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Questions and Answers
Which lobe of the cerebrum is primarily responsible for processing visual information?
Which lobe of the cerebrum is primarily responsible for processing visual information?
What is the primary function of the basal nuclei?
What is the primary function of the basal nuclei?
Which structure connects both cerebral hemispheres?
Which structure connects both cerebral hemispheres?
What is the structure that forms a protective covering for the spinal cord and extends to the vertebral level S2?
What is the structure that forms a protective covering for the spinal cord and extends to the vertebral level S2?
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What type of fibers connect different regions within the same cerebral hemisphere?
What type of fibers connect different regions within the same cerebral hemisphere?
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Which spinal nerves are categorized as contributing to the cauda equina?
Which spinal nerves are categorized as contributing to the cauda equina?
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The primary somatosensory cortex is responsible for interpreting what type of information?
The primary somatosensory cortex is responsible for interpreting what type of information?
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Damage to which area leads to expressive aphasia?
Damage to which area leads to expressive aphasia?
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Which of the following components surrounds each individual nerve fiber?
Which of the following components surrounds each individual nerve fiber?
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Which part of the brainstem serves as a relay between the spinal cord and the cerebrum?
Which part of the brainstem serves as a relay between the spinal cord and the cerebrum?
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What type of nerve carries both sensory and motor fibers?
What type of nerve carries both sensory and motor fibers?
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What term describes the area of skin that is innervated by a specific spinal level?
What term describes the area of skin that is innervated by a specific spinal level?
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What is the main function of the cerebellum?
What is the main function of the cerebellum?
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Which component of the nervous system is primarily involved in the 'fight or flight' response?
Which component of the nervous system is primarily involved in the 'fight or flight' response?
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What are the ventral rami of spinal nerves primarily responsible for?
What are the ventral rami of spinal nerves primarily responsible for?
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Which structure marks the terminus of the spinal cord?
Which structure marks the terminus of the spinal cord?
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What defines the structure of the spinal nerves?
What defines the structure of the spinal nerves?
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What is the primary function of the autonomic nervous system?
What is the primary function of the autonomic nervous system?
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Which structure of the CNS is associated with auditory processing?
Which structure of the CNS is associated with auditory processing?
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What is the role of the thalamus in the central nervous system?
What is the role of the thalamus in the central nervous system?
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How many pairs of spinal nerves emerge from the spinal cord segments?
How many pairs of spinal nerves emerge from the spinal cord segments?
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Which type of white matter tract carries information from the cortex to lower CNS parts?
Which type of white matter tract carries information from the cortex to lower CNS parts?
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Which of the following is NOT typically considered a component of the peripheral nervous system?
Which of the following is NOT typically considered a component of the peripheral nervous system?
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Which membrane is the outermost protective layer surrounding the brain?
Which membrane is the outermost protective layer surrounding the brain?
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What component forms the bundle of nerve fibers within a nerve?
What component forms the bundle of nerve fibers within a nerve?
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What is the primary role of the spinal cord in relation to the brain?
What is the primary role of the spinal cord in relation to the brain?
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Which cranial nerve mnemonic helps remember the sequence of cranial nerves?
Which cranial nerve mnemonic helps remember the sequence of cranial nerves?
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Which neurotransmitter is primarily associated with the postganglionic neurons of the sympathetic division?
Which neurotransmitter is primarily associated with the postganglionic neurons of the sympathetic division?
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What area of the spinal cord do preganglionic neurons of the sympathetic division originate from?
What area of the spinal cord do preganglionic neurons of the sympathetic division originate from?
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The parasympathetic division is also referred to as which of the following?
The parasympathetic division is also referred to as which of the following?
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Which of the following accurately describes the primary function of the parasympathetic division?
Which of the following accurately describes the primary function of the parasympathetic division?
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Where do the postganglionic neurons of the parasympathetic division typically reside?
Where do the postganglionic neurons of the parasympathetic division typically reside?
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How do the sympathetic and parasympathetic divisions generally work together?
How do the sympathetic and parasympathetic divisions generally work together?
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Which cranial nerves contain the preganglionic neurons of the parasympathetic division?
Which cranial nerves contain the preganglionic neurons of the parasympathetic division?
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What is the primary pathway for postganglionic neurons in the sympathetic division?
What is the primary pathway for postganglionic neurons in the sympathetic division?
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What physiological response is primarily triggered by the sympathetic division?
What physiological response is primarily triggered by the sympathetic division?
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Which segment of the spinal cord do preganglionic neurons of the parasympathetic division originate from?
Which segment of the spinal cord do preganglionic neurons of the parasympathetic division originate from?
