Exam 3- Spinal Cord and Special Senses Flashcards
What types of tracts does the spinal cord contain?
- Ascending sensory (afferent) fiber tracts
2. Descending motor (efferent) fiber tracts
What do the sensory and motor tracts of the spinal cord course between?
The brain and sensory receptors of the PNS
The spinal cord also serves as an area of synaptic transmission between motor and sensory neurons via ______
interneurons
In the spinal cord, gray matter is an area of what?
Cell bodies within the CNS
In the spinal cord, white matter is an area of what?
Axons or fibers within the CNS
Where do dorsal roots arise from? (as a whole)
The dorsal surface of the spinal cord
What type of neurons do dorsal roots contain?
Sensory neurons only
Where do the dorsal rootlets enter the spinal cord?
dorsal horn of the spinal cord gray matter
Name the sections of the dorsal area of the spinal cord in order.
- Dorsal rootlets
- Dorsal root
- Dorsal root ganglion
- Spinal Nerve (mixed sensory/motor)
- Dorsal ramus (rami is plural)
What is a ganglion?
Area of cell bodies outside the CNS
What does the dorsal root ganglion contain?
Cell bodies of sensory neurons
Name the sections of the ventral area of the spinal cord in order.
- Ventral rootlets
- Ventral root
- Spinal Nerve (mixed sensory/motor)
- Ventral ramus (rami is plural)
What does gray matter of the spinal cord form?
ventral, dorsal and lateral horns
Where does the ventral root of the spinal cord arise from? (as a whole)
The ventral surface of the spinal cord
What type of neurons do the ventral roots contain?
Contains the AXONS of motor neurons only
Where do the ventral rootlets enter the spinal cord?
Ventral horn of the spinal cord gray matter
What combines to make the spinal nerve?
Ventral and Dorsal Roots
What does the spinal nerve transverse?
intervertebral foramen on either side of the vertebral column
What type of nerve fibers does the spinal nerve contain?
Motor and sensory nerve fibers
Which is larger, the ventral or doral ramus?
Ventral
What does the ventral ramus supply?
- Anterior trunk of the body (thorax and abdomen)
- Upper and Lower limbs
- Pelvic regions
What does the dorsal ramus supply?
All the structures on the back of the body: including muscular distribution to the deep back muscles and cutaneous distribution to the skin of the back
What do Interneurons or internuncial neurons do?
Form synapses (connections) between sensory and motor neurons
Where do motor or efferent neurons have their cell bodies?
Within the gray matter of the spinal cord
Where do sensory nerves travel through when they are coming into the CNS?
dorsal and ventral rami
Rami tell us what?
From what part of a body an impulse is coming from or going to
Roots tell us what?
type of impulse (sensory or motor)
Describe the tract of a sensory (afferent nerve)
- Travel through dorsal and ventral rami
- Mixed spinal nerve
- Dorsal root ganglion
- Travel within the Dorsal root towards the spinal cord
- Ascend within the white matter of the spinal cord to the brain
Describe the tract of a Motor (efferent nerve)
- Descend from the brain through the white matter of the spinal cord
- Motor nerve fibers pass through the ventral roots
- Motor nerve fibers course into the mixed spinal nerve which traverses the intervertebral foramen
- Motor nerve fibers course through the ventral and dorsal rami toward the effector organs they innervate.
How many cervical spinal nerves are there? How many cervical vertebrae are there?
- 8
2. 7
In the spinal cord which matter (gray or white) is external?
White
Where does the first cervical spinal nerve emerge?
Above the ATLAS (C1)
Where does each spinal nerve after and including C1 emerge in relation to the vertebrae?
Numerically to the vertebrae beneath it (so above the vertebrae) UNTIL C8
Where does each spinal nerve after and including C8 emerge in relation to the vertebrae?
Numerically to the vertebrae above it (so below the vertebrae)
Where does the 8th cervical spinal nerve emerge?
beneath vertebrae C7 (vertebra prominens)
Where does the first thoracic spinal nerve emerge?
beneath T1
How many pairs of thoracic spinal nerves are there? Where does each thoracic spinal nerve correspond numerically in relation to the vertebrae?
- 12 (T1-T12)
2. Each thoracic spinal nerve corresponds numerically to the vertebrae directly above it
How many pairs of lumbar spinal nerves are there? Where does each thoracic spinal nerve correspond numerically in relation to the vertebrae?
- 5 (L1-L5)
2. Each lumbar spinal nerve corresponds numerically to the vertebrae directly above it
How many pairs of sacral spinal nerves are there? Where do they emerge?
- 5 (S1-S5)
2. Emerge through the pelvic and dorsal sacral foramina and sacral hiatus of the sacrum.
How many pairs of Coccygeal Spinal nerves are there? Where do they emerge?
- 1
2. Emerge through the sacral hiatus above the coccyx
Where do the roots which comprise the Sacral and Coccygeal Spinal Nerves emerge from? Where do they continue to course through?
- The end of the spinal cord (the conus medullar is)
2. They continue to course through the vertebral canal as the cauda equina
What part of the vertebral canal does the spinal cord occupy?
upper 2/3rds of the vertebral canal
Where does the spinal cord end? (vertebrae)
level of the second lumbar vertebrae (L2)
What is the lower cone shaped end of the spinal cord referred to?
Conus Medullaris
What is the portion of the vertebral canal inferior to L2 referred to as?
Cauda Equina (horses tail)
What does the Cauda Equina consist of?
ventral and dorsal roots of the lower spinal nerves
What are the 3 meninges of the spinal cord?
