Neuroanatomy Flashcards
Peri
around
e.g., perimeter, periaqueductal gray
Para
beside
e.g., paramedic, paraventricular
nucleus
Hypo
below
e.g., hypodermic, hypothalamus
Pre
in front of
e.g., precentral gyrus
Post
after/behind
e.g., postcentral gyrus
Superior/super/supra
above
e.g., superior colliculus,
suprathreshold
Inferior/infra
below
e.g., inferior colliculus
Epi
on top of
e.g., epiglottis, epithalamus
Ipsi
same
e.g., ipsilateral
Contra
opposite
e.g., contralateral
Rostral
towards nostril
Caudal
towards trail
Dorsal
towards back
Ventral
towards belly
Medial
towards midline
Lateral
away from midline towards side
Forebrain
Ventricle: Lateral and Third
Subdivision: Telencephalon (lateral) and Diencephalon (third)
Telencephalon principal structures: cerebral cortex, basal ganglia
Every major sensory system except for … makes a stop in the thalamus
Smell
Retino-geniculo-calcarine Pathway just structures
Retinal ganglion cells → LGN (where synapse of these axons occur) → Striate Cortex (AKA V1 or Area 17)
Retino-geniculo-calcarine Pathway specific
Whatever we see is projected onto the retina and the retinal ganglion cells will respond to stimulus. They have axons that extend into a bundle which is called the optic nerve (cranial nerve #2). Bundle of axons coming from retinal ganglion cells will cross here forming an “x”, hence the name optic chiasm but still continue on after the crossing. Crossing over official name: decussate which means crossing the midline to go to the contralateral side. After the chiasm, they are now called the optic tract. Same axons, different names. No synapse yet!
First synapse in the thalamus, specifically the lateral geniculate nucleus (LGN). LGN sends its own axons (projects) to the back of the brain to the caudal end of the occipital lobe, specifically V1=striate cortex= Area 17. Area 17 hugs the calcarine fissure.
What happens if V1 is destroyed?
If V1 is destroyed, then the person will be blind but they will still walk around objects blocking a straight pathway and will duck when punched. Visual info is still somehow coming across and this process is called “blindsight”
What does Tectofungal Visual Pathway allow for?
allows for unconscious habitual visual reflexes
Tectofungal Visual Pathway just structures
Both retinas’ retinal ganglion cells → Superior colliculus (Mesencephalon) → Pulvinar Nuc. Of Thalamus (Diencephalon) → Extrastriate Cortex = V2 & V3 = Areas 18 & 19
Tectofungal Visual Pathway long answer
Whatever we see is projected onto the retina and the retinal ganglion cells will respond to stimulus. They have axons that extend into a bundle which is called the optic nerve (cranial nerve #2). Bundle of axons coming from retinal ganglion cells will cross here forming an “x”, hence the name optic chiasm but still continue on after the crossing. Crossing over official name: decussate which means crossing the midline to go to the contralateral side. After the chiasm, they are now called the optic tract. Same axons, different names. Superior colliculus (Mesencephalon) → Pulvinar Nuc. Of Thalamus (Diencephalon) → Extrastriate Cortex = V2 & V3 = Areas 18 & 19
Superior colliculus (Mesencephalon)
two bumps above the two inferior colliculus. Can only see if you separate the cerebellum from the brain.
How does tunnel vision happen?
Tumor can occur at chiasm which will block crossing over. Only ipsilateral things can go through. Interruption on both so you get tunnel vision. You lose extreme peripheral vision
Non-Neural Tissue (Meninges)
Dura mater: outermost, thick tough layer which covers the entire brian. Looks white, thick, and plasticy. Actually it consists of 2 layers but we look at it as one.
Cranial Nerves attached here.
Arachnoid: Transparent softer middle layer. Looks like shrink wrap so it allows you to see blood vessels, which look like spider webs, hence the name. Covers everything.
Pia mater: Thin/soft layer which hugs the surface of CNS intimately in every nook and cranny. Can only see with a microscope b/c only a couple cells thick.
Meningitis
Meninges = 3 layers which cover the brain/spinal cord
Meningitis: inflammation of these layers which can be with bacterial (dangerous/fatal but antibiotics can fight it) or viral (caused by virus, no treatment, tamer version)
Hypothalamus
structure of diencephalon located anterior and inferior to thalamus. Has both neural + endocrine functions. Connects to pituitary gland through infundibulum.
Pituitary Gland
Master gland of endocrine system b/c it releases hormones that tell others what to do. Reports to hypothalamus.
Anterior Pituitary Gland
What does it release?
Controlled by hypothalamus but there is no neural connection between the two.
