Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Danielle's MD1 > Neuroscience > Flashcards

Neuroscience Flashcards

1
Q

What uptake pathway does cocaine block?

A
  • neuronal uptake pathway (high affinity pathway)
  • blocks uptake of NA, DA and 5-HT
  • also blocks NA channels (local anaesthetic drugs)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Describe the effect of amphetamine on noradrenergic transmission in the CNS

A
  • displaces noradrenaline from storage vesicles
  • increased NA in synapse
  • increased response
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Describe the biosynthesis pathway of catecholamines

A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Describe the anatomical directions in the NS

A

Brain

Brainstem

Spinal cord

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Describe the structure and function of the cerebrum

A
  • 2 hemispheres separated by a longitudinal fissure
  • ridges= gyri
  • grooves= sulci
  • surface is the cortex
    • superficial layer of grey matter
    • core of white matter (many layers)
    • has pyramidal and interneurons
    • left and right cortices linked by corpus callosum
  • its the site of language, memory, emotions and self awareness
  • organised into 4 lobes
    • Frontal
    • Parietal
    • Occipital
    • Temporal
  • each sulci and gyri has a name
  • Brodmanns areas= areas that have differences in organisation
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Describe the structure and function of the cerebellum

A
  • function= motor control, refines execution of motor program, compares what you are doing to what you want to do
  • contains half of all neurons in the brain
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Describe the structure and function of the basal ganglia

A
  • located in the telencephalon
  • function= motor control, selects and initiates voluntary movements
  • forms loops with the cortex
  • damage–> Parkinsons and HD
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Describe the structure and function of the thalamus

A
  • part of the diencephalon
  • function= major sensory relay to cortex
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What are the 3 ways the thalamic subnuclei project?

A
  1. relays sensory info to specific areas in the cortex
  2. relays non-sensory info from cortex and basal ganglia to specific areas of the cortex
  3. project globally to cortex (arousal, sleep)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Describe the structure and function of the hypothalamus

A
  • Part of the diencephalon
  • function= homeostasis and controls the pituitary
    • homeostasis of: temp, blood vol and P, ion concentration, Ph, O2 and glucose)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What are some general functions of the brainstem?

A
  • controls
    • facial muscles
    • sensation from face and head
    • cardiorespiratory control
    • arousal, sleep/wake cycle
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Describe the basic anatomy of the spinal cord

A
  • inner core of grey matter
  • outer layer of white matter
  • dorsal/posterior horn–> dorsal root (sensory axons)
  • ventral/anterior horn–> ventral root (motor axons)
  • intermediate zone
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Where are the 2 important spinal cord enlargments located? and what is their significance?

A
  • enlarged and lower cervical and lumbar regions
  • to support limbs
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Where does the spinal cord terminate?

A

at L1/2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is a dorsal root ganglia?

A
  • collection of neuronal cell bodies (in this case from sensory neurons)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Describe the structure of a DRG neuron

A
  • has branches to it
    • one branch in the peripheral nerve that detects the stimulus
    • one branch enters dorsal horn via dorsal root
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Does a pheripheral nerve have sensory or motor input?

A

it has BOTH

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is a dermatome?

A
  • a region of the body innervated by a bilateral pair of DRG
  • note: dermatomes line up when you hunch over on all 4s like a quadraped
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Describe the structure and function of ventricles

A
  • = hollow centre of the brain
  • two lateral
    • divided into anterior horn, body, lateral horn, inferior horn
  • one 3rd ventricle
  • one 4th ventricle
    • where CSF flows out
  • cerebral aqueduct
    • connnects 3rd to 4th ventricle
  • full of CSF
    • made from vascular choroid plexus
    • acts as a shock absorber
  • used as a landmark in CTs and MRIs
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Describe the meningeal layers of the brain

A
  • they are the second level of defence for the brain following on from the skull
  • 3 layers
    • Dura Mater
      • thickest
      • outer layer
      • splits into 2
      • forms dural projections (flax, tentorium)
    • Arachnoid
      • fibrous
      • middle layer
      • contains arachnoid granulations that absorb CSF
    • Pia Mater
      • thinnest layer
      • inner layer
      • closely associated with the brain (stuck to it)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Describe the structure and function of the BBB

A
  • formed by endothelial cells of capillaries
  • lack pinocytic transfer function
  • have tight junctions
  • most transport is active
  • function= protects brain becuase neurons are highly sensitive to fluctuations in ion concentrations
  • the more lipid solubule a substance is the more likely it is able to cross the BBB
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What are glial cells?

