NeuroAnatomy Flashcards
- Ventral –
- Dorsal –
- Cranial –
- Caudal –
- Rostral –
- Ventral – ‘front’
- Dorsal – ‘back’
- Cranial – ‘towards the head’
- Caudal – ‘towards the tail’
- Rostral – ‘towards the beak’
what are the two divisions of the forebrain?
telencephalon = cerebrum
diencephalon
what are the two divisions of the hindbrain?
Metecephalon = pons + cerebellum
Myelenceohalon = medulla oblongata
name all the embryobic divisions of the brain.
what is white matter?
why is it white?
nerve cell axons. They appear white due to the presence of myelin sheaths wrapped around the axons which speed up conduction.
what is grey matter?
primarily nerve cell bodies, including their nuclei, but also consists of other nervous system cells including astrocytes, oligodendrocytes or unmyelinated axons.
in the cerebrum, where is most of the grey matter located?
Cerebrum:
- outer = grey
- inner = white
in the spinal chord where is most of the grey matter located?
Spinal Chord
- outer = white tracts
- inner = H-shaped grey centre
what is the cortex of the brain?
the outer part of the cerebrum and cerebellum. Mainly grey matter.
what does the term nucleus refer to in neuroanatomy?
what colour are do they appear and where are they found?
groups of functionally similar or
anatomically related nerve cells
appear grey in large groups
found deep in brain (therefore grey not just on surface)
what is a tract?
a pathway of nerve fibres
no synapses in b
A tract may include a single group of nerve fibres with
no synapses in between the start and end of the tract, or it may include two or three
nerve fibres which synapse along the tract to pass information along.
what is a fossa?
indentation / shallow depression
what is a foramen?
opening/hole/passsage
what is the function of the frontal lobe?
- primary motor cortex
- planning and executing concious movement
- prefrontal cortex = behaviour, personality, decision making
what is the function of the temporal lobe?
- primary auditoy cortex
- hippo campus = memory formation
what is the function of the parietal lobes?
- primary somatosensory cortex
= process sensory information
What is the function of the occiptal lobe?
- primary visual cortex
what is the function of the cerebellum?
posture, balance, fine movement correction
what is the function of the brainstem?
connects the rest of the brain to the spinal cord. It contains the nuclei of the cranial nerves and contains vital centres for regulating breathing and cardiovascular
function.
what is a gyri?
bulge/crest/fold
what is a sulci?
groove/furrow
what does the central sulcus separate?
the frontal and parietal lobes
what does the lateral sulcus separate?
temporal lobe from the frontal and parietal lobe
what three components make up the brainstem?
midbrain, pons and medulla
what would you find if you teased the lateral sulcus appart?
the insula and opercula
* Insula – this is a part of the cerebral cortex that can only be seen by opening the lateral sulcus in this way. In some resources, it is considered to be a fifth lobe.
* Opercula – this term means ‘lid’ or ‘cover’. It refers to the parts of the frontal, parietal
and temporal lobes that cover the insula like lips around a mouth.
name the three sulcu/ fissures of the brain
Longitudinal fissure (left- right)
Central sulcus (frontal- parietal)
Lateral sulcus (Temporal- frontal parietal)
what would you find on separating the longitudinal fissure?
Corpus callosum – this is a large bundle of white matter (axons) that connects the two
hemispheres.
what are the olfactory tracts?
these are nerve fibres carrying information about smell from the nasal
cavity. They run along the inferior surface of the frontal lobes on both sides.
what are the optic nerves?
these nerves carry visual information from the retinas of the eyes. They’re
also seen on the inferior surface of the frontal lobe and pass posteriorly and medially, to
a point where they partly cross over each other (the optic chiasm).
what are the mammillary bodies?
these rounded structures are found just behind the optic chiasm and pituitary gland. They are part of the diencephalon.
where is the hypothalamus anatomically?
this is part of the diencephalon and is only just visible behind the optic chiasm. The mammillary bodies are located on its most inferior surface.
what are the crus cerebri?
this term means ‘feet of the brain’. They are pillars of white matter next to
the mammillary bodies that connect the rest of the brain to the brainstem. They form
part of the cerebral peduncles which are part of the midbrain.
what is the interpeduncular fossa?
this is the name of the fossa between the cerebral peduncles. It may have a layer of arachnoid mater overlying it on some brain specimens.
Where is the primary motor cortex?
posterior frontal lobe
which part of the brain is repsonsible for planning movements?
premotor cortex in frontal lobe
which are of brain is responsible for personality, behaviour, problem solving, impulse control and inhibition, and social
and sexual behaviour
prefrontal cortex in frontal lobe
where is brocas are found and what does it do?
the inferior frontal lobe of the dominant
hemisphere (normally the left) and is important for spoken language production.
where is wernickes are found and what does it do?
the most superior and posterior part of the dominant temporal lobe. It is important in understanding and coordinating spoken language.
what is the lymbic system made up from and what does it do?
hippocampus, amygdala, cortex and diecephalon.
As a group, they are involved in emotion, memory and behaviour. It has influence over the endocrine functions of the body and parts of it are specifically related to the
sensations of fear, pleasure and rewarding behaviours.
where is the amygalda found and what is it responsible for?
located deep within the temporal lobe, and it has a role in the perception of fear
in a homonculus, where are the face and mouth represented, where are the upper limb represented, and where are the lower limb represneted?
lateral = face and mouth
medial = feet
superior = upper limb
what are the two layers of the dura mater?
endosteal layer (outer)
meningeal layer (inner)
The inner meningeal layer completely envelops the brain and spinal cord. The
meningeal layer peels away from the endosteal layer in certain places and folds down
into the brain to form a double layer of dura that separates certain parts of the brain.
what is the falx cerebri?
is a double layer of folded dura lying in the longitudinal fissure
that separates the two cerebral hemispheres.
what separates the occipital lobe from the cerebellum?
tentorium cerebelli
what separates the two lobes of the cerebellum?
falx cerebelli
how are the dural venuous sinuses formed?
the outer endosteal and inner meningeal layer of the dura breifly pull apart from eachother, forming small channels filled with venous blood.
not shown = cavernous sinus
these ‘cave-like’ sinuses are found anteriorly, either side of the sella
turcica of the sphenoid bone. The internal carotid artery passes through it, along with
some important nerves.
where is cerebrospinal fluid made?
