The Nervous System Flashcards
1
Q
What are the 3 layers that encase peripheral from deep to superficial?
A
- Endoneurium
- Perineurium
- Epineurium
2
Q
Describe the connection between the epineurium and the surrounding connective tissue
A
It is continuous, but the attachment is loose so that nerve trunks are mobile
3
Q
Function of the spinal cord
A
- Participates in control of body movements
- Processing and transmission of sensory information from trunk/limbs
- Regulation of visceral functions
- Provides a conduit for two-way communication between brain and body
4
Q
How long is the spinal cord typically?
A
42-45cm long
5
Q
The spinal cord is continuous with the _____ superiorly and the _____ inferiorly
A
medulla
conus medullaris
6
Q
At when spinal level does the spinal cord end?
A
L1 or L2
7
Q
Posterior root of a spinal nerve contains _____ ganglion.
Anterior root of a spinal nerve contains _____ ganglion.
A
sensory
motor
8
Q
Between what 2 meningeal layers does CSF flow?
A
Between the arachnoid and the pia mater
9
Q
How do you test CN I?
A
Have your patient smell various odors with each nostril (vision occluded), such as coffee, lavender, vanilla
10
Q
How do you test CN II?
A
Test your patient’s visual acuity via the Snellen eye chart 20’ away
11
Q
How do you test CN III, IV, and VI?
A
Inspects the pupils for symmetry, their response to light, and their ability to track movement in the six fields of gaze (draw imaginary “H”)
12
Q
How do you test CN V?
A
Have your patient clench their teeth, while you palpate the temporal and masseter muscles.
You can also perform the pinprick test of the three branches of sensory nerves
13
Q
How do you test CN VII?
A
Inspect the patient’s face at rest, in conversation and in smiling
14
Q
How do you test CN VIII?
A
Assess your patient’s vestibulospinal reflex by testing the ability of the eyes to follow a moving object
The cochlear component can be tested by rubbing the fingers equidistant from the patient’s ears and assessing the response
15
Q
How do you test CN IX?
A
Test their gag reflex
16
Q
How do you test CN X?
A
Take note of any any hoarseness and nasal tones in the patient’s voice. Also ask your patient to open their mouth and say “Aahhh” while you watch the movements of the soft palate and pharynx
17
Q
How do you test CN XI?
A
Take note of any atrophy or asymmetry in the trapezius muscle.
Also, ask your patient to shrug shoulders
18
Q
How do you test CN XII?
A
Inspect the tongue as it lies on the floor of the mouth, looking for fasciculation.
Ask your patient to stick out their tongue and move it from side to side, taking note of any asymmetry
19
Q
There are 31 pairs of spinal nerves \_\_ cervical \_\_ thoracic \_\_ lumbar \_\_ sacral \_\_ coccygeal
A
8 12 5 5 1
20
Q
What are the 4 branches of a spinal nerve?
A
- Primary dorsal
- Primary ventral
- Communicating ramus
- Meningeal or recurrent meningeal
21
Q
The primary dorsal branch of a spinal nerve has a medial ____ branch and a lateral ____ branch
A
sensory
motor
22
Q
What does the primary ventral branch off a spinal nerve form?
A
the cervical, brachial, and lumbosacral plexuses
23
Q
The communicating rami connect what 2 structures?
A
spinal nerves and the sympathetic trunk
24
Q
What do meningeal (recurrent meningeal) branches do?
A
Carry sensory and vasomotor innervation to the meninges
25
What is a dermatome?
An area of nerve distribution
26
What is a myotome?
A muscle supplied by a single nerve root
27
What is a sclerotome?
bone/fascia supplied by a single nerve root
28
The cervical plexus is formed by what nerves?
The ventral primary divisions of C1-C4
29
What 3 muscles form the suboccipital triangle?
- Rectus Capitis Posterior Major
- Obliquus Capitis Superior
- Obliquus Capitis Inferior
30
What are the 3 things found in the suboccipital triangle?
- Vertebral Artery
- Suboccipital nerve
- Suboccipital Venous Plexus
31
What does the small occipital nerve supply?
Skin of the lateral occipital portion of the scalp, upper median part of the auricle, and the area over the mastoid process
32
What does the great auricular nerve supply?
sensation to the ear and the face
33
What does the cervical cutaneous nerve supply?
skin over the anterior portion of the neck
34
What do the supraclavicular branches supply?
skin over the clavicle and the upper deltoid and pectoral regions
35
What does the phrenic nerve supply?
