Chr. 14 - The Brain and Cranial Nerves Flashcards
(139 cards)
1
Q
[14.1] List the major parts of the brain.
A
Brainstem, cerebellum, diencephalon, cerebrum.
2
Q
[14.1] What are the cranial meninges?
A
The dura mater, arachnoid mater, and the pia mater.
3
Q
[14.1] List the extensions of the dura mater and which parts of the brain they separate.
A
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.
4
Q
[14.1] Describe the blood-brain barrier.
A
Endothelial cells of capillaries sealed together by tight junctions coupled with a thick basement membrane surrounding the capillaries. Selectively allows certain substances in blood to enter brain tissue.
5
Q
[14.2] Describe cerebrospinal fluid (CSF).
A
Clear, colourless liquid composed mainly of water. Carries oxygen, glucose, and other micronutrients from blood to nervous tissue. Circulates through cavities in the brain, spinal cord, and the subarachnoid space.
6
Q
[14.2] What are the cavities of the brain and where are they located?
A
Lateral Ventricles, two lateral ventricles each located in either hemisphere of the brain.
Third Ventricle, a narrow cavity along the midline above the hypothalamus and between the halves of the thalamus.
Fourth Ventricle, lies between the brainstem and cerebellum.
7
Q
[14.2] What is the septum pellucidum?
A
A thin membrane separating the anterior portions of the lateral ventricles.
8
Q
[14.2] List and describe the functions of CSF.
A
Mechanical protection, serves as shock-absorbing fluid and buoys the brain in the cranial cavity.
Chemical protection, provides optimal chemical environment for neuronal signaling.
Circulation, medium of exchange for nutrients and waste of nervous tissue.
9
Q
[14.2] Describe choroid plexuses.
A
Networks of blood capillaries in the walls of ventricles that produce CSF. Covered by ependymal cells featuring tight junctions that allow for bidirectional secretion. Tight junctions of the ependymal cells forces all material to pass through them instead of between cells.
10
Q
[14.2] What is the blood-cerebrospinal fluid barrier?
A
The barrier formed by ependymal cells and their tight junctions that protect the brain and spinal cord from harmful substances that would use CSF as a vector.
11
Q
[14.2] What are the interventricular foramina?
A
Two narrow oval openings of the lateral ventricles (one in each) that allow CSF to flow into the third ventricle.
12
Q
[14.2] What is the aqueduct of the midbrain?
A
A passage formed between the third ventricle and the fourth ventricle that passes through the midbrain.
13
Q
[14.2] What are the median and lateral apertures?
A
Median aperture, an opening in the roof of the fourth ventricle on the midline allowing CSF to circulate into the subarachnoid space.
Lateral apertures, openings on the lateral aspects of the fourth ventricle allowing CSF to circulate into the subarachnoid space.
14
Q
[14.2] Where is CSF formed?
A
In the choroid plexuses of each lateral ventricle, the choroid plexus in the roof of the third ventricle, and the choroid plexus of the fourth ventricle.
15
Q
[14.2] How is CSF reabsorbed?
A
Through arachnoid villi, extensions of the arachnoid mater the project into the dural venous sinuses.
16
Q
[14.2] What is the superior sagittal sinus?
A
A sinus located at the superior, posterior region of the brain.
17
Q
[14.2] What is an arachnoid granulation?
A
A cluster of arachnoid villi.
18
Q
[14.3] Describe the medulla oblongata.
A
A structure continuous with the spinal cord forming the inferior part of the brainstem. Begins at the foramen magnum and extends to inferior border of the pons. Contains all sensory and motor tracts extending between the brain and spinal cord.
19
Q
[14.3] What are the pyramids of the medulla?
A
Bulges of white matter formed by the corticospinal tracts passing from the cerebrum to the spinal cord.
20
Q
[14.3] What is the decussation of pyramids?
A
A crossing of axons to opposite sides of the body just above the junction of the medulla and spinal cord.
21
Q
[14.3] List and describe the nuclei of the medulla.
A
Cardiovascular center, regulates rate and force of heartbeat as well as diameter of blood vessels.
Medullary respiratory center, adjusts basic rhythm of breathing.
