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Terms in this set (45)
The control center allowing the body to react to the environment
Comprised of: Brain, spinal cord, nerves and ganglia
Communication is accomplished with electronic impulses
There are Three different ways it is classified:
Structurally (central and peripheral)
Impulse (Sensory and motor)
Functional (Somatic and Autonomic)
Central Nervous System (CNS) - the control center
Brain and spinal cord
Peripheral Nervous System (PNS) - all the nerve processes connecting to the CNS
Cranial and Spinal nerves
Takes into account the activities that are directed by the nervous system
Somatic Nervous System (SNS)- conscious, voluntary information from the CNS to the skeletal muscles
Autonomic Nervous System (ANS)- carries involuntary information (sensory and motor) to smooth muscle, cardiac muscle, and glands of the body
Involves 2 nerve cells to reach the target
Takes into account the impulses (sensory or motor) carried by the nerves and the direction they travel
Afferent System (Sensory)- conducts information from the periphery to the central nervous system
Efferent System (Motor) - nerves traveling from the central nervous system to a peripheral structure - produces a motor activity
Nerve Cells - the Neuron
Normal cell (nucleus, plasma membrane, cytoplasm, mitochondria...)
Modified cell shape - 4 distinct parts:
Soma (cell body) - contains the nucleus, this is where the electronic impulse starts
Dendrites - multiple processes acting as the receptor portion of the neuron
Axon - the long, thin extension of the neuron. Electric impulses travel down the axon from the soma to the synaptic bulbs
Synaptic knobs - special ending of the neuron that synapses with the target of the electric impulse
A lipoprotein forming a sheath around nerves processes (can be axons or dendrites)
Function to increase the speed of the electric impulses down the length of the axon
A myelinated nerve fiber appears white in color.
White matter - region of the CNS in which all the neurons are myelinated
Gray matter - region of the CNS in which all the neurons are NOT myelinated
Calvarium - the "skull-cap" that covers the brain
Made up of several different bones (occipital, parietal, temporal and frontal)
The portion of the CNS that is contained in the skull
Functionally divided into:
Forebrain (Cerebrum and diencephalon)
Largest part of the brain and performs the higher functions.
Comprised of lobes
responsible for interpreting special senses, integrating multiple actions, recalling memories, and many other "higher-thoughts" like emotions and logic.
Divided into cerebralhemi-spheres (right and left)
Longitudinal Cerebral Fissure - an indentation down the dorsal midline that divides the two hemispheres
Grooves (aka: sulcus, pl=sulci) - the indentations in the surface of the cerebrum.
The longitudinal cerebral fissure is a LARGE groove
Gyrus (pl=gyri) - the convex cerebral brain tissue which extends out between the grooves
White matter and Gray matter
White matter - areas that have myelinated neurons
Gray matter - neurons do not have myelin
BRAIN- the EXTERNAL neurons are comprised of GRAY matter. And the internal white matter resembles a tree.
SPINAL CORD the EXTERNAL neurons are comprised of WHITE matter. And the internal gray matter resembles a butterfly
- so to keep them straight - Remember the sentence, "The Gray Butterfly flies up to the White Tree"
Corona Radiata describes the pattern which the white matter radiates out toward the gray matter cortex of the cerebrum.
Frontal Lobes -
Located at the rostral end of each cerebral hemisphere
motor activity as well as higher thoughts (logic and emotions)
Located in the middle between the frontal and occipital lobes
involved in somatosensation (sensing the surface of the body).
Located under the temporal bone, ventral to the frontal and parietal lobes
involved in the sense of hearing or "audition"
Located at the caudal end of the cerebrum
involved in the sense of sight or "vision"
This is the white (myelinated) connection between the two hemispheres of the cerebrum.
Best seen on hemi-section.
Located ventral to the cerebrum and dorsal to the midbrain
Located just caudal to the cerebrum (looks like a mini brain)
Has bilateral symmetry, lacks a central groove
Responsible for proprioception (knowledge about where your body is in space)
White matter is INTERNAL (like the cerebrum) - looks like a tree, called Arbor Vitae (tree of life)
Located ventral to the cerebrum and the cerebellum and rostral to the spinal cord.
Organizes the information going to/from the higher brain centers
Controls the maintenance of body temperature at a set point
Hunger, thirst and sleeping
Diencepahlon (rostral brainstem)
Optic Chiasm (brainstem)
Located on the ventral aspect of the brainstem (immediately cranial to the hypothalamus)
Looks like a white X
This is part of the visual pathway.
Some of the neurons from the right cranial nerve cross to the left brain at this location
Proportion of crossing neurons is relative to binocular vision
Deeply located two oval masses (paired left and right) in the cranial brainstem.
On the sagittal section - the thalamus appears to be a white circle just below the corpus callosum
Functionally this is the relay center for the entire brain
This is the most ventral portion of the brainstem, located underneath the thalamus.