Name some examples

A
  • support cells
  • e.g.
    • astrocytes
    • oligodendrocytes
    • ependymal cells
    • satellite cells of the ganglia
  • they express glutamate transports to uptake circulating neurotransmitters in the synapse
  • they are excitable (increase intracellular Ca= calcium waves) by
    • neurostransitters (e,g ATP, glut)
    • trauma
    • spontaneous
    • inflammatory mediators
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What is the function of ependymal cells?

A
  • they are low columnar or cuboidal epithelial cells that line the central canal of the spinal cord and the ventricle
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What is the function of astrocytes?

A
  • neurotransmitter uptake and degradation (passive function)
  • K+ homeostasis (passive function)
  • neuronal E supply (passive function)
  • maintenance of BBB (passive function)
  • injury response and recovery (passive function)
  • modulation of neuronal function and BF (active function)
    • inhibits neurons by calcium waves because it–> ATP release from astrocytes
    • regulates BF bc they surrround vv
    • regulate vascular tone via Ca2+ waves
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

What is the function of oligodendrocytes?

A
  • function= myelinate axons in the CNS
  • there are lots of them in the white matter
  • each one extends its processes to wrap around parts of several axons
  • NB: diff to schwann cells which meylinate single axons in the PNS
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

What is the function of Schwann cells?

A
  • myelinate axons in the PNS
  • one wraps around one axon
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

Describe the structure of peripheral nerves

A
  • contains nerve fibres
  • composed of
    • axon
    • schwann cell
    • endoneurium
    • 1 or > bundles/fasicles/nerve fibres
    • perineurium
    • epineurium
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

What cells does the term macroglial cells refer to?

A
  • astrocytes
  • oligodendrocytes
  • schwann cells
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

What is the function of satellite cells of ganglia?

A
  • support cells in ganglia
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

What is the function of microglia

A
  • immune cell
  • resembles macrophages (has phagocytic function)
  • constantly surveying CNS
  • changes rapidly in response to inflammatory or injury
    • upregulates cytokines and GFs
  • has a role in development and disease
  • prunes synapses
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

What are the 2 types of ganglia?

A

sensory ganglia

  • house the cell bodies of sensory neurons e.g. DRG

autonomic ganglia

  • house the cell bodies of post ganglionic neurons
  • both bontain cell bodies of neurons outside the CNS and satelite cells (support cells)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

List some reasons for how neurons differ to other cells

A
  • neurons are specialsed for signalling
    • morphologically distinct
      • actin, intermediate filaments, microtubules
    • electrically active
      • membrane contains Na, ATPase pumps, ion channels
    • rapid communication
    • long distance
    • specialised
  • high level of protein synthesis
  • metabolically limited
  • terminally differentiated
    • they don’t divide with age
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

What are the 3 components that make up a neurons cytoskeleton? And what are their functions.

A
  • actin
    • dynamic assembly/disassembly
    • allows shape changes and movement
    • e.g. spines and growth cones
  • intermediate filaments
    • in all processes
    • permanent
    • maintain the shape of the cell
    • changes in disease sates
  • microtubules
    • dynamic
    • composed of tubulin
    • axon transport
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

Describe 2 diseases where dopamine is involved but in different pathways

A
  • parkinsons
    • movement disorder
    • depletion of DA in basal ganglia
  • schizophrenia
    • behavioural disorder
    • changes in DA rich areas in frontal cortex, basal ganglia and temporal lobe
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

Describe the extrapyramidal motor system organisation

A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

Can a synapse be excitatory AND inhibitory?

A

No. A synapse can only be excitatory or inhibitory, not both!.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

Can a neurotransmitter be excitatory and inhibitory?

