University of Central Lancashire Neuroscience Past Paper PDF

7th January 2025 XY3291 - Neuroscience Constantin-Iulian Chiță Where opportunity creates success  Gross anatomy of the CNS Where opportunity creates success Learning objectives Identify gross anatomical features of the brain and cord, meningeal layers and blood supply....

7th January 2025 XY3291 - Neuroscience Constantin-Iulian Chiță Where opportunity creates success  Gross anatomy of the CNS Where opportunity creates success Learning objectives Identify gross anatomical features of the brain and cord, meningeal layers and blood supply. Describe the blood vessels of the brain and the territories supplied by each Describe the formation, circulation and absorption of cerebrospinal fluid Understand the most prevalent neurovascular diseases Contents ❖ Research methods to study brain anatomy ❖Anatomical references ❖ Spinal cord ❖ Brain The meninges Ventricular system Blood supply the brain Brainstem Cerebellum Forebrain ❖ Neurovascular diseases Recap Time Reviewing the peripheral nervous system Autonomic nervous system Somatic nervous system Autonomic vs Somatic Nervous System Autonomic Nervous System - Regulates the involuntary movements in the body -> Innervates involuntary smooth muscles, glands, cardiac muscles - May cause excitatory or inhibitory responses - Contains sympathetic and parasympathetic nerves Somatic Nervous System - Regulates voluntary movements -> Innervates voluntary skeletal muscles - Always causes excitatory responses - Contains spinal and cranial nerves Central nervous system Spinal cord  The spinal cord Is involved in sensory processing, motor outflow, and reflexes Segmented: 8 cervical, 12 thoracic, 5 lumbar, 5 sacral, and 1 coccygeal. Each spinal cord segment innervates a dermatome All levels have a similar cross-sectional structure Grey matter - Central area - Cell bodies - Columns are functionally subdivided based on Rexed’s classification - Horizontal grey commissure (Area/Lamina X) White matter - Peripheral area - Myelinated axons - Subdivision: ❖anterior funiculus is limited medially by the ventral median sulcus, and laterally by the ventrolateral sulcus ❖lateral funiculus is limited ventrally and dorsally by the ventrolateral and dorsolateral sulci ❖posterior funiculus is located lateral to the dorsal median sulcus, and medial the dorsolateral sulcus Spinal Nerves They are mixed nerves that transmit both sensory (afferent) and motor (efferent) information Contain dorsal and ventral roots – The dorsal roots carry the information received from receptors towards the CNS – The ventral roots transmit the information from the CNS towards the effectors Important difference between the cell bodies of these neurons: The cell bodies of the dorsal root neurons are located in a dorsal/spinal root ganglion, whereas the cell bodies of the ventral root neurons are located in the grey matter of the spinal cord.  Spinal pathways Descending motor pathways 1. Pyramidal tracts Corticospinal tracts – supply the musculature of the body. Corticobulbar tracts – supply the musculature of the head and neck. 2. Extrapyramidal tracts Vestibulospinal Tracts – control balance and posture (ipsilateral) Reticulospinal Tracts – voluntary movements and muscle tone (ipsilateral) Rubrospinal Tracts – fine control of the hand movements (contralateral) Tectospinal Tracts – coordinates movements of the head in relation to vision stimuli (contralateral)  Ascending sensory pathways 1. Conscious tracts Dorsal column-medial lemniscal pathway – fine touch, vibration and proprioception Anterolateral system - Anterior spinothalamic tract – crude touch and pressure - Lateral spinothalamic tract – pain and temperature. 2. Unconscious tracts Spinocerebellar tracts – unconscious proprioceptive information Brain  The human brain weighs ~ 1400 g The brain of one of the earliest species linked to human evolution, Australopithecus afarensis, only weighted about 435 grams, and had a volume of approximately 400 cc. This is about 1/3rd of the size of the human brain nowadays. The growth is attributed to the addition of myelin and growth of neuronal processes, rather than the addition of more neurons  The meninges The three meninges, from the outermost layer inward, are the dura mater, the arachnoid mater, and the pia mater Dura mater - Provides Mechanical Strength - Contains Venous Sinuses That Drain the Brain - Has Its Own Blood Supply - Is Pain Sensitive  Arachnoid Mater -Bridges Over CNS Surface Irregularities, Forming Cisterns - Has a Barrier Function Pia Mater - Covers the Surface of the CNS Differences Between Cranial and Spinal Meninges 1. Cranial epidural space is a potential space in almost all parts of the skull, whereas spinal epidural space is an actual space. 