Vomiting center, causes vomit reflex.
Deglutition center, promotes deglutition when stimulated.
Gustatory nucleus, part of the gustatory sensory pathway.
Cochlear nuclei, part of the auditory sensory pathway.
Vestibular nuclei, components of the equilibrium sensory pathway.
22
Q
[14.3] What are medullary olives?
A
Oval-shaped swellings lateral of pyramids that contain the inferior olivary nucleus.
23
Q
[14.3] What is the inferior olivary nucleus?
A
A nucleus of the medulla oblongata that receives input from the cerebral cortex, red nucleus of the midbrain, and spinal cord. Neurons in the nucleus extend their axons into the cerebellum to regulate cerebellar neurons.
24
Q
[14.3] What are the gracile nuclei and cuneate nucleus?
A
Nuclei located on both posterior sides of the medulla that are associated with sensations of touch, pressure, vibration, and conscious proprioception. Form synapses with axons from the spinal cord and relay information to the thalamus.
25
[14.3] What is the medial lemniscus?
Myelinated axons of the gracile and cuneate nucleus that ascend to the thalamus, decussating shortly after extending from the neural soma in the nucleus.
26
[14.3] What is the posterior column-medial lemniscus pathway?
A pathway formed by the tracts of the posterior columns and the axons of the medial lemniscus.
27
[14.3] Describe the pons.
A structure of the brainstem laying directly superior to the medulla and anterior to the cerebellum. Consists of both nuclei and tracts, and mainly functions to connect parts of the brain with one another.
28
[14.3] What are the main regions of the pons?
A ventral region and a dorsal region.
29
[14.3] What is the pontine nuclei?
A large synaptic relay station of scattered grey centers in the ventral region synapsing with numerous white matter tracts. Essential role in coordinating and maximizing efficiency of voluntary motor output.
30
[14.3] What is the pontine respiratory group?
A nucleus that works in tandem with the medullary respiratory center to control breathing.
31
[14.3] Describe the midbrain.
A structure of the brainstem that extends from the pons to the diencephalon. Contains nuclei and tracts.
32
[14.3] What are the cerebral peduncles?
Paired bundles of axons of the corticospinal, corticobulbar, and corticopontine tracts. They conduct nerve impulses from the cerebral cortex to the spinal cord, medulla, and pons respectively.
33
[14.3] What is the tectum?
The posterior part of the midbrain and contains four rounded elevations.
34
[14.3] What are the superior colliculi?
The two superior elevations of the tectum that serve as reflex centers for visual activities. Innervate extrinsic eye muscles and skeletal muscles of head, neck, and trunk in responses to visual activity.
35
[14.3] What are the inferior colliculi?
The two inferior elevations of the tectum that relay impulses from auditory sensory receptors to the brain and include auditory reflexes.
36
[14.3] What are the substantia nigra?
Two nuclei, one on each side of the midbrain, that release dopamine and help control subconscious muscle activity.
37
[14.3] What are the red nuclei?
Nuclei, one in each side of the midbrain, aiding to control muscular movement by synapsing with axons from the cerebellum and cerebral cortex.
38
[14.3] What is the reticular formation?
A broad region where white and grey matter form a net-like arrangement extending from the superior portion of the spinal cord to the inferior part of the diencephalon. Responsible for consciousness, attention, and awakening. Prevents sensory overload.
39
[14.3] What is the reticular activating system?
The ascending portion of the reticular formation consisting of sensory axons projecting to the cerebral cortex.
40
[14.4] Describe the cerebellum.
A mass of nervous tissue forming the posterior/inferior portion of the brain. Contains folds increasing surface area. Rests posterior to the medulla/pons.
41
[14.4] What is the transverse fissure?
A deep groove separating the cerebellum from the cerebrum and containing the tentorium cerebelli.
42
[14.4] What is the tentorium cerebelli?
A membrane supporting the posterior cerebrum and separating the cerebellum from the cerebrum.
43
[14.4] What is the vermis of the cerebellum.
The central constricted area of the cerebellum.
44
[14.4] What are the cerebellar hemispheres?
Lateral portions of the cerebellum that resemble wings.
