Name three neuromodulators
Dopamine, adrenaline and serotonin
What happens during local anaesthetics?
Sodium channels are blocked in that area
Where is the motor cortex?
In the pre-central gyrus in the frontal lobe
Where is the sensory cortex?
In the post-central gyrus in the parietal lobe
Where does the spinal cord terminate?
What are the two types of fast twitch muscle fibres?
2A glycotic (anaerobic) and oxidative (aerobic) and 2B glycotic (anaerobic)
What are the three bones of the ear?
Malleus, incus and stapes
What nerve innervates the tensor tympani?
The Vii nerve
Are most of the hair cells in the cochlear afferent or efferent?
95% are of the outer hairs are afferent and the inner hairs are efferent
What is the function of the round window in the cochlea?
It releases fluid and pressure
Calcium moving into what side of the cochlea hairs causes depolarisation?
Moving towards the tectoral side
What cranial nerves are parasympathetic?
What areas of the CNS do parasympathetic nerves come from?
They are some cranial nerve and sacrum nerves
What is the sympathetic neurotransmitter?
What is the parasympathetic neurotransmitter?
Do somatic nerves have ganglia?
No, because they do not synapse after the CNS
What is the somatic neurotransmitter?
Are somatic neurones myelinated?
What type of muscle do autonomic neurones go to?
Are autonomic neurones myelinated?
Pre-ganglion yes but post-ganglion no
What are the autonomic neurotransmitters?
ACh and adrenaline
What do alpha 1&2 receptors do?
What are three fast neurotransmitters?
ACh, Glutamate, and GABA
What are the branches of the trigeminal nerve?
1. Ophthalmic nerve 2. Maxillary nerve 3. Mandibular nerve
What is a nerve impulse?
The signal used by neurones to transmit information between different spatial locations
What are dystrophies?
They are genetically determined, destructive and mainly progressive disorders of muscle
What does the media of the eye contain?
The vitreous, hyaluronic acid (GAG)
What makes up the parasympathetic component of the autonomic nervous system?
The cranial and sacral outflow
What makes up the sympathetic components of the autonomic nervous system
The sympathetic chain (T1-L2) and the adrenal gland
What is axonal transmission?
Transmission of information from location A to location B
What is synaptic transmission?
Integration / processing of information
Can a neurone use more than one neurotransmitter?
Where is ACh used?
At neuromuscular junctions, in the brain and in the spinal cord
Where is noradrenaline?
It the heart and the central nervous system
Where is dopamine used?
In the basal ganglia
Where is serotonin used?
In the brain
Is GABA excitatory or inhibitory?
It is the main inhibitory transmitter
What does the dorsal stream from the primary visual cortex detect?
The distance and where the object is
What does the ventral pathway from the primary visual cortex detect?
What the object is
What does the medial rectus do?
Adducts the eye
What does the lateral rectus do?
It abducts the eye
What does the superior rectus do?
It elevates, intorts and adducts the eye
What does the inferior rectus do?
It depresses, extorts and adducts the eye
What does the superior oblique do?
It intorts, depresses and abducts the eye
What does the inferior oblique do?
It extorts, elevates and abducts the eye
What does vestibular eye movement do?
It holds images of the seen world steady on the retina during brief head rotations or translations
What does visual fixation do?
It holds the image of a stationary r object on the fovea by minimising ocular drifts
What does optokinetic eye movement do?
It holds the images of the seen world steady on the retina during sustain d head rotation
What does smooth pursuit eye movement do?
It holds the image of a small moving target on the fovea. It holds the image of a small near target on the retina during linear self-motion
What do nystagmus quick phases do?
Reset the eyes during prolonged rotation and direct gaze towards the oncoming visual scene
What do saccades do?
Bring images of objects of interest into the fovea
What does vergence eye movement do?
It moves the eyes in opposite directions so that images of a single object are placed or held simultaneously on the fovea of each eye
What is the function of the basal ganglia in the sensorimotor system?
The basal ganglia determines what to do and the cerebellum determines how to do it
What is a motor neuron pool?
A collection of motor neurone innervating a single skeletal muscle. They are organised somatotropically
What is the pneumonic for the motor or sensory function of the cranial nerves?
Some say money matters but my brother says big breasts matter most
What are the parasympathetic cranial nerves?
3, 7, 9, 10
What does the olfactory nerve do?
It senses smells
Where does the olfactory nerve start?
The cribiform plate
Where does the olfactory nerve project to?
The entorhinal cortex in the anteriomedial part of the temporal lobe.
How does the olfactory nerve work?
Air gets sucked in and hits the hair fibres on the olfactory to synapse with second generation neurones that send impulses to the brain
How do the hypothalamus and the olfactory nerve work together?
