Exam 2: Neuroanatomy Part 2, deck 1 Flashcards
Cerebral Hemispheres
Cerebrum consists of 2 cerebral hemispheres, roughly equal halves of brain. Cortex refers to the outer surface of the brain; contains 2 basic cell types: Pyramidal cells and Nonpyramidal cells
6 Layers of Cerebrum
Outmost layer=glial cells and axons
2nd and 3rd layer=pyramidal cells
4th layer= nonpyramidal cells
5th and 6th layer=pyramidal cells
Nonpyramidal cells
involved in sensory function
(connect to more local regions)
Pyramidal cells
involved in motor function (project to
more distant regions)
Landmarks of cerebrum
Cerebral longitudinal fissure, gyrus, sulcus, lateral sulcus, central sulcus. Divided into 5 lobes frontal, parietal, occipital, temporal, insular.
Cerebral longitudinal fissure
separates left and
right cerebral hemispheres
Gyrus
a ridge on the cerebral cortex
Sulcus
infolding valleys that separate gyri
◦ if the groove is deeper or more pronounced it is termed a fissure
Lateral Sulcus (Sylvian Fissure)
divides temporal from frontal & anterior parietal
Central Sulcus (Rolandic Sulcus)
separates frontal and parietal entirely
Frontal Lobe
Largest of the lobes
Predominates in planning, initiation, and
inhibition of voluntary motion, as well as
cognitive function
Key areas: Broca’s Area and Motor Strip
Broca’s Area
speech motor planning in
dominant hemisphere
Motor Strip (a.k.a. pre-central gyrus)
site of initiation of voluntary motor movement
Parietal Lobe
Primary reception sight for body (somatic) sense, all senses that reach consciousness terminate within parietal lobe, integrates info related to vision, audition, and
somatic sense.
Key Areas: Postcentral gyrus, Supramarginal gyri, Angular gyri
Supramarginal gyri
some involvement in motor planning
for speech
Postcentral gyrus
sensory counterpart to the motor strip,
primary site of sensory output; receives sensation from various parts of body
Angular gyri
important in comprehension of written material
Temporal Lobe
Site of auditory reception and is very
important for auditory and receptive
language processing
Key areas: Superior temporal gyrus, Heschl’s Gyrus, Wernicke’s area.
Superior temporal gyrus
Runs Heschl’s Gyrus, posterior portion of Wernicke’s area.
Heschl’s Gyrus
Where all auditory information is projected
Wernicke’s area
Important for language decoding.
Occipital Lobe
Posterior limit of brain, responsible for receiving visual stimulation, as well as some of the higher-level visual processing. Related to visual agnosia; Prosopagnosia: inability to recognize faces.
Insula (Island of Reil)
Located deep to a region of cerebrum
known as the operculum, believed to be involved in consciousness and play a role in emotion and the regulation of the body’s homeostasis. Associated with arcuate fasciculus (conduction aphasia)
Limbic System
Not an anatomically distinct region but is composed of:
◦ Uncus (formed by amygdala)
◦ Thalamus
◦ Parahippocampal gyrus
◦ Cingulate gyrus
◦ Olfactory bulb and tract
◦ Hippocampus
◦ Dentate gyrus
Related to functional relationships to:
◦ Motivation
◦ Sex drive
◦ Emotional behavior
◦ Affect
Myelinated Fibers
Gray matter of the cortex is predominately made up of neuron bodies, whereas white matter represents myelinated axon fibers
These fibers make up the communication link between neurons (without them there would be no neural function)
Three types of fibers: Projection fibers, association fibers, commissural fibers.