Functions: maintaining homeostasis of the body
Hunger, thirst, regulating body temperature,
Heart rate, blood pressure, gastrointestinal motility and secretions
Regulates the pituitary gland with hormones
The bulge between the midbrain and the medulla oblongata.
Bridges the spinal cord and the brain
Medulla Oblongata (brainstem)
The caudal most part of the brainstem - continues caudally as the spinal cord
The other component of the CNS down the spine (in addition to the brain)
A long thin tubular bundle of nervous tissue and support cells that extends from the medulla oblongata in the brainstem to the lumbar region of the vertebral column
The central opening in every vertebra through which the spinal cord travels
Between each articulating vertebrae - this is the opening on the L and R lateral sides.
Spinal nerves exits through the intervertebral foramen
The protective tissue layers which surround the spinal cord and brain.
Function: protect the CNS
The inner most (closest to the spinal cord/brain) meninge
Basically adhered to the surface of the underlying CNS
On the brain, the pia mater follows the contours down into the grooves
Extremely thin and fragile membrane (almost invisible)
Middle layer of the meninges
Called arachnoid because it resembles "spider web" in appearance
Has delicate fingerlike projections to the pia mater
Adhered to the overlaying dura mater
Does not follow the grooves of the brain with the exception of the longitudinal fissure between the hemi-spheres
Below the arachnoid mater is the arachnoid space - which contains the cerebral-spinal fluid
The outer most layer of the meninges
A tough, fibrous, white connective tissue layer
Any nerve that branches off from the spinal cord
Exit the vertebral column via the intervertebral foramen
Ganglion (pl. ganglia)
Small, ball-like collections of nervous tissue
Houses the synapses and/or cell bodies of neurons
Example: dorsal root ganglia (spinal nerve)
Natural thickening of the spinal cord at the level of the thoracic limbs
Due to large number of nerves in this area
Thickening of the spinal cord in the lumbar region due to the pelvic limbs
Translation = "horse tail"
At the distal end of the spinal cord it breaks up into smaller strands
Cranial Nerves -12
nerves that emerge directly from the brain (including the brainstem)
10 of 12 of the cranial nerves originate in the brainstem
numbering of the cranial nerves is based on the order in which they emerge from the brain, front to back
Paired (left and right)
CN 1 - Olfactory Nerve
Comes off the cranial ventral aspect of the cerebrum
Connects to the olfactory bulb
Actually a collection of small nerves
Sensory information only
CN -2 Optic Nerve
transmits visual information from the retina (eye) to the brain
Sensory information only
CN - 3 Oculomotor Nerve
enters the orbit via the superior orbital fissure
innervates muscles that enable most movements of the eye and that raise the eyelid
CN -4 Trochlear Nerve
innervates only a single muscle: the superior oblique muscle of the eye(rotates eye in and down)
The trochlear nerve is unique among the cranial nerves in several respects:
It is the smallest nerve in terms of the number of axons it contains.
It has the greatest intracranial length.
It is the only cranial nerve that exits from the dorsal (rear) aspect of the brainstem.
It innervates a muscle, Superior Oblique muscle, on the opposite side (contralateral) from its origin.
CN -5 Trigeminal Nerve
responsible for sensation in the face and motor functions such as biting and chewing
Called trigeminal because it almost immediately splits into three nerves
it is the largest of the cranial nerves
Sensory and motor nerve
CN - 6 Abducens Nerve
controls the movement of the lateral rectus muscle in humans, responsible for moving the eyeball laterally (away from midline)
also innervates the retractor bulbi muscle, which can retract the eye for protection
Directions of "eye wander" following paralysis of specific cranial nerves:
B. oculomotor (CN3)
C. abducens (CN6)
D. trochlear (CN4)
CN -7 Facial Nerve
controls the muscles of facial expression
taste sensations from the anterior 2/3 of the tongue
Motor and sensory
CN-8 Vestibulocochlear Nerve
transmits sound and equilibrium (balance) information from the inner ear to the brain.
cochlear nerve, carrying information about hearing
vestibular nerve, carrying information about balance
CN-9 Glossopharyngeal Nerve
motor to the muscles of the pharynx
innervates the parotid gland
sensory and taste to the caudal 1/3 of the tongue
CN-10 Vagus Nerve
innervation to most laryngeal and pharyngeal muscles (vocalization)
Also provides involuntary innervation to almost all thoracic and abdominal viscera
slow the heart rate, increase intestinal and glandular activity, and relax the sphincter muscles)
Taste from the epiglottis.
Both sensory and motor
CN-11 Accessory Nerve
supplies the sternocleidomastoid (muscle tilts and rotates the head)and trapezius muscles (shrug the shoulder)
CN12 - Hypoglossal Nerve
innervates all the extrinsic and intrinsic muscles of the tongue
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