The hypothalamus remembers the emotions that come with the smell from the olfactory nerve
What is CN 1 ?
The olfactory nerve
What is CN 2?
The optic nerve
What does the optic nerve detect?
What nerves control eye movement?
What does CN 6 do?
Abducts the eye
What muscle does CN 4 innervate ?
The superior oblique muscle of the eye
What muscle does CN 6 innervate?
The lateral rectus muscle
What is CN 3?
The oculomotor nerve
What is CN 4?
The trochlear nerve
What is CN 6?
The abducens nerve
What muscles does CN 3 innervate?
The superior rectus, the medial rectus, the inferior rectus and the inferior oblique muscles. Also the locator and pupillary constrictors
What is the path of the oculomotor nerve?
It originates from the midbrain, near the posterior cerebral arteries, through the cavernous sinus, through the superior orbital fissure and it branches.
What is the path of the trochlear nerve?
It originates in the midbrain, decusses centrally, exits dorsally near the posterior cerebral arteries, through the cavernous sinus and through the superior orbital fissure
What is the path of the abducens nerve?
It originates in the pons, along the petrous temporal bone, through the cavernous sinus and through the superior orbital fissure
What is CN 5?
The trigeminal nerve
What does the trigeminal nerve do?
It gets sensation from the face and mouth and control the muscles of mastication
What happens in Meckel's cave?
The trigeminal afferents meet
What muscles does the mandible division of the trigeminal innervate?
The temporalis, the masseter and pterygoids
What is CN 7?
The facial nerve
What does the facial nerve do?
Somatic motor innervation of the muscles of facial expression. Visceral motor innervation of the lacrimal gland, submandibular and sublingual salivary glands. It senses the taste buds of the anterior two thirds of the tongue
What are the five branches of the facial nerve?
The temporal, zygomatic, buccal, mandibular and cervical
What is the nucleus of the somatic motor component of the facial nerve?
The facial motor nucleus. It acts on the muscles of facial expression.
What is the nucleus of the visceral motor component of the facial nerve?
The superior salivatory nucleus. It goes to the pterygopalatine (lacrimal glands) and submandibular ganglia (submandibular and sublingual salivary glands) and stimulates secretion
What is the nucleus of the special sense (taste) component of the facial nerve?
The solitary tracts which goes to the geniculate ganglia, which detect taste from the taste buds
What do the corticobulbar fibres innervate?
The contralateral side of the lower face. The bilateral side of the upper face.
What is CN 8?
The vestibocochlear nerve
What does the vestibulocochlear nerve do?
It conducts auditory and vestibular-related impulses from the organ of Corti, the semicircular canals, the utricle and the saccule
Where does the vestibulocochlear nerve originate?
In the pons, it goes through the internal acoustic meatus to get to the vestibular ganglia and the spiral ganglion in the cochlea
What does the vestibular branch of CN 8 do?
It goes to the vestibular ganglia, which receives fibres from the semicircular canals, the utricle and the saccule. It can accelerate the position of these things
What does the cochlea branch of CN 8 do?
It goes to the cochlear ganglia, which receives input from the organ of Corti about hearing
What is CN 9 ?
The glossopharyngeal nerve
What is the path of the glossopharyngeal nerve?
It emerges from the lateral sulcus of the medulla and exits the skull via the jugular foremen, accompanied by the vagus and accessory nerves
Where are the presumptive neural crest cells?
They run dorsolaterally along the neural groove
What do the neural crest cells form?
The sensory ganglia of the spinal cord; schwann cells; adrenal medulla and the meninges and the dermis
What is the function of CSF?
At what point do eyes form in an embryo?
When does CNS myelination take place in an embryo?
How much does the speed of impulse increase between a neonate and a two year old?
The speed of impulse depends on myelination. At neonate it is 20-25m/s and at two years it is 40-60m/s and as far as I am aware it doesn't get any quicker
What is a lemnisci?
A narrow strip of fibres
What is the difference between a funiculi or a fasiculi?
A funiculi is a 'rope' or 'cord' of fibres. A fasiculi is a 'bundle' of fibres
What is a capsule?
A sheet of white matter fibres bordering a nucleus of grey matter
What is a cortex?
A laminated grey matter on the outside of the brain
What is a nucleus?
A nucleus is a collections of nerve cell bodies within the CNS
What is a ganglia?
A collection of nerve cell bodies outside the CNS or inside the CNS that have a capsule (basal ganglia)
What does the frontal lobe do?
It controls voluntary movement on the opposite side of the body. The frontal love dominant hemisphere controls speech and writing. It controls intellectual functioning, thought processing, reasoning and memory
What is the basal ganglia made up of?
The caudate nucleus, the putamen and the globus pallidus
What does the basal ganglia control?
