Intro to Nervous System

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Questions and Answers

What are the functions of nerves?

It allows us to sense our environment- both internal and external to the body.

  1. It has sensory functions through sight, smell, taste, touch, hearing, balance etc.
  2. It allows us to respond to the environment through the motor functions. (a) Voluntary- locomotion through skeletal muscle movement. (b) Involuntary- smooth muscle, glands and cardiac muscle.
  3. Reflex functions- automatic, protective response

What are the anatomical subdivisions of the nervous system?

  1. Central nervous system- consisting of the brain and the spinal cord
  2. Peripheral nervous system- consisting of all nerve tissue other than the CNS, including the spinal nerves, cranial nerves and the autonomic nerves.

What are the parts of the peripheral nervous system?

The peripheral nervous system includes:-

  1. Spinal nerves- connects with spinal cord
  2. Cranial nerves- connect with brain
  3. Autonomic nerves- (a) supplying organs, smooth muscle, glands (b) visceral afferents (c) sympathetic nerves (d) parasympathetic nerves

What is a ganglion?

<p>Collection of nerve cell bodies (in the PNS)</p> Signup and view all the answers

What is a tract?

<p>Bundle of axons in the CNS</p> Signup and view all the answers

What is a nerve?

<p>Bundle of axons in the PNS</p> Signup and view all the answers

What is the role of the cell body of the neuron?

<p>It sends and receives electric impulses. The cell body is also responsible for protein synthesis and provides metabolic support for the neuron.</p> Signup and view all the answers

What is the myelin sheath? What is its role?

<p>Myelin is an insulating layer, or sheath that forms around nerves, including those in the brain and spinal cord. It is made up of protein and fatty substances. This myelin sheath allows electrical impulses to transmit quickly and efficiently along the nerve cells.</p> Signup and view all the answers

What is the role of the axon?

<p>The function of axons is to carry electrical impulses that are the means of communication within the brain, and between the brain and the rest of the body.</p> Signup and view all the answers

What is the role of dendrites?

<ol> <li>The functions of dendrites are to transfer the received information to the soma of the neuron.</li> <li>It receives the data or signals from another neuron and collects and stores all incoming information from axon terminals.</li> </ol> Signup and view all the answers

What are the different modalities of nerve fibres?

<ol> <li>Somatic sensory function- somatic relates to the body wall, skeletal muscle, internal walls.</li> <li>Somatic motor function</li> <li>Special sensory function- sight, hearing, balance</li> <li>Visceral afferent function- visceral meaning the internal organs like the heart.</li> <li>Sympathetic function</li> <li>Parasympathetic function</li> </ol> Signup and view all the answers

What is the ability of a nerve carrying different fibres of different modalities?

<p>A single nerve fibre can only conduct action potentials in relation to one of the modalities. However, a nerve carries mixed bundles of nerve fibres.</p> Signup and view all the answers

What is a motor function in a nerve?

<p>Action potential towards body wall, body cavity, or organ. It is also an efferent nerve fibre.</p> Signup and view all the answers

What is the sensory function in a nerve fibre?

<p>Action potential towards the brain. It is also called an afferent nerve fibre.</p> Signup and view all the answers

What is the outermost layer of the cerebral hemisphere?

<p>It is called the cortex. It consists of gyri and sulci.</p> Signup and view all the answers

What is the gyri and the sulci?

<p>Gyrus- raised convex ridge Sulcus- fissure (depression)</p> Signup and view all the answers

What are the four lobes of a cerebral hemisphere?

<p>Frontal, parietal, temporal and occipital lobes. They are named after the cranial bones.</p> Signup and view all the answers

What is the spinal cord? What are its functions?

<p>The spinal cord is a cylindrical structure that runs through the center of the spine, from the brainstem to the lower back.</p> <ol> <li>Control body movements and functions</li> <li>Report senses to your brain</li> <li>Manage your reflexes</li> </ol> Signup and view all the answers

Where does the spinal cord pass through?