A

yes

some neurotransmitters are excitatory (glutamate) and some are inhibitory (GABA) and some are both (dopamine/serotonin) it depends on what receptor is present.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

The cranium is divided into:

A
  • Upper part of the cranium= cranial vault
  • Lower part of the cranium= cranial floor
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

Name the different sutures on the cranium

A
  • Coronal suture
    • Frontal bone and parietal bones meet
    • Anteriorly
    • In the coronal plane
  • Sagittal suture
    • In sagittal plane
    • Where the 2 parietal bones unite
  • Lambdoid suture
    • Where the occipital and parietal bones unite
    • In coronal plane
  • Pterion suture
    • H shaped suture
    • Seen in lateral view
    • Frontal, parietal, temporal and sphenoid bone unite
    • Bones are particularly thin here
    • Deep to it is the middle meningeal artery
    • Dangerous area to get a fracture here!
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

What are the 2 parts to the frontal bone?

A
  • Vertical part
    • Forms the forrid
  • Horizontal part aka orbital plate
    • Supraorbital margins (top of the eye socket) there is a 90degree angle where the rest of the frontal bone projects backwards
    • Forms the roof of the orbit which is why its called the orbital plate
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
41
Q

What are some characteristics of the Parietal bone?

A
  • Flat and rectangular
  • Moulded to the shape of the brain
  • Anteriorly unites with frontal bone at coronal suture
  • Both parietal bones meet at the sagittal suture
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
42
Q

What are some characteristics of the occipital bone?

A
  • Relatively flat and moulded to the shape of the brain
  • Has a prominent bulge posteriorly called the external occipital protuberance (EOP)
43
Q

What are some characteristics of the temporal bone?

A

Squamous part

  • Similar to the parietal bone
  • Flat, moulded to brain contour
  • Unites superiorly with the parietal bone
  • 3 processes come off it
    • Anterior projection= zygomatic process of the temporal bone
      • Articulates with the cheek bone/zygoma
      • Depressed fracture of the cheek bone refers to a fracture of the zygomatic arch and process
    • Posterior projection= Mastoid process of the temporal bone
      • Full of air cells (bone that isn’t solid but filled with air)
      • Projects inferiorly downwards
      • Gives rise to muscles in the neck e.g. sternocleidomastoid
      • Its relatively superficial
    • Styloid process
      • Deeply placed
      • Muscles associated with midline structures e.g. the tongue, pharynx
      • Sharp spike/point

Another part of the temporal bone=petrous bone

  • Only see it when the cranial vault has been removed
  • Wedge/pyramidal shaped
  • Forming part of the cranial floor
44
Q

What are some characteristics of the sphenoid bone?

A
  • Very little can be seen of it on the external aspect of the brain
  • Looks like a bat with outstretched wings
  • Has a body
    • depression in it (where the pituitary gland sits)
  • Pair of outstretched wings with a split/fissure in them called the superior orbital fissure
    • Splits the wings into a lesser part anteriorly and a larger part called the greater wing posteriorly
  • 2 legs hanging down called the Pterygoid plates
    • Involved with muscles of mastication
45
Q

Describe the 3 cranial fossa

A
  • anterior cranial fossa
    • formed by horizontal plates of frontal bones and lesser wings of sphenoid
    • also has ethmoid bone that has the cribiform plate in it
  • middle cranial fossa
    • formed by greater wings of sphenoid anteriorly and petrous part of temporal bone posteriorly
  • posterior cranial fossa
    • formed by the occipital bones
46
Q

What goes through the cribiform plate?

A
  • olfactory nerve fibres
47
Q

What is associated with the hypophysial fossa?

A
  • (its in the body of the sphenoid)
  • the pituitary gland
48
Q

What is associated with the optic canal?

A
  • optic nerve
  • opthalamic artery
49
Q

What is associated with the superior orbital fissure?

A
  • nerves to extra-ocular muslces
  • branches of the trigemnial nerve
50
Q

What is associated with the foramen rotundum

A
  • maxillary nerve
51
Q

What is associated with foramen ovale?

A
  • Mandibular nerve
52
Q

What is associated with foramen spinosum?

A
  • middle meningeal artery
53
Q

What is associated with the internal acoustic meatus?

A
  • (Hole in the petruos part of the temporal bone)
  • (‘In the step itself’)
  • Facial nerve
  • vestibulocochlear nerve
54
Q

What is associated with the jugular foramen?