Motor control, cognition and non-motor behaviour
What separates the cerebellum and the brainstem?
The 4th ventricle, the cerebellum forms part of its roof
What are transverse folia?
The folds of cerebellum
What is the function of the cerebellum?
It is involved in the coordination of voluntay motor movement, balance and equilibrium and muscle tone (posture)
What makes up the tegmentum of the midbrain?
It is the ventral (front) part. It consists of the red nucleus, reticular formation and the substantia nigra
What makes up the tectum of the midbrain?
It is the dorsal side (back) made of the inferior and superior colliculi
What is the function of the hippocampus?
It is critical for episodic, short term and spatial memory. It is essential for constructin mental images
What is anterograde tracing?
It traces from the neuronal cell bodies to the axon terminals
What is retrograde tracing?
It traces from the axon terminals to the neuronal cells bodies. It can be double labelled, which detects two separate branches going to the same cell body
What are bidirectional tracers and what is wrong with them?
They can be anterograde or retrograde so it can move down both branches of the neurone but not the neurone cell body
What are class A experiments?
Some behavioural, physiological or pharmagological variable is manipulated and the consequent effects on brain structure/activity are determined
What does an EEG measure?
It is an indication of regoinal brain activity
What is a class B experiment?
Some brain aspect of brain structure or activity is manipulated and the consequent effects on behaviour/physiology/endocrinology is determined
How can the brain be manipulated in a class B experiment?
Suppression of neural activity (mechanical, electrolytic, chemospecific). Activation of neural activity (electrical stimulation and ECT)
What do excitatory neurotransmitters do?
They depolarise the cell membrane, which icnreases the probability of an action potential being elicited, causing an excitatory post-synaptic potential (EPSP)
What do inhibitory neurotransmitters do?
They hyperpolarise the cell membrane, which decreases the probability of an action potential bein elicited, causing an inhibitory post-synaptic potential (IPSP)
What is a neurone?
It is a highly specific interconnection that collect information, process it and provide memory capacity, they also generate signals to produce a response
What is a neurotransmitter?
It a molecule that interacts with receptors to cause a change a cell cell function
Name an excitatory neurotransmitter
Name an inhibitory neurotransmitter
What are neuroglia?
Supporting cells that have a protective role and provide structural and functional roles
What are astrocytes?
They are multipolar cells that help control the neuronal environment, influencing local neurotransmitter and electrolyte concentrations. They regulate the blood-brain barrier by foot processes close to the capillaries
What do radial glia do?
They are crucial in guiding developing neurons
What do oligodendrocytes do?
They are most numerous cell in the CNS, they produce myelin sheath that insulate CNS axons. They are in both grey and white matter
What cells provide a barrier between the CSF and the brain?
What cells are the resident macrophages of the CNS
Microglia. They are in the meninges, brain parenchyma and vasculature. They contribute to CNS homeostasis
What does the innervation pathway of the skeletal muscle consist of?
The anterior horn cells, the corticospinal tract, the basal ganglia, the cerebellar systems and the primary motor cortex
What type of innervation do myofibrils have?
They have both afferent and efferent innervation. The afferent innervation is from the muscle spindles and from the golgi tendon organs
Why are skeletal muscle fibers not fixed when histologically tested?
They are frozen so when you warm them up the enzymes still work and are easily detectable
What is the sclera of the eye?
The sclera is a tough outer collagen layer that protects the eye. The extraocular muscles attach to the sclera
What is the function of the cornea?
It transmits light and refracts it. It has 2/3rds of the focusing power of the eye. It must be transparent and it has a smooth spherical surface.
What is the function of cornea endothelium?
It is the innermost layer of the cornea. It keeps the corneal clarity by pumping water out of it
Why must the cornea remain dehydrated?
Because the water molecules alter the regular spacing between collagen fibres, causing opacity. It is never regenerated.
What is the limus?
Where the cornea joins the white of the eye
What is the epithelium of the cornea?
It is the outer layer of the eye, it has many layers that are constantly regenerated by limbal stem cells
Where is the iris and what does it consist of?
It directly overlies the lens. It consists of the pupil, the coloured part of the eye, both the sphincter and the radial muscles
How is the sphincter muscle of the eye innervated and what does it do?
It is parasympathetically innervated. It is circumferenital in the pupil margin and causes the pupil to constrict
How is the dilator pupillae muscle innervated, where is it and what does it do?
It is sympathetically innervated. It is radial and in the outer iris. It causes the pupil to dilate
What and where is the choroid?
It is a thin, vascular structure between the retina and the sclera.
What is the function of the choroid?
It is the vascular supply of the outer retina. It absorbs stray photons, acts as a heat sink and provides nutrients to the outer retina.
What is the ciliary body?