<p>It passes through the foramen magnum and it is protected by the vertebral canal.</p> Signup and view all the answers

What are the four segments of the spinal cord?

<ol> <li>Cervical</li> <li>Thoracic</li> <li>Lumbar</li> <li>Sacral/ coccygeal</li> </ol> Signup and view all the answers

What are the spinal enlargements?

<p>The widened area of the spinal cord that gives attachment to the nerves which supply the lower limbs. There are two enlargements- cervical and lumbosacral.</p> Signup and view all the answers

What is the conus medullaris?

<p>The spinal cord in the adult vertebrae ends at the L1/L2 Intervertebral disc level. The point at which it ends is the conus medullaris.</p> Signup and view all the answers

What is the cauda equina?

<p>The lumbar and sacral spinal nerve roots descend in the vertebral canal to exit from the appropriate intervertebral foraminae. It forms a collection of nerve fibres towards the bottom of the spinal cord which forms the cauda equina (it looks like a horse's tail).</p> Signup and view all the answers

What is the CN 1, modality, function, point of connection to CNS, route through and exit from cranium?

<p>CN1- olfactory nerve- sensory (special)- smell- originates from the cerebrum, passes through the cribriform plate of the ethmoid bone in the anterior cranial fossa.</p> Signup and view all the answers

What is the CN 2, modality, function, point of connection to CNS, route through and exit from cranium?

<p>Optic nerve, sensory (special), connects to the cerebrum, route through the optic canal in the middle cranial fossa</p> Signup and view all the answers

What is the CN 3, modality, function, point of connection to CNS, route through and exit from cranium?

<ol> <li>Oculomotor nerve 2) motor function 3) Connects to the midbrain pontine region in the brain 4) Controls the eye muscles and pupillary sphincter etc</li> <li>It has a somatic and parasympathetic function.</li> <li>Route through superior orbital fissure in the middle cranial fossa</li> </ol> Signup and view all the answers

What is the CN 4, modality, function, point of connection to CNS, route through and exit from cranium?

<ol> <li>Trochlear nerve</li> <li>Motor nerve (Somatic)</li> <li>Connects to the midbrain</li> <li>Route through the superior orbital fissure in the middle cranial fossa</li> </ol> Signup and view all the answers

What is the CN 5, modality, function, point of connection to CNS, route through and exit from cranium?

<ol> <li>Trigeminal nerve</li> <li>Sensory and motor function to the facial muscles</li> <li>Connects to the pons in the brain</li> <li>The CN V 1 passes through the superior orbital fissure.</li> <li>The CN V 2 passes through the foramen rotunda.</li> <li>The CN V 3 passes through the foramen ovale</li> <li>The Vth cranial nerve passes through the middle cranial fossa</li> </ol> Signup and view all the answers

What is the function of the trigeminal nerve (5th cranial nerve)

<p>The trigeminal nerve primarily helps you feel (sensory), although the mandibular nerve branch has both sensory and motor functions. The trigeminal nerve helps with:</p> <ol> <li>Biting, chewing and swallowing.</li> <li>Facial and scalp sensations.</li> </ol> Signup and view all the answers

What is the CN 6, modality, function, point of connection to CNS, route through and exit from cranium?

<ol> <li>Abducent nerve</li> <li>Motor nerve (somatic)</li> <li>Abductive movement of the eyes</li> <li>Passes through the superior orbital fissure in the medial cranial fossa</li> </ol> Signup and view all the answers

What are the three parts of the 5th cranial nerve (trigeminal nerve)?

<ol> <li>Ophthalmic nerve passes through the superior orbital fissure. It is a sensory nerve connecting to the scalp, forehead and nose.</li> <li>Maxillary nerve passes through the foramen rotundum. It is a sensory nerve connecting cheeks, upper lip and palate.</li> <li>Mandibular nerve passes through the foramen ovale in the medial cranial fossa. It is sensory and motor in nature. Sensory- connecting to the tongue, skin over mandible. Motor- muscles of mastication.</li> </ol> Signup and view all the answers

What is the CN 7, modality, function, point of connection to CNS, route through and exit from cranium?

