Head and Neck



Head and Neck






PAROTID GLAND AND FACIAL NERVE (PAROTIDECTOMY)


INCISION

Perform an S-shaped preauricular incision extending from the top of the external ear to the midneck (Fig. 1.1).



CLINICAL HIGHLIGHTS



  • Conceptualize facial nerve location by the following process as suggested by Beahrs. Place your fingertip on the mastoid process pointing forward. A dime-sized area deep and anterior to the fingertip will have the nerve within it (Fig. 1.5B). This method uses the tympanomastoid suture as a landmark. This line is found between the posterior bony auditory canal and the mastoid portion of the temporal bone. The facial nerve is located 6 mm deep.


  • The marginal mandibular branch of the facial nerve (VII) will be preserved above a transverse cervical incision made three fingerbreadths (4 cm) below the mandible. This nerve and the anterior ramus of the cervical branch supply innervation to the muscles of the corner of the mouth of the lower lip. Injury will result in persistent severe facial expressive disorder (Fig. 1.7A).


  • If the anterior ramus of the cervical branch is injured, minimal drooling will resolve after 4-6 months.


  • To Zanzibar By MotorCar: facial nerve branches. Temporal, Zygomatic, Buccal, Marginal Mandibular, Cervical. Or place your palm over your parotid and each digit will point to one branch (Fig. 1.5A).


  • Frey syndrome is “gustatory sweating” of the ipsilateral face after division of the auriculotemporal nerve in the distribution of the sympathetic denervation.







Figure 1.7 A: “Neural hammock” of the marginal mandibular branch (A) and anterior ramus of the cervical branch (B). B: Structures exposed after submandibular gland excision.


SUBMANDIBULAR GLAND (SUBMANDIBULAR GLAND EXCISION)


INCISION

For purposes of exposure and demonstration, the typical transverse incision performed in the OR is not used in the anatomy lab. Instead, continue the skin incision on the anterior border of the sternocleidomastoid to the suprasternal notch bilaterally. If you have used each side for the previous dissection, an anterior cervical flap will now be developed. Divide the skin from the tip of the chin in the midline down to the suprasternal notch. Each flap can now be elevated sharply deep to the platysma. This will expose the submandibular gland above the anterior and posterior bellies of the digastric muscle. In the operating room, exposure of the submandibular gland would be through an incision 4 cm below and parallel to the mandible extending deep to the platysma to preserve the marginal mandibular nerve. Skandalakis uses the term “neural hammock” to describe the innervation of the muscles of the lower lip. Neural hammock of the marginal mandibular branch (A) and anterior ramus of the cervical branch (B) are shown (Fig. 1.7A).







Figure 1.8 Submandibular gland located above the sling of the digastric muscle.



CLINICAL HIGHLIGHTS



  • Note that the lingual nerve may encircle the submandibular duct during its course. Injury to the lingual nerve, a branch of the trigeminal nerve V3, VII, and IX, will cause loss of taste of the anterior two-thirds of the tongue.


  • Injury to the hypoglossal nerve will cause deviation of the tongue toward the injured side when the patient sticks the tongue out. The hypoglossal nerve (XII) is motor supply to the lateral tongue.


  • The mandibular notch is a dependable landmark to find the marginal mandibular branch of the facial nerve.


  • Injury to the neural hammock nerves will cause drooling involving the marginal mandibular nerve, which does not resolve, or minimal drooling involving the anterior ramus of the cervical branch resolving in 6 months.






Figure 1.10 Introducer needle position for percutaneous cricothyroidotomy.


EMERGENCY AND PERMANENT SURGICAL AIRWAYS (CRICOTHYROTOMY, TRACHEOSTOMY)


EMERGENCY CRICOTHYROTOMY


Incision

Percutaneous: A Blue Rhino or Ruesch percutaneous set will only require a small longitudinal incision at the level of the cricothyroid membrane.

Open: Open cricothyrotomy will need a 3-cm longitudinal incision above and below the level of the cricothyroid membrane. In a live patient, little bleeding will occur due to the longitudinal orientation of the neck vessels and strap muscles in the area.



ELECTIVE TRACHEOSTOMY


Incision

Palpate anatomic landmarks, which include the thyroid notch, the cricoid cartilage, and the sternal notch. If no incisions have been done, perform a wide transverse “collar” incision 2 finger breadths above the sternal notch, or at the inferior border of the cricoid cartilage. The incision must be wide enough on the body to fully expose the underlying anatomy.



Clinical Highlights



  • The worst error with any of the techniques is a misplaced tube. Most commonly the tube can be misplaced in the soft tissue of the neck between the trachea and sternum. Perforation of the posterior tracheal membrane and esophageal damage or intubation can occur. Submembranous placement of the tube can occur if it is placed between the tracheal cartilage and tracheal mucosa. Having the tube in place but inadequately secured in an emergent situation may lead to a dislodged tube.






    Figure 1.13 Excision of anterior segment of the third tracheal ring for tracheostomy.







    Figure 1.14 Position of thyroid, parathyroids, and trachea.


  • Be sure to monitor O2 saturation and/or exhaled CO2 to ensure ventilation.


  • For orientation, see Figure 1.14 to see position of thyroid and parathyroid glands.


THYROID AND PARATHYROIDS (THYROIDECTOMY, PARATHYROIDECTOMY)


INCISION

The incision must be wide enough on the body to fully expose the underlying anatomy. Use the previous incisions (Fig. 1.15), which are not the “collar” incision used in the OR. Create subplatysma flaps superiorly to the thyroid cartilage and inferiorly to the sternal notch. In the OR, you will see vertical separation of the strap muscles (see Fig. 1.12). However, for purposes of exposure in the lab, divide the strap muscles transversely across the upper third of their length (Fig. 1.16). Retraction of the strap muscles laterally gives adequate exposure in the operating room, but rarely, these muscles need to be divided when a very large tumor or goiter is encountered. Remember that the innervation to the strap muscles comes in posteriorly in the lower twothirds of the muscle from ansa cervicalis branch of cervical branch of the facial nerve (see Fig. 1.6).






Figure 1.15 Incisions for head and neck exposure in the anatomy lab.

Oct 15, 2018 | Posted by in ANATOMY | Comments Off on Head and Neck
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