Neuroanatomy Review Questions
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Questions and Answers

Damage to which lobe would most likely result in difficulties with understanding spoken language?

  • Occipital Lobe
  • Frontal Lobe
  • Parietal Lobe
  • Temporal Lobe (correct)

Which of the following best describes the composition and location of gray matter within the central nervous system (CNS)?

  • Primarily composed of myelinated axons, found in the deep nuclei only.
  • Primarily composed of nerve cell bodies, found in the cortical layer and deep nuclei. (correct)
  • Primarily composed of glial cells, evenly distributed throughout the CNS.
  • Primarily composed of fiber tracts, connecting different parts of the CNS.

The anterior spinal artery supplies which portion of the spinal cord and originates from which arteries?

  • The lateral columns; originating from the posterior inferior cerebellar arteries.
  • The posterior one-third; originating from the internal carotid arteries.
  • The anterior two-thirds; originating from the vertebral arteries. (correct)
  • The entire spinal cord; originating from the basilar artery.

What is the primary function of the choroid plexus, and in which structures is it located within the brain?

<p>Secretion of cerebrospinal fluid (CSF); located in all four ventricles. (D)</p> Signup and view all the answers

Which of the following accurately describes the flow of cerebrospinal fluid (CSF) from its production site to its reabsorption point?

<p>Lateral ventricles → third ventricle → fourth ventricle → subarachnoid space → arachnoid granulations. (A)</p> Signup and view all the answers

In a patient experiencing increased intracranial pressure due to impaired CSF reabsorption, which of the following structures is most likely to be malfunctioning?

<p>The arachnoid granulations. (D)</p> Signup and view all the answers

A patient presents with a lesion affecting the posterior inferior cerebellar artery (PICA). Which of the following neurological deficits is most likely to be observed, considering the PICA's area of supply?

<p>Sensory deficits in the posterior one-third of the spinal cord. (D)</p> Signup and view all the answers

Which statement accurately describes the role of cerebrospinal fluid (CSF) in both normal and pathological conditions within the central nervous system?

<p>CSF cushions the brain and spinal cord under normal conditions; disruptions in its circulation can lead to hydrocephalus. (A)</p> Signup and view all the answers

A patient presents with loss of pain and temperature sensation on the left side of their body. Assuming a single lesion, where is the most likely location of this lesion in the spinal cord?

<p>Right spinothalamic tract (D)</p> Signup and view all the answers

A patient has difficulty with fine motor movements and exhibits increased muscle tone on the right side of their body following a spinal cord injury. Which spinal tract is most likely affected?

<p>Right lateral corticospinal tract (B)</p> Signup and view all the answers

Damage to the anterior spinal artery can lead to anterior cord syndrome. Which set of symptoms would most likely be observed in a patient with this syndrome?

<p>Loss of pain/temperature sensation and flaccid paraplegia. (C)</p> Signup and view all the answers

A patient presents with loss of discriminative touch and proprioception on the right side of their body. Where is the most likely location of the lesion?

<p>Right posterior column (A)</p> Signup and view all the answers

A patient exhibits ipsilateral loss of motor function, ipsilateral loss of discriminative touch and proprioception, and contralateral loss of pain and temperature sensation. Which condition is most likely?

<p>Brown-Séquard syndrome (B)</p> Signup and view all the answers

Following a traumatic injury, a patient develops a syrinx in the central canal of the spinal cord. Which of the following is the mechanism of this condition?

<p>Widening of the central canal (D)</p> Signup and view all the answers

A clinician assesses a patient with a spinal cord injury and notes spasticity and brisk deep tendon reflexes below the level of the lesion. What does this indicate about the affected corticospinal tract?

<p>Upper motor neuron (UMN) damage only (C)</p> Signup and view all the answers

Which component of the nervous system connects the brain and spinal cord to the periphery and visceral tissues?

<p>Peripheral nervous system (PNS) (B)</p> Signup and view all the answers

During the relative refractory period of a neuron, what is the primary factor contributing to the higher threshold required to initiate an action potential?

<p>Most Na+ channels have reset, but some K+ channels are still open, hyperpolarizing the membrane. (D)</p> Signup and view all the answers

Which of the following comparisons accurately describes the difference between continuous and saltatory conduction?

