Windows to the Brain: Introduction to Neuroanatomy

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Windows to the Brain: Introduction to Neuroanatomy Overview Planes of Section Radiographic Perspective Major Divisions Cortical Lobes, Gyri & Sulci General Functions Brodmann’s Areas Basal Forebrain Subcortical Structures Symptoms Cerebellum Structures Symptoms Katherine Taber, PhD, FANPA MIRECC Assistant Director - Education Research Health Scientist W.G. “Bill” Hefner VAMC, Salisbury NC Research Professor, Div Biomedical Sciences Edward Via College of Osteopathic Medicine Robin Hurley, MD, FANPA MIRECC Associate Director - Education ACOS/Research and Academic Affairs Service Line W.G. “Bill” Hefner VAMC, Salisbury NC Professor, Psychiatry and Radiology Wake Forest School of Medicine

revised September 2019 Source: http://www.mirecc.va.gov/visn6/Tools-Tips.asp

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1 Planes of Section

In medical practice the most Lateral View common way to view the brain is Superior the two dimensional sections r r o i provided by magnetic resonance o i r

r axial plane of section e e

imaging (MRI) and computed t t s n tomography (CT). While it is o A possible to image the brain in P virtually any orientation, the axial coronal plane of section plane of section is used most often as it allows the entire brain to be captured in the fewest number of sections. Anatomists Inferior prefer the coronal plane of section because many structures, Inferior (Bottom) View particularly small ones, are more easily recognized. Note that both r r o

the axial and sagittal planes of i o sagittal plane of section i r r section go from the front (anterior) e e t t s n to the back (posterior) of the brain. o A Axial goes from one side to the P Medial other (medial to lateral). Sagittal goes from top (superior) to bottom (inferior). coronal plane of section

Lateral

axial plane of section sagittal plane of section coronal plane of section

2 Radiographic Perspective

Clinical images are displayed in the radiographic perspective. Most teaching and reference materials use the anatomic perspective.

All radiographic images are displayed using a single set of conventions:

patient is lying on his/her back (supine) patient’s patient’s right left viewer is at patient’s feet looking toward the patient’s head

viewer There are 2 key differences between the radiographic perspective and the anatomic perspective that are important to remember when viewing clinical brain images.

[1] The left side of an axial or coronal brain image is the right side of the brain: R L R L patient’s patient’s right left

viewer

[2] On axial images brainstem and spinal cord will be inverted compared to how they are displayed in most teaching and reference materials:

3 Major Divisions Major Divisions The neural tube (illustrated in schematic form) expands locally to form the 3 primary divisions or vesicles: forebrain (prosencephalon, yellow), midbrain (mesencephalon, green), and hindbrain (rhombencephalon, purple). These in turn form the 5 secondary divisions. The forebrain vesicle subdivides into telencephalon (yellow) and diencephalon (light green). The hindbrain vesicle subdivides into the metencephalon (blue) and myelencephalon (pink). * Primary Secondary Final Areas Formed Divisions Divisions

forebrain telencephalon cerebral hemispheres, limbic system, (prosencephalon) basal ganglia diencephalon thalamus, hypothalamus, epithalamus, midbrain subthalamus, optic vesicle (mesencephalon)

mesencephalon superior & inferior colliculi, red nucleus, hindbrain substantia nigra, periaqueductal gray (rhombencephalon) metencephalon pons, cerebellum

myelencephalon medulla

spinal cord spinal cord z Inferior (Bottom) View The 5 secondary divisions are color-coded onto magnetic resonance images to provide cerebral cortex overall orientation. pons medulla cerebellum

Midline Medial (Parasagittal) View Lateral View

cerebral cortex cerebral cortex corpus callosum diencephalon

midbrain pons cerebellum pons cerebellum medulla medulla *Taber KH, Salpekar J, Wong AHC, Hurley RA. J Neuropsychiatry Clin Neurosci 2011;23(1): 1-5.

