Chapter 14 Questions based on objectives Flashcards
What are the 4 major parts of the brain?
- Brain stem
- Cerebellum
- Diencephalon
- Cerebrum
What is the brain stem?
continuous with spinal cord and consists of medulla oblongata, pons, and midbrain.
Where is the cerebellum?
posterior to the brain stem
What is the Diencephalon, and what does it consist of?
Superior to the brain stem.
It consists of the thalamus, hypothalamus, and epithalamus.
What is the cerebrum?
the largest part of the brain. Supported by diencephalon and brain stem.
What surrounds and protects the brain?
The cranial cavity bones and the cranial meninges
The cranial meninges are continuous with the spinal meninges and consist of what 3 parts?
the outer dura mater
the middle arachnoid mater
the inner pia mater
How is the dura mater in the brain different than those of the spinal cord?
The cranial dura mater has two layers; the spinal dura mater has only one.
What are the two layers of the dura mater called?
periosteal layer (which is external) and the meningeal layer (which is internal)
Is the periosteal layer of the dura mater internal or external?
which is external
Is the meningeal layer of the dura mater internal or external?
Internal
What is the function of the dural venous sinuses (endothelial-lined venous channels)
drain venous blood from the brain and deliver it into the internal jugular veins
Blood vessels that enter brain tissue pass along the surface of the brain and do what?
They penetrate inward they are sheathed by a loose-fitting sleeve of pia mater
What are the three extensions of the dura mater that separate parts of the brain?
(1) The falx cerebri
(2) The falx cerebelli
(3) The tentorium cerebelli
How does the falx cerebri separate parts of the brain?
Separates the two hemispheres (sides) of the cerebrum.
The brain represents only ___% of the total body weight.
2%
How much oxygen and glucose are used in the brain even when at rest?
It Consumes about 20% of the oxygen and glucose used by the body, even when resting.
Blood flows to the brain mainly via the _________and vertebral_______
internal carotid
and
vertebral arteries
___________consists mainly of tight junctions that seal together the endothelial cells of brain blood capillaries and a thick basement membrane that surrounds the capillaries.
blood-brain barrier (BBB)
What is Cerebrospinal fluid (CSF)
It is a clear, colourless liquid composed primarily of water that protects the brain and spinal cord from chemical and physical injuries.
__________are cavities within the brain that are filled with cerebrospinal fluid.
Ventricles
What are the four CSF-filled cavities within the brain?
2 lateral ventricles
third ventricle
fourth ventricle
What Protects the brain from chemical and physical injuries and nourishes neurons and neuroglia
Cerebrospinal Fluid
What are the three functions of the Cerebrospinal Fluid?
- Mechanical protection
- Homeostatic function
- Circulation
What is the Mechanical protection of the Cerebrospinal Fluid?
CSF acts as shock absorber the protects delicate brain tissue
What is the Homeostatic function of the Cerebrospinal Fluid?
the pH of CSF affects ventilation and cerebral blood flow. CSF also transports
polypeptide hormones secreted by hypothalamic neurons that act in the brain
What is the Circulation function of the Cerebrospinal Fluid?
CSF acts as an exchange medium for nutrients and wastes between blood and adjacent nervous tissue
Where is the majority of CSF produced?
Choroid Plexuses
What are the Choroid Plexuses?
networks of blood capillaries in the walls of the ventricles
___________ cells joined by tight junctions cover the capillaries of the choroid plexuses
Ependymal cells
Selected substances (mostly water) from the __________ filtered from the capillaries are secreted by the ependymal cells to produce the cerebrospinal fluid.
Blood plasma
CSF made in choroid plexuses of each lateral ventricle flows in the third ventricle through two narrow openings called ____________ ________
Interventricular foramina
CSF flows to the fourth ventricle through the aqueduct of the ___________
midbrain (cerebral aqueduct)
CSF enters the subarachnoid space through 3 openings in the roof of the fourth ventricle: What are the three openings?
1 median aperture
2 lateral apertures
What do arachnoid villi have to do with CSF?
CSF gradually reabsorbed in the blood through arachnoid villi, finger-like extensions of arachnoid matter that project in dural venous sinuses.
CSF __________ and ____________ are the same, so pressure and volume are constant.
formation
&
absorption
What is the brain stem?
The brain stem is the part of the brain between the spinal cord and the diencephalon
What are the three parts of the brain stem?
Consists of 3 parts: medulla oblongata, pons, and midbrain.
Where is the medulla oblongata?
Inferior part of the brain stem
Where does the medulla oblongata begin and end?
It begins at the foramen magnum and extends to the inferior border of the pons.
