Gross Brain, Brainstem, and Spinal Cord (Dennis) Flashcards
1
Q
- the brain consists of the forebrain, midbrain, and hindbrain
- forebrain consists of _____ _______ and deep structures
- midbrain = midbrain
- hindbrain consists of the ____, ______, and ________
- midbrain and hindbrain collectively are the _______
- there is a bend in the brain, thus various directional terms are used, what are these terms? (brain and brainstem can have different planes of section)
A
- the brain consists of the forebrain, midbrain, and hindbrain
- forebrain consists of cerebral hemispheres and deep structures
- midbrain = midbrain
- hindbrain consists of the pons, medulla, and cerebellum
- midbrain and hindbrain collectively are the brainstem
- there is a bend in the brain, thus various directional terms are used, what are these terms? (brain and brainstem can have different planes of section)
- planes of section are highlighted in the image
2
Q
- cerebral hemispheres have folding to increase surface area
- what is the terminology associated with this folding?
A
- gyrus: ridge of cortical tissue
- sulcus: groove located between gyri
- fissures: particularily deep sulci
- appearance of gyri and sulci can vary, but major features are pretty constant
3
Q
- areas containing neuronal/glial cell bodies and dendrites
A
gray matter
4
Q
collections of cell bodies w/ a common function
A
nuclei
5
Q
layers of gray matter over other parts of the CNS (i.e. cerebral and cerebellar cortices)
A
cortex
6
Q
- areas where there is a collection of axons, may covered w/ myelin
- other names: fasciculus, funiculus, lemniscus, peduncle, and tract
- most tracts have 2-part names: 1st part is the location of neuronal cell bodies from which axons originate, 2nd part is the site where axons terminate
A
white matter
7
Q
What divides the cerebral hemispheres and what are the names of these structures?
A
- sulci divide each hemisphere
- central sulcus
- lateral sulcus (fissure)
- parietooccipital sulcus
- cingulate sulcus
8
Q
What are the borders and functions of the frontal lobe?
A
- separated from parietal lobe by central sulcus and temporal lobe by lateral fissure
- precentral gyrus: primary motor areas
- lateral and medial surfaces: voluntary motor behavior and deciding which movements should be performed
- lateral surface: motor aspects of language
- prefrontal association areas: emotion, motivation, personality, initiative, judgement, ability to concentrate, and social inhibitions
- cingulate gyrus: modulates emotional aspects of behavior
9
Q
What are the structural features and general functions of the parietal lobe?
A
- structures: postcentral gyrus, posterior paracentral gyrus, superior and inferior parietal lobules
- functions: postcentral gyrus (primary somatosensory cortex, controls processing of tactile and proprioceptive info); inferior parietal lobule (one hemi, usually left; language comprehension); parietal cortex (aspects in spatial orientation and directing attention)
10
Q
- a somatotopic map that maps the contralateral half of each precentral (motor) and postcentral (sensory) gyri
- show how our bodies are represented within our brains
- spatially distorted and reflect the amount of innervation to a given body area
A
homunculus
11
Q
What are the structural features and general functions of the temporal lobe?
A
- structures: superior, middle, and inferior temporal gyri; inferior surface is made up of the broad occipitotemporal (fusiform) gyrus
- four functions: primary auditory cortex (superior surface of superior temporal gyrus); Wernicke’s area (comprehension of language*, posterior portion of superior temporal gyrus, usually on the left hemi); high-order processing of visual info; learning and memory
*comp of lang also presented in supramarginal and angular gyri (parietal lobe)*
12
Q
What are the structural features and general functions of the occipital lobe?
A
- structures: lateral occipital gyri (lateral surface), cuneus (wedge-shaped area btwn parietoccipital and calcarine sulci), primary visual cortex (contained in the walls of the calcarine sulcus, visual association center (remainder of the lobe, high order processing of visual info)
- functions: visual processing
13
Q
What are the structural features and general functions of the limbic lobe?
A
- structures: (not a true lobe, covers parts of the other 4 lobes) contains the cingulate gyrus and parahippocampal gyrus
- functions: processing of complex aspects of learning, memory, and emotion
14
Q
- lies buried in lateral sulcus, can be seen by prying open lateral sulcus
- can also remove opercula, which overlies this area and has parts in frontal, parietal, and temporal lobes
- circular sulcus outlines this area and marks its borders w/ the opercular areas of the cortex
- functions: variety of homeostatic functions related to basic survival needs, such as taste, visceral sensation, and autonomic control; controls autonomic functions through the regulation of the sympathetic and parasympathetic systems. It has a role in regulating the immune system
A
insular lobe
15
Q
- part of the brain that includes the thalamus, hypothalamus, epithalamus, and subthalamus (hemisections)
A
diencephalon
16
Q
- large mass of gray matter located in the dorsal part of the diencephalon
- nerve fibers project out of this area to the cerebral cortex in all directions, allowing hub-like exchanges of information
- gatekeeper for the cortex
A
thalamus
17
Q
- part of the diencephalon
- regulates hormonal, autonomic, and visceral functions
- links the nervous system to the endocrine system via the pituitary gland
A
hypothalamus
18
Q
- part of the diencephalon
- connects limbic system to other brain areas
- regulates circadian rhythms
A
epithalamus
19
Q
What is the function of association fibers, commissural fibers, and projection fibers within central white matter?