- Dura Matter
- Arachnoid matter
- Pia Matter
What is the dura matter composed of?
dense fibrous connective tissue
Where does the dura matter, arachnoid matter, and filum terminale end in the vertebral canal?
coccyx
What is in-between the arachnoid and pia matter? What does it contain?
- Sub arachnoid space
2. CSF
What does the pia matter adhere to?
adheres to the surface of the brain and spinal cord
What is the pia matter referred to inferior from the conus medularis
filum terminale
What is the function of the filum terminale?
anchors the spinal cord in place and prevents its distortion with movements of the body
What are the 3 layers of the eye from outermost to innermost?
- Sclera
- Choroid
- Retina
What is the diameter of the eyeball?
2.5 centimeters
What is the cornea aka?
“window of the eye”
What is the composition of the sclera?
white/fibrous
What is the composition of the choroid?
dark brown/very vascular
What is the function of the choroid?
serves to absorb stray light rays
Where does the choroid thicken? What does it form?
- Toward the front of eye
2. Ring shaped ciliary body
What does the ciliary body contain?
Ciliary Muscles
What do the ciliary muscles control?
control the shape of the lens for close and distant visual acuity
What are ciliary muscles attached to?
suspensory ligaments
What is lens accommodation accomplished by?
Lens accommodation is accomplished by contraction of the ciliary muscles
What do the suspensory ligaments attach to?
The suspensory ligaments attach to the periphery of the lens
ciliary muscles are attached to _______ which are in turn attached to the periphery of the lens
suspensory ligaments
What happens when ciliary muscles contract? What does this allow us to do?
- Contraction of the ciliary muscles will result in flattening of the lens
- Allows us to focus on distant objects
Where does the Iris arise from?
choroid
What is composition of the iris?
muscular pigmented diaphragm
What is the function of the iris?
regulates the size of the pupil
Where is the pupil located? What is its function?
- Hole in the center of the iris
2. Through which light passes into the eyeball
What divides the eye into 2 separate chambers? What are these 2 chambers called?
- The lens
2. Anterior and posterior cavities or chambers
How does the eye maintain its globular shape?
through pressure that is maintained by the two fluids found within the 2 chambers of the eye (Vitreous Humor and Aqueous Humor)
What fluid fills the posterior chamber/cavity of the eye?
Vitreous Humor
What fluid fills the anterior chamber/cavity of the eye?
Aqueous Humor
What is the composition of the Vitreous Humor? How is the volume of this fluid held at?
- clear, gelatinous material
2. Constant volume
The posterior cavity or chamber of the eye is ______ to the lens
posterior
The anterior cavity or chamber of the eye is posterior to the ______ and anterior to the ______.
- Cornea
2. Lens
What is the composition of the aqueous humor? What secretes the aqueous humor?
- clear, watery fluid
2. ciliary bodies
What cells does the retina contain?
rod and cone cells
What type of cells are cones and rods?
photoreceptor cells
Which are more sensitive to light, rods or cones?
rods
Rod cells are used for seeing what?
allow for vision at low light levels and color
cones are used for?
visual acuity
What layer of the eye is the Fovea Centralis in?
Retina
What area of the retina only contains cone cells?
Fovea Centralis
What is the area of the retina with the highest visual acuity?
Fovea Centralis
Where are the no cone or rods cells? What is this area referred to?
- Optic Disc
2. Blind spot
Where does the optic nerve transverse?
Optic disc
What structure does the sclera of the eye contain?
Cornea (window of the eye)
What structures does the retina of the eye contain?
- Rods (night vision)
- Cones (acuity)
- Fovea Centralis (yellow ovalish depression/cones only)
- Optic disc (blind spot)
What structures does the choroid of the eye contain?
- Ciliary bodies (control lens shape)
- Lens (divides eye into 2 chambers)
3 Iris (pigmented diaphragm/controls pupil size)
What are the 3 divisions of the ear?
- Outer
- Middle
- Inner
What 2 sensory functions is the ear responsible for?
- Equilibrium (balance)
2. Hearing
Where exactly is the outer ear?
auricle to tympanic membrane
Where exactly is the middle ear?
tympanic membrane to oval window
Where exactly is the inner ear?
oval window inward
What two structures are contained within the outer ear?
- Pinna (external flap made of cartilage and skin)
2. Auditory canal
What is the pinna made of?
external flap made of cartilage and skin
What is the tympanic membrane AKA?
eardrum
What are the three small bones found between the middle ear collectively called? What are the specific names of each?
- Ossicles
- Ossicle Names:
1. Malleus (hammer)
2. Incus (anvil)
3. Stapes (stirrup)
What does the malleus attach to?
the tympanic membrane (eardrum)
What does the stapes contact?
the oval window
What is the eustachian tube AKA?
Auditory tube
Where exactly is the eustachian tube located?
extends from the middle ear to the nasopharynx
What is the function of the eustachian tube?
Equalization of air pressure when we swallow/yawn
What structures are contained within the middle ear?
- 3 ossicles
- Malleus–>tympanic membrane
- Incus
- Stapes–>oval window
- Eustachian tube (auditory tube) (Equalization of pressure)
What are the 3 regions of the inner ear?
- Semicircular canals (equilibrium/balance)
- Vestibule (equilibrium/balance)
- Cochlea (hearing)
What are the semicircular canals and vestibule of the ear involved with?
equilibrium and help to maintain balance
What is the cochlea of the ear involved with?
hearing
What is the cochlea lined with?
small hairs called sterocilia
What shape is the cochlea?
snail shaped
What does the movement of the sterocilia do?
transmits sensations to our brain to interpret sound
