Anatomy

• Oral cavity functions:

  • Digestion - initial intake of food and fluids
  • Respiration - air entry
  • Speech production
• The palate:

  • Forms inferior border of the nasal cavity
  • Form superior border of the oral cavity
  • Hard bony part at the front = hard palate
  • Soft part with no bone at the back = soft palate
• Tonsils:

  • Round fleshy masses of lymphoid tissue that contain white blood cells
  • Locate in the throat and palate mean they stop germs entering the body via the mouth or nose
  • 4 different types of tonsils
  • All 4 types are collectively called Waldeyer's ring - form a ring around the opening to the throat from the mouth or nose
  • Tonsils are useful part of immune system in very young children - especially adenoids
• The 4 types of tonsils:

  • Palatine - located within the tonsillar bed - the only ones that can be seen unaided when you open your mouth - the ones typically infected and enlarged in tonsillitis
  • Pharyngeal (adenoids) - roof of the nasopharynx - known as adenoids when enlarged
  • Lingual - numerous lymphoid nodules located in the posterior third of the tongue
  • Tubal - lymphoid tissue around the opening of the eustachian tube in the lateral wall of the nasopharynx
• Pharynx:

  • Ring like muscular tube that acts as the passageway for air, food and liquid. Divided into 3 parts:
  • Nasopharynx - top part - in line with nasal cavity
  • Oropharynx - middle part - in line with oral cavity
  • Laryngopharynx (hypopharynx) - bottom part - in line with larynx
• Epiglottis:

  • A leaf shaped plate of elastic cartilage which marks the entrance to the larynx
  • Its stalk is attached to the back of the anterior aspect of the thyroid cartilage
  • During swallowing, the epiglottis flattens and moves posteriorly to close off the larynx and prevent aspiration
• The larynx (voice box):

  • Part of the respiratory system and is divided into 3 parts
  • Upper part = supraglottis - from the inferior surface of the epiglottis to the vestibular folds (false vocal cords)
  • Middle part = glottis - contains vocal cords and 1cm below
  • Lower part = subglottis - from inferior border of the glottis to the inferior border of the cricoid cartilage (beginning of trachea)
• Making voice:

  • Vocal cords are responsible for producing voice
  • They abduct and adduct through innervation from the recurrent laryngeal nerve and external branch of superior laryngeal nerve
  • When we speak the vocal cords adduct and air is forced through making them vibrate. This creates a sound wave that travels through the pharynx, nose and mouth - act as resonating cavities to produce sound
  • The quality of our voice is determined by the size and shape of the vocal cords, and the resonating cavities
  • Pathology that affects the vocal cords or their innervation will result in hoarseness
• Stertor:

  • Partial upper airway obstruction above the level of the larynx
  • Vibration of nasopharynx, oropharynx or soft palate causes low pitched heaving snoring/gasping sound
  • Causes - congestion in mouth and nose e.g. common cold, adenoid hypertrophy, structural abnormalities in back of nasal cavity
• Stridor:

  • Partial airway obstruction of the upper airways at level of larynx/trachea
  • High pitched - often louder on inspiration but can be expiratory or biphasic
  • Acute stridor - epiglottitis, croup (laryngotracheobronchitis), laryngitis, anaphylaxis, neck space abscess
  • Chronic stridor - laryngomalacia (immature floppy larynx in children), subglottis stenosis (prolonged intubation), vocal cord paralysis, subglottic haemangioma, malignancy
• Parotid gland:

  • Just bellow and in front of each ear
  • Largest salivary gland, but doesn't produce the most saliva (25% of total daily production)
  • Produces serious salvia - watery and rich in enzymes
  • Drainage duct opens opposite to upper second molar
  • Facial nerve runs through gland
  • Most common site of salivary gland tumours - usually benign
  • Parotitis is swelling of the parotid gland - most common cause is viral infection e.g. mumps, EBV
• Submandibular gland:

  • Located within the anterior part of the submandibular triangle
  • Second largest salivary gland but produces largest amount of salvia
  • Produces mixed serious and mucous secretions
  • Drainage duct opens under the tongue
  • Duct most susceptible to calculi - torturous length of duct, ascending duct and nature of salivary secretion
• Sublingual gland:

  • Located on the floor of the mouth
  • Smallest salivary gland that produces the least amount of saliva
  • Has several ductal openings - one opens into the submandibular duct under the tongue