Module 6 Flashcards
What are two types of nerves contained in the peripheral nervous system?
spinal and cranial
What division of the PNS transmits sensory information from the periphery to the CNS?
Sensory (Afferent)
What division of the PNS transmits motor commands from the CNS to the periphery?
Motor (Efferent)
What division of the PNS is in charge of voluntary motor control of skeletal muscles?
Somatic
What division of the PNS is in charge of fight or flight response?
Sympathetic
What division of the PNS is in charge of involuntary motor control of the smooth and cardiac muscle?
Autonomic
What division of the PNS is in charge of the rest and digest response?
Parasympathetic
How many pairs of cranial nerves are there?
12
Where do the cranial nerves emerge from?
Brain and brain stem
What are the types of information the cranial nerves carry?
Only sensory
Only motor
Both sensory and motor
What is the name & function of CN I?
Olfactory nerve
Sensory only
Sensory: Smell
What is the name & function of CN II?
Optic nerve
Sensory only
Sensory: Vision
What is the name & function of CN III?
Oculomotor nerve
Motor only
Motor: Movement of the eye
What is the name and function of CN IV?
Trochlear nerve
Motor only
Motor: Movement of the eye
What is the name and function of CN V?
Trigeminal nerve
Sensory and motor
Sensory: Forehead, eye, upper jaw, lower jaw
Motor: Muscles of mastication
What is the name and function of CN VI?
Abducens nerve
Motor only
Motor: Movement of eye
What muscle does the trigeminal nerve innervate?
Masseter
What is the name and function of CN VII?
Facial nerve
Motor and sensory
Sensory: Taste (anterior 2/3 of tongue)
Motor: Parasympathetic innervation of salivary glands and tears, facial expression
What is the name and function of CN VIII?
Vestibulocochlear nerve
Sensory only
Sensory: Hearing & Balance/equilibrium
What is the name and function of CN IX?
Glossopharyngeal nerve
Both motor and sensory
Sensory: Sensory innervation of pharynx, taste from posterior 1/3 of tongue
Motor: Pharynx muscle, parasympathetic innervation of salivary glands
What is the name and function of CN X?
Vagus nerve
Both motor and sensory
Sensory: Sensory innervation of larynx
Motor: Pharynx and larynx muscle, parasympathetic innervation of the thoracic and abdominal organs
What is the name and function of CN XI?
Accessory nerve
Motor only
Motor: Trapezius and sternocleidomastoid muscles
What is the name and function of CN XII?
Hypoglossal
Motor only
Motor: Muscles of the tongue
What are the two central nerves responsible for taste?
CN VII, CN IX
Facial (anterior 2/3)
Glossopharyngeal (posterior 1/3)
What’s the mnemonic for memorizing cranial nerve names?
Oh, Once One Takes The Anatomy Final Very Good Vacations Are Heavenly
What’s the mnemonic for memorizing the cranial nerve functions?
Some Say Money Matters, But My Brother Says Big Brains Matter More
Where do spinal nerves emerge from?
The spinal cord
How many pairs of spinal nerves are there?
31 pairs
A spinal nerve is formed by the union of the… roots of the spinal cord
Posterior (sensory), anterior (motor)
Spinal nerves can be identified based on a ________ and ________, similar to how vertebrae are classified
letter, number
What does the letter refer to (spinal nerve)?
Region of spinal cord
What does the number refer to (spinal nerve)?
Level of the spinal cord
In which region do spinal nerves emerge superior to their corresponding vertebrae?
Cervical region
Which cervical nerve is an exception that doesn’t emerge superior to its corresponding vertebrae? Where does it emerge instead?
C8 (because there is no C7 vertebra)
Instead emerges between C7 and T1
Below the neck, all spinal cords emerge… to its corresponding vertebra
inferior
Once the spinal nerves exit the vertebral column, fibres from the … come together and then redistribute into new networks of nerves (…) that mostly innervate …
anterior roots (motor), plexus, muscles of the limb
Each plexus contains … (a collection of …) from a combination of spinal nerves. This has functional importance because in the case of …, the contribution of multiple spinal nerves into the nerve plexus ensures innervation to the muscle
fibres, axons, injury
The main spinal nerve plexus in the body correspond to the … of the spinal cord. The _______ and _______ plexus correspond to the ___________ enlargement, while the _________ and _________ plexus correspond to the ______________ enlargement.
enlargements, cervical, branchial, cervical, lumbar, sacral, lubosacral
What is the autonomic nervous system also known as?
Visceral motor system
What is the autonomic nervous system responsible for? (3)
Transmitting involuntary signals from the CNS to smooth muscle, cardiac muscle, and glands
The ANS is a _______ neuron pathway… what does that mean?
two
Between the CNS and any target organ, there are two neurons
What are the components of the two neuron chain? (3)
1) Preganglionic neuron
2) Autonomic ganglion
3) Postganglionic neuron
Where is the cell body of the preganglioinic neuron located? Where does the axon enter?
