Provides almost the entire nerve supply to the shoulders and upper limbs

The sacral plexus supplies the buttocks, perineum, and lower limbs.

CNS Flashcards by Jocelyn Leclaire

The spinal cord is protected by:

Bone (vertebrae)
Connective tissue (meninges)
Fluid (cerebrospinal fluid)

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The meninges

three layers of connective tissue coverings around the brain and spinal cord

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Three meninges layers

Dura mater (outermost tough layer)
Arachnoid mater (middle layer)
Pia mater (innermost)

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Cerebrospinal fluid (CSF)

circulates in the
subarachnoid space (between the arachnoid and pia mater).
o CSF cushions and protects the nervous tissue of the CNS

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Epidural space

o space between dura mater and wall of vertebral canal and wall of the skull
o Contains fatty and loose connective tissue

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Subdural space

o Very shallow space between dura mater and arachnoid matter
o Contains some interstitial fluid but not CSF

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Subarachnoid space

o space between arachnoid and pia mater
o contains cerebrospinal fluid (CSF)

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Grey Matter

cell bodies, dendrites, unmyelinated
axons

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White Matter

myelinated axons

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Posterior (Dorsal) horns

incoming sensory
signals

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Anterior (Ventral) horns

outgoing motor signals

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Spinal nerves

are part of the peripheral nervous system (PNS)
have both motor and sensory function and therefore called “mixed” nerves

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Nerve organization

organized into fascicles and have 3 connective tissue linings

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Epineurium

Around the entire nerve

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Perineurium

Layer around each nerve fascicle

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Endoneurium

Around each individual axon

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Nerves of the Spinal Cord

31 pairs of spinal nerves
8 cerv, 12 thorax, 5 lumbar, 5 sacral, 1 coccyx

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Four nerve plexus

cervical, brachial, lumber, sacral

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Plexus

nerve fibers from different spinal nerves are sorted and
recombined to coordinate a specific body part

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Cervical plexus (C1-C5)

Supplies the skin and muscles of the head, neck, superior portion of the shoulders and chest, and diaphragm

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Brachial (C5-T1)

Provides almost the entire nerve supply to the shoulders and upper limbs

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Lumbar (L1-L4)

The lumbar plexus supplies the anterolateral abdominal
wall, external genitals, and part of the lower limbs

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Sacral (L4-S4)

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The sacral plexus supplies the buttocks, perineum, and
lower limbs.

Cauda equina

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“horse’s tail”
* Collection of spinal nerves arising from inferior
portion of spinal cord
* Contributes to ability to move and feel sensation in
the legs

White matter function in spinal cord

conduct nerve impulses to and from the brain

Gray matter function in spinal cord

receives and integrates incoming and outgoing information and performs spinal reflexes

The pathway followed by nerve impulses that produce a reflex is known as

a reflex arc

four major parts of the brain

o Brain stem o Diencephalon o Cerebrum o Cerebellum

Cerebrospinal Fluid

clear, colorless liquid produced in the choroid plexus of the ventricles within the brain.

CSF function

The spinal cord and brain are lubricated and protected by CSF CSF carries oxygen, glucose, and other chemicals to neurons and neuroglia and removes their wastes and toxic substances

brain stem

(1) Medulla oblongata (2) Pons (3) Midbrain

Brain stem functions

cardiovascular and respiratory regulation and coordinates movement of head, eyes and trunk. Contains many sensory cranial nerves and nerves for motor pathways

Reticular formation

Broad region imbedded in the brainstem and extending into the diencephalon Consists of ascending sensory and descending motor function

Descending RAS

The descending portion of the RAS has connections to the cerebellum and spinal cord and helps regulate muscle tone, as well as HR, BP and RR.

Ascending reticular formation

ascending portion of the reticular formation is called the reticular activating system

Reticular Activating System (RAS)

* Projects to the thalamus and cerebral cortex * Many stimuli (visual, auditory, pain, touch, proprioception) * Keeps us aware of the position of our body parts * Visual, auditory and mental activities stimulate the RAS to maintain consciousness

Major regions of the diencephalon include

Thalamus, Hypothalamus and Pineal gland

The Cerebellum

The cerebellum occupies the inferior and posterior aspects of the cranial cavity and consists of two hemispheres

The cerebral cortex

outer layer of cerebrum composed of gray matter which contains billions of neurons o Gyrus, fissures, and sulci can be identified on the cortex

corpus callosum

connects the right and left hemispheres of the cerebrum

Gyrus:

ridge

Fissures:

deep grooves between ridges

The cerebrum can be divided into

* Frontal lobe * Parietal lobe * Temporal lobe * Occipital lobe * Insula

Functional Areas of the Cerebrum

Cerebral Cortex consists of sensory, motor and association areas

Association area of cerebrum

large area of all cerebrum lobes that deals with more complex integrative functions such as memory, emotions

Limbic System

A ring of structures on the inner border of the cerebrum and encircling the upper part of the brainstem and the corpus callosum The limbic system governs emotional aspects of behavior

Decussation of Pyramids

superior to the junction of the medulla with the spinal cord, 90% of the axons in the left pyramid cross to the right side and vice versa

Result of decussation of pyramids

Each side of the brain controls voluntary movements on the opposite side of the body

Left hemisphere

important for spoken and written language, numerical and scientific skills, and reasoning

Right Hemisphere

more involved with spatial and pattern recognition, emotional content, music and art awareness

Circle of Willis

acts to provide collateral blood flow between the anterior and posterior circulations of the brain, protecting against ischemia

Importance of Blood Flow to the Brain

The brain utilizes about 20% of the body’s oxygen supply

Lack of oxygen → within 1 -2 minutes

mental function is impaired

Lack of oxygen → within

4 minutes → permanent injury

Glucose from blood enters the brain by?

facilitated transport

Circumventricular organs (CVOs)

small regions of the brain that lack the BBB * Allow the brain to monitor chemical make-up of blood more easily (hypothalamus, pineal gland, pituitary gland)

CNS Flashcards

(56 cards)