It is a circumferential structure surrounding the lens. It has glandular epithelium that produces aqueous humour and has smooth muscle that controls the alteration of lens convexivity to focus on things in the distance
What it the function of aqeuous humour and how is it secreted?
It is secreted from the glandular epithelium via active secretion and ultrafiltration that is similar to plasma. It provides nutrients to the cornea and the lens, maintains the balance between production and drainage and then drains via the trabecular network.
What is the path of the aqeuous humour?
It circulates from the posterior to the anterior chamber through the pupil
What is the lens of the eye?
It is a flexible, crystal-like biconcave disc. The lens fibres are progressively ladi down over life, so it thickens with age. It has 1/3rd of the focus power of the eye, making distances to near.
What holds the lens in place?
What is the virteous?
A thick, gel-like substance that fills the posterior chamber. It is 99% water and hyaluronic acid. It is 80% of the volume of the globe and it degrades with age
What is the retina?
It is the film of the eye, the site where light energy is converted to electrical impulses for the brain. It lines the innermost surface of the eye and contains photoreceptors
What are the ten layers of the retina?
The retinal pigment epithelium; photoreceptors; the external limiting membrane; the outer nuclear layer; the outer plexiform; the inner nuclear layer and inner plexiform; the ganglion cell layer; the optic fibre layer and the internal limiting membrane
Where do the four recti extraocular muscles arise from?
The annulus of zinn at the apex of the eye
What is the function of the eyelid?
It glides over the front surface of the eye to protect it and distribute tears
What is the anterior lamella?
It is the front of the top eyelid. It is made of skin and muscle (the orbicularis ocularis)
What is the posterior lamella?
It is the back of the top eyelid. It is made of the tarsal plate (rigid), it contains glands and is made from the conjunctiva
What is the conjuntiva?
A clear covering over the sclera. There are several regions: the tarsal plate, the fornix, bulbar. It contains goblet cells and lymphatics that acts as an immunse response
Where is the tarsal plate?
It is on the back of the eyelid and is tightly adherent.
Where is the fornix of the conjunctiva?
It is a recess behind the lens that contains lots of glands
Where is the bulbar of the conjunctiva?
It is over the globe of the eye, it is loosely adherent and allows th eye to move freely.
What are the three layers of tears?
An anterior lipid layer; a middle aqueous layer and a posterior mucous layer
What are the functions of tears?
They are protective, antibacterial, provide nutrition to the cornea and provide a smooth surface to the eye
What is the blood supply of the inner retina?
It is supplied by the central retinal artery. This branches into the superior and inferior, temporal and nasal branch retinal arteries. The retinal capillaries have tight junctions and form the blood retinal barrier.
What does the blood supply of the retina drain into?
The opthalmic veins and then the cavernous sinus
What is the blood supply of the external retina?
It is supplied by the posterior ciliary arteries, which become the choroidal arteries, which become the chorocapillaries, which are leaky vessles.
What is the lymphatic system of the eye?
There are no lymphatics in the eye itself. The lower and medial central lid drain into the submandibular lymph node. There is also a pre-auricular lymph node
What are the cochlear nuclei?
The anterior ventral, posterior ventral and dorsal. The regoins each have a tonotopic map
What is the calyx of Held?
A fast synapse between the anterior ventral cochlear nuclei and the medial superior olive
What does the superior olive do concerning the ear?
It is the site of sound localisation.
What does the medial superior olive detect?
It performs low frequency analysis and recognises interaural time differences. It receives faithful inputs from the calyx of Held on both sides
What does the lateral superior olive detect?
It performs high frequency analysis and detects interaural intensity differences
What does the inferior colliculus do?
It is the site of convergence of projections with complex frequency responses. It is responsible for attention reflexes, the startle response and learned reflexes. It creates the tonotopic map
Where does the input to the inferior colliculus come from?
The monoaural input is from the dorsal cochlear nuclei and the biaural is from the superior olive
What is the nucleus, target muscle and function of the somatic motor function of the glossopharyngeal nerve?
The nucleus ambiguus send impulses to the stylopharyngeus to elevate the pharynx
What is the nucleus, ganglia, target and function of the visceral motor component of the glossopharyngeal nerve?
The inferiory salivatory nucleus sends impulses via the OTIC (not optic) ganglion to the parotid gland and activates secretion
What is the nucleus, ganglia, target muscle and function of the somatic sensory component of the glossopharyngeal nerve?
The spinal trigeminal tract sends impulses via the superior glossopharyngeal ganglion to the skin of the external ear and starts somatic sensation
What is the nucleus, ganglia, target muscle and function of the visceral sensory component of the glossopharyngeal nerve?
The solitary tract sends impulses via the inferior glossopharyngeal to the posterior thirs of the tongue, the pharynx and the eustachian tube to detect touch pain and temperature
What is the ganglia, target muscle and function of the special sensory component of the glossopharyngeal nerve?