A
  • (Irregularly shaped)
  • (In the split between petrus part of the temporal bone and occipital bone)
  • CNs IX,X,XI
  • internal jugular vein
55
Q

What is associated with the hypoglossal canal?

A
  • (In the occipital bone)
  • (Seen better when the skull is turned upside down on the bottom outside surface of the skull)
  • Holds the hypoglossal nerve
56
Q

What is associated with the foramen magnum?

A

the brain stem

57
Q

Describe the dural partitions/projections

A
  • Falx cerebri
    • Sickle shaped
    • Lies in the sagittal plane/in midline
    • Projects beneath the sagittal suture
    • Lodges between the right and left hemispheres but doesn’t go all of the way through
  • Tentorium cerebelli
    • Mostly Horizontal orientated (its tented)
    • Crescent shaped
    • Separates cerebral hemispheres above from cerebellum below
    • It’s a roof over the posterior cranial fossa
  • Falx cerebelli
    • Tiny
    • Seperates the cerebelli hemispheres
    • From behind
  • Diaphragm sellae
    • Roofs over the pit of the sphenoid where the pituitary sits
58
Q

What are dural venous sinuses?

A
  • Endothelial lines space containing venous blood where the outer and inner layer of dura has split
  • Collects venous blood from the brain (cerebral veins), diploe veins (drain spongy/middle table/component of skull bones), Emissary veins (from the scalp outside the skull through the outer plate of compact bone), Superior cerebral veins
59
Q

Name the dural venous sinuses

A
  • superior sagittal sinus
    • Extends from the falx cerebri anteriorly sticking up from the cribiform plate to posterior where it attaches to the internal aspect of the external occipital protubrence
    • Collects blood form the brain and some from the scalp
  • Inferior sagittal sinus
    • In the inferior aspect of the falx cerebri
  • Straight sinus
    • Where the inferior sagittal sinus gets to the point where the falx cerebri and the tentorium cerebelli and it mixes with the great cerebral vein to become straight
  • Confluence of sinuses
    • The superior sagittal sinus and straight sinus meet at the internal aspect of the EOP
  • transverse sinus
  • sigmoid sinus
    • At the edge of the middle cranial fossa (petrous part of the temporal bone) the transverse sinus then moves out in an S shaped bend =sigmoid sinus
    • then out the jugular foramen to now be called the internal jugular vein
  • Cavernous sinus
    • Pair of them
    • Sits on the lateral aspect of the body of the sphenoid
    • Receive blood from the cerebral, ophthalmic and emissory viens of the face
    • Structures that are heading for the superior orbital fissure lie underneath/through its lateral wall
60
Q

Describe the meningeal artery supply

A
  • There are many small meningeal arteries!
  • The middle meningeal artery is the largest and the most important
    • It’s a branch of the maxillary artery
    • external carotid artery–> superficial temporal artery (goes to the temple) and the posterior auricular artery and the maxillary artery
    • middle meningeal artery enters the skull through the foramen spinosum then splits into an anterior and posterior branch that grooves the internal surface
    • anterior division runs directly to the pterion
    • middle meningeal artery lies in the extra-dural space
      often tears during trauma–> bleeds quickly–>blood pulses!–>extradural haemorrhageà intracranial P rises quickly
61
Q

Describe what happens in a fall especially in the elderly in relation to blood supply

A
  • Commonly during a fall–>tearing occurs where the cerebral veins enter the superior sagittal sinus–>venous bleed into the subdural space–>blood oozes! –>clot can calcify and not be detected–> no symptoms (and can be find later)–>calcified clot can become an epileptic focus
  • cerebral veins draining into the superior sagittal sinus
62
Q

Distinguish between general anaesthetics and local anaesthetics by commenting on sites of action, mechanism of action and name some compounds

A

Site of action

  • General anaesthetics act on the brain cortex (hence depresses cortical processing of pain, loss of consciousness)
  • Local anesthetics act on peripheral nerves (therefore they regulate pain pathways)

