Brain + Cranial Nerves
Central Canal
- 10% of which CSF travels through - Runs through entire spinal cord
Premotor Cortex
- Anterior to precentral gyrus - Plans motor movement - Sends information to precentral gyrus
Subarachnoid Space
- Between the arachnoid + pia mater - A true space - CSF flows through
Cranial Subdural Space
- Between the cranial dura + arachnoid mater - Has the potential to be filled with fluid when necessary - Does not normally exist
Mandibular Branch
- Both sensory + motor function - Passes through foramen ovale - Innervates muscles of mastication - Sensation on lower teeth
Six Major Regions of the Brain
- Cerebrum - Diencephalon - Cerebellum - Mesencephalon - Pons - Medulla
Diencephalon
- Completely inside of the cerebrum - Divided into three regions: > Epithalamus > Thalamus > Hypothalamus
Hypothalamus Examples
- Controls thirst that gives us desire to drink - Increases or decreases heart rate
Nutrients Going into BBB Examples
- Glucose - O2
Third Ventricle
- Is in-between the right + left sides of the thalamus - Fluid filled space - Interthalamic adhesion is needed to have the two thalami surrounding the third ventricle
Abducens Nerve (VI)
- Motor function - Involved with abducting the eyeball - Moves eyes laterally towards the outside - Innervates lateral rectus muscle
Trigeminal Nerve (V) Branches
- Ophthalmic branch - Maxillary branch - Mandibular branch
Frontal Lobes Components
- Precentral gyrus - Premotor cortex - Prefrontal cortex
Occipital Lobe
- Related to vision - Related to perception of visual stimuli - Includes: > Visual cortex > Visual association area
Cranial Arachnoid Mater
- Resembles a spider web due to arachnoid trabeculae - Encloses and protects blood vessels that supplies the brain
Optic Nerves (II)
- Sensory function ---> carries visual information to the specific part of the brain - Paired - Only pair that comes together + cross + split again - Passes through optic canal of sphenoid bone > Allows us our visual sensory info. from each eye to be received on both sides of the brain simultaneously
Cranial Subdural Space Example
- Subdural hematoma - This is the space that gets filled with blood
Brainstem
- Three main areas: > Mesencephalon > Pons > Medulla oblongata
Arbor Vitae
- White matter - Looks like the tree of life
Arachnoid Villi
- Works as a one way valve - When CSF pressure is less than venous pressure, arachnoid villi will not let blood pass into ventricular system and vice versa
Cerebellum Example
Being able to dance, ride a bike, etc.
Visual Association Area
Being able to recognize a face
Frontal + Parietal Lobes
Has central sulcus in-between them
Parietal + Occipital Lobes
Has parieto-occipital sulcus in-between them
Epithalamus
Has the pineal gland
Vermis
Separates right + left hemisphere of the cerebellum
Premotor Cortex Example
Thinking about picking up a pen
Purkinje Layer of Purkinje Cells
- Aka intermediate layer - Where purkinje cell bodies are found - Middle layer
Mesencephalon
- Aka midbrain - Located in the middle of the two brain regions (diencephalon/cerebrum + pons/ medulla oblongata) - Has a role in moving our eyes > Extrinsic eye muscles are innervated by nerves coming out of the mesencephalon - Processes sight, sound, and associative reflex
Precentral Gyrus
- Aka primary motor cortex - Anterior to the central sulcus - Sends nerve impulses towards the muscles (initiation of movement) - Has pyramidal cells
Post-Central Gyrus
- Aka primary somatosensory cortex - Posterior to central sulcus - Where sensations are consciously felt
Molecular Layer of Purkinje Cells
- Aka synaptic layer - Where the dendrites are found - Outer layer
Prefrontal Cortex
- Anterior to premotor cortex - Area for: > Thinking > Problem solving > Concentration > Personality, morality, judgement, etc.
