Neuroanatomy & Function II Flashcards
where are the respiration centers located within the brain
respiration center controls: for inhalation and exhalation are controlled in the pons and the medulla
thus, injury to the pons and medulla in these specific locations can result in respiratory issues such as dyspnea
where are cardiac control centers located wtihin the brain
responses from the baro and chemoreceptors are taken in by the rostral and caudal ventrolateral medulla
where is the reticular activating system of the brain
what is it responsible for
what does this connect (areas/structures within the brain)
The Retiuclar Activating System (RAS) is the system within the brainstem (areas of nuclei found throughout the midbrain, pons and medulla) responsible for arousal/consciousness and wakefulness
Lesions in the RAs can lead to obtunded pts, stupor, and coma presentations
Nuclei Names
- pedunculpontine nuclei
- locus cercules
- raphe nuclei
- reticualr nuclei
- parvocellular nuclei
the RAS connects the brainstem to the thalmus & then to the cortex through a series of NT connections
RAS is seen as the connection between the thalmus and the cortex
What is the Hippocampus
how is memory related to this area
what are the two memory pathways
Hippocampus: a struture (swirled) that sits just below the pre-hippocampal gyrus in the temporal lobe
Hippocampus: is the area of memory retrevial and consolidation not memory storage!!
subbreakdown of the hippocampus
CA1, CA2, CA3 & CA4
Memory Pathways
1. Tri-synaptic Circuit: encoding, consolidation & retrevial of memories
2. Circuit of Papex: Connects the hippocampus to limbic, ANS and other systems (which is why memories can be emotional!)
Explain the Tri-Synaptic Circuit of Hippocampal Memory
Explain the Circuitof Papez of Hippocampa Memory
Tri-Synaptic Circuit (tri think CA3 before CA1)
- entorhinal cortex –> dentate gyrus
- dentate –> CA3
- CA3 –> CA1
Circuit of Papez
- subiculum (in hippocamp) –> travel to the Mamillary Bodies via the Fornix
- mamillary bodies –> anterior nucleus o the thalamus
- anterior nucleus to the cingulate gyrus
- cingulate gyrus to parahippocampal gyrus
- parahippo. to the entorhinal cortex
what is the Limbic System
what strucutres are involved
Limbic System: involved in emotion, drive and basic behaviors
- the emotion, memory and autonomic regualtion related
- related to other pathways (reason for memories being related to stress, fear, anger, etc.)
Structures
- Amygdala (near hippocampus)
- hippocampus
- Olfactory Blub (smells = memorie!)
- Fornix
- Hypothalmus
CNS: Blood Supply
2 origins of the blood supply from what arteries
three main branches to know
where does the MCA run? the ACA?
Origins of Supply
- the two internal carotid arteries (from common carotids)
- the two vertebral arteries
Branching
- the vertebral arteries come together to form the basilar artey: the main posterior blood supply of the brain
- the internal caroitd arteris give rise to the MCA (middle cerebral artery) and the ACA (anterior cerebral artery) which are the main supplies of the anterior brain
MCA: runs within the lateral fissure
ACA: runs within the longitudinal fissure
Circle of Willis
- the basilar artery (supplied by the vertebral arteries)
- Basilar: gives off arteries which supply the cerebellum (the superior cerebellar, the anterior inferior cerebellar and the posterior inferior cerebellar) & pontine arteries
- the posterior cerebral artery: connects to basialr and to the posterior communicating artery
- the middle cerebra artery: gives rise to the opthalmic artery
- the anterior cerebral artery: gives rise to the anterior communicating
the arteries which make up the circle
- basilar artery
- posterior cerebral artery
- internal carotid/middle cerebral artery
- anterior cerebral artery
- posterior communicating artery (allows for collateral blood supply)
- anterior communicating artery
what areas are supplied by the MCA and ACA
what about the posterior circulation of the brain
MCA: supplies the lateral aspects of the brian’s cortex
ACA: suppleis the medial aspect of the brain’s cortex
Posterior Circulation
- PCA: supplies parts of the occipital, superior cerebellum
- cerebellum: superior cerebellar a, anterior inferior & posterior inferior
- thalmus: PCA, ICA (internal carotid)
- midbrain: PCA, SCA, BA
- Pons: BA, PICA
- MEdulla: VA, PICA
Venous Drainage of the Brain
Venous Drainage occurs through the Venous Sinuses
- no valves (meaning the flow is natrual and gravity dependent) but this means back flow can occur (like standing on your head for too long)
- eventually all draiins to the internal jugular vein and into the SVC
Sinues
- Left and Righ Cavernous Sinuses
- Superior Sagittal
- Inferior Sagittal Sinuses (connects via Straight sinus)
- Confluence of sinuses
- into the transverse sinuses
- to the sigmoid sinus
- to the internal jugular
what is the cavernous sinus
what NV strucutres pass through it
risk of infection
Cavernous Sinus: an area of blood which pools in the brain sinuses for a moment, used as a cooling system in order to cool down incoming arterial blood through the internal carotid artery
- lined with dura
- risk of infection and thrombosis: infection because the facial vein also drains here: “danger zone” of infection on the face can get to the brain
Strucutres which pass WITHIN the Cavernous Sinuses
- internal carotids
- CN V1 and V2 (opthalmic and maxillary nerves of the trigem.)