What type of matter is the medulla?
White matter
What does the white matter in the medulla contain?
Contains all sensory (ascending) tracts and motor (descending) tracts that go from the spinal cord to the brain
What are pyramids?
Are white matter bulges or protrusions formed by the large corticospinal tracts from the cerebrum to the spinal cord, controlling the voluntary movement of the limbs and trunk
What is the decussation of pyramids in the medulla?
Just superior to the junction of the medulla with the spinal cord, 90% of the axons in the left pyramid cross to the right side, and 90% of the axons in the right pyramid cross to the left side.
_______________centre in the medulla is a collection of neuronal bodies (called nuclei) that regulates the rate and force of heartbeat and diameter of blood vessels.
Cardiovascular
___________ _______________ centre (another nucleus) adjusts the basic rhythm of breathing.
Medullary respiratory
Besides regulating heartbeat, blood vessel diameter, and the normal breathing rhythm, nuclei in the medulla also control reflexes for what 5 other reflexes?
vomiting, swallowing, sneezing, coughing, and hiccupping
Vestibulocochlear (VIII) nerves convey what type of impulses?
These nerves convey impulses related to hearing.
These nerves convey impulses related to balance and equilibrium.
Glossopharyngeal (IX) nerves relay what type of information?
relay sensory and motor impulses related to taste, swallowing, and salivation via the glossopharyngeal nerves.
What do the Vagus (X) nerves receive?
Nuclei in the medulla receive sensory impulses from and provide motor impulses to the pharynx, larynx, and many thoracic and abdominal viscera via the vagus nerves.
Accessory (XI) nerves are part of what nerve?
Vagus (X)
Accessory (XI) nerves (cranial portion) are the origin of nerve impulses that control?
swallowing via the vagus nerves (a cranial portion of the accessory nerves)
Hypoglossal (XII) nerves are the origin for nerve impulses where?
That controls tongue movement during speech and swallowing via the hypoglossal nerves.
The medulla also contains nuclei that are components of sensory pathways. For what three components?
Gustation (taste), audition (hearing), and equilibrium (balance).
Where is the Pons located?
Superior to the medulla and anterior to the cerebellum.
What is the function of the pons?
It connects the right and left sides of the cerebellum by bundles of axons
Within pons are nuclei called _____ ________ ______, which, along with the medullary respiratory centre, helps control breathing.
pontine respiratory group,
Where are the Trigeminal (V) nerves located in the brain?
Pons
Where in the brand is Vestibulocochlear (VIII) nerves located?
In the medulla
Where in the brain are Glossopharyngeal (IX) nerves located?
Medulla
Where are Glossopharyngeal (IX) nerves located in the brain?
Medulla
Where are Accessory (XI) nerves (cranial portion) located?
Medulla
Where in the brain are Hypoglossal (XII) nerves located?
Medulla
where are Abducens (VI) nerves located within the brain?
Pons
Where can you find the Facial (VII) nerve within the brain?
Pons
What part of the brain are Vestibulocochlear (VIII) nerves located?
Pons
What do the Trigeminal (V) nerves do?
receive sensory impulses for somatic sensations from the head and face and provide motor impulses that govern chewing via the trigeminal nerves.
What does the Abducens (VI) nerve control?
Motor impulses that control eyeball movement
What do the Facial (VII) nerves do?
receive sensory impulses for taste and provide motor impulses to regulate secretion of saliva and tears
Where does the Midbrain (mesencephalon) extend from?
extends from pons to diencephalon
The anterior part of the midbrain contains paired bundles of axons called ___________
cerebral peduncles
The axon’s cerebral peduncles conduct impulses from where to where?
They conduct nerve impulses from motor areas of the cerebral cortex to the spinal cord, medulla, and pons.
What is reticular formation?
white matter and gray matter have a netlike arrangement
The superior colliculi serve as a reflex center for?
serve as reflex centers for certain visual activities.
The inferior colliculi relay impulses from where to where?
relaying impulses from the receptors for hearing in the inner ear to the brain
What type of nuclei are also a reflex centers for the startle reflex?
Inferior colliculi
What are the substantia nigra?
Nuclei which are large and darkly pigmented in the midbrain
Axons from the cerebellum and cerebral cortex form synapses in the _____ __________ which help control muscular movements.
red nuclei
Where do you find the Oculomotor (III) nerves?
The midbrain
Where do you find Trochlear (IV) nerves?
Midbrain
____________ nerves provide motor impulses that control movements of the eyeball via the trochlear nerves.
Trochlear (IV) nerves
What type of nerve provides motor impulses that control movements of the eyeball?
