Anatomy of the Brain Flashcards
(108 cards)
1
Q
What is the embryological origin of the nervous system?
A
Ectoderm
2
Q
The process of development of the nervous system is called what?
A
Neurulation from notochord to neural tube
3
Q
The ectodermal thickening that transforms into the brain is called what?
A
Neural plate
4
Q
Describe the transition from the neural plate to the 3 brain vesicles.
A
Neural plate -> neural groove -> neural tube -> 3 brain vesicles
5
Q
What are the names of the 3 brain vesicles?
A
- Prosencephalon (forebrain)
- Mesencephalon (midbrain)
- Rhombencephalon (hindbrain)
6
Q
The rostral end and the caudal end of the neural tube forms what structures?
A
Rostral end: brain
Caudal end: spinal cord
7
Q
What are the parts of the prosencephalon?
A
Telencephalon: cerebral hemispheres
Diencephalon: thalamus and hypothalamus
8
Q
The entirety of the mesencephalon forms what structure?
A
Midbrain
9
Q
What are the parts of the rhombencephalon?
A
Metencephalon: pons and cerebellum
Myelencephalon: medulla oblongata
10
Q
What are the subdivisions of the brain?
A
- Cerebrum: left and right hemispheres
- Cerebellum
- Brain stem: midbrain, pons, medulla
11
Q
What structure connects the cerebrum with the spinal cord?
A
Brain stem
12
Q
What are the names of the numerous folds/depressions on the cerebrum?
A
Gyri
13
Q
Spaces between gyri are called what?
A
Sulci
14
Q
What are the two types of grooves present on the brain?
A
Shallow: sulci
Deep and between each cerebral hemisphere and between the cerebrum and cerebellum: fissures
15
Q
What is the name of the fissure between the left and right cerebral hemispheres?
A
Longitudinal fissure
16
Q
What is the name of the fissure between the cerebrum and cerebellum?
A
Transverse fissure
17
Q
What are the names of the areas deep within each fissure of the brain?
A
Longitudinal: falx cerebri
Transverse: tentorium cerebelli
18
Q
The falx cerebri and tentorium cerebelli are formed by what?
A
Meninges; basically they are invaginations of the meningeal layer into the fissures
19
Q
What is the clinical relevance of the falx cerebri and tentorium cerebelli?
A
Great clinical relevance in terms of tumors
20
Q
What is the function of the falx cerebri and tentorium cerebelli?
A
Help compartmentalize the brain and keep it in its shape, as well as prevent intracranial pressure changes
21
Q
What is the largest portion of the brain?
A
Cerebrum/main brain/telencephalon
22
Q
What are the physiological divisions of the cerebrum?
A
- Frontal lobe
- Temporal lobe
- Parietal lobe
- Occipital lobe
- 5th lobe
23
Q
Describe the location and function of the frontal lobe.
A
- Most rostral portion
- Cognitive function as well as voluntary movement
24
Q
Describe the location and function of the temporal lobe.
A
- Lateral portion
- Sound recognition
25
Describe the location and function of the parietal lobe.
- Dorsal portion
- Taste and touch sensation
26
Describe the location and function of the occipital lobe.
- Caudal portion
- Vision
27
Describe the location and function of the 5th lobe.
- Deep within the hemispheres
- Consciousness, emotions, and taste/pain sensations
28
What is the name of the boundary between the frontal and parietal lobes of the cerebrum?
Central sulcus
29
What is the function of the central sulcus?
Helps to identify the precentral and postcentral gyri
30
What is the precentral gyrus?
Primary motor cortex of the brain that controls voluntary movement
31
What is the postcentral gyrus?
Sensory cortex of the brain that makes sense out of information that comes from the nerves (vision, sound, taste, touch, etc.)
32
What is the corpus callosum?
Structure comprised of large bundles of neuronal axons that allows communication between left and right hemispheres of the cerebrum and allows for the sharing of sensory, motor, and cognitive information between them
33
What are the components of the diencephalon?
- Thalamus
- Hypothalamus
- Epithalamus (pineal gland)
- Pituitary gland
34
What is the largest portion of the diencephalon?
Thalamus
35
Describe the thalamus.
- Consists of 2 oval masses of mainly grey matter that are connected by interthalamic adhesion
- Relay center of the cerebral cortex specifically
36
Describe the hypothalamus.
- Situated on the floor of the diencephalon beneath the thalamus
- Controls numerous vital functions such as temperature, GIT secretions, blood pressure, and GIT motility
37
Describe the epithalamus.
- Posterior to the thalamus
- Consists of the pineal gland and the habenula
38
What is the habenula?
Pair of small nuclei within the epithalamus that compresses the brain sensation to pain, helps with anxiety, sleep, etc.
39
What is the pineal gland?
Structure within the epithalamus that secretes melatonin, which is responsible for maintaining circadian rhythm
40
Describe the pituitary gland.
- Just beneath the hypothalamus and connected to it via the infundibular stalk
- Master gland/hypophysis
- Has anterior and posterior lobes
- Situated on the basisphenoid bone
41
What are the names of the anterior and posterior lobes of the pituitary gland?