Choroid plexus of later third and fourth ventricles
what is the blood-brain barrier made from?
layer of pia and endotherlial cells
what features of the blood-brain barrier allow it to limit the passage of harmful substances?
- endothelial cells
- basement membran not fenestrates
- pericytes
- astrocytes
- The endothelial cells are tightly bonded together to prevent molecules passing between
them. - The basement membrane of the capillaries in the brain and spinal cord lacks fenestrations (small holes) that are found elsewhere in the body.
- Further specialised cells known as ‘pericytes’ wrap around the endothelial cells to regulate blood flow and permeability.
- CNS cells called ‘astrocytes’ have specialised projections called ‘end feet’ that further wrap around the capillaries to restrict flow of certain molecules.
label the pathologies
left = extradural heamorrhage
middle = subdural haematoma
right = subarachnoid haemorrhage
extradural = endosteal layer of the dura is tightly stuck to the inside of the skull, meaning blood
trapped outside of it bulges inwards and cannot spread around the side of the brain.
subdural = Unlike in the extradural space, the arachnoid and dura are not adherent to each other, so blood can easily spread around the sides of the brain causing the crescent appearance
subarachnoid = Blood leaks into the subarachnoid cisterns, mixing with the CSF, sometimes causing a white star-shaped pattern on a CT scan.
arterial blood supply to the brain comes from which arteries (pairs)?
what do they form together?
Internal carotid arteries (80%)
vertebral arteries (20% posterior)
= circle of willis
label the circle of willis
what does the anterior cerebral artery (ACA) supply?
medial aspects of the frontal and parietal lobes, and a strip of cortex on the superior aspect. Plus anterior diencephalon
- motor and somatosensory cortex of lower limbs.
what does the middle cerebral artery MCA supply?
vast majority of the lateral aspects and deep parts of the hemispheres. Plus some diencephalon
- motor and somatosensory of face arms trunk
- internal capsule (transmits all fibres to and from corticles)
What does the Posterior cerebral artery (PCA) supply?
the occipital lobe which contains the visual cortex, but also a small portion of the inferior temporal lobe.
What does the Basilar artery supply?
Pons
- As the pons forms part of the pathway of between
the brain and spinal cord, disruption of the basilar artery can potentially threaten the function of all ascending and descending fibres including all motor control and sensation from the neck down.
what do the cerebellar arteries (AICA, PICA SCA) supply?
Cerebellum
(plus parts of brainstem with basilar)
what makes up the anterior circulation of the brain?
ACA and MCA
what forms the posterior circulation of the brain?
PCA, Basilar and Cerebellar
what is a stroke?
A stroke is an interruption to the blood supply of part of the brain leading to a neurological
deficit that lasts longer than 24 hours.
ischeamic/haemorrhagic
in the brain, venous blood is drained from [a] into [b] before passing into the veins to be returned to the heart
The venous drainage of the brain is unique in that venous blood is drained from smaller cerebral
veins into large dural venous sinuses before passing back into veins to be returned to the heart.
- Cerebral venous blood first drains into [a], which are located deep within the brain tissue.
- The [a] then drain into larger [b] which can be seen on the surface of the brain.
- The [b] then drain into the [c].
- The [c] can drain the blood into extracranial veins via two routes:
o The [d] become the [e] as they exit the skull.
o [f] cross the endosteal layer of dura and drain the venous blood into the bones of the skull.
- Cerebral venous blood first drains into internal cerebral veins, which are located deep
within the brain tissue. - The internal cerebral veins then drain into larger external cerebral veins which can be
seen on the surface of the brain. - The external cerebral veins then drain into the dural venous sinuses.
o These are discussed in the meninges section above, under Dura Mater. - The dural venous sinuses can drain the blood into extracranial veins via two routes:
o The sigmoid sinuses become the internal jugular veins as they exit the skull.
o Emissary veins cross the endosteal layer of dura and drain the venous blood into
the bones of the skull
what passes through the cavermous sinus (behind orbit)
why is this clinically relevant?
internal carotid, (III) (IV) (V1) (V2) (VI)
The cavernous sinus is the only site in the body where an artery (internal carotid) passes completely through a venous structure.
Venous blood draining from the face can potentially drain into the cavernous sinus, thereby providing a connection for superficial infection of the face to reach intracranial structures. Infection in the cavernous sinus can lead to meningitis or thrombosis. A thrombosis here will cause an increase
in pressure and compress these nerves leading to problems with eye movements and sensation over the face.
what are the ventricles of the brain?
There are central cavities within the brain that are filled with cerebrospinal fluid (CSF)
They are continuous with the subarachnoid space meaning the CSF can surround the brain and spinal cord. In this way, the
brain is submerged in a thin layer of CSF which provides a degree of physical protection, and
mechanism for transfer of certain substances in and out of the brain tissue.
where is CSF produced?
lateral ventricles by choroid plexus
how does CSF flow from the lateral ventricles into the third ventricle?
via the interventricular foramen
what connects the third and fourth ventricle?
cerebral aqueduct
how does CSF leave the ventricular system?
