Parotidectomy

• Extent of the parotidectomy depends on the underlying pathology necessitating surgery
• Important to balance adequate surgical excision with preservation of form and function
• Classification of parotidectomy techniques:
  1. Non-nerve dissecting
     1. Extracapsular dissection
  2. Nerve dissecting
     1. Partial superficial parotidectomy
     2. Superficial parotidectomy
     3. Total parotidectomy with preservation of the facial nerve
     4. Radical parotidectomy

Surgical Anatomy

Parotid Gland

• The parotid glands are situated in a pre-auricular and retromandibular location
• They overlie the mandibular rami and masseter muscles
• They extend behind the masseter muscles into the retromandibular fossa
• Superiorly the glands extend to the zygomatic arches
• Inferiorly they cross the angle of the mandible and overlie the posterior bellies of the digastric and the sterenocleidomastoid muscles
• Parotid duct exits the gland anteriorly → crosses the master muscle then turns medially on the muscles anterior margin → pierces the buccinator muscle and enters the oral vestibule adjacent to the upper second molar tooth

Superficial Musculo-Aponeurotic System and Parotid Fascia

• The Superficial Musculo-Aponeurotic System (SMAS) is a fibrous network that invests the facial muscles and connects them with the dermis
  • It is continuous with the platysma inferiorly; superiorly it attaches to the zygomatic arch
  • In the lower face, the facial nerve courses deep to the SMAS and the platysma
• The parotid glands are contained within two layers of parotid fascia
  • Parotid fascia is a continuation of the superficial layer of the deep cervical fascia
  • This then splits into two layers to contain the parotid gland
  • The superficial layer is fixed to the zygomatic arch superiorly where it joins the temporal fascia
  • The deep layer is extends to the base of skull and is thickened between the styloid process and angle of mandible, forming the stylomandibular ligament

Adjacent Structures

Anatomical Relationships

Posterior	Cartilage of external auditory meatus Tympanic bone Mastoid process Sternocleidomastoid muscle
Deep	Styloid process Stylomandibular tunnel Parapharyngeal space Posterior belly of digastric Sternocleidomastoid muscle
Superior	Zygomatic Arch Temporomandibular Joint

Structures that pass through the parotid

Facial Nerve
External Carotid Artery (ECA)	The ECA ascends through the parotid gland. Within the gland, the ECA gives rise to the posterior auricular artery before dividing into its two terminal branches – the maxillary artery and superficial temporal artery The transverse facial artery also comes off the superficial temporal before it leaves the gland. Running forward through the substance of the gland, it passes transversely across the side of the face, between the parotid duct and the lower border of the zygomatic arch, and divides into numerous branches, which supply the parotid gland and parotid duct, the masseter muscle, and the integument, and anastomose with the facial artery, the masseteric artery, the buccinator artery, and the infraorbital artery.
Veins	The maxillary and superficial temporal veins merge into the retro-mandibular vein within the parotid gland but are not responsible for draining the gland. Venous drainage of the parotid itself is to tributaries of external and internal jugular veins.
Lymphatic	A number of lymph nodes are present within the gland, principal-ly in the superficial lobe, and drain to Level 2 of the neck