45
[14.4] What is the purpose of the anterior and posterior lobe of the cerebellum?
To govern subconscious aspects of skeletal muscle movement.
46
[14.4] What is the cerebellar cortex?
The superficial layer of the cerebellum consisting of grey matter in slender, parallel folds called folia.
47
[14.4] What is the arbor vitae?
Tracts of white matter deep to the cerebellar cortex.
48
[14.4] What are the cerebellar nuclei?
Regions of grey matter deep to the arbor vitae that extend axons to other brain centers.
49
[14.4] What are the cerebral peduncles?
Bundles of white matter attaching the cerebellum to the brainstem, with extending axons that link the cerebellum to other regions of the brain.
50
[14.4] What are the superior cerebellar peduncles?
Peduncles of the cerebellum resting superior to the others that extend axons to the red nuclei of the midbrain and several nuclei in the thalamus.
51
[14.4] What are the middle cerebellar peduncles?
Bundle of axons extending from the pontine nuclei to the cerebellum carrying impulses for voluntary movements.
52
[14.4] What are the inferior cerebral peduncles?
Paired bundles of white matter made of five axon groups:
- Axons from spinocerebellar tract carrying proprioceptive information of the body
- Axons from the vestibular apparatus and vestibular nuclei of medulla and pons
- Axons from the inferior olivary nucleus of medulla regulating cerebellar neurons
- Axons from the cerebellum to vestibular nuclei of medulla and pons
- Axons from the cerebellum extending to the reticular formation
53
[14.5] Describe the diencephalon.
The central core of brain tissue superior of the midbrain and surrounded by the cerebral hemispheres and contributes to a wide variety of sensory and motor processing between higher and lower brain centers. Consists of the thalamus, hypothalamus, and epithalamus.
54
[14.5] Describe the thalamus.
A pair of oval masses of grey matter organized into nuclei with interspersed tracts of white matter.
55
[14.5] What is the interthalamic adhesion?
A bridge of grey matter joining the right and left halves of the thalamus.
56
[14.5] What is the internal medullary lamina?
A vertical Y-shaped sheet of white matter dividing the grey matter of each lobe of the right and left sides of the thalamus.
57
[14.5] What is the internal capsule of the thalamus?
A thick band of white matter lateral to the thalamus containing axons connecting the thalamus and cerebral cortex.
58
[14.5] List the major groups of the nuclei on each of the thalamus.
1. Anterior nucleus
2. Medial nucleus
3. Lateral group
4. Ventral group
5. Intralaminar group
6. Midline nucleus
7. Reticular nucleus.
59
[14.5] What is the function of the anterior nucleus of the thalamus?
Receives input from hypothalamus and outputs to the limbic system. Functions in emotions and memory.
60
[14.5] What is the function of the medial nuclei?
Receives input from the limbic system and basal nuclei; outputs to cerebral cortex. Functions in emotions, learning, memory, cognition.
61
[14.5] What is the function of the lateral group?
Relays input from the limbic system, superior colliculi, and the cerebral cortex, to the cerebral cortex.
62
[14.5] What is the function of the intralaminar nuclei?
Connect the reticular formation, cerebellum, basal nuclei, and wide areas of the cerebral cortex. Function in arousal and integration of sensory and motor information.
63
[14.5] What is the function of the midline nucleus?
Forms a thin band of nervous tissue. Presumed function in memory and olfaction.
64
[14.5] What is the function of reticular nucleus?
Surrounds lateral aspect of thalamus next to internal capsule. Functions to monitor, filter, and integrate activity of other thalamic nuclei.
65
[14.5] Describe the hypothalamus.
A small portion of the diencephalon located inferior to the thalamus, composed of four major regions and functions to control many body activities and regulates homeostasis.
66
[14.5] What are the four major region of the hypothalamus.
Mammillary region, tuberal region, supraoptic region, and preoptic region.
67
[14.5] Describe the mammillary region of the hypothalamus.
Most posterior part of the hypothalamus, serves as relay station for reflexes stemming from sense of smell.
68
[14.5] Describe the tuberal region of the hypothalamus.
Widest portion of the hypothalamus, composed of, among other things, the infundibulum which connects the pituitary gland to the hypothalamus, and the median eminence, a slightly raised region encircling the infundibulum.
