Term 3 Chapter 18 Brain Flashcards
What is the brain in terms of nervous system?
The brain is the portion of the CNS that is contained within the cranium (cranial cavity)
What are the four major regions of the brain?
- Brainstem
- Cerebellum
- Diencephalon
- Cerebrum
What are three parts of the Brainstem?
- Midbrain
- Pons
- Medulla oblongata
What are three parts of the Diencephalon?
- Epithalamus (includes pineal gland)
- Thalamus
- Hypothalamus
The cerebrum is split into a right and left _______, each half has ____ lobes?
hemisphere, Five
What four structures play a role in support and protection of the brain?
- Cranium (skull)
- Cranial Meninges
- Cerebrospinal Fluid (CSF)
- Blood-Brain barrier
How does cerebrospinal fluid protect and support the brain?
CSF is clear, colourless fluid that protects the brain and spinal cord against chemical and physical injury
The cranial meninges are _______ with the spinal meninges: Outer ________, Middle________, and Innermost _________
The cranial meninges are continuous with the spinal meninges: Outer dura mater, Middle arachnoid mater, and Innermost pia mater
How does the cranial dura mater compare to the spinal dura mater?
The cranial dura mater has 2 layers while the spinal dura mater has only one
Between the spinal dura mater and the vertebral wall, there is an epidural space. Where is the epidural space around the brain?
There is NO epidural space around the brain
The two cranial dura mater layers around the brain are fused together and separate to enclose the __________
The two cranial dura mater layers around the brain are fused together and separate to enclose the dural venous sinuses
What are the dural venous sinuses?
Endothelial lined venous channels that drain venous blood from the brain and deliver it into the internal jugular veins
The dura mater form 3 extensions that separate parts of the brain. What are these extensions and what do they separate?
- Falx cerebri: separates the two hemispheres of the cerebrum
- Falx cerebelli: separates the two hemispheres of the cerebellum
- Tentorium cerebelli: separates the cerebrum from the cerebellum
What are the three main functions of the cerebrospinal fluid (CSF)?
- Mechanical protection: absorbs shock
- Chemical protection: CSF provides optimal chemical environment for neuronal signalling
- Circulation: medium for minor exchange in nutrients and oxygen and waste products between blood and nervous tissue
Where does the majority of CSF production occur?
In the choroid plexuses (capillary networks) in the walls of ventricles
How many CSF-filled ventricles can be found in the brain? What is their purpose?
4
Serve as a reservoir of CSF secreted from adjacent choroid plexuses
What are the four csf-filled ventricles in the brain called?
- 2x lateral ventricles (one in each hemisphere of the cerebrum)
- Third ventricle
- Fourth ventricle
The two lateral ventricles are separated by the_______
the septum pelucidum
Which ventricle lies between the brainstem and cerebellum
the fourth ventricle
Which ventricle is a narrow cavity along midline superior to the hypothalamus, and between the right and left halves of the thalamus
The third ventricle
CSF Circulation:
- CSF formed in the choroid plexuses of each lateral ventricle flows into the third ventricle through the ___________\_
- More CSF added in the ________
- CSF then flows to the _______ via the ______ of the midbrain (______) - passes through the midbrain
- Small amounts of CSF travel downward through the _______ of the spinal cord
- Majority of CSF enters the ________ via the 3 openings (______, or paired ______) in the _________
- CSF formed in the choroid plexuses of each lateral ventricle flows into the third ventricle through the Interventricular foramina
- More CSF added in the third ventricle
- CSF then flows to the fourth ventricle via the aqueduct of the midbrain ( cerebral aqueduct) - passes through the midbrain
- Small amounts of CSF travel downward through the central canal of the spinal cord
- Majority of CSF enters the subarachnoid space via the 3 openings ( Median aperture , or paired lateral apertures ) in the fourth ventricle
CSF circulation continued:
- CSF then circulates through the ________ around the surface of the brain and spinal cord
- CSF is gradually reabsorbed into the blood through _________
- CSF then circulates through the Subarachnoid space around the surface of the brain and spinal cord
- CSF is gradually reabsorbed into the blood through arachnoid villi
What are arachnoid villi?
Fingerlike extensions of the arachnoid that project into the dural venous sinuses, especially the superior sagittal sinus
Label the summary of the formation, circulation and absorption of CSF
Label the sagittal section of the brain
What is the function blood-brain barrier?