- Abducens (VI) and Trochlear (IV)
- Occulomotor III
(in sum, internal caroitd, III, IV, VI and V1 and V2)
lacunar Infarcts
- where will the impact be
Lacunar Infarcts: common because they are infarcts of smal vessels deeper in the brain which can be asymptomatic
- uncontroleld HTN plays a big role here
- internal capsule and thalamus can be affected with these
Meninges
3 layers and their order
where are vessles (arteries? veins?)
Mengines: outer coverings of the brain
- Dura Mater: hard outer most layer
- Arachnoid Mater: middle
- Pia Mater: inner most (almost glued to the brain itself)
Arachnoid Mater Specifics
what is within
Arachnoid Mater
- subarachnoid space: CSF flows here
- continuous with the SC
- more arteries can be found in teh subarachnoid space
Dura Mater Specifics
what is above and below
septa?
innervation and blood supply
Dura Mater
- makes up the folds within the brain (the sinuses)
- EPidural (above dura): this space contains fat, arteries, lymph, etc.
- SUBdural (below the dura): this space contains veins
- dura not continuous with the SC
Dural Septa (Divisions)
- Falx Cerebri (divides the cerebral cortex) (cignulate gyri under here in herniation)
- tentorum cerebelli: divides teh cerebral cortex from the cerebellum (uncal herniation under this)
Innervated : trigeminal n.
blood: middle meningeal artery
the dura splits to creat sinues, allowsing scalp drainge here too & risk for infection to occur
CSF & Ventricles
- where is it made
- what is it
- how does it flow
CSF: cerebral spinal fluid
- basically blood, full of nutrients and acts as a cushion for the brain
- CSF is more acidic than blood however, thus metablic changes may impact the CSF more than blood would be infected (less able to buffer changes in pH)
- CSF 7.33 (plasma 7.41)
- CSF is made in the ependymal cells of the choroid plexus & then reabsorbed by arachnoid granulations in the dural sinuses
CSF : is within the subarachnoid space: continuous with the ventricles and cisterns of the brain
black on T1, white on T2 imaging
ICP: normal is 5-15
Ventricles
- Left and Right Lateral (2)
- connected to 3rd by foramina munro
- 3rd Ventricle
- 3rd connected to 4th by cerebral aqueduct
- 4th Ventricle
- drained by the central canal of the SC to the spinal cord
Cistern: a space where CSF pools: arachnoid is loose
hydrocephalus = increased CSF: can be comunicaing (between all ventricles just not absorbed) or non-communicating (blockage)
how is the BBB maintained
Blood Brain Barrier: maintained by tight junctions within the epithelium;in addition to astocyte foot processes to ensure the tight junction is tighter!
- allows water, oxygen, Co2 and glucose to pass but nothing else
Weak points in the BBB are by the pituitary and the circumventricualr regions
Autonomic Nervous system
breakdown
what brain areas involved
Autonomic Nervous System: automatic! regulates bodily functions
CNS components
- hypothalmus!!
- brainstem
- spinal cord
Efferent Branches (Motor)
Sympathetic: from T1-L2 (thoracolumbar) lateral horns
Parasympathetic: Craniosacral Division: Cranial Nerves & S1-S4 nuclei (collection of cell bodies)
Afferent Branches (Sensory)
- Visceral Afferent (from the organs) : travel on the sympa or parasympa nerves going to the spinal cord: travel through the DRG (like normal sensory nerves do)
Somatic Sensory Nerves: are afferent going to the brain/SC: these are skin and special senses which travel from their target to the SC, the DRG
Exact Pathway of the Sympathetic Nerve Pathway (Efferent) aka how does the signal to increase HR or something get to the target
we know that the sympathetic nerves are those within the thoracolumbar (T1-L2) spinal nerves
lateral horn = motor
Preganglonic nerves: in the lateral horns of the thoracolumbar SC
they travel to the sympathetic chain (directly next to where the nerve roots exit)
SYNPASE
postganglonic neurons: exist in the sympathetic chain/ganglia and then travel to the target organ to do their job
ACh for the pregang.
Norepi for the postgang.
