HNS59 Pharynx Flashcards
Pharynx
- Semicircular tube
- Lies successively behind nasal cavity (nasopharynx), oral cavity (oropharynx), larynx (laryngopharynx)
Nasopharynx, Oropharynx, Laryngopharynx
Nasopharynx (Clivus-C1):
- Upper border: Clivus (base of skull) (posterior sphenoid + anterior occipital)
- Lower border: C1 vertebrae (level of soft palate)
- Function: part of upper respiratory tract
—> Respiratory epithelium
—> Membranous walls: Static
Oropharynx (C1-C3):
- Upper border: C1 vertebrae
- Lower border: C3 vertebrae (level of epiglottis)
- Function: transit of food
—> Stratified squamous epithelium
—> Striated muscle wall (semicircular muscle): Contract peristaltically
Laryngopharynx (C3-C6):
- Upper border: C3 vertebrae
- Lower border: C6 vertebrae (level of cricoid cartilage)
- Function: transit of food
—> Stratified squamous epithelium
—> Striated muscle wall (semicircular muscle): Contract peristaltically
Below C6: trachea —> L/R bronchi bifurcation (T4/T5)
Oral muscles
- Genioglossus (CN12) (root of tongue)
- Geniohyoid (C1)
- Mylohyoid (CNV3) (floor of mouth)
***Swallowing
- Coordination from Tongue, Soft palate, Pharynx
- Air / Food enter oral cavity
—> Soft palate (elevated) + Laryngeal inlet (closed) —> Gateway
Stage 1 (voluntary): - ***Styloglossus: food pushed upward + backward by tongue
Stage 2 (involuntary): - ***Palatoglossus: constrict opening of oropharynx —> push food further backward
- ***Sealing nasopharynx:
1. Soft palate elevate (Levator veli palatini)
2. Forward movement of pharynx
3. Constriction of Palatopharyngeal folds - ***Elevate Larynx —> closing epiglottis:
1. Stylopharyngeus
2. Salpingopharyngeus
3. Palatopharyngeus
4. Thyrohyoid
Stage 3 (involuntary):
- ***Pharyngeal constrictor muscle (Superior, Middle, Inferior) —> peristalsis
- Cricopharyngeus (CN10) (i.e. UES, part of Inferior pharyngeal constrictor) —> relax to allow food enter esophagus
Overall:
Styloglossus (Tongue elevation)
—> Palatoglossus (Constrictor)
—> Soft palate elevation + Larynx elevation (Stylopharyngeus, Salpingopharyngeus, Palatopharyngeus, Thyrohyoid)
—> Pharyngeal constrictor muscle (Peristalsis) + Cricopharyngeus (UES)
Nasopharynx
- Opening of pharyngotympanic / auditory tube (cartilage)
—> Middle ear
—> in children: auditory tube shorter, more horizontal, wider
—> bacterial invasion from nasal / oral cavity
—> Otitis media (temporary hearing loss)
—> can even spread to mastoid antrum (Mastoiditis) - Tubal elevation (elevated mucosa layer on top of auditory tube)
- ***Salpingopharyngeus muscle
- Salpingopharyngeal fold: muscular layer with mucosa extend down to pharynx
- intermixed with pharyngeal muscle
- attach to auditory tube cartilage -
**Pharyngeal recess / fossa of Rosenmuller
- behind Tubal elevation
- a space next to Salpingopharyngeal fold
- mucosa layer prone to **NPC
- ***CNV2 - ***Pharyngeal tonsils / Adenoids
- superior to Pharyngeal recess / roof of nasopharynx - Tensor veli palatini
- anterolateral to Auditory tube - Levator veli palatini
- posteromedial to Auditory tube
Oropharynx
- ***Palatoglossus muscle
- Palatoglossal arch: boundary between oral cavity and oropharynx
—> origin: roof of soft palate
—> intermixed with tongue muscle
—> muscles of soft palate / tongue
—> Sphincter + Elevate tongue - ***Palatopharyngeus muscle
- Palatopharyngeal arch: intermixed with pharyngeal constrictor muscles (inferiorly)
—> muscles of soft palate / pharynx -
**Palatine tonsils
- Between Palatopharyngeal arch and Palatoglossal arch
- covered by mucosa internally
- separated laterally from carotid sheath by capsule of fibrous tissue
- supplied by Tonsillar branch of **Facial artery (ECA) + **Ascending pharyngeal artery (ECA)
- lymphatics drain into **Jugulodigastric LN (upper deep cervical LN) - ***Lingual tonsils
- posterior to palatoglossal arch - Vallecula