- Inferiorly via central canal to fill subarachnoid space around spinal chord
- Posteriorly via apperture of magendie and lateral apertures of Luschka to enter subarachnoid space
how is CSF recycled back into the bloodstream?
arachnoid granulations
- Using your knowledge of the functional areas of the brain and their blood supply, what
might be the likely consequence of a blockage of the following arteries?
a. Left middle cerebral artery.
b. Right posterior cerebral artery.
c. Basilar artery.
a - upper limb, facial weakness
b - left visual field defect
and cerebellar disfunction
c- numerous cranial nerves, ascending descending - locked in syndrome
Which lobes of the brain are located superior, inferior and deep to the lateral sulcus?
superior = parietal and frontal
inferior = temporal
deep = insula
What is the name of the sheet of fibrous material that divides the two hemispheres of the brain in the longitudinal fissure? What is this tissue part of?
falx cerebri
made of two layers of dura mater
What are the names of the large vessels that drain venous blood from the brain to the internal jugular veins?
dural venous sinouses.
(sigmoid –> internal jugular)
- Between which two layers of the meninges would you find CSF?
arachnoid and pia mater (subarachnoid space)
What are the three routes that CSF can take out of the fourth ventricle?
central canal, median aperture, lateral aperture.
Where is CSF produced and where is it reabsorbed?
choroid plexus in lateral ventricles.
reabsorbed by arachnoid granulations
Which arteries supply the following areas of the brain?
a. Wernicke’s area.
b. Broca’s area.
c. Primary auditory cortex.
d. Part of the somatosensory cortex receiving sensory information from the arms
and face.
e. Part of the motor cortex that controls the feet and toes.
a. MCA
b. MCA
c. MCA
d. MCA
e. ACA
What layers of tissue must be penetrated during surgery to reach the surface of the brain
from outside the head?
skin, fascia, aponeurosis of scalp muscles, fascia, periosteum, skull, dura mater, arachnoid materm pia mater
What type of bleed between the layers of the meninges is likely in the following cases?
a. Young adult patient who suffers a lateral head injury after falling off a bicycle without a helmet. They remain conscious for 12 hours after the injury, before becoming profoundly unconscious.
Extradural heamorrage
What type of bleed between the layers of the meninges is likely in the following cases?
b. Elderly patient with a history of heavy alcohol use who stumbles at home and bangs their head. They retain consciousness, but the family notices they are
becoming gradually more confused over the next two weeks.
subdural heamatoma
What type of bleed between the layers of the meninges is likely in the following cases?
c. A middle-aged patient with a known cerebral aneurysm who suffers a very severe,
sudden-onset, ‘worst-ever’ headache and becomes photophobic with vomiting
and drowsiness.
Subarachnoid haemorrhage
The base of the skull is formed from several individual bones joined by fibrous joints known as ?
sutures
label the three cranial fossa of th ebase of the skull
What passes thorugh the hols of the cribiform plat of the ethmoid bone?
olfactory nerves
what three bones make up the anterior cranial fossa?
Frontal bone - (orbital part)
Ethmoid bone - (the cribiform plate and cristal galli)
Sphenoid bone - (the lesser wings of)
what two bones make up the middle cranial fossa?
Temporal bone - Petrous and squamous parts
Sphenoid bone - Greater wing and body
- pituitary fossa / sella tucica located in middle cranial fossa
Label the foramina of the cranial fossa.
What does the optic canal transmit?
the optic nerve into the bony orbit.
what does the superior orbital fissure transmit?
transmits several nerves that provide motor innervation
(oculomotor, trochlear and abducens nerves) and sensation (ophthalmic branch of the trigeminal nerve) to the orbital region.
3456
whay does the foramen rotundum transmit?
the maxillary branch of the trigeminal nerve.
what does the foramen ovale transmit?
the mandibular branch of the trigeminal nerve.
what does the foramen lacerum transmit?
the internal carotid artery exits the carotid canal through this
foramen to enter the skull.
what does the foramen spinosum transmit?
middle meningeal artery
what makes up the posterior cranial fossa?
ocipital bone
petrous part of temporal bone
what does the internal auditory meautus transmit?
the vestibulocochlear and facial nerves into the
inner ear cavity.
what does the jugular foramen transmit?
the glossopharyngeal, vagus and accessory nerves, and the
internal jugular vein.
VAG
what does the hyposglossal canal transmit?
the hypoglossal nerve
what does the foramen magnum transmit?
central nervous system fibres to leave the skull and become the spinal cord.
what is the weakest part of the skull?
the Pterion - shallow depression where four bones (frontal, parietal, temporal, sphenoid) of the skull converge
-where the middle meningeal artery lies ∴ traumatic injusry here likely extradural haemorrhage
what bones make up the bony orbits?
the larger frontal, sphenoid, zygomatic and maxillary bones, and the smaller ethmoid and lacrimal bones.
what nerves run through the orbits?
II = vision
III IV XI = muscles
V (opthalmic division) = sensation to eye and forehead
- Elevation –
- Depression –
- Adduction –
- Abduction –
- Extorsion –
- Intorsion –
- Elevation – to look up.
- Depression – to look down.
- Adduction – to look medially.
- Abduction – to look laterally.
- Extorsion – to rotate the eye, so the top of the eye rotates laterally.
- Intorsion – to rotate the eye, so the top of the eye rotates medially.
Both eyes do not necessarily perform the same movement when you change where you look.
For example, to look to your left with both eyes, your left eye needs to abduct, but your right eye
will need to adduct. This is known as conjugate eye movements.
Muscle - nerve supply - action to eye - findings if non-functional
Muscle - nerve supply - action to eye - findings if non-functional
Muscle - nerve supply - action to eye - findings if non-functional
Muscle - nerve supply - action to eye - findings if non-functional
Muscle - nerve supply - action to eye - findings if non-functional
Muscle - nerve supply - action to eye - findings if non-functional
Which Extraocular muscles are supplied by CNXI, CNIV and CNIII?
Lateral Rectus = CN6
Superior Oblique = CN4
The rest = CN3
LR6SO4
label the seven extraorbital muscles
Superior view - so which one cant be seen?
Inferior Oblique underneath
label the extraocular muscles
what is the main function of the superior and inferior rectus?
what are their additional actions?
mainly: elevate and depress the eye.
additionally: intorsion and extorision = econdary effects caused by the angle at which these two muscles pull on the
eye.
