EXAM 2 BRAIN AND CRANIAL NERVES Flashcards
(105 cards)
1
Q
What are meninges?
A
Three membranes surrounding brain and spinal cord
2
Q
What is the function of the meninges?
A
Protect the brain and provide structural framework for its arteries and veins
3
Q
What are the three meninges from most superficial to most deep?
A
Dura mater
Arachnoid mater
Pia mater
4
Q
Dura mater
A
- presses closely against cranial bones
- no epidural space (unlike spinal cord)
- not directly attach to bone except around foramen magnum, sella turcica, crista Gallo, and sutures of the skull
5
Q
Folds of dura mater extend inward, separating some brain regions into the folllowing
A
- falx cerebri: separates the 2 cerebral hemispheres
- tentorium cerebelli: separates cerebrum from cerebellum
- falx cerebelli: separates right left halves of cerebellum
6
Q
Arachnoid mater
A
- transparent membrane over brain surface
- subarachnoid space separates it from pia mater below
7
Q
Pia mater
A
- very thin membrane, not usually visible without microscope
- follows all contours of brain
- follows arteries as they penetrate into cerebrum
8
Q
What is the brain protected by?
A
At the blood capillaries, the brain is protected by the blood-brain barrier
9
Q
What makes up the blood-brain barrier?
A
Consists of tight junctions between endothelial cells that form the capillary walls
10
Q
What is the process of the blood-brain barrier?
A
- During development, astrocytes reach out no contact capillaries with their perivascular feet
- this induces the endothelial cells to form tight junctions that completely seal off gaps between them
11
Q
Anything leaving the blood must pass through what?
A
Anything leaving the blood must pass through the cells and not the gaps between them
12
Q
What can endothelial cells be unlike simple gaps?
A
Endothelial cells can be selective unlike simple gaps
13
Q
What are the 4 lobes that make up the brain?
A
- frontal lobe
- parietal lobe
- occipital lobe
- temporal lobe
14
Q
What is the function of the frontal lobe?
A
Voluntary motor functions, motivation, foresight, planning, memory, mood, emotion, social judgement, and aggression
15
Q
What are the functions of the parietal lobe?
A
Integrates general senses, taste, and some visual info
16
Q
What is the function of the occipital lobe?
A
Primary visual center of brain
17
Q
What is the function of the temporal lobe?
A
Functions in hearing, smell, learning, memory, and some aspects of vision and emotion
18
Q
What is the function of insula (hidden by other regions)?
A
Helps in understanding spoken language, taste and integrating info from visceral receptors
19
Q
What is the primary sensory cortex?
A
Sites where sensory input is first received and one becomes conscious of the stimulus
20
Q
What is the primary visual cortex?
A
Bordered by visual association areas: make cognitive sense of visual stimuli
21
Q
What are multimodal association areas?
A
Receive input from multiple senses and integrate this into an overall perception of our surroundings
22
Q
What are pyramidal cells of the precentral gyrus called?
A
Upper motor neurons
23
Q
Things about upper motor neurons
A
- their fibers project caudally
- about 10 million fibers ending in nuclei of the brainstem
- about 1 million forming the corticospinal tracts
- most fibers decussate in lower medulla oblongata
- form lateral corticospinal tracts on each side of the spinal cord
24
Q
In brainstem or spinal cord the fibers from upper motor neurons synapse with what?
A
Lower motor neurons whose axons innervate skeletal muscles
25
Where is Wernicke area located?
-posterior to lateral sulcus usually in left hemisphere
26
Where is Broca area located?
Inferior prefrontal cortex usually in left hemisphere
27
Broca area generated motor programs for the muscles of
- larynx
- tongue
- cheeks
- lips for speaking and for hands when signing
28
Function of Broca area
Transmits program to primary motor cortex for commands to the lower motor neurons that supply relevant muscles
29
Function of Wernicke area
- permits recognition of spoken and written language
| - when we intend to speak, Wernicke area formulated phrases and transmits plan of speech to Broca area
30
Where is affective language area?
Usually in right hemisphere
31
What do lesions produce in Broca area?
Aprosody (flat emotionless speech)
32
What are the three parts of the diencephalon?
- thalamus
- hypothalamus
- epithalamus
33
Thalamus of the diencephalon
- ovoid mass on each side of the brain
- perched at the superior end of the brainstem beneath the cerebral hemispheres
- constitutes about 4/5 of the diencephalon
- composed of at least 23 nuclei within 5 major functional groups
34
What function does thalamus have in diencephalon?