<p>Saltatory conduction occurs in myelinated axons, allowing depolarization to 'jump' between nodes of Ranvier, increasing speed. (D)</p> Signup and view all the answers

Which of the following is a key difference between electrical and chemical synapses?

<p>Electrical synapses involve a physical connection between neurons via gap junctions, allowing direct ion flow. (D)</p> Signup and view all the answers

If a drug selectively blocked metabotropic glutamate receptors (mGluRs) in the CNS, what would be the most likely direct effect?

<p>Reduced excitatory neurotransmission due to the blockage of a G-protein coupled glutamate receptor. (A)</p> Signup and view all the answers

How do GABAA receptors mediate their inhibitory effects in the CNS?

<p>By increasing Cl- influx, leading to hyperpolarization. (A)</p> Signup and view all the answers

What is the primary mechanism by which acetylcholinesterase (AChE) terminates signaling at cholinergic synapses?

<p>By degrading acetylcholine into inactive metabolites, thus reducing receptor activation. (B)</p> Signup and view all the answers

Which of the following describes a primary role of astrocytes in neuronal function?

<p>Astrocytes synthesize and provide glutamine, a precursor for glutamate, to neurons. (D)</p> Signup and view all the answers

Which of the following best describes the concept of temporospatial summation in synaptic transmission?

<p>The integration of synaptic potentials arriving at different times and locations on the postsynaptic neuron. (C)</p> Signup and view all the answers

What directly triggers the release of acetylcholine (ACh) into the synaptic cleft at the neuromuscular junction?

<p>The increase in intracellular Ca2+ in the axon terminal. (A)</p> Signup and view all the answers

Which component of the neuromuscular junction is responsible for propagating the action potential to the muscle fiber?

<p>The axonal endings of the motor neuron. (B)</p> Signup and view all the answers

What is the immediate effect of acetylcholine (ACh) binding to its receptors on the skeletal muscle membrane?

<p>Influx of Na+ into the muscle fiber, causing an endplate potential. (B)</p> Signup and view all the answers

Which of the following best describes the role of voltage-gated calcium channels at the neuromuscular junction?

<p>They allow calcium to enter the axon terminal, triggering neurotransmitter release. (B)</p> Signup and view all the answers

What is the endplate potential (EPP) and how is it generated?

<p>A graded potential from Na+ influx; triggered by ACh binding. (D)</p> Signup and view all the answers

Which of the following describes the sequence of events at the neuromuscular junction (NMJ) that leads to muscle contraction?

<p>Action potential -&gt; ACh release -&gt; Na+ influx -&gt; Ca2+ release from sarcoplasmic reticulum (D)</p> Signup and view all the answers

Which of the following does NOT directly participate in signal transduction at the neuromuscular junction (NMJ)?

<p>Potassium ions (K+) (A)</p> Signup and view all the answers

What is the primary function of the neuromuscular junction (NMJ)?

<p>To facilitate communication between a motor neuron. (A)</p> Signup and view all the answers

A patient presents with a lesion affecting the anterior white commissure of the spinal cord. Which sensory deficit would you most likely observe?

<p>Loss of pain and temperature sensation on the contralateral side. (B)</p> Signup and view all the answers

A stroke involving the caudal medulla affects the medial lemniscal pathway. What sensory deficits would result from this?

<p>Loss of discriminative touch and proprioception on the contralateral side. (D)</p> Signup and view all the answers

Which spinal cord tract plays a crucial role in coordinating movement, particularly by facilitating flexor muscle activity in the upper limbs and originating from the red nucleus?

<p>Rubrospinal Tract (A)</p> Signup and view all the answers

A patient exhibits loss of fine touch and proprioception in the left leg. Imaging reveals a spinal cord lesion. Which specific region of the spinal cord is most likely affected?

<p>Left posterior column (D)</p> Signup and view all the answers

Damage to the anterior corticospinal tract in the spinal cord would most likely result in:

<p>Impaired posture maintenance during gait. (A)</p> Signup and view all the answers

A patient has a lesion in the spinal cord that results in the loss of pain and temperature sensation a few segments below the level of the lesion on the opposite side of the body. Which of the following explains this phenomenon?