Protects brain from harmful substances and pathogens
- very selective of what can cross
- Proteins and antibiotics cannot cross
- small compounds (ie oxygen, carbon dioxide, anaesthetic drugs and alcohol) can cross
What does the blood brain barrier consist of?
What is the purpose of astrocytes in the BBB?
Tight junctions between endothelial cells of brain capillaries
- Thick basement membrane surrounds the capillaries
- Astrocytes help maintain the strength of tight junctions
The Brainstem is part of the brain between the _____ and the ______ and consists of three structures:
The Brainstem is part of the brain between the spinal cord and the diencephalon and consists of three structures:
- Midbrain
- Pons
- Medulla oblongata
What is the Reticular formation?
net-like region of interspersed grey and white matter that extends throughout the brainstem
The ________ is a continuation of the superior part of the spinal cord\
Medulla oblongata
The medulla oblongata begins at the _______ and extends to the inferior border of the _____ to form the ______ part of the brainstem
The medulla oblongata begins at the foramen magnum and extends to the inferior border of the pons to form the inferior part of the brainstem
The medulla oblongata contains nuclei that control vital functions; what are these nuclei?
Masses of grey matter where neurons synapse with other neurons
The medulla oblongata has four “centers” that control various functions. What are they?
- Cardiac centre: controls rate of heartbeat
- Vasomotor centre: controls blood pressure by causing arteriole constriction
- Respiratory centre: controls the rate and depth of breathing
- Centres of reflex: eg sneezing, coughing, swallowing etc
What are pyramids in the medulla oblongata?
White matter that bulges on the anterior aspects of the medulla
What is decussation of the pyramidal olive?
crossing of axons of the spinal cord from right to left and vice versa
What does the inferior olivary nucleus (in medulla oblongata) do
Relay impulses from proprioceptors to cerebellum
What are the gracile and cutaneous nuclei (medulla oblongata)
How do signals travel here?
Associated with touch, pressure, vibrations and proprioception
Signal travels in axons through the medial lemniscus to the thalamus
What five pairs of cranial nerves have nuclei of origin in the medulla oblongata?
- Vestibulocochlear (VIII) nerves - hearing
- Glossopharyngeal (IX) nerves - taste, swallowing and salivation
- Vagus (X) nerves - mixed (sensory and motor) nerve that is widely distributed from the head, neck into the thorax and abdomen
- Accessory (XI) nerves - cranial portion include the first five segments of the cervical spinal cord to coordinate head movements
- Hypoglossal (XII) nerves - control the tongue relating to speech and swallowing
The pons consists of ______(____) and _____ and forms a _____ that connects parts of the brian with one another
The pons consists of nuclei (pontine nuclei) and tracts and forms a bridge that connects parts of the brain with one another; connect the right and left sides of the cerebellum
the pons links the cerebellum with the ______, _______, _____, ______, and ______
the pons links the cerebellum with the midbrain, diencephalon, cerebrum, medulla oblongata, and spinal cord
Label:
The pons contains nuclei associated with which four pairs of cranial nerves? What are each of these nerves in charge of?
- Trigeminal (V) nerves - receive sensory impulses from the head and face and provide motor impulses that control chewing
- Abducens (VI) nerves - motor control of eyeball movements
- Facial (VII) nerves - receive sensory impulses for taste, provide motor impulses that control salivation, tears, and facial expressions
- Vestibulocochlear (VIII) nerves - nerves of the vestibular apparatus of the inner ear relating to balance and equilibrium
The midbrain (aka mesencephalon) extends from the ____ to the _____
The midbrain extends from the pons to the diencephalon
The ______ passes through the midbrain connecting the ____ ventricle above to the _____ ventricle below
The Cerebral aqueduct passes through the midbrain connecting the third ventricle above to the fourth ventricle below
The anterior part of the midbrain contains a pair of tracts called________
Cerebral peduncles
The posterior part of the midbrain is called the _______, and has two features:
tectum
- Superior colliculi
- Inferior colliculi
What are the superior colliculi (midbrain)
two superior elevations of the midbrain
- nuclei that serves as the centers for certain visual activities eg tracking eye movements/ movements of head and neck