Anatomy and physiology of the throat Flashcards
What are the two components of the oral cavity?
– Oral vestibule (between lips and teeth)
– Oral cavity proper
What are the boundaries of the oral cavity?
– Lips to palatoglossal arch (anterior pillar)
– Palate to floor of mouth/tongue
– Buccal mucosa
What are the functions of the oral cavity?
- Taste
- Mastication - Teeth, tongue
- Speech - Tongue, cheek, lips
- Digestion - Salivary enzymes
- Swallowing - Tongue, hard and soft palate
What nerve innervates the anterior 2/3rds of the tongue?
Lingual nerve (branch of CN V3)
What divided the submandibular salivary duct into the superficial and deep lobe?
Mylohyoid muscle
Describe the two parts of the tongue, their embryological origin and its innervation
Anterior 2/3rd
• From 1st branchial arch
• Sensation by lingual nerve (branch of CN V3)
• Taste by chorda tympani (branch of CN VII)
Posterior 1/3rd
• From 3rd branchial arch
• Supplied by CN IX (glossopharyngeal) nerve
What is the difference between intrinsic and extrinsic tongue muscles?
o Intrinsic muscles (alter shape)
o Extrinsic muscles (alter position) - genioglossus, styloglossus, hyoglossus and palatoglossus.
Describe the nerve supply of the tongue muscles
CN XII: hypoglossal nerve supply all muscles except for palatoglossus – pharyngeal plexus (CN IX - X)
What are the functions of the tongue?
o Taste
o Mastication
o Swallowing
o Speech
What are the 4 muscles of mastication?
o Lateral pterygoid
o Medial pterygoid
o Temporalis
o Masseter
What is the nerve supply for the muscles of mastication?
CN V3 (mandibular branch of trigeminal)
Describe the epithelium of the oropharynx
Stratified, non-keratinised squamous
Describe the oropharynx
The oropharynx is the middle part of the throat that includes the base of the tongue, the tonsils, the soft palate, and the walls of the pharynx.
What has been linked to the recent increase in oropharyngeal cancers?
HPV infections
Describe the nerve supply of the oropharynx
Pharyngeal plexus- CN IX & X
Describe the blood supply of the hypopharynx
Superior Thyroid Artery, the Lingual Artery and the Ascending Pharyngeal Artery.
Describe the nerve supply of the hypopharynx
Pharyngeal plexus- CN IX & X
Describe the hypopharynx
The hypopharynx is the part of the throat (pharynx) that lies beside and behind the larynx. The hypopharynx is the entrance into the esophagus. Food goes from the mouth and through the hypopharynx and esophagus, where it then passes into the stomach.
What are the 3 phases of swallowing?
Oral phase (voluntary) – in oral cavity • Tongue propels food (bolus) into pharynx • Triggering swallowing reflex (afferent: CN V, IX, X – swallowing centre in medulla – efferent: CN VII, X, XII)
Pharyngeal – in pharynx
• Soft palate pulled upwards
• Epiglottis covers the larynx, vocal cord approximate, larynx moves upward
• Upper oesophageal sphincter (UOS) relaxes
• Respiration reflex inhibited
Oesophageal – enters oesophagus
• Once bolus passed UOS, the sphincter constricts
• Bolus propelled downwards by peristaltic motion, reflex via myenteric plexus
What are the afferent fibres that tell the swallowing centre in the medulla to trigger the swallowing reflex?
afferent: CN V, IX, X
What are the efferent fibres that trigger the swallowing reflex?
CN VII, X, XII
What controls the peristaltic reflex of food movement down the oesophagus?
Auerbach’s plexus (or myenteric plexus)
What are the functions of the larynx?
o Part of respiratory tract
o Voice
o Swallowing
What are the 3 parts of the larynx?
o Supraglottis: extends from the superior tip of the epiglottis to the floor of the ventricular fold (junction of respiratory and squamous epithelium).
o Glottis: begins superiorly at the true vocal fold and extends inferiorly to a horizontal plane 5 mm inferior to the vocal cord
o Subglottic: begins 5 mm below the free edge of the true vocal cord and proceeds to the inferior border of the cricoid cartilage
What are the 7 segments of cartilage which make up the larynx?
o Cricoid cartilage
o Thyroid cartilage
o Epiglottis
o Paired arytenoid cartilages (corniculate and cuneiform)
What are the functions of the extrinsic and intrinsic muscles of the larynx?
Extrinsic muscles (infrahyoid, suprahyoid, and thyrohyoid) of the larynx move the entire laryngeal complex while intrinsic muscles regulate movement of the vocal folds.
Describe the motor innervation of the larynx
All intrinsic mucles supplied by recurrent laryngeal nerve except for cricothyroid muscle (external laryngeal nerve)
Describe the sensory innervation of the larynx
o Supraglottic: internal laryngeal nerve
o Glottic and subglottic: recurrent laryngeal nerve
Which nerve close to the larynx has a greater chance of injury?
The left recurrent laryngeal nerve has a longer course since it loops around the aortic arch instead of the right subclavian artery and therefore has a higher risk of injury during operative chest procedures.
Where does the superior laryngeal nerve split and what into?
At the level of the greater horn of the hyoid, the superior laryngeal nerve divides into an internal and an external branch.
The internal branch travels with the superior laryngeal artery through the thyrohyoid membrane and allows supraglottic sensation and increased airway protection.
The external branch supplies subglottic mucosal sensation and motor fibers to the cricothyroid muscle.
What are the 5 components of speech?
Respiration
- Source of energy: air flow
- Inhalation and exhalation
Phonation
- Flow of air through different VC position, tension, vibration & length
Resonation
- Oral/nasal speech balance
- Depend on nasopharynx, nasal cavity & oral cavity
Articulation
- Production of speech determined by action of lips, tongue and jaw
Prosody
- Production of syllable stress and emphasis
- Provide effective speech tone
Describe the production of speech
The pulmonary phase creates the energy flow with inflation and expulsion of air. This activity provides the larynx with a column of air for the laryngeal phase.
In the laryngeal phase, vocal folds vibrate at certain frequencies to create sound that is then modified in the supraglottic/oral/nasal phase. This modified sound is considered a unique individual voice.
Words are formed by the action of the pharynx, tongue, lips, and teeth. Dysfunction in any of these stages can lead to voice changes, which may be interpreted as hoarseness by the patient.
Which area of the brain is associated with prosody?
Prosody is the rhythm, stress and intonation of speech. It is associated with Brodmann areas 44 and 45 (Broca’s area) of the left frontal lobe