(for sympathetic response which need to travel back tot he head and neck: thye travel up the sympathetic chain to the superior cervical ganglion (SCG) where they synpase and then get to target) lesion at the SCG can cause sympathetic disregulation : like horners!!! (all things of parasymp. becuase sympa. is cut)
Parasympathic innervation effernt pathway
motor pathway for parasympathetic innervation
rest and digest
preganglonic neurons: are within teh crainal nerve cell bodies or the cell bodies of S1-S4 still in the lateral horn since its motor
these travel ALL the way almost to the target organ
SYNPASE
postganglonic neurons: are cell bodies withint ganglia that sit like directly next to the target organ
(ACh is the NT for the presymp and post)
enteric NS
the independent NS of the GI tract : peristalsis movement regulator
- still recieves parasymp and sympa. innervation too!
Autonomic Nervous System Receptors
preganglionic: ACh receptors (cholenergic) aka muscarinic or nicotinic
postganglonic (sympa): norepi (adrenergic) receptors
Cranial Nerves
basic facts
types of nerves
where are the cell bodies
deficts indicate what
CN 1-12: are considered peripheral nerves: mixed sensory,motor and carry autonomic functions
cell bodies: contained within nuceli in the brainstem, face and skull
deficts in the peripheral cranial nerves indicat a lesion to the CN of the SAME SIDE (except trochlear (CN IV)
CN I
CN I = olfactory nerve (sense of smell)
- through cribiform plate in the ethmoid bone
- regenrate
CN II
type of nerve
pathway
CN II: optic nerve
pure sensory nerve : detects vision
- recall the optic pathway
- lesions location within the pathway indicates type of vision lost
CN III
type of nerve
pathway
lesions
CN III: occulomotor
- responsible for somatic (conscious) efferent (motor) action of the eye muscles
- also carries parasympathetic innervation to the iris and cillary muscles: contrsction of pupil and contraction of lens to allow for near vision
all eye muscles (EOM) except superior oblique & lateral rectus
Innervation to the levator palebrae superior (eyelid) to open
lesions
- of the CN III: result in the IV and VI to take over: “down and out” gaze
- impact of the parasymp functions: dilated pupil
CN IV
function
pathway (specifically)
lesions
CN IV: Trochlear Nerve
- responsible for somatic efferent (motor) control of the superior oblique muscle
Pathway
- the CN IV for the L and R = CROSS OVER each other and go to the opposite eye before exiting midbrain
LEsions
- inability to see down and in: so tracking to Up and Out only
- head tilt toward the UNAFFECTED side
CN VI
function
lesions
CN VI: abducens nerve
- responsible for motor movement of the lateral rectus muscle
Lesion s
- impaired abilit to track: cant move eye laterally
CN V
Function
arms of the nerve
CN V = Trigeminal Nerve
- responsible for somatic afferent (sensory) to the face
- afferent reason for teh blink reflex
- responsible for somatic efferent (motor) ability of the muscles of mastication
V1 = opthalmic branch
- sensory to the upper face (forehead and nose)
- blink reflex
V2 = Maxillary branch
- sensory to the cheek and upper lip and upper teeth
V3 = Mandibular branch
- motor to the muscles of mastication
- sensory to the lower chin, jaw, teeth
CN VII
function
lesions
CN VII: Facial nerve
- somatic efferent (motor) to the muscles of the face (facial expression!)
- blink reflex (motor) aspect
- special sensory (taste to 2/3 anterior tongue
- parasympathetic to salviary and lacrimal glands
Lesions
- facial droop! (Bell’s Palsy)
CN VIII
function
lesions
CN VIII = Vestibulocochlear nerve
- special sensory: hearing and vesrtibular sensations
- cochear nerve branch
- vestibular nerve branch
Lesions
- hearing loss
- vertiog, etc.
-
CN IX
function
lesions
CN IX = glossopharyngeal nerve
Functions
- sensory: middle ear, gag reflex
- touch AND TASTE sensation to posterior 1/3 tongue
- parasymp. to parotid gland
- detect BP cahnges via carotid bodies
CN X
function
lesions
CN X = Vagus Nerve
- somatic sensation to larynx, external ear (some)
- parasymp to abd and thorax (diaphragam)
- motor: to gag reflex
- sensory: baroreceptors and taste on epiglottis
Lesions
- speech/swallow issues
CN XI
function lesions
CN XI = Spinal Accessory Muscle
Function
- somatic efferent (motor) to the trapezius and SCM
LEsions
- weak shoulders or head rotation
CN XII
function
lesions
CN XII: hypoglossal Nerve
function
- somatic effernt (motor) to tonguemuscles
LEsions
- tongue deviates to the AFFECTED side
4 Key CN Ganglia to Know
Clilary Ganglion
- CN III
- parasympa.
Trigeminal Ganglion
- CN V
- sensory cell bodies here
Pterygoplatine Ganglion
- CN 7
- parasympathetic to lacrimal
Otic Ganglion
- CN IX
- parasympa. to parotid gland
Gengiculate Ganglion
- CN VII
- sensory to tongue
SUbmandibular Gnaglion
- CN VII
- parasympa. to sublingual and submandib. glands