Hypothalamus will release GnRH and TRH that are instructions into the bloodstream. Blood vessels will pick these hormones up to take to the anterior. The ring of cells around infundibulum called median eminence will release whichever hormones it tells it too. Two gonadotropin examples: FSH and LH.
GnRH, FSH, LH, TRH
GnRH: gonadotropin-releasing hormone
FSH: promotes maturation of the follicle and stimulates production of estrogen + progesterone in females and sperm cells in males
LH: regulates ovulation in females and stimulates production of testosterone in males
TRH: thyrotropin releasing hormone
Anterior Pituitary Gland
Regulation
Emotional and exteroceptive influence via afferent nerves to hypothalamus. Neurosecretion of releasing factors and inhibitory factors from hypothalamus into the primary plexus of hypophyseal portal circulation. Hypophyseal portal veins carry neurosecretions to the anterior lobe. Specific secretory cells of anterior pituitary (adenohypophysis) influenced by neurosecretions from the hypothalamus
Posterior Lobe Pituitary Gland
Supraoptic and paraventricular nucleus (parts of the hypothalamus) will make and release the hormones: ADH (vasopressin) and oxytocin. They travel through median eminence and infundibulum which connects the hypothalamus to the posterior pituitary gland. From here, ADH (vasopressin) and oxytocin are released.
ADH + Oxytocin
ADH (vasopressin) Supraoptic: anti-dieutric hormone which regulates salt and water content in the blood by affecting water retention
Oxytocin (paraventricular): uterine contractions during childbirth and lactation
posterior pg
Cranial Nerve I
Olfactory
Smell-related. Small but won’t see it so just point to olfactory bulb since that is where it projects to.
Cranial Nerve II
Optic: Visual-related. Bundle of axons belonging to retinal ganglion cells that transfer visual information from the retina to vision centers in the brain. Form optic chiasm now called the optic tract.
Cranial Nerve IV
Trochlear: Allows you to move the eyes to look down and up as well as side to side at the same time, such as towards the nose. Moves the superior oblique muscle.
Cranial Nerve III
Oculomotor: Responsible for eyeball and eyelid movement. Thick.
Cranial Nerve V
Trigeminal: Thickest. Innervates muscles of the masseter for chewing, such as jaw. Carries info of sensation to the face including oral cavity and teeth and texture for anterior 2/3 tongue.
Cranial Nerve VI
Abducens: Move eye from side to side laterally through adducting.
Cranial Nerve VII
Facial: Innervates the muscle for facial expression. Carries taste info from anterior ⅔ on tongue.
Cranial Nerve VIII
Vestibulocochlear: Responsible for balance + hearing. Transmits sound and equilibrium info from inner ear to brain.
Bell’s Palsy
Facial nerve inflammation leads to facial weakness or paralysis
Cranial Nerve IX
Glossopharyngeal: Innervates muscle of the throat. Sensation and taste info from the posterior ⅓ of the tongue. Sensation to the tonsil, pharynx, and middle ear.
Cranial Nerve X
Vagus: Innervates visceral organs. Parasympathetic (rest + digest) outputs on visceral organs.
Cranial Nerve XI
Spinal Accessory: Innervates trapezius muscles such as shoulder shrugging. Provides motor function to the sternocleidomastoid muscle.
Cranial Nerve XII
Hypoglossal: Innervates muscles of the tongue.
Human Brain + Blood Supply
Fresh oxygenated blood comes up the two branches of the vertebral artery. They join to become the basilar artery at the pons. Branch again outward at the base of the circle to become posterior cerebral. Connect to middle cerebral artery via Posterior communicating artery. Two branches of the middle cerebral turn into anterior cerebral arteries as we move up. Anterior cerebral arteries joined via Anterior communicating arteries.
Where does anterior cerebral artery provide blood for?
Anterior cerebral artery provides blood for the top of the brain and down the middle between the hemispheres (middle + superior parts of frontal + anterior parietal).
Where does middle cerebral artery provide blood for?
Middle cerebral artery provides blood for the sides of the brain.
sides of the brain: temporal lobe, parietal and frontal
Where does posterior cerebral artery provide blood for?
Posterior cerebral artery provides blood for the back of the brain (occipital + inferior temporal).
What happens if you no longer can get blood?
Outside circle of willis
No longer getting blood = stroke. If blockage outside of the circle, cells will die. Examples of what will happen if blockage occurs at end of middle cerebral artery:
Can get global aphasia (Broca’s + Wernicke’s.)
Motor Cortex (Frontal Lobe): precentral gyrus - motor problems like paralysis
Paralysis can be flaccid or spastic. Upper motor neurons damage = spastic of contralateral side.