Motor supply to the diaphragm
| Sensory supply to the pericardium, diaphragm, and part of the costal and mediastinal pleurae
36
The brachial plexus is formed by what nerves?
C5-T1
37
What is a common clinical presentation of a radial nerve lesion?
wrist drop
38
What is a common clinical presentation of a median nerve lesion?
Ape-hand deformity
39
What is a common clinical presentation of an ulnar nerve lesion?
Claw hand (bishop’s sign)
40
Intercostal nerves are from T_ - T_
T2 - T11
41
What do the intercostal nerves supply?
the thoracic and abdominal walls
42
The lumbar plexus is formed by what nerves?
(T12) L1-L4
S-I-I-G-L-O-F-L
43
The sacral plexus is formed by what nerves?
L4, L5 and S1-S4
S-I-P-P-S
44
What does the pudendal plexus supply?
the coccygeus, levator ani and sphincter ani externus muscles
45
What does the coccygeal plexus supply?
skin in the region of the coccyx
46
The autonomic nervous system is responsible for the innervation of what 3 things?
- Smooth muscle
- Cardiac muscle
- Glands of the body
47
What are the 2 divisions of the ANS?
Sympathetic and Parasympathetic
48
Neuromuscular control involves the integration of motor learning and control by way of what motor systems?
- Corticospinal tract
- Rubrospinal tract
- Vestibulospinal tract
- Reticulospinal tract
49
What is the corticospinal tract involved in?
skilled voluntary movement
50
What is the rubrospinal tract involved in?
Rapid, coordinated movement of the limb
51
What is the vestibulospinal tract involved in?
Integration of information from the vestibular system to control eye movement, head/neck movement, and postural reactions for balance
52
What is the reticulospinal tract involved in?
Movement planning, initiation of proper stability in posture and proximal limb to allow movement distally
53
What is open-loop neuromuscular control?
Actions that do not require sensory information to be performed (signing your name for example)
54
What is closed-loop neuromuscular control?
Actions that require sensory information for modification
55
What are the 2 types of closed-loop neuromuscular control and examples of each
- Reactionary: feedback (the thermostat in your home)
| - Anticipatory: feedforward (the anticipation that you may need a new car and purchase one before your car breaks down)
56
What does proprioceptive involve?
Integration of sensory input concerning static joint position, joint movement, velocity of movement, and the force of muscular contraction from the skin, muscles and joints
57
What are the 4 primary types of joint receptors?
- Pacinian corpuscles
- Ruffini endings
- Golgi tendon organ (GTO)
- Bare nerve endings
58
What do Pacinian corpuscles sense?
joint compression and increased hydrostatic pressure of the joint
59
What do Ruffini endings sense?
postural changes
60
What do Golgi tendon organs sense?
large amounts of tension
61
What do bare nerve endings sense?
mechanical deformation or tension
62
What is Kinesthesia?
the sense of movement of the body or one of the segments
63
Kinesthetic information travels up which motor pathway?
spinocerebellar tract
64
What are the 2 types of learning? What are the difference between the 2?
- Declarative learning involves just learning of the facts
| - Procedural learning is dependent on practice, association, adaptation, habituation and sensitization
65
What are the 3 types of motor tasks? Explain each
- Discrete: movement with a recognizable beginning and end
- Serial: series of discrete movements that are combined in a sequence
- Continuous: repetitive, uninterrupted movements that have no distinct beginning and ending
66
What are the 3 stages of motor learning? Explain each
- Cognitive: initial introduction; requires great concentration; variable performance filled with errors
- Associative: performing and refining skills; conscious decision making; concentration; less rushed
- Autonomous: efficient and nearly automatic performance
67
What are the 5 types of practices? Explain each
- Part: task is broken down into parts and each part is practiced
- Whole: entire task is performed from beginning to end; not practiced in separate components
- Blocked: performed repeatedly under the same conditions; predictable order
- Random: variation of the same task are performed in an unpredictable order
- Random blocked: variations of the same task are performed in random order, but each variation is performed more than once
68
Massed vs. Distributed Practice
- Massed involves participation in a long bout of practice with less time spent in rest breaks
- Distributed involves participation in a series of practices throughout the day
69
Second only to practice, ____ is considered the most important variable that influences learning.
feedback
70
Intrinsic vs. Extrinsic feedback
Intrinsic feedback is a natural part of the task that can take the form of a sensory cue inherent in the execution of the motor task.
