SURGERY Maryof Sutton, the CST, CFAHead and Neck his article is one of a tumor to allow the patient to get series that will discuss nourishment or a proper route T head and neck surger- of respiration. ies from an otolaryngology per- Surgeons in other specialties spective. Most of these surger- may assist the otolaryngologist ies involve cancer, and often with these procedures, such as involve portions of the alimen- a total laryngopharyngectomy tary or respiratory tracts that with a gastric pull-up or repair must not be compromised. The of a defect with a pedicle or free desired outcome is excision of fl ap, such as a mandibulectomy the tumor, which may present with a fi bular free fl ap. some cosmetic problems for the Part one examines the anato- patient. If excision is not feasi- my of the head and neck, vari- ble, then any palliative proce- ous types of dissection and the dure may include bypassing the related instrumentation. JUNE 2005 The Surgical Technologist 9 257 JUNE 2005 2 CE CREDITS IN CATEGORY 1 Neck anatomy Innervation The neck contains major communication Severa l major ner vous structures course routes from the head to the rest of the body. It throughout the neck. Knowledge of the course holds the spinal cord, the air and food passages, of these nerves is important in any dissection of major nerve pathways that include several cra- the neck or neck structures. The marginal man- nial nerves and their branches, and the major dibular branch of the facial nerve (VIIth cranial) blood vessels that flow between the head and the dips below the mandible into the fascia above the heart. submandibular gland, before ascending upward to innervate the corner of the mouth. The cervi- Musculature cal branch of the facial nerve innervates the pla- The strap muscles of the neck connect the lar- tysma, the stylohyoid muscle, and the posterior ynx and associated structures, such as the hyoid belly of the digastric. bone, with the sternum anteriorly. There are The vagus nerve travels inferior to the carotid also muscles that connect the hyoid bone with within the carotid sheath. In the chest, the vagus the base of the tongue, mandible, and the styloid sends a branch back to the larynx. This branch, process of the temporal bone. the recurrent laryngeal nerve, ascends along the The strap muscles of the neck connect the tracheoesophageal (TE) groove and enters the larynx and associated structures, such as the larynx to innervate the true vocal cords. Great hyoid bone, with the sternum anteriorly. There care is taken to identify and preserve this nerve are also muscles that connect the hyoid bone in head and neck surgeries, especially thyroid- with the base of tongue, mandible, and the sty- ectomy and parathyroidectomy, as damage to loid process of the temporal bone. The digas- this nerve will cause vocal cord paralysis with its tric muscle has one belly, which extends from associated pathology. the mastoid to the hyoid and then ascends to The spinal accessory nerve (XIth crani- the anterior mandible about at the midline. The al) travels from the skull base to innervate the sternocleidomastoid muscle divides the neck SCM and the trapezius muscle, usually above the into anterior and posterior triangles. The pos- level of the carotid bifurcation below the digas- terior triangle is mostly the musculature of tric muscle. The hypoglossal nerve (XIIth crani- the spinal cord; whereas, the anterior triangle al) travels from the skull base to cross the carot- is composed of most of the major vessels and id artery, usually above the bifurcation, and then structures of the neck. The anterior neck may ascends to innervate the tongue. Often dur- be divided into smaller triangles for dissection ing neck dissections, there are two areas where purposes. knowledge of the course of the hypoglossal The anterior and posterior bellies of the nerve is important—the carotid bifurcation and digastric muscle form the submandibular tri- the area where the nerve ascends through tis- angle. Both anterior bellies of the digastrics sue inferior to the submandibular gland. When form the submental triangle, which is the mid- performing a laryngectomy, care is taken not to line of the neck. The vascular or carotid trian- injure the hypoglossal nerve, as it passes close to gle is inferior to the digastric and hyoid. The the lateral horn of the hyoid bone. omohyoid muscle, which is important in dis- The lingual nerve is identified in subman- section landmarks, runs from the hyoid to the dibular gland excision as it travels superior and scapula, almost perpendicular to the sterno- deep to the gland. The phrenic nerve travels in cleidomastoid muscle (SCM). The platysma the posterior neck to the diaphragm from cer- muscle extends from the clavicle to the acromi- vical roots 3-5. The brachial plexus also starts in on process of the scapula, the deltoid fascia, and the posterior neck, running from C5 to T1. There the pectoralis major to the lower border of the is also a cervical sympathetic chain, which trav- mandible. els in the carotid sheath. 