Projection Fibers
connects cortex with distant locations
Association Fibers
provides communication between regions of
the same hemisphere
Commissural Fibers
runs from one location on a hemisphere to
the corresponding location on the opposite hemisphere (mainly the corpus callosum)
Anatomy of the Subcortex: Basal Ganglia
Group of large nuclei that partially surround
the thalamus, important in the control of movement; regulates voluntary motor activities; functions in starting, stopping, and monitoring arm swinging and gait
Made up of:
◦ Caudate nucleus
◦ Putamen
◦ Globus Pallidus
Anatomy of the Subcortex: Hippocampus
- Involved in memory forming, organizing, and storing
- As a limbic system structure, it is important in forming new memories and connecting emotions and senses, such as smell and sound, to memories
- Sends memories out to appropriate cerebral hemisphere for long-term storage and retrieval
- Also appears to be specialized to recognize
faces of individuals
Anatomy of the Subcortex: Diencephalon
Structures of the Diencephalon:
◦ Thalamus
◦ Hypothalamus
◦ Epithalamus
◦ Subthalamus
Function:
◦ Relays sensory information between brain regions
◦ Controls many autonomic functions of the PNS
◦ Connects structures of the endocrine system with the nervous system
◦ Works in conjunction with the limbic system to generate and manage emotions and memories
Specific Functions of Diencephalon
- Directing sense impulses throughout the body
- Autonomic function control
- Endocrine function control
- Motor function control
- Homeostasis
- Hearing, vision, taste
- Touch perception
Thalamus
- Large, dual-lobed mass of grey matter
- Involved in sensory perception and
regulation of motor functions - As a limbic system structure, it connects
areas of the cortex involved in perception
and movement with related parts of the
brain and spinal cord - As a regulator of sensory information, it
controls sleep and awake states of
consciousness
-Dejerine-roussy or thalamic pain (excessive pain, hypersensitive to stimuli)
Hypothalamus
- Control center for many autonomic
functions of PNS - Connections with structures of endocrine
and nervous systems enable maintenance
of homeostasis
-Blood vessel connection between hypothalamus
and pituitary gland
-Allows for control of pituitary hormone secretion - As a limbic system structure, influences
emotional responses
Epithalamus
Secretion of melatonin by the
pineal gland (involved in circadian
rhythms), and regulation of motor pathways
and emotions
Subthalamus
Involved in the control of striated muscle.
Circle of Willis
Blood supply to the brain. The arrangement of the brain’s arteries into the Circle of Willis creates redundancies to ensure constant blood supply to the brain. If one part of the circle or one of the arteries supplying the circle is blocked or narrowed, blood flow from the other blood vessels can often preserve the cerebral perfusion.
**Left middle cerebral artery: language deficits and motor deficits.
Venous Drainage & Blockage
System of blood vessels called veins that
provide the means of draining carbon
dioxide-laden blood to the lungs from
reoxygenation.
Obstruction in cerebrovascular supply typically occurs as:
◦ Thrombus: a foreign body (blood clot) that obstructs blood vessel
◦ Embolism: when a thrombus breaks loose from its site of formation and floats through bloodstream and causes occlusion
Anatomy of the Brainstem
Medulla, Pons, Midbrain
Cranial Nerves and their nuclei arise from
the brainstem and basic bodily functions
of life are maintained here
Medulla oblongata
A portion of the hindbrain that controls
autonomic functions
- Digestion
- Heart and blood vessel function
- Swallowing
- Sneezing
◦ Motor and sensory neurons from midbrain and forebrain
◦ Relay of nerve signals between the brain and spinal cord
◦ Coordination of body movements
Pons
Description:
◦ Connects the cerebral cortex with the medulla oblongata
◦ Communication and coordination center between the two cerebral hemispheres
◦ Helps in transferring of messages between brain and spinal cord
Function:
◦ Arousal
◦ Controlling autonomic functions
◦ Relaying sensory information between cerebrum and cerebellum
◦ Sleep
Midbrain
- Midbrain and hindbrain make up the
brainstem - Connects the hindbrain and the forebrain
- Involved in auditory and visual responses as well as motor function
Reticular Formation (also called Reticular Activating System)
Function:
◦ Arousal
◦ Attention
◦ Cardiac Reflexes
◦ Motor Functions
◦ Regulates Awareness
◦ Relays nerve signals to the cerebral cortex
◦ Sleep
Location:
◦ The reticular formation is a group of nerve fibers located inside the brainstem (spans the medulla, pons and midbrain)
Anatomy of the Spinal Cord
- Spinal cord if the information lifeline to and from the periphery of the body
- Made up of a long mass of neurons, with both cell bodies and projections from (and to) those neurons
- Gray portions are neuron cell bodies and white portions are the myelinated fibers of tracts that communicate info to and from brain
- Efferent (motor) tracts
- Afferent (sensory) tracts
Efferent (motor) tracts
such as corticospinal tract, transmit information from brain to spinal nerves.