<p>Pain and temperature fibers ascend a few segments in the Lissauer's tract before synapsing. (C)</p> Signup and view all the answers

Compared to the spinothalamic tract, what is a key difference in the origin and termination of the Dorsal Column-Medial Lemniscal Pathway?

<p>The DC-ML pathway originates in sensory receptors and terminates in the thalamus. (C)</p> Signup and view all the answers

How does the location of the fasciculus gracilis and fasciculus cuneatus within the posterior columns relate to the body region they serve?

<p>Fasciculus gracilis carries information from the lower body and is located medially. (B)</p> Signup and view all the answers

Which of the following accurately describes the path of the rubrospinal tract?

<p>Neuron from red nucleus → Lower Motor Neuron in spinal cord (B)</p> Signup and view all the answers

What is the primary role of the alpha motor neuron (α-motor neuron)?

<p>Directly innervating and contracting skeletal muscle fibers. (B)</p> Signup and view all the answers

During the myotatic reflex, which type of sensory receptor is primarily responsible for detecting changes in muscle length?

<p>Muscle spindles (B)</p> Signup and view all the answers

What is the functional significance of reciprocal innervation in the myotatic reflex?

<p>To prevent resistance from opposing muscles during the reflex. (C)</p> Signup and view all the answers

Why is the myotatic reflex classified as a monosynaptic reflex?

<p>Because the sensory and motor neurons synapse directly. (D)</p> Signup and view all the answers

An individual with damage to their Ia interneurons would likely exhibit which of the following during a patellar tendon tap?

<p>Simultaneous contraction of both the quadriceps and hamstring muscles. (A)</p> Signup and view all the answers

Where are Golgi tendon organs (GTOs) located, and what do they primarily monitor?

<p>At the musculotendinous junction; monitor muscle tension. (D)</p> Signup and view all the answers

How does the inverse myotatic reflex (Golgi tendon reflex) protect muscles from injury?

<p>By inhibiting muscle contraction when excessive tension is detected. (B)</p> Signup and view all the answers

Flashcards

Temporal Lobe

Processes auditory information, language comprehension, memory formation, and facial/object recognition.

Occipital Lobe

The primary visual cortex responsible for processing visual information.

Limbic Lobe

Involved in emotional regulation.

Gray Matter

Nerve cell bodies found in the cortical layer and deep nuclei.

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White Matter

Fiber tracts (axons) that connect different parts of the CNS, mostly myelinated.

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Anterior Spinal Artery

Supplies the anterior two-thirds of the spinal cord.

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Choroid Plexus

Produces cerebrospinal fluid (CSF) and is located in all four ventricles.

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Role of CSF

Cushions the brain/spinal cord, removes waste, maintains stable chemical environment.

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Relative Refractory Period

Period where a neuron requires a stronger stimulus to fire, due to some Na+ channels still being inactive.

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Saltatory Conduction

The 'jumping' of depolarization along a myelinated axon from one node of Ranvier to the next, speeding up transmission.

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Synapse

A functional junction between two neurons or a neuron and a target cell, where signals are transmitted.

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Neurotransmitter

A chemical messenger that transmits signals across a chemical synapse.

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Glutamate

The most common excitatory neurotransmitter in the CNS, acting on NMDA, AMPA, kainate, and mGluRs receptors.

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GABA and Glycine

Key inhibitory neurotransmitters in the CNS, causing hyperpolarization.

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Acetylcholine

A neurotransmitter present in the PNS, CNS, and neuromuscular junctions. Can be ionotropic or metabotropic.

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Biogenic Amines

Includes catecholamines (dopamine, norepinephrine, epinephrine), histamine, and serotonin.

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Lateral Corticospinal Tract

Carries motor information; lesion results in ipsilateral motor function loss, spasticity, and brisk reflexes.

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Spinothalamic Tract

Located in the anterior lateral column; carries pain and temperature sensation from the contralateral side.

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Posterior Column

Carries discriminative touch and proprioception from the ipsilateral side of the body.