When looking at the orbits from above, if you draw a line through the centre of both orbits (which represents the angle at which these muscles pull on the eye) you’ll notice these two lines are not parallel and they do not point directly forwards. They diverge off to each side. However, the eye is normally angled to point directly forwards. This means that when the superior or inferior recti act on the eye, they are not only pulling it upwards or downwards, but they are also causing it to intort or extort and adduct.
The [a] muscle originates at the back of the eye but passes through a fibrous sling called the [b], which is located in the [c] corner of the orbit. The muscle then inserts onto the top of the eye, so it’s action will pull the top of the eye medially,
causing it to rotate. The top of the eye rotating inwards is called [d].
The superior oblique muscle originates at the back of the eye but passes through a fibrous sling called the trochlea, which is located in the superior and medial corner of the orbit. The muscle then inserts onto the top of the eye, so it’s action will pull the top of the eye medially, causing it to rotate. The top of the eye rotating inwards is called intorsion.
The [a] muscle originates from the medial orbital wall and inserts on the bottom of the eye. Its action will pull the bottom of the eye medially, also causing it to rotate, but in
the opposite direction. With the top of the eye rotating outwards, this is called [b].
INferior oblique
extorsion
The reason that the eye needs the oblique muscles to be able to intort and extort is to counter the secondary effects of extorsion and intorsion caused by the [?] muscles respectively. This helps maintain steady vision when looking up or down.
inferior and superior recti
The eye is responsible for providing us with sight. As light enters the eye, it is focused to [a] onto the [b] where it is detected by specialised cells called [c]. These cells
generate nerve impulses which are transmitted along the [d] towards the [e] in the occipital lobe.
The eye is responsible for providing us with sight. As light enters the eye, it is focused to converge onto the retina where it is detected by specialised cells (rods and cones). These cells generate nerve impulses which are transmitted along the optic nerve and optic tracts towards the primary visual cortex in the occipital lobe.
To achieve good vision, the eye must be able to focus light to varying amounts depending on how far away the object is that is being visualised. This is called ?
accomidation
accomidation in the eye is acheived by adjusting ?
the thickness of the lens
thicker = greater refraction ∴ near sight
thinner = less refraction ∴ far sight
what muscles are responsible for adjusting thr thickness of the eye lens?
innervation?
ciliary muscles
Oculomotor nerve (CNIII).
Parasympathetic (Autonomic)
which muscle is responsible fot pupillary constriction?
innervation?
Constrictor Pupilae = circular muscle in iris
Oculomotor never (CNIII)
Parasympathetic (autonomic)
which muscle is responsible for dilating the pupils?
innervation?
dilator pupillae = radial muscle in iris
Sympathetic fibres from Sypathetic Chain (autonomic)
What are the afferent and efferent nerves of the pupillary light reflex?
afferent (sensory) = optic nerve
- information about light from retina to midbrain
⇩
> synapses with Edinger-Westphal nucleus<
⇩
efferent (motor) = oculomotor nerve
- initiates dilator/constrictor pupilae muscles
When a light is shone in one eye of a healthy patient, both pupils will constrict.
The constriction of the pupil which is having a light shone into it is called the [a], and the constriction of the other pupil is called the [b].
The reason that the other pupil constricts as well is because there is a connection between the right and left [c] such that if one side is activated, then both sides are activated.
When a light is shone in one eye of a healthy patient, both pupils will constrict.
The constriction of the pupil which is having a light shone into it is called the direct pupillary response, and the constriction of the other pupil is called the consensual pupillary response.
The reason that the other pupil constricts as well is because there is a connection between the right and left Edinger-Wesphal nuclei such that if one side is activated, then both sides are activated.
why does our nose run when we cry?
tears flow across the surface of the eye into the lacrimal ducts, then into the nasal cavity via the nasolacrimal duct.
secretomotor innervation of the lacrimal gland?
Facial Nerve (CN VII) - parasympathetic
Explain the clinical findings of oculomotor nerve palsy
Affected eye = down-and-out (depressed and abducted)
-This is because the lateral rectus and superior oblique muscles are unopposed so pull the eye into that position at rest.
Affected eye = pupil dilation
-loss of parasympathetic nerve supply to the constrictor pupillae, leaving dilator pupillae unopposed.
Affected eye - eyelid droop
- loss of motor nerve supply to levator palpebrae superioris, the eyelid will droop (ptosis)
Additionally, on asking the patient to look left and
right, the affected side will be unable to adduct.
What would the clinical finding be with Abducens nerve palsy?
affected eye unable to abducts
-lateral rectus muscle no longer working
-lateral rectus overpowered by medial rectus
stabismus/ “squint”
how would a clinician test the function of the superior oblique muscle?
a clinician observes if the patient can depress an adducted eye.
what makes up the outer ear?
pinna
ear canal
tympanic membrane
what are the three ossicles?
malleus (hammer)
☟
incus (anvil)
☟
stapes (stirrup) (☞ oval window)
The inferior opening of the auditory tube is in the posterior and inferior part of the ?.
nasal cavity
connection vital to maintain equal air pressure
what are the muscles of the middle ear?
function and innervation?
tensor tympani
- onto malleus. contraction = inreases tensions in the TM reducing vibration
- CN V - mandibular branch
stapedius
- onto stapes. contraction dampens vibration on stapes
- CN VII
Cochlea – as sound waves and vibrations travel through fluid within the cochlea, they are converted into [a] which are passed via the [b] to the auditory cortex. This allows us to perceive sound.
The sound waves first enter the cochlea via the [c] (which the stapes is in contact with). The [d] is located nearby and bulges in and out to allow the fluid within the cochlea to move.
Cochlea – as sound waves and vibrations travel through fluid within the cochlea, they are converted into electrical impulses which are passed via the cochlear nerve to the auditory cortex. This allows us to perceive sound.