Mechanism of action

  • General anaesthetics
    • lipid theory
      • anaesthesia is caused by volume expansion of membrane lipids and can be reveresed by pressure
    • receptor interaction theory
      • inhibition of excitatory receptors and enhancement of inhibitory receptors
  • Local anaesthetics
    • act on Na transmembrane channels
    • hydrophobic theory
      • fast
      • non use dependent (does NOT depend on firing of nerves)
      • non charged form of drug binds to channel
    • hydrophilic theory
      • slow
      • use dependent
      • non charged form crosses the membrane then reforms charged form and can bind when the channel opens
  • Examples
    • General anaesthetics
      • desflurane, sevofulrane, isoflurane
      • propofol, thiopentone
    • Local anaesthetics
      • procaine, lignocaine, bupivicaine, roprivicaine
      • tetrodotoxin, saxitoxin
63
Q

Describe the toxicity of local anaesthetics

A
  • generally safe
  • proportional to blood level
    • CVS effects
      • myocardial depression
      • depression of vasomotor centre
      • hypotension (except cocaine)
    • CNS effects
      • excitation
      • tremor
      • convulsion
      • resp arrest
  • not proportional to blood level
    • hyersensitivity/allergic rxns
64
Q

Describe the topical application of local anaesthetics

A
  • OTC
    • lozenges
    • sports gels
  • professional use only
    • eye drops for procedures
    • injections (lignocaine) for dysrhythmias
65
Q

Name some examples of general anaesthetics

A

inhaled (to maintain you under)

  • desflurane
  • sevoflurane
  • isoflurane

IV (to get you under quickly)

  • propofol
  • thiopentone

Inhaled and IV are both LIQUIDS and they both AVOID 1ST PASS METABOLISM

66
Q

Describe the toxicity/SEs of general anaesthetics

A

resp

  • impiared ventilation
  • depressed resp centre
  • obstruction of airways (retention of secretions bc of mucocillary escalator is inhibited)

cvs

  • decreased vasomotor centre function
  • depressed contractility
  • peripheral vasodilation
  • cardiac arrhythmias
  • inadequate response to fall in BP or CO
67
Q

What are some diseases that arise from failure of the neural fold to close?

A
  • spina bifida
  • ancephaly
68
Q

Describe the process of segmentation of the neural tube

A
  • rostral end of neural tube starts to swell
  • forms 3 distinct vesicles
    • prosencephalon (forebrain)
    • mesencephalon (midbrain)
    • rhombencephalon (hindbrain)
  • prosencephalon splits into
    • telencephalon
    • diencephalon
  • Rhombencelphalon splits into 7 segments the rest is spinal cord
  • Rhombencephalon splits into
    • metencephalon (pons)
    • myeloencephalon (medulla)
69
Q

What are some mature derivatives of the telencephalon?

A
  • cortex
  • basal ganglia
  • hippocampus
70
Q

What are some mature derivatives of the diencephalon?

A
  • thalamus
  • hypothalamus
71
Q

What is the function of neuroepithelium during development?

A
  • neuroepithelium covers the neural tube
  • it adds layers to generate the cortex
  • all new neurons are born at the ventricular surface which contains stem cells
72
Q

What are radial glia? and what is their purpose?

A
  • cells attached to both surface
  • they are stem cells and can produce neurons
  • they act as railway tracks
73
Q

What are some developmental disorders that affect the cortex and cause it to be malformed?

A
  • reelin mutation (one of the guide molecules to guide neurons across the layers)
  • Lissencephaly (DCX mutation)
74
Q

What is the most common cause of male autism?

A

fragile X syndrome

75
Q

Describe the development of the spinal cord

A
  • signalling molecules set up gradients that define topography
  • floor plate induces ventral horn motor neurons
  • interneurons appear just dorsal to motor neurons
  • axonal growth initially via pioneer axons
  • axon is towed by growth cone
  • growth is steered up the chemical gradient
  • refinement/pruning of synaptic connections
76
Q

Describe the establishment of the visual system

A
  • if you temporarily cover 1 eye shortly after birth in a kitten, 6 months later the eye is blind
  • everything is normal in the retina, the blindness is cortical and permament
    • the cortex is dominated by the eye that was open
  • closure at 6 weeks has no effect. therefore as long as you have the first 6 weeks of vision, closing the eye has no effect
  • therefore there is a critical period
  • BUT if both eyes are closed there is no ocular dominance column disruption therefore there is no competition for cortical space therefore they arent blind
  • the critical period for humans is 10 years!! Therefore if you interput vision during this period impairment can occur
77
Q

Distinguish between the 4 types of mechanoreceptors in glabrous skin

A
  • Meissner encode rate of force
  • Merkel encode grip force
  • Pacinian encode vibrations
  • Ruffini encode hand posture
78
Q

Describe the different receptor field sizes of the 4 different mechanoreceptors

A
79
Q

What axon fibre type are the mechanoreceptors?