69
[14.5] Describe the important functions of the hypothalamus.
Control of the ANS, regulates contraction of smooth muscle and cardiac muscle as well as secretions of glands.
Production of hormones, produces and secretes releasing hormones and inhibiting hormones, as well as oxytocin an ADH.
Regulation of emotional and behavioural patterns, participates in expressions of rage, aggression, pain, and pleasure.
Regulation of eating and drinking, contains a feeding center, satiety center, and thirst center that regulate these three activities.
Control of body temperature, monitors temperature of blood flowing to the hypothalamus and stimulates metabolism to adjust.
Regulation of circadian rhythms, establishes patterns of biological activity from visual input.
70
[14.5] Describe the epithalamus.
A small region superior and posterior of the thalamus consisting of the pineal gland and the habenular nuclei.
71
[14.5] Describe the pineal gland.
A small protuberance from the midline of the third ventricle, secretes melatonin to assist in maintaining circadian rhythm.
72
[14.5] Describe the habenular nuclei.
Nuclei involved in olfaction and emotional response to odours.
73
[14.5] What are circumventricular organs?
Parts of the diencephalon that lie in the wall of the third ventricle to monitor chemical changes in blood due to absence of the BBB.
74
[14.6] Describe the cerebrum.
Nervous tissue surrounding the diencephalon, consisting of an outer cerebral cortex, internal region of cerebral white matter, and grey matter nuclei deep within the grey matter. Divided into cerebral hemispheres and separated by the corpus callosum.
75
[14.6] Describe the cerebral cortex.
The region of grey matter that forms the outer rim of the cerebrum, containing gyri, fissures, and sulci.
76
[14.6] What are gyri?
Folds of the cerebral cortex.
77
[14.6] What are fissures and sulci in regards of the cerebral cortex?
Deep grooves and shallow grooves respectfully between gyri.
78
[14.6] What is the longitudinal fissure?
The most prominent fissure separating the cerebrum into hemispheres.
79
[14.6] What is the corpus callosum?
A broad band of white matter connecting hemispheres of the cerebrum.
80
[14.6] What is the central sulcus?
A sulcus dividing the frontal lobe and the parietal lobe.
81
[14.6] What is the precentral gyrus?
A major gyrus located anterior to the central sulcus containing the primary motor area.
82
[14.6] What is the postcentral gyrus?
A major gyrus located posterior to the central sulcus containing the somatosensory area of the cerebral cortex.
83
[14.6] What is the lateral cerebral sulcus?
A major sulcus separating the temporal lobe from the frontal lobe.
84
[14.6] What is the parieto-occipital sulcus?
A major sulcus separating the occipital lobe from the parietal lobe.
85
[14.6] What is the insula?
A fifth part of the cerebrum lying within the lateral cerebral sulcus.
86
[14.6] What are the types of cerebral white matter tracts?
Association tracts, commissural tracts, and projection tracts.
87
[14.6] What are association tracts?
Tracts containing axons conducting nerve impulses between gyri in the same hemisphere.
88
[14.6] What are commissural tracts?
Tracts containing axons conducting impulses between corresponding gyri in one hemisphere to the other. The corpus callosum is the largest example.
89
[14.6] What are projection tracts?
Tracts containing axons that conduct impulses from the cerebrum to lower parts of the CNS.
90
[14.6] What is the internal capsule?
A thick band of white matterin each hemisphere classified as a projection tract containing ascending and descending axons and separating both the thalamus and caudeate nucleus from the putamen and globus pallidus.
91
[14.6] What are basal nuclei?
Three nuclei deep within each cerebral hemisphere.
92
[14.6] What are the functions of basal nuclei?
To receive input from the cortex and provide output to effectors via medial and ventral nuclei in the thalamus. Also regulate initiation and termination of movement.
93
[14.6] List the basal nuclei of the cerebrum.
Globus pallidus, putamen, and the caudate nucleus.
94
95
[14.6] What is the corpus striatum?
A structure consisting of the lentiform nucleus (globus pallidus and putamen) and caudate nucleus.
96
[14.6] What is the claustrum?
