Relevant anatomy

Authors: Ahmad Makki MD, Magnus Balslev Avnstorp MD, Thomas Givskov Sørensen and Chrisitan Kaare Paaskesen Med. Stud.

Anatomical parts of the flap

The following should be considered when performing microsurgery. What tissue is to be harvested: Skin / fat / fascia / muscle flap. The nerve innervation of the area: In free flaps the sensory and motor nerves are cut, but in some cases of pedicled flaps the nerves may be spared. The Arterial blood supply: Perforators range from 0.3 mm, over 1 mm. to 4 mm. in diameter depending on the flap and type of blood supply. Veins are typically one or paired veins and are essential for adequate drainage of the flap.

Pedicle length on flap is also important. In some cases the pedicle may be long ex. in DIEP flaps, and short in other cases of ex. TMG flaps. It’s also important to be aware of the recipient vessels: In cases of the DIEP flap the Internal thoracic vessels

Classification of muscle and myocutaneous flaps based on pattern of circulation (As of Mathes and Nahai):

• Type I: One vascular pedicle – e.g. Tensor Fascia Latae muscle
• Type II: Dominant pedicle(s) and minor pedicle(s) – e.g. Gracilis muscle
• Type III: Two dominant pedicles – e.g. Gluteus Maximus muscle
• Type IV: Segmental vascular pedicle – e.g. Sartorius muscle
• Type V: One dominant pedicle and secondary segmental pedicle – e.g. Latisimus dorsi muscle

Types of microsurgical flaps

Reconstruction could be performed using different types of flaps, dependent on the tissue type and size needed and the vascular supply.

• Free flap e.g. Inferior Gluteal Artery Perforator (IGAP) flap or DIEP.

• Composite tissue transfers e.g. Anterior Lateral Thigh (ALT) flap or Latissimus Dorsi flap which both are musculo-cutaneous flaps.

• Functional free muscle transfers e.g. gracilis muscle flap for upper extremity reconstruction for elbow flexion.
• Vascularized bone grafts e.g. vascularized free fibula flap for mandible reconstruction.

Acknowledgments

Illustrations: Marie Nolsøe Helles Med. Stud. Caroline Lilja Med. Stud. and Emma Tubæk Med. Stud.