Compendium 9 Notes PDF

Compendium 9 Notes Lecture 1 Spinal Cord 1 - The spinal cord extends inferiorly from the foramen magnum to the first or second lumber vertebrae - The spinal cord can be divided into the cervical, thoracic, lumbar, sacral and coccygeal regions - There are 31 pairs of spinal nerves...

Compendium 9 Notes Lecture 1 Spinal Cord 1 - The spinal cord extends inferiorly from the foramen magnum to the first or second lumber vertebrae - The spinal cord can be divided into the cervical, thoracic, lumbar, sacral and coccygeal regions - There are 31 pairs of spinal nerves that emerge from the spinal cord Spinal cord 2 - Cervical nerves 8 - Thoracic nerves 12 - Lumbar nerves 5 - Sacral nerves 5 - Coccygeal nerve 1 - The diameter of the spinal cord changes from top to bottom because - There are enlargements in the cervical region and the lumbar-sacral region - These enlargements correspond with the limbs cervical supplying the arms and lumbar/sacral supplying the legs - The pointed end of the spinal cord is called the conus medullaris - The cauda equina are the roots of the spinal cord Meninges 1 - Meninges: the connective tissue covering the spinal cord and brain - Functions: - Protect the CNS and its blood vessels - Contains the cerebrospinal fluid - Forms partitions in the skull Meninges 2 - Dura mater - Outermost, superficial and thickest meningeal layer - Surrounds the brain and the outer layer if the spinal nerves - Subdural space: the space between the dura mater and the next layer of meninges containing serous fluid - Arachnoid mater - Looks like cobwebs - Deep to the arachnoid mater is the subarachnoid space containing blood vessels and cerebrospinal fluid - Pia mater - A gentle or tender layer that is the last or most deep layer of meninges - Has many blood vessels in it - Sits tightly over the spinal cord and brain Spinal cord 3 (mostly covered last compendium) CNS PNS Brain Spinal cord -------------- ---------------------------- ---------- -------------- ------------- Grey matter Cortex of brain and nuclei Ganglion Outer cortex Inner White matter Nerve tracts Nerves Deeper Outer - The spinal cord's white matter can be divided into a dorsal, ventral, anterior and lateral column - The spinal cord's grey matter can be divided into a posterior, lateral and anterior ventral horns - The spinal cord has commissures - Rootlets merge to form dorsal and ventral roots which merge to form a spinal nerve - The central canal is in the centre of the grey matter Organisation of neurons in the spinal cord 1 (mostly covered last compendium) - Sensory nerves travel through the dorsal roots - Motor (somatic and autonomic) neurons travel through the ventral roots Organisation of neurons in the spinal cord 2 (mostly covered last compendium) - Cell bodies of motor neurons are in the horns of the grey matter - Autonomic neuron cell bodies are found in the lateral horn - The somatic motor neuron cell bodies are found in the lateral horn Nerve - Endoneurium - Surrounds each axon and its associated Schwann cells - Nerve fascicle - A bunch of axons surrounded by endoneurium - Perineurium - Surrounds a group of axons or a nerve fascicle - It is a more coarse connective tissue than the endoneurium - Epineurium - Surrounds a group of fascicles - A nerve or a spinal nerve The organisation of spinal nerves Spinal nerves Vertebral bones ----------- --------------- ------------------------ Cervical 8 pairs 7 bones Thoracic 12 pairs 12 bones Lumbar 5 pairs 5 bones Sacral 5 pairs 5 bones Coccygeal 1 pair 5 fused bones = 1 bone - 31 spinal nerves but 30 spinal bones - C1 comes out of the top of the first vertebrae causing the difference in nerves to bones (diagram might help) Lecture 2 The brain 1 - Jelly like mass - Weighs 1.5kg - One of the biggest and most complex organs in the body - The brain is made up of approximately 100billion neurons and a trillion neuroglial cells - The brain is made up of: - The forebrain - Cerebrum - Diencephalon - The midbrain - The hindbrain - Pons - Medulla oblongata - Cerebellum - The midbrain, pons and medulla oblongata form what is referred to as the brain stem The brain stem - The brain stem sits under the diencephalon - The brain stem connects the spinal cord to the rest of the brain - The midbrain, pons and medulla oblongata form what is referred to as the brain stem Medulla oblongata - The medulla oblongata connects directly to the spinal cord - It connects at the level of the foramen magnum - It is an autonomic reflex centre maintaining homeostasis in the body - Contains the cardiovascular centre - Regulates heart rate, force of heart contraction and blood vessel diameter - Contains the respiratory centre - Regulates the rate and depth of breathing - Other reflexes - Swallowing, vomiting, hiccupping, coughing and sneezing - All of these functions are automatic and require no thought Pons - A bulging structure of the brain stem - Pons is the Latin word for bridge - The pons bridges different parts of the brain - Contains conduction tracts which run in two directions - The longitudinal tracts run from the spinal cord to higher brain centres - The transverse tracts run from the cerebrum (motor cortex) to the cerebellum - The pons contains a sleep centre which regulates rapid eye movement which is something that occurs during sleep - The pons has a respiratory centre which works together