Neuro TBL practice questions

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Questions and Answers

Which artery is the larger terminal branch of the internal carotid artery?

Basilar artery

Vertebral artery

Anterior cerebral artery

Middle cerebral artery (correct)

What region does the superior trunk of the middle cerebral artery primarily supply?

Lateral part of the occipital lobe

Primary motor cortex and primary somatosensory cortex (correct)

Visual cortex

Primary auditory cortex

Which structure is NOT supplied by the cortical branches of the middle cerebral artery?

Lateral surface of the cerebral hemisphere

Inferior surface of the frontal lobe

Peripheral rim of the cortex (correct)

Insula

Which segment of the middle cerebral artery extends from its origin to the bifurcation into superior and inferior trunks?

M1 segment Signup and view all the answers

What is the first part of the vertebral artery called?

Prevertebral Signup and view all the answers

What is the primary function of the anterior choroidal artery?

Supplying structures along the medial aspect of the temporal lobe Signup and view all the answers

Which artery connects the internal carotid artery to the proximal part of the posterior cerebral artery?

Posterior communicating artery Signup and view all the answers

The cortical branches of the anterior cerebral artery (ACA) primarily supply which areas?

Medial surface of the cerebral hemisphere Signup and view all the answers

Which of the following statements about the ophthalmic artery is accurate?

Enters the orbit with the optic nerve via the optic canal Signup and view all the answers

What does not describe the function of the anterior cerebral artery?

Arises from the posterior cerebral artery Signup and view all the answers

What is the primary function of the choroid plexus?

Regulates the constituents of cerebrospinal fluid (CSF) Signup and view all the answers

Which type of hydrocephalus is characterized by an obstruction in the ventricular system?

Noncommunicating (Obstructive) hydrocephalus Signup and view all the answers

What is a common clinical triad associated with normal pressure hydrocephalus in the elderly?

Gait difficulties, urinary incontinence, and mental decline Signup and view all the answers

Which of the following components is NOT part of the blood-brain barrier (BBB)?

Fenestrated capillary endothelium Signup and view all the answers

What primarily causes communicating hydrocephalus?

Impaired reabsorption of CSF Signup and view all the answers

Which statement about the blood-CSF barrier is correct?

It is located in the choroid plexus without tight junctions Signup and view all the answers

What happens to the ventricles in noncommunicating hydrocephalus?

They enlarge proximal to the obstruction Signup and view all the answers

What is the primary complication when delivering drugs into the CNS?

Existence of the blood-brain barrier Signup and view all the answers

Which arteries does the internal carotid artery become after exiting the cavernous sinus?

Anterior and middle cerebral arteries Signup and view all the answers

What is the characteristic feature of normal pressure hydrocephalus?

CSF pressure is not elevated Signup and view all the answers

What is the primary artery that curves around the medulla to supply the inferior cerebellar surface?

Posterior inferior cerebellar artery Signup and view all the answers

Which part of the brain does the basilar artery primarily supply?

Superior surface of the cerebellum Signup and view all the answers

What kind of fibers are responsible for transmitting non-discriminative touch, pain, and temperature sensations?

C fibers Signup and view all the answers

What is the primary role of the anterior spinal artery?

Provides blood to the anterior two-thirds of the spinal cord Signup and view all the answers

Which artery supplies blood to the primary visual cortex?

Posterior cerebral artery Signup and view all the answers

Where do the 2nd order neurons of the dorsal column-medial lemniscus pathway synapse?

Gracile and cuneate nuclei Signup and view all the answers

What type of sensation is carried by the anterolateral system?

Fast pain and temperature Signup and view all the answers

Which artery is often associated with intra-cerebral hemorrhage in hypertensive patients?

Lenticulostriate arteries Signup and view all the answers

What is the main function of the primary somatosensory cortex?

Processing tactile and pain sensations Signup and view all the answers

Which structure receives blood supply from the posterior communicating artery?

Posterior part of the thalamus Signup and view all the answers

What is the effect of lesions in the primary somatosensory cortex?

Impairment of fine aspects of somatic sensation Signup and view all the answers

Which part of the spinal cord receives reinforcement from spinal medullary arteries?

Upper lumbar region Signup and view all the answers

What role do perforating branches serve in the cerebral circulation?

They supply deeply located structures Signup and view all the answers

What connects the anterior and posterior circulation of the brain?

Circle of Willis Signup and view all the answers

Which of the following statements about the dorsal column-medial lemniscus pathway is correct?