Extrinsic feedback is supplemental feedback that is not normally an inherent part of the task in which the type, the timing, and the frequency can be controlled.
71
Knowledge of results vs. knowledge of performance
Knowledge of results includes immediate, post-task, extrinsic feedback about the outcome of the task
Knowledge of performance includes feedback given about the quality of the performance of the task
72
When is knowledge of results best utilized?
In instances when individuals are unable to generate feedback about the outcome of the task for themselves, or when the information may serve as a motivational tool
73
When is knowledge of performance best utilized?
This type of motor feedback better facilitates motor skill learning
74
Feedback about performance can be provided at various times throughout the task, what are these 2?
- Continuous
- Intermittent
- Immediate
- Delayed
- Summary
75
Open vs. Closed Skill Acquisition
Open skill acquisition involves temporal and spatial factors in an unpredictable environment
Closed skill acquisition involves spatial factors only in a predictable environment
76
Give an example of an open and closed skill in sports
Closed: shooting a FT into a static target
Open: throwing and TD pass to a moving target
77
What is balance?
A complex motor control task involving the detection and integration of sensory information to assess the position and motion of the body in space and execution of appropriate musculoskeletal responses to control body position with its stability limits and environment/task
78
What is posture?
the relationship of the various parts of the body with respect to one another, the environment, and to gravity
79
Balance results from an integration of what 3 components?
- Sensory processing via the nervous system
- Musculoskeletal contributions such as postural alignment, joint integrity, muscle performance, and mechanoreceptor sensation
- Contextual effects that interact with the nervous and musculoskeletal systems (i.e. closed/open environment, support surface, lighting, gravity, inertial forces, characteristics of the task)
80
When is an individual's balance greatest?
When the body's center of gravity is maintained over its base of support
81
What are the 3 types of balance control?
- Static Balance
- Dynamic Balance
- Autonomic Postural Reactions
82
Normal anteroposterior sway in adults is__ degrees
12
83
What are the 5 strategies designed to adjust the body's COG so that it is maintained with the BOS
- ankle strategy
- weight shifting strategy
- suspension strategy
- hip strategy
- stepping strategy
84
What do anticipatory postural adjustments respond to?
Internal perturbations such as voluntary movements of the body in advance of the actual perturbation
85
What initiates an anticipatory reaction?
the subject
86
What do compensatory postural adjustments respond to?
actual perturbations of balance that occur because of suboptimal efficacy of the anticipatory components
87
What initiates a compensatory reaction?
sensory feedback triggering signals
88
What is the most common determinant for a patient to seek intervention?
pain
89
Describe acute pain
Acute pain is the normal predicted physiological response to an adverse chemical, thermal or mechanical stimulus associated with surgery, trauma or acute illness
90
Acute pain is typically ____ in nature
chemical
91
What are the structures most sensitive to chemical irritation in order of sensitivity?
- Periosteum and joint capsule
- Subchondral bone, tendon and ligament
- Muscle and cortical bone
- Synovium and articular cartilage
92
Describe chronic pain
Chronic pain is typically more aggravating than worrying and lasts more than 6 months
93
5 characteristics of chronic pain
- Has been experienced before
- Mild to moderate in intensity
- Limited duration (although it can persist)
- Pain site does not cause alarm
- There are no alarming associated symptoms
94
Patients with chronic pain may be more prone to what?
depression and disrupted personal relationship
95
The symptoms of chronic pain typically behave in a mechanical fashion, what does this mean?
They are provoked by activity or repeated movements and reduced with rest or movement in the opposite direction
96
What is hyperalgesia?
an increased response to noxious stimulus
97
What is allodynia?
Pain in response to a previously innocuous stimulus
98
What is referred pain?
Pain at a site adjacent to or at a distance from the site of injury
99
What type of neuron transmits pain?
nociceptive neurons
100
Nociceptors are non-______ in nature
Non-adapting, meaning they will continue to fire for as long as the stimulus is present
101
What are the 3 ways in which nociceptive stimulation can occur?
