return to: Sialogram Technique; Bartholin's duct on normal sialogram; Bartholins duct anatomy; Salivary Ductoplasty
see also: Classification of Salivary Duct Stenosis (Parotid Duct Stricture - Submandibular Duct Stricture); Case example Submandibular Gland Resection; Salivary Stone Removal with Ductoplasty from Submandibular Gland; Plunging Ranula Transoral Resection (Sublingual Gland) Aided With Sialendoscopy with Histopathology

Diagram above according to Iowa Sialogram Classification System (Foggia 2020, Thorpe 2020)

Anatomy of the submandibular gland & duct and the submandibular triangle (Level 1b)

1. Characterized by an acinar-ductal system (as are all 3 major salivary glands)
   1. Saliva is produced within the acinus which is comprised of pyramidal cells grouped about a central lumen.
   2. Saliva is modified in character as it moves successively from the acini through intercalated ducts, striated ducts and excretory ducts and finally into the oral cavity
   3. The predominant cell type within the acinus of the submandibular gland is seromucous (in contrast to the parotid which is predominately serous and the sublingual gland in which mucous cells comprise the majority)
2. Submandibular triangle (level 1B)
   1. Borders: anterior and posterior bellies of the digastric muscle and the lower border of the mandibular body
   2. Contents: submandibular gland, lymph nodes, facial artery, facial vein (crosses the gland superficially)
      1. The submandibular gland overlies both bellies of the digastric muscle with the posterior border lying near the anterior-inferior aspect of the parotid gland at the mandibular angle
      2. The marginal mandibular branch of the facial nerve usually overlies the gland as it passes from the cervicofacial branch of the facial nerve to innervate the deep surface of the lower lip depressors lying in a plane deep to platysma and superficial to the submandibular gland fascia
      3. The upper aspect of the superficial surface of the gland lies partly against the submandibular depression on the inner surface of the mandibular body and partially on the mylohyoid muscle  
      4. The deep surface of the gland overlies:
         1. Mylohyoid muscle
         2. Hyoglossus muscle
         3. Styloglossus muscle
         4. Stylohyoid muscle
         5. Posterior belly of the digastric muscle
      5. The anterior aspect of the submandibular gland splits to surround the posterior aspect of the mylohyoid muscle with a deep extension bordered by the hyoglossus muscle and the styloglossus muscle medially and the mylohyoid muscle laterally
         1. Located superiorly to the deep process of the gland are:
            1. The submandibular ganglion
            2. The lingual nerve
      6. Located inferiorly to the deep process of the gland is the hypoglossal nerve
3. Submandibular (Wharton's) Duct
   1. Extends from the anterior aspect of the submandibular gland deep to mylohyoid on the lateral surfaces of the hyoglossus muscle and genioglossus muscle, which are lateral to the hypoglossal nerve
   2. As the duct exits the gland, it lies inferior to the lingual nerve
   3. As the duct continues distally, the lingual nerve passes below the duct and then crosses it medially, forming a near-complete loop around the duct (see photos at: Salivary Ductoplasty)
   4. The terminal aspect of the duct lies in contact with the sublingual gland as it lies in a submucosal plane within the floor of mouth

Ultrasound anatomy of submandibular gland (Katz, 2009) see: Salivary Ultrasound

• Location: anterior and caudal to the parotid gland.
• Other structures in the region: Bone - mandible; Muscles - mylohyoid, anterior belly of the digastric; Vessels - facial artery and vein. On oblique view of SMG, can see palatine tonsil.
• Echostructure: the submandibular gland is more hypoechoic than the parotid gland.
• Appearance: triangular shape with a posterior base. Rarely seen are normal intraglandular ducts. With stimulation (sialogogue), visualization may be easier.
  • Wharton's duct originates from the deep portion of the gland and ascends anteriorly to the floor of the mouth, differentiated from the lingual vessels by color Doppler.

References

Foggia MJ, Peterson J, Maley J, Policeni B, Hoffman HT. Sialographic analysis of parotid ductal abnormalities associated with Sjogren's syndrome. Oral Dis. 2020 Jul;26(5):912-919. doi: 10.1111/odi.13298. Epub 2020 Mar 3. PMID: 32031309.

Thorpe RK, Foggia MJ, Marcus KS, Policeni B, Maley JE, Hoffman HT. Sialographic Analysis of Radioiodine-Associated Chronic Sialadenitis. Laryngoscope. 2020 Nov 17. doi: 10.1002/lary.29279. Epub ahead of print. PMID: 33200832.

Hoffman H, Funk G, Endres G. Evaluation and surgical treatment of tumors of the salivary glands. In: Themley SE, Ponje WR, Botskis JG, Lindberg RD, eds. Comprehensive Management of Head and Neck Tumors. 2nd ed. Philadelphia, Pa: WB Saunders, 1999

Katz P, Hartl DM, Guerre A.  Clinical ultrasound of the salivary glands.  Oto Clin N Am. 2009; 42(6):973-1000