It is organized somatotopically. Signup and view all the answers

Study Notes

Meninges & Ventricular System

Choroid Plexus: A network of capillaries that produces and regulates cerebrospinal fluid (CSF).
Hydrocephalus: A condition characterized by the abnormal accumulation of CSF, leading to the dilation of ventricles or subarachnoid space.
- Noncommunicating (Obstructive) Hydrocephalus: Obstruction of CSF flow within the ventricular system (interventricular foramen, cerebral aqueduct, or medial/lateral apertures of the 4th ventricle).
  - Causes enlargement of ventricles proximal to the obstruction.
- Communicating Hydrocephalus: Impaired CSF reabsorption in arachnoid granulations or excessive CSF production.
  - All ventricles and subarachnoid space are dilated.
- Normal Pressure Hydrocephalus: Seen in elderly, characterized by a triad of gait difficulties, urinary incontinence, and mental decline (dementia).
  - CSF pressure is not elevated, likely due to impaired CSF reabsorption.

Blood Brain Barrier (BBB) & Blood-CSF Barrier

BBB: Prevents large molecules from entering the CNS.
- It is composed of: endothelial cells with tight junctions, astrocytes with perivascular end-feet, and capillary basement membrane.
Blood-CSF Barrier: Located in the choroid plexus, where the endothelial cells lining the capillary wall have fenestrations.
- Large molecules can pass from blood through these fenestrations.
Circumventricular Organs: Areas in the brain that lack the BBB, enabling access to the bloodstream for their specific functions.

Arterial Supply of the CNS

Internal Carotid Artery: Supplies blood to the anterior and middle regions of the brain.
- Branches:
  - Ophthalmic Artery: Supplies the orbit, nasal cavity, paranasal sinuses, and scalp.
  - Anterior Choroidal Artery: Supplies the choroid plexus, temporal lobe structures, and the internal capsule.
  - Posterior Communicating Artery: Connects the anterior and posterior circulations.
  - Anterior Cerebral Artery (ACA):
    - A1 segment: Runs above the optic nerve, supplying the medial surface of the brain, including the motor and sensory cortices for the contralateral lower limb.
  - Middle Cerebral Artery (MCA):
    - M1 segment: Bifurcates into superior and inferior trunks, supplying the lateral surface of the brain, including motor and sensory cortices for the face and upper limb, as well as speech areas (Broca's and Wernicke's).
Vertebral Artery: Originates from the subclavian artery and supplies the posterior regions of the brain.

Vertebral Artery

The vertebral artery originates from the subclavian artery
Passes through the transverse foramina of the cervical vertebrae (C6-C1)
Enters the cranial cavity through the foramen magnum
Joins with the vertebral artery from the opposite side to form the basilar artery at the medullopontine sulcus

Branches of Vertebral Artery

Posterior Inferior Cerebellar Artery (PICA)
- Largest branch of the vertebral artery
- Supplies the posterolateral part of the medulla oblongata, the choroid plexus of the fourth ventricle, and the posterior and medial parts of the inferior surface of the cerebellum.
Posterior Spinal Artery
- Supplies the posterior part of the spinal cord
Anterior Spinal Artery
- Supplies the anterior two-thirds of the spinal cord

Basilar Artery

Runs in the basilar sulcus of the pons from the medullopontine sulcus to the pons-midbrain junction
Terminates by dividing into two posterior cerebral arteries
Supplies the pons, cerebellum, and midbrain

Branches of Basilar Artery

Pontine Arteries
- Supply the pons
Anterior Inferior Cerebellar Artery (AICA)
- Supplies the anterior and lateral parts of the inferior surface of the cerebellum, the lower part of the middle cerebellar peduncle, the choroid plexus of the fourth ventricle, and sends slender twigs to the upper medulla and lower pons.
Labyrinthine (Internal Auditory) Artery
- Enters the internal acoustic meatus with cranial nerves VII and VIII to supply the internal ear.
Superior Cerebellar Artery (SCA)
- Passes laterally, just inferior to the oculomotor nerve
- Wraps around the brainstem, under the tentorium cerebelli
- Supplies the superior surface of the cerebellum, including most of the cerebellar nuclei.
- Its proximal part gives branches to the upper pons, the upper part of the middle cerebellar peduncle, the superior cerebellar peduncle, and the inferior colliculus of the midbrain.
Posterior Cerebral Artery (PCA)
- Passes laterally, just above the oculomotor nerve
- Continues around the midbrain and joins the medial aspect of the temporal lobe
- Supplies the inferior and medial surfaces of the temporal and occipital lobe, including the primary visual cortex, the splenium of the corpus callosum, and a strip of cortex on the lateral surface.

Cerebral Arterial Circle (Circle of Willis)

Consists of larger cerebral vessels and their interconnections on the ventral surface of the brain.
Components:
- Internal carotid artery
- Anterior communicating artery
- Posterior communicating artery
- Posterior cerebral artery
- Anterior cerebral artery
May serve as a potential vascular shunt, assisting in the development of collateral circulation if one of the proximal vessels is occluded.

