Management Of The Sternocleidomastoid Muscle

Including the posterior triangle of the neck in the field of dissection requires a combined approach, both posterior and anterior to the sternocleidomastoid muscle (Fig. 4-15). In the upper half of the neck the dissection is performed anterior to the sternocleidomastoid muscle, whereas in the lower half of the neck the supraclavicular fossa is approached posterior to the sternocleidomastoid muscle.

To better understand this, imagine the surgical field divided horizontally in two halves by a line passing through Erb's point, the place where the superficial branches of the cervical plexus appear at the posterior border of the sternocleidomastoid muscle. This creates an upper and a lower part of the neck.

The upper half of this division includes the submental and submandibular nodes (area I), the upper part of the posterior triangle of the neck (upper part of area V), and part of the lymphatic chain of the internal jugular vein (area II and part of area III). The dissection of the upper half of this division is performed anterior to the sternocleidomastoid muscle. For this purpose, the muscle must be retracted posteriorly throughout the dissection.

The lower half of this imaginary division includes the supraclavicular fossa (lower part of area V), the lower part of the lymphatic chain of the internal jugular vein (area IV and part of area III), and the paratracheal lymph nodes (area VI). These regions will be approached both posterior and anterior to the sternocleidomastoid muscle. The supraclavicular fossa will be dissected from behind the muscle, and the remaining lymph structures of the lower half of the neck will be approached anterior to the sternocleidomastoid muscle.

For the surgical specimen to be removed en bloc, the tissue removed from the supraclavicular fossa will be passed beneath the sternocleidomastoid muscle to meet the remaining part of the specimen. This maneuver, which has always been difficult to understand, is detailed in the following text.

V

i. <

/s'S ,1$

f k^^ym <

Sit1 ->,\ v 1

V; ;. \ ' fe h Î." J- J v '■ \ " q

* SC

TM

s \\ '•. j v i v .

Figure 4-15 Schematic view of the approach to the neck for a complete functional neck dissection. Above Erb's point the operation is performed anterior to the sternocleidomastoid muscle. The lower part of the posterior triangle (supraclavicular fossa) is approached posterior to the sternocleidomastoid muscle. SC, sternocleidomastoid muscle; TM, trapezius muscle; Erb's point.

Figure 4-16 Anatomical landmarks for the identification of the spinal accessory nerve on its course between the internal jugular vein and the sternocleidomastoid muscle (right side). transverse process of the atlas; sa, spinal accessory nerve; IJ, internal jugular vein; dg, digastric muscle; sl, splenius cervicis and levator scapulae muscles; sc, sternocleidomastoid muscle.

Figure 4-15 Schematic view of the approach to the neck for a complete functional neck dissection. Above Erb's point the operation is performed anterior to the sternocleidomastoid muscle. The lower part of the posterior triangle (supraclavicular fossa) is approached posterior to the sternocleidomastoid muscle. SC, sternocleidomastoid muscle; TM, trapezius muscle; Erb's point.

Now we shall resume the dissection at the point where we left it. The sternocleidomastoid muscle was almost completely free of its fascia, except for a small part at the posterior edge of the muscle, and the attention of the surgeon was directed to the upper part of the surgical field to identify the spinal accessory nerve on its course between the jugular foramen and the sternoclei-domastoid muscle.

0 0

Post a comment