Intro to Nervous System

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

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.

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

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

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

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

<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

<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

<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

<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

<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

<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

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

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

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

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

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

<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

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

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

<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

<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

<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

<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

<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

<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

<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

<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

<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

<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

<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

<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

<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

<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

<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

<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

<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

<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

<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

<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

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

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

<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

<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

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

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

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

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

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

<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

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

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

<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

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

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

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

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

<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

<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

<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

<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

<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

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

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

<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

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

<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

<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

<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

<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

<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

<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

<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

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