The sound waves first enter the cochlea via the oval window (which the stapes is in contact with). The round window is located nearby and bulges in and out to allow the fluid within the cochlea to move.
what three components make up the vestibular system?
semicircular canals (x3) = allow us to percieve movement
utricle and saccule = allow us to percieve linear acceleration
what does the oculocephalic reflex allow for?
the ability to maintain fixed gaze whilst moving out head.
Vesibulocochlear nerve carries info to the pons
Here, there are connections to other brainstem nuclei of the oculomotor, trochlear and abducens nerves which control eye movements.
List the cranial nerves which pass through the following foramina:
a. Superior orbital fissure
b. Jugular foramen
c. Internal acoustic meatus
a. III, IV, V1, VI
b. IX X XI
c. VII, VIII
what are the two parts of the midbrain?
tectum (dorsal)
tegmentum (ventral)
what is the superior colliculi involved in?
in tectum
regulating eyemovements and reflexes associated with visual stimuli, such as turning or moving the head quickly when something quickly enters our field of vision.
found in tectum
what is the inferior colliculi involved in?
sound location, pitch discrimination and reflexes associated with auditory
stimuli, such as turning our head on hearing a loud noise.
found in tectum
where is the substantia nigra found and what is it important for?
found in tegmentum of midbrain,
important for motor control by producing dopamine
where are the cerebral peduncles found and what are they?
found in tegmentum of midbrain on most ventral surface.
- large white matter bundles that connect mibrain to thalami and red nuclei (support motor control of limbs)
which nuclei are found in the midbrain?
oculomotor (CNIII), trochlear (CN IV) and Edinger-Westphal nuclei (involved in the pupillary light reflex).
What artery llies on the ventral surface of the pons?
basilar artery
what lies on the dorsal survace of the pons?
middle cerebellar peduncles (large white matetr connections to cerebellum)
What is the groove on the ventral surface of the medulla called? what does it separate?
Anterior Median Fissure.
separates the two medullary pyramids.
what runs through the medullary pyramids?
corticospinal tracts (essential motor tracts)
what runs lateral to the medullary pyramids?
medullary olives
what pathway of nerves runs in the dorsal part of the medulla?
through what nerves bundles?
DCML - dorsal column medial lemniscus
runs through two nerve bundle pairs: fasciculus
gracilis and fasciculus cuneatus.
which nuclei are found in the medulla?
glossopharyngeal (CN IX), vagus (CN X) and hypoglossal (CN XII) nerves.
The medulla also contains vital centres responsible for regulating respiration, heart rate and blood pressure, and initiating vomiting.
how many cranial nerves are there?
12 pairs
all cranial nerves leave their respective point of origin from the CNS anteriorly except which nerve?
trochlear (CN IV) which leave the midbrain posteriorly
which CN are sensory only?
I, II, VIII
which CNs are motor only?
III, IV, VI, XI, XII
which CNs are both motor and sensory?
V, VII, IX, X
which CNs have parasympathetic innervation
III VII, IX, X
what muscles does V3 provide motor innervation to?
- Tensor tympani
- temporalis
- masseter
- medial pterygoid
- lateral pterygoid
middle ear = msucles of mastication
123456 imprtant to know (and deduce others)
The facial nerve takes an unusual route out of the skull. It first passes through the [a] alongside the vestibulocochlear nerve (CN VIII). Shortly after this, it gives off a
branch which supplies [b] function to the [c]
[a] internal auditory meautus
[b] parasympathetic secretomotor
[c] lacrimal
As it progresses through the middle ear cavity, the facial nerve gives off a branch to the
[a] and another branch known as the ‘[b]’. This nerve supplies taste sensation to the [c] of the tongue and [d] function to the [e]. The facial nerve then leaves the temporal bone of the skull via the [f] which is located between the [g] processes of the temporal bone, hence the name.
As it progresses through the middle ear cavity, the facial nerve gives off a branch to the
stapedius muscle and another branch known as the ‘chorda tympani’. This nerve supplies taste sensation to the anterior 2/3 of the tongue and parasympathetic secretomotor function to the submandibular and sublingual salivary glands. The facial nerve then leaves the temporal bone of the skull via the stylomastoid foramen which is located between the styloid and mastoid processes of the temporal bone, hence the name.
After exiting the skull, the facial nerve gives of a small branch which carries sensory information from the [a] and motor supply to [b]. The main body of the facial nerve then enters
the substance of the [c] (which it does not innervate), and within it, divides
into [d] branches which spread out across the face to supply the muscles of facial expression.
After exiting the skull, it gives of a small branch which carries sensory information from the ear and motor supply to some muscles of the scalp. The main body of the facial nerve then enters the substance of the parotid salivary gland (which it does not innervate), and within it, divides into five branches which spread out across the face to supply the muscles of facial expression.
what are the five branches of the facial nerve that supply the muscles of facial expression?
temporal, zygomatic, buccal, marginal mandibular
and cervical branches.
To Zanzibar By Motor Car
The glossopharyngeal nerve has numerous functions:
- It supplies motor function to one muscle, [a], which assists with facilitating swallowing.
- It carries general sensation from the [b]
- Carries both general and taste sensation from the [c]
- It provides parasympathetic secretomotor
supply to the [d]
- it carries unconscious sensory information
from the [e] towards the medulla.
The glossopharyngeal nerve has numerous functions:
- It supplies motor function to one muscle, [stylopharyngeus], which assists with facilitating swallowing.
- It carries general sensation from the [middle ear, auditory tube, majority of pharynx]
- Carries both general and taste sensation from the [posterior 1/3 of tongue]
- It provides parasympathetic secretomotor
supply to the [parotid salviary gland]
- it carries unconscious sensory information
from the [carotid chemoreceptors and baroreceptors] towards the medulla.
Light is detected by the [a] within the eye and impulses are passed via the [b] then
[c]and finally the [d] before reaching the [e] in theoccipital lobe.