Oculomotor (III) nerves
Where does the reticular formation extend from, and to where?
It extends from the superior part of the spinal cord, throughout the brainstem, and into the inferior part of the diencephalon.
The reticular activating system (RAS) helps maintain what two things?
Attention
Alertness
The ascending portion of the reticular formation is called the?
reticular activating system (RAS)
What is one of the most important functions of the reticular activating system (RAS)?
consciousness
Name the 5 brain vesicles
The telencephalon,
The diencephalon
The mesencephalon.
The metencephalon.
The myelencephalon
The telencephalon develops into what Ventricle and what part of the brain?
develops into the cerebrum and lateral ventricles.
The diencephalon develops into what Ventricle and what part of the brain?
forms the thalamus, hypothalamus, epithalamus, and third ventricle.
The mesencephalon develops into what part of the brain?
midbrain, gives rise to the midbrain and aqueduct of the midbrain.
The metencephalon develops into what Ventricle and what part of the brain?
becomes the pons, cerebellum, and upper part of the fourth ventricle.
The myelencephalon develops into what Ventricle and what part of the brain?
forms the medulla oblongata and lower part of the fourth ventricle.
What is within the Olive of the Medulla?
Inferior olivary nucleus
What does the Inferior olivary nucleus do?
receives input from the cerebral cortex, red nucleus of the midbrain, and spinal cord
What does damage to the reticular activating system do?
Coma
What does the descending portion of the RAS have connections to?
Cerebellum and Spinal cord
What does the descending portion of the RAS that is associated with the Cerebellum and Spinal cord help regulate?
Muscle tone
Where is the Cerebellum located?
The cerebellum is posterior to the medulla and pons and inferior to the posterior portion of the cerebrum
What two deep groves separate the cerebellum from the cerebrum?
transverse cerebral fissure, along with the tentorium cerebelli,
What are the two lobes that are separated in the cerebellum?
Cerebellar hemispheres or
Right and Left Hemispheres
The anterior lobe and posterior lobe of the cerebellum govern subconscious aspects of?
Skeletal muscle movement
Where is the flocculonodular lobe located?
Cerebellum
What is The flocculonodular lobe?
On the inferior surface or the cerebellum which contributes to equilibrium and balance.
The superficial layer of the cerebellum is called the?
the cerebellar cortex
What does the cerebellar cortex consist of?
consists of gray matter in a series of slender, parallel ridges
What is the name of the gray matter in the cerebellum that is in a series of slender, parallel ridges?
folia
What are folia?
gray matter within the cerebellum that are in a series of slender, parallel ridges
What is arbor vitae?
Deep to the gray matter are tracts of white matter (of the cerebellum)
What are cerebellar nuclei?
Regions of gray matter that give rise to axons carrying impulses from the cerebellum to other brain centers.
What are cerebellar peduncles?
They are what attach the cerebellum of the brainstem
How many pairs of cerebellar peduncles attach the cerebellum to the brainstem?
three
What are the names of the pairs of cerebellar peduncles that attach the cerebellum to the brainstem?
Superior
Middle
Inferior
Where do the Superior Cerebellar Peduncles conduct impulses to?
Contain axons that extend from the cerebellum to the midbrain’s red nuclei and several thalamus nuclei.
Where do the Middle Cerebellar Peduncles conduct impulses too?
Carry impulses for voluntary movements from the pontine nuclei (which receive input from motor areas of the cerebral cortex) into the cerebellum
What is The primary function of the cerebellum?
skilled movements,
&
regulates posture and balance.
The cerebral cortex suggests that the cerebellum may also have nonmotor functions such as?
cognition
language processing
learning and responding to anticipated rewards
What are the 3 parts of the diencephalon?
the thalamus, hypothalamus, and epithalamus
Projecting from the hypothalamus is what gland?
pituitary gland
What are the primary functions of the thalamus? There are 4
- Relay station for most sensory impulses
- Transmitting information to the primary motor cortex of the cerebrum
- Relays nerve impulses between different areas of the cerebrum
- Plays a role in the maintenance of consciousness
A bridge of gray matter called the _________ _________ joins the right and left halves of the thalamus
interthalamic adhesion
A vertical Y-shaped sheet of white matter called the _______ _________ ________ divides the gray matter of the right and left sides of the thalamus
internal medullary lamina
Axons that connect the thalamus and cerebral cortex pass through the ______ ______, a thick band of white matter lateral to the thalamus
internal capsule
Optic (II) Components and Principle Functions
Components: Special sensory
Principle Function: Vision (sight).