Plays key role in motor control
-relays signals from cerebellum to cerebrum
-provides feedback loops between the cerebral cortex and the basal nuclei
Involved in memory and emotion
-limbic system includes some of the anterior thalamus nuclei
35
Hypothalamus is major control center of what systems?
Autonomic nervous system and endocrine system
36
What are the functions of hypothalamic nuclei?
Hormone secretion
-controls anterior pituitary, thereby regulating growth, metabolism, reproduction, and stress responses
Autonomic effects
-major integrating center for autonomic nervous system
-influences heart rate, blood pressure, gastrointestinal secretions, motility, etc
37
What are the hypothalamic functions?
Thermoregulation
Food and water intake
-regulates hunger and satiety; responds to hormones influencing hunger, energy expenditure, and long-term control of body mass
-thirst center monitors osmolarity of blood and can stimulate production of anti diuretic hormone
Sleep and circadian rhythms
-suprachiasmatic nucleus sits above optic chiasm
Memory
-mammillary nuclei receive signals from hippocampus
Emotional behavior and sexual response
-anger, aggression, fear, pleasure, contentment, sexual drive
38
What is the epithalamus of the diencephalon composed of?
- pineal gland: endocrine gland
- habenula: relay from the limbic system to the midbrain
- thin roof over the third ventricle
39
Cranial Nerves
Brain must communicate with rest of body
- 12 pairs of cranial nerves arise from the base of the brain
- exit the cranium through foramina
- lead to muscles and sense organs located mainly in the head and neck
40
Where do most motor fibers of the cranial nerves begin?
In nuclei of brainstem and lead to glands and muscles
41
Where do sensory fibers begin and lead to?
Sensory fibers begin in receptors located mainly in head and neck and lead mainly to the brainstem
42
Most cranial nerves carry fibers between the brainstem and what receptors and effectors?
Ipsilateral receptors and effectors
43
Lesion in brainstem causes sensory or motor deficit on same side except
- optic nerve- half the fibers decussate
| - trochlear nerve-all efferent fibers lead to a muscle of the contralateral eye
44
Sensory cranial nerves include
I (1), II (2), and VIII (8)
45
Motor cranial nerves include
III (3), IV (4), VI (6), XI (11), and XII (12)
46
Both (mixed) cranial nerves include
V (5), VII (7), IX (9), and X (10)
47
Motor cranial nerves stimulate muscle but also…
Contain fibers of proprioception
48
What nerve is Cranial nerve 1
Olfactory nerve
49
What is the sensory function of cranial nerve 1 olfactory nerve?
Sense of smell
50
What is the origin of cranial nerve 1 olfactory nerve?
Receptors (bipolar neurons) in olfactory epithelium of nasal cavity
51
What is cranial nerve 2?
Optic nerve
52
What is the sensory function of cranial nerve 2 optic nerve?
Sense of sight
53
What is the origin of cranial nerve 2 optic nerve?
Retina of the eye
54
What is cranial nerve 3?
Oculomotor nerve
55
What is the motor function of cranial nerve 3 oculomotor nerve?
- eyeball movements via extrinsic muscles
- adjusting lens
- pupil constriction
56
Oculomotor nerve contains only motor axons as they exit out the brainstem and make their way to the eye the axons divide into 2 branches
Superior branch
-inner area the superior rectus and Lea toe palpebrae superioris
Interior branch
-somatic neurons: innervates the medial and inferior recti muscles and the inferior oblique muscles using somatic motor neurons
-autonomic neurons: supplies parasympathetic innervation to the ciliary muscle of the eyeball, which adjusts the lens for near vision and the circular muscles of the iris, which cause the pupil to constrict under bright light conditions
57
What is the origin of cranial nerve 3 oculomotor nerve?
Oculomotor and Edinger Westphal nuclei within the midbrain
58
What is cranial nerve 4?
Trochlear nerve
59
What is the motor function of cranial nerve 4 trochlear nerve?
Eyeball movement
60
What is the origin of cranial nerve 4 trochlear nerve?
Trochlear nucleus within the midbrain
61
What is cranial nerve 5?
Trigeminal nerve
62
What is the largest cranial nerve?
Trigeminal nerve
63
What are the three branches of the trigeminal nerve?
- ophthalmic nerve
- maxillary nerve
- mandibular nerve
64
Where does the ophthalmic nerve of the trigeminal nerve get its sensory info from?
