Spinal Cord, reflexes and receptors Flashcards
(86 cards)
1
Q
The spinal cord begins where and ends where?
A
Begins at medulla oblongata to the conus medullaris.
2
Q
Within spinal cord, what are the 2 enlargements?
A
Cervical and lumbar
3
Q
Cervical enlargement is from which the __________ plexus is formed. It innervates the ________ extremities of which vertebraes?
A
Brachial, upper, C5-T1
4
Q
Lumbar enlargement is from which the __________ plexus is formed. It innervates the ________ extremities of which vertebraes?
A
Lumbar, lower, T12, L1-L4
5
Q
Of the spinal cord you have the anterior median ______ and the posterior median _______.
A
Fissure (ant), sulcus (pos)
6
Q
Is the “butterfly” of the spinal cord white or grey matter?
A
Grey
7
Q
Surrounding the butterfly of the spinal cord is white or grey matter?
A
White
8
Q
Which type of matter contains the bundles of myelinated fibers (tracts)?
A
White matter
9
Q
What do the dorsal roots contain?
A
Sensory neurons
10
Q
What do the ventral roots contain?
A
Axons of motor neurons
11
Q
The dorsal roots and ventral roots come together to form what?
A
The spinal nerve
12
Q
The spinal nerve divides into the…
A
dorsal and ventral rami
13
Q
What does the dorsal rami supply?
A
The deep vertebral muscles and skin of the back
14
Q
What ventral rami supplies what?
A
All the ventral and lateral musculature.
15
Q
The denticulate ligaments extend what length?
A
The length of the spinal cord
16
Q
Learn the layers of meninges of the spinal cord*** (look up image
A
:)
17
Q
WHere does the spinal cord end?
A
L1/L2 (conus medullaris)
18
Q
Where do the meninges stop (which vertebrae)?
A
S2
19
Q
Definition of receptors.
A
Structures that are generally activated by changes in, or stimuli from either the internal or external environments of the body.
20
Q
Define sensation.
A
a state of awareness of external and or internal conditions of the body.
21
Q
Define a stimulus.
A
May be from receptors of light, heat, pressure, mechanical energy, chemical energy, etc
22
Q
Define perception.
A
Conscious registration of a sensory stimulus.
23
Q
Define adaptation.
A
A decrease in sensation during a prolonged stimulus.
24
Q
What are free nerve endings?
A
Uncapsulated or bare nerve endings
25
Free nerve endings act primarily as...
pain receptors (nociceptors)
26
Free nerve endings also act as...
touch receptors at hair follicles.
27
What is Merkel's disc?
A flat saucer-shaped nerve ending, classified as a free nerve ending.
28
Are free nerve endings capsulated or noncapsulated?
noncapsulated
29
What kind of receptors are merkel's discs?
slow-adapting receptors of light touch.
mechanoreceptors found in the fingertips, hands, lips and external genitalia.
30
What is meissner's corpuscle?
A mass of dendrites encapsulated in a connective tissue capsule.
31
Meissner's corpuscles are sensitive to what?
Light
32
Where are meissner's corpuscles found?
In the skin (esp. finger tips), mucous membrane of tongue, other sensitive regions of the body.
33
What are pacinian corpuscles?
A multilayered connective tissue capsule surrounding a dendrite.
34
Pacinian corpuscles are stimulated by what?
Heavy pressure
35
Where are pacinian corpuscles located?
In the deeper layers of the skin, mesenteries and loose connective tissue. Also in joints, tendons and muscles.
36
Where are end-bulbs of Krause located?
Found in subcutaneous tissue; tip of tongue, cornea of eye and external genitalia.
37
What triggers end-bulbs of Krause?
cold receptors
38
What are ruffini's corpuscles?
Elongated encapsulated receptors
39
Where are ruffini's corpuscles located?
Deep in dermis, ligaments and tendons
40
What do ruffini's corpuscles respond to?
heavy/deep touch, continuous touch and stretching of the skin. Contribute to the kinesthetic sense of and control of finger position and movement.
41
Where are muscle spindles found?
In skeletal muscle belly
42
Explain how muscle spindles are kept and what supplies them.
Kept in a capsule, and within the capsule are specialized skeletal muscle fibers called intrafusal fibers. It is supplied by the sensory neurons.
43
What happens when the muscle is stretched?
The intrafusal fibers are stretched, which sends afferent nerve impulses back to the spinal nerve. In response, there is a stimulus of the motor neurons to the same muscle to contract it.
44
Muscle spindles are (stimulation/inhibitory). GTO are (stimulation/inhibitory).
Stimulation, inhibitory
45
What are the GTO composed of?
Dendrites that have many branches at the musculotendinous junction.
46
How does the muscle relax?
By inhibiting the motor neurons that would act to contract the muscle through efferent impulse.