2. Cranial epidural space, when present in pathological conditions, is located between periosteal dura and cranium. Spinal epidural space is located between periosteum and dura. This spinal epidural space is filled with fatty connective tissue and the external vertebral venous plexus.  Ventricular system 4 ventricles in the brain 1. Lateral ventricles - Located in each hemisphere - C-shaped course 2. Third ventricle - Is a Midline Cavity in the Diencephalon - 4 protrusions called recesses 3. Fourth Ventricle - Communicate with Subarachnoid Cisterns Choroid plexus Highly convoluted and vascular membranous material Functionally a three-layered membrane between blood and CSF Most of the CSF is produced within the ventricles by their choroid plexuses CSF functions→ mechanically supportive role, regulation of the extracellular environment of neurons and spatial buffering system Blood-brain barrier Control of cerebral blood flow: - Autoregulation - Collaborative local response - Innervation The barrier includes three regions of the CNS: 1. the arachnoid barrier layer 2. the blood–cerebrospinal fluid (CSF) barrier 3. rows of tight junctions between adjacent endothelial cells  Brain artery system Internal Carotid Arteries and Vertebral Arteries Supply the Brain 1. Internal Carotid Arteries Supply Most of the Cerebrum - ophthalmic artery - middle and anterior cerebral arteries - anterior choroidal and the posterior communicating artery 2. Vertebral-Basilar System Supplies the Brainstem and Parts of the Cerebrum and Spinal Cord - basilar artery - posterior spinal artery, anterior spinal artery, and posterior inferior cerebellar artery Cerebral Arterial Circle (Circle of Willis) posterior cerebral artery is connected to the internal carotid artery by the posterior communicating artery due to pressure differentials very little blood flows around this circle Brain vein system Divided in superficial and deep groups 1. Superficial Veins Empty Into the Superior Sagittal Sinus - superficial middle cerebral vein - superior anastomotic vein - inferior anastomotic vein 2. Deep Veins Empty Into the Straight Sinus - internal cerebral vein  Brainstem The spinal cord continues rostrally into the brainstem Functions: involved in heart rate, breathing, blood pressure, CNS regulation Three major subdivisions of the brainstem—medulla, pons, and midbrain  Medulla includes pyramids, olives, and part of the fourth ventricle Pons Includes the Basal Pons, Middle Cerebellar Peduncles, and Part of the Fourth Ventricle Midbrain Includes the Superior and Inferior Colliculi, the Cerebral Peduncles, and the Cerebral Aqueduct Cranial nerves  1. Somatic sensory fibers convey information from receptive endings for pain, temperature, and mechanical stimuli in somatic structures such as skin, muscles, and joints. 2. Visceral sensory fibers convey information from receptive endings in visceral structures such as the walls of blood vessels or of the digestive tract. 3. Visceral motor fibers are preganglionic autonomic axons. 4. Somatic motor fibers innervate skeletal muscle  Nerve Function 1. Olfactory Nerve Smell 2. Optic Nerve Vision – Visual Acuity 3. Oculomotor Nerve Pupil Constriction/Dilation, Visual Accommodation 4. Trochlear Nerve Vertical Eye Movements 5. Trigeminal Nerve Facial Sensation and Facial Movements 6. Abducens Nerve Lateral Movements of Eyeballs 7. Facial Nerve Taste, Facial Expressions 8. Vestibulocochlear Nerve Hearing + Balance 9. Glossopharyngeal Nerve Taste + Swallowing 10. Vagus Nerve Aortic Blood Pressure, Slows Heart Rate, Stimulates Digestive Organs 11. Accessory Nerve Controls Head and Shoulders Movements 12. Hypoglossal Nerve Tongue Movements  Cerebellum Cerebellum means “little brain” Processing of sensory information Involved in Motor Learning and cognitive functions Division into lobes – Anterior lobe (paleocerebellum) – Flocculonodular lobe (arhicerebellum) – Posterior lobe (neocerebellum) Division into zones – Vermix (involved in Postural Adjustments) – Lateral Hemisphere (Involved in Planning and Skilled Movements) – Medial Hemisphere (Involved in Adjusting Limb Movements) Attached to the brainstem by three peduncles on each side – Inferior cerebellar peduncle - composed mainly of afferent fibres to the cerebellum from the spinal cord and brainstem – Middle cerebellar peduncle - composed of only afferent fibres to the cerebellum from the pontine nuclei of the contralateral side – Superior cerebellar peduncle - contains the major efferent pathways from the cerebellum to the red nucleus and thalamus, as well as efferent fibres.  