Somatosensory Cortex (Parietal Lobe): postcentral gyrus - loss of somatosensation (contralateral)
Loss of auditory function b/c damage to auditory area (bilateral)
What happens if you no longer can get blood?
Inside circle of willis
If blockage inside the circle, less severe symptoms b/c the circle will compensate. Most people don’t know until they get an angiogram.
External Features: Myelencephalon
pyramids and their decussation (corticospinal tract)
Pyramids
Pyramids are axons that belong to the corticospinal tract, a descending motor tract. Bundles of axons can start crossing over contralaterally (decussation.)
Myelencephalon
Principal structure: Medulla Oblongata
Major Division: Hindbrain
Ventricle: Fourth
External Features: Metencephalon
Trapezoid body: where dorsal cochlear nuclei fold into a bundle
Cerebellum: motor coordination + balance (fine details). Sensitive to alcohol.
Vernis: looks like an earthworm medial in cerebellum. Lesions result in posture problems. In cerebral cortex.
Folia: bumps/gyruses on cerebellum
Pons: motor-related and sends out inhibitory signals to muscles in your sleep (ventral)
Middle Cerebellar Peduncle (brachium pontis): arms of the pons; sends axons to the cerebellum (copy of info from the corticospinal tract) (Corticopontocerebellar tract)
Metencephalon
Major Division: Hindbrain
Ventricle: Fourth
Principle structures: cerebellum and pons
External Features: Mesencephalon
4 Bumps: Corpora Quadrigemina
Superior colliculus: Top two. Part of unconscious reflexes from retinal ganglion cells.
Inferior colliculus: Bottom two. Part of the auditory system.
Cerebral Peduncles: (Crus cerebri) (corticospinal tract). Axons of corticospinal cord. ( Dorsal)
Mesencephalon
Major Division: Midbrain
Ventricle: Cerebral Aqueduct
Principal Structure: Tectum Tegmentum
External Features: Diencephalon
Hypothalamus: produces releasing hormones. Fear/sexual motivation/aggression
Median eminence/Tuber cinereum: bring to anterior pituitary gland
Mammillary bodies: right underneath. Look like balls. Part of the limbic system. Role in memory
Mammilary body damage
(anterograde amnesia).
Diencephalon
Major Division: Forebrain
Ventricle: Third
Other Principal Structure: thalamus
External Features: Telencephalon
Cortex (everything in your hand when you hold the brain)
Corpus callosum: connects the hemispheres’ cortexes. White matter tract
Rhinencephalon: rhinal = nose cephalon = brain. Olfaction role.
Rhinal Fissure (External Features: Telencephalon)
acts as border
Olfactory bulb + 2 lateral olfactory tracts (External Features: Telencephalon)
olfactory bulb gives rise to two lateral olfactory tracts. Pear-shaped
lateral olfactory tract: bundle of axons that go from olfactory bulb to pyriform cortex
pyriform cortex/area:
entorhinal cortex- landmark for hippocampus. Below pituitary gland
Uncus- landmark for amygdala. Above hippocampus
Afferent Auditory Pathways + hearing loss
Hearing loss can be bilateral.
Unilateral hearing loss can happen if damage is in cochlea (snail-shaped) which extends to Cranial Nerve VIII, vestibulocochlear nerve
Auditory Pathway
Ventral cochlear nucleus projects to these two structures: Superior olivary complex (which gets info from both sides)
One synapses on the ipsilateral side. The other synapses on contralateral side which forms a bundle of axons that crosses the midline on the way leading to a bump on the ventral surface of the brain: Trapezoid body (decussating fibers)
Superior olivary complex sends info from lateral lemniscus that ascends to inferior colliculus.
Dorsal cochlear nucleus sends info from lateral lemniscus that ascends to inferior colliculus.
Both sides of inferior colliculus talk to each other. Lots of crossing over
Thalamic stop: Medial geniculate nucleus (MGN)
Projects to auditory cortex (Area 41) (Area A1)
Superior olives + pena + localization
Superior olives where some localization happens in the horizontal plane.
Get activated at different times depending on which direction noise comes from. Interaural time difference + intensity difference will affect excitation rates of the superior olives.
Pena: vertical plane localization
Difference between ventral and dorsal cochlear nuclei
Ventral cochlear nucleus projects to these two structures: Superior olivary complex (which gets info from both sides)
One synapses on the ipsilateral side. The other synapses on contralateral side which forms a bundle of axons that crosses the midline on the way leading to a bump on the ventral surface of the brain: Trapezoid body (decussating fibers)
Superior olivary complex sends info from lateral lemniscus that ascends to inferior colliculus.
Dorsal cochlear nucleus sends info from lateral lemniscus that ascends to inferior colliculus.
Somatosensory
Organization of spinal cord
Dorsal= up Ventral= down