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Neuromuscular Junction (NMJ)

The specialized synapse where motor neurons communicate with skeletal muscle fibers to initiate muscle contraction.

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Anterior Spinal Cord Syndrome

Results from anterior spinal artery disruption; affects spinothalamic and corticospinal tracts, and anterior horn cells.

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NMJ Components

The axonal endings of the motor neuron, the postsynaptic skeletal muscle membrane, and associated Schwann cells.

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Syringomyelia

Widening of the central canal within the spinal cord, often post-trauma.

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ACh Release

An action potential triggers Ca2+ influx, causing vesicles to release acetylcholine (ACh) into the synaptic cleft.

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Brown-Séquard Syndrome

Hemicord injury causing ipsilateral motor loss, touch/proprioception loss, and contralateral pain/temperature loss.

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Endplate Potential

ACh binds to receptors on the muscle membrane, leading to Na+ influx and an excitatory postsynaptic potential (EPSP).

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Ipsilateral Motor Loss

Loss of motor function on the same side as the lesion.

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Peripheral Nervous System (PNS)

Peripheral nerves consist of cranial and spinal nerves, linking the CNS to the periphery and visceral tissues.

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Ca2+ and Contraction

Voltage-gated calcium channels open in the sarcoplasmic reticulum, triggering muscle contraction.

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Calcium Influx

Depolarization of the axon terminal that causes voltage-gated Ca2+ channels to open, leading to an influx of Ca2+ into the axon terminal.

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Neurotransmitter Release

Synaptic vesicles fuse with the presynaptic membrane and release the neurotransmitter acetylcholine (ACh) into the synaptic cleft.

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Receptor Binding

ACh diffuses across the synaptic cleft and binds to ACh receptors on the skeletal muscle membrane. These receptors are ligand-gated ion channels.

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Anterior Corticospinal Tract function

Controls posture during upright gait; mostly bilateral innervation to lower motor neurons.

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Spinothalamic Tract function

Carries pain and temperature information from the body to the brain.

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Spinothalamic Tract lesion effect

Loss of pain and temperature sensation on the opposite side of the body.

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DC-Medial Lemniscal Pathway function

Carries discriminative touch, vibration, and proprioception information.

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DC-Medial Lemniscal Pathway lesion effect

Loss of discriminative touch and proprioception on the same side of the body.

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Rubrospinal Tract function

Coordinates movement between LMN circuits, the cerebellum, and the cortex.

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Rubrospinal Tract specifics

Facilitates flexor muscle activity in the upper limbs, inhibits extensors.

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Dorsal Column-Medial Lemniscal Pathway neuron count

Primary sensory neuron → Secondary neuron in medulla → Tertiary neuron in thalamus.

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Rubrospinal Tract

A motor pathway with 2 neurons: one from the red nucleus to a lower motor neuron in the spinal cord.

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Alpha Motor Neuron

A lower motor neuron in the ventral horn of the spinal cord. It directly innervates skeletal muscle fibers.

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Myotatic Reflex

Reflex initiated by stretching a muscle, causing the same muscle to contract. It maintains posture.

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Muscle Spindles

Sensory receptors within the muscle body that monitor the length of muscle.

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Ia Nerve Afferents

Afferent fibers that carry sensory signals from muscle spindles to the spinal cord.

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Reciprocal Innervation

The circuit where one muscle contracts and its opposing muscle relaxes. It is critical for coordinated movement.

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Monosynaptic

The myotatic reflex involves a direct synapse between the sensory and motor neuron.

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Inverse Myotatic Reflex

Reflex activated by muscle contraction and Golgi tendon organs (GTOs) being stretched.

