery (MCA).
The dorsal column pathways synapse in which of the following?
A Pons
B Gracile and cuneate nuclei
C Thalamus
D Cerebellum
B
Explanation
The dorsal column (posterior white column) is wholly occupied by ascending fibers of the gracile and cuneate tracts. The two tracts end in the lower part of the medulla by synapsing with the cells of the gracile and cuneate nuclei. They are concerned with light (discriminative) touch, vibration sense, proprioception and the sense of fullness of the bladder and rectum
Regarding the medulla oblongata, which of the following statements is correct?
A Cranial nerves 8-12 arise from it
B Is largely within the middle cranial fossa
C It is the part of the brainstem between the pons and spinal cord
D Is supplied by anterior inferior cerebellar artery
C
Explanation
It is in the posterior cranial fossa. It is supplied by the vertebral and basilar arteries and the posterior inferior cerebellar artery. Cranial nerves 9, 10, and 12 arise from it.
Note: Cranial nerve 11 does not arise from the brainstem, rather from C1-5.
Extra: although the current textbook writes that CNXI nuclei arise form the nucleus of the spinal accessory nerve, a column of anterior horn motor neurons in the superior five or six cervical segments of the spinal cord, a web search also describes that the nerve has a cranial part and a spinal part. The cranial part lies in the medulla. (The cranial root arises from cells situated in the caudal part of the nucleus ambiguus of the medulla. Its fibers emerge from the lateral medulla below the roots of the vagus. The spinal part arises from a column of cells (the accessory nucleus) that extends from the first to the sixth cervical cord segments in the dorsolateral part of the ventral horn of the spinal cord)
neupsykey.com
Which of the following structures are not involved in the control of posture and movement?
A Spino-cerebellar tracts
B Lateral reticulo-spinal tract
C Tractus solitarius
D Vestibulo-spinal tract
C
Explanation
The spinocerebellar tracts convey unconscious proprioceptive information from cord to cerebellum. The reticulo- and vestibulo-spinal tracts synapse with interneurons which in turn project to motor neurons. The vestibulo-spinal tract is of great importance for posture and balance. The reticulo-spinal tract Integrates information from the motor systems to coordinate automatic movements of locomotion and posture
The solitary tract and nucleus are structures in the brainstem which carry and receive visceral sensation and taste from the facial, glossopharyngeal and vagus nerves
The posterior columns transmit which of the following structures?
A Temperature afferents
B Tendon stretch afferents
C Pain afferents
D Motor tracts
B
Explanation
Temperature and pain afferents are transmitted by the spino-thalamic tracts
Regarding the circle of Willis which of the following statements is correct?
A The internal carotid artery (ICA) gives off the ophthalmic artery
B The anterior cerebral artery (ACA) is the largest branch of the internal carotid artery (ICA)
C The posterior cerebral artery (PCA) is a branch of the internal carotid
D The middle cerebral artery (MCA) supplies the motor but not sensory cortex
A
Explanation
Posterior cerebral artery (PCA) is a branch of the basilar artery, the middle cerebral artery (MCA) is the largest branch which supplies both the sensory and motor cortex
Regarding the speech centres, which of the following statements is correct?
A Damage to Broca’s area produces motor aphasia
B Broca’s area is on the right side in most left handed people
C Damage to Wernicke’s area produces expressive dysphasia
D Wernicke’s area controls motor response
A
Explanation
Left hemisphere is dominant for language in over 95% of right handers and in over 60-70% of left-handers. Wernicke’s area is involved in the understanding of written and spoken language. Wernicke’s area produces receptive aphasia when damaged. Broca’s area is linked with speech production. (but new recent evidence demonstrates that Broca’s area also plays a significant role in language comprehension)
Regarding the ocular muscles, which of the following statements is correct?
A Combined action of superior rectus and inferior oblique causes vertical upward movement
B Superior rectus makes eye turn up and out
C Abducens paralysis makes eye turn down and out
D In trochlear paralysis, the eye cannot look upwards when turned out
A
Explanation
Paralysis of the abducens nerve, abduction of the eyeball is lost. Superior rectus adducts, elevates and medially rotates the eyeball. Trochlear paralysis leads to inability to abduct, depress and medially rotate the eyeball
Regarding the blood supply of the cerebral cortex, which of the following statements is true?
