Welcome to this
presentation on skin innervation.
My name is Martin Schmelz.
I'm a neurophysiologist, and having
worked mainly on pain and itch.
In this presentation,
we will first focus
on structure and sensory
function in healthy skin
and then switch to skin innervation
changes that happen in disease,
such as loss of innervation
and increased innervation that may
be found in chronic itch and pain.
And finally, we will also
touch upon neuronal function
beyond sensory tasks.
When we regard innervation
of healthy skin,
the most abundant nerve fibers are
small nerve fibers with free nerve
endings that innervate
the dermis, and are
particularly dense in the epidermis.
In contrast, these
thick nerve fibers
have specific sensory endings
such as the Pacinian corpuscles
and the Meissner corpuscles,
located in the dermis.
The myelinated fibers are low
threshold mechanosensitive fibers
that are important to
detect touch and texture.
They can be differentiated into
superficial and deeply located
ones, with the superficial
ones having small innervation
territories and deep ones,
large innervation territories.
Merkel and Ruffini endings are
slowly adapting, meaning that they
encode chronic stimuli, whereas
Meissner receptors and Pacinian
corpuscles are rapidly
adapting, such that they
are particularly sensitive
to phasic simulation.