Afferent (sensory) tracts
such as spinothalamic tract, transmit
info concerning the physical state of limbs and trunk to higher brain centers
More anatomy of spinal cord
- Begins at foramen magnum of skull and courses through the vertebral canal
- Safely protected by long tube made up of
connective tissue (the meningeal linings) - 31 pairs of spinal nerves arise from regions
related to the vertebra:
◦ 8 pairs of cervical spinal nerves
◦ 12 pairs of thoracic nerves
◦ 5 pairs of lumbar and sacral nerves
◦ 1 pair of coccygeal nerves
Cerebellum
- Responsible for coordinating motor
commands with sensory inputs to
control movement - Communicates with brainstem, spinal cord,
and cerebral cortex by means of superior,
middle and inferior peduncles - Also plays significant role as memory for
motor functions and even cognitive
processing - Composed of 2 hemispheres (the vermis
separates the two lobes)
Functions of Cerebellum
Motor:
◦ Helps in planning, monitoring, and correction of motor movement using sensory feedback
◦ Coordinates fine motor activity
Linguistic:
◦ Perception of speech/language, verbal working memory, verbal fluency, grammar processing, writing, and reading
Testing the Cerebellum
- Finger to nose test
- Diadochokinesis test (pᴧ-tᴧ-kᴧ)
- Uncoordinated, sloppy movement may indicate cerebellar damage
Cerebellar Damage Symptoms + Disorders
Symptoms: Ataxia, Dysmetria, Dysdiadochokinesia, Nystagmus, Ataxic dysarthria, hypotonia.
Disorders: Cerebellar hemispheric syndrome, Friedreich ataxia.
Brodmann Map
- Developed by Korbinian Brodmann (1868–1918)
- Divides brain into 52
areas based on:
◦ Brain’s gross anatomy
◦ Cellular structure of brain - Areas called Brodmann areas (BA)
Frontal Lobe: Prefrontal Cortex
- Occupies BA 9, 10, 11, 12, 45, 46, 47
- Functionally involved
with cognition (executive control),
personality, decision making, and social
behavior
Functional Regions of PFC
- Dorsolateral prefrontal cortex (BA 9, 10, 46)
- Ventrolateral prefrontal cortex (BA 45,47)
- Orbitofrontal prefrontal cortex (BA 11, 12)
- Medial Prefrontal Cortex (BA 24, 25, 32)
Prefrontal Cortex Damage
Profile 1 (Depressive): Apathetic, Abulia, Akinesia, Perseveration, Mutism, Depression, Hyposexuality.
Profile 2 (Manic): Explosive emotional lability, environmental dependency, distractibility, impersistence, confabulation, hypersexuality.