A
  • A deta type
  • with large myelinated axons
  • with cell bodies in the DRG
  • note its a single long axon from the periphery to the CNS. i.e. big toe axon has to travel a long distance
80
Q

Describe what a receptor field and two point discrimination thershold is?

A
  • the size of the receptor field determines whether you can detect the number of stimuli applied
  • Left hand side graph
    • big activation of b even though it is touching all 3 receptive fields, the brain detects there is only 1 point of contact
  • right hand side graph
    • a and c repond strongly because you have put the blue point right in the middle of its field. b has a weak amount of firing because its on its very edge of its receptive field. therefore the brain thinks there are 2 points of contact being applied
81
Q

T/F. C1 spinal nerve has a sensory and motor output.

A

FALSE

C1 only has a motor output

82
Q

Briefly describe the medial lemniscal (dorsal column) pathway aka the main tactile mechanoreceptive pathway

A
  • 3 neuron sequence to reach the somatosensory cortex
  • decussation in the caudal medulla
83
Q

Briefly describe the spinothalamic tract pathway

A
  • transmits pain, temp and touch
  • as it enters the spinal cord it immediately forms a connection with interneurons
  • crosses at the level of the spinal cord then ascends
  • note: motor neurons are ventral in the spinal cord. sensory neurons are dorsal
84
Q

Where in the spinal cord are the axons that innervate distal muscles and proximal muscles?

A
  • axons that innervate Distal muscles are lateral
  • axons that innervate proximal muscles are more medial
85
Q

What is a motor pool and how is it different to a motor unit?

A
  • motor pool= all the motor neurons in the spinal cord that innervates a particular muscle.
  • motor unit= all the muscles that one motor neuron controls/innervates
86
Q

Describe the structure of a muscle spindle

A
  • specialised sensory receptorsin the belly of a muscle
  • they detect changes in length of the muscle
  • sensory fibres= group I and II afferent axons wrap around muscles and have a surrounding CT sheath
  • muscle spindles lie in parallel with the muscle
87
Q

Describe the structure of a golgi tendon organ

A
  • sensory receptor organ
  • detects changes in muscle tension/the amount of force that is being applied to the muscle
  • sensory nerve enters and interdigitates with the CT of muscle tendons
  • the golgi tendon lies in series with the muscle
88
Q

Describe what the monosynaptic stretch reflex is

A
  • aka tendon jerk reflex/deep tendon reflex
  • the most simple reflex
  • you can do it anywhere there is a tendon
  • giving a tap to the tendon gives the muscle a bit of a stretch–> activates stretch receptors/muscle spindle is lengthened–> neuronal activity enters spinal cord–> excitatory synapse at the end of the afferent fibre–> synapses with and excites motor neuron–> increaes rate of AP–> muscle contracts
  • the spindle also activates an inhibitory interneuron which inhibits the antagonist motor neuron
  • NB muscle spindles are the only sensory organ that synapses directly with motor neurons
  • muscle spindles are low threshold and therefore dont need a lot of change in activity to actiavte them
89
Q

Describe what needs to happen in this situation so the cup doesn’t fall

A
90
Q

What bones make up the orbit and its margins?

A
  • supraorbital margin
    • formed by the frontal bone
    • can see the supraorbital notch
  • infrorbital margin
    • zygomatic bone
    • maxilla
  • roof of orbit
    • frontal bone
    • lesser wing of sphenoid
  • floor
    • maxilla
    • zygomatic
    • palatine
  • lateral wall
    • zygomatic
    • greater wing of sphenoid
  • medial wall
    • maxilla
    • lacrimal bone (most commonly fractured)**​
    • ethmoid (most commonly fractured)​
    • body of sphenoid
91
Q

Describe the structure and function of the sclera

A
  • forms 5/6th of the eyeball
  • forms part of the outer coat of the eyeball
  • maintains the shape of the globe
  • offers R to internal and external forces
  • provides attachment for the EOMs
  • made of collagen organised into whirls therefore quite strong
92
Q

Describe the structure and function of the cornea?