Anterior: adenohypophysis
Posterior: neurohypophysis
42
What is the communication point between the anterior and posterior lobes of the pituitary gland?
Stalk
43
What is the relay center of the cerebral cortex?
Diencephalon
44
Where is the diencephalon situated?
Rostral to the brain stem between the cerebrum and the midbrain
45
On what bone is the fossa for the medulla oblongata?
Basioccipital
46
Describe the location of the cerebellum.
Caudal to the occipital lobe and transverse fissure and dorsal to the pons and medulla
47
What is the second largest division of the brain?
Cerebellum
48
How many fissures does the cerebellum have and what do they form?
Deep fissures that form lobes
Shallow fissures that form lobules/folia
49
What are the lobes formed by the deep fissures of the cerebellum?
- Anterior lobe: unconscious proprioception
- Posterior lobe: coordinates movement
- Flocculonodular lobe: controls reflex movement, eye movement, body equilibrium, and gait
50
What is another name for the flocculonodular lobe of the cerebellum?
Vestibulocerebellum since it is a part of the vestibular system of the brain
51
Describe the structure of the flocculonodular lobe of the cerebellum.
Consists of 2 flocculi connected by a central nodulus via thin pedicles
52
What is the name of the central part of the cerebellum?
Vermis
53
What are the characteristics of the vermis?
- Worm-like appearance
- Divided into rostral and caudal lobe
- Two lateral masses on either sides (cerebellar hemispheres)
- Responsible for the coordination of movement along the center of the body (trunk/head)
54
What is another name for the cerebellum according to its appearance?
Tree of life/arbor vitae due to the tracts of white matter that branch into the tissue and create the tree-like branching appearance
55
What are the characteristics of the brainstem?
- Bottom, stalk-like portion of the brain
- Consists of the midbrain, pons, and medulla oblongata
- Connects the brain to the spinal cord
- Contains many critical collections of white and grey matter
56
What is the role of the brainstem?
Connection point between brain and spinal cord and sends messages to the rest of the body to regulate many vital functions of life
57
The grey matter contained within the brain stem is made up of what?
Nerve cell bodies
58
What are the two parts of the midbrain?
Roof/dorsal portion called the tectum
Floor/ventral portion called the tegmentum
59
Describe the structure of the tectum of the midbrain.
Contains 4 round eminences called colliculi that collectively form what is called the corpora quadrigemina in which there are 2 rostral and 2 caudal
60
What are the roles of the 2 rostral and 2 caudal colliculi of the tectum of the midbrain?
Rostral: visual reflexes
Caudal: auditory reflexes
61
What is the only adult structure that arises from the mesencephalon?
Midbrain
62
What is the overall role of the midbrain?
Involved in certain reflexes associated with visual and auditory stimuli
63
Describe the pons.
Bulging structure on the ventral surface of the brainstem between the midbrain and the medulla that consists of several nuclei both motor and sensory
64
What are the names of cell bodies inside the CNS vs outside the CNS?
Inside: nuclei
Outside: ganglia
65
The pons contains nuclei for which cranial nerves?
Trigeminal, abducens, facial, and vestibulocochlear
66
What is the role of the pons?
Relay center for the cerebellum via pontine nuclei situated on the ventral portion of the pons
67
What is the name of the most caudal portion of the brain before it exits the foramen magnum as the spinal cord?
Medulla oblongata
68
The medulla is enclosed within which brain ventricle?
4th
69
The medulla contains nuclei for which cranial nerve?
Just the hypoglossal
70
What are the functions of the medulla?
- Contains cardiac and vasomotor centers: regulatory center for the rhythm of breathing, regulates heart rate, regulates diameter of blood vessels
- Coughing, swallowing, sneezing, and vomiting reflex centers contained here as well
71
A tumor in the area of the medulla oblongata would result in what signs?
- Respiratory failure
- Collapse of cardiovascular system
72
What are brain ventricles and how many are there?
Cavities within the brain tissue that are interconnecting; there are 4 of them
73
What are the names and locations of the 4 brain ventricles?
- Right lateral: right cerebral hemisphere
- Left lateral: left cerebral hemisphere
- 3rd: surrounded by diencephalon
- 4th: somewhere between the medulla and cerebellum and continues into the spinal cord
74
What is the role of the brain ventricles?
Secrete and circulate cerebrospinal fluid, which is responsible for shock absorption and maintaining intracranial pressure, and maintaining skull/brain barrier
75
What is the name of the structure that allows for communication between lateral ventricles and the 3rd ventricle?
Foramen of Monro (interventricular foramen)
76
What is the name of the structure that allows for communication between the 3rd ventricle and the 4th ventricle?
Aqueduct of Sylvius (cerebral aqueducts)
77
What is the name of the structure that allows for communication between the 4th ventricle and the subarachnoid space via the cisterna magna (spinal cord)?