4 Cerebral Cortex - Lobes Midline Medial (Parasagittal) View Lateral View

parietal frontal parietal limbic frontal occipital occipital temporal

parietal frontal limbic parietal frontal

occipital occipital

temporal temporal Medial Orbital

Inferior (Bottom) View The highly in-folded cerebral cortex is the largest single division of the temporal human brain. Anatomists commonly occipital divide it into four sections or lobes - frontal the frontal, temporal, parietal and limbic occipital lobes. Some consider the limbic areas of cortex to comprise a fifth lobe, whereas others include these areas in the frontal and temporal lobes and diencephalon. Note that the medial and posterior inferior surfaces of the temporal lobe Lateral can only be seen on the drawings of temporal the medial and inferior surfaces of the brain. This is because the brainstem frontal occipital and cerebellum have been omitted on limbic the drawings. Medial parietal

Major Gyri & Sulci Midline Medial (Parasagittal) View Lateral View Central Central (Rolandic) Sulcus l (Rolandic) a r l Sulcus t a n tr S Paracentral P Parietooccipital al e u re nt c n p lobule cu Sulcus o l e e P e n r ta r tc a ri l e F n P s r o nta us r o L ie r ro o r o ob ta F ri F P u l r Cingulate e e A le io Calcarine l r p d ma n u r ra r g e Sulcus id o p g u S l u i

p Cuneus i n r S l

u M ta Subcentral a a

e l r S f n al n o r I r po Lin F em l Occipital gua r T ra l rio po pe m l Su Te ra Gyrus Rectus Orbital dle po id Tem M or eri Inf SylvOiarnbiFtiasslure (Lateral Sulcus) Central Central (Rolandic) Sulcus (Rolandic) Sulcus l Paracentral l a l tal ta r P S on lobule Pr Parietooccipital n t ra a up r ec ro n t ri e F u Sulcus F l e n et r r ne r ta c e a io io Cingulate u o n e c A l r r s i ro r t ng Lo e r F P s u b e o la u p p le P r le u Calcarine u ma Subcallosal d r ra r S S d p g

Cuneus Sulcus o u i i l n

(Paraolfactory) i S

r a a

t l Area M e Hippocampus f n Subcentral l Occipital In o ra al r po Uncus p Lin F m am gu r Te l poc al rio ora arahip pe p Gyrus Rectus P m Su Tem usifor l le ral F ora dd mpo mp Mi r Te Inferior Te Sylvian Fissure ferio (Lateral Sulcus) In frontal temporal parietal occipital limbic Inferior (Bottom) View

Posterior Orbital ral al po Later Tem bital rior Or Infe Anterior form An outfolding of the cerebral Orbital Fusi Medial Orbital cortex is called a gyrus Parahippocampal Gyrus Rectus (plural is gyri), an infolding is Uncus called a sulcus (plural is sulci). Some very large sulci are called fissures. Although major gyri and sulci are present in all normal brains, Sylvian Fissure they can vary considerably in (Lateral Sulcus) Inf erior both extent and location. Temp al Fu ora Lateral Later sifo l tal rm Many areas have Orbi considerable normal AnteriorPosterior rahippo Orbital Orbital Pa cam pa variation in the folding Medial Orbital Uncus l patterns. Gyrus Rectus Medial

7 Major Functions Right Hemisphere Medial (Parasagittal) View Lateral View Somatosensory Motor Initiation Motor Hip & Synchronization Sensory Somatosensory Initiation of Speech Integration & Arm & Synchronization Leg & Complex Focused Attention, Recognition Hand of Speech Movements N onverbal Intellect & Complex Sensory Integration & Foot & N onverbal Hand Movements Memory Recognition Audiovisual Focused Attention, Management Awareness & Face Deficit Recognition N onverbal Intellect Visual Face & N onverbal Orientation, Music & Voice Tongue Speech Memory Recognition Prosody & Guidance & Hearing Management Scanning Gesturing Visuospacial Smell Social Conduct, Recognition Visuospacial Insight & Seeing N aming Recognition Judgment N aming Visual Orientation, Social Conduct, Seeing, Color Vision, Guidance & Scanning Insight & Judgment & W hole Object Imaging Inferior (Bottom) View