- posterior to tongue
- a space where foreign body can easily trapped - Superior pharyngeal constrictor
- posterior to Buccinator (joined by Pterygomandibular raphe)
- attach to Pterygomandibular raphe, from sides of floor of mouth
- attach to Pharyngeal tubercle - Middle pharyngeal constrictor
- attach to Hyoid bone (angle between greater and lesser horn)
- attach to Pharyngeal tubercle - Inferior pharyngeal constrictor (**Laryngopharynx)
—> **Thyropharyngeus muscle (upper major) —> attach to Oblique line of thyroid cartilage
—> Cricopharyngeus muscle (lower minor) (circular: act as UES —> connects with esophagus —> relax during swallowing) (CN10 of Pharyngeal plexus) —> attach to Cricoid arch
- attach to Pharyngeal tubercle - Buccinator (oral cavity)
- in front of Superior pharyngeal constrictor (joined together by Pterygomandibular raphe)
Salpingopharyngeus, Palatopharyngeus, Stylopharyngeus
Salpingopharyngeus: from cartilage of auditory tube
Palatopharyngeus: from soft palate
Stylopharyngeus: from styloid process
- ALL longitudinal muscles
- attach at Thyroid cartilage
- Action: Elevate larynx during swallowing
Pharyngeal tonsils + Palatine tonsils + Lingual tonsils
Pharyngeal lymphatics / “Tonsillar Ring”
—> ALL drain into Deep cervical LN
Tonsillectomy
Removal of Palatine tonsils
Complications: Extensive bleeding
—> **lateral wall of tonsils
—> Large vein + Tonsillar artery (Facial artery) + **CN9 + ***Internal carotid artery
Soft palate
- Mobile fold attached to posterior part of hard palate
- Uvula: conical projection in midline of soft palate
Muscles of soft palate
- Tensor veli palatini (CNV3: nerve to medial pterygoid)
- anterolateral
- tense up soft palate
- roof of soft palate - Levator veli palatini (Pharyngeal plexus)
- posteromedial
- elevates soft palate
- extend from one side to another
- roof of oropharynx
Contraction of Tensor veli palatini + Levator veli palatini
—> **Elevates soft palate + **Opens auditory tube
- Musculus uvulae (Pharyngeal plexus)
- elevates uvula - Palatoglossus (Pharyngeal plexus)
- elevate tongue
- constrictor - Palatopharyngeus (Pharyngeal plexus)
- elevates wall of pharynx + larynx
- depress soft palate
Pharyngeal plexus
Network of nerves on lateral side of middle constrictor that receives branches from:
- CN9
- CN10
- CN11
- Sympathetic branches form Superior cervical ganglion (from T1)
Motor fibres:
- from cranial root of CN11
- carried by CN10
Sensory fibres:
- from CN9
—> test: touch mucosa of oropharynx —> Gag reflex
Pharyngeal muscles
- Salpingopharyngeus (longitudinal)
- Palatopharyngeus (longitudinal)
- Superior pharyngeal constrictor (circular)
- Middle pharyngeal constrictor (circular)
- Inferior pharyngeal constrictor (circular)
—> Pharyngeal plexus (CN9, 10, 11 + sympathetic component)
(Stylopharyngeus (longitudinal): CN9)
3 constrictor muscles:
- pass backward into a posterior midline raphe just in front of Prevertebral fascia
- enclosed by ***Pharyngeal fascia
- attached at ***Pharyngeal tubercle
- push food into esophagus (except Cricopharyngeus: UES)
- overlap except between Thyropharyngeus / Cricopharyngeus —> **Herniation of pharyngeal mucosa —> **Pharyngeal diverticulum (outpouch to vertebral column: 由Pharynx lumen凸出去後面)
Pharyngeal fascia
2 layers:
- ***Bucopharyngeal fascia (external, thinner)
- ***Pharyngobasilar fascia (internal, thicker)
Posterior to it —> Prevertebral fascia
Space between Bucopharyngeal fascia / Alar part of Prevertebral fascia
—> ***Retropharyngeal space
—> danger space
—> extend downward to posterior mediastinum (Mediastinitis)
Prevertebral fascia
- Prevertebral part (deeper)
- Alar part (posterior to pharyngeal fascia)
Space between Alar part of Prevertebral fascia / Bucopharyngeal fascia —> Retropharyngeal space (potential space)
—> danger space
—> extend downward to posterior mediastinum
