Blood Supply of the Skin

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Blood Supply of the Skin

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Anatomy of Circulation

• The blood reaching the skin originates from deep
  vessels
• These then feed interconnecting perforator
  vessels which supply the vascular plexus
• Thus skin fundamentally perfused by
  musculocutaneous or septocutaneous perforators

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Nahai-Mathes Classification
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Anatomy of Circulation

• The vascular plexuses of the fascia, subcutaneous
  tissue and skin are divided into 6 layers

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Anatomy of Circulation

• 1)Subfascial plexus
• small plexus lying on the undersurface of the
  fascia

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Anatomy of Circulation

• 2) Prefascial plexus
• -a larger plexus
• -particularly prominent on the limbs
• -fasciocutaneous vessels

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Anatomy of Circulation

• 3)Subcutaneous Plexus
• -lies at the level of superficial fascia
• -Predominant on the torso
• -musculocutaneous vessels

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Anatomy of Circulation

• 4)Subdermal Plexus
• -receives blood from underlying plexus
• -the main plexus supplying blood to the skin
• -represents the dermal bleed observed in incised
  skin

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Anatomy of Circulation

• 5) Dermal Plexus
• -mainly arterioles
• -important in thermoregulation

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Anatomy of Circulation

• 6)Subepidermal Plexus
• -contains small vessels without muscle in the
  walls
• -nutritive and thermoregulatory function

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Angiosomes

• Similar to a skin dermatome is a composite block
  of 3 dimensional tissue supplied by a named
  artery
• Entire skin surface of the body is therefore
  perfused by a multitude of angiosome units
• First studied by Marchot 1889, expanded by Salmon
  1930 and more recently by Ian Taylor

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Angiosomes

• Each angiosome is linked to its neighbour at
  every tissue level, either by
• a true (simple) anastomotic arterial connection
  without change in caliber of the vessel
• or by a reduced-caliber choke anastomosis.

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Taylor GI, Palmer JH. The vascular territories
(angiosomes) of the body experimental study and
clinical applications. Br J Plast Surg.
198740113.

• The sites of emergence of the direct and indirect
  cutaneous arterial perforators of 0.5 mm or
  greater averaged from all studies.
• Direct perforators are more common in the limbs,
  whereas indirect perforators predominate in the
  torso

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Choke vessels. A Schematic of choke anastomoses
(A) and true anastomoses (B) between adjacent
arteries. (Taylor GI, Minabe T. The angiosomes of
the mammals and other vertebrates. Plast Reconstr
Surg. 199289181.
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Choke Vessels

• Choke vessels play an important role in skin-flap
  survival, they provide an initial resistance to
  blood flow between the base and the tip of the
  flap.
• When a skin flap is delayed by the strategic
  division of cutaneous perforators along its
  length, these choke vessels dilate to the
  dimensions of true anastomoses thus enhancing the
  circulation to the distal flap

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Delay Phenomenon

• Is a preliminary surgical intervention wherein a
  portion of the vascular supply to a flap is
  divided before definitive elevation and transfer
  of the flap
• Mechanism of this phenomenon is controversial

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Delay Phenomenon

• Increased axiality of blood flow
• Removal of blood flow from periphery of a random
  flap promotes development of axial flow
• Tolerance to ischaemia
• Cells become accustomed to hypoxia
• Sympathectomy vasodilation theory
• Thus leading to vasodilation
• Dilation of choke vessels
• Hyperadrenergic theory

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The angiosome concept has important clinical
implications

1. Each angiosome defines the safe anatomic boundary
   of tissue in each layer that can be transferred
   separately or combined on the underlying source
   vessels as a composite flap.
2. Because the junctional zone between adjacent
   angiosomes usually occurs within muscles of the
   deep tissue, rather than between them, these
   muscles provide an important anastomotic detour
   (bypass shunt) if the main source artery or vein
   is obstructed.

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The angiosome concept has important clinical
implications

• 3) Because most muscles span two or more
  angiosomes and are supplied from each territory,
  one is able to capture the skin island from one
  angiosome by muscle supplied in the adjacent
  territory.