<ol> <li>Facial nerve</li> <li>Special sensory, motor and parasympathetic function</li> <li>GSS- external ear sensation, SVS- taste from anterior tongue, palate, SVM- muscles of facial expression, GVM- submandibular, siblingual, lacrimal, mucous glands.</li> <li>Connects to the pontine medulla junction</li> <li>Passes through the internal acoustic meatus.</li> </ol> Signup and view all the answers

What is the CN 8, modality, function, point of connection to CNS, route through and exit from cranium?

<ol> <li>Vestibulocochlear nerve</li> <li>Sensory nerve</li> <li>Responsible for hearing and balance</li> <li>Connects to the pontine medulla junction in the posterior cranial fossa</li> </ol> Signup and view all the answers

What is the CN 7, modality, function, point of connection to CNS, route through and exit from cranium?

<ol> <li>Facial nerve 2) Special sensory, motor and parasympathetic function 3) GSS- external ear sensation, SVS- taste from anterior tongue, palate, SVM- muscles of facial expression, GVM- submandibular, siblingual, lacrimal, mucous glands. 3) Connects to the pontine medulla junction 4) Passes through the internal acoustic meatus in the posterior cranial fossa</li> </ol> Signup and view all the answers

What is the CN 9, modality, function, point of connection to CNS, route through and exit from cranium?

<ol> <li>Glossopharyngeal nerve</li> <li>Special sensory and Motor functions</li> <li>GSS: post. 1/3 tongue, ext. ear, and middle ear cavity. GVS: carotid body and sinus. SVS: taste from posterior 1/3 tongue. GVM: parotid gland. SVM: stylopharyngeus</li> <li>Connects to the medulla oblongata in the brain</li> <li>Passes through the jugular foramen in the posterior cranial fossa</li> </ol> Signup and view all the answers

What is the CN 10, modality, function, point of connection to CNS, route through and exit from cranium?

<ol> <li>Vagus nerve 2) Sensory, motor and parasympathetic 3) GSS: ext. ear, larynx and pharynx. GVS: larynx, pharynx and, thoracic &amp; abdominal viscera. SVS: taste from epiglottis region of tongue. GVM: smooth muscles of pharynx, larynx and most of the GIT. SVM: most muscles of pharynx and larynx. 4) Connects to the medulla oblongata 5) Passes through the jugular foramen in the posterior cranial fossa</li> </ol> Signup and view all the answers

What is the CN 11, modality, function, point of connection to CNS, route through and exit from cranium?

<ol> <li>Spinal accessory</li> <li>Motor function</li> <li>GSM: trapezius and sternocleidomastoid. SVM: a few fibres run with CNX to viscera.</li> <li>Connects to the medulla oblongata</li> <li>Passes through the jugular foramen in the posterior cranial fossa</li> </ol> Signup and view all the answers

What is the CN 12, modality, function, point of connection to CNS, route through and exit from cranium?

<ol> <li>Hypoglossal nerve</li> <li>Motor function</li> <li>Intrinsic and extrinsic tongue muscles (except the palatoglossus)</li> <li>Connects to the medulla oblongata</li> <li>Passes through the hypoglossal canal in the posterior cranial fossa.</li> </ol> Signup and view all the answers

What is the nomenclature of the spinal nerves?

<p>The spinal nerve is named after the vertebrae above it, except for cervical region where they are named according to the vertebrae below (C8 exits between C7 and T1 vertebrae).</p> Signup and view all the answers

Why is the nomenclature of the cervical spinal nerves different?

<p>In the cervical region, the nerves are named according to the vertebrae below it. The C1 spinal nerve is attached above the C1 vertebrae which allows it to be named like that. The C8 spinal nerve exits between the C7 and T1 vertebrae.</p> Signup and view all the answers

Which part of the body do the spinal nerves supply?