Perforating (Central) Branches

Small arteries that originate from the large arteries on the base of the brain to supply deeply located structures of the cerebral hemispheres and diencephalon and parts of the midbrain.
Groups:
- Anteromedial: Supply the optic chiasm and anterior part of the hypothalamus
- Anterolateral: Supply most of the caudate, putamen, globus pallidus, and internal capsule.
  - Lenticulostriate arteries are the most common site of intra-cerebral hemorrhage in hypertensive individuals.
- Posteromedial: Supply the middle and posterior regions of the hypothalamus, subthalamus, anterior part of the thalamus, and medial parts of the midbrain.
- Posterolateral: Supply the posterior part of the thalamus, choroid plexus of the lateral and third ventricles, and posterior and lateral midbrain.

Arterial Supply of the Spinal Cord

The spinal cord is supplied by one anterior and two posterior spinal arteries.
Blood received by spinal arteries from vertebral arteries is sufficient only to supply the upper cervical segments of the spinal cord.
Spinal arteries are reinforced at intervals by spinal branches of segmental arteries.
- Spinal branches enter the vertebral canal via intervertebral foramina and give off anterior and posterior radicular arteries and anterior and posterior spinal medullary arteries.
Anterior and posterior radicular arteries supply the ventral and dorsal roots of spinal nerves and are present at all spinal cord levels.
Anterior and posterior spinal medullary arteries reinforce the anterior and posterior spinal arteries, but are not present at all spinal cord levels.
The largest spinal medullary artery (Adamkiewicz) joins the anterior spinal artery in the upper lumbar region, most frequently on the left side.
- It may provide the entire arterial supply to the lumbosacral spinal cord.
Branches of the anterior spinal artery supply the anterior two-thirds of the spinal cord: anterior horn, intermediate zone of gray matter, basal part of the posterior horn, anterior and lateral funiculi.
Branches of the posterior spinal artery supply the posterior one-third of the spinal cord: posterior horn and posterior funiculus.

Somatosensory System

General senses:
- Touch (discriminative & non-discriminative)
- Vibration
- Proprioception (limb position & motion)
- Pain
- Temperature
Dorsal Column-Medial Lemniscus Pathway
- Carries discriminative touch, vibration, and proprioception from the trunk and limbs.
- Consists of three neurons:
  - First-order neuron: Located in the sensory ganglion (dorsal root ganglia or spinal nerves, trigeminal ganglion)
  - Second-order neuron: Located in the nucleus of the spinal cord or brainstem.
    - The axon crosses to the opposite side and then ascends to the thalamus.
  - Third-order neuron: Located in the thalamus (VPL or VPM nuclei).
    - Projects to the cerebral cortex which is the primary somatosensory cortex
Anterolateral System (Spinothalamic Tract)
- Carries non-discriminative touch, pain, and temperature information from the trunk and limbs.
- Direct spinothalamic pathway (neospinothalamic pathway): Carries fast pain (sharp, well-localized)
- Indirect spinothalamic pathway (paleospinothalamic pathway): Carries slow pain (dull, burning, ache)
Other fibers in the anterolateral system:
- Spinomesencephalic fibers: Extend from the spinal cord to the periaqueductal gray matter of the midbrain and play a role in intrinsic pain control mechanisms.
- Spinoreticular fibers: Convey pain signals to the reticular formation.
- Reticulothalamic fibers: Convey pain signals from the reticular formation to the thalamus.
The hypothalamus and limbic system structures receive pain information directly or indirectly, which is important for emotional and autonomic responses to nociceptive stimuli.

Primary Somatosensory Cortex (SI)

Location: Postcentral gyrus and posterior paracentral lobule (Brodmann areas 3, 1, 2)
Contains a somatotopic representation of the contralateral body in an upside-down fashion ("little man")
The size of the cortical area associated with a particular region of the body depends on the sensitivity of the body region and not the size of the region.
- Hands and lips have a high density of receptors, resulting in large cortical representation
- The back has a small density of receptors, resulting in small cortical representation
Lesions affecting the primary somatosensory cortex can cause impairment of fine aspects of somatic sensations (difficulty judging the exact location or intensity of a stimulus) and a deficit in the sense of position and movement of the body parts. However, this does not abolish tactile sensation or sensation of pain.
Supplied by the middle cerebral artery (MCA) and anterior cerebral artery (ACA)
- Vascular lesions in the MCA can lead to sensory loss in the contralateral upper limb and face.
- Vascular lesions in the ACA can lead to sensory loss in the contralateral lower limb.

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