“I am a brain, Watson. The rest of me is a mere appendix “I am a brain, Watson. The rest of me is a mere appendix.” ― Arthur Conan Doyle, The Adventure of the Mazarin Stone

Neuroanatomy The Form of the Brain

Directional terms superior lateral medial posterior anterior inferior Thee are 3 common ways to slice the brain: coronal also called facial that slices in the plane of the eyes, sagittal along the midline, and horizontal which is parallel to the ground Anterior towards the front, posterior towards the back, inferior towards the ground, superior towards the top of the head, lateral towards the outside and medial towards the middle Figure from Purves, Neuroscience, 5th Ed. medial posterior anterior inferior

Protecting The Brain Skin Periosteum = leathery covering of cranial bones Cranium = bone w/fixed joints Meninges

Meninges Dura mater = tough fibrous tissue covering the brain. Contains blood vessels that nourish the brain. Holds in the cerebral-spinal fluid (CSF) Arachnoid Space Pia mater

Sub- v. Epidural Hematomas Epidural = Inflammation between dura and skull Subdural = between arachnoid space and dura

Cerebro-Spinal Fluid (CSF) CSF = plasma ultrafiltrate that bathes and protects the CNS. Produced by the choroid plexus (tissue in the lateral ventricles & 4th ventricle) Hydrocephalus = Inflammation resulting from obstruction of the aqueduct connecting the third & fourth ventricles

Major Regions of the Brain Cerebrum Cerebellum Spinal cord

Cerebral Cortex The outer layer of grey matter of the cerebrum Grey matter consists of soma (cell bodies)and unmyelinated axons White matter consists of myelinated axons Cerebral Cortex

Soma Axons We've looked at isolated single neurons so far. But this is a picture showing all the neurons in a single location in the brain. As I said before, there are 100 billion neurons throughout the brain. The scale of 100 billion is tough to imagine Let’s look inside to get a sense of how so many can be in such a small space

Cerebral Topography Gyri – Elevated ridges “winding” around the brain Cingulate Gyrus – Just above the corpus callossum Sulci – Small grooves dividing the gyri Central Sulcus – Divides the Frontal Lobe from the Parietal Lobe Fissures – Deep grooves, generally dividing large regions/lobes of the brain Longitudinal Fissure – Divides the two Cerebral Hemispheres Transverse Fissure – Separates the Cerebrum from the Cerebellum Sylvian/Lateral Fissure – Divides the Temporal Lobe from the Frontal and Parietal Lobes

Specific Sulci/Fissures: Central Sulcus Longitudinal Fissure Sylvian/Lateral Fissure Transverse Fissure http://www.bioon.com/book/biology/whole/image/1/1-8.tif.jpg http://www.dalbsoutss.eq.edu.au/Sheepbrains_Me/human_brain.gif

Cerebral Lobes Frontal Parietal Temporal Occipital

Frontal Lobe The frontal lobe is located deep to the frontal bone. Functions/actions: Memory formation Emotions Decision Making/Reasoning Personality Generally, the left side of the brain controls the right side of the body

Frontal Lobe – Cortical Regions Broca’s Area Orbitofrontal Cortex Primary Motor Cortex/ Precentral Gyrus Broca’s Area Orbitofrontal Cortex Olfactory Bulb Modified from: http://www.bioon.com/book/biology/whole/image/1/1-8.tif.jpg

Primary Motor Cortex Controls movements of the body Betz cells  alpha motor neurons (spinal cord)  muscle fibers The motor cortex contains a rough “map” of the body, with controls for the toes (top) to the mouth (bottom) in overlapping regions

Motor Homunculus Proportional model of organs to density of neural tissue devoted to said muscle/structure

Broca’s v. Wernicke’s Area BROCA =Located on the right frontal lobe Controls facial neurons, speech, and language comprehension WERNICKE = located on left temporal lobe Controls content of speech and language development