Association Fibers Examples
- Arcuate fibers - Longitudinal fasciculi
Optic Chiasm
- Area where the fibers of the optic nerves (II) cross the opposite side of the brain - Found on top of superior part of pituitary gland
Hypothalamus
- Below the thalamus - Center of homeostasis - Has temperature control center + centers that regulate internal balance - Highest control center over the autonomic motor neurons - Greatly affected by a person's emotional stress > Hypothalamus is wired to limbic system (center of emotions) - Controls release of hormones by the pituitary gland - Links the nervous system + endocrine system via the pituitary gland - Produces hormones
Superior Sagittal Sinus
- Between the right + left cerebral hemispheres in the superior side - Receives blood from cerebral veins - Receives CSF from subarachnoid space via arachnoid granulation
Components That Protect the Brain
- Bones of the skull - Cranial meninges - CSF - Blood brain barrier - Rich blood supply
BBB is Absent In
- Choroid plexus - Hypothalamus - Pituitary gland - Pineal gland
Arachnoid Trabeculae
- Collagen fibers - Anchors the cerebral blood vessels to their place
Pituitary Gland
- Connected by infundibulum to the hypothalamus - Major endocrine gland - Blood brain barrier is absent
Cranial Meninges
- Connective tissue layers that connect the soft tissue of the brain from the skull - Dura mater - Arachnoid mater - Pia mater
Frontal Lobe
- Conscious control of the skeletal muscles - Problem solving, reasoning, planning, etc.
Longitudinal Fissure
- Deep depression - In-between the right + left lobe - Divides right + left hemispheres of the brain
Gyri
- Elevations - Single elevation = gyrus - Increases surface area
Pineal Gland
- Endocrine gland that produces melatonin - Affects modulation of wake sleep patterns - Blood brain barrier is absent
Brain Lobes
- Frontal lobe - Parietal lobe - Occipital lobe - Temporal lobe
Projection Fibers
- Groups of axons that link other regions of the brain spinal cord - Is able to make connections between the cerebrum and other parts of the brain
Why is There No BBB in the Hypothalamus?
- Has the receptors that needs to sense the chemical content of the blood - Needs to have easy access to blood content hormones
Cerebral Cortex
- Having a group of neuronal cell bodies at the surface of CNS - Each hemisphere controls the opposite side of the body - Gray matter on the surface
Transverse Cerebral Fissure
- In-between cerebrum and cerebellum - Deep depression
Sulcus
- In-between gyri - Shallow depression - Creates the different lobes of the brain
Insula
- Inside the cerebrum - Includes: > Gustatory cortex (taste)
Blood Brain Barrier
- Irregulates substances between blood + brain tissue - Made up of capillary endothelial cells - Surrounded + formed by astrocytes - Tight junctions block the passage of material between the endothelial cells - Only lipid soluble compounds are able to go through the lipid bilayer - Allows nutrients to go in and nourish brain tissue - Allows waste to get out of brain tissue
Temporal Lobe
- Lateral sides of the brain - Related to hearing + smelling - Includes: > Auditory cortex > Olfactory cortex
CSF Sequence Through the Brain Ventricles
- Lateral ventricle - Interventricular foramen - Third ventricle - Aqueduct of midbrain - Fourth ventricle LIT AF
Fourth Ventricle
- Located between the pons + cerebellum - Communicates with the central canal of the spinal cord
Cerebellum
- Means "little brain" - Second largest part of the brain - Coordination of complex skeletal muscle movement - Allows us to coordinate repetitive body movements - Has vermis - Has primary fissure - Has folia - Has cerebellum cortex - Has arbor vitae - Has purkinje cells
Oculomotor Nerve (III)
- Motor function - Does NOT control all extrinsic eye muscles > Exceptions: Superior oblique muscle + lateral rectus muscle - Helps move upper eyelids + intrinsic muscles - Responsible for adjusting diameter of pupil (how much light goes into the eye) - Changes shape of lens
Trochlear Nerve (IV)
- Motor function - Goes to one muscle of the eye (superior oblique) - Passes through trochlea on its way to insertion of superior surface of eye - Used to be called pathetic nerve due to causing a head tilt that was a result of damage to this nerve
Hypoglossal Nerve (XII)
- Motor function - Goes towards tongue - Leaves the cranium + passes through the hypoglossal canal of occipital bone - Supplies motor info of the tongue
Accessory Nerve (XI)
- Motor function - Only nerve with cranial root + spinal root - Innervates palate, pharynx, and larynx - Innervates muscles of superior back (sternocleidomastoid + trapezius) - Think accessory you would put on your back such as a backpack
Strictly Motor Cranial Nerves
- Oculomotor nerve (III) - Trochlear nerve (IV) - Abducens nerve (VI) - Accessory nerve (XI) - Hypoglossal nerve (XII)
Cranial Nerves
- Olfactory nerve (I) - Optic nerve (II) - Oculomotor nerve (III) - Trochlear nerve (IV) - Trigeminal nerve (V) - Abducens nerve (VI) - Facial nerve (VII) - Vestibulocochlear nerve (VIII) - Glossopharyngeal nerve (IX) - Vagus nerve (X) - Accessory nerve (XI) - Hypoglossal nerve (XII) OLd OPperators OCcassionally TRObleshoot TRIcycles ABDUcted FACtions VESTIges GLOSSily VAGUe ACcross History