Median aperture (foramen of Magendie)
78
What is the name of the structure that allows for communication between the 4th ventricle and the subarachnoid space via the cisterna of great cerebral vein (brain)?
Foramen of Luschka
79
What is hydrocephalus?
A condition in which there is a buildup of CSF within the brain that results in excess brain pressure; usually congenital due to a narrowing of the mesencephalic aqueduct
80
What are the signs of hydrocephalus?
- Ataxia, head pressing, nystagmus, circling, seizures
- Enlarged skull, bulging eyes, persistent soft spot (anterior fontanelle)
81
What are the predisposing factors for hydrocephalus?
- Small, brachycephalic breeds
- Young animals
82
What is the difference between encephalitis and hydrocephalus?
They both have the same clinical signs except for there is no skull enlargement with encephalitis
83
What is the management for hydrocephalus?
- Placement of a ventriculoperitoneal shunt to drain fluid from the brain to the spinal cord
- Omeprazole in mild cases
84
What are the 3 layers of the meninges?
- Pia mater: deepest, most delicate layer in which the tissues are invested into the brain
- Arachnoid mater: web-like middle layer
- Dura mater: thickest outer covering of the brain
85
What are the characteristics of the dura mater of the meninges?
- Forms the falx cerebri and the tentorium cerebelli
- 2 layers in the brain, 1 in spinal cord
- Blood supply from internal carotid artery
86
What are the spaces of the meninges?
- Subarachnoid space: between arachnoid mater and pia mater where CSF circulates; point of CSF collection
- Epidural space: between dura mater and wall of vertebral canal; point of administration of anesthesia
87
What does a drop test check for?
Negative pressure in the epidural space
88
What is important to remember when inserting a needle into the subarachnoid space for CSF collection?
Don't aspirate, let the fluid drip out
89
The limbic system is the part of the brain that is concerned with what?
Emotions, memories, sexual behaviors/stimulation, thirst, hunger, and fear/aggression
90
Where is the limbic system located?
Above the brainstem within the cerebrum
91
The limbic system is divided into what components?
Cortical component which contains the hippocampus and subcortical component
92
The hippocampus is involved with what?
Memory storage
93
Describe the course of all blood supply of the brain.
Starts ventrally, courses laterally and then dorsally
94
What % of the cardiac output goes to the brain?
20%, reduces after eating so that more blood is allocated to the GIT for digestion
95
What artery supplies blood to the external structures of the head?
External carotid artery, which is a division of the common carotid artery
96
What arteries are responsible for blood supply to the brain?
Caudal supply from the vertebral artery and rostral supply from the internal carotid artery with an anastomotic connection between rostral and caudal circulation
97
How does the vertebral artery course to the brain?
Passes through the transverse foramen starting at C6
98
Venous drainage from the head is through what 2 veins?
Internal and external jugular veins
99
Describe the compensatory system/collateral flow of blood supply in the brain.
If there is a blockage in the vertebral artery, the internal carotid can compensate via the circle of Willis, and vice versa
100
The circle of Willis is complete in what species?
Only in the dog, it is open rostrally in other mammals
101
True or false: the vertebral artery and internal carotid artery are in no way connected?
True
102
Describe the branching of the vertebral artery as it goes to the brain.
- Vertebral artery is a branch of the subclavian artery and enters the transverse foramen of C6 → travels toward the brain
- Spinal branches supply the spinal cord
- Occipital artery supplies head structures
- Meningeal branches supply the meninges
- Basilar artery: main branch of the vertebral artery that goes to the brain which is a fusion of the left and right vertebral arteries
103
What is the terminal branch of the vertebral artery?
Basilar artery
104
Describe the branching of the vertebral artery once it reaches the brain and becomes the basilar artery.
- Runs along the ventral surface of the pons and medulla
- At the level of the medulla it gives off branches called the caudal cerebellar arteries that supply the caudal portion of the cerebellum
- Then it forms the caudal communicating artery just rostral to the pons which forms the caudal portion of the circle of Willis
105
What are the branches of the caudal communicating artery of the brain?
- Rostral cerebellar arteries that supply the rostral portion of the cerebellum
- Just rostral to that is the caudal cerebral arteries which supply the caudal aspect of the cerebrum (diencephalon, mesencephalon, and caudomedial portion of the cerebral hemisphere/telencephalon) via the fissures (goes in transverse and comes out longitudinal)
106
Describe the branching of the internal carotid artery as it travels to the brain.
- It is a branch of the common carotid artery which is a branch of the brachiocephalic trunk
- Gives off the middle cerebral artery which courses lateral and rostral to supply the cerebral hemispheres
- Enters the skull and forms the rostral communicating artery which is the rostral portion of the circle of Willis
107
What artery branches off of the rostral communicating artery?
Rostral cerebral artery just rostral to the optic chiasm that courses rostrally and dorsally between the frontal lobes via the longitudinal fissure; gives blood supply to the rostral aspect of the brain and also the eye via the internal ophthalmic artery and internal ethmoidal artery
108
A blockage of the middle cerebral artery would largely affect which brain lobe?
Temporal lobe