The ganglia is the inferior glossopharyngeal and it sends impulses to the taste buds in the posterior third of the tongue to detect taste
What is CN 10?
The vagus nerve
What is the path of the vagus nerve?
The vagus nerve emerges from the medulla to exit the skull through the jugular foramen, accompanied by the glossopharyngeal nerves
What is the nucleus, target muscle and fuction of the somatic motor component of the vagus nerve?
The nucleus ambiguus sends impulses to the muscles of the pharyn and larynx to control swallowing and speech
What is the nucleus, ganglia, target muscle and function of the visceral motor component of the vagus nerve?
The dorsal motor nucleus sends impulses via various ganglia to the viscera of the thoracic and abdominal cavities, which has an autonomic effect on visceral organs
What is the nucleus, ganglia, target muscle and function of the somatic sensory component of the vagus nerve?
The spinal trigeminal tract sends impulses via the superior ganglion to the external ear to control somatic sensation
What is the ganglia, target muscle and function of the visceral sensory component of the vagus nerve?
The inferior ganglion sends impulses to the pharynx and larynx, the aortic arch and body, and the thoracic and abdominal viscera to detect visceral sensation
What is the nucleus, target muscle and function of the special sensory component of the vagus nerve?
The solitary tract sends impulses to the posterior pharynx to detect taste
What does the recurrent laryngeal branch off and what does it supply?
The recurrent laryngeal is a branch of the vagus nerve and it supplies all the intrinsic muscls of the larynx except the cricothyroid muscle, compression or damage causes hoarseness secondary to paralysis of the vocal cords
What is CN 11?
The accessory nerve
What does the accessory nerve supply?
The sternocleidomastoid and trapezius muscles
Where are the cell bodies of the accessory nerve?
The cell bodies are in the ventral horn of the upper five segments of the spinal cords. The fibres go up throught the foramen magnum and become the acessory nerve when they join the trigeminal nucleus.
How does the accessory nerve exit the skull?
Through the jugular foramen
What is cranial nerve 12?
The hypoglossal nerve
What does the hypoglossal nerve supply?
The intrinsic and extrinsic muscles of the tongue
Where are the cell bodies of the hypoglossal nerve?
The are located in the hypoglossal nucleus, which lies between the dorsal motor nucleus of the vagus and the midline of the medulla. It exits the skull through the hypoglossal canal
What is the function of the glossopharyngeal nerve?
Tongue movements of speech, food manipulation and swallowing
What is the defintion of pain?
An unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage.
What are some key features of pain?
Always subjective; A sensation; Always unpleasant; An emotional experience; A psychological state
What is acute pain?
Short term pain of less than 12 weeks duration
What is chronic pain?
Continuous long term pain of more than 12 weeks duration or pain that persists after the time that healing would have been thought to have occurred after trauma or surgery
What are the two types of chronic pain?
Cancer chronic pain and non-cancer chronic pain
What is nociceptive pain?
Pain that arises from actual or threatened damage to non-neural tissue and is due to the activation of nociceptors.
What is neuropathic pain?
Pain arising as a direct consequence of a lesion or disease of the somato-sensory system
What are nociceptors?
Nociceptors are sensory neurons that are found in any area of the body that can sense pain either externally or internally
Where are nociceptor cell bodies?
Either in the dorsal root ganglion (body) or the trigeminal ganglion (face / head / neck)
What type of neurons are in the dorsal ganglion?
Pseudo-unipolar first order neurones
What does the spinothalmic tract convey?
Sensory pathway that carries pain, temperature and crude touch information from the body
What is the path of second order neurones in the spinothalamic tract?
Originate in the spinal cord; Axons decussate at a few levels above the site of entry then form the anterolateral tract then terminate in the thalamus (ventral posterior lateral nucleus)
What do the sections of the anterolateral tract convey?
The anterolateral tract is the spinothlamic tract above it's dessucation. The lateral side conveys pain and temperature. The anterior side conveys crude touch.
What is the trigeminothalamic tract?
Sensory pathway that carries pain, temperature and crude touch information from the face / head / neck
What is the path of the first order neurones of the trigeminothalamic tract?
Central projections enter the pons; descend to the medulla forming the spinal trigeminal tract; synapse in the spinal trigeminal complex
What is the path of the second order neurones in the trigeminothalamic tract?
Originate in the spinal trigeminal complex; Terminate in the thalamus (ventral posterior medial nucleus)
What cranial nerves make up the trigeminothalamic tract?
It receives contributions from the trigeminal, facial, vagus and glossopharyngeal nerves.
What is the function of the insular cortex?
