Exam 3: Spinal Cord, Spinal Nerves, and Reflexes Flashcards
About how many neurons are there?
100 million
The spinal cord and its associated spinal nerves contain _____ ______ that control your most …?
`Reflex circuits, most rapid reactions to environmental changes
What is gray matter?
In the spinal cord contains major of postsynaptic potentials (EPSP and IPSP)
What is white matter?
In the spinal cord contains major sensroy and motor tracts to and from the brain
The spinal cord begins as a continuation of the ______ ______.
Medulla oblongata
The spinal cord extends from the _______ ______ of the occipital bone to its termination at the _______ ________ between ____- ____.
Foramen magnum, conus medullaris, L1-L2
As the cord arises from the conus medullaris, this region is called?
Filum terminale
What is the filum terminale?
Slender strand of fibrous tissue that provides support to the spinal cord
The cauda equina also known as the horses tail are the what?
Roots of the lower spinal nerves that angle down alongside to filum terminale
The spinal cord has two enlargements, what are they?
One in the cervical are from c4-T1 and anohte rin the lumbar area between T9- T12
The cervical enlargement correlates with the ________ ______ and _______ ______ to the ______ exteremities.
Sensory inputs and motor outputs,
The lumbar enlargement handles the ____ _____ and _____ ______ to and from the ______.
Motor outputs, sensory inputs, legs
From superior to inferior, the spinal cord becomes progressively what?
Smaller
There is less and less _____ matter as we descend. Why?
White; because less and less white matter as we descend because there are fewer sensory tracts going up and there are fewer motor tracts going down
What are the protection of the spinal cord?
Bone
Meninges
CSF (cerbral spinal cord)
What are the 3 meninges?
Dura mater
Arachnoid mater
Pia mater
The dura mater is made up of lots of what type of fibers?
Collagen fibers and is tough
The arachnoid mater is made up of what?
Spiderweb like middle laber of fibers
The pia mater is…?
Delicate layer right close to the spinal cord
What are the 3 potential spaces in the spinal cord?
Epidural: outside area
Subdural: between dura and arachnoid
Subarachnoid: deep to arachnoid
What is the dura mater?
Tough outer coverung that is formed of collagen fibers
When the dura mater reaches the sacral canal, the dura mater does what?
tapers and blends wth components of the film terminal and forms the coccygeal ligament
What is the epidural space?
External to the dura mater
Anesthetics are often injected into the epidural space
Injection into thecorrect space is vital and mistakes can be vital
For fun knwo these
The arachnoid mater is the…?
Middle layer with weblike extensions
The arachnoid mater is separated from the _____ ______ by _____ ______
Dura mater, subdural space
What is the subarahnoid space?
Bewteen arachnoid and pia mater that contains CSF and blood vessels
What allows for CSF reasorption?
Arachnoid villi
What is a lumbar puncture?
Needle introduced into subarachnoid space to collect CSF
The lumbar spine needs to be flexed so can go between the spinous processes
What is the pia mater?
Delicate layer that adheres to the neural tissue that is made up of elastic and collagen fibers
What do the two _______ grooves divide the spinal cord into ____ and ______ halves.
Lengthwise, right and left
What are the two halves?
Ventral (anterior) median fissure
Dorsal (posterior) median sulcus (shallower)
What is the gray matter?
The region of spinal cord that is for integration and initiates commands
What is the white matter?
Area that carries information from place to place
The gray commissure encloses the?
Central canal
The gray commissure is the?
Connection of the lateral masses of gray matters
Overall, the gray matter reflects the amount of…?
Skeletal muscel innervation at that level
There is more skeletal muscle innervation in the?
Cervical and lumbar space
What are the portions of the gray matter in the spinal cord?
Dorsal (posterior) horns
Ventral (anterior) horns
Lateral horns
The dorsal horns are…?
Interneurons that receive somatic and visceral sensory input
Dorsal horns is the ______ site between the…?
Synapse site
First order sensroy neurons coming from the periphery to second order neurons which ascend the cord or exit back out as parts of reflex arcs
The ventral horns are the?
Somatic motor neuron cell bodies whose axons ext the cord via ventral roots
The lateral horns are the?
Cell bodies of autonomic (sympathetic) motor neruons serving visceral organs
The lateral horns are only located in the?
Only thoracic and lumbar regions
the visceral neurons reach the?
Cardiac and smooth muscle
The somatic neurons innervate?