Right Hemisphere - In most Retrograde Lateral N am individuals, the processing of Visuospacial Episodic ing nonverbal information, such as Recognition Memory N onverbal Social Seeing, Conduct, music or visuospatial information, Color Vision, Memory & Emotion Insight & occurs primarily in the right & Smell W hole Object Judgment hemisphere. Imaging frontal temporal parietal occipital limbic Medial Left Hemisphere Medial (Parasagittal) View Lateral View Motor Somatosensory Motor Hip Focused Initiation & Somatosensory Initiation & Attention, Synchronization Synchronization Arm of Speech Leg of Speech Sensory Integration Verbal Intellect Leg Hand & Verbal & Complex & Complex & Recognition S Foot m Movement Foot Sensory Integration V o Movement Memory P i o Hand g u su t Hand in r a h d & Recognition su l n Management i Hand W riting To t sta Focused er Dictation Face Face d Attention, Un Reading Aloud Verbal Verbal Intellect Face Face Repetition Spelling Visual Speech & Verbal Speaking Tongue Orientation, Memory Hearing Guidance & Management Scanning Visual Recognition Social Conduct, Smell Visual N aming Insight & Seeing Judgment Recognition Social Conduct, Visual Orientation, N aming Seeing, Color Vision & Insight & Guidance & Scanning W hole Object Imaging Judgment Inferior (Bottom) View Lateral Left Hemisphere - In most N aming Visuospacial individuals, the processing of Recognition verbal information, including Social Verbal Memory Conduct, & Emotion Seeing, language, occurs primarily in the Insight & Color Vision Judgment Smell & left hemisphere. W hole Object Imaging frontal temporal parietal occipital limbic Medial 8 Brodmann’s Areas In the early part of the 20th century, Brodmann defined cortical areas based upon features such as the size, shape and distribution of neurons (cytoarchitecture). An approximation of these areas are provided in the illustrations below. Versions of this system are still widely used. While useful, it is important to always keep in mind that Brodmann’s work was based upon analysis of a single brain. Brains vary greatly in size, shape, and infolding patterns. Research has shown that there is a wide range in the extent of a specific Brodmann area when compared across individuals. Thus, such maps should be used only as extremely general guides. Lateral View 4 3 1 6 4 4 4 4 2 limbic temporal occipital parietal frontal 6 5 5 6 4 4 4 4 3 1 7 6 6 6 4 2 5 5 6 6 4 4 7 7 6 6 6 6 4 4 3 1 5 7 6 6 6 6 4 4 4 4 5 7 7 6 6 6 4 31 2 5 7 7 7 8 8 8 8 6 4 4 4 5 7 7 8 6 6 4 7 7 7 7 8 8 8 8 6 6 4 4 3 12 7 7 7 7 8 8 8 8 8 6 6 40 7 7 7 7 9 9 9 8 8 6 4 4 12 7 7 9 8 6 6 4 40 40 7 7 19 9 9 9 9 8 6 6 4 3 7 7 19 9 9 9 8 6 3 1 40 7 19 9 9 9 9 8 6 4 2 40 40 40 7 9 9 9 9 8 8 6 6 3 39 7 19 19 9 9 9 9 4 1 1 2 40 39 19 9 9 9 9 8 6 6 40 40 40 19 9 9 9 9 9 8 6 3 1 1 39 19 19 46 9 9 6 4 2 40 19 19 10 10 10 46 9 9 6 6 3 40 40 40 39 39 19 19 46 9 6 4 1 1 40 39 19 10 10 10 46 46 9 9 9 9 6 2 40 39 19 19 19 18 45 6 4 1 1 40 40 22 39 10 46 46 46 44 44 3 40 22 39 1919 19 18 10 10 45 6 22 39 18 46 46 46 45 44 6 4 1 2 40 40 21 39 19 10 45 44 6 3 40 40 22 37 19 18 18 10 10 46 46 45 45 4 1 2 40 22 37 39 17 46 44 6 52 42 22 21 37 19 18 10 45 45 44 6 4 3 4352 52 41 22 37 19 18 1717 10 46 46 45 44 43 41 41 41 42 21 10 45 45 44 6 42 42 42 22 37 19 18 10 10 46 45 45 45 22 37 19 18 1717 45 45 44 22 22 22 22 22 22 21 19 19 10 45 45 22 22 22 37 19 18 10 10 45 45 44 38 22 22 22 21 19 18 17 10 45 22 22 21 19 19 18 10 47 45 45 45 45 38 22 22 21 37 19 19 10 47 45 45 38 38 21 21 2121 37 19 11 11 47 38 38 21 21 21 19 19 19 11 11 47 45 38 38 21 21 37 37 11 47 47 21 21 37 37 19 11 11 11 11 38 38 21 21 21 37 11 11 38 21 21 21 21 37 38 21 21 20 38 21 21 21 21 21 20 38 38 21 20 38 21 20 20 38 38 20 20 20 38 20 20 20 20 Medial (Parasagittal) View 4 4 4 6 6 4 4 4 4 3 frontal temporal parietal occipital limbic 6 4 4 1 6 6 4 4 3 1 2 6 6 6 4 4 4 1 5 5 6 6 4 4 2 7 6 6 6 6 4 4 311 5 5 6 6 6 4 4 4 5 7 8 6 6 6 4 4 4 3 12 7 7 6 6 6 4 4 4 1 5 5 7 8 8 6 6 6 4 4 4 5 7 7 7 8 8 6 6 6 4 12 5 7 7 8 8 6 6 6 6 6 4 4 4 4 3 5 7 7 7 8 6 5 5 7 7 7 9 8 8 8 8 6 6 6 4 4 7 7 7 7 7 8 8 6 4 4 5 5 5 31 7 9 9 32 6 6 4 4 31 7 7 7 7 7 9 32 32 32 6 4 4 5 31 7 9 9 32 6 4 5 31 31 31 7 9 32 32 32 32 32 24 4 4 4 31 7 7 7 19 9 9 32 32 24 31 31 31 31 9 9 32 24 31 31 31 31 31 19 9 32 24 24 24 24 31 31 31 19 19 9 9 32 32 24 24 23 23 23 31 31 31 18 19 9 9 32 24 23 23 23 31 9 9 32 24 23 23 23 31 31 18 1919 9 32 24 33 23 23 23 31 18 18 9 9 32 24 33 23 31 18 9 32 293023 18 18 18 18 9 32 30 23 18 9 9 32 2433 2629 18 18 18 18 32 3023 18 18 17 10 9 32 33 29 18 10 32 263023 17 17 17 17 32 32 24 17 17 10 33 2923 17 17 17 32 32 32 2930 17 17 10 32 24 33 25 2630 18 17 17 10 32 24 34 19 18 17 10 32 25 34 34 27 30 35 18 17 17 17 10 10 10 32 27 35 19 19 18 10 10 25 3836 34 34 27 27 37 19 18 18 12 12 12 12 34 27 27 28 35 19 10 10 12 12 25 36 28 28 27 28 35 37 19 19 1919 18 12 12 12 38 28 28 28 35 35 37 12 12 12 25 36 28 28 28 35 37 19 19 19 12 11 11 38 28 36 35 37 19 11 11 11 11 28 28 36 36 35 37 37 37 36 36 37 37 19 38 36 36 36 20 37 37 38 38 36 20 37 36 36 20 37 38 20 20 20 38 20 20 20 20 20 20 20 20 9 Basal Forebrain The basal forebrain area contains many cholinergic neurons in the basal nucleus of Meynert, nucleus of the diagonal band and septal nuclei. The general location of this important region Sagittal Brain Section and its projections to cortex are approximated on sagittal and coronal magnetic resonance images. The basal forebrain cholinergic neurons project to cortex via both medial and lateral routes. Fibers travel to hippocampus via the fornix, olfactory cortex via the olfactory tract and amydala via stria terminalis and the ventral amygdalofugal pathway. basal forebrain region Coronal Brain Sections septal nuclei lateral pathways lateral pathways