Plays a role in perception, motor control, self awareness and interpersonal experience; may also play a part in addiction; This is where the degree of pain (experienced or imagined) is judged; Contributes to the subjective aspect of pain perception
What is the function of the cingulate gyrus?
Intricately linked with the limbic system which is associated with emotion formation and processing, learning and memory; maintains reciprocal connections with other pain processing areas
What is periaqueductal grey?
Gray matter located around the cerebral aqueduct; Receives input from cortical and sub-cortical areas; Projects onto neurons in the dorsal horn so it can modulate afferent noxious transmission
What are the components of the limbic system?
The hippocampus, amygdala, mamillary body and hypothalamus, fornix and cingulate gyrus
What is the papez circuit?
It is another name for the limbic system
Where is short term memory remembered?
In the prefrontal cortex
What are the two types of long-term memory?
Implicit and Explicit
What are the two types of explicit long term memory?
Episodic (day to day events in the hippocampus) and semantic (things you have learnt)
What are the three types of implicit long-term memory?
Skills and habits like riding a bike (cerebellum and basal ganglia); conditioned reflexes (cerebellum); emotional (amygdala)
What hormones does the posterior pituitary gland create?
it synthesises oxytocin and ADH fro the neuroendocrine system
What hormones does the anterior pituitary gland create?
It secretes prolactin, FSH/LH, and TSH for the portal vein system
What is the amygdala?
A grey matter structure above and in front of the hippocampus
What is the function of the amygdala?
Receives highly processed information; Produces instinctive emotional output; Responsible for emotional memory
What is dualism?
The brain and the body are two separate entities, the brain cannot exist outside of the body and the body cannot think
What is neuropsychiatry
Neuropsychiatry is the branch of medicine dealing with mental disorders attributable to diseases of the nervous system (brain).
What is perception?
The organization, identification, and interpretation of sensory information in order to represent and understand the environment
What are the three cerebellar nuclei?
The dentate nucleus, the emboliform nucleus, the globose nucleus and the fastigial nucleus
What is the function of the tensor tympani?
It attaches to the malleus and contraction of the muscle dampens the bones movement to protect the receptor apparatus in the internal ear during continuous loud noises
What is mental health?
Mental health is a state of well-being in which the individual realises his or her own abilities, can cope with the normal stresses of life, can work productively and fruitfully and is able to make a contribution to his or her community
What is the function of the stapedius muscle?
It connects to the stapes and when it contracts it dampens the movement of the muscle to protect the receptor apparatus during continuous loud sounds
What function does the cortex have on the auditory pathway?
It retains the tonotopic map
What are the bones in the middle ear?
Malleus, incus and stapes
What is the function of the bones in the middle ear?
To push sound into the oval window of the cochlea
Where is the organ of Corti?
On the basilar membrane in the cochlea
Do you need energy to get the cochlear hair cells to detect sound?
What are the three chambers of the cochlea?
The scala tympani, cochlea duct (scala media)and the scala vestibuli
What fluid is in the scala media?
What fluid is in the scala tympani and the scala vestibuli?
Where is the stria vascularis and what is it's function?
It is in the scala media. It is striated and vascular. It pumps K+ ions into the scala media.
How many outer and inner hair cells do we have?
About 12,000 outer hair cells and 3,000 inner hair cells
What shape and how many outer hair cells do we have?
They are tubular and we have 12,000, compared to 3,000 inner hair cells
Do inner hair cells or outer hair cells do most of the transduction?
Inner hair cells do 95% of the transduction
What is the tectorial membrane made of?
It is a collagenous membrane
What happens when the basliar membrane moves?
The outer hair cells move and the inner hair cells are covered by a fluid motion.
Do the hair cells in the cochlea affect amplification?
Yes, a little bit. When the active movemnts of the outer hair cells are in phase with the basilar membrane movement the sound if amplified.
What are the shapes of the outer hair cell and inner hair cell bundles?
Outer hair cells have a V-shaped bundle and inner hair cells have a straight bundle
How does the volume of the sound affect the resolution?
As the noise level increases, the resolution of the music goes down.
How is intensity (loudness) of sounds measured?
It is the number of hairs responding and the firing rate of the cells
Which hair cells perform sound transduction?
Inner hair cells
Which hair cells produce amplification?
Outer hair cells
What is the difference between the function of the autonomic and somatic nervous system?
The autonomic functions without consciousness (involuntary). The somatic has conscious, voluntary regulation
Do somatic fibres synapse after leaving the CNS?
No, it is a single neurone from the CNS to the effector organ
Do autonomic fibres synapse after they leave the CNS?
Yes, they synapse at a ganglion after they leave the CNS in a two-neuron chain.
What does the autonomic nervous system innervate?
Smooth muscle, cardiac muscle and glands
What does the somatic nervous system innervate?