Has its cell body within the CNS. The axon enters into the PNS and travels to the autonomic ganglion.
What is the autonomic ganglion?
Where the preganglionic and postganglionic neurons meet
Where is the autonomic ganglion located?
In the PNS
Where is the postganglionic neuron located?
Entirely in the PNS
Which neuron’s cell body is the autonomic gaglion?
The postganglionic neuron
Where does the axon of the postganglionic neuron go?
Travels to reach the target organ
What is the origin of the sympathetic nervous system?
Spinal cord segment T1-L2 (thoracolumbar division)
What is the origin of the parasympathetic nervous system?
Brainstem and spinal cord segment S2-S4 (also called craniosacral division)
What is the response of the sympathetic nervous system?
Fight or flight
What is the response produced by the parasympathetic nervous system?
Rest and digest
What is the effect produced by sympathetic nervous system (is it widely distributed or more limited)?
Widely distributed to many parts of the body
What is the effect produced by the parasympathetic nervous system (is it widely distributed or more limited)?
More limited distribution to target organs with localized effect
True or false: The sympathetic and parasympathetic systems also differ in how their associated nerves travel from the CNS to the target organs
True
The nerves of the sympathetic system exit from the spinal cord to supply innervation to the body. Can you describe the four steps of the sympathetic pathway?
1) Sympathetic preganglionic axons leave the lateral horn of the spinal cord, along with somatic motor axons, to form the anterior root
2) 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 superiorly and inferiorly.
3) Preganglionic neurons synapse with postganglionic neurons in the ganglia
4) Postganglionic axons leave the sympathetic trunk to enter the spinal nerve and extend to the effector tissue/organ at approximately that vertebral level
Describe the three steps of the parasympathetic pathway (describe 3 vaguely).
1) Preganglionic neurons leave brainstem or spinal cord at level of sacrum
2) Preganglionic neurons meet postganglionic neurons in ganglia close to viscera
3) Postganglionic neurons travel to effector organs
In the PARASYMPATHETIC PATHWAY, which postganglionic neurons supply the head?
CN III, VI, IX
In the PARASYMPATHETIC PATHWAY, what supplies the thorax and descending colon?
CN X
Which spinal nerves supply the terminal gut and pelvic viscera (bladder and reproductive organs)?
S 2, 3, 4
Vision requires special visual receptors called… located at the… of the eye
photoreceptors, back
Name three accessory structures of the eye
Lacrimal gland
Eyelid
Extrinsic eye muscles
What does the lacrimal gland do?
- Produces tears; keeps cornea (outside surface of eyeball) moist and clean
- Tear drainage system is also very important, and part of lacrimal apparatus (anterior view)
What does the eyelid do (specifically upper eyelid)? What muscles does it contain to help with its function?
Contains levator palpebrae superioris muscle and orbicularis oculi muscle which control the opening and closing of the eye, respectively
What do the extrinsic eye muscles do?
Allow you to move eyes to increase range of motion
The eyelid contains glands that produce lubricating secretions. If plugged, what can this lead to the development of?
A painful swelling, also known as a stye
What are the 6 extraocular eye muscles?
Superior oblique
Medial rectus
Inferior rectus
Superior rectus
Lateral rectus
Inferior oblique
The superior oblique muscle is located _________ and __________ to the superior rectus muscle
inferior, deep
The eye is separated into ________ fluid-filled cavities. These are delineated by the ________
two, lens
What is the anterior cavity composed of (2)? What are these filled with (material and name)?
Anterior and posterior chambers
Aqueous humour (watery type fluid)
What separates the anterior cavity of the eye from the posterior cavity?
Lens
What is the posterior cavity filled with? What material is this like?
Vitreous humour (gelatinous fluid)
The internal portion of the eye is composed of three layers also known as…
tunics
What are the three tunics in the internal portion of the eye? What do they each correspond to?
Deep Layer - Sensory (Retina)
Middle Layer - Vascular
Outer Layer - Fibrous
What does the sensory tunic consist of (4)?
Neural Layer
Optic Disc
Macula
CN II (optic nerve)
What is the outermost region of the neural layer made of? What are these cells sensitive to?
Photoreceptors; Light sensitive cells
What do photoreceptors send signals through?
- Send signals through smaller nerves.
- These signals then reach the axons of ganglion cells (located in the innermost layer of retina)
- The axons of the ganglion cells exit the back of the globe (eyeball) to the brain
- The axons form the optic nerve (cranial nerve II)
What are photoreceptors also known as?
Rods and cones
What occurs at the optic disc?
Smaller nerve cell axons converge
What’s the location you can see when you look into the eye?
Optic disc
Where is the macula? Where is it relative to the optic disc?
Central area of retina, lateral to optic disc
What is the central depression of the macula called?
Fovea
Where does fine detailed vision occur?
Fovea
What are the three parts of the vascular tunic?
Choroid, cilary body, iris
What is the vascular tract also known as?
