Axial pattern flaps

Question 1

random pattern flaps blood supply is based on the less robust subdermal plexus

Answer 1

T

Question 2

Random pattern flaps survive as long as the perfusion pressure of the feeding vessels maintains blood flow through the arterioles of the dermal plexus.

Answer 2

T

Question 3

As the distance from the flap pedicle increases, perfusion pressure dissipates; and when the arterioles close, necrosis ensues.

Answer 3

T

Question 4

The limits of perfusion pressure restrict the length of random pattern flaps.

Answer 4

T

Question 5

A terminal branch of the ophthalmic artery from the internal carotid arterial system, the STA (supratrochlear artery) exits the orbit by piercing the orbital septum at the superomedial orbital rim within 5 mm lateral or medial to a vertical line drawn at the medial canthus

Answer 5

T

Question 6

The supratrochlear pulse can be palpated at its exit point, which is a mean distance of 12.2 mm (range: 10.2–14.5 mm) superior to the medial canthus.

Answer 6

T

Question 7

The supratrochlear artery has a mean diameter of 0.9 mm.

Answer 7

T

Question 8

After emerging from the septum, the supratrochlear artery travels superficial to the periosteum and corrugator supercilii muscle and deep to the orbicularis oculi and frontalis muscles.

Answer 8

T

Question 9

The supratrochlear artery pierces the orbicularis oculi and frontalis muscles to reach the subcutaneous fat anywhere from 10–25 mm superior to the supraorbital rim.

Answer 9

T

Question 10

On the lower forehead, the supratrochlear artery and its branches travel in the deep subcutaneous fat closer to the frontalis muscle, usually on a path within 5 mm of a vertical line drawn at the medial canthus.

Answer 10

T

The STA can be absent or can rarely pass from superficial to deep to the frontalis muscle at the level of the mid-forehead, anatomic variations that risk necrosis of an aggressively thinned forehead flap. Tracing the path of the STA preoperatively with a Doppler probe identifies these rare anatomic variations and allows modification of flap design

Question 11

On the su­­perior third of the forehead, the supratrochlear artery runs nearer to the dermis as it courses cranially past the junction of the sagittal and coronal sutures at the top of the skull.

Answer 11

T

Question 12

Along its course, the STA (supratrochlear) has branches that communicate with numerous vessels, including the angular, supraorbital, paracentral, and central arteries.

Answer 12

T

Question 13

The most prominent glabellar frown line corresponds to the junction of the medial corrugator and procerus muscles, and can be accentuated by pushing the medial brows inferomedially toward the midline. The supratrochlear artery is located anywhere from this glabellar frown line to 6 mm laterally

Question 14

The supratrochlear artery pedicle can also reliably be found within 3 mm medial or lateral to the medial canthus. The pedicle base should therefore be wide enough to include these landmarks

Question 15

Mapping the artery via topographic landmarks can fail to detect rare anatomic variations that could threaten flap survival.

Question 16

While the STA provides the primary blood supply to the paramedian forehead flap, detailed anatomic studies demonstrate additional contributions from branches of the angular artery, the dorsal nasal artery, and the central and paracentral arteries.

Question 17

A branch of the external carotid system, the angular artery courses along the nasofacial sulcus and can be found on the fascia approximately 5 mm medial to a vertical line drawn at the medial canthus.

Question 18

The anuglar artery has a mean diameter of 1.0 mm. 4 Laterally, it has a communicating branch with the STA

Answer 18

T

A paracentral artery may arise either from the communicating branch or as a direct continuation of the angular artery toward the forehead.

Question 19

Medially, the angular artery anastomoses with the dorsal nasal artery, usually 5 mm above a horizontal line drawn at the medial canthus

Question 20

Like the STA, the dorsal nasal artery is another terminal branch of the ophthalmic artery, and it supplies blood to both the nasal tip and forehead.

Question 21

The dorsal nasal artery emerges from the orbital septum immediately inferiorly to the STA, at a mean distance of 7.1 mm (range: 6.4–7.5 mm) superior to the medial canthus.

Question 22

The dorsal nasal artery has a mean diameter of 0.82 mm

Question 23

The dorsal nasal artery anastomoses with the contralateral dorsal nasal artery and the ipsilateral angular artery.

Question 24

The dorsal nasal artery branches into the central artery, which runs superiorly toward the glabella and central forehead.

Answer 24

T
The central artery anastomoses medially with its contralateral counterpart and laterally with the STA

Question 25

The paracentral and central arteries may supply axial flow to a midline forehead flap.

Answer 25

T

Question 26

The mid-forehead and glabellar regions have two main venous drainage systems. The large ascending cutaneous vein, which is the most robust source of venous drainage, branches from the angular or transverse nasal root vein, pierces the procerus muscle, then runs cranially just beneath the dermis of the forehead skin.

Answer 26

T The course of the large ascending cutan­eous vein usually does not accompany the STA

Question 27

A minute reticular venous network surrounds the adventitia of the STA and provides a supplemental source of venous drainage

Answer 27

T While some authors recommend including the large ascending cutaneous vein in the flap pedicle to avoid venous congestion, our experience indicates that careful preservation of the venous network at the base of the flap pedicle is sufficient to avoid venous congestion.

Question 28

A cross-forehead donor site may violate the venous anatomy of the forehead. Venous congestion, as noted in this flap, often resolves spontaneously. Serial needling may be attempted for more rapid resolution.

Answer 28

T

Question 29

The paramedian forehead flap has sufficient length and blood supply to repair nasal defects at nearly any location. Distal nasal defects lie further from the donor site and require a longer pedicle, potentially requiring extension of the flap into the hair-bearing scalp.

Answer 29

T

Question 30

With respect to the paramedial forehead flap: Distal defects are also more likely to require cartilage grafts for support, especially on the alar lobule where non-anatomic cartilage helps to preserve the position of the free margin and to maintain airway patency.

Answer 30

T

Question 31

With respect to the paramedial forehead flap: Proximal defects of the nasal root, dorsum, and sidewall less commonly threaten airway function, since the septum and upper lateral cartilages gain support from their bony attachments, and the height of the forehead is usually sufficient to avoid extension of the flap into the hair of the scalp.

Answer 31

T

Question 32

In general, soft tissue loss on the tip, dorsum, and sidewall without damage to cartilage poses little risk for airway compromise.

Question 33

By contrast, defects involving the ala frequently require non-anatomic cartilage grafting to support the airway and position of the free margin

Question 34

What layers need to be repaired for this defect?

Answer 34

Loss of cartilage increases the complexity of reconstruction, since free cartilage grafting may be necessary to restore nasal contour and projection and to stabilize the airway. Full-thickness nasal defects present the greatest challenge, as they require repair of mucosal lining, cartilage, and skin. Such defects are most common on the ala and soft triangle and may require a three-stage, rather than a two-stage, forehead flap.

Question 35

At the alar lobule, there are five distinct nasal soft tissue layers: the skin, subcutaneous fat, superficial musculoaponeurotic system (SMAS), deep areolar layer, and perichondrial or periosteal layer.

Answer 35

T