Cerebellar cortex Three-layered structure - Molecular layer, consisting mainly of the axons and dendrites of various cerebellar neurons - Purkinje layer, consisting of large neurons called Purkinje cells - Granular layer, composed mainly of small granule cells Afferent fibers to the cerebellar cortex: - Climbing fibers ends directly on each Purkinje cell - Mossy fibers end on the dendrites of granule cells  Cerebellar Cortex Receives Multiple Inputs 1. mossy fibers from the deep cerebellar nuclei 2. mossy fibers carry information from: - the vestibular nerve and nuclei to Flocculus and Vermis - the spinal cord to Vermis and Medial Hemisphere - the reticular formation - cerebral cortex (via pontine nuclei) to Vermis and Medial Hemisphere 3. climbing fiber input to the cerebellar cortex arises in the inferior olivary nucleus.  Cerebellar cortex outputs - is provided by axons of Purkinje cells 1. the vermis projects to the fastigial nucleus 2. the medial hemisphere projects to the interposed nucleus 3. lateral hemisphere projects to the dentate nucleus  Deep cerebellar nuclei Communicate with different parts of the brain and cerebellar cortex 4 pairs of nuclei: Fastigial, Dentate, Globose and Emboliform - Use glutamate as a neurotransmitter and make excitatory synapses Forebrain  Cerebral hemisphere Longitudinal fissure separates the forebrain in 2 hemisphere Folding into gyri and sulci Outer layer of grey matter- the cerebral cortex- and inner layer of white matter Corpus callosum interconnects the two cerebral hemispheres Four prominent sulci are used to divide each cerebral hemisphere into four lobes: 1. Frontal lobe 2. Parietal lobe 3. Temporal lobe 4. Occipital lobe Cerebral cortex - Cerebral cortex has a critical role in the abilities and activities that reach their highest level of development in humans - Pyramidal cells are the most numerous neocortical neurons - Neocortex has horizontal (six layers) and vertical organization  The neocortex of each cerebral hemisphere is made up of primary sensory areas, primary motor area, association areas - multimodal or heteromodal association areas- and limbic areas - Primary somatosensory cortex is in the parietal lobe - Primary visual cortex is in the occipital lobe - Primary auditory cortex is in the temporal lobe - Most motor areas are in the frontal lobe - Parietal association cortex mediates spatial orientation - Prefrontal cortex mediates working memory and decision making Basal nuclei - The basal nuclei include five major nuclei - The striatum and globus pallidus are the major components of the basal nuclei - Subthalamic nucleus and substantia nigra are interconnected with the striatum and globus pallidus Limbic system - Hippocampus and amygdala are the central components of the two major limbic subsystems - Limbic cortical areas and other limbic components serve as bridges between multimodal association areas - Amygdala is centrally involved in emotional responses - Hippocampus involved in memory and learning  Diencephalon Divided into four parts: - Epithalamus - includes the pineal gland habenular nuclei - Thalamus - Subthalamus – includes subthalamic nucleus and the zona incerta - Hypothalamus Interconnections between the cerebral cortex and subcortical structures travel through the internal capsule Thalamus - The thalamus is the gateway to the cerebral cortex - Has anterior, medial, and lateral divisions - Thalamic nuclei grouped by patterns of outputs and inputs: 1. Relay nuclei 2. Association nuclei 3. intralaminar and midline nuclei Hypothalamus - Controls the autonomic nervous system and coordinates drive- related behaviours - Hypothalamic inputs: 1. Afferents from the brainstem and spinal cord convey visceral and somatic sensory information 2. from limbic structures mediating many of the autonomic and somatic aspects of affective states - Hypothalamic outputs: 1. Endocrine control: magnocellular system, parvicellular system and by autonomic innervation of the endocrine glands 2. Behavioural control Neurovascular diseases  Cerebrovascular diseases→ restriction in flow of blood in the brain, or a part of the brain. experiences a 17 million deaths worldwide one-third of these deaths occur in middle-aged adults Classification – Ischemic and haemorrhagic strokes – Cerebral venous thrombosis – Aneurysms – Vascular malformations  Ischemic strokes Blood vessel becomes blocked (deprivation oxygen and glucose) ↓ CBF 20 mL/100 g/min – neuronal electrical activity starts to fail – release of excitatory amino acids – depletion of adenosine triphosphate – activation of proteolytic processes Cell survival is determined→ severity and duration of CBF reduction – central core→ may have irreversible cellular injury – the surrounding tissue (termed the penumbra)→ potentially salvageable if perfusion is restored Pathophysiology of ischemia 1. Thrombosis occlusion of a vessel Large-vessel disease – affect the major precerebral vessels→ carotid and vertebral arteries or circle of Willis – Atherosclerosis Small-vessel infarcts – basal ganglia, thalamus, brainstem, or cerebellum –