Module 2

What do autonomic nerves provide?

Motor innervation of smooth muscle, glands, and cardiac muscle

Were do autonomic nerves branch from?

cranial or spinal nerves

Autonomic nerves carry sensory info from

visceral structures

Where do most auto nerves carry sensory info from?

visceral structures they supply

How are suto nerves organized?

into sympathetic and parasympathetic divisions, which use 2 neurons
in series to provide motor innervation to target tissues


a collection of neuron cell bodies that are found somewhere outside
the brain or spinal cord. Can be autonomic or sensory

What do all autonomic pathways utilize?

two neurons in the peripheral nervous system

Most __________ carry sensory info back to the brain from the
visceral structure innervated

autonomic nerves

Sympathetic division

functions as an emergency or catabolic system involved in fight or
flight responses, sympathetic axons are widely distributed throughout
the body

Pre-ganglionic neuron axon

attaches to the synapse of the post ganglionic neuron

Where are the preganglionic sympathetic neuron cell bodies found?

In the thoracic and upper lumbar segments of the spinal cord from T1
through L2 levels exclusively.

Sympathetics from T1-T5 innervate

The heart and lungs

What is the function of the parasympathetic division?

Conserve energy and restore body resources, only going to visceral
structures and not to the body walls.

The distribution of parasypathetic axons is


Where are the cell bodies of preganglionic parasympathetic neurons situated?

in the brainstem and exit the brain in 4 cranial nerves or at the
sacral spinal cord segments S2, S3, and S4

Vagus nerves

innervate the heart an lungs

Sympathetics to the heart

accelerate and strengthen heartbeat

Parasympathetics slow the heartbeat and

reduce cardiac output

Sympathetics to lungs

relax smooth muscle and dilate airways

Parasympathetics to lungs

constrict smooth muscle and close the airways

Symp nerves carry

visceral pain sensations back to the brain

Pain fiber courses back to

cord with sympathetics to heart (T1-4). Neurons in the cord are
"confused" as to the source of the pain.

Where is pain referred to?

T1-4 dermatomes; dull aching, poorly localized


bounded superiorly by the superior thoracic aperture, inferiorly by
the diaphragm

What is the anterior part of the thorax formed by?

Ribs and sternum

12 thoracic vertebrae articulate posteriorly with the


Composition of sternum

manubrium, body, xiphoid

Composition of ribs

7 true, 3 false, 2 floating

Sternal angle

key anatomic landmark between manubrium and body. Passes through
disks T4&5

Costal margin

below costal cartilages

__________ intercostal muscles run up and down while __________
intercostal muscles run diagonally

external; internal

External intercostal membrane

made up of dense connective tissue and covers the anterior of
internal intercostal muscle. It lines the deepest layer of chest wall

Where are the innermost intercostal muscles located?

under the internal intercostal muscle

Supplying all intercostal muscles are

intercostal nerves, veins, and arteries

To protect the neurovasculature from injury

a chest tube typically will be inserted into the interior portion of
the interspace so as not to injure the intercostal nerve, vein, and
artery at the top

Posterior intercostal arteries

supply oxygenated blood along the intercostal space up until it gets
to an anterior point where internal thoracic arteries supply the
anterior part of the intercostal muscles. These anterior arteries come
from anterior perforating intercostal vessels.

Posterior and anterior (smaller source of blood) muscles meet in the
middle called

collateral circulation

Human body has the ability to increase blood supply through the
___________________ if the ___________________ experiences blockage
and perfuse area of tissue that is deprived of blood

anterior artery; posterior artery

The deepest tissue lining the chest wall is

a friction reducing membrane