Dorsal cavity (brain and spine) PDF

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Dorsal cavities

3 LAYERS OF MENINGES LINING THE CRANIAL CAVITY o    o 

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CNS covered by 3 layers of fibrous tissue called MENINGES (underneath bony protection)( dense irregular connective tissues) Dura mater (tough outer layer) (connects to bone -periosteal) (connects to arachnoid – meningeal) Arachnoid mater (middle suspension layer) (webs that connects dura to pia, contains csf) Pia mater (delicate inner layer) (covers tissue itself) Meninges Divide the brain Hemispheres and compartments : dura mata folds on itself and creates separation). These Folds include - Felix cerebi: between right and left hemisphere (dura mata) - Tentorium cerebelli: between cerebellum and occipital lobe (dura mata) - Falx cerebelli: seperates right and left cerebellar hemisphere (dura mata) Stabilizes brain Provides venous sinuses to drain blood (duramata has is full of deoxygenated blood) (dural sinuses (holes) drain csf and blood)

STRUCTURES AND

REGIONS OF THE BRAIN  

Brainstem Conn cts sp nal c rd to hala us and

contains cranial nerves Inferior Medulla oblongata  Integration of breathing and swallowing, control of respiration, bp and cortical arousal (central nerves 2-4) o Middle Pons  Contains descending motor tract, (central nerves 5-8)  Relay information from cochlear and vestibule apparatus  Control of movement and sensation from the face , control of mastication/chewing o Superior Midbrain  Roles in movement , sensation , startle reflex (central nerves 8-12)  Visual and auditory reflexes , also orienting reflexes Cerebellum  Coordination of movement (contains half the neurons in the brain , very dense Diencephalon o Basal ganglia  A group of 5 interconnected nuclei buried deep to the cortex o Thalamus  receives input from all areas of the nervous system and distributes it o Hypothalamus  Controls hunger, thirst, sexual feelings, hormone and temperature regulation (basically, it regulates body homeostasis) (survival response) o

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Dorsal cavities  controls ANS function / integration (autonomic nervous system)  Influenced by frontal cortex and limbic cortex

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Brain hemispheres o Left and right Lobes o Frontal: motor/ movement functions o Parietal: somatosensory / touch o Occipital: vision o Temporal: hearing/memory Sulci : divide cerebrum into lobes o Non-specific

o Lateral sulcus: divide temporal lobe o Central sulcus: divide precentral and post central gyrus Gyri (Brain is folded inwards producing ridges of cortex = GYRI (single = gyrus) o Non-specific o Post central gyrus ( touch and pressure (parietal lobe) o Pre-central gyrus ( primary motor cortex > frontal lobe)

Dorsal cavities  Longitudinal fissure = lateral sulcus          Corpus callosum

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Largest commercial fibre : white matter that connects left and right hemisphere

Primary motor cortex  Last place motor information travels before it leaves brain (contralateral information)  Voluntary movement : Sends output to all muscles below the head on contralateral body  Pre-central gyrus Primary somatosensory cortex  Post central gyrus : Receives input from sensory receptors all over contralateral body Visual cortex  Receives input from both eyes about contralateral visual hemifield (Visuotopically arranged) Auditory cortex  Receives input from both ears, hearing, tonotopically arranged

Dorsal cavities  Ventricles:  Gaps in the brain that contain the cerebrospinal fluid (Provide buoyance and protection in subarachnoid space and is reabsorbed into venous circulation by arachnoid villi) o Lateral ventricles : in left and right hemisphere o Third ventricle : between two lobes of diencephalon, continuous with lateral ventricles and drains into fourth ventricle via the cerebral aqueduct (small canal that passes through midbrain of brainstem) o Fourth ventricle: between pons and cerebellum , continuous with spinal chord o Intraventricular foramen connects all three ventricles  Cerebrospinal fluid : flow in sub arachnoid space , protects brain by cushioning it , maintaining temp, removing waste , increasing buoyancy.

Vertebral Column

Dorsal cavities  Cervical  Thoracic  Lumbar  Sacral  structures on the articulated vertebral column: o Intervertebral foramina : foramen between two spinal vertebrae  Spinal nerves and arterys in and out of spinal cavity o Sacral foramina : sacral nerves exit here o Vertebral canal :contains spinal chord Spinal cord 

Extends as far as the L2 vertebra, beyond It runs at nerves (not at coccyx)

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White matter= myelinated axon Grey matter = unlyelinated cell bodies Horns (grey matter) o Ventral / anterior = wider ; (somatic motor nerve roots, skeletal muscles ) o Dorsal / posterior = longer and thinner (somatic / visceral sensory)  Lateral = visceral motor ( only present from first thoracic to lumbar) Rootlets : Because the spinal cord ends at vertebral level L1-L2 and is therefore shorter than the vertebral column. However, the spinal nerves arising from the lumbar and sacral spinal cord still need to exit the vertebral column from the intervertebral foramina in the lumbar and spinal vertebral column, so the rootlets will increase in length between the spinal cord segment and the relevant intervertebral foramen so that the spinal nerve exits at the correct place. Roots Ganglia ( on posterior root) Spinal nerves Dura Arachnoid Conus medullaris : end of the spinal chord Filum terminale : gathered spinal pia at the first and 2 nd lumbar vertebrae Cauda equina : bundle of spinal roots that extend inferior to conus medullaris Cervical enlargement : ½ Bulge Lumbar enlargement: 2/2 bulge -

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Dorsal cavities

Cranial nerves ( 11 out of 12 go through brain stem)            

I Olfactory: sensory; smell II Optic: sensory ; sight III Oculomotor: Motor ; eye movement IV Trochlear: motor ; eye movement V Trigeminal: Both ; sensory to the skin of face, motor to muscles of mastication VI Abducent: motor ; eye movement VII Facial: both ; -Sensory to tongue and mouth, motor to muscles of facial expression, facial gland secretion VIII Vestibulocochlear: Sensory : Sense of hearing and balance IX Glossopharangeal: Both : Sensory to tongue and pharynx, motor to muscles of swallowing, parotid gland secretion X Vagus : both ; Sense of taste, motor muscles for speaking and swallowing, motor to smooth muscle of visceral organs XI Accessory : Motor ; Motor to trapezius and sternocleidomastoid XII Hypoglossal: Motor ; -Motor to tongue muscles...