submandibular and sublingual glands - normal

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for normal anatomy and scanning protocol

the submandibular gland lies deep to the body of the mandible. it protrudes slightly inferiorly and superficially.

the submandibular duct (wharton’s duct) courses anteriorly to then rise into the floor of the mouth behind the lower incisors, lateral to the frenulum. between the buccal muscles to the ampulla.

the sublingual glands are paired anteriorly. they are poorly seen in their entirety and have multiple small ducts (8-20) superiorly.

this grays anatomy diagram demonstrates the relative positions of the salivary glands.

submandibular gland

submandibular gland scan plane

the normal submandibular gland is homogeneous in echotexture.

intra-oral scanning:

  • can assist with assessing the ampulla and papilla.
  • use a probe with a small footprint (hockey stick is ideal).
  • some patients will not be able to tolerate this technique as they feel like “gagging”.
  • remove any false teeth as this will improve the area for you to scan in.
  • get the patient to roll their tongue back out of the way.
  • ensure the probe is covered in a non latex cover .
  • the patient is required to hold a small amount of water in floor of their the mouth to scan to scan through.
  • inform the patient to tap you on the arm if they need you to stop or they need to swallow.

intra-oral view of the wharton’s duct ampulla.

sublingual glands

  • the paired sublingual salivary glands lie immediately deep to the mucous membrane under the tongue, anterior to the submandibular glands.
  • they drain primarily via a series of multiple small ducts  that may communicate with the submandibular duct.
  • the glands are relatively small and deep so can sometimes only be seen if there is pathology.

scan plane for ultrasound of the sublingual glands

scan protocol

role of ultrasound

intraglandular and extraglandular lesions to be localised and differentiated.
to identify the cause of:

  • a palpable lump in the gland/neck.
  • the patient can sometimes palpate a stone under the mandible or under their tongue. the stone can block the duct causing infection and swelling.
  • pain
  • mumps
  • illness, including mouth or dental infections
  • mouth dryness
  • abnormality on previous xrays,ct or sialogram
  • guidance of injection, aspiration or biopsy

limitations

  • if the patient cannot lie flat with their neck extended.
  • the sublingual glands may be small and can sometimes only be seen if there is pathology.
  • in some patient’s the entire submandibular gland may be difficult to visualise, hidden behind the mandible. (extend the patients neck, and angle high up beneath the mandible)
  • facial hair (will require alot of gel).

patient preparation

  • low collared shirt
  • may have to remove jewellery around the neck.
  • supine position.
  • towel across the chest/shoulders
  • lie the patient so their head is at the top of pillow and tipped right back.
  • a pillow or towel can be placed under the shoulders.

equipment setup

use of a high resolution 7-14mhz linear transducer. you may need to use a lower frequency or curved linear probe (5-7mhz) to visualise the deep portion of the submandibular or parotid glands.
good colour / power / doppler capabilities when assessing vessels or vascularity of a structure.
be prepared to change frequency output of probe (or probes) to adequately assess both superficial and deeper structures.

common pathology

  • obstruction. calculus or acalculus.
  • acute inflammation
  • sialadenitis – heterogeneous, hypoechoic gland, micro abscesses
  • inflammatory mass – hypoechoic ,ill defined gland, ducts within lesion
  • abscess- frank fluid, gas microbubbles
  • the ultrasound distinction of benign and malignant lesions is not precise but suspicion should be aroused when the lesion is ill defined or locally invading, when it is deep in the lobe, and when neck nodes are present.

scanning technique

submandibular glands

  • supine position.
  • tip the patient’s head back for better access.
  • assess the gland’s echogenicity. it should be hypoechoic with a homogeneous echotexture compared to the surrounding tissue, similar to a muscle’s echogenicity.
  • the intraglandular ducts are small linear hypoechoic parallel stripes.
  • compare both sides .
  • scan the entirety of the gland from midline to lateral and anterior-posterior several times to assess :
    • the size
    • for increased vascularity
    • any abnormality in the surrounding anatomy including the lymph nodes.
    • duct dilatation (use colour doppler so you do not mistake a vessel to be a dilated duct).
  • the duct starts from within the hilum of the gland , follow the duct to the submental region .it is easiest to find it in the superficial portion of the duct which is the medial part of the submandibular gland and runs around the posterior border of the myohyoid muscle. then medial to the sublingual gland to the papilla at the floor of the mouth.
  • the kuttner lymph node is between the parotid and submandibular gland.

optional intra-oral scanning:

  • can assist with assessing the ampulla and papilla.
  • use a probe with a small footprint (hockey stick is ideal).
  • some patients will not be able to tolerate this technique as they feel like “gagging” .
  • remove any false teeth as this will improve the area for you to scan in.
  • performed with the patient erect
  • get the patient to roll their tongue back out of the way.
  • ensure the probe is covered in a non latex cover.
  • the patient is required to hold a small amount of water in floor of their the mouth to scan to scan through.
  • inform the patient to tap you on the arm if they need you to stop or if they need to swallow.

sublingual glands

  • are best visualised in transverse and longitudinal planes obtained from the submental position.
  • the average size of the normal gland is 32 x 12mm.
  • the gland is obscured anteriorly by the mandible.
  • usually the sublingual ductal system cannot be visualised.
  • the sublingual glands are visualised submentally.

they are deep to the mylohyoid and lateral to the geniohyoid/genioglossus.

echogenicity

  • homogeneous
  • hyperechogenicity similar to the parotid gland.

always scan both sides for symmetry.

  • have the pts head extended.
  • must scan all nodal regions.
  • colour doppler may also aid in the assessment of malignancy; the lesion with a disorganised colour doppler flow pattern and ri >0.8, pi >2 is more likely to be malignant.

basic hardcopy imaging

a salivary gland series should include the following minimum images:

  • submandibular gland, long & trans
  • submandibular duct
  • parotid gland, long & trans
  • accessory parotid gland
  • right side of the neck
  • left side of the neck
  • document the normal anatomy. any pathology found in 2 planes, including measurements and any vascularity