Study Notes on Glands of the Head, Neck, and Tongue

Glands of the Head, Neck, and Tongue

Overview of Glands

  • Glands of the Head and Neck
    • Endocrine Gland
    • Usually ductless
    • Drains into bloodstream, distributed to distant body locations
    • Examples: thyroid, pituitary, parathyroid
    • Exocrine Gland
    • Has an associated duct
    • Excretion travels down duct, deposited where needed
    • Types include:
      • Major Salivary Glands
      • Minor Salivary Glands
      • Sebaceous Glands
      • Lacrimal Glands

Major Salivary Glands

  • Components of Major Salivary Glands
    • Acini
    • Secretory end that produces proteins
    • Ends in grape-like clusters
    • Types of Acini:
      • Serous Acini
      • Produce thin, watery secretion
      • Primary source of protein Amylase, which converts starch and glycogen into simple sugars
      • Mucous Acini
      • More viscous secretion, contains mucins
      • Product is 99% water, contains inorganic ions (sodium, potassium, chloride)
      • Seromucous Acini
      • Contain both serous and mucous components, secrete between cell walls
    • Connective Tissue Capsule
    • Surrounds the gland, contains blood/nerve/lymphatic supply
    • Septums separate acini into lobules
    • Duct System
    • Controlled by the autonomic nervous system
    • Types of intralobular ducts:
      • Intercalated Ducts
      • Small ducts that drain directly to acini
      • Striated Ducts
      • Allow for resorption of water and inorganic components back into blood supply

Minor Salivary Glands

  • Structure
    • Similar to major glands, but smaller with reduced duct systems
    • Function to keep tissues moist
    • Either serous or mucous
  • Location
    • Labial Glands (labial mucosa)
    • Buccal Glands (buccal mucosa)
    • Lingual Glands (tongue-anterior, Von Ebner, posterior)
    • Sublingual Glands (floor of the mouth)
    • Palatal Glands (hard palate)
    • Glossopalatine Glands (soft palate, tonsils)
    • Duct System
    • No duct system

Major Salivary Glands Locations and Functions

  • Parotid Gland
    • Only secretes serous saliva
    • Located along the masseter muscle, behind the mandible ramus
    • Largest salivary gland, producing 25% of saliva
    • Duct opens opposite the maxillary second molar via Stenson's Duct
  • Sublingual Gland
    • Secretes seromucous saliva (mixed gland; 2/3 serous cells making saliva slightly viscous)
    • Produces 60-65% of total saliva
    • Located below and slightly behind the body of the mandible
    • Duct runs forward in the mouth and opens to the sublingual caruncle
  • Submandibular (Submaxillary) Gland
    • Mainly mucous saliva
    • Produces 10% of total saliva, most viscous
    • Located in anterior portion of mandible, next to canines
    • Secretes through one major duct and several smaller ducts along the sublingual fold

Functions of Saliva

  • Assists in swallowing
  • Assists in speech
  • Helps buffer pH in the oral cavity
  • Lubricates and protects oral tissues
  • Xerostomia
    • Condition characterized by minimal or no salivary flow
    • Can lead to issues such as dry fissured tongue

Tongue Anatomy

  • Formation of the Tongue
    • Structure: A sac of epithelium filled with muscles
    • Germ Layer: Endoderm
    • Developmental Origins:
    • Anterior 2/3 arises from the first pharyngeal arch
    • Posterior tongue from the third pharyngeal arch
    • Root from the fourth pharyngeal arch

Lingual Papillae of the Tongue

  • Types:
    • Filiform
    • Most numerous on the body
    • Features: Pointed structure covered by keratinized epithelium, no taste buds
    • Fungiform
    • Lesser quantities than filiform; contains taste buds
    • Mushroom-shaped with possible physiological pigmentation
    • Foliate
    • Located on lateral margins, contains taste buds
    • Leaf-shaped structure
    • Circumvallate
    • Large, raised structures with taste buds; surrounded by a trough with von Ebner glands

Lingual Tonsils

  • Location
    • Base of the tongue, dorsal surface, posterior to Circumvallate Papilla
  • Characteristics
    • Non-encapsulated masses of lymphoid tissue
    • Located in the lamina propria layer of oral epithelium

Glands of the Tongue

  • Lingual Glands
    • Located in the anterior portion of the tongue
    • Provide moisture for speech, chewing, etc.
  • Von Ebner Glands
    • Located at the posterior of the tongue
    • Function to rinse the taste buds

Appearance of the Tongue

  • Healthy/Normal Tongue
    • Characteristic of a smooth, pink surface
  • Unhealthy/Abnormal Tongue
    • May exhibit a peeling, discolored coating

Muscles of the Tongue

  • Extrinsic Muscles of the Tongue

    • Hyoglossus
    • From hyoid bone to lateral surface of the tongue; pulls sides down flat
    • Styloglossus
    • From styloid process to lateral surface; elevates and retracts tongue
    • Palatoglossus
    • From soft palate to tongue; elevates back of tongue
    • Genioglossus
    • From genial tubercles of mandible to midline; protrudes and depresses the tongue

  • Intrinsic Muscles of the Tongue

    • Superior Longitudinal Group
    • Runs anterior to posterior, lies near dorsum; moves tongue forward/backward
    • Inferior Longitudinal Group
    • Runs anterior to posterior, lies near ventrum; moves tongue downward
    • Transverse Group
    • Runs side to side; narrows tongue
    • Vertical Group
    • Runs dorsum to ventrum; flattens the tongue