<p>Soma (body wall)</p> Signup and view all the answers

Where are spinal nerves located?

<p>Located only within the intervertebral foraminae</p> Signup and view all the answers

How do the spinal nerves connect to the soma and the spinal cord

<ol> <li>The spinal nerves from the intervertebral foramina connects with the structures of the soma via the rami on one side 2) On the other side, it connects to the spinal cord via the roots and rootlets.</li> </ol> Signup and view all the answers

Which parts of the body do the posterior and anterior rami supply?

<ol> <li>The anterior/ventral ramus innervates the skin and muscle on the anterior aspect of the trunk.</li> <li>The posterior/dorsal ramus innervates the post-vertebral muscles and the skin of the back.</li> </ol> Signup and view all the answers

Which part of the spinal nerves form the cervical plexus? Which parts of the body do they supply?

<p>C1-C4 anterior rami, supplies the posterior scalp, neck wall, diaphragm</p> Signup and view all the answers

Which part of the spinal nerves form the brachial plexus? Which parts of the body do they supply?

<p>C5- T1 anterior rami, supplies the upper limb</p> Signup and view all the answers

Which part of the spinal nerves form the lumbar plexus? Which parts of the body do they supply?

<p>L1-L4 anterior rami, supplies the lower limb</p> Signup and view all the answers

Which part of the spinal nerves form the sacral plexus? Which parts of the body do they supply?

<p>L5-S4 anterior rami &amp; supplies the lower limb, gluteal region and perineum</p> Signup and view all the answers

How does the anterior rami supply the limbs?

<p>Supply all the limbs via plexus- networks of intertwined anterior rami</p> Signup and view all the answers

What is a dermatome? What is the exception to it?

<ul> <li>Area of skin supplied by both the anterior and posterior rami of a spinal nerve -Exception - limbs (no posterior rami)</li> </ul> Signup and view all the answers

What is the T4 dermatome?

<p>Nipple</p> Signup and view all the answers

What is the T10 dermatome?

<p>Umbilicus</p> Signup and view all the answers

What does the soma include?

<ul> <li>Includes head and neck walls, chest walls, back, diaphragm, abdominal wall, pelvic wall, limbs</li> <li>Structures - skin, fascia, skeletal muscle, skeleton, internal lining of body cavities</li> </ul> Signup and view all the answers

What are the sensations from the mechanoreceptors?

<p>Coarse touch, fine touch, vibration and proprioception</p> Signup and view all the answers

What are the sensations from the thermoreceptors?

<p>Temperature</p> Signup and view all the answers

What are the sensations from the nociceptors?

<p>Pain</p> Signup and view all the answers

What kind of pain is (a) dull (b) sharp in nature?

<p>Dull pain is usually visceral. A sharp pain is usually somatic.</p> Signup and view all the answers

What is the somatic sensory pathway to the brain?

<p>Sensory receptors stimulated → anterior ramus → plexus according to region (e.g. lumbar) → posterior root ganglion → posterior roots → posterior rootlets → posterior horn → cross over midline and action potentials ascend towards brain</p> Signup and view all the answers

What is the motor innervation pathway to the skeletal muscle?

<p>Somatic motor axons cross over in brainstem then descend to anterior horn → anterior rootlets → anterior roots → spinal nerves → plexus → synapse onto skeletal muscle which contracts</p> Signup and view all the answers

What are the properties of spinal reflexes?

<ol> <li>Rapid - misses out pathways to brain</li> <li>Involuntary - protective function</li> <li>Signals do go to the brain to regulate power of flexion- otherwise it may cause an injury.</li> </ol> Signup and view all the answers

What does the autonomic nervous system include?

<p>Internal environment: includes viscera, glands, smooth and cardiac muscle and external lining of organs - Locations - internal organs in body cavities, body wall organs</p> Signup and view all the answers

What body wall organs are innervated by the autonomic nervous system?