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Study Notes
Nervous System Objectives
- Identify and name the brain lobes, major sulci, and gyri
- Describe the concept of functional localization of the brain
- Explain the function of basal nuclei and diencephalon
- Differentiate between types of cerebral white matter
- Identify the parts and describe functions of the brain stem
- State functions of the cerebellum
- Describe the internal and external structure of spinal cords
- Understand the structure of spinal nerves
- Describe major nerve plexuses and their main branches
- Differentiate between sympathetic and parasympathetic divisions of the nervous system
General Organization of the CNS
- The CNS is comprised of the cerebrum, diencephalon, cerebellum, and brainstem
- The cerebrum is the largest part of the brain, controlling higher mental functions
- The cerebrum is divided into hemispheres by the longitudinal fissure
- Each hemisphere consists of grey matter (cell bodies of neurons) forming the cerebral cortex and buried deeply to form diencephalon and basal nuclei
- White matter comprises axons of neurons forming tracts
- The diencephalon is located under the cerebrum and consists of the thalamus, hypothalamus, and epithalamus
- The cerebellum is the second largest part of the brain, composed of two hemispheres covered with cerebellar cortex and inner white matter
- The cerebellum coordinates repetitive smooth body movements and is responsible for body balance and posture
- The brainstem includes the midbrain, pons, and medulla oblongata, which processes information between the spinal cord and cerebrum/cerebellum
Cerebral Cortex
- The folded surface of the cerebral cortex increases surface area
- The elevated folds are called gyri
- The shallow depressions are called sulci
- Deep grooves are called fissures
Grooves and Lobes of the Cerebrum
- The frontal lobe lies in front of the central sulcus
- The parietal lobe lies behind the central sulcus
- The temporal lobe lies below the lateral fissure
- The occipital lobe lies at the back of the brain
Functional Areas of the Cerebrum
- The primary motor cortex is responsible for voluntary movement
- The premotor area is associated with working memory and judgment
- The posterior association area is for speech and language comprehension
- The visual area is for vision
- The auditory area is for hearing
- Broca's area is for motor speech
- The olfactory area is for smell
- The primary somatosensory area is for interpretation of somatosensation (touch)
Deep Grey Matter: Basal Nuclei
- Assist in the regulation of voluntary motor activities
- Modifies instructions sent to skeletal muscles
- Lesions can result in Parkinson's disease
Deep Grey Matter: Diencephalon
- Located under the cerebrum
- Links cerebrum with the brain stem
- Includes thalamus, hypothalamus, and epithalamus
Cerebral White Matter
- Commissural fibers connect areas within the same hemisphere via tracts such as corpus callosum
- Projection fiber tracts connect the cerebrum to lower CNS centers
- Association fibers connect areas within the same hemisphere
Brainstem
- Include the midbrain, pons, and medulla oblongata
- Provide a pathway for ascending and descending tracts
- Contains gray matter nuclei associated with cranial nerves and autonomic centers
- Contains diffuse gray matter (reticular formation) vital for consciousness
Cerebellum
- The second largest part of the brain
- Composed of two hemispheres covered with cerebellar cortex and inner white matter
- Coordinates repetitive smooth body movements
- Responsible for body balance and posture
Protections of the Brain
- Bone: Skull
- Membranes: Dura, arachnoid, and pia mater
- Fluid: Cerebrospinal fluid
Blood Supply to the Brain
- Internal carotid system supplies the cerebrum and diencephalon
- Vertebrobasilar system supplies brainstem, cerebellum, and spinal cord
- Anastomosis between the two systems ensures adequate blood supply
Spinal Cord: Overview
- Spinal cord is shorter than the vertebral column
- CSF in the expanded subarachnoid space between L2 and S2 is called the lumbar cistern
- Dura and arachnoid form the dural sac extending to vertebral level S2
External Features of the Spinal Cord
- Spinal cord ends as conus medullaris at vertebral level L2
- More caudal nerves descend to exit between appropriate vertebrae to form the cauda equina
- Pial extension from conus medullaris forms the filum terminale interna
Spinal Nerves
- 31 pairs of spinal nerves emerge from 31 spinal cord segments (Cervical - 8, Thoracic - 12, Lumbar - 5, Sacral - 5, Coccygeal - 1)
Internal Features of the Spinal Cord
- White matter surrounds the central canal
- Gray matter consists of dorsal horns, lateral horns, and ventral horns
CNS Major Tracts in the CNS
- Sensory information to cerebral cortex
- Integration (processing) and interpretation of sensory input
