KEY NOTES CHAPTER 1: GENERAL PRINCIPLES - Blood supply to the skin. Flashcards
What is the onterconnecting system composed of?
- Fasciocutaneous (or septocutaneous) vessels
- directly traverse fascial septa, e.g. limbs. - Musculocutanous vessels
- indirectly to skin via multiple perforating muscular branches, e.g. torso.
How does blood reach the skin?
- Deep vessels supply
- Interconnecting vessels which supply
- Vascular plexuses of fascia, sc tissue and skin.
Name the vascular plexuses of fascia, subcut tissue and skin.
- Subfascial - under deep fascia
- Prefascial - superficial to deep fascia. Main supply = fc vessels, predominant in limbs.
- Subcutaneous - superficial fascia. Main supply mc vessels, predominant in torso.
- Subdermal - main plexus supplying skin.
- Dermal - mainly arterioles, important in thermoregulation.
- Subepidermal - nutrition and thermoregulation.
N.B. epidermis contains no blood vessels.
What is an angiosome?
A 3D composite block of tissue supplied by a named artery.
Who are the names associated with describing angiosomes?
Manchot 1889.
Salmon 1930.
Taylor and Palmer - coined angiosome.
What are the anatomical, dynamic and potential territories of an artery?
Anatomical - area of tissue supplied by an artery before anastomosing with adjacent vessels.
Dynamic - area of tissue into which fluorescein extends into after injection into artery. Blood flow is regulated by choke vessels linking adjoining angiosomes.
Potential - area of tissue that can be included if flap was delayed.
What are choke vessels?
Vessels that pass between anatomical territories.
What are the anatomic concepts of blood supply developed by Taylor and Palmer?
- Blood supply detours thru muscles
- Arteries link to form continuous unbroken network.
- Intramuscular territories of arteries and veins match.
- Vessels hitchhike with nerves.
- Vessels follow connective tissue framework.
- Vessels radiate from fixed to mobile areas.
- There is a direct relationship b/t muscle mobility and the size and density of the supplying vessels.
- Vessels tend to have a constant destination but a variable origin.
- Territory of the intramuscular arteries obeys law of equilibrium.
- Vessels size and orientation are the product of tissue differentiation in the area.
- Muscles are the prime movers of venous return.
- As arterial territories are linked by choke vessels, so the venous territories are linked by oscillating veins, which are devoid of valves.
Describe the different theories of the TRAM flap angiosomes.
Zone 1 - ipsilateral DIEA musculocutaneous perforators supplies the anatomical territory
Hartrampf 1982.
Zone 2 = contralateral to midline.
Holm 2006.
Zone 2 = lateral to zone 1 (anatomical territory of SCIA). Perfusion from DIEA crosses 1 set of choke vessels.
Zone 3 = contralateral to midline = dynamic territory.
Zone 4 - perfusion crosses 2 sets of choke vessels
How is blood flow controlled by the muscular tone of vessels?
- Myogenic theory
- pressure of blood within vessels (increased intraluminal pressure, vessels constrict). - Neural innervation
- sympathetic control of arterioles, AVAs and pre-capillary sphincters. (Cutaneous blood flow is reduced by increased tone of arterioles, decreased AVA tone and increased pre-capillary sphincter tone.) - Humoral factors
(- Epinephrine, norepinephrine, serotonin, TXA2, PG cause vasoconstriction.
- Histamine, bradykinin and PGE1 cause vasodilatation, as does low O2, high CO2 and acidosis). - Temperature - heat causes vasodilatation and increased flow through AVAs, bypassing capillaries.
What is the delay phenomenon?
Any preop manoeuvre that results in increased flap survival. 1. Increased axiality of blood flow. 2. Tolerance to ischaemia. 3. Sympathectomy vasodilatation theory. 4. Intraflap shunting hypothesis. 5. Hyperadrenergic state. Unifying theory (Pearl) - all 5.