The fibres divide and cross over in a complex way.
[a] retina
[b] optic nerve
[c] optic tracts
[d] optic radiations
[e] primary visual cortex
each visual field is divided into:?
temporal (lateral) and nasal (medial) field
It is vital to understand that light entering from
the lateral half of our visual field is received by the medial (nasal) part of the retina, and vice
versa. So, the nasal retina provides our temporal visual field, and the temporal retina provides
our nasal visual field.
At the optic chiasm, visual information from the temporal visual fields (nasal
retinas) from each eye [?]
At the optic chiasm, visual information from the temporal visual fields (nasal
retinas) from each eye cross over, such that information about the temporal vision from the left eye now travels through the right side of the brain, and vice versa.
After the optic chiasm, the visual information travels along the [a]. When the tracts
reach the [b], the majority of fibres synapse in the [c]. After they synapse, the fibres carrying the visual information towards the primary visual cortex divide into a superior and inferior pathway on each side, known as [d]
After the optic chiasm, the visual information travels along the optic tracts. When the tracts
reach the thalamus, the majority of fibres synapse in the lateral geniculate nucleus. After they
synapse, the fibres carrying the visual information towards the primary visual cortex divide into
a superior and inferior pathway on each side, known as optic radiations.
what are the two optic radiations?
parietal and temporal (meyers) radiation
The visual information within the parietal radiations is received from the ?
and therefore constitures which field of vision?
The visual information within the parietal radiations is that which is received in the superior aspects of the retinas, and therefore constitutes the inferior fields of vision.
Conversely, the
information in the temporal radiation is from the inferior retinas, which is therefore from the
superior parts of our field of vision.
what would this be caused by?
damage to an optic nerve
what would this be caused by?
damage to optic chiasm (The fibres that cross at the optic chiasm are carrying visual
information from the nasal retinas, and therefore information about the temporal visual
fields.)
what would this be caused by?
damage to an optic tract
If left optic tract is damaged, information from the left temporal retina and right nasal retina is
lost, meaning the left nasal visual field and the right temporal visual field are lost. This would
mean the patient has lost the right side of their vision in both eyes, so would be termed a
right homonymous hemianopia.
what would thisbe caused by?
damage to either parietal or temporal optic radiation. (between the lateral geniculate nucleus)
If the left parietal optic radiation is
damaged, information from the left superior temporal retina and right superior nasal retina is lost, meaning the left inferior nasal visual field and the right inferior temporal visual field are
lost. This would mean the patient has lost the bottom-right corner of their vision in both eyes,
so would be termed a right inferior homonymous hemianopia.
A person with which CN damage will complain of double vision as they look down (e.g. when walking down a flight of stairs)?
CN IV (SO)
one eye looking down and in. one eye unable to
Which structure divides the midbrain into the tectum and tegmentum?
cerebral aqueduct
which CNs contain parasympathetic fibres?
occulomotor
facial
glossopharyngeal
vagus
enlargement of which structure may cause a bitemporal hemianopia?
pituitary gland
where are the olfactory bulbs found?
superior surface of cribifrom plate, either side of crista galli.
which nerves are responsible for the movements of eye and diameter of the pupils?
oculomotor, trochlear and abudcens
which of the branches of the trigmeminal nerve is motor and sensory?
V3 - mandibular.
sensory - inferior 1/3 of face.
senesory - anterior 2/3 of tongue, mandibular and gums.
motor - 5 chewing muscles and tensor tympani
which nerve carries information of the special senses hearing and equilibrium
(balance) from the inner ear?
vestibulocochlear CNVIII
which nerve provide taste sensation to the posterior 1/3 of the tongue?
glossopharyngeal
which nerve provides taste sensation to the anterior 2/3 of the tongue?
Facial VII
Which nerve provides motor and sensory information to the larynx?
vagus
which nerve carries parasympathetic supply to thoracic and abdominal organs?
vagus
which nerve supplies motor innervarion to the soft palate, palatine folds and pharyngeal constrictors?
vagus
which nerve carries general senstaion from ear canal and pinnna?
vagus
which nerve carries taste sensation from the epiglottis of the larynx?
vagus
where to the accessory nerve originate from? which holes does it ener/leave through?
what muscles does it innervate?
c1-c5
enters through foramen magum
leaves through jugular foramen
supplie sternocleidomastois and trapezius
which nerve supplies motor innervation to the intrinsic and extrinsic muscles of the tongue?
(except which muscle which is supplied by?)
thought which foramen does it leave though
hypoglossus
(all muscles of tongue except palatoglossus = vagus)
leaves through hypoglossal canal
how would you test the function of CN1
has smell changed.
identify smells
how would you test the function of CNII
peripheral vision accomodation to near and far objects
how would you test the function of CNIII
eyes follow finger
alongside CN IV and CN VI
how would you test the function of CNV
Sensory: Firstly, sensation is tested by simply ensuring the patient can feel a brush of cotton wool
against their skin in the three regions of the face (forehead, cheek, jaw) on both sides.
Sensation may be further tested by ensuring the patient is able to tell the difference
between sharp and crude touch, or by testing the blink reflex when the cornea of the eye
is touched.
Motor function is tested by palpating a patient’s jaw muscles as they clench
their teeth or asking the patient to forcibly open their mouth against resistance.
how would you test the function of CNVII
facial movements eg rasing eyebrow
how would you test the function of CNVIII
cover one ear and whisper
how would you test the function of CNIX
gag reflex
how would you test the function of CNX
cough and swallowing
how would you test the function of CNXI
shrug and turn head
how would you test the function of CNXII
deviation of tongue when stuck out
the cerebellum is connected to the brainstem via three pairs of?
cerebellar peduncles
the cerebellum is divided by a midline structre called?
the vermis
what are the “gyri” of the cerebellum called?
folia
Spinocerebellum:
anatomical part?
Primary INput?