Skeletal muscle
What is a tract?
Bundle of neuronal axons that are all located in a specific area of the cord and all traveling to the same place. Higher or lower in the brain or cord
The white matter of the cord is divided into what parts?
Dorsal (posterior) horn, ventral (anterior) horn, lateral horn
The ascending sensory tracts are travling to the ______.
Brain
Desending motor tracts are traveling to _____ _____
Spinal cord
he ventral root o the spinal cord is the _______ tract aka _____ tract containing what type of fibers?
Efferent tract, output tract, contianing somatic and autonomic/visceral fibers (axons)
What does the ventral root serves the _______ division of the PNS.
Sensroy division
The doesal root ganglia is the?
Enlargement of dorsal root that contains cell bodies of sensroy neurons
Ventral and dorsal roots are _____ and _____ to form the ______ ______ all along the spinal cord.
Short, fuse, spinal nerves
The ventral roots innervate the?
Skeletal muscels
THe dorsal roots conduct impulses from the _______ _____.
Peripheral receptors
How many pairs of spinal nerves are there?
31
HOW many of each type of spinal nerve?
8 cervical
12 thoracic
5 lumbar
5 sacral
1 coccygeal
Where do spinal nerves exit from and into?
From Central nervous system into peripheral nervous system
ONce it enters the peripheral nervous system, they immediately split into…?
3 branches
What are the 3 branches that the spinal nerve will form in the PNS?
Ventral ramus, dorsal ramus, rami communicantes
The spinal nerves are _______ of ______ and _________ peripheral axons enclosed by ______ ______.
Bundles, myelinated and unmyelinated, connective tissue
The back is innervated by ______ ______ via several _______.
Dorsal rami, branches
The ventral rami of T2- T12 are ___________ nerve supply the muscels of the _____, ___________ _____ and _______ wall.
Intercostal, ribs, anterolateral thorax, and abdomial wall
All ventral rami except for ________ form networks called plexus
T2-T12
What are the plexuses?
Cervical
Brachial
Lumbar
Sacral
What is the cervical plexus formed by?
Ventral rami of C1-C4
What does the cervical plexus innervate?
Skin and muscles of the head, neck, and shoulders, and diaphragm
What is the phrenic nerve?
Major motor nerve and sensory nerve of the diaphragm
The phrenic nerve receives fibers from the ___- ___?
C3-C5
What is the brachial pexus fromed from?
C5-C8 and T1
What does the brachial plexus give rise to?
Gives rise to nerves that innervate the upper limbs
What are the major branches of the brachial plexus?
Axillary, median, ulnar, radial
The ulnar nerve is the largest _________ nerve.
Unprotected
What does the ulnar nerve supply?
Median half of the hand
The lumbar plexus arises from the..?
Ventral rami of L1-L4
What does the lumbar plexus innervate?
Innervates the anterolateral abdominal wall, external genetalia, parts of the lower limb and psoas muscle
What are the majro branches of the lumbar plexus?
Femoral nerve
Obturator nerve
Thesacral plexus arises from the…?
Ventral rami of L4-L5 and S1-S4
What does the sacral plexus innervate?
Serves buttocks, pelvic, structures, perineum, and lower limb
The sciatic nerve is the ____ and _____ nerve.
Longest and thickest
The sciatic nerve innervates the…?
Hamstring, adductor magnus, and most muscles in the leg and foot
The sciatic nerve is composed of two nerves, what are they?
Common fibular, and tibial
What is the dermatome?
Area of skin innervated by the cutaneous branches of a singel pinal nerve
All spinal nerves except for _____, participate in dermatoems
C1
Most dermatomes overlap, so if one is destroyed what happens?
Spinal nerves will not cause complete numbness
What are inborn reflexes?
Rapid, involuntary (autonomic), predicatble motor response to a stimulus
Learned (aquired) reflexes are…?
Resulting from practice or repetition
What is the reflex arc?
Pathway that a nerve impulse follows to produce a reflex
Study the reflex arc diagram in notes
PLEASE
In a spinal reflex the integration takes place in the _____ ____ not the _____.
Spinal cord not the brain
The spinal reflexes can go in an out on the ____ or the ________ side of the cord
Same or opposite
What are the two types of spinal relexes?
Monosynaptic and polysynaptic
What is the monosynaptic spinal reflexes?
Sensory neuron with motor neuron
What is the polysynaptic spinal reflex?
Involving interneurons