with the respiratory centre of the medulla oblongata to regulate respiration Midbrain - The smallest and most superior part of the brain stem - Receives visual, auditory and tactile sensory input generating reflex movements of the head, eyes and body - Eye movement relates to dilation and constriction of the pupil or a change in the shape of the lens Cerebellum - A cauliflower like structure - Sits in the inferior, posterior part of the brain - The cerebellum has an outer cortex made up of grey matter and an inner medulla made up of white matter - The cerebellum is much smaller than the cerebrum - The cerebellum controls locomotion in association with the cerebrum - Walking, running, skipping, ect. - Regulates fine motor control - Writing, using a computer or playing a musical instrument - Controls posture and balance Diencephalon - Made up of the: - Thalamus - The largest part of the diencephalon - Sensory relay centre or "gateway" - Anything you har, see or feel by touch but not smell - Regulates mood, memory and strong emotions like fear and rage - Subthalamus - The area underneath the thalamus - Epithalamus - Made up of the habenula and the pineal gland - Posterior to the thalamus - Hypothalamus - Below the Thalamus - Maintains homeostasis via the endocrine system - Regulates heart rate - Regulates digestive activities (food intake, water balance and thirst) - Controls muscles in swallowing - Controls body temperature by promoting sweating and shivering - Regulates sex drive and sexual pleasure - Regulates mood, and emotions - Regulates the sleep-wake cycle Cerebrum - Takes up most of the mass of the brain - Most superficial and superior part of the brain - Gyri -- elevated tissue or folds - Sulci -- grooves - Fissures -- deep grooves - The brain can be divided into right and left hemispheres which are divided by the longitudinal fissure - The lateral fissure separates the temporal lobe from the rest of the cerebrum - The central sulcus separates the frontal lobe from the parietal lobe - Lobes - Frontal - Parietal - Occipital - Temporal - Insula Cerebrum 2 - Precentral gyrus -- primary somatic motor cortex - Controls voluntary movements in the body, particularly fine motor movements of the hand - Uses skeletal muscle for activities requiring hands or fingers such as picking things up with the fingers - Located just in front of the central sulcus and is a part of the frontal lobe - Postcentral gyrus -- primary somatic sensory cortex (AKA primary somatosensory cortex) - This part of the brain receives messages from the somatic sensory receptors in skeletal muscle joints and tendons - These sensations are processed in this area e.g. pain, pressure or temperature - The signals first synapse in the thalamus before going to the postcentral gyrus - Part of the parietal lobe - Frontal lobe - Voluntary motor function - Motivation - Planning - Aggression - Sense of smell - Regulation of emotional behaviour and mood - Parietal lobe - Area which receives most of the sensory input - Does not receive smell, hearing, taste or vision Cerebrum 3 - Occipital lobe - Receives and processes visual input - Temporal role - Receives and processes smell and hearing and also has a role in memory - Insula - Receives and processes taste information Cerebrum 4 - The grey matter of the cerebrum makes up the cerebral cortex - Cell bodies, dendrites, unmyelinated axons, axon terminals and neuroglial cells - This is where consciousness is formed, it allows us to communicate, remember, understand things and be aware of ourselves and any sort of sensations - The white matter is deep to the cerebral cortex and is known as the cerebral medulla - This is made up of myelinated axons - This part of the brain is responsible for communication between cerebral areas and lower nervous system centres e.g. cardiovascular centre , sleep centre, respiratory centre - Corpus callosum - A bundle of fibres known as the commissural fibres - Connects the two cerebral hemispheres together - This ensures the brain all works as one Limbic system - The limbic system runs through the medial aspect of the left and right cerebral hemispheres as well as the diencephalon - Runs around the boarder of the corpus callosum and diencephalon - The limbic system has a role in memory and is referred to as the emotional brain - Expresses emotions though gestures - If you smell a particular smell it could trigger an emotional response or a memory - Damage to the limbic system can cause memory impairment Meninges - Dura mater - Fibrous connective tissue - Periosteal dura - The most superficial meningeal layer which attaches to the inner surface of the bony skull - Meningeal dura - A fine membrane sitting inferior to the periosteal layer - This is continuous with the dura mater of the spinal cord - In some parts of the brain there is a space between the periosteal dura and the meningeal dura, the space is referred to as Dural venous sinus - This cavity contains veins which collect blood that has just nourished the brain and will return to the heart (venous blood) - Dural folds are connective tissue partitions that extend deep into the brain which help hold the brain in place and stop excessive movement of the brain - In some parts the periosteal and meningeal dura fuse together, the Dural venous sinus doesn't exist in all parts of the brain - The subdural space contains serous