A
  • anterior 1/6th of the eye
  • forms part of the outer coat of the eye
  • refracting component
  • avascular and transparent
  • has 5 layers
  • its collagen fibrils are uniform in diam and run parallel to each other in lamellae. each lamellae lie at angles to each other therefore it is transparent
93
Q

What is the anterior chambre angle? Describe its function, and its components

A
  • its the junction between the iris and the cornea
  • its where the aqueous humour drains out of the eye
  • key structures in there
    • cornea
    • trabecular meshwork
    • canal of schlemm
    • ciliary body
94
Q

Describe the structure and function of the uvea

A
  • its made up of the iris, choroid and ciliary body
  • lies between the sclera and the cornea
  • its the middle coat of the eye ball
  • function= provides nutrition to the eyeball
95
Q

What are some functions of the ciliary body?

A
  • formation of aqueous humour (ciliary epithelium)
  • tethers lens (ciliary processes)
  • accomodation (ciliary muscle)
96
Q

What is the aqueous humour?

A
  • its the substance made form the ciliary epithelium of the ciliary body
  • its important for maintaining the health of the lens and cornea
  • it creats the IOP
  • it passes through the pupil and drains via the anterior chambre angle into the venous supply
97
Q

Describe the process of accomodation

A
  • it involves
    • ciliary muscle
      • innernated by parasymp NS
      • important for focussing
      • circular muscle
    • zonules(ligaments) that attach between the ciliary porcesses and the lens
  • when the ciliary muscle contracts, the lens becomes fat, this takes the P off the zonules therefore you can see up close objects
  • when the ciliary muscle relaxes the lens becomes taught and thin, this increases the P on the zonules and contracts them therefore you can see far away objects
98
Q

What is presbyopia?

A
  • the loss of accomodation that occurs with age
  • caused by a reduction in the flexibility of the lens capsule and zonules
  • note: the nerves are still ok!
99
Q

What 2 muscles control the iris? (dilate and constrict the pupil)

A
  • sphincter pupillae
    • constricts the pupil
    • innervated by parasymp
    • has circular fibres so when it contracts it constricts the pupil
  • dilator pupillae
    • dilates the pupil
    • innervated by symp
    • has radial fibres so when it contracts it pulls the pupil open and dilates it
100
Q

Describe the structure and function of the choroid

A
  • underneath the retina
  • its the 3 layers of blood vessels
  • supplies nutrients to the retina
101
Q

Describe the structure of the retina

A
  • optic nerve/optic disc
    • formed by the axons of the ganglion cells as they exit the retina to pass visual info to higher cortical areas
  • fovea/foveola=small dot in the macular
    • avascular
    • high density of cones
    • no rods
  • macular=surrounds the fovea
  • posterior pole
  • orra serrata= edge of the retina and the ciliary body
102
Q

What is the lamina cribrosa?

A
  • band of dense CT that goes across the optic nerve from one side of the retina to the other
  • sieve hole that transmits nerve fibres
103
Q

Describe the blood supply to the orbit and to the retina

A

to the orbit

  • tributaries of the ophthalmic artery which is a branch of the internal carotid artery
    • central retinal artery (its the one you see when you look via an ophthalamscope)
    • ciliary arteries
      • long posterior ciliary artery
      • short posterior ciliary artery
      • anterior ciliary artery

to the retina

  • dual blood supply
    • central retinal artery
      • supplies the inner retina
    • posterior ciliary artery
      • supplies the outer retina (photoreceptors)
104
Q

What muscles control the eyelid?

A
  • orbicularis oculi
    • depresses the upper lid (eyelid closes)
    • innervated by CNVII
  • levator palpebrae superiorsis
    • elevates upper lid (eyelid opens)
    • innervated by CNIII

Danielle's MD1 (6 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions