Nervous System Part 2 Flashcards
How much does the brain weigh?
It weighs 1/50 body weight
Where is the brain located?
In the cranial cavity
How much cardiac output is received by the brain?
15%
Approximately how much blood travels to the brain?
750ml
What 4 parts makes up the brain?
Cerebrum
Diencephalon
Brain stem
Cerebellum
What is the diencephalon composed of?
The thalamus and the hypothalamus
What is the brain stem composed of?
Midbrain
Pons
Medulla Oblongata
What is the largest part of the brain?
Cerebrum
What is the cerebrum divided into?
The right and left hemisphere
What part of the body does the right hemisphere control?
The left side of the body
What part of the body does the left hemisphere control?
Right hand side of the body
How is the cerebrum connected?
By white matter which is nerve fibres located deep in the brain
How is the brain composed in terms of white and grey matter?
It has white matter inside and grey matter that surrounds it.
How is the spinal cord composed in terms of white and grey matter?
The grey matter is on the inside and the white matter surrounds it.
What is the superficial layer of the cerebrum called?
Cerebral cortex made up of nerve cell bodies which is grey matter
What isa key characteristic of the cerebral cortex?
Has lots of folds (convolutions) separates by fissures which creates a greater surface area.
What lobes is the cerebrum divided into?
Frontal lobe
Parietal lobe
Occipital lobe
Temporal lobe
How many axons does the corpus callousness contain?
200 million axons
What is the purpose of the corpus callosum?
Interconnects the two hemispheres
What is the role of the corpus callosum?
Integrates motor, sensory and cognition between cerebral cortex on the right and left
What is the tentori cerebelli?
An extension of the dura mater that separates the cerebellum from the inferior portion of the occipital lobe.
What is the sulci in the brain?
A shallow groove in the brain that surrounds a gyrus
What is a fissure in the brain?
It is a large furrow/groove that divides the brain into lives and also into the two hemispheres as the longitudinal fissure
What is the gyrus in the brain?
A ridge on the cerebral cortex
What is the gyrus surrounded by?
Generally surrounded by one or more sulci (depressions or furrows; eg, sulcus)
What are the three main functions of the cerebral cortex?
Mental activities (association area/cortex)
Sensory perception (sensory area/cortex)
Initiation and control of voluntary movement (motor area/cortex)
What are some of the functions of the frontal lobe?
Attention span
Decision making
Inhibition
Planning
Judgement
Social
Sexual behaviour
What is the function of the temporal lobe?
Auditory perception
Words/speech
Memory association/formation
Emotions
Facial recognition
What are the functions of the parietal lobe?
Sensation and perception
Integrating sensory input, mainly visual
Cognition
Spatial awareness
Navigation
What is the function of the occipital lobe?
Visual processing
What is the role of the thalamus?
Relays sensory impulses to sensory cortex
Helps recall whether experience is pleasant or not
What is the role of hypothalamus?
Controls autonomic nervous system
Important in temperature regulation, water balance and metabolism
Also part of limbic system (emotions brain), pain/pleasure, libido (sexual pleasure), appetite/thrist
Regulates pituitary gland
How long is the brain stem?
3 inches
What tracts does the brain stem contain?
Ascending and descending tracts
Where is the midbrain located?
Inferior to cerebrum and superior to pons
What connects the cerebrum with lower parts of the brain and spinal cord?
The nuclei and nerve fibres in the brain stem
What does the nuclei do in the brain?
It relays ascending and descending nerve fibres
Where is the pons located? (3)
Anterior to the cerebellum
Inferior to midbrain
Superior to medulla Oblongata
What is the pons mostly composed of?
Nerve fibres
What is the purpose of the pons?
It connects the two hemispheres of the cerebellum and high levels of the brain with the spinal cord
What are some of the nuclei in the pons associated with?
Cranial nerves
What do other nuclei of the pons form?
Pneumotaxic and apneustic centres that operate the medulla Oblongata respiratory centre
Where is the medulla oblongata located? (2)
Inferior to the pons, continuous with the spinal cord
Just within cranium, inferior to the foramen magnum
How long is the medulla oblongata?
2.5cm
How is the medulla oblongata composed in terms of white and grey matter?
Grey matter centrally and white matter externally
What are the three vital centres associated with autonomic reflexes in the medulla oblongata?
Cardiovascular centre
Respiratory centre
Reflex centres - vomiting/coughing/sneezing/swallowing
What is controlled in the cardiovascular centre of the medulla?
Rate/force of contractions of heart
BP
What else is within the cardiovascular centre of the medulla?
Vasomotor centre
What is controlled by respiratory centre of the medulla?
Rate and depth
Nerve impulses going to phrenic and intercostal nerves - inspiration
Functions closely with pons
What is controlled in the reflex centres of the medulla?
Reflex actions
Like blinking of the eye due to stimulus of dust
Where do motor nerve travel down?
From the motor region of the cerebrum to spinal cord cross over in medulla called the decussation of pyramids.
Hence left hemisphere cerebrum controls right side etc
What is the cross over in the medulla called in the spinal cord?