Are somatic fibres myelinated?
Are autonomic fibres myelinated?
Preganglion - yes
Postganglion - no
What is the neurotransmitter of the somatic nervous system?
What is the neurotransmitter of the autonomic nervous system?
At the ganglion - ACh
To the target - ACh or NAd
What does the autonomic system do that you can't see?
Releases adrenaline; increases BP; the liver releases glucose as energy for muscles; digestion slows down or stops; the sphincters close; corticol is released; they heart pumps faster
What does the autonomic system do that you can see?
The pupils dilate; the mouth goes dry; the neck and shoulder muscles tense; there is sweating; muscles tense for action; there is fast breathing
What is the results of transmitter-gated ion channels on the post-synaptic membrane that are sensitive to specific neurotransmitter substances?
Either depolarisation of hyperpolarisation depending on the channel type (excitatory or inhibitory)
Are individual retinal ganglion cells ever electrically silent?
What inhibits adjacent areas of retinal ganglion cells?
The action of the horixontal and amacrine cells.
Where do inputs to retinal gnaglion cells originate from?
Photoreceptors in circumscribed areas of the retina. The receptive field varies in size across the retina
What do parvocellular retinal ganglion cells detect?
Low contrast. They have high linear spatial resolution
What do koniocellular retinal ganglion cells do?
The detect blue and yellow colours
What do magnocellular retinal ganglion cells do?
They have high contrast but low resolution. They detect motion but are colour blind
What is the visual pathway?
Photoreceptors -> retinal ganglion cells -> optic nerve head -> optic nerve -> optic chiasm -> optic tract -> lateral geniculate nucleus -> optic radiation -> primary visual cortex
What is the purpose of the optic chiasm?
Fusion of the two eyes and preventing double vision
What is a spontaneous seccade?
It is a visual search of the environment. We have 20/minutes
What is a reflexive saccade?
The occur due to visual or auditory cues/ They have short reaction times
What are voluntary saccades?
They carry the eyes to a predetermined location corresponding to the position of a visual target or sounds
Can saccades be voluntarily suppressed?
Yes, to maintain a steady foveal function
What does the frontal eye field do?
Generate voluntary saccades; suppress saccades; vergence and smooth pursuit; memorgy-guided saccades.
What do the supplementary eye fields do?
They guide saccades during comple tasks; contribute to predictive smooth pursuit; shifts from an autonomic to voluntary behaviour
How does the parietal cortex innervate the pursuit system?
It enhances attention of the moving target
What are unipolar sensory neurones?
They are afferent neurons bringing sensory information via the dorsal roots to the CNS.
Where are unipolar sensory neurones cell bodies?
In the dorsal root ganglion
What and where are the processes of a unipolar sensory neurone?
The peripheral process ends in the skin, a muscle or a joint. The central process ends in the dorsal horn of the spinal cord.
What are multipolar neurones?
They are efferent neurons sending motor impulses and information via the ventral roots to the muscles
Where are multipolar neurone cell bodies?
In the ventral horn of the spinal cord
Where are alpha motor neurones?
In the ventral horn of the grey matter
Where do alpha motor neurones project to?
From the ventral horn via a ventral into the spinal tract.
How are alpha motor neurones organised in the ventral horn?
Neurones that control proximal muscles are located medially, the distal msucles are located laterally
What is a motor unit?
A single alpha motor neurone and all the muscle fibres it innervates
How does the number of muscle fibres in a motor unit affect the movement resolution?
The fewer fibres there are, the higher the movement resolution
How does the number of motor neurones innervated affect the muscle?
The more motor neurones that are activated the more muscle fibres contract and the more power you get from the muscle
What is the function of the muscle spindles?
They detect stretch of the muscle regardless of the current muscle length
What are muscle spindles made of?
Intrafusal fibres with sensory fibres coiled around them.
What innervates intrafusal muscle fibres?
Gamma motor neurons
What are the nerve roots in the cervical enlargement of the spinal cord?
What are the nerve roots in the lumbar enlargement of the spinal cord?
How much higher are the cervical nerve segements than their corresponding vertebrae?
1 spine higher
How much higher are the thoracic nerve segments than their corresponding vertebrae?
2 spines higher
How much higher are the lumbar nerve segments than their corresponding vertebrae?
3-4 spines higher
What does the white matter of the spinal cord contain?
Ascending and descending fibres
What does the grey matter of the spinal cord contain?
Nerve cell bodies, dendrites and synapses
Where in the spinal cord has the most white matter?
The higher up regions
What is the shape of the grey matter in the spinal cord?
It is an 'H' shape with 2 ventral horns and 2 dorsal horns.
Where are the lateral horns and what do they contain?
In the thoracic and upper lumbar sections of the spinal cord. They contain pre-ganglionic sympathetic neurones.