A The territory of the anterior cerebral artery (ACA) controls the contralateral leg, auditory and speech
B The territory of the middle cerebral artery (MCA) controls the ipsilateral arm, face and vision
C The territory of the anterior cerebral artery (ACA) controls the contralateral leg, micturition and defacation
D The territory of the posterior cerebral artery (PCA) controls ipsilateral vision
C
Explanation
The MCA area of cortical distribution is the motor and sensory area for the opposite half of the body, excluding perineum, leg and foot, along with the speach and auditory area. The PCA controls the visual area for the field of vision on the opposite side.
Which of the following statements is correct in relation to the midbrain?
A It contains the occulomotor nuclei
B It is supplied by the anterior and inferior cerebellar arteries
C It is largely in the middle cranial fossa
D It lies between the pons and the upper spinal cord
A
Explanation
Most of the midbrain lies in the posterior cranial fossa, with its upper part passing through the tentorial notch. The midbrain is supplied by the posterior cerebral and superior cerebellar arteries as they curl around the cerebral peduncle. The medulla oblongata lies between the pons and the spinal cord. The internal structure of the midbrain contains the occulomotor nucleus
Cerebrospinal fluid communicates with the subarachnoid space via which of the following?
A Tela Choroidia
B 3rd ventricle
C 4th ventricle
D Choroid plexus
C
Explanation
It communicates via the foramina of the lateral rescesses of the 4th ventricle in an area termed the cerebello-medullary cistern.
The foramina through which the CSF flows are two lateral apetures of Luschka (L for lateral) and in the median apeture of Magendie (M for median)
The motor nuclei of the facial nerve are found in which of the following areas?
A Cerebellum
B Midbrain
C Pons
D Medulla oblongata
C
Explanation
The motor part of the facial nerve arises form the facial nerve nucleus in the pons, which the sensory part arises from the nervus intermedius which emerges between the pons and the inferior cerebellar peduncle, near the vestibulo-cochlear nerve.
Cranial nerve nuclei: 1st 4 above the pons, 2nd 4 in the pons, 3rd 4 below the pons
Current Textbooks: I+II - forebrain III + IV - midbrain V - pons VI, VII, VIII - medulla-pons border IX, X, XII - medulla XI - spinal cord. Slightly different from what some previous textbooks have said.
A lumbar puncture needle passes through which correct series of layers to get CSF?
A Skin, subcutaneous tissue, supraspinous ligament, interspinous ligament, ligamentum flavum, dura, arachnoid
B Skin, subcutaneous tissue, ligamentum flavum, supraspinous ligament, interspinous ligament, dura, arachnoid
C Skin, subcutaneous tissue, supraspinous ligament, ligamentum flavum, interspinous ligament, dura, arachnoid
D Skin, subcutaneous tissue, interspinous ligament, ligamentum flavum, supraspinous ligament, dura, arachnoid
A
In relation to the anatomy of the lateral ventricles of the brain, which of the following statements is correct?
A The caudate nucleus is in the roof of the lateral ventricle
B The posterior horn is in the temporal lobe
C The choroid plexus extends into the canal
D The inferior horn is in the occipital lobe
C
Explanation
The caudate nucleus is in the floor of the lateral ventricle. The posterior horn extends into the occipital lobe and the inferior into the temporal lobe.
Note: the stem: “The choroid plexus extends into the canal”-is correct because all the others are incorrect. I have looked through LASTs and Moore and cannot find this statement. I have however left it as is.
More on the lateral ventricle and the choroid plexus:
Each lateral ventricle is a C-shaped cavity, lined with ependyma, lying wthin the cerebral hemisphere. It consists of the body of the ventricle and anterior, posterior and inferior horns.
The Choroid plexus (CP) is found in the lateral, 3rd and 4th ventricles. The CP consists of fringes of vascular pia mater (tela choroidea) covered by cuboidal epithelial cells. They are invaginated into the roofs of the 3rd and 4th ventricles and on the floor of the bodies and inferior horns of the lateral ventricles. The CP secrets cerebrospinal fluid.