Orbitofrontal Cortex One of the least explored and understood regions of the cerebral cortex Located just above the orbits (eye sockets), in the frontal lobe Involved in adaptive learning and “personality” of an individual

Phineas Gage

Olfactory Bulb The most rostral (forward) part of the brain in most vertebrates, but is on the inferior side of the brain in humans Olfactory receptor neurons in the nasal cavity receive the smells, and transmit them to the brain

Parietal Lobe Where? The parietal lobe of the brain is located deep to the parietal bone of the skull What Functions? Sensory Integration Proprioception: aware- ness of body/body parts in space and in relation to each other)

Parietal Lobe – Cortical Regions Primary Somatosensory Cortex/ Postcentral Gyrus Somatosensory Association Cortex Primary Gustatory Cortex Modified from: http://www.bioon.com/book/biology/whole/image/1/1-8.tif.jpg

Somatosensory Cortex Processing of tactile, temperature, nociceptive (pain), and proprioceptive (spatial) information Neurons are also organized according to the type of sensation to which they respond (i.e. pressure, temperature, pain)

Somatosensory Homunculus This model shows what a man's body would look like if each part grew in proportion to the area of the cortex of the brain concerned with its sensory perception

Parietal Lobe – Other Cortical Regions Somatosensory Association Cortex Assists with integration/interpretation of sensations relative to body position and orientation in space (kinesthetic awareness) and hand-eye coordination Primary Gustatory Cortex Primary site of interpretation of gustation/taste

Occipital Lobe The occipital lobe is located deep to the occipital bone of the skull Functions: Processing, integration, interpretation of vision and visual stimuli

Occipital Lobe – Cortical Regions Primary Visual Cortex Visual Association Area Modified from: http://www.bioon.com/book/biology/whole/image/1/1-8.tif.jpg

Occipital Lobe – Cortical Regions Primary Visual Cortex Primary area of brain responsible for sight. Receives information via the optic nerve Visual Association Area Interprets information acquired through the primary visual cortex

Temporal Lobe The temporal lobes are located on the sides of the brain, deep to the temporal bones of the skull Functions: Hearing Organization/ comprehension of language Information retrieval (memory and memory retrieval)

Temporal Lobe- Cortical Regions Primary Auditory Cortex Wernike’s Area Primary Olfactory Cortex (Deep) Conducted from Olfactory Bulb Temporal Lobe- Cortical Regions Modified from: http://www.bioon.com/book/biology/whole/image/1/1-8.tif.jpg

Temporal Lobe – Cortical Regions Primary Auditory Cortex Responsible for hearing Primary Olfactory Cortex Interprets the sense of smell once it reaches the cortex via the olfactory bulbs Wernicke’s Area Located on the left temporal lobe Language comprehension

Cerebellum “Little brain”, located inferior to the cerebrum Functions: Motor control – doesn’t originate movement (i.e. primary motor cortex) but contributes to motor programs Attention & language (?) Regulating fear and pleasure responses (?) Composed of highly regularly arranged Purkinje cells (large neurons with many dendritic spines) and Granule cells (small neurons)

Brainstem The posterior region of the brain Continuous tissue with the spinal column All information relayed between the body and brain must pass through the brainstem

Segments of Brainstem The brainstem is composed of three segments: Medulla oblongata Pons Midbrain

Medulla Oblongata Lower half of the brainstem Contains autonomic centers re: Cardiac function Respiratory function Vomiting Vasomotor

Pons Relay action potentials from the forebrain to the cerebellum Deals primarily with: Sleep Respiration Swallowing Bladder control Hearing Posture Equilibrium Taste Eye movement Facial expressions Facial sensation

Midbrain Located superior to the pons Associated with: Vision Hearing Motor Control Sleep/awake Arousal (alertness) Temperature regulation

Limbic System Associated with higher order behaviors Hippocampus: corticosteroid production, spatial relations; long term memory Amygdala: reward, fear, mating, response to stress Limbic cortex: judgment, insight, motivation, mood, Fornix: relay signals from hippocampus to hypothalamus