What do the dorsal columns detect?
Proprioception, vibration and fine touch.
Where does the dorsal column send information to?
The fasciculus gracilis from the lower body and the cuneatus from the upper body.
Where do the dorsal column fibres decussate?
In the medulla, where they become the medial lemniscus. These ascend to the thalamus then the cortex.
What does the spinothalamic tract detect?
Pain, temperature (lateral), crude touch (medial)
Where do the fibres of the spinothalamic tract decussate?
The fibres ascend on the same side for 1 or 2 segments then cross before ascending to the thalamus
What does the spinocerebellar tract do?
What are the ascending tracts?
The dorsal column; the spinothalamic tract; the spinocerebellar tract and the spinoreticular tract.
What does the spinoreticular tract detect?
What are the descending tracts?
The corticospinal tract; the tectospinal tract; the rubrospinal tract; the vestibulospinal tract; the reticulospinal tract
What does the corticospinal tract do?
It has control of voluntary muscles
What does the tectospinal tract do?
Controls head-turning in response to visual stimuli
What does the rubrospinal tract do?
It assists in motor function
What does the vestibulospinal tract do?
It controls muscle tone and posture
What does the reticulospinal tract do?
It controls the spinal reflexes
What cells does motor command originate from?
Pyramidal cells in the motor cortex.
Where are the cell bodies of the motor command neurones?
In the grey matter of the cortex
How do the pyramidal cells project motor commands?
Either directly to the lower motor neurones via the pyramidal tract or indirectly through the spinal cord via the extra-pyramidal tract.
Do most cortical projections innervate contralateral or ipsilateral motor units?
Where does the cerebellum receive input from?
The cerebral cortex, the brain stem nuclei and the sonsory receptors.
What does the cerebellum control?
Voluntary motor movement, balance and equilibrium, and muscle tone
How many lobes does the cerebellum have?
What separates the cerebellar lobes?
The falx cerebelli.
What separates the cerebellum from the occipital lobe?
The transverse fissure and the tentorium cerebelli.
What separates the cerebellum from the pons and the medulla?
The 4th ventricle. The cerebellum makes up the floor of it.
What is the medullary velum?
It is non-nervous tissue that lines the 4th ventricle above and below.
How does the 4th ventricle communicate with the subarachnoid space?
Through the median aperture and the two lateral apertures.
What does the cerebral aqueduct connect?
The third and fourth ventricles
What are the three layers of the cerebellum?
Purkinje (monolayer of large cells)
Granular (lots of small cells)
What are the inputs of the cerebellum and through what?
Mossy fibres (middle peduncle)
Climbing fibres (inferior peduncle)
What is the output of the cerebellum?
Through the Purkinje cell axons, mostly to the dentate nucleus
What does the superior peduncle link to the cerebellum?
The nuclei in the midbrain, the diencephalon, the cerebrum. It is mainly efferent fibres
What does the middle peduncle link to the cerebellum?
The pons and the midbrain
What does the inferior peduncle link to the cerebellum?
Nuclei in the medulla and the ascending and descending tracts.
Where do the climbing fibres come from?
The olivocerebellar nuclei via the inferior peduncle
What do the medulla and cerebellum convey information about?
Proprioception and vestibular inputs, via the inferior peduncle
What do the pons and cerebellum convey information about?
Voluntary motor output, it is via the middle peduncle
Where do the purkinje cell axons go once they reach the dentate nucleus?
Dentate nucleus -> superior cerebellar peduncle (where they decussate) -> thalamus -> red nucleus
What is the largest commisural bundle in the body?
The corpus callosum
What does the corpus callosum do?
Unites the fibres of similar areas between the two hemispheres
What makes up the striatum of the basal ganglia?
The caudate and putamen nucleus
What is the direction of CSF flow through the ventricles?
Lateral ventricles -> interventricular foramen -> third ventricle -> cerebral aqueduct -> fourth ventricle -> lateral and medial apertures -> subarachnoid space -> arachnoid villi
What makes up the limbic system?
Hippocampus, diencephalon, amygdala, fornix, cingulate gyrus
What does the amygdala do?
Stores memories associated with emotional events. Reward and fear
What does the basal ganglia do?
Volutary movement, it uses dopamine
What is substance P and what does it do?
It is a neuropeptide. It is in the spinal cord and the brain. It binds neurokinin-1 receptors. Transmits pain to the CNS.
What do opioids do?
Activate opioid receptions. Close voltage gated calcium channels. Stimulates potassium efflux
Where are tendon golgi and what do they do?
Junction between tendon and muscle. They monitor tension. They are afferent nerve endings surrouding collagen bundles in tendons.
What separates the striatum?
It is divided by the internal capsule into the caudate nucleus and the putamen.