A
- association fibers: connect cortical areas within the same hemisphere
- commissural fibers: connect areas of the cortex in one hemisphere w/ that of the contralateral side:
corpus callosum (interconnects cerebral hemispheres, 250 mil axons),
anterior commissure (commissural fibers to/from temporal lobe, especially the inferior parts)
- projection fibers: carry info to/from the cerebral cortex (corona radiata
20
Q
- white matter bundle of fibers traveling to/from the cerebral cortex via the corona radiata
- fibers connect the thalamus with the cerebral cortex by thalamocortical and corticothalamic fibers
- divided into libs, each containing specific fibers: anterior limb, genu, posterior limb, sublenticular limb, retrolenticular limb
A
internal capsule
21
Q
- critical in the initiation and control of voluntary movement
- internal capsule contains most of the fibers interconnecting the cerebral cortex and deep structures (thalamus, _____ _____, and brainstem)
A
basal nuclei
22
Q
- plays major roles in cranial nerve function, conveys info to/from forebrain
- contains the midbrain, pons, and medulla
- together, they help to regulate breathing, heart rate, blood pressure, and several other important functions
A
brainstem
23
Q
- part of the brainstem
- houses the tectum (roof), superior and inferior colliculi (paired bumps posterior to cerebral aqueduct, and paired cerebral peduncles (make up most of this area)
- functions in vision, hearing, motor control, sleep and wakefulness, arousal (alertness), and temperature regulation
A
midbrain
24
Q
- part of the brainstem
- protruding basal area and tegmentum forms part of the floor of 4th ventricle
- contains neural pathways and tracts that conduct signals from the brain down to the cerebellum and medulla, and tracts that carry the sensory signals up into the thalamus
- contains cranial nerves involved in regulation of respiration, controls involuntary actions, sensory roles in hearing, equilibrium, and taste, and in facial sensations such as touch and pain, as well as motor roles in eye movement, facial expressions, chewing, swallowing, and the secretion of saliva and tears
- contains nuclei that relay signals from the forebrain to the cerebellum, along with nuclei that deal primarily with sleep, respiration, swallowing, bladder control, hearing, equilibrium, taste, eye movement, facial expressions, facial sensation, and posture
A
pons
25
Q
- part of the brainstem
- rostral open portion containing part of the 4th ventricle
- caudal closed portion, continuous w/ the SC
- functions in autonomic functions ranging from vomiting to sneezing
- contains the cardiac, respiratory, vomiting and vasomotor centers and therefore deals with the autonomic functions of breathing, heart rate and blood pressure as well as the sleep wake cycle
A
medulla
26
Q
- functions in sensory information processing and influences motor neurons
- damage can result in problems w/ equilibrium, postural control, and coordination
- surface consists of transverse ridges of gray matter, folia
- white matter is in the medullary center
A
cerebellum
27
Q
What is the path of spinal nerves from the spinal cord?
A
- posterior and anterior rootlets > posterior and anterior roots > spinal nerves
- posterior rootlets enter SC via posterolateral sulcus (shallow longitudinal groove)
- anterior rootlets leave SC via anterolateral sulcus (poorly defined)
28
Q
What are the constituents of the posterior horn of the SC?
A
- substantia gelatinosa: gray matter that caps posterior horn
- body: interneurons and projection neurons that transmit somatic and visceral sensory info
- Lissauer’s tract: white matter located btwn substantia gelatinosa and surface of SC
- Clark’s nucleus (posterior thoracic nucleus): cells located on medial surface of base of posterior horn (T1 to L2), prominent role in sensory processing and typically treated as part of posterior horn
29
Q
What are the constituents of the anterior horn of the SC?
A
- cell bodies of lower motor neurons supplying skeletal muscle
- influenced by different pathways to modulate movements
31
Q
What are the laminae of the SC?
A
- lamina I (marginal zone): thin gray matter covering substantia gelatinosa
- lamina II: substantia gelatinosa
- laminae III-VI: body of posterior horn
- lamina VII: intermediate gray matter including Clarke’s nucleus
- lamina VIII: interneurons of the anterior horn
- lamina IX: motor neurons of the anterior horn
- lamina X: gray matter surrounding central canal
40
Q
- relay a signal from primary afferents (in the periphery) to a target in the CNS
- can cross the midline of the body
*knowledge of crossover points is crucial in deciding where a lesion is*
A
second-order neurons
(in red)
41
Q
- relay the message to a final target in a specific cortical area
- cortex decides on given output
A
third-order neurons
(in blue)
43
Q
- ascending tract
- conveys ipsilateral proprioceptive, tactile, and vibratory info from the body (not face)
A
posterior column-medial lemniscus system (PCMLS)
44
Q
- ascending tract
- info relayed to cerebellum, thalamus, and motor cortex to influence efficiency of motor activity
A
spinocerebellar tracts
45
Q
- ascending tract
- relays pain, temp, and nondiscriminative touch from body (not face)
A
anterolateral system (ALS)
46
Q
- descending tract
- controls voluntary and fine movements of the musculature
A
corticospinal tract (CST)
47
Q
- descending tract
- influence motor neurons innervating primarily axial and neck musculature
A
vestibulospinal tract
48
Q
- descending tract
- excite flexor motor neurons and inhibit extensor motor neurons
A
rubrospinal fibers