Skin over upper eyelid, lacrimal glands, upper part of nasal cavity, side of the nose, forehead, and anterior half of the scalp
65
Where does the maxillary nerve of the trigeminal nerve get its sensory info from?
mucosa of the nose, palate, part of the pharynx, upper teeth, upper lip, and lower eyelid
66
Where does mandibular nerve of the trigeminal nerve gets its sensory info from?
Sensory info from anterior 2/3 of the tongue, cheek, lower teeth, skin over the mandible, and side of the head anterior to the ear
67
Where does the mandibular nerve of the trigeminal nerve motor info get sent to?
Motor info to muscles of mastication to carry out the act of chewing
68
What is the origin of the trigeminal nerve?
Nuclei in the pons
69
What is cranial nerve 6?
Abducens nerve
70
What is the motor function of cranial nerve 6 abducens nerve?
- eye movements
| - together with oculomotor (CN III) and trochlear (CN IV)
71
What is the origin of cranial nerve 6 abducens nerve?
Pontine (abducens) nucleus in the pons
72
What is cranial nerve 7?
Facial nerve
73
What is the sensory function of cranial nerve 7 facial nerve?
- taste
- touch
- pain
- thermal sensation
74
What is the motor function of cranial nerve 7 facial nerve?
- Muscles for facial expressions
| - Secretion of saliva and tears
75
What are the 5 branches of cranial nerve 7 facial nerve?
- temporal
- zygomatic
- buccal
- mandibular
- cervical
76
What is the origin of cranial nerve 7 facial nerve?
Nuclei in the pons
77
What is cranial nerve 8?
Vestibulocochlear nerve
78
What are the sensory functions of cranial nerve 8 vestibulocochlear nerve?
- hearing
| - equilibrium
79
What is the origin of cranial nerve 8 vestibulocochlear nerve?
Vestibular branch: hair cells in the vestibule of the inner ear
Cochlear branch: cochlea of the inner ear
80
What is cranial nerve 9?
Glossopharyngeal nerve
81
What are the sensory functions of cranial nerve 9 glossopharyngeal nerve?
- taste
- swallowing proprioception
- monitoring blood pressure
- O2/CO2 levels
- touch, pain, and thermal sensation (ears and throat)
82
What are the motor functions of cranial nerve 9 glossopharyngeal nerve?
- swallowing
| - saliva secretion
83
What is the origin of cranial nerve 9 glossopharyngeal nerve?
Sensory axons originate on taste buds and mucosa of posterior 1/3 of tongue, as well as the carotid bodies.
Motor axons originate in nuclei in the medulla oblongata
84
What is cranial nerve 10?
Vagus nerve
85
What are the sensory functions of cranial nerve 10 vagus nerve?
- taste from epiglottis
- proprioception of throat and voice box muscles
- monitoring of blood pressure and O2/CO2 levels
- touch-pain-thermal sensations of ear
- sensations from thoracic organs
86
What are the motor functions of cranial nerve 1 vagus nerve?
- swallowing
- vocalization
- coughing and autonomic motility of secretions of the gastrointestinal organs
- constriction of respiratory pathways
- decrease in heart rate
87
What is the origin of cranial nerve 10 vagus?
Motor nuclei in medulla oblongata
88
What is cranial nerve 11?
Accessory nerve
89
What is the motor function of cranial nerve 11 accessory nerve?
Movement of head
90
What is the origin of cranial nerve 11 accessory nerve?
Cranial root: nucleus in medulla oblongata
| Spinal root: nucleus in spinal cord
91
What is cranial nerve 12?
Hypoglossal nerve
92
What are the motor functions of cranial nerve 12 hypoglossal nerve?
- speech
- manipulation of food
- swallowing
93
What is origin of cranial nerve 12 hypoglossal nerve?
Hypoglossal nucleus in medulla oblongata
94
What number is olfactory nerve?
CN I (1)
95
What number is optic nerve?
CN II (2)
96
What number is oculomotor nerve?
CN III (3)
97
What number is trochlear nerve?
CN IV (4)
98
What number is trigeminal nerve?
CN V (5)
99
What number is abducens nerve?
CN VI (6)
100
What number is facial nerve?
CN VII (7)
101
What number is vestibulocochlear nerve?
CN VIII (8)
102
What number is glossopharyngeal nerve?
CN IX (9)
103
What number is vagus nerve?
CN X (10)
104
What number is accessory nerve?
CN XII (11)
105
What number is hypoglossal nerve?
CN XII (12)
