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Questions and Answers
What is a primary function of the reticular formation in the brain?
Which area of the midbrain is responsible for the reflection towards auditory stimuli?
What role does the thalamus play in the central nervous system?
Which hypothalamic function is essential for maintaining homeostasis?
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What is the primary role of the medulla oblongata?
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Which nuclei are involved in processing visual information in the thalamus?
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What is one of the primary functions of the cerebellum?
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Which structure serves as a bridge connecting the forebrain to the cerebellum?
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Which structure in the brainstem is primarily responsible for autonomic functions such as breathing and heart rate?
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Which part of the spinal cord is responsible for transmitting afferent signals?
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What is the primary function of the cerebellum?
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What type of information does the ventral posterior nuclei of the thalamus relay?
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Which structure contains the cell bodies of many cranial nerves?
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Where do corticospinal motor axons cross to control muscles from the opposite side of the body?
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Which of the following functions is NOT typically associated with the pons?
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What type of neuron is primarily associated with spinal reflexes, such as the knee jerk reflex?
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What is the role of myelin sheets in the central nervous system (CNS)?
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Which layer of the meninges is the thickest and closest to the skull?
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What is the primary function of cerebrospinal fluid (CSF) within the CNS?
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Which of the following arteries is NOT a main source of blood supply to the brain?
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What is the primary function of the medulla in the brainstem?
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Which of the following is a function of the cerebellum?
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The circle of Willis is important because it:
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Which part of the CNS includes the thalamus and hypothalamus?
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Study Notes
The Nervous System – CNS
- The CNS is protected by the meninges, a series of three protective membranes:
- Dura Mater: Thick membrane, closest to the skull.
- Arachnoid Mater: Not attached to the dura mater. Does not line the brain down to the sulci (except for the longitudinal fissure).
- Pia Mater: Delicate membrane that firmly adheres to the surface of the brain. It can be infected (i.e., meningitis).
- The brain floats in cerebrospinal fluid (CSF) which fills the subarachnoid space between the arachnoid membrane and the pia mater.
- CSF protects the brain by reducing shock and cleanses it.
- Cavities in the brain are filled with CSF called ventricles.
- Four large connected ventricles:
- Left and right lateral ventricle
- Third ventricle
- Fourth ventricle
- Four large connected ventricles:
- The brain needs energy and oxygen which is delivered via blood.
- The brain consumes about 20% of your blood supply.
- Interruptions of blood supply to the brain (i.e., a stroke) can be caused by an obstruction of an artery or by hemorrhage from a blood vessel. This can cause damage to the brain (i.e., brain lesions).
- Brain blood supply originates from two main sources:
- Internal carotid arteries
- Vertebral arteries
- The left and right vertebral arteries merge at the level of the pons to form the basilar artery.
- The basilar artery and the internal carotid arteries meet at the circle of Willis.
Structure of the CNS
- The CNS is composed of four basic parts:
- Spinal cord
- Brainstem
- Diencephalon
- Telencephalon (Cerebrum)
- Cerebral Cortex
- Basal Ganglia
- Limbic System
Spinal Cord
- Enclosed by the bony vertebral column, which is divided into cervical, thoracic, lumbar, sacral, and coccygeal regions.
- Each segment of the vertebral column gives rise to peripheral (spinal) nerves that innervate the body.
- Sensory signals enter the spinal cord via the dorsal horn (afferent signals, towards the CNS), while motor signals leave via the ventral horn (efferent signals, away from the CNS).
- Some signals travel directly from the dorsal to the ventral horn via an interneuron (e.g., spinal reflexes like the knee jerk).
Brainstem
- A highly complex structure, essential for the maintenance of life. Damage to the brainstem is severe.
- Composed of three main parts:
- Medulla (oblongata)
- Pons + Cerebellum
- Midbrain
Medulla (oblongata)
- Contains cell bodies of many of the 12 cranial nerves (sensory and motor innervations to face, neck, throat).
- Corticospinal motor axons (axons coming from the cortex to the spinal cord) cross here. Motor neurons from the left hemisphere cross to control muscles on the right side of the body.
- Responsible for autonomic (involuntary) functions like heart rate, sneezing, blood pressure, etc.
Pons + Cerebellum
- Pons (‘bridge'): Contains nuclei connecting the forebrain to the cerebellum, and nuclei dealing with sleep, swallowing, facial expressions, and more. Also involved in sleep paralysis.
- Cerebellum (‘little brain'):
- Houses approximately 70 billion neurons!
- Known for motor control and maintaining balance.
- Also implicated in cognitive processing (e.g., language, attention).
- Reticular formation: Located throughout the brainstem, crucial for arousal and attention.
Midbrain (Mesencephalon)
- Dorsal part (tectum): Houses superior and inferior colliculi involved in reflex responses to visual and auditory stimuli, respectively.
- Ventral part (tegmentum): Houses the Ventral Tegmental Area and Substantia Nigra, where dopamine is produced.
- Periaqueductal Grey: Modulates pain signals.
Diencephalon
- Composed of the thalamus and hypothalamus.
Thalamus
- Left and right thalamus, connected via the Massa Intermedia.
- Switchboard of the brain. Receives input from all sensory areas of the brain (except smell).
- Composed of several nuclei acting as specific relays for incoming sensory information:
- Lateral geniculate nucleus: Visual information
- Medial geniculate nucleus: Auditory information
- Ventral posterior nuclei: Somatosensory information
- Pulvinar: Attention and integrative functions.
Hypothalamus
- Controls functions necessary for homeostasis (normal state of the body):
- Body temperature
- Metabolic rate
- Circadian rhythm
- Produces hormones and regulates hormone production in other areas (e.g., pituitary gland).
- Axonal connections to the posterior pituitary gland.
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Description
Explore the complexities of the Central Nervous System (CNS) in this quiz. Learn about the protective layers of the brain, the cerebrospinal fluid, and the ventricles that play critical roles in brain function. Test your knowledge of how the brain is nourished and protected.
