MODULE 6: NERVOUS SYSTEM Flashcards
what are the divisions of the peripheral nervous system?
motor (efferent)
sensory (afferent)
somatic
autonomic
sympathetic
parasympathetic
motor division
efferent - transmits motor commands from CNS to periphery
sensory
(afferent) - transmits sensory information from periphery to CNS
somatic
voluntary motor control of skeletal system
autonomic
involuntary motor control of smooth and cardiac muscle
sympathetic
fight or flight response
parasympathetic
rest and digest
olfactory nerve
1- sensory : smell
motor : none
optic nerve
- sensory : vision
motor : none
oculomotor
- sensory: none
motor: movement of the eye
trochlear nerve
- sensory : none
motor: movement of the eye
trigeminal nerve
- sensory: forehead, eye, upper jaw, lower jaw
motor: muscles of mastication
abducens nerve
- sensory: none
motor: movement of the eye
facial nerve
- sensory: taste for anterior 2/3 of tongue
motor: muscles or facial expression. parasympathetic innervation of tear and salivary glands
vestibulocochlear nerve
8: sensory: equilibrium and hearing
motor:none
glossopharyngeal nerve
9: sensory: innervation of the pharynx. taste for posterior 1/3 of tongue.
motor: pharynx muscles, salivary glands.
vagus nerve
- sensory: innervation of larynx. motor: pharynx and larynx muscles. parasympathetic innervation of thoracic and abdominal organs
accessory nerve
- sensory: none
motor: trapezius and sternocleidomastoid muscles.
hypoglossal nerve
- sensory: none
motor: muscles or the tongue
how is a spinal nerve formed
the union of the posterior(sensory) and anterior (motor) roots of the spinal cord
how many spinal nerves are there
31
a two neuron pathway. between the CNS and any target organs, there are two neurons.
Autonomic nervous system
this fibre/ neuron has its cell body within the CNS. it’s axon enters into the PNS and travels through the autonomic ganglion
preganglionic fibre
where the preganglionic and post ganglionic neurons meet and communicate. located in the PNS
autonomic ganglion
located entirely in the PNS, it’s cell body is in the autonomic ganglion, while it’s axon travels to the target organ
post ganglionic neuron
differences between sympathetic and parasympathetic
sympathetic : spinal cord segment T1- L2 ( thoracolumbar division)
fight or flight
widely distributed to many parts of the body
parasympathetic nervous system: brainstem and spinal cord segment S2- S4 ( also called craniosacral division) rest and digest.
more limited distribution to target organs, with localized effect
sympathetic pathways
1: Lateral horn of spinal cord - sympathetic preganglionic axons leave the lateral horn of the spinal cord, along with somatic motor axons, to form the anterior root.
2: sympathetic trunk - preganglionic axons pass through the spinal nerve to the sympathetic trunk, a structure lateral to the spinal cord on either side. the sympathetic trunk provides a pathway for the sympathetic fibres to travel through the body. both superior ly and inferiorly.
3: preganglionic neurons synapse and postganglionic neurons synapse with post ganglionic neurons in the ganglia
4: post ganglionic axons leave the sympathetic trunk to enter the spinal nerve and extend to the effector tissue/ organ at approximately that vertebral level
parasympathetic pathways
1: preganglionic neurons leave the brain or spinal cord at the level of the sacrum
2: preganglionic neurons meet postganglionic neurons in ganglia close to viscera
3: postganglionic neurons travel to effector organs:
postganglionic neurons from CN 3, 7 and 9 supply the head
CN X supplies the thorax to the descending colon
S2,3,4 supply the terminal gut and pelvic viscera ( bladder and reproductive organs)
this gland produces tears, which keep the cornea, or outside surface of the eyeball, moist and clean
Lacrimal gland
contains levator palpebrae superioris muscle and orbicularis oculi, which controls the opening and closing of the eyelid,
eyelid
six extrinsic eye muscles that allow you to move your eyes to increase range of motion.
extrinsic eye muscles
eye muscles
medial rectus
inferior rectus
superior oblique
superior rectus
lateral rectus
inferior oblique
eye cavities
posterior chamber
anterior chamber
anterior cavity
lens
posterior cavity
composed of the anterior and posterior chambers, both filled with aqueous humour
anterior cavity
separates the anterior cavity of the eye from the posterior cavity
lens
filled with vitreous humour ( gelatinous fluid)
posterior cavity
layers of the eye
outer layers - fibrous
middle layer - vascular
deep layer - sensory (retina)
internal aspect of the firbous tunic, located posterior to the lens. forms the white portion of the eye. it is layer of dense connective tissue that acts as a point of attachment for the extrinsic eye muscles
sclera
external aspect of fibrous tunic, located anterior to the lense. transparent enabling light transmission
cornea
external aspect of fibrous tunic, located anterior to the lense. transparent enabling light transmission
cornea
contains blood vessels that supply the eye with oxygen and nourishment
choroid
produces aqueous humour and contains the ciliary muscles ( intrinsic eye muscles) which controls shape of the lens
ciliary body
produces aqueous humour and contains the ciliary muscles ( intrinsic eye muscles) which controls shape of the lens
ciliary body
contains the sphincter and dilator muscles (intrinsic eye muscles) which control the narrowing and widening of the pupil. contain pigments, which gives the eye its colour
iris
consists of the neural layer, optic disc, macula, and CN ii (optic nerve). this layer is also known as the retina
sensory tunic (Retina)
made up of photoreceptors. (rods and cones), which are light sensitive cells. these receptor send signals through smaller nerves to the axons of the ganglion cells ( inner most layer of the retina) exit the posterior aspect of the globe to the brain to form CN ii
neural layer
made up of photoreceptors. (rods and cones), which are light sensitive cells. these receptor send signals through smaller nerves to the axons of the ganglion cells ( inner most layer of the retina) exit the posterior aspect of the globe to the brain to form CN ii
neural layer
area where smaller nerve cell axons converge.
optic disc
central area of retina, lateral to optic disc.
macula
central depression of macula where fine detailed vision occurs
fovea
disease where aqueous humour is not able to flow freely. this causes excess fluid to accumulate in the chambers of the eye, increases pressure on structures in the eyes, leads to damage of the neural tunic or retina and nerves in this layer
glaucoma
