“i am a brain, watson. the rest of me is a mere appendix.” ― arthur conan doyle, the adventure...

“I am a brain, Watson. The rest of me is a mere appendix.”

― Arthur Conan Doyle, The Adventure of the Mazarin Stone

NEUROANATOMYThe Form of the Brain

Directional terms

posteriormedial

lateral

superior

inferioranterior

• Skin• Periosteum = leathery covering of cranial bones

• Cranium = bone w/fixed joints

• Meninges

Protecting The Brain

• 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

Meninges

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

Axons

Soma

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

Longitudinal Fissure

Transverse Fissure

Sylvian/Lateral Fissure

Central Sulcus

http://www.bioon.com/book/biology/whole/image/1/1-8.tif.jpg http://www.dalbsoutss.eq.edu.au/Sheepbrains_Me/human_brain.gif

Specific Sulci/Fissures:

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

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

Frontal Lobe – Cortical Regions

• 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

Primary Motor Cortex

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)

Primary Somatosensory Cortex/ Postcentral Gyrus

Primary Gustatory Cortex

Somatosensory Association Cortex

Modified from: http://www.bioon.com/book/biology/whole/image/1/1-8.tif.jpg

Parietal Lobe – Cortical Regions

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

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

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)

Primary Auditory Cortex

Wernike’s Area

Primary Olfactory Cortex (Deep)Conducted from Olfactory Bulb

Modified from: http://www.bioon.com/book/biology/whole/image/1/1-8.tif.jpg

Temporal Lobe-

Cortical Regions

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