Nervous System - Anatomy 08/11/17 Flashcards
What does the CNS do?
Integrate signals for the body to be able to perform higher mental functions
What does the PNS do and what is it composed of?
Relay the signals to and from brain and spinal cords; includes 12 cranial nerves and 31 pairs of spinal nerves
What is the SNS responsible for?
Voluntary actions and SENSATION. Supplies skeletal muscle
What is the ANS responsible for?
Involuntary nervous system supplying smooth involuntary muscle, glands, and viscera
What is another name for the ANS?
Visceral Nervous System
What is the ANS composed of?
Autonomic parts of CNS and PNS
What composes nervous tissue?
Neurons and neuroglia
What kind of cells are neurons? Neuroglia?
Nerve cells; glial cells
What are glial cells?
Surround neuron and provide support
What unit are neurons for the nervous system? What are they specialized for?
Functional and structural units; rapid communication
What 3 things are neurons composed of?
- Cell body
- Axon
- Dendrites
Axon
Single appendage and carries impulses away from cell body
What can some axons have? Why?
Myelin sheath to increase velocity of communication
Dendrites
Multiple extensions and carry impulses to the body
Where do neurons communicate and how?
Synapses; chemical neurotransmitters
What are neuroglia? Are they more abundant than neurons?
Support, insulate, and nourish (Sin) neurons; yes
What two things do neurons have in the CNS?
- Nucelus
2. Tract
CNS Neuron Nucleus. What does it form?
Collection of nerve cell bodies. Gray matter
CNS Neuron Tract. What does it form?
Bundle of nerve fibers connecting CNS nuclei. White matter.
What 2 neurons are in the PNS?
- Ganglion
2. Peripheral nerves
PNS Neuron Ganglion
Collection of neuronal cell bodies outside of CNS
PNS Neruon Peripheral Nerve
Bundles of nerve fibers, their coverings, and vessels
What are the 5 types of vertebrae?
- Cervical
- Thoracic
- Lumbar
- Sacral
- Coccygeal
How many cervical?
7
How many thoracic?
12
How many lumbar?
5
How many sacral?
5
How many coccygeal?
4
How many pairs of spinal nerves?
31
How many cervical nerves?
8
How many thoracic nerves?
12
How many lumbar nerves?
5
How many sacral nerves?
5
How many coccygeal spinal nerves?
1
Where does each pair of nerves leave?
Vertebral canal through the intervertebral foramen between pedicles of adjacent vertebrae
Where does the C4 spinal nerve exit? C7?
The C4 spinal nerves exits in the IV foramen ABOVE C4 vertebrae. C7 spinal nerve exits in the IV foramen above c7 vertebrae
What about C8 spinal nerve?
Above T1 - now everything shifts by 1
Where does L4 exit?
Above L5
What 2 things does a spinal nerve have in the anterior view?
White/gray (H shaped) matter
pHAG
The H=shaped Gray matter has the anterior (ventral) and posterior (dorsal) horns
Efferent
Motor
Afferent
Sensory
What part of the spinal nerve is unique to the posterior horn of the spinal nerve?
Spinal Ganglion
CANS
Anterior horn arises from the CNS
Anterior Horn is motor or sensory?
Motor
Posterior Horn is motor or sensory?
Sensory
More myelin is what color?
White
What type of muscle is associated with the anterior horn?
Voluntary, skeletal muscle
How do neurons return sensory information?
Via the same level of the spinal cord at the spinal nerve of the POSTERIOR root
What is the posterior spinal/dorsal root ganglion for?
Houses cell bodies of the sensory neurons lateral to the IV foramen
What does the posterior ramus supply?
Mixed motor/sensory spinal nerves to the:
- Synovial joints of vertebral column
- Overlying skin
- Deep muscles of back
What does the anterior ramus supply?
Much larger area than posterior. Supplies mixed nerve fibers to the rest of the body wall and upper/lower limbs
Where are the cell bodies of the motor neurons?
Anterior horn
What is “innervation”?
Arrangement or distribution of nerves to an organ or body body
Define dermatome.
Strip of skin innervated by sensory fibers of a single spinal nerve
What are 3 diagnostically important dermatomes?
a) T4- Nipple
b) T10 - Umbilicus
c) L1 - Lowest anterior body wall ignoring male body part
Define myotome
Muscle innervated by a single spinal nerve
What is a clinical correlation for dermatomes and myotomes?
Herniated disks
Define conus medullaris
End of spinal cord, expanded area
In the embryo and fetus, how long does the spinal cord run?
The entire length of the vertebral column
At birth, where does the spinal cord extend to?
L2/L3 vertebral levels
How about the adult?
L1/L2
Define filum terminale
Anchors spinal cord to coccyx by a cord
Define cauda equina
Nerve roots dropping off bottom of spinal cord
Does concordance decline as your move down the spinal cord?
Yes
Define meninges.
3 membraneous layers that cover the spinal cord
What else is related to the meninges? Functions?
Cerebrospinal fluid (CSF); protect brain and spinal cord
What are the 3 layers to the meninges?
- Pia mater
- Arachnoid matter
- Dura matter
Pia matter forms what?
Denticulate ligaments at attachments
Arachnoid matter adheres where?
Close to dura matter in life
What does arachnoid matter contain? What is its function?
Subarachnoid space (between pia and arachnoid). Contains CSF and potential space between pia and arachnoid
What is the toughest layer?
Dura matter (outermost, thicker)
Where does the dura matter end? What else ends there?
S2. CSF in subarachnoid space
Where should you withdraw CSF in an adult?
Below L1/L2
What is the epidural space?
Separates meninges from vertebral column
What is the epidural space filled with?
Fat
What does the pia matter form to anchor the spinal cord?
Denticulate ligaments
What does the pia matter do so its not prone to spinal cord injuries?
Condensation down to the coccyx that forms the filum terminale that holds the spinal cord in place
Where does the Somatic Nervous System (SNS) supply motor and sensory information to?
Entire body except:
- Viscera
- Smooth muscle
- Glands
What is another name for the Autonomic Nervous Systen? (ANS)
Visceral nervous system
What does the ANS do?
Supply motor and sensory innervation to cardiac muscles, smooth muscles in walls of blood vessels and organs, and glands
What can the ANS efferent nerve fibers be divided in to?
Parasympathetic and Sympathetic Nervous Systems
Sympathetic Nervous System
Catabolic (fight or flight)
Define Catabolic
To break down
Parasympathetic Nervous System
Anabolic. Promotes normal functions and energy conservations
Where is the presynaptic neuron located?
Gray matter
Where is the postsynaptic neuron located?
Autonomic ganglia outside CNS
What is another term for synaptic?
Pre/Post “ganglionic” neuron
Where are the presynaptic sympathetic cell bodies located?
Intermediolateral cell columns (IML) or nucle of spinal cord that extends from T1-L2
Where are the postsynaptic sympathetic cell bodies located?
Paraverterbral ganglia
What does the paraverterbral ganglia do?
Link together to form sympathetic trunk
Define plexus
Network of nerves or vessels in the body
Define ganglion
Structure containing a number of nerve cell bodies
What is the exception for postsynaptic fibers exiting through branches of aorta?
Seprarenal gland
How do visceral afferents return sensations?
Via white rami
Where are visceral afferent cell bodies?
Spinal ganglion
Do visceral afferents synapse outside CNS?
No