Cerebella peduncle?
Function?
cerebrocerebellum.
anatomical part?
Primary INput?
Cerebella peduncle?
Function?
vestibulocerebellum.
anatomical part?
Primary INput?
Cerebella peduncle?
Function?
what atre the three routes of blood supply to the cerebellum, and why can a blockage in any three cause more than just cerebellar dysfunction?
SCA, AICA, PICA
- all three supply part of the brainstem too
what are the symptoms of cerebllar dysfunction?
VANISHED
Vertigo
Ataxia
Nystagmus
Intention tremor
Slurred speech
Hypotonia
Exagerated Past-pointing
Dysdiadochokinesia (DDK)
function of corpus callosum?
group of commisural fibres that connect left and right hemispheres.
function of the thalamus?
relay system for most functions of the brains
function of hypothalamus?
homeostasis.
control of endocrine functions of body and ANS
function of pituitary gland?
hormone secretion, under control of hypothalmus.
where does the pititary gland sit?
pituitary fossa/ sella turcica in sphenoid bone
function of pineal gland?
secretes melatonin - sleep/wake cycle
structures that make up the limbic system?
Fornix, mammillary bodies, amygdala, hippocampus, cingulate gyrus and sulcus
the basal ganglia are a group of [?] of the brain that contribute to [?x3]
deep nuclei
coordination, control/inhibition of motor function
the. basal ganglia is spread throughout the..?
Cerebrum, diencephalon, midbrain
what are the 5 nucleus of the basal ganglia?
- Caudate (c-shaped)
- Globus Pallidus (triangular)
- Putamen (oval)
- Substantia nigra (black)
- Substhalmic (small)
what nuclei makeup the lentiform nucleus?
putamen and globus pallidus
what nuclei make up the striatum?
caudate and lentiform
what structures are anatomically a part of the basal ganglia, but are not involved in motor control function of basal ganglia? (involved in LIMBIC instead)
Nucleus accumbens (reward)
Amygdala (memory emotin response)
The internal capsule forms part of the route of the majority of what axons?
sensory and motor axonms travelling to and from the cortex.
the fibres within thr internal capsule are examples of?
projection fibres - connect cortex to deeper structures
damage to the internal capsule (stroke) can causE?
significant controlateral motor and sensory dysfunction
the axons that pass from the internal capsule to the cortex form the?
corona radiata.
Parkinson’s disease is caused by?
degeneration of dopamine producing neurons of the substantia nigra = reduction of passage of impulses wiwthing basal ganglia.
impaired initiation and inhibition of movement
where does huntington’s disease mostly affect within the basal ganglia
striatum –> chorea
chorea= sudden jerky incrontrollable movemens of face arms and legs
which nerve?
occulomotor
which nerve?
trigeminal
which nerve?
trigeminal
which nerve?
abducens
which nerve?
glossopharyngeal
which nerve?
hypoglossal
how many differences between autonomic and somatic nervous system?
what are they?
THREE.
1. somatic = voluntary, automonic = involunatry
2. somatic do not synapse after CNS (one neuron chain). autonomic = synapse after CNS (two-neuron chain)
3. somatic - skeletal muscle, always stims. autonomic = smooth, cardiac, glands. stim/inhibit
Parasympathetic innervation is predominantly via what?
but also???
predominantly cranial nerves (III, VII, IX, X)
but also sacral outflow (S1, S2) to oelvic organs (sex)
Sumpathetic innervation is predominantly via what?
but also?
predominantly sympathetic chain (C8 - T1)
are autonomic nerves myelinated or unmyelinated?
myelinated preglangion
unmyelinated postganglion
what carries preganglionic sympathetic fibers to the sympathetic chain, and what contains postganglionic sympathetic fibers rejoining the spinal nerve. (Both of these branches contain afferent fibers as well.)
The white ramus communicans carries pre ganglionic sympathetic fibers to the sympathetic chain.
the gray ramus contains postganglionic sympathetic fibers rejoining the spinal nerve. Both of these branches contain afferent fibers as well.
how is it that digestion can take place without parasympathetic input?
the enteric nervous system.
functions independently
what is the primary neurotransmitter of the enteric nervous system?
serotonin
what are the receptors of the sympathetic and parasymapthetic nervous system?
Sympathetic
- pregang = nicotinic
- postgang = Adrenergic
Parasympathetic
- pregang = nicotinic
- postgang = muscarinic
what receptors are present in the carotid body?
Baroreceptors (stretch/BP)
Chemreceptors (O2)
–>to brainstem…(+/-) para/symp
what is the primary neurotransmitter of the sympathetic nervous system?
Preganglion = ACh
Postganglion = NE
what is the primary neurotransmitter of the parasympathetic nervous system?
preganglion = ACh
postganglion = ACh
medial geniculate nucelus = (inferior colliculi)
lateral geniculate nucleus = (superior colliculi)
medail = aud
lateral = vis
4 functionss of the spinal column
- protect the spinal chord
- support the head and torso
- attatchments for muscles and tibs
- site of haematopoeisis
how many vertebrae are there?
33 vertebrae:
- 7 cervical
- 12 thoracic
- 5 lumbar
- 5 sacral
- 4 coccygeal
what are the distinct types of curvatures of the vertebral column?
cervical lordosis (inwards)
thoracic kyphosis (outwards)
lumbar lordosis
scoliosis = lateral curvature
which part of the vertebrae are muscles attatched to?
transverse processes
(cervical - vertebral arteries, thoracic = ribs)
what type of joint are the articular processes?
synovial articulations called facet joints
where is the “atlas”?
C1 - artiulates directly with occipital bone of skull, allows us to nod our heads.
why is the vertebral body of the atlas different?
no body or spinous process
how does the axis differ from other vertebrae?