47
GTO detects what?
The tension in a muscle (tendon)
48
Give an example of a somatic reflex.
General contraction of skeletal muscle.
49
Give an example of autonomic reflex.
(visceral reflex) constriction of bladder, artery constriction/dilation, cardiac and glandular function.
50
What are primitive reflexes?
Patterns necessary for survival, developed through man's evolutionary process.
51
Do infants have many or little primitive reflexes?
many
52
What are the 3 motor development stages...
1. the primitive reflex stage where movements are eratic and fuzzy
2. in the second stage, movement becomes more rhythmical.
3. suddenly, all traces of the reflex motor behaviour disappears.
53
Can reflexes disappear and come back?
Yes
54
Early reflex patterns are primarily controlled by the...
spinal cord
55
Eventually early reflex patterns will be controlled by?
The CNS, until all movements are under cortical control.
56
Why do reflexes disappear?
To make room for movement patterns of higher organization.
57
Explain the sizes of the brain, cerebellum and brain stem from 3 months post-natally and a year post-natally.
Cerebellum increases, brain size triples and the brain stem recedes.
58
Most of the monosynaptic and polysynaptic reflexes appear after the ______ gestational week.
32nd
59
Tone definition.
the ability of the muscle to resist a force for a considerable length of time without change in length.
60
At birth, which have increased tonus: flexors or extensors?
Flexors.
61
What is the palmar grasp reflex? When is it present?
Newborn has strong grasp when object is placed in hand, present by the 32nd gestational week.
62
When does the reflex disappear? What is the reflex replaced by?
By the 3rd month postpartum, the reflex disappears and is replaced by voluntary grasping.
63
When will the fetus protrude its lips in preparation for sucking?
By the 14th - 16th week.
64
What is developed in the mouth by this time (14-16 weeks), in order for the fetus to swallow?
tongue and pharynx
65
What is the rooting (search) reflex?
When the cheek is lightly touched, the infant turns its head towards he stimulus and purses the lips, searching for the nipple to be fed.
Also, touching the upper lip will open the baby's mouth.
66
What is the babinski reflex?
when the baby is SUPINE, and the plantar aspect is tickled, the foot and the hallux will dorsiflex and (sometimes the toes will abduct).
67
How long does the babinski reflex last?
lasts through the first year of infancy.
68
What is different in adults when coming the babinski response to the response of adults?
Adults would normally flex. So if the child is doing abduction of toes still after a year, there might be signs of underdevelopment.
69
What is probably the most important reflex test on an infant?
Moro reflex
70
What is the moro reflex?
infant held in arms in supine position, head is let go a few cms abruptly, then the hips flex, the arms tense in an extended position and execute a wide embrace. Fingers bilaterally extend with the index finger and thumb forming a C
71
When does the moro reflex appear?
appears by the 36th week of gestation
72
When does the moro reflex disappear around?
the 3rd of 4th month.
73
What happens if the moro test lasts longer than 4 months?
suspect a neurological defect.
74
If its still present after 6 months, what does that mean?
Definite abnormality.
75
What is the tonic neck reflex?
Head is turned quickly to one side in a supine position. The arm and leg of that side will extend. The opposite limbs will flex.
76
When does the tonic neck reflex generally happen?
Can be present at birth, but peaks at 2-3 months after birth.
77
The fencing position will be present for _______ months.
4-6 months
78
What is the primitive walking (plantar) reflex?
When lightly propelled, the infant makes coordinated walking movements.
79
[CP] What is the positive supporting reflex?
When a newborn is supported vertically with the plantar aspects on the floor. the legs extend as if to partially support the infant. (This is the positive supporting reflex).
80
How long does the primitive walking reflex/positive supporting reflex last? When does it reappear?
Persist for 3-6 weeks, disappears, then reappears around 11-12 months.
81
What is the placing reflex? When is it present?
Place infants foot under table, they will raise it onto the table. Should be present in first 4 days after birth.
82
What is the swimming reflex? When is it present?
Swimming movements, present in babies up to 6 months. Then disappears for 18 months.
83
[CP] What is the laudau reflex? When is it present?
Support the baby's abdomen in a prone position, legs and arms dangling. Baby will lift head and extend spine and legs.
From the middle of the first year (6-8 months)
84
[CP] What is the parachute reflex? When does it first appear?
baby supported on abdomen in prone position. support is abruptly displaced, arms will extend and abduct. First appears around 6-9 months.
85
[CP] What is side turning reflex?
Where the baby is laid prone with head in a neutral central position. The baby should turn its head to one side to protect its airway.
86
[CP] What is the neck-righting reflex? When does it occur?
if you slowly turn the baby's head to one side, the body is sure to follow. This normally occurs from 3 months to 3 years. Then it disappears.