Strictly Sensory Cranial Nerves
- Olfactory nerve (I) - Optic nerve (II) - Vestibulocochlear nerve (VIII)
Directionality of CSF
- One way flow - Directionality of CSF is due to the ciliated ependymal cells - A normal adult replaces about 150 mL of CSF every 8 hours - Ependymal cells takes nutrients from blood to make CSF
Somatosensory Association Area
- Posterior to post-central gyrus - Allows us to understand texture, size, and shape
CSF Functions
- Prevents contact of neural tissue with the surrounding bones - Reduces the weight of the brain from 1500 g to 50 g - Allows brain to float so that it doesn't get crushed on its own weight - Protects brain from blows + other trauma - Transports nutrients to CNS tissue - Transports waste away from the CNS
Arachnoid Granulation
- Projections that go into the superior sagittal sinus - Extensions of the arachnoid mater - CSF is able to reach superior sagittal sinus > Due to fluid pressure, CSF is forced into the bloodstream from the subarachnoid space (gets recycled)
Pons
- Relay station between cerebellum and cerebrum - Coordinates skeletal muscular activity - Has a role in breathing pattern > Has centers that regulate the activity of the respiratory reflex center in the medulla oblongata
Hydrocephalus
- Results from overproduction of CSF - Can also result from obstruction at some point within the ventricular system - Can be related to problems with CSF reabsorption
Medulla Oblongata
- Right under the pons - Connects the brain + spinal cord - Relay station for spinal cord + rest of brainstem - Cardiac + respiratory reflex centers - Vagus nerve (#10) comes out of here - Related to autonomic centers that regulate cardiovascular, respiratory, + digestive systems - Regulates basic vital functions
Layers of Brain (Superficial to Deep)
- Scalp - Epicranial aponeurosis - Periosteum of cranium - Bones of the skull (cranium) - Cranial meninges
Trigeminal Nerve (V)
- Sensory + motor function - Associated with sensation of entire face - Includes teeth + voluntary control of chewing muscles (Ex: masseter)
Facial Nerve (VII)
- Sensory + motor function - Carries sensory info. to anterior 2/3 of the tongue - Innervates lacrimal glands + submandibular + sublingual glands - Controls MOST of the face muscles (facial expression)
Glossopharyngeal Nerve (IX)
- Sensory + motor function - Involved with taste info. of posterior one third of tongue - Sensory functions with baroreceptors + chemoreceptors - Controls parotid glands + some muscles of pharynx - Involved with swallowing
Vagus Nerve (X)
- Sensory + motor function of internal organs - Goes through different regions of the body - Includes the thoracic + abdominal cavities - Innervates respiratory + cardiovascular + digestive organs - Longest nerve
Olfactory Nerves (I)
- Sensory function ---> smell - Aka olfactory bulb - Most anterior part of the brain - Only cranial nerve exposed to the exterior - Shortest cranial nerve - Found inside nose, in the nasal epithelium - Takes information to the cerebrum - Does NOT pass through the thalamus - Forms neuronal masses on either side of crista gali - Bundles of axons passes through cribriform plate
Cranial Pia Mater
- Softest - Delicate connective tissue that attaches to the brain itself - Right on top of cerebral cortex - Contours every gyrus of cerebral cortex - Has blood vessels - Nourishes brain cells
Cranial Dura Mater
- Toughest - Right under the cranium - Two layers: > Periosteal layer > Meningeal layer
Sensory + Motor Cranial Nerves
- Trigeminal nerve (V) - Facial nerve (VII) - Glossopharyngeal nerve (IX) - Vagus nerve (X)
Meningeal Layer
- True layer that covers the brain - Extends the vertebral canal as the spinal dura mater
Median + Lateral Apertures
- Two openings that communicate with subarachnoid space in the brain + spinal cord - This is the way through which CSF leaves the brain from the fourth ventricle - About 90% of CSF travels through here
Choroid Plexus
- Vascularized membrane - "Choroid" = blood vessels - "Plexus" = network - Blood vessels are surrounded by ependymal cells
Interventricular Foramen
Allows communication between the lateral and third ventricle
Aqueduct of Midbrain
Allows communication between third and fourth ventricle
Visual Cortex
Anything you see
Corpus Callosum
Bundle of axons that decussate between the two hemispheres and allows them to communicate with each other
Nutrients Leaving BBB Example
CO2
Association Fibers
Connects areas of the cerebral cortex within the same hemisphere
Epicranial Aponeurosis
Tough layer of dense fibrous tissue
Treatment of Hydrocephalus
Treated by draining CSF by making a little hole in the ventricle + using a little tube to drain it into the abdominal cavity
Periosteum Cranium
Vascular connective tissue that involves the bone
Lateral Sulcus
Divides the temporal lobe from all three other lobes
Jugular Vein
Drains blood out of the brain
Cerebellum Cortex
Gray matter in the surface
Pyramidal Cells
Large neurons that allow conscious control of the skeletal muscle movement
Why is There No BBB in the Pituitary + Pineal Gland?