<ol> <li>Sweat glands</li> <li>Arrector smooth muscles (connects hair follicles to the basement membrane- making hair stand)</li> <li>Arterioles</li> </ol> Signup and view all the answers

What is the role of the sensory neurons in the autonomic nervous system?

<p>Sense internal environment - heart rate, blood pressure, digestion, gland secretions.</p> Signup and view all the answers

What are the organ's sensory nerves called?

<p>Visceral afferent nerves</p> Signup and view all the answers

What are the sensations from the organs to the CNS through the autonomic nervous system?

<ol> <li>Touch</li> <li>Temperature</li> <li>Pain (ischaemic- due to loss of blood supply, colicky- pain comes and goes. It is describes a dull, achy, nauseating pain. It is poorly localised.</li> </ol> Signup and view all the answers

What is the role of motor neurons in the autonomic nervous system?

<p>Responds to the changes in internal environment</p> Signup and view all the answers

What are the functional subdivisions of the autonomic nervous system?

<p>It involves a dual motor control- sympathetic and parasympathetic functions. It can be looked at like an accelerator and brake function in the nervous system.</p> Signup and view all the answers

What is the sympathetic outflow pathway in the autonomic nervous system?

<ol> <li>Originates from autonomic centres in brain</li> <li>Passes down spinal cord</li> <li>Exits spinal cord with T1-L2 spinal nerves</li> <li>Travel to sympathetic chains running the length of vertebral column</li> <li>Pass into all spinal nerves <ol> <li>Anterior and posterior rami supply body wall structures</li> </ol> </li> <li>‘Hitch a ride’ with arteries to all head and neck organs and skin</li> <li>Travel via splanchnic nerves to reach organs</li> </ol> Signup and view all the answers

What is the role of the sympathetic division of the autonomic nervous system? Which body parts does it supply?

<ul> <li>Supplies all internal organs, body wall organs and arterioles</li> <li>‘Flight or fight’ response</li> </ul> Signup and view all the answers

What is the flight or flight response in the following organs?

  1. Pupils
  2. Heart
  3. Lungs
  4. GI tract
  5. Liver
  6. Adrenal glands
  7. Arterioles
  8. Skin

<ol> <li>Pupils- dilate</li> <li>Heart- rate increases</li> <li>Lungs- bronchioles dilate</li> <li>GI tract- motility is reduced</li> <li>Liver- glucose released into the blood</li> <li>Adrenal glands- adrenaline/ noradrenaline released</li> <li>Arterioles- dilate in skeletal muscle, constrict in skin</li> <li>Skin- hair stands on end and sweat is produced</li> </ol> Signup and view all the answers

What is the role of the parasympathetic division of the autonomic nervous system?

<ol> <li>Often supplies same internal organs as sympathetic division, does not supply body wall organs or arterioles</li> <li>‘Rest and digest’ response- returns to homeostasis, complements/ opposes the sympathetic system</li> </ol> Signup and view all the answers

What is the rest and digest response from the parasympathetic outflow in these organs?

  1. Pupils
  2. Heart
  3. Lungs
  4. GI tract
  5. Liver
  6. Bladder

<ol> <li>Pupils- constrict</li> <li>Heart- rate decreases</li> <li>Lungs- bronchioles constrict</li> <li>GI tract- motility is increased</li> <li>Liver- glucose synthesis</li> <li>Bladder- sphincter relaxes</li> </ol> Signup and view all the answers

What is the parasympathetic outflow pathway in the autonomic nervous system?

<ul> <li>All parasympathetic axons leave the CNS via cranial nerves III, VII, IX and X and via sacral spinal nerves</li> <li>Parasympathetic ganglia in head travels to lacrimal gland and salivary glands</li> <li>Vagus nerve supplies organs of the neck, chest and abdomen as far as the mid-gut</li> <li>Sacral spinal nerves ‘carry’ parasympathetic axons to the hindgut, pelvis and perineum</li> </ul> Signup and view all the answers

What is another name for the parasympathetic outflow in the autonomic nervous system?

<p>Craniosacral outflow</p> Signup and view all the answers

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