fluid - Arachnoid mater - In the spinal cord this layer is thin, flimsy and fine, like cobwebs. It is similar in the brain - Underneath the arachnoid mater is sub arachnoid space containing cerebrospinal fluid and blood vessels - Pia mater - The deepest meningeal layer - A delicate connective tissue layer containing small blood vessels - This layer sits tightly over the brain and is not removable Ventricles - This word normally means a cavity or chamber such as the ventricles of the heart - The brain has for ventricles which are continuous with each other - The ventricles are lines with ependymal cells - The largest ventricles are the lateral ventricles of the brain. They extend into the cerebral hemispheres (these paired lateral ventricles are considered the first and second ventricle) - The lateral ventricles are continuous with the third ventricle which resembles the head of a bird from a lateral view - The third ventricle is continuous with the fourth ventricle which is located in the brain stem and is continuous with the central canal of the spinal cord Cerebrospinal fluid - Most cerebrospinal fluid is produced by the choroid plexus - The choroid plexus in the brain is made up of specialised ependymal cells, support tissue and blood vessels - Cerebrospinal fluid is a fluid that is found around the brain and spinal cord - The role of cerebrospinal fluid is to protect the brain and spinal cord from trauma and it provides buoyancy to the brain (the brain floats rather than sitting directly on the skull) which reduces the weight of the brain reducing the pressure on structures under the brain - The composition of CSF is similar to the blood plasma but contains less proteins and has a different ionic concentration - The CSF circulates the ventricles and the central canal of the spinal cord as well as the subarachnoid space of the meninges - The cilia of the endymal cells of the ventricles help with the circulation flow Cranial nerves - There are 12 pairs of cranial nerves all named after roman numerals - Cranial nerves emerge directly out of the brain and carry information from the brain to the body and back to the brain - Cranial nerves can be either single or mixed neurons meaning that they either have a just a sensory function, a somatic function or a parasympathetic function or a combination of all 3 Lecture 3 Functional divisions of the nervous system - Autonomic nervous system - Motor (efferent) - Sympathetic - Parasympathetic - Sensory (afferent) - Somatic nervous system - Motor (efferent) - Sensory (afferent) Autonomic vs somatic nervous system Somatic nervous system Autonomic nervous system --------------------------- -------------------------------------------------------------------- ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Effector Skeletal muscle Cardiac muscle, smooth muscle and glands Regulation Controls all conscious and unconscious movement of skeletal muscle Unconscious regulation although conscious thought has an influence Response to stimulation Skeletal muscle contracts Target tissues are stimulated or inhibited Neuron arrangement One neuron extends from the CNS to the skeletal muscle There are two neurons in series; a preganglionic neuron runs from the CNS to an autonomic ganglion and the postganglionic neuron runs from the ganglion to the effector (target tissue) Neuron cell body location Located in the ventral horn of the spinal cord Located in the lateral horn of the spinal cord and autonomic ganglion Number of synapses 1 (motor neuron -\> skeletal muscle) 2 (neuron to neuron then neuron to target tissue) Sympathetic and parasympathetic - Sympathetic ('fight or flight') - Stimulated in a threatening or exciting situation - May cause deeper breathing, increased heart rate, decreased or halted digestion (this is because blood moves away from the digestive system and towards the muscles), relaxation of the urinary bladder - AKA the 'E' division as it is stimulated during exercise, excitement, emergency or embarrassment - Parasympathetic ('rest and digest') - This is activated in order to keep the bodies energy usage as low as possible (energy preservation) - This activates digestion, salivation, formation of tears, elimination of faeces and urine - AKA the 'D' division as it is stimulated during digestion, defecation and diuresis (urination) - These responses can serve the same organs but in doing so serve them in opposing ways Sympathetic Parasympathetic -------------------------------------------------- -------------------------------------------------------------------- --------------------------------------------------------- Heart rate and blood pressure Increased Decreased Airways in the lungs Dilation Constriction Blood vessels Mainly constriction but vasodilation to skeletal muscles No effect Digestive tract Decreased motility and decreased secretion, constricted sphincters Increased motility and secretion, sphincters will relax Liver Increased glucose released into blood Gall bladder Glands (salivary, gastric, lacrimal, pancreatic) Sweat glands Pupil of the eye Cellular metabolism Urinary bladder Anatomy of the automatic nervous system - The autonomic nervous system is a two neuron system - The cell bodies are located in the lateral horn of the spinal cord and the autonomic ganglion - The location of the cell bodies along the length of the spinal cord is different for