peripheral nervous system Flashcards
- What is a dermatome?
- What is a myotome?
Area of skin that is supplied by a single spinal nerve
Group of muscles innervated by a single spinal nerve
- How many pairs of cranial nerves are there?
- How many pairs of spinal nerves are there?
12
31
- What can visceral efferent nerves be divided into?
- What do these types of nerves innervate?
Parasympathetic and sympathetic
Sympathetic efferent nerves innervate the viscera (organs) **and periphery** (vasculature and sweat glands) Parasympathetic efferent nerves innervate the viscera (organs) only
- What is a ganglion?
- What is a nucleus?
- What is a plexus?
Collection of cell bodies outside the CNS
Collection of cell bodies inside the CNS Network of interconnecting nerve
- Where do all afferent fibres have their cell bodies?
- Where do visceral efferent nerves synapse?
Spinal ganglia
peripheral ganglia
- How are the peripheral nerves arranged?
Fasciculi (singular fasciculus) - bundles of neurons
3 layers of connective tissue: 1. Epineurium - external vascular layer 2. Perineurium - covers individual fascicles 3. Endoneurium - individual axons covered
- How can you classify conduction velocity and axonal diameter of peripheral nerves?
Based on conduction velocity:
Use letters A,B and C - A is the fastest Based on axonal diameter (sensory only): Use Roman numerals I-IV; with I being the largest diameter
- What 2 properties do the faster conducting peripheral nerves have?
Myelination
Larger diameter
- What type of sensory receptors respond to external stimuli and give examples of these stimuli?
Exteroreceptors
Pain, temperature, touch and pressure
- What types of sensory receptors respond to internal stimuli and give examples of these stimuli?
Proprioreceptors → Movement and joint position
Enteroreceptors → Movement through gut and blood pH
- List other types of sensory receptors classified by their mode of detection and what they detect
- Chemoreceptor- Detector molecules which bind to receptor e.g. in olfactory bulb
- Photoreceptor- Detect light in retina
- Thermoreceptors- Detect temperature in skin
- Mechanoreceptors- Mechanical opening of ion channels; e.g. touch receptors in skin
- Nociceptors- Detect tissue damage → then interpreted as by NS as pain
- Where are proprioreceptors found and what is detected at each of these locations?
- Muscle spindles- Small sensory organs in skeletal muscles that detect whether muscle has been stretched
Detect changes in muscle length- Golgi tendon organs- Detect changes in tension in tendons
- Joint receptors- Found in joint capsules and detects start and end of movement (give you a sense of where your body is in space)
- What is a neuromuscular junction?
- What is a motor unit?
Specialised synapse between a motor neurone and a muscle fibre
Single motor neurone together with all the muscle fibres that it innervates It is the smallest functional unit with which to produce a force
- How many motor neurones and skeletal muscles do humans have approximately?
- What does the stimulation of one motor unit cause?
420,000 motor neurones
250 million skeletal muscle fibres On average each motor neurone supplies about 600 muscle fibres Contraction of all the muscle fibres in that unit
- What is a reflex action?
Involuntary coordinated pattern of muscle contraction and relaxation elicited by peripheral stimuli
- Outline the process of the tendon reflex action
- Stretching stimulates sensory receptors (muscle spindle)
- Sensory neurone activated
- Sensory neurone activates motor neurone within the spinal cord (integrating centre)
- Motor neurone is activated
- Effector (quadricep muscle of thigh) contract
- Where is the sympathetic system said to have its outflow and what is this outflow known as?
Thoracolumbar region of spinal cord
So cells only emerge from T1 to L2 Thoracolumbar outflow
- Where is the parasympathetic system said to have its outflow and what this outflow also known as?
Pre-ganglionic neurones emerge from the brain stem and sacral portion of spinal cord (3, 7, 9 ,10) and S2-S4 parts
Craniosacral outflow
- What information does the Visceral sensory neurone relay to the to the ANS?
- Which cranial nerves do the visceral sensory neurones run to?
- what are the areas of its outflow
Pain, fullness, blood pressure
IX - Glossopharyngeal Nerve X - Vagus Nerve
T1-L2 , S2-S4, nerves IX and X
- What do the visceral motor neurones control?
- Can you see spinal sympathetic nerves emerging from either the cervical cord or the low lumbar cord?
Pupils, sweat glands, salivary glands, heart muscle, airways
no
- What is the grey matter in the middle of the thoracolumbar cord called and what does it contain?
- Why are the white ramus communicans white?