- Interneuron response to motor neurons for response
Structure of a Nerve
- A nerve is a bundle of neuron fibers
- Each fiber is surrounded by endoneurium
- A bundle of fibers is known as a fascicle surrounded by perineurium
- Fascicles are bound together by epineurium
Cranial Nerves
- Olfactory (I), Optic (II), Oculomotor (III), Trochlear (IV), Trigeminal (V), Abducens (VI), Facial (VII) Auditory (VIII), Glossopharyngeal (IX), Vagus (X), Accessory (XI), Hypoglossal (XII)
Distribution of Cranial Nerves
- Sensory, motor functions, and tests for the specific nerves
Dermatomes and Myotomes
- Dermatome: area of skin innervated by a given spinal level
- Myotome: group of muscles supplied by a given spinal level
- Spinal nerve lesions lead to loss of sensory and motor functions
Nerve Plexuses
- Dorsal and ventral rami are mixed nerves
- Ventral rami blend to create compound nerves
- Each nerve carries axons from 2 or more spinal segments
- The network of ventral rami is called a nerve plexus
Formation of Nerve Plexuses
- Cervical Plexus (C1-C4)
- Brachial Plexus (C5-T1)
- Lumbar Plexus (L1-L4)
- Sacral Plexus (L4-S4)
Major Nerves of the Upper Limb
- Axillary nerve
- Radial nerve
- Musculocutaneous nerve
- Ulnar nerve
- Median nerve
Major Nerves of the Lower Limb
- Femoral nerve
- Lateral femoral cutaneous nerve
- Obturator nerve
- Anterior femoral cutaneous nerve
- Saphenous nerve
- Sciatic nerve
- Posterior femoral cutaneous nerve
- Common fibular nerve (superficial and deep branches)
- Tibial nerve
- Sural nerve
Overview of the Autonomic Nervous System
- Functions independently without conscious effort
- Regulates the activity of involuntary muscles, cardiac muscles, and glands
- Responds to emotional stress and prepares the body for strenuous physical activity
- Part of the peripheral nervous system
Divisions of Peripheral Nervous System
- Central Nervous System (processes information, stores info, sends orders)
- Peripheral Nervous System (transmits to and from CNS)
- Somatic (controls skeletal muscles)
- Autonomic (regulates glands, blood vessels, internal organs)
- Sympathetic (mobilizes body for action)
- Parasympathetic (conserves energy)
Somatic Nervous System vs. Autonomic Nervous System
- ANS has two neurons between CNS and effector organs
- Preganglionic neuron
- Postganglionic neuron
Overview of Preganglionic and Postganglionic Neurons
- Preganglionic neurons arise from cell bodies in the brain and spinal cord
- Postganglionic neurons emerge from cell bodies in ganglia
Divisions of Autonomic Nervous System
- Neurotransmitters released by postganglionic neurons:
- Sympathetic: Epinephrine (adrenaline), norepinephrine
- Parasympathetic: Acetylcholine
Structure of the Autonomic Nervous System
- Both serve the same organs
- Cause opposite effects
- Activities are counterbalanced
Parasympathetic vs Sympathetic Nervous System
- Parasympathetic division brings up relaxed state, allows conservation of energy
- Sympathetic division coordinates the body for the "fight or flight" response
Anatomy of Parasympathetic Division I & II
- Preganglionic neurons located in:
- Brain nuclei of cranial nerves III, VII, IX, and X
- Spinal cord segments S2 to S4 (also known as craniosacral division)
- Preganglionic neurons in cranial region travel with cranial nerve fibers, serve head and neck
- Preganglionic neurons in sacral region leave the spinal cord and form pelvic splanchnic nerves
- Postganglionic neurons located in the wall of viscera
Function of Parasympathetic Division
- Decreases heart rate
- Decreases contractility
- Stimulates digestion
- Constrict pupils
- Stimulates salivation
- Bronchial constriction
- Stimulate gallbladder
- Contracts bladder
- Relaxes rectum
- Vaginal lubrication
- Erection
Anatomy of Sympathetic Division
- Preganglionic neurons located in the gray matter of spinal cord segments T1 to L2
- Sympathetic division also known as thoracolumbar division
- Preganglionic neurons exit the spinal cord and enter sympathetic trunk ganglia
- Postganglionic neurons reenter the spinal nerve
Preganglionic Neuron of Sympathetic Division
- Preganglionic neurons located in the spinal cord gray matter
- Exit through ventral root of spinal nerve
- Travel through spinal nerve
- Enter sympathetic trunk ganglia
Postganglionic Neuron of Sympathetic Division
- Postganglionic neurons renter spinal nerve, exit through ventral ramus to effector
Sympathetic Pathways
- Sympathetic trunk ganglion
- Splanchnic nerve
- Collateral ganglion (e.g. celiac)
Function of Sympathetic Division
- Dilates pupils
- Inhibits salivation
- Increases heart rate
- Increases contractility
- Bronchial dilation
- Inhibits digestion
- Stimulates glucose release
- Stimulates epinephrine and norepinephrine release
- Relaxes bladder
- Contracts rectum
- Orgasm
- Ejaculation
- Peripheral vasoconstriction
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