Oculomotor (III) Components and Principle Functions
Components: Motor
Somatic
Motor (autonomic)
Principle Function:
Movement of eyeballs and upper eyelid. Adjusts lens for near vision (accommodation). Constriction of pupil.
Trochlear (IV) Components and Principle Functions
Components: Motor /Somatic
Principle Function: Movement of eyeballs.
Trigeminal (V) Components and Principle Functions
Components: Mixed
Sensory
Motor (branchial)
Principle Function:
Touch, pain, and thermal sensations from scalp, face, and oral cavity (including teeth and anterior two-thirds of tongue).
Chewing and controls middle ear muscle.
Abducens (VI) Components and Principle Functions
Components: Motor
Somatic
Principle Function: Movement of eyeballs.
Facial (VII) Components and Principle Functions
Components: Mixed
Sensory
Motor (branchial) Motor (autonomic)
Principle Function:
Taste from anterior two-thirds of tongue.
Touch, pain, and thermal sensations from skin in external acoustic meatus. Control of muscles of facial expression and middle ear muscle.
Secretion of tears and saliva.
Vestibulocochlear (VIII) Components and Principle Functions
Components: Special sensory
Principle Function: Hearing and equilibrium.
Glossopharyngeal (IX) Components and Principle Functions
Components: Mixed
Sensory
Motor (branchial) Motor (autonomic)
Principle Function:
Taste from posterior one-third of tongue.
Proprioception in some swallowing muscles.
Monitors blood pressure and oxygen and carbon dioxide levels in blood.
Touch, pain, and thermal sensations from skin of external ear and upper pharynx. Assists in swallowing.
Secretion of saliva.
Vagus (X) Components and Principle Functions
Components: Mixed
Sensory
Motor (branchial) Motor (autonomic)
Principle Function:
Taste from epiglottis.
Proprioception from throat and voice box muscles.
Monitors blood pressure and oxygen and carbon dioxide levels in blood. Touch, pain, and thermal sensations from skin of external ear. Sensations from thoracic and abdominal organs.
Swallowing, vocalization, and coughing.
Motility and secretion of digestive canal organs.
Constriction of respiratory passageways.
Decreases heart rate.
Accessory (XI) Components and Principle Functions
Components: Motor Branchial
Principle Function:
Movement of head and pectoral girdle.
Hypoglossal (XII) Components and Principle Functions
Components: Motor
Somatic
Principle Function:
Speech, manipulation of food, and swallowing.
Olfactory (I) Components and Principle Functions
Components: Special sensory
Principle Function: Olfaction (smell).
Olfactory nerve (I) Originate and Foremen?
They originate in the receptors of the olfactory epithelium and pass through the olfactory foramina in the cribriform plate of the ethmoid bone, ending at the olfactory bulbs.
Optic (II) Nerve Originate and Foremen?
This nerve passes through the optic foramen and enters the skull.
Oculomotor (III) Originate and Foremen?
The oculomotor nerve extends anteriorly and divides into superior and inferior branches, both of which pass through the superior orbital fissure into the orbit
Trochlear (IV) Originate and Foremen?
The axons originate in the trochlear nucleus in the midbrain and then exit posteriorly.
Abducens (VI) Originate and Foremen?
The nerve passes into the orbit through the superior orbital fissure.
Trigeminal (V) Originate and Foremen?
It emerges from two roots on the ventrolateral surface of the pons
Facial (VII) Originate and Foremen?
Axons of branchial motor neurons arise from a nucleus in the pons, pass through the petrous portion of the temporal bone, and innervate facial, scalp, and neck muscles
Vestibulocochlear (VIII) Originate and Foremen?
the vestibular branch extend from the semicircular canals, the saccule, and the utricle of the inner ear to the vestibular ganglion where their cell bodies are located, and end in vestibular nuclei in the pons
Glossopharyngeal (IX) Originate and Foremen?
glossopharyngeal nerve arise in nuclei of the medulla and exit the skull through the jugular foramen.
Vagus (X) Originate and Foremen?
These axons form nerves that join the main vagus trunk and enter the skull through the jugular foramen. They end in the medulla oblongata and pons in various nuclei.
Accessory (XI) Originate and Foremen?
Its motor axons arise in the anterior gray horn of the first five segments of the cervical portion of the spinal cord. The axons exit these spinal cord segments laterally and unite to ascend along the spinal cord and enter the skull through the foramen magnum
Hypoglossal (XII) Originate and Foremen?
The somatic motor axons originate in the hypoglossal nucleus in the medulla oblongata, pass through the hypoglossal canal, and supply the muscles of the tongue.