A thin sheet of grey matter situated lateral to the putamen.
97
[14.6] What is the limbic system?
A ring of structures on the inner border of the cerebrum and the floor of the diencephalon.
98
[14.6] What is the limbic lobe?
The rim of the cerebral cortex on the medial surface of each hemisphere composed of the cingulate gyrus and the parahippocampal gyrus.
99
[14.6] What is the dentate gyrus?
A gyrus involved in the limbic system lying between the hippocampus and the parahippocampal gyrus.
100
[14.6] What is the amygdala?
A structure involved in the limbic system composed of several groups of neurons located near the end of the caudate nucleus.
101
[14.6] What are the septal nuclei?
Nuclei involved in the limbic system located within the septal area underneath the corpus callosum and the paraterminal gyrus.
102
[14.6] What are the mammillary bodies?
Two round masses of the hypothalamus close to the midline and cerebral peduncles.
103
[14.6] What are the olfactory bulbs?
Flattened bodies of the olfactory pathway resting on the cribiform plate.
104
[14.6] What are the linked bundles of interconnecting myelinated axons contained in the limbic system?
The fornix, stria terminalis, stria medullaris, medial forebrain bundle, and the mammillothalamic tract.
105
[14.7] What are the important primary sensory areas of the cerebral cortex?
Primary somatosensory area, primary visual area, primary auditory area, primary gustatory area, and primary olfactory area.
106
[14.7] Describe the primary somatosensory area.
Located directly posterior to the central sulcus of cerebral hemispheres. Receives and integrates information for all somatic senses and forms a sensory map of the body known as the sensory homunculus.
107
[14.7] Describe the primary auditory area.
Located in the superior part of the temporal lobe, receives impulses generated from auditory sensory receptors.
108
[14.7] Describe the primary gustatory area.
Located in the insula, receives impulses from gustatory perception and sensory receptors.
109
[14/.7] Describe the primary olfactory area.
Located in the medial temporal lobe, receives impulses from olfactory sensory receptors.
110
[14.7] What are the important motor areas of the cerebral cortex?
The primary motor area and Broca's speech area.
111
[14.7] Describe the primary motor area.
Located in the precentral gyrus of the frontal lobe, this area is responsible for voluntary contractions and forms a distorted muscle map of neurons known as the motor homunculus.
112
[14.7] Describe Broca's speech area.
Located in the frontal lobe close to the lateral cerebral sulcus, this area is responsible for speaking and understanding language.
113
[14.7] List the important association areas.
Somatosensory association area
Visual association area
Facial recognition area
Auditory association area
Orbitofrontal area
Wenicke's area
Common integrative area
Prefrontal cortex
Premotor area
Frontal eye field area.
114
[14.7] Describe the somatosensory association area.
Posterior to the primary somatosensory area, integrates and analyzes sensory information from the primary somatosensory area and stores memories associated with touch.
115
[14.7] Describe the visual association area.
Located in the occipital lobe, integrates and analyzes visual sensory information from the primary visual area and stores memory associated with vision
116
[14.7] Describe the facial recognition area.
Located in the inferior temporal lobe, integrates visual sensory information regarding faces.
117
[14.7] Describe the auditory association area.
Located posterior and inferior to the primary auditory area integrating and analyzing auditory sensory information from the primary auditory area.
118
[14.7] Describe the orbitofrontal cortex.
Located along the lateral frontal lobe, integrates and analyzes information from the primary olfactory area.
119
[14.7] Describe Wernicke's area.
A broad region in the temporal and parietal lobes of the left hemisphere that recognizes and interprets meanings of speech
120
[14.7] Describe the common integrative area.
Receives and integrates information from the primary gustatory area, the primary olfactory area, the thalamus, and parts of brainstem. Responsible for formation of thoughts and generates signals based on information input.
121
[14.7] Describe the prefrontal cortex.
An extensive area in the anterior frontal lobe connecting with all major regions of the brain and is responsible for intellect, personality, cognition, conscious, emotion, and abstractive abilities.
122
[14.7] Describe the premotor area.
A motor association area anterior to the primary motor area. Communicates with primary motor cortex, sensory association areas, basal nuclei, and the thalamus to learn motor activities of complex and sequential nature.