10 The Surgical Technologist JUNE 2005 Tumor stagi ng ( TNM ) Vascularity The major artery to the head is the carotid, which In head and neck cancer, as well with other cancers, there branches in the neck to the external and inter- is a tumor staging system that identifies the size of the nal carotid arteries. The internal carotid has no tumor, lymph node involvement, and metastasis. The branches in the neck. The branches of the exter- tumor is identified in three ways: a “T” class, which repre- nal carotid artery in the neck include: the supe- sents the size and depth of the tumor; an “N” class, which rior thyroid, ascending pharyngeal, facial, lin- represents the site of nodal metastasis, if any, the number gual, occipital, postauricular, and the internal of nodes involved, and the size of these nodes; and an “M” maxillary arteries. class, which represents metastasis to distant tissues. The carotid artery courses through the neck within its own carotid sheath. Also contained The “T” class is as follows: within the sheath are the vagus nerve and the T0 Unknown primary tumor internal jugular vein. The external jugular vein T1 0 cm to 2 cm is more lateral in the neck. There are also anteri- T2 2 cm to 4 cm or jugular veins, which run along the midline of T3 4 cm to 6 cm the neck along the strap muscles. T4 Greater than 6 cm Tx Primary tumor cannot be assessed Pharynx, larynx, esophagus, and trachea The pharynx, larynx, esophagus, and trachea The “N” class is as follows: also are major structures of the neck. The phar- N0 No lymph node metastasis ynx and larynx are closely associated in the N1 Single lymph node, less than 3 cm on the same side as anatomy of the neck until they separate, approx- the tumor imately at the level of the cricoid cartilage, to N2a Single lymph node, 3-6 cm on the same side as the become the esophagus and trachea. tumor The thyroid gland resides anterior and later- N2b Multiple nodes, none greater than 6 cm, same side al to the trachea, below the strap muscles. Blood N2c Bilateral or opposite nodes, none greater than 6 cm supply to the thyroid is from both superior and N3 Metastasis in a node greater than 6 cm inferior poles, but care is taken to identify the NX Nodes cannot be assessed (usually due to a node recurrent laryngeal nerve before sacrificing any biopsy) structures around the thyroid. Paired parathy- roid glands are usually found on the posterior The “M” class is as follows: aspect of the thyroid gland, but may be found as M0 No distant metastasis (cancer has not spread to dis- inferiorly as the mediastinum. tant body structures) M1 Distant metastasis (cancer has spread to distant body Lymphatics structures) Cervical lymph nodes are divided into sever- MX Distant metastasis cannot be assessed al levels for dissection. These levels are deter- mined by the anatomic structures of the tissue Tumor staging is usually done from the patient’s CT scan, in which they reside. The importance of levels but the surgeon may perform whatever appropriate sur- for neck dissections is due to the recent studies gical procedure is needed to view the primary tumor. The of the lymphatic metastasis from different head surgeon will also palpate the neck to feel for enlarged and neck tumors. It has been found that, based lymph nodes. When staging laryngeal tumors, since the on the location of the tumor, there is a specif- vocal cord isn’t 6 cm or greater, the tumor would be staged ic lymphatic flow and, therefore, a greater pro- according to the surface area of the vocal cord consumed pensity for the lymph nodes in that flow zone to by tumor, whether it crosses over the midline and how far become metastatic. onto the opposite cord. JUNE 2005 The Surgical Technologist 11 Mandible Mylohyoid (cut and reflected) Mylohyoid Geniohyoid Stylohyoid Anterior belly Digastric { Posterior belly Hyoid bone Thyrohyoid Sternocleidomastoid (cut) Cartilages of larynx Cricothyroid Superior belly Omohyoid { Inferior belly Sternothyroid Sternocleido- Clavicular head mastoid { Sternal head Clavicle Sternum Cut heads of sternocleidomastoid Sternohyoid Level I lymph nodes are the nodes within the Level III lymph nodes are the middle jugular submental triangle (level Ia), and those found nodes. These lymph nodes reside in the middle within the submandibular triangle (level Ib). third of the jugular vein from the carotid bifur- Obviously, since the submental triangle is mid- cation superiorly to the junction of the omo- line, there would be only one specimen for level hyoid muscle, with the jugular vein inferior- Ib for both sides of the neck (eg if performing a ly.