Needs to release hormones directly into the blood
Purkinje Cells
Neuronal cell bodies responsible for coordinated movement
Associative Reflex Example
Reacting unexpectedly to a loud sound
Granular Layer of Purkinje Cells
- Aka receptive layer - Where axons are found - Inner layer - Has tightly packed small neurons
Sella Turcica
- Feature of the sphenoid bone - Has the pituitary gland sitting on it - Pituitary gland is encased by the diaphragm sellae
Maxillary Branch
- Only sensory function - Passes through foramen rotundum - Sensation on upper teeth
Ophthalmic Branch
- Only sensory function - Passes through superior orbital fissure
Parietal Lobe
- Overall related to sensation - Includes: > Post-central gyrus > Somatosensory association area
Lateral Ventricle
- Paired - Found in the cerebrum hemispheres - Extends from anterior horn (frontal lobe) to posterior horn (occipital lobe) + inferior horn (temporal lobes) - Has no direct connection between the two lateral ventricles - Most of it is located within the parietal lobe
Tentorium Cereblli
Dura mater folds located along the transverse cerebral fissure
Falx Cerebelli
Dura mater folds located between right + left hemispheres of the cerebellum
Falx Cerebri
Dura mater folds located between right + left hemispheres of the cerebrum (along with the longitudinal fissure)
Primary Fissure
Separates the anterior + posterior lobe of the cerebellum
Septum Pellucidum
Separates the two lateral ventricles
Cerebrum
- Biggest area of the brain - Conscious thought process, intellectual functions > Being aware of what is going on (senses + voluntary movement) - Memory storage + thought processing - Conscious + subconscious regulation of skeletal muscle contractions - Has gyri - Has sulcus - Has longitudinal fissure - Has transverse cerebral fissure
Dural Venous Sinus
- Blood filled space caused by the separation of the two dura mater layers - Filled with venous blood - Majority of the blood from the brain drains into it - The jugular vein gets blood supply from this sinus - Veins of the brain empty themselves into this sinus which delivers blood to the internal jugular vein in the neck
Periosteal Layer
- Closer to the skull - Attaches to inner surface of the skull - Layer felt within the anterior fontanelle of a baby - Only found in the brain
Crista Gali
- Feature of the ethmoid bone - Point of attachment in the inferior, anterior aspect of the falx cerebri - Anchors the brain
Commissural Fibers
- Fibers that connect the two hemispheres - Includes: > Corpus callosum > Anterior commissure
Brain Ventricles
- Fluid filled cavities - Has CSF
Diaphragma Sellae
- Fold of the dura mater - Lines the sella turcica - Anchors dura mater to sphenoid bone
Folia of Cerebellum
- Folds - Equivalent to cerebrum gyri
Dura Septa
- Folds - Extensions of the dura mater that goes deep into the brain - Subdivides cranial cavity - Supports the brain - Limits brain movement
Hydrocephalus in Adults
- Found in adults because rigidity of the skull keeps pressure within - Can lead to brain damage due to compression of brain blood vessels + crushes soft nervous tissue
Hydrocephalus in New Borns
- Found in new borns because skull bones are fused together - Causes increased pressure and results in a very large head
Vestibulocochlear Nerve (VIII)
- Sensory function - Comes from the vestibule + cochlea parts of inner ear - Carries sensory info about equilibrium imbalance + hearing info
Thalamus
- Under the epithalamus - Has right + left sides connected via inter-thalamic adhesion - Relay station for all sensory information coming from spinal cord + eyes + ears (95%) - Largest mass (nuclei) of neuronal cell bodies found within the CNS
Infundibulum
Structure that connects pituitary gland and the hypothalamus