Via mechanical deformation, excessive heat/cold or presence of chemical irritation
102
Transmission of pain to the CNS can occur via what 2 distinct pathways?
- Fast-conducting A delta fibers
| - Slow-conducting C fibers
103
Which pain pathways are myelinated and which are not?
Fast-conducting A delta fibers are myelinated and slow-conducting C fibers are not
104
Fast-conducting A delta fibers evoke what kind of pain?
rapid, sharp, lancinating pain
105
Slow-conducting C fibers evoke what kind of pain?
slow, dull, crawling pain
106
Pain signals from visceral and somatic tissues do one of what 3 things?
- Synapse with interneurons that synapse directly with motor nerves and produce reflex movements
- Synapse with autonomic fibers from the sympathetic and parasympathetic systems and produce autonomic reflexes
- Synapse with interneurons that travel to the higher centers in the brain
107
Central pathways for processing nociceptive information begin at the level of the ____ horn of the spinal cord
dorsal
108
The fast signals of the C fibers terminate in laminae _ and _ of the dorsal horn
I and V
109
Once these fast signals of the C fibers terminate in laminae I and V of the dorsal horn what do they do?
They excite neurons that send long fibers to the opposite side of the cord and then upward to the brain in the lateral division of the anterior-lateral sensory pathway (lateral spinothalamic tract)
110
The slow signals of the C fibers terminate in laminae _ and _ of the dorsal horn
II and III
111
Once these slow signals of the C fibers terminate in laminae II and III of the dorsal horn what do they do?
They pass through another short fiber neuron to terminate in lamina V. Here, the neuron gives off a long axon, most of which joins with the fast signal axons to cross the spinal cord and travel up the same spinal tract to the brain
112
What percentage of pain fibers terminate in the reticular formation of the medulla, pons, and mesencephalon?
75-90%
113
What are the interneuronal networks in the dorsal horn responsible for?
the transmission of nociceptive information to the neurons that project to the brain, and modulation of that information
114
What do the small number of fast fibers that bypass the brainstem and go directly to the cerebral cortex do?
these recognize and localize pain but do not analyze it
115
Which laminae of the dorsal horn is the area for convergence, summation, and projection and in effect will determine whether the pain signal is relayed upward to the brain?
Lamina V
116
What types of things can influence pain perception?
the physical effects of pain, motor activity, and emotional state
117
Although the pain intensity and the functional response to symptoms are subjective, patterns of pain response to stimulation of the pain generator are quite _____.
objective
118
What 4 things can generate referred pain?
- Convergence of sensory input from separate parts of the body to the same dorsal horn neuron via primary sensory fibers
- Secondary pain resulting from Myofascial trigger point
- Sympathetic activity elicited by a spinal reflex
- Pain-generating substances
119
What are the 5 classifications for referred pain/symptoms?
- Viscerogenic
- Vasculogenic
- Neurogenic
- Psychogenic
- Spondylogenic
120
Describe viscerogenic symptoms
These symptoms can be referred from any viscera in the trunk or abdomen
121
What are the 5 clinical characteristics of viscerogenic symptoms?
- Not evoked from all viscera
- Not always linked to visceral injury
- Diffuse and poorly localized
- Referred to other locations
- Often accompanied by autonomic reflexes such as nausea and vomiting
122
When should you suspect a visceral source of symptoms?
if the symptoms are not altered with movement or position changes
123
Vasculogenic symptoms result from what?
from venous congestion or arterial deprivation to the musculoskeletal areas
124
Neurogenic causes and symptoms may include what 4 things?
- tumor compressing and irritating a neural structure or the spinal cord or the meninges
- spinal nerve root irritation
- peripheral nerve entrapment
- neuritis
125
Emotional overtones in the presence of pain are thought to result from what?
- inhibition of the pain control mechanisms of the CNS from such causes as grief
- side effects of medications
- fear of reinjury
126
The term _____ is used to define the abnormal illness behaviors exhibited by patients who have depression, ,emotional disturbances, or anxiety states
nonorganic
127
The presence of 3 of the 5 Waddell signs has been correlated with disability. What are these 5 signs?