C2 - has a body that prodtrudes upwards = odontoid process = takes the place of the bodyof the atlas aboves it so that the atlas can spin around the axis.
atlanto-axial joint = pivot joint
describe the Vertebral body, spinous process and transverse processes of the Cervical Vertebrae (C3-C7)
Vertebral body - small
Spinous process = bifid (except C7)
Travsverse processes = contain transverse foramen
describe the Vertebral body, spinous process and transverse processes of the Thoracic Vertebrae
Vertebral body - medium, heart shaped
Spinous process - long, sharp, down-sloping
Transverse processes - contain articulation for the ribs
describe the Vertebral body, spinous process and transverse processes of the Lumbar Vertebrae
Vertebral body - very large
Spinous process - large, short, rectangular
Transverse processes - long, flat, directed laterally
what are the primary movements of the different vertebrae?
Atlas / Axis - rotation
Cervical - Flexion, extension, lateral flexion
Thoracic - rotation
Lumbar - Flexion, extension, lateral flexion
Sacral and coccyx - none
what are the invertebral discs made from?
Fibrocartilaginous:
central gelatinous core = nucleus pulposus
rings of collagen = annulus fibrosus
what serparates the invertebral discs from the nieghbouring vertebrae?
thin layer of hyalin cartilage
what makes up the layers of a secondary cartilaginous joint, like that of the invertebral discs and vertebrae?
bone
hyaline cartilage
fibrocartilage
hyaline cartilage
bone
label the spinal ligaments of the vertebral column
What do the paraspinal muscles make up?
the erector spinae
what does this T2 weighted MRI show?
disc herniation - repetitive compression of the invertebral discs → weakining of annulus fibrosus→posterior herniation of nucleus palposus→narrowing intervertebral foramina→compress spinal nerve → neurological defecot/muscle weakness
at what level does the spinal chord terminate?
L1/L2
at what level must a lumbar puncture be performed?
below the level of L2
at this level, the nerves off the cauda equina are simply pushed out the the way of the needed rather than being damaged by it.
what is the L4/L5 space in line with?
intercristal plane
what layers does a needle go through when preforming a lumbar puncture?
Skin.
Subcutaneous tissue.
Supraspinous ligament.
Interspinous ligament.
Ligamentum flavum. - pops
Epidural space.
Dura. - pops
Arachnoid. = CSF
where do spinal nerves leave in the vertebral column?
C1–7 nerves exit above their respective vertebrae, and all other nerves exit below their corresponding vertebrae
there is an extra spinal nerve -
and only one ? nerve
C8 spinal nerve (below C7)
Only one Co1
31 pairs of spinal nerves in total
At the level [?], the spinal chord tapers off into the [?] and terminates. The {?] and [?] contine down to the sacrum. The [?] thickens to form a thin strand of fibrous tissue called the [?] which continues all the way to the coccyx where is helps tether the spinal chord in position
L1/L2 junction
conus medullaris
dura and arachnoid
pia mater
filum terminale
what is the cauda equina?
“horses tail” all the spinal nerves that are yet to leave after the spinal chord terminates are given off all together.
Dorsal root carries what kind of fibres?
Sensory into the spinal chord
Ventral root carries what kind of fibres?
Motor fibres out of the spinal chord
sympathetic fibres leave the cord via which root?
ventral root.
what are the ventral rami renames in the ribs?
intercostal nerves
in the sensory pathway, what are the first order neurons?
neurons from the receptor to the CNS (spinal cord or brainstem)
cell bodies in dorsal root ganglion
in the ascending sensory pathway, what is the second order neurons?
from CNS (spinal cord/brainstem) to thalamus
in the asceding sensory pathways, what are third order neurons?
from thalamus to somatosensory cortex
in the descending motor pathways, what are the first order neurons?
UMN - from motor cortex to ventral horn of spinal cord
in the desceniding motor pathway, what are the second order neurons?
LMN - from spinal cord to target muscle
At some point along their path, a neurone in most of the ascending or descending tracts willcross over to the contralateral side. This crossing is known as the decussation. Different tracts decussate at different points.
which spinal tracts DO NOT DECCUSSATE?
Vestibulospinal and Reticulospinal tracts
Posterior SpinoCerebellar
what are the spinal tracts?
nundles of axons organised into columns in the peripheral white matter of the spinal cord.
What information do the Dorsal Columns Medial Leminiscus carry?
sensory information about fine touch, two-point discrimination and proprioception.
where do the dorsal column medial lemniscus deccussate?
the Medulla.
after synapsing at thier nuclei in medulla.
deccussat and contine to thalamus contralaterally
where do the DCML tracts synapse?
- at the medulla - gracile and cuneate nuclei
- at the thalamus - conyinue to primart somatosensory cortex
what are the two tracts of the DCML and where do they carry information from?
Fasciculus gracilis -medial, lower limbs
Fasciculius cuneatus - lateral, upper limbs
what information does the spinothalamic tract carry?
crude touch, pain and temperature
where does the spinothalamic tract deccussate?
in the spinal cord. usually after travelling up one or two vertebral levels
where does the spinothalamic tract synapse?
- within dorsal horn
- in the thalamus - continue via intenal capsule via primary somatosensory cortex
what inforomation do the lateral corticospinal tracts carry?
motor impulses.
where do the lateral corticospinal tracts deccussate?
the medulla
-at the level of the medullary pyramids - continue contralaterally in spinal cord
where do the lateral corticospinal tracts synapse?
- in the ventral horn
UMN →motor cortex → internal capsule → medulla DECCUSSATES → spinal cord → ventral horn SYNAPSE →LMN
what do the anterior and posterior spinocerebellar tract carry?
unconscious proprioception to the cerebellum
where does the anterior spinocerebellar tract decussate?
1 x level of cord entry
1x as soon as it enters cerebellar
∴ipsilateral
where does the posterior spinocerebellar trac decussate?
does not decussate
ipsilateral in cerebellum
What would the finding be is patient suffers damage to the right hand spinal cord?
Right: loss of DCML and Corticospinal
Left: loss of Spinothalmic