Lateral horn (anterolateral horn)
Cell bodies of the sympathetic outflow going off into structures such as the sympathetic ganglia or sympathetic chains The pre-ganglionic neurones are more myelinated
what is the difference between grey and white ramus communicans?
white ramus communicans carries preganglionic sympathetic fibers to the sympathetic chain
while the gray ramus contains postganglionic sympathetic fibers rejoining the spinal nerve
- Describe the pathway of a nerve impulse on the sympathetic outflow to the heart via cervical region
Thoracic Segment 1 can send out a pre-ganglionic sympathetic nerve which goes into the mixed spinal nerve
Takes a turn to synapse and goes into sympathetic nerve via white ramus It then ascends up to sympathetic ganglia in the cervical region Then synapses in sympathetic chain and sends a post-ganglionic nerve out
- What happens in the sympathetic outflow to the viscera as there are no synapses in the sympathetic trunk?
- What are the pre-aortic ganglia?
Nerve impulses travel straight from sympathetic pre-ganglionic neurones to pre-aortic ganglia via splanchnic nerves
Cell bodies of the post-ganglionic neurones towards viscera are found here which then send their fibres out to the organs themselves They sit around the aorta
- Which cranial nerves are involved in the parasympathetic outflow to the viscera?
III - Oculomotor
VII - Facial IX - Glossopharyngeal X - Vagus
- What are the names of the organs that these cranial nerves parasympathetically affect and where they synapse to these organs?
III - Ciliary ganglion → Lacrimal gland
VII - Pterygopalatine ganglion → Pupillary constriction VII - Submandibular ganglion → Salivary gland IX - Otic ganglion→ Parotid gland
- Which cranial nerve supplies the heart and some gut structures with parasympathetic structures?
- What functions are carried out by the sacral pre-ganglionic nerves that go to the pelvic viscera?
X - Vagus
Erection Activation of pelvic viscera, e.g - of bladder and rectum
- What part of the brain lies in the anterior cranial fossa?
- What part of the brain lies in the middle cranial fossa?
- What part of the brain lies in the posterior cranial fossa?
- What lies directly above the body of the sphenoid bone?
Frontal lobe of cerebral hemisphere
Temporal lobe of cerebral hemisphere cerebellum hypothalamus
- Which part of the ventricular system relates to the cerebral hemisphere?
- Which part of the ventricular system relates to the diencephalon?
- Which part of the ventricular system relates to the midbrain?
- Which part of the ventricular system relates to the pons and medulla?
Lateral ventricle
Third Ventricle
Cerebral aqueduct
Fourth Ventricle
- What blood vessel supplies the primary motor cortex for feet?
- What cortical area(s) does the posterior cerebral artery supply?
Anterior cerebral artery
primary visual cortex
- What cortical area(s) does the middle cerebral artery supply?
Primary motor cortex for face and arm
Primary somatosensory cortex for arm Primary auditory cortex Broca's area Wernicke's area
- What are the 3 cerebellar peduncles connecting the brainstem to the cerebellum also known as?
- Which cranial nerve nuclei are found in the brainstem?
White Fibre Tracts
III - XII (excluding XI)
- Which section of the brainstem is found anterior to the Tectum?
- What are the 2 sections at the anterior of the brainstem called?
Tegmentum
Bases
- Which of the anterior and posterior surfaces of the medulla has the pyramids and which has the dorsal columns?
what do the pyramids contain?
Anterior - Pyramids
Posterior - Dorsal columns
motor fibres of corticospinal and corticobulbar tract
- which 2 arterial systems supply the CNS?
- what is each system derived from and what does it supply?
Anterior and Posterior
Anterior from Internal carotid system, cerebral hemispheres
Posterior from vertebrobasilar, brainstem
- What are the functions of the General Somatic Afferent Nerves?
- What are the functions of the General Somatic Efferent Nerves?
Fibres carrying general sensation from skin, muscles, joints of head and neck
Fibres innervate skeletal muscles
- What are the functions of the General Visceral Afferent Nerves?
- What are the functions of the General Visceral Efferent Nerves?
Fibres carry sensation from viscera of head, neck, thorax and abdomen
Fibres are the preganglionic parasympathetic neurons to cranial, thoracic and abdominal viscera
- What are the functions of the Special Somatic Afferent components?
- What are the functions of the Special Visceral Afferent components?
- What are the functions of the Special Visceral Efferent components?
Fibres carry special senses of hearing and balance
Fibres carry taste sensation Innervate skeletal muscles of the jaw, face, larynx and pharynx
Key features of the Midbrain?
aqueduct
nerves 3 and 4
cerebral peduncle most prominent
superior (for orientating vision) and inferior (for orientating hearing) cocculi
Key features of Pons?
4th ventricle
Pontine nuclei
transverse fibres
nerves 5, 6, 7, 8 emerge
What is the posterior surface of the medulla divided into?
Key features of open medulla ?
open and closed
4th ventricle
inferior olivary nucleus
nerves 9, 10, 12 emerge
Key features of the closed Medulla?
Dorsal columns
extension of Central Canal, which widens to form 4th ventricle in open medulla
Decussation of pyramids
cranial nerves 9, 10, 12 emerge
