A) Extraction of CSF from the epidural space.
B) The fluid is studied looking for elements such as WBC, antibodies and blood which should not be there. It is also tested for abnormal chemical levels.
Describe the size, shape, & length of a spinal cord.
Tracts are a bundle of axons in the CNS that are relatively uniform w/ respect to size and the info they carry.
Nerves are bundles of axons or nerve fibers, along with the assoc. blood vessels and connective tissues in the PNS that carry sensory info and motor commands.
Spinal roots are spinal nerve attachments to the cord. They can be either dorsal or ventral roots.
Where are the cell bodies for the neurons exiting the cord through the ventral roots
Dorsal and ventral roots come together to make nerves therefore resulting in nerves having both sensory and motor neurons
A ramus is a spinal nerve branch. A dorsal ramus is the branch on the dorsal side after the dorsal and ventral roots mix. A ventral ramus is the branch on the ventral side after the dorsal and ventral roots mix. The dorsal ramus innervate skin and skeletal muscles of the back while the ventral rami innervate the ventrolateral body surface, structures in the body wall and the limbs.
What are dermatomes and why are they clinically useful?
An area of the skin innervated by sensory fibers from a single spinal nerve. For diagnosing damage or infection of a spinal nerve or dorsal root ganglion by a characteristic loss of sensation in corresponding region of the skin.
Interwoven network of ventral rami of adjacent spinal nerves. Because they are comprised of ventral rami, they contain both sensory and motor fibers.
Cervical– head, upper shoulders and phrenic nerve
Brachial– upper limbs
Lumbar– anterolateral abdominal wall, genitals, & part of legs
Sacral– sciatic nerve, buttocks and most of lower limbs
Cervical plexus – phrenic nerve
Brachial plexus - musculocutaneous nerve
Lumbar plexus – genitofemoral nerve, femoral nerve & the lateral femoral cutaneous nerve
Rapid, automatic responses to specific stimuli. Reflexes preserve homeostasis by making rapid adjustments in the fxn of organs or organ systems.
Define, compare/contrast cranial & spinal reflexes.
Somatic controls skeletal muscle contractions & include superficial and stretch reflexes.
Visceral controls actions of smooth & cardiac muscles as well as glands.
Innate is genetically or developmentally determined
Polysynaptic involves multiple synapses (2 – 100’s)
What is a reflex arc and what are the 5 basic
components of it?
The complete path of a single reflex from start to finish. Receptor, sensory neuron, integration center, motor neuron and effector.
What happens at each step in the arc?
Chpt 13 448
Ipsilateral reflex arc is a reflex involving everything on the same side of body. (Everything = stimulus, processing & response)
Contralateral reflex arc is a reflex involving stimulus, processing or response between both sides of the body.( Ex:Balance)
What is a stretch reflex (what happens)?
Prevents muscle from over stretching. Muscle spindle detects overstreching, triggers stretch reflex to prevent pulls or tears. – tells muscle to contract when getting too long!
What type of injury does a stretch reflex protect against?
A) What types of cells serve as receptors?
B) Is it monosynaptic or polysynaptic?
C) Is it ipsilateral or contralateral?
A)Sometimes it is the dendritic portion of neurons, sometimes it is specialized cells separate fromthe sensory neurons. The receptors in stretch reflexes are called muscle spindles.
What types of stimuli might initiate a withdrawal?
Is the withdrawal reflex Ipsilateral or contralateral?
Give examples of a couple withdrawal reflexes at work.
What happens in a crossed extensor reflex?
Works with the withdrawal reflex when the motor response occurs on the opposite side
Triggered by same sensory neuron(s) as withdrawal reflex
What is the purpose of the crossed extensor reflex?