Frontal Lobe: Frontal Eye Fields
- Occupies BA 8
- Controls eye movements (up,
down, left, and right) - Damage results in eyes deviating
toward the side of injury - Involved in uncertainty and
hope - Sometimes included as part of
prefrontal cortex
Frontal Lobe: Broca’s Area
- Occupies BA 44 and 45
- Found on third frontal
convolution (i.e., inferior frontal
gyrus) - Area 45 is known as pars
triangularis, involved in interpretation of language (syntax) and planning/programming of verbal responses - Area 44 is known as pars opercularis, involved in coordination of speech organs for language production
- Paul Broca, through observations of Tan, one of first to associate BA 44, 45 with speech production
- Impairment to this area may lead to Broca’s aphasia
Frontal Lobe: Premotor Cortex
- Occupies BA 6
- Close relationship to BA 44
- Involved in selecting and
planning of motor movements - Supplementary motor area
(SMA) located at top of BA 6
and is involved in sequencing
and “turning on” motor plans
Types of Apraxia
- Ideational apraxia
- Ideomotor apraxia
- Limb-kinetic apraxia
- Constructional apraxia
- Gait apraxia
- Dressing apraxia
- Oculomotor apraxia
- Oral/buccofacial apraxia
- Apraxia of speech
Frontal Lobe: Primary Motor Cortex
- Occupies BA 4
- Sends motor plans developed in BA 6 to
the muscles for them to act (e.g., speech
muscles) - BA 4 has been mapped to form a homunculus or “little man
Parietal Lobe: Primary Sensory Cortex
- Occupies BA 1, 2, and 3
- Processes somatosensory information such as:
◦ Vibration
◦ Proprioception
◦ Touch
◦ Stereognosis - Homunculus present
Parietal Lobe: Somatosensory Association
Cortex
- Occupies BA 5 and 7
- Interprets sensory experience during motor movements
- This sensory experience is used to refine motor action
- Involved in the fine movements associated with speech
- Plays role in writing sensory and motor experience
Parietal Lobe: Angular Gyrus
- Occupies BA 39
- Involved in reading and math abilities
- Damage can lead to alexia and acalculia
- May also be involved in understanding metaphors and our sense of embodiment
- Damage can lead to outer body experiences (OBEs)
- Damage can also lead to Gerstmann syndrome
Parietal Lobe: Supramarginal Gyrus
- Occupies BA 40
- Closely related to the angular gyrus (BA 39)
- Involved in phonological system; stores auditory representations of phonemes (auditory images)
Occipital Lobe: Visual Cortex
- Occupies BA 17, 18, and 19
- Where information from eyes is received
and processed - Two streams of vision:
◦ Dorsal stream (18, 19, 7, and 39?): the where of vision; analyzes motion and spatial relationships
◦ Ventral stream (18, 19, and 37): the what of vision; analyzes forms, colors, and faces
Temporal Lobe: Inferior Temporal Area
- Occupies BA 20 and 21
- Involved in processing of auditory and
language information as well as reading facial emotions - May play a role in hallucinations
Temporal Lobe: Parahippocampal Gyrus
- Occupies BA 27, 28, 34, 35, and 36
- Located on medial surface of temporal lobe
Temporal Lobe: Fusiform Gyrus
- Occupies BA 37
- Also known as occipitotemporal gyrus
- Important in remembering and
naming seen objects - Visual agnosia, auditory agnosia, tactile agnosia
Temporal Lobe: Temporal Pole
- Occupies BA 38
Temporal Lobe: Primary Auditory Cortex
- Occupies BA 41 and 42 (42 is the secondary auditory cortex, but 41/42 usually discussed as a unit called the primary auditory cortex)
- Also known as Heschl’s gyrus
Temporal Lobe: Wernicke’s Area
- Occupies BA 22
- Named after Karl Wernicke
- Involved in attaching meaning to auditory information
Cingulate Cortex
- Name means “band that encircles”
- Occupies BA 23–26, 30–33
- Sandwiched between corpus callosum and frontal and parietal lobes
- Is part of the limbic system and has connections to the prefrontal cortex and hippocampus
Functionally, involved in the following:
◦ Anterior parts: cognitive control, detecting
errors, detecting conflicts, and problem solving
◦ Posterior parts: autobiographical memory,
managing risky behavior, and emotional
processing
