Lecture 16 Flashcards
- Spinal enlargement:
- Where are the two enlargements of the spinal cord?
- widened regions of spinal cord to accommodate for innervation of the upper and lower limbs
- cervical and lumbar regions
Conus medullaris=
Cauda equine=
Filum terminale=
- the lower end of the spinal cord
- “horse tail”–> bundle of spinal nerves
- fibrous strand anchoring the spinal cord to the coccyx (NON-functional, no nerve tissue)
_________: opening in occipital bone for spinal cord
foramen magnum
Where does the spinal cord end?
At L1-L2 level
(lumbar 1-2 region)
3 layers of membranes protect the brain and spinal cord= meninges
1.
2.
3.
- the spinal cord resides within the ________ _______
- Dura mater
- Arachnoid mater
- Pia mater
- vertebral column
H-shaped GREY matter=
WHITE matter=
- somas of neurons (cell bodies)
- myelinated axons
Dorsal root= ______ signals
Ventral root= ______ signals
Ganglion=
sensory
motor
cluster of neurosomas in the PNS (somas of SENSORY neurons)
_________: cluster of neurosomas in the CNS
found in ______ matter
nuclei
gray
Organization of the gray matter in the spinal cord:
- ______ horn=
- ______ horn=
- ______ horn=
- dorsal or posterior= interneurons
- lateral= visceral (autonomic motor neurons)
- ventral or anterior= somatic motor neurons
The spinal cord is a ____-way impulse conduction pathway and a ______ center
two; reflex
The _____ matter is composed primarily of myelinated axons, organized in _______, each of which contains ascending or descending axon ______ related to specific functions
white; columns; tracts
Tracts:
bundles of CNS axons that share a common origin, destination, and function
- ascending tracts contains _______ information which is sent to the _____
- descending tracts contains _______ information that comes from the __________ of the brain and sends it to __________ cord
- sensory; brain
- motor; cerebral cortex; spinal
3 main types of ascending tracts
1.
2.
3.
- Spinothalamic tract
- Dorsal column-medial lemniscus system
- Spinocerebellar pathway
Two pathways of spinothalamic tract:
- __________: temperature and pain
- __________: pressure and crude touch
- both finish in _______
- lateral
- anterior
- thalamus
Fasciculus
bundle of axons
____________: the ability to sense position (posture) and perform movements
proprioception
Dorsal column-medial lemniscus system
- fasciculus gracilis (medial):
- fasiculus cuneatus (lateral):
-what type of info do these both carry?
- info from lower body
- info from upper body
- conscious proprioception, vibration, tactile sensation, and two point discrimination
Spinocerebellar pathway
- Golgi tendon organs, muscle spindles, joint capsules –> __________
- doesn’t ascend to cerebral cortex
- ___________ proprioception
- cerebellum
- unconscious
Types of neurons in spinothalamic tract
1.
2.
3.
- First order neuron
- Second order neurons
- Third order neurons
First order neuron
- location of cell bodies:
- where they end:
- dorsal nerve root ganglion
- substantia gelatinosa in dorsal horn (synapse to second order neurons)
Second order neurons:
- location of cell bodies:
- where they end:
- their fibers form the ________ tracts
- dorsal horn
- thalamus
- ascending
Third order neurons
- location of cell bodies:
- where they end:
- thalamus
- cerebral cortex of the brain
Spinothalamic pathways ________ which means they cross to the other side within the spinal cord
decussate
spinal nerve
a bundle of axons in the PNS that contain sensory and motor nerve fibers
The _______ (sensory) and ________(motor) roots fuse to form a spinal nerve
dorsal; ventral
Nerves have many _______ (bundles of axons) which are wrapped around _______
fascicles; perineurium
3 connective tissue layers of nerve
1.
2.
3.
- Epineurium: covering the peripheral nerve
- Perineurium: around 1 fascicle
- Endoneurium: inside fascicle; between axons
2 major group of nerves:
-_____ pairs of cranial nerves: some are sensory or motor, most are mixed
- _____ pairs of spinal nerves: all are mixed
12
31
__________= areas of sensation located in the skin
a ___________ is a digram of the cutaneous (skin) regions innervated by each spinal nerve
dermatomes
dermatome map
following a traumatic injury, the clinician can test dermatomes to determine the presence and the extent of a ______ ____________ ______
spinal cord lesion
nerve plexus:
a branching network of intersecting nerves; located in the spinal cord
5 spinal nerve plexuses
1.
2.
3.
4.
5.
- Cervical plexus
- Brachial plexus
- Lumbar plexus
- Sacra plexus
- Coccygeal plexus
reflexes are:
- ______: involve few, if any, interneurons and minimum synaptic delay
- _______: occur without intent and are difficult to suppress
- _______ : occur essentially the same way every time (automatic)
reactions of ________ or _______ to stimulation
quick
involuntary
stereotyped
glands; muscles
Visceral reflexes:
involve a glandular or non-skeletal muscular response carried out in internal organs such as heart, blood vessels, or structures of the GI tract
Somatic reflexes:
reflexes involving the somatic nervous system innervating skeletal muscle
Spinal reflex:
somatic reflexes mediated by the spinal cord
reflex arc:
the neural “wiring” pathway of a single reflex
A reflex arc
1. stimulus activates _________
2. Nerve impulse travels through sensory neuron to _______
3. Nerve impulse is processed in the integration center by __________
4. Motor neuron transmits nerve impulse to _______
5. ________ responds to impulse from motor neuron
- receptor
- spinal cord
- interneuron
- effector
- effector
Poly=
Mono=
- multiple synapses
- only one synapse
polysynaptic reflexes contain __________, while monosynaptic reflexes DO NOT
interneurons
The Stretch Reflex (aka _________)
- type of reflex=
- regulates skeletal muscle ________
- stretching of muscle detected by ________ ________
myotactic
- monosynaptic reflex
- length
- muscle spindles
Stretch reflex example
- Patellar (Knee-jerk) reflex
the stimulus (the tap on the patellar ligament stretches the quadriceps femoris muscle and initiates ________ of the muscle, thereby extending the knee joint
contraction
The Golgi Tendon Reflex
- reflex type:
- it is a response to……
- it protects the muscle from excessively _______ loads by causing the muscle to relax and drop the load
- tension is detected by….
- polysynaptic since inhibitory interneurons participate
- excessive tension on the tendon
- heavy
- Golgi tendon receptors
Alpha motor neurons (also called lower motor neurons):
innervate skeletal muscle and cause the muscle contractions that generate movement
The flexor (________) reflex
- the quick _______ of flexor muscles resulting in the withdrawal of a limb from an injurious stimulus
- initiated by a ______ stimulus
- flexor muscle= ________
- extensor muscle= _______
withdrawal
- contraction
- painful or noxious
- contracts
- relaxes
The crossed extension reflex
- _________ and _______ that limb and enables you to keep your balance
- flexors= _________ (motor neurons _______)
- extensors= ________ (motor neurons ________)
- extends and stiffens
- relaxes; inhibited
- contraction; activated
For the crossed extension reflex to exist the _______ reflex must coexist (occur)
flexor (withdrawal) reflex