sympathetic and parasympathetic divisions - Sympathetic: the cell bodies are found between T1 and L2 (the thoracolumbar division) - Parasympathetic: the cell bodies are found between S2 to S4 and cranial nerve nuclei (craniosacral division) Functional generalisations of the sympathetic and parasympathetic nervous systems - Dual innervation of the of the autonomic nervous system - Opposing effects - Responses generated by both afferent nervous system divisions can regulate - Heart rate - Blood pressure - Airways in the lungs - Digestive tract - Glands (salivary, gastric, lacrimal) - Pupil of the eye Regulation of the autonomic nervous system - Autonomic nervous system regulation occurs mostly via reflexes - Reflexes are an automatic response to a stimulus, and these are normally homeostatic - Autonomic reflex activity is also influenced by the CNS, in particular the cerebrum, hypothalamus, brain stem and a few other parts which control thoughts, actions and emotions - The hypothalamus integrates the information that's coming into it and communicates it to other parts of the brain to execute a response - Most autonomic reflexes actually involve a part of the Hypothalamus CNS Component Effect on the ANS ---------------------------- -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Spinal cord Autonomic reflex centre which regulates defecation, urination, erection and ejaculation Brainstem Reflex centre controls tear production , salivation, coughing, swallowing, digestive activities, heart rate and force of contraction, blood vessel diameter and respiration Hypothalamus Integrates the incoming information from the brainstem and the spinal cord and relays any info that goes to higher centres of the brain such as the cerebrum and limbic system Cerebrum and limbic system Thoughts and emotions can influence ANS functions through the hypothalamus e.g. if angry your blood pressure might increase, if you think about your favourite food you may salivate Tutorial notes Station 1a 1. - Connective tissue 2. - Organisation 3. - Endoneurium - Perineurium - Epineurium 4. - The central nervous system already has a lot of protective layers (bone and meninges) so it doesn't require the extra protection 5. - Endoneurium: surrounds the axon - Perineurium: surrounds groups of axons (nerve fascicles) - Epineurium: surrounds groups of nerve fascicles 6. - Maybe blood vessels (veins) Station 1b 1. 8 7 ---- ------------------- 12 12 5 5 5 5 1 5 fused bones = 1 31 30 2. 3. 4. 5. 6. 7. 1. - Mid brain - Pons - Medulla 2. +-----------------------------------+-----------------------------------+ | Midbrain | Receives auditory, visual and | | | tactile sensory information and | | | generates reflexes from the head, | | | eyes and body | | | | | | Also controls pupil dilation and | | | lens shape | +===================================+===================================+ | Pons | Contains a sleep centre and | | | connects lots of different parts | | | of the brain | +-----------------------------------+-----------------------------------+ | Medulla | An autonomic reflex centre which | | | aids homeostasis of the body | | | | | | Respiration, circulation and | | | other reflexes like hiccups | +-----------------------------------+-----------------------------------+ 3. - Because it is mostly controlled by the medulla oblongata Diencephalon 1. - White matter 2. - Thalamus - Subthalamus - Epithalamus - Hypothalamus 3. - The hypothalamus works in conjunction with the endocrine system to maintain homeostasis in the body 4. - Labelled 5. - The pituitary gland 6. - Yes, homeostasis would be hugely disrupted as the hypothalamus plays a very significant role in body homeostasis Station 2b 1. - The vermis is the part of the frontal cortex which connects the two hemispheres of the brain 2. - Its not really convoluted, but it has lots of branches, they are similar but not the same 3. - Coordination of fine motor movements 4. - In the spinal cord the white matter is on the outside and the grey matter is on the inside, in the brain the white matter is on the inside with the grey matter on the outside - The grey matter consists of cell bodies while the white matter consists of myelinated axons Case study 1 - Motor function - Somatic sensory info - Input of hearing and memory - The temporal lobe was operated on as the hippocampus s located deep to the temporal lobe - Short term memory is mostly stored in the temporal lobe but the long term memory is distributed all over the brain - Muscle memory is related to learning new skills Case study 2 Summery: Phineas Gage was a railroad worker and in an work related incident had a 6kg meter long pole blasted through his head passing from under his cheekbone and exiting the top of his cranium just posterior to his hairline 1. The rod would have passed through his frontal lobe 2. He survived as the more crucial parts of the brain are located in the hind brain/brainstem 3. a. Voluntary motor function b. Motivation c. Planning d. Aggression e. Sense of smell f. Regulation of emotional behaviour and mood 4. The hypothalamus also plays a role in regulating mood and emotions - Controlled by the limbic system and hippocampus which were preserved Case study 3 - Cerebellum - Testing for fine motor skills, coordination and whether the patient cen judge the distance to the target - The failure of the organ to develop properly