Uveal tract
What’s the function of the choroid?
Contains blood vessels that supply eye with oxygen and nourishment
What does the cilary body produce? What does it contain? What does this control?
Aqueous humour
Cilary muscles (intrinsic eye muscles)
Cilary muscles control the shape of the lens
What muscles does the iris contain? Are these intrinsic or extrinsic? What do these control? What else does the iris contain? What do these do?
Sphincter and dilator muscles
Control narrowing and widening of pupil
Contain pigments
Give eye its colour
The fibrous tunic is the outermost layer of the eye and has two portions located internally and externally to the lens. These portions are continuous with one another. These are…
Sclera
Cornea
Is cornea located anterior or posterior to lens? Is it the internal or external layer of the fibrous tunic?
Anterior, external
Is sclera located anterior or posterior to lens? Is it the internal or external layer of fibrous tunic?
Posterior, internal
What part of the eye does the sclera form? What material is it made from? What does it act as a point of attachment for?
White portion
Layer of dense connective tissue
Acts as a point of attachment for extrinsic eye muscles
What colour is the cornea? What does it enable?
Transparent
Enables light transmission
Aqueous humour is produced by cilary processes in the … chamber
posterior
Flow of aqueous humour…
1) Flows through … into …
2) Aqueous humour exits at the … (…, …, …)
3) It passes through the … … into … canal
4) The aqueous humour enters … circulation
1) pupil, anterior chamber
2) anterior chamber angle, (junction of iris, cilary body, and cornea)
3) tribecular meshwork, Schlemm’s canal
4) systemic
Normally, the aqeuous humour is able to flow naturally from the eye. In ________, the flow is blocked, causing excess fluid to accumulate in the chambers of the eye. This puts an increased pressure on the structures in the eye, which can lead to damage of the neural tunic (or retina) and nerves in this layer).
Glaucoma
Damage to retina or neural tunic, inability to see, distortion of the optic nerve, and reduced vision are symptoms of what?
Glaucoma
What is the ear responsible for?
Hearing and equilibrium (or unconscious sense of balance)
What are the three parts the ear is divided into?
External ear
Middle ear
Inner ear
What is the structure of the ear you can touch?
External ear
Sound waves from the external environment travel through the … to reach the … causing it to vibrate.
external auditory canal, tympanic membrane
What marks the boundary between the external and middle ear?
Tympanic membrane
What are microscopic glands that are present in the external auditory canal? These glands also secrete ear wax.
Ceruminous glands
What impact is the perforated tympanic membrane likely to have on hearing?
Decreased or disrupted hearing
The middle ear is located within the … bone
temporal
Where does the middle ear span from?
Tympanic membrane to oval window
What are four features in the middle ear? TORE
Ossicles
Tympanic cavity
Round and oval windows
Eustachian tube
What are the ossicles? What do they do?
Small bones located in middle ear
Help transmit sound waves to receptors in inner ear
What is the tympanic cavity?
Chamber in the temporal bone
What are the round and oval windows?
Areas at which the middle ear connects to the inner ear
What is the Eustachian tube?
Connects the middle ear to the nasopharyx
What are the muscles attached to the ossicles called? What do they function to do?
Tensor tympani
Stapedius
Function to dampen very loud noises
What are the names of the ossicles from lateral to medial?
Malleus (hammer)
Incus (anvil)
Stapes (stirrup)
What ossicle is attached to and behind the tympanic membrane?
Malleus (hammer)
Where does the stapes sit?
oval window
Which is the smallest bone of the ossicles, and is about 1/3 the mass of the others?
Stapes
Where is the inner ear located?
Within temporal bone
What receptors does the inner ear house?
Receptors responsible for hearing and equilibrium
What are the two parts of the inner ear? What is each responsible for?
Vestibular apparatus (balance)
Cochlea (hearing)
What part of the inner ear looks like a seashell?
Cochlea
How many parts is the vestibular apparatus made of?
3
Both the cochlea and vestibular apparatus are structured as two channels in the bone called…
labyrinths
What are they, which is located in which?
Membranous is located within bony labyrinth
Both labyrinths are filled with fluids that allow us to hear or become aware of and monitor the position of our head. What is the membranous labyrinth filled with? What is the bony labyrinth filled with?
Membranous: Endolymph
Bony: Perilymph
What are the three structures of the vestibular apparatus? What are they each responsible for?
Semicircular Canals - rotational movement of head
Utricle and Saccule - positional movement of head
The cochlea is composed of three…
ducts
What are the three ducts in the cochlea?
Tympanic
Vestibular
Cochlear
What is located in the cochlear duct?
Organ of Corti
What is the Organ of Corti made of, what do these rest on?
Specialized cochlear hair cells that rest on the basilar membrane
What happens to the hair cells when the basilar membrane is moved by sound waves?
They fire an impulse, which is sent to the brain via CN VIII (vestibulocochlear) for interpretation