Decussations of pyramids
Where are sensory nerves located?
Some of these nerve cross over in the medulla, whereas others cross over lower levels like the spinal cord
Where is the cerebellum located?
Inferior to posterior cerebrum, posterior to pons
What is the composition of the cerebellum?
Grey matter surface and white matter inner
What are the main functions of the cerebellum?
Coordinates voluntary movement, posture and balance
Receives sensory input from muscles, joints eyes and ears
May have role in learning and language processing
How would you know if cerebellum is damaged?
Uncoordinated
Clumsy
Jerky movement
Where is the spinal cord located?
Within the vertebral canal, continuous with the brain stem.
From medulla to around L1 vertebra
What is the spinal cord surrounded by?
Meninges and cerebrospinal fluid (CSF)
How long is the spinal cord, in adult males?
45cm
What shape is the grey matter of the spinal cord?
H
Where is the CSF located in the spinal cord?
In the central canal
What is the spinal cord composed of?
Made up of sensory neurones, lower motor neurones and connector neurones connecting the sensory and motor
What does the acronym SAME stand for?
Sensory Afferent
Motor Efferent
What do the neurones in the spinal cord allow?
Spinal reflexes known to be caused by spinal reflex arc composed of motor, sensory and connector neurons
How are the cell bodies in the posterior column of grey matter in the spinal cord stimulated?
By sensory input of peripheries
How are the cell bodies of lower motor neurones in the anterior columns of grey matter in the spinal cord stimulated?
They are stimulated by upper motor neurones
How many columns/tracts of white matter are there in the spinal cord?
3
What are the positions of the three columns of white matter in the spinal cord?
Anterior
Posterior
Lateral
How is white matter formed?
Formed by sensory nerve fibres to brain and motor nerve fibres from brain and fibres of connective neurones
How many C spine vertebra are there?
7
How many thoracic vertebra are there?
12
How many lumbar vertebra are there?
5
How many sacral vertebrae are there?
5
How many coccyx vertebrae are there? (Fused)
4
What is a reflex?
An immediate involuntary action due to sensory stimulus like touching a hot surface
Describe the process of the reflex arc.
A stimulus like a pin causes pain.
Sensory receptors pick up stimulus on the skin.
Afferent nerve carries impulse along sensory neurone.
Impulse transmitted along connector neurone to the efferent nerve.
Impulses sent along motor neurone.
Impulse activates the effector, causing it to move away.
What are meninges?
The layers of the brain
What are the three layers of the brain?
Dura mater
Arachnoid mater
Pia mater
What is the dura mater split into?
The periosteal and meninges dura mater
What is the potential space between the arachnoid mater and the pia mater called?
The subarachnoid space
What is the potential space between the dura mater and the arachnoid mater called?
Subdural
What is contained in the subarachnoid space?
CSF
What is the purpose of the periosteal dura mater?
Serves as the skull inner periosteum called the endocardium which provides blood and nutrients to the bone
What is the purpose of the meningeal dura mater?
It provides a protective covering of the brain
What is spinal dura mater? (2)
A loose sheath around the spinal cord.
It is an extension of the cerebral dura mater separates from the periosteum of vertebrae by epidural space which contains blood vessels
Where is the spinal dura mater located?
From the foramen magnum (S2 vertebra) which them dudes with periosteum of coccyx
What is the foramen magnum?
The hole in the base of the skull through which the spinal cord passes
What is the condition that causes the brain tissue to settle into the spinal canal (foramen magnum)?
Chiari malformation
Where is the arachnoid mater located?
Between the dura and pia mater
Where does the arachnoid mater pass over?
Over convolutions of the brain and continues down the spinal cord until it fuses with the dura mater at the 2nd sacral vertebra
What are key characteristics of the pia mater?
It is delicate, connective tissue
Contains tiny blood vessels
Where is the pia mater located?
It is attached to the brain (third layer closest to brain) and continues to surround the spinal cord
What is the main functions of the cerebrospinal fluid? (5)
Support and protect
Maintain uniform pressure
Cushion/shock absorber between brain and skull
Moistens brain and spinal cord
Exchange of waste and nutrients between CSF and nerve cells
What does s container in the CSF?
Water Minerals salts Glucose Plasma proteins Creatinine Urea Few leukocytes
How is the CSF circulated? (4)
CSF produced by the CHOROID PLEXUS of each ventricle
CSF flows through the ventricles and into the subarachnoid space via the median and lateral apertures. Some CSF flows through the central canal of the spinal cord
CSF flows through the subarachnoid space
CSF absorber into the rural venous sinuses via the arachnoid villi
What is the name of the four foramen in the brain?
Foramen of Monro or Interventricular foramine
(1st foramen)
Foramen of Magendie
(Median aperture)
Foramen of Luschka x2
(Lateral aperture)
What is the subarachnoid space?
The space between the arachnoid membrane and pia mater that is filled with CSF and contain large blood vessels that supply the brain and spinal cord
What is the foramen magnum?
The hole in the base of the skull through which the spinal cord passes