- Superficial or nonanatomic tenderness to light touch that is widespread and refers pain to other areas
- Simulation tests that test to see if patients report pain while performing a particular movement when it shouldn't
- Distraction tests check a positive finding elicited during the examination on the distracted patient
- Regional Disturbances in which sensory or motor disturbances have no neurological basis
- Overreaction in that the patient exhibits disproportionate verbalization, muscle tension, tremors, and grimacing during the exam
128
Spondylogenic symptoms may include what 4 things?
- severe and unrelenting pain
- fever
- bone tenderness
- unexplained weight loss
129
Interneurons in the ____ ______ function like a gate in the dorsal horn of the spinal cord to modulate sensory input
substantia gelatinosa
130
The gate closes by _____ C fiber input or _____ A fiber or mechanoreceptor input.
decreasing
increasing
131
Pain can also be gated by a descending inhibitory pathway from the brain via a mechanism called what?
central biasing
132
What is encephalin?
A pentapeptide that produces presynaptic inhibition of the incoming pain signals to lamina I-V, thereby blocking pain signals in their entry point into the cord
133
What is the negative-feedback loop in the cortex called?
The Corticofugal System
134
What does excessive stimulation of the corticofugal system result in?
a signal being transmitted down from the cortex to the dorsal horn of the level from which the input arose. This response produces lateral or recurrent inhibition of the cells adjacent to the stimulated cell, thereby preventing the spread of the signal
135
Where is the LMN located?
the dorsal and ventral roots, spinal nerve, peripheral nerve, motor neuron junction, and muscle-fiber complex
136
What does the LMN consist of?
a cell body located in the anterior gray column and its axon
137
Where can LMN lesions occur?
in the cell body or anywhere along the axon
138
What are the clinical signs of a LMN lesion?
- muscle atrophy
- hypotonus
- diminished/absent reflex
139
Where is the UMN located?
In the white columns of the spinal cord and the cerebral hemispheres
140
What are the characteristics of an UMN lesion?
- Spastic paralysis or paresis
- Little or no muscle atrophy
- Hyper-reflexive muscle stretch reflexes in a nonsegmental distribution
- Presence of pathologic signs and reflexes
141
What are the clinical signs of a UMN lesion?
- Nystagmus
- Dysphasia
- Wallenberg syndrome (the result of lateral medullary infarction)
- Ataxia
- Spasticity
- Drop attack (loss of balance with a fall without losing consciousness)
- Wernicke’s encephalopathy
- Vertical diplopia (double vision)
- Dysphonia
- Hemianopia (loss of half of the visual field)
- Ptosis (droopy upper eyelid)
- Miosis (pupils don't dilate)
- Horner syndrome
- Dysarthria
142
What type of maneuver is used to determine if the cause of the patient’s dizziness is a vestibular impairment?
Dix-Hallpike maneuver
143
What is a reflex?
a subconscious, programmed unit of behavior in which a certain type of stimulus from a receptor automatically leads to the response of an effector
144
Describe a muscle stretch reflex
It is the simplest reflexes, depending on just 2 neurons and 1 synapse, which is influenced by the GTO and the muscle spindle receptors
145
What is reflex integrity?
the intactness of the neural path involved
146
What are the 6 reflexes regularly tested?
- Biceps
- Brachioradialis
- Triceps
- Quads
- Extensor digitorum brevis
- Achilles
147
If a reflex is difficult to elicit, what type of maneuver should you perform?
Jendrassik maneuver which is a distraction technique
148
An asymmetrically depressed or absent reflex is suggestive of what?
A pathology that is impacting the reflex arc directly (peripheral neuropathy, spinal nerve root compression, or cauda equine syndrome)
149
What is a positive Babinski reflex?
great toe extension and abduction of the other toes
150
What is a positive Chaddock reflex?
extensor toe sign and abduction with stroking of the lateral foot beneath the lateral malleolus
151
What is a positive Oppenheim reflex?
extensor toe sign with stroking of the anteromedial tibial surface
152
What is a positive Schaefer sign?
extensor toe sign with a sharp, quick squeeze of the Achilles tendon
153
What is a positive Hoffman sign?
adduction and opposition of the thumb and slight flexion of the fingers when the clinician pinches the distal phalanx of middle finger
154
What is a positive test for Clonus?
more than three involuntary beats of the ankle/wrist when put into sudden extension or dorsiflexion
155
What is the Lhermitte symptom?