medial pathway amygdala nucleus diagonal band basal nucleus

Major Subcortical Structures A brief guide to neuropsychiatric symptoms associated with injury to each of the major subcortical structures is color-coded to match the illustration on the previous page.

Thalamus - (left) deficits in language, verbal intellect, and verbal memory (right) deficits in visuospatial and nonverbal intellect and visual memory, (bilateral) severe memory impairment (“thalamic amnesia”) as well as dementia; damage to the anterior and medial thalamus can also result in disturbances of autonomic functions, mood, and the sleep/waking cycle.

Caudate - apathy, disinhibition, disorganization, executive dysfunction, depression, memory loss, atypical aphasia, psychosis, personality changes, and predisposition for delirium.

Putamen - most commonly language and behavioral deficits (i.e., atypical aphasia, obsessive - compulsive traits, executive dysfunction); hemineglect, depression, and memory loss have also been reported.

Globus pallidus - anxiety, depression, apathy, psychosis, and central pain; less often reported symptoms include amnesia and cognitive deficits.

Amygdala - passivity or aggression, hypersexuality, hyperorality, hyperphagia, decreased fear, anxiety or startle, and decreased link between emotion and memory.

Hippocampal formation - primarily memory deficits including anterograde and retrograde amnesia, inability to form new memories, and temporally graded amnesia.

Fornix - memory deficits include impaired recent memory, syndrome of transitory amnesia, and long-term anterograde amnesia.

Hypothalamus - aggression, violence, anorexia, depression, impaired short-term memory, dementia, gelastic seizures, and altered sleep/wake cycle.

Mammillary body - memory deficits and psychosis.

Substantia nigra - primarily behavioral and emotional deficits (i.e., apraxia, ataxia, aggression, and depression), with less frequent reports of memory and cognitive deficits.