Nervous System Flashcards
(21 cards)
What parts can the nervous system be divided into based on gross anatomy?
- Central nervous system - brain & spinal cord
- Peripheral nervous systen - 12 pairs of cranial nerves (arise directly from the brain), 31 pairs of spinal nerves (which arise from the spinal cord)
What parts can the nervous system be divided into functionally?
- Somatic nervous system - control of voluntary activities. ‘Motor’- control of skeletal muscles, ‘sensations’ which reach consciousness
- Autonomic nervous system - control of involuntary activities. ‘Motor’ - to glands, blood vessels, heart etc., ‘sensory’ - blood pressure, CO2 in blood, how full is the duodenum etc.
Autonomic nervous system is further divided into the 2 opposing systems: sympathetic (fight/flight) and parasympathetic (rest/digest)
What 3 components is the brain divide into?
Cerebrum - cerebral hemispheres
Cerebellum
Brainstem - midbrain, pons, meddulla
What are the cerebral hemispheres divided into?
Surface - frontal, parietal, temporal and occipital lobes
Deeper - basal ganglia, thalamus, internal capsule etc.
what are sulci and gyri?
gyri - folds of cerebrum
sulci - valleys separating gyri
what is the difference between white and grey matter?
white - myelinated neurones, found on the inside, where information is transmitted from one place to another
grey - unmyelinated neurones, found on the surface, where processing takes place
what are the roles of the brain stem?
transmits signals from the brain to the body (motor) and from the body to the brain (sensory).
Predominantly white matter.
What is the role of the cerebellum?
uses sensory information from the body to refine the motor instruction which the brain sends to the muscles - this produces coordinated movement
where is the central sulcus found? what is its role?
running across the part of the brain that lies under the parietal bone is the central sulcus, in front of which is the corresponding sensory gyrus. Role is control of muscles of the opposite side of the body; the motor cortex
Where are the meninges found? brief function & names of layers
The meninges are 3 protective layers lying between the skull and the brain itself. They have 3 main functions:
to protect the brain
to provide a framework for the blood supply
to enclose the fluid filled subarachnoid space
Layers are (in order closest - furthest from skull):
1. the dura
2. the arachnoid
3. the pia
Describe the ‘spaces’ between the meningeal layers
- Outside the dura - the extradural/epidural space (does not exist in the absence of pathology)
- The subdural space - between the dura and the arachnoid, does not exist in the absence of pathology
- The subarachnoid space - between the arachnoid and the pia mater - exists in healthy individuals and is filled with cerebrospinal fluid (CSF)
what is the role of CSF? How is it produced?
clear fluid providing nutrients to the brain and maintaining the balance of extracellular fluid.
Protects the brain by providing a cushion against trauma & prevents the delicate nervous and vascular structures from becoming compressed against the internal surface of the skull. Produced by a tissue called choroid plexus found within the ventricles of the brain.
Describe the ventricular system of the brain
The brain can be divided into 4 interconnected ventricles:
The right and left lateral ventricles - lie within the cerebral hemispheres, one on either side.
The third ventricle - in the midbrain.
The fourth ventricle - lies between the pons and medulla and in from of the cerebellum.
Cerebrospinal fluid flows from the lateral ventricles –> 3rd ventricle –> cerebral aqueduct –> fourth ventricle –> subarachnoid space, where it is absorbed into the venous sinuses and venous system
Describe the blood supply to the brain
2 internal carotid arteries and 2 vertebral arteries supply the brain. At the base of the brain these arteries form a ring of blood vessels called the Circle of Willis.
The Circle of Willis has 6 major branches, 3 on each side, including the anterior, middle and posterior arteries, each of which supplies a particular part of the cerebral hemispheres.
A clot in which vessel will cause a stroke?
the middle cerebral artery supplies most of the motor and sensory cortex and a blood clot in this vessel will cause that part of the brain to infarct, causing a stroke.
Describe the cranial nerves.
Nerves that arise directly from the substance of the brain. 12 pairs - some sensory, some motor, some mixed and some with autonomic function.
What is the function of the following cranial nerves (motor&/sensory, autonomic?):
1 Olfactory
2 Optic
3 Oculomotor
1 sensory (smell) 2 sensory (sight) 3 motor, movement of the eye. Autonomic to pupil and lens.
What is the function of the following cranial nerves (motor&/sensory, autonomic?):
4 Trochlear
5 Trigeminal
6 Abducens
4 motor, movement of the eye
5 sensory from the face, nose and oral cavity.
motor - chewing muscles.
6 motor, lateral (outward) movement of the eye
What is the function of the following cranial nerves (motor&/sensory, autonomic?):
7 facial
8 vestibulocochlear
9 glossopharyngeal
7 motor of facial expression sensory - taste autonomic to salivary glands 8 sensory (balance and hearing) 9 sensory from the tongue and pharynx autonomic to salivary glands
What is the function of the following cranial nerves (motor&/sensory, autonomic?):
10 Vagus
11 Accessory
12 Hypoglossal
10 autonomic motor to thoracic and abdominal organs
autonomic sensory from thoracic and abdominal organs
11 motor to head, shoulders, pharynx, larynx and soft palate
12 motor to tongue
There are 12 cranial nerves which are usually examined together.
Briefly outline the examination of the cranial nerves:
1 olfactory - ask about/test sense of smell
2 optic - test coloured vision/visual acuity/visual fields. Ophthalmoscopy to visualise the optic disc.
3 oculomotor, 4 throchlear, 6 abducens - ask pt to look at and follow your finger, make an H movement
5 trigeminal - sensory: test all sensory modalities at the 3 main branches (ophthalmic, maxillary, mandibular)
motor: test the temporal and master muscles by asking pt to clench their teeth
7 facial nerve - ask pt to shut their eyes as tight as posssible, raise their eyebrows then smile and whistle. Also test sensation on anterior 2/3 tongue.
8 vestibulocochlear - whisper in ear and ask them to repeat. Ring&Weber tests.
9 glossopharyngeal nerve, 10 vagus - tickle back of pharynx and look for gag reflex.
11 accessory - ask pt to shrug shoulders against resistance(trapezius muscle) and turn head on each side against resistance (sternocleidomastoid)
12 hypoglossol - tongue out as far as poss, is it straight or deviated to one side?