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Study Notes

Cellular Components of the Nervous System

  • Neurons are essential to the nervous system.
  • They feature a functional organization with the soma, dendrites, and axon.
  • The axon may have a myelin sheath.
  • Neurons come in multipolar, pseudounipolar, and bipolar types.
  • Synapses can be axodendritic, axosomatic, or axoaxonic.
  • Axodendritic synapses link axons to dendrites, enabling temporal-spatial summation.
  • Glial cells include: astroglia, oligodendroglia, Schwann cells, microglia, polydendrocytes, and ependymal cells.
  • Astroglia includes astrocytes and Müller cells and is part of the blood-brain barrier and tripartite synapses.
  • Astrocytes are fibrous (in white matter) or protoplasmic (in gray matter).
  • Oligodendroglia is myelinating cells in the central nervous system.
  • Schwann cells are myelinating cells in the peripheral nervous system.
  • Microglia removes debris and presents antigens as immune cells.
  • Polydendrocytes are stem cells generating glia and neurons, implicated in demyelinating disorders and network cross-talk.
  • Ependymal cells are epithelial cells lining ventricles that separate cerebrospinal fluid (CSF) from the neuropil; also, they help produce CSF via the choroid plexus.
  • The components of the blood-brain barrier include endothelial cells with tight junctions and astrocyte processes to maintain homeostasis, and it facilitates substance transport via diffusion or active transport.

Basic Neurophysiology

  • Neurophysiology studies ion movements across membranes for signal transduction, action potentials, and neurotransmitter action.
  • Ion movement across membranes plays a crucial role in neurophysiology.
  • An action potential is depolarization moving down the axon.
  • It starts when membrane voltage drops to a threshold, opening voltage-activated ion channels for Na+ inflow to allow flow into the neuron.
  • Action potentials show an all-or-none response and self-propagate.
  • Repolarization follows behind the action potential.
  • Axons enter an absolute refractory period that prevents additional firing.
  • After sufficient Na+ resets, there's a relative refractory period that needs a higher threshold.
  • Action potential speed relies on axon diameter and myelination.
  • Continuous conduction involves the total axon membrane (unmyelinated neurons).
  • Saltatory conduction (myelinated neurons) makes depolarization jump between nodes of Ranvier, accelerating it.
  • Synaptic transmission can be electrical or chemical.
  • A synapse is a functioning connection between two neurons.
  • Electrical synapses use gap junctions.
  • Chemical synapses use vesicles.
  • Synaptic signal transduction uses inhibitory (IPSP) and excitatory postsynaptic potentials (EPSP).
  • Temporospatial summation effectively evokes potential.
  • Receptors are either ionotropic or metabotropic.

Main Neurotransmitters

  • Neurotransmitters include glutamate, GABA, glycine, acetylcholine, biogenic amines, ATP, and neuropeptides.
  • Glutamate is the main excitatory neurotransmitter in the CNS, working on NMDA, AMPA, kainate, and mGluRs receptors.
  • Its precursor is glutamine, which is supplied by astrocytes.
  • GABA and glycine serve as chief inhibitory neurotransmitters in the CNS.
  • GABA links to ionotropic GABAA and GABAC receptors, causing Cl- influx and hyperpolarization.
  • The metabotropic GABAB receptor activates K+ channels and blocks Ca2+ channels, thereby hyperpolarizing.
  • Acetylcholine is within the peripheral nervous system (PNS), CNS, and neuromuscular junctions.
  • Nicotinic acetylcholine receptors are ionotropic, while muscarinic acetylcholine receptors are metabotropic.
  • Acetylcholinesterase deactivates acetylcholine.
  • Biogenic amines: This class includes catecholamines (dopamine, norepinephrine, epinephrine), histamine, and serotonin.
  • ATP acts as an energy carrier, cotransmitter, and neuromodulator.
  • Neuropeptides: These encompass substance P, metenkephalin, opioids, and corticotropin-releasing hormone.

General Organization and Major Anatomical Structures of the CNS

  • The brain has the forebrain, brainstem, and hindbrain.
  • The forebrain includes the telencephalon (cerebrum and basal ganglia) and the diencephalon (thalamus, hypothalamus, and subthalamus), and the thalamus is a gateway to the cerebral cortex.
  • The hypothalamus manages autonomic, endocrine functions, plus impacts behavior, whereas the subthalamus changes voluntary motor activity.
  • The brainstem contains the midbrain.
  • Hindbrain has the medulla, pons, and cerebellum.
  • The spinal cord is divided into cervical, thoracic, lumbar, sacral, and coccygeal areas.
  • Meninges cover both the brain and spinal cord and have three layers including: dura mater, arachnoid mater, and pia mater.

