Study guide midterm 1 Flashcards
Terminal button
Site of synapse for an axon. Where it releases it’s neurotransmitter to either a dendrite, soma, or axon of another/multiple neuron(s).
Types of neurons and roles
Multi- most common in the CNS. Motor.
Bipolar- retina. Eyes, ears and nose.
Unipolar- Most common in the PNS. Main sensory neuron. Dendrite and axon “share” a process.
Peripheral nervous system
Cranial nerves (except 1 and 2 because they are covered with meninges), axons of some spinal nerves, peripheral nerves, and neuromuscular junctions.
Nerve layers and connective tissues
Endoneurium covers neuron/fiber. Bundle of this creates fascicle. Fascicle is covered by perineurium. Bundles of fascicles are covered by epineurium and also include fat, blood vessels and schwann cells. This is a neuron.
Neural injury. What happens to neuron?
Severe damage or immediate fatal injury= little change in cell morphology. Quickly disintegrates.
Less severe neural injury. What happens?
Swelling in soma, displacement of nucleus, movement of nussl bodies (rER) to the periphery. If cell survives, all will go back to normal. If not, cytoplasm will turn dark and followed by disintegration of all organelles and the cell.
Dead neurons are removed from the CNS by ___ and in the PNS by ___
CNS by microglia and in the PNS by macrophages
Axon injuries
Axon injuries proximal to the soma are usually more severe for the cell compared to those that are distal. Distal injuries are likely to only affect part of the axon.
Pia matter contains
Collagen and elastic fibers. Very delicate layer of the connective tissue.
Where does the CNS contain connective tissue?
The meninges and in the outer layer of blood vessels.
3 types of hematomas
- Epidural. Above the dura. Shearing of artery. Commonly due to the middle meningeal artery in the pterion. Since it is an artery, there is high pressure and progresses quickly.
- Subdural. Underneath the dura. Shearing of vein. Commonly the emissary veins that pass through the skull. Less pressure, less progressive.
- Subarachanoid. Rare and usually due to cerebral aneurysm that has ruptured. Blood mixes with CSF and will raise pressure.
Visceral nervous system
Autonomic NS
How memories are formed
Afferent signals from all over the body enter the CNS and are organized there in such a way that yields our perceptions (correlations of signals) and these perceptions are stored in the CNS as memories.
Somatic efferent and afferent
Visceral efferent and afferent
Somatic afferent- General senses and special senses such as vision, hearing.
Somatic efferent- Innervation to skeletal muscles
Visceral afferent- Receptors from glands, blood vessels, viscera/internal organs and other special senses such as smell and taste.
Rami comunications
Neural fibers of the sympathetic division of the autonomic NS.
Sympathetic ganglion
Carries sympathetic division of ANS and PNS. Carries some components of the somatic division of the PNS
Cortical magnification
Areas with smaller, densely packed receptive fields. hands, feet, lips.
Purpose of some receptive fields being excitatory and the surrounding being inhibitory
Allows for better resolution
some receptors in the retina have the opposite configuration
Dermatomes
Each spinal nerve carries somatic sensory information from a specific area of the skin on the surface of the body. A dermatome is that area of skin supplied by a single spinal cord level. There is slight overlapping, but mostly defined. Can be used to localize lesions to a specific spinal nerve.
Myotomes
portion of the skeletal muscle innervated by a single spinal cord level. More difficult to isolate to a single spinal nerve because skeletal muscles are usually innervated by nerves derived from more than one spinal cord.
Muscles that move the 1. Shoulder 2. elbow 3. hands are innervated by which spinal nerves?
Shoulder- C5 and 6
Elbow- C6 and 7
Hands- C8 and T1
What spinal cord region is a nerve plexus not present?
The thoracic region does not have a nerve plexus.
Spinal nerve plexus
Extensive branching and cross joining of neighboring anterior rami.
Key somatic plexuses
- Cervical plexus to the neck and back of head. Formed from anterior rami of C1-C4.
- Brachial plexus formed from anterior rami of C5 to T1. Serves the chest, shoulder, arms, and hands.
- Superior portion injured when head and neck are pulled away from arm. “Waiter tip” position. Hand still has muscle movement.
- Inferior portion of the plexus injured from pulling arm. Innervation to hand is compromised. Claw grip presentation. Hand still has innervation.
When do pt’s demonstrate waiter tip position and claw grip position?
Waiter tip- when they damage superior portion of the brachial plexus.
Claw grip- When they damage the inferior portion of the brachial plexus. Arm and shoulder still have innervation.
What part of the body is not considered a dermatome
C1- motor only
