Overview of the Nervous System and Spinal Nerves Flashcards
Comprised of the neuronal cell bodies, nerve fibers, and connective tissues of the brain and spinal cord
Central nervous system (CNS)
Initiates, regulates, and coordinates body functions
CNS
The CNS communicates with other functional components of the body via the
Peripheral nervous system (PNS)
Collections of neuronal cell bodies within the CNS are called
Nuclei
The nerve fibers of the CNS are commonly arranged into discreet bundles called
Tracts
Comprised of the neuronal cell bodies, nerve fibers and connective tissues that lie outside the CNS
-conveys information between CNS and peripheral structures
Peripheral Nervous System (PNS)
Collections of neuronal cell bodies outside of the CNS are referred to as
Ganglia
Comprised of peripheral nervous tissue responsible for
carrying signals to and from skeletal muscles, tendons,
joints and skin
Somatic Nervous System
Conveys sensations of pain, temperature, tough, and proprioception from the periphery to the CNS
Somatic PNS
The cell bodies of lower somatic motor neurons are located in the
Ventral horn of spinal cord
The cell bodies of somatic sensory neurons are located in
Dorsal root (spinal) and cranial nerve ganglia
The internal organs in the main cavities of the body, especially those in the abdomen, e.g., the intestines.
Viscera
Comprised of peripheral nervous tissue responsible for
carrying signals to and from the viscera.
-conveys visceral sensations such as distension
Autonomic PNS
The Autonomic PNS is comprised of
- ) Sympathetic nervous system
2. ) Parasympathetic nervous system
Elicits the so-called “fight or flight” response, which includes pupilary dilation, increased heart rate, blood pressure, and sweating
Sympathetic nervous system
Controls digestive functions, slows the heart rate, and constricts the pupils
Parasympathetic nervous system
Both utilize two motor neurons in the peripheral path to innervate smooth and cardiac muscle
Sympathetic and parasympathetic nervous systems
The anatomic unit of the nervous system
-consists of a cell body, dendrite(s), and an axon
Neuron
Microscopically, neurons can be classified as being
-based on the number of processes associated with their cell body
Multipolar, bipolar, or unipolar
Functionally, neurons are classified as being either
Motor (efferent) or Sensory (afferent)
These neurons are multipolar and carry information away from the CNS
-cell bodies are located in the nuclei, within the ventral horn of spinal cord
Motor (efferent) neurons
These neurons are unipolar and carry information towars the CNS
-cell bodies are clustered in ganglia located outside CNS
Sensory (afferent) Neurons
Ganglia associated with spinal nerves are called
Dorsal root ganglia (spinal ganglia)
Lies within the vertebral canal extending from the foramen magnum to the level of the intervertebral disc between L1/L2 vertebra
Spinal Cord
Surrounded by three meningeal layers: dura mater (outermost), arachnoid mater (intermediate), and pia mater (innermost) and bathed in cerebrospinal fluid (CSF) that fills the subarachnoid space
Spinal cord
The spinal cord consists of
White and grey matter
Bundles of myelinated axons arranged in discreet fiber tracts
White matter
Arranged into three major horns: ventral (motor), dorsal (sensory), and lateral (autonomic motor)
Grey matter
Attach to the spinal cord via ventral (motor) and dorsal
(sensory) roots and functionally divide it into 31 spinal cord segments
Spinal nerves (31 pairs)
There are 31 pairs of spinal nerves, which comprises
8 Cervical, 12 thoracic, 5 lumbar, 5 sacral, and 1 coccygeal
Spinal nerves exit the vertebral canal through intervertebral foramen. Where do the following exit?
- ) Spinal nerves C1-C7
- ) Spinal nerve C8
- ) Thoracic, lumbar, and sacral nerves
- ) Above the vertebrate (I.e. C3 exits above C3 between C2 andC3)
- ) Below C7
- ) Below their corresponding vertebra
Spinal nerves exit the vertebral canal through
Intervertebral foramen
Each spinal nerve is attached to the spinal cord via a
1.) Ventral (motor) root
and a
2.) Dorsal (sensory) root
The ventral root carries only motor nerve fibers and the dorsal root carries only sensory nerve fibers. these roots merge to form the
Mixed (motor and sensory) spinal nerve
The spinal nerve divides into two, forming a
-also mixed nerves
Ventral ramus and dorsal ramus
What three things do dorsal rami innervate?
- ) Skin of back
- ) True back muscles
- ) Zygapophyseal joints
Innervate the remainder of the skin and skeletal muscles of the neck, trunk, and limbs
Ventral rami