Lobes of the Brain and Important Landmarks

  • The primary lobes of the brain include frontal, parietal, temporal, occipital, and limbic lobes.
  • The longitudinal fissure separates the cerebral hemispheres.
  • The central sulcus divides the frontal from parietal lobes.
  • The lateral fissure (Sylvius) separates the frontal and parietal lobes from the temporal lobe.
  • The parieto-occipital sulcus sits on the medial surface, splitting the occipital from parietal and temporal lobes.
  • The calcarine fissure is on the medial surface of the occipital lobe
  • Gyrus: This is a ridge on the cerebral cortex.
  • Sulcus: A valley between gyri on the cerebrl cortex.
  • Deep sulcus: AKA as a fissure.
  • Precentral gyrus: It is located anterior to the central sulcus, and happens to be the primary motor area.
  • Postcentral gyrus: It is located posterior to the central sulcus, and happens to be the primary somatosensory area.
  • Superior temporal gyrus: It is involved with higher-level auditory processing, including speech and sound localization.
  • Parahippocampal gyrus: Critical for memory formation, spatial orientation, and scene recognition.
  • Fusiform gyrus: It is strongly involved in facial recognition.
  • Cingulate gyrus: It relates to motivation, spotting mistakes, and making decisions.

Functions of Different Lobes

  • Frontal lobe: This lobe controls voluntary movement, plans and coordinates complex actions, enables language production/speech, supports high-level cognitive functions/emotional processes, and promotes decision-making/social behavior.
  • Parietal lobe: It interprets sensory data relating to touch, pressure, warmth, and discomfort, in addition to involving with language and reading.
  • Temporal lobe: It processes auditory data, and supports language comprehension/memory, plus facial/object recognition.
  • Occipital lobe: It forms the primary visual cortex.
  • Limbic lobe: It is essential for emotional regulation.

Arrangements of Gray and White Matter

  • Gray matter contains nerve cell bodies and occurs in the cortical layer and certain deep nuclei.
  • White matter has fiber tracts (axons) joining distinct portions of the CNS, most of which is myelinated.

Structure of the Blood-Brain Barrier (BBB)

  • The blood-brain barrier (BBB) is a selective barrier that protects the brain from harmful substances while allowing essential nutrients to enter.
  • It's built from tight junctions between endothelial cells, astrocyte end-feet surrounding blood vessels, and a thick basement membrane.
  • The BBB stops large molecules, pathogens, and toxins from getting through, so neuronal function stays optimal.

Vessels that Supply the CNS

  • Internal Carotid Artery (ICA): Features cervical, petrous, cavernous, and cerebral segments.
  • Vertebral-Basilar Arterial system: The spinal artery forms through branches stemming off vertebral arteries, giving a blood supply to the spinal cord's anterior two-thirds.
  • Posterior spinal arteries are sourced from the vertebral arteries or else from posterior inferior cerebellar arteries (PICAs), so delivering a supplement of blood for that posterior one-third on spinal cord.

Anatomy and function of the Choroid Plexus

  • The choroid plexus produces cerebrospinal fluid (CSF) across all four ventricles; the choroid epithelium is made of ependymal cells that morph into cuboidal epithelium, along with capillaries.

Circulation of Cerebral Spinal Fluid (CSF)

  • CSF secreted from choroid plexus travels out ventricles, starting from the lateral and moving in sequence through that third, then on into the ventricle, and finally gets in CSF filling inside that narrow central canal through getting exited from this ventricle past foramina( Luschka/Magendie).
  • CSF passes though the subarachnoid area right to arachnoid granulations allowing itself drained back into the bloodstream through this passage or villi, which goes through where the superior sagittal sinus lies within itself.

Somatotopy and Blood Supply Occlusions

  • Somatotopy: Each part on something you touch links back onto some matching spot located inside your central system.
  • Impaired blood supply with blockages could further bring about focal deficits based precisely for what brain location ends up impacted plus their subsequent topographical layout mapping.
  • Primary motor cortex lesions: If precentral cortex areas get broken, contralateral muscle malfunction or weakness happen most commonly as outcome scenarios.
  • Primary sensory lesions: If post central gyrus get broken, contralateral muscle malfunction or weakness happen most commonly as outcome scenarios.