Patient experiences an electric, shock-like sensation that radiates down the spinal column into the UE or LE with passive flexion of the neck in the long sitting position
156
Supraspinal reflexes produce movement patterns that can be modulated by what?
descending pathways and the cortex
157
What are righting reflexes?
Processes that are oriented around supraspinal reflexes in which the main goal is maintain a constant position of the head in relation to a dynamic external environment
158
What are the 5 subcategories of righting reflexes?
- Visual righting reflexes
- Labyrinthine righting reflexes
- Neck righting reflexes
- Body on head righting reflexes
- Body on body righting reflexes
159
What makes the control of upright posture possible?
The interaction between the visual and vestibular systems and with cervical mechanoreceptors
160
What is the vestibulo-ocular reflex (VOR)?
A reflex that is simulated by movement of the head in space and creates certain eye movements that compensate for head rotations or accelerations (rotational, translational, ocular-counter rolling)
161
What are the 4 ways the VOR is tested?
- Dynamic visual acuity
- Doll’s head test
- Head-shaking nystagmus test
- Head-Thrust test
162
What does the cervico-ocular reflex do?
It serves to orient eye movement to changes in neck and trunk position
163
What does the cervicocollic reflex do?
It serves to orient the position of the head and the neck in relation to disturbed trunk posture
164
What does the vestibulocollic reflex do?
It maintains postural stability by actively stabilizing the head relative to muscles opposite to the direction of cervical spine perturbation
165
What is paresthetica?
an abnormal sensation of pins/needles, numbness, tingling, or prickling
166
What is the sensibility hierarchy from least to most complicated level of function?
- the ability to distinguish a single point stimulus from normal background stimulation (detection)
- the ability to perceive that stimulus A differs from stimulus B (innervation density)
- the ability to organize tactile stimuli according to degree, texture, etc. (quantification)
- the ability to identify objects without visual reference (recognition)
167
Where does sensation originate?
in the lateral spinothalamic tract
168
What are the 2 components of dermatome tests for sensation?
Light touch and Pinprick
169
Where does pain originate?
in the lateral spinothalamic tract
170
How do you test pain sensation?
Use two test tubes filled with hot and cold water and test to see if they can determine which is which. Temperature can be tested because impulses for temp sensation travel together with pain sensation in the LST
171
Where does pressure originate?
In the spinothalamic tract
172
Where do you test pressure?
the patient’s muscle belly
173
Where does the sensory threshold originate?
in the dorsal column/medial lemniscal tract
174
What do sensory threshold tests measure?
the intensity of the stimulus necessary to depolarize the cell membrane and produce an action potential – the ability to detect
175
What are the 2 ways in which you can test the sensory threshold?
- Vibration test using tuning fork
| - Cutaneous sensibility testing using horse hairs of varying thickness
176
Where does proprioception originate?
In the dorsal column/medial lemniscal tract
177
Where does kinesthesia originate?
In the dorsal column/medial lemniscal tract
178
How do you test movement sense (kinesthesia)?
Ask the patient to verbally indicate the direction of movement while in motion
179
Where does stereognosis originate?
In the dorsal column/medial lemniscal tract
180
How do you test stereognosis?
Ask the patient to recognize small objects of various shapes and sizes while their vision is occluded
181
Where does Graphesthesia originate?
In the dorsal column/medial lemniscal tract
182
How do you test Graphesthesia?
Ask the patient to recognize numbers, letters, or designs traced onto the skin while their vision is occluded
183
What is spasticity?
a velocity-dependent resistance to passive stretch
184
What are 2 examples of spasticity?
- Clasped-knife phenomenon: during rapid movement, initial high resistance may be followed by a sudden relaxation of the limb
- Clonus: an exaggeration of the stretch reflex characterized by cyclical, spasmodic alternation of muscle contraction and relaxation in response to sustained stretch of the spastic muscle.
185
What is rigidity?
an increased resistance to all motion, rendering body parts stiff and immovable
186
What are 2 examples of rigidity?
- Cogwheel phenomenon: ratchet-like response to passive movement
- Leadpipe rigidity: constant rigidity throughout the ROM
187
What is dystonia?
A hyperkinetic movement disorder characterized by disordered tone and involuntary movements involving large portions of the body which results in twisting and repetitive movements
188
Describe decorticate positioning
The UEs are held in flexion and LEs in extension
189
Describe decerebrate positioning
UEs and LEs are held in extension