Lasts anatomy
The choroid plexus of the lateral ventricles are large and highly vascular; this pair secretes the bulk of the cerebrospinal fluid. Each lateral ventricle opens into the third ventricle by the interventricular foramen, and the choroid plexus of the lateral ventricle is continuous through this foramen with the very small amount of plexus in the third ventricle.
The roof of the third ventricle is slack towards its posterior end and bulges back as the suprapineal recess. The whole length of the roof is invaginated by the pair of (small) choroid plexuses of the third ventricle, which hang down as slender fringes inside the cavity.
The choroid plexus of the fourth ventricle is a small T-shaped structure which indents the medullary part of the roof. It receives its blood supply from a branch of the posterior inferior cerebellar artery, which enters through the lateral aperture i=on each side and passes medially to meet its fellow, and the two turn down towards the median aperture making the vertical part of the T double. The veins form the plexus drain back into the occipital sinus
Which of the following regarding the cerebrospinal fluid is false?
A The net weight of the brain bathed in CSF is only 50g
B It is absorbed by the choroid plexuses
C 500-550 mls is produced daily
D It communicates between the 3rd and 4th ventricle via the cerebral aqueduct
B
,,
Explanation
CSF is secreted (at a rate of 500-550ml/day) by the choroid plexuses in the lateral, third and fourth ventricle. The main site of absorption of CSF is through the arachnoid granulations, especially those that protrude into the superior sagittal sinus and its lateral lacunae. CSF leaves the lateral ventricles and passes through the interventricular foramina into the third ventricle. From the third to the fourth ventricle via the cerebral aqueduct and then via the median and lateral apertures into the subarachnoid space. The brain weighs about 1400g in air, but in its “water bath of CSF” it has a net weight of only 50g. The buoyancy of the brain in the CSF permits it relatively flimsy attachments to suspend it very effectively.
Which of the following is true regarding brain herniation syndorme?
ATonsillar herniation is the most benign form
B Subfalcine herniation results in compression of the anterior cerebral artery
C Transtentorial herniation results in compression of the fourth cranial nerve
D Secondary haemorrhages do not occur following brain herniaton syndromes
B
Explanation
When the volume of the brain increases beyond the limit, permitted by the compression of veins and displacement of the cerebrospinal fluid, the pressure within the scull rises. Because the cranial vault is divided by rigid dural folds (the falx and the tentorium), localised expansion of the brain may cause it to be displaced in relation to theses partitions. If the expansion is severe, a brain herniation syndrome may occur.
Subfalcine (cingulate) herniation: occurs when unilateral or asymmetric expansion of a cerebral hemisphere displaces the cingulate gyrus under the falx cerebri. This may lead to compression of the anterior cerebral artery
Transtentorial (uncinate) herniation: occurs when the medial aspect of the temporal lobe is compressed against the free margin of the tentorium. The third cranial nerve can be compressed, resulting in pupillary dilation and impairment of ocular movements on the side of the lesion. The posterior cerebral artery may also be compressed resulting in ischaemia to the primary visual cortex. Progression of transtentorial herniation is often accompanied by haemorrhagic lesions in the midbrain or pons, called secondary brainstem (Duret) haemorrhages
Tonsillar herniation: displacement of the cerebellar tonsils through the foramen magnum. The type of herniation is life threatening because it compresses and compromises vital respiratory and cardiac centres in the medulla oblongata.
Extra: Monro-Kellie doctrine: Any change in the volume of the intracranial contents (e.g., a brain tumour, an accumulation of ventricular fluid caused by blockage of the cerebral aqueduct, or blood from a ruptured aneurysm) will be reflected by a change in intra-cranial pressure. This rule is called the Monro-Kellie doctrine, which states that the cranial cavity is a closed rigid box and that a change in the quantity of intracranial blood can occur only through the displacement or replacement of CSF
Which lobe of the brain is responsible for processing sense of smell?
A Occipital cortex
B Frontal lobe
C Temporal lobe
D Pituitary gland
C
Which nerve is responsible for the afferent pathway of the gag reflex
A CN VIII
B CN IX
C CN V
D CN VII
B