Circle of Willis

  • The Circle of Willis is an arterial anastomosis that connects the internal carotid and vertebral-basilar systems.
  • It consists of anterior communicating artery that connects the two ACAs, while the posterior communicating arteries connects ICAs to PCAs to ensure good blood supply to the brain.

Spinal Cord Functional Anatomy

  • Spinal Meninges have three layers like what is happening with someone's human counterparts: the dura mater situated furthest from where injury could take place right on through protective barrier and where arachnoid follows next which further houses liquid called ‘cerebral’, then there is one layer positioned down quite close by, which shields with that too.
  • White Matter has axons arranged into groups otherwise called "tracts" mostly, and it occupies area outside around those regions filled solely via grey matter,
  • Gray Matter occurs towards cord's center , encompassing neurons inside all throughout central structure
  • Rexed's Laminae consist mostly grey sections grouped alongside.
  • Lamina II manages a level including sense around what some might refer in order as being ‘painful,’.
  • Blood Supply: Anterior spinal artery giving blood on to this lower surface about 66%, while posterior ones assist about 33% to keep on well maintained health.
  • Adamkiewicz blood carrier: If this particular artery sustains injuries this makes paraplegia.

Motor Components of the Spinal Cord

  • Motor information leaves the spinal cord by way of anterior roots.
  • Lower motor neurons (LMNs) exist from the spinal cord at each level.
  • Autonomic fibers have cell bodies in the horn too.
  • The anterior corticospinal tract transmits from the cerebral cortex over toward to the muscles around that central zone.
  • The lateral corticospinal tract is sourced from the cerebrum but even crosses inside that brainstem, so reaching LMNs with any spinal location.
  • Motor neurons of the spinal cord use acetylcholine (ACh) as neurotransmitter within the muscle junction.
  • When an action potential hits that nerve's end, Ca+ reaches that release neurotransmitters at opening and opening of synapse.

Spinal Reflexes

  • The reflex arc is a basic neuronal circuit where the sensory stimulus initiates a motor response instantly.
  • The sensory signals come from Ia nerve afferents from the spinal cord, that synapse with a-motor parts in those same muscles.
  • Ia interneurons inhibit a-motor neurons towards antagonist parts to the body.
  • Withdrawing one particular point by the sensory stimulus, typically something causing painful stimulus.
  • Activation upon entering it prevents homonymous to all parts associated muscle activity as primary stimulus or pain generator starts sending high input signals on spinal connections.

Dorsal Column-Medial Lemniscus System (DC-ML)

  • It relays awareness regarding fine touch sensitivity, vibratory perceptions, sense about where your parts happen at within space along touch, discrimination pressure etc, while DC–ML pathway then makes contact down with the medulla.
  • Ascending in ipsilateral posterior columns along the top location around what there happens here for its relay spot,
  • The information stemming for where that part is within relation when compared up higher gets routed down one direction, medially via its path along up inside those brain components.

Anterolateral System (Spinothalamic Tract)

The anterolateral component relays sensing touch, vibration, position and proprioception, though touch information about temp and pain starts one spinal area but eventually finds transmission to higher level destinations located up inside cortex

Descending and Rubrospinal Tract Characteristics

  • descending tracks regulate function originating at Brodmann's location 4 on the sides with the main pathway
  • Anterolateral column transmits motor knowledge on parts, therefore improving contralateral area's postural.

Clinical Significance of the NMJ

  • NMJ function is affected from diseases along lines on what can manifest through gravis, but Guillain barre symptoms has a contribution aspect to where demyelination causes slow to block conduction between regions, so causing both sensory as along with motor impairment.
  • Myasthenia gravis: This is an autoimmune illness, and it affects the acetylcholine receptors.
  • Guillon Barre syndrome: In this autoimmune version associated in PNS, the schwann cells take a hit.

Types of nerve fiber arrangement

  • peripheral cables exhibit cables arranged within called fasciculi, so enveloped in what’s named as ‘connective cables’.
  • Perineurium: These give security covering all individual nerve part.
  • Epineurium forms what’s thought with each layer found outermost so enveloping all about the components with fibers contained inner areas

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