123
[14.7] Describe the frontal eye field area.
Controls voluntary scanning movements of eyes.
124
[14.7] Describe hemispheric lateralization.
Functional asymmetry allowing the hemispheres of the brain to specialize in specific functions.
125
[14.7] What are brain waves?
Electrical signals generated in brain tissue generated by neurons close to the surface.
126
[14.8] What are special sensory, motor, and mixed cranial nerves?
Special sensory nerves are unique to the head and are associated with smelling, seeing, and hearing.
Motor nerves contain only axons of motor neurons.
Mixed nerves contain axons of both sensory and motor neurons.
127
[14.9] Name and describe Cranial Nerve I.
Olfactory (I) Nerve. A paired special sensory nerve originating in olfactory epithelium of the superior nasal cavity and extending through the cribriform plate into the olfactory bulbs - masses of brain tissue resting on the cribriform plate. The olfactory tract extends from the olfactory bulbs into the cerebrum.
128
[14.10] Name and describe Cranial Nerve II.
Optic (II) Nerve. A paired special sensory nerve forming when all ganglion cells of a retina converge before passing through the optic foramen. The Optic (II) nerves merge to form the optic chiasm where they decussate and split, forming the optic tract until they integrate with the primary visual area of the cerebral cortex.
129
[14.11] Name and describe Cranial Nerve III
Oculomotor (III) Nerve. A nucleus exists in the anterior midbrain and divides into superior and inferior branches that both pass through the orbital fissure. Responsible for most somatic movement of the eye and the movement of the smooth muscle of the eye.
130
[14.11] Name and describe Cranial Nerve IV.
Trochlear (IV) nerve. Motor nerve arising in the posterior brainstem, innervate the superior oblique muscle of the eye.
131
[14.12] Name and describe Cranial Nerve V.
Trigeminal (V) Nerve. Mixed nerve originating from two roots on the anterolateral surface of pons. Contains a swelling termed the trigeminal ganglion located on the temporal bone. Contains three branches.
132
[14.12] Name the three branches of the Trigeminal (V) Nerve.
Opthalmic nerve
Maxillary nerve
Mandibular nerve
133
[14.11] Name and describe Cranial Nerve VI.
Abducens (VI) nerve. Motor nerve arsing in the pons extending to the lateral rectus of the eye.
134
[14.13] Name and describe Cranial Nerve VII.
Facial (VII) nerve. Mixed cranial nerve originating in the taste buds of anterior two thirds of tongue and extending to the geniculate ganglion in the temporal bone, which then extends through the pons to the thalamus and ultimately the gustatory area of the cerebral cortex.
135
[14.14] Name and describe Cranial Nerve VIII.
Vestibulocochlear (VIII) nerve. Special sensory nerve containing two branches:
Vestibular branch which originates in the semicircular canals, saccule, and utricle of the inner ear and runs through the pons to the cerebellum. Responsible for equilibrium.
The cochlear branch originates in the spiral organ and runs through the medulla oblongata into the thalamus. Responsible for hearing.
136
[14.15] Name and describe Cranial nerve IX.
Glossopharyngeal (IX) nerve. Mixed nerve with the sensory nerve originating in the posterior third of tongue and several sensory/chemical receptors related and travel to the medulla through the superior and inferior ganglia. . The motor nerve originates in the medulla and innervate swallowing and saliva glands through the otic ganglion.
137
[14.16] Name and describe Cranial Nerve X.
Vagus (X) Nerve. Mixed cranial nerve with the sensory originating in several locations: same as IX as well as visceral sensory receptors from the thorax and abdomen. Sensory nerve ends in the medulla and pons.
138
[14.17] Name and describe Crnial Nerve XI.
Accessory (XI) Nerve. Motor nerve originating in the anterior grey horn of C1 - C5 and extend into the foramen magnum, exit through the jugular foramen, and innervate the sternocleidomastoid and trapezius.
139
[14.18] Name and describe Cranial Nerve XII.
Hypoglossal (XII) Nerve. Motor nerve originating in medulla oblongata and exits through the hypoglossal canal innervating impulses for speech and swallowing.
