Pharynx and larynx Flashcards
1
Q
Embryology of pharynx and larynx
A
- Oral and nasal cavities are ectodermally derived, and thus are innervated by somatosensory (V1 and V2 for nasal cavity, V2 and V3 for oral cavity)
- Foregut derivates (pharynx, esophagus, larynx, and trachea) are endodermally derived and thus innervated by viscerosensory (IX and X)
2
Q
Orientation of upper digestive and respiratory tracts
A
- Nasal cavity extends from anterior nares (nostrils) to posterior nasal aperture (Choanae)
- Oral cavity extends from mouth to orophharyngeal isthmus (remnant of buccopharyngeal membrane) btwn the palatoglossal folds
- Pharynx is the first part of the foregut and is divided into 3 parts
3
Q
Nasopharynx
A
- Located behind the nasal cavity and above the soft palate
- Lateral wall contains opening of the eustachian tube, who’s medial end projects into nasopharynx as torus tubarius
- Behind torus tubarius is the pharyngeal recess
- Pharyngeal tonsils in roof of nasopharynx
4
Q
Oropharynx
A
- From below the soft palate (behind oral cavity) to the epiglottis
- Palatine tonsils located btwn the palatoglossal (anterior) and palatopharyngeal (posterior) folds
- Lingual tonsils, foramen cecum, and epiglottic vellecula are all located in the posterior 1/3rd of the tongue
5
Q
Laryngopharynx
A
- From the epiglottis to the inferior part of cricoid cartilage
- Contains the piriform recess (space on either side of laryngeal inlet)
- Esophagus begins at the lower edge of the cricoid cartilage
- Larynx is the upper part of the lower respiratory path and begins at the laryngeal inlet and continues to the trachea (lower edge of cricoid cartilage)
6
Q
Sensory innervation of cavities and pharynx/larynx 1
A
- Somatosensory only present in oral and nasal cavities
- The nasociliary nerve (branch of V1) branches innervate the anterior 1/3rd of the nasal cavity
- The greater palatine branches (V2) innervate the posterior 2/3rds of the nasal cavity
- Viscerosensory to parts of the nasopharynx (eustachian tube mucosa) is from IX
7
Q
Sensory innervation of cavities and pharynx/larynx 2
A
- Somatosensory to the oral cavity is divided in half, greater/lesser palatine nerves (V2) innervate the top of the oral cavity (hard and soft palates)
- The lingual branch of V3 innervates the tongue (inferior alveolar branch innervates lower teeth)
- Lingual nerve also carries taste from chord tympani to anterior 2/3rds of tongue, and para/pre to submandibular ganglion (to submandibular gland), then para/post to sublingual gland
- The oropharynx contains viscerosensory innervation (for gag reflex) which is communicated thru IX
- IX also provides taste to posterior 1/3rd of tongue
8
Q
Sensory innervation of cavities and pharynx/larynx 3
A
- At the epiglottis, X innervates the epiglottic vellecula (viscerosensory) to induce cough reflex (will cause the same reflex in larynx)
- X also supplies taste to epiglottis (all via internal branch of superior laryngeal nerve)
- The glottis is the region btwn (and including) the true vocal folds, this area separates the supraglottic region (internal branch of superior laryngeal nerve) form the infraglottic region (recurrent laryngeal nerve)
- Recurrent laryngeal nerve will give para/pre and viscerosensory to the laryngopharynx, infraglottic region of larynx, esophagus and trachea
- Internal branch of sup. laryngeal only does supraglottic region (of larynx)
9
Q
Fascia of the pharynx and larynx
A
- Visceral structures of the neck are surrounded by the pretracheal fascia
- These structures are separated by vertebral column and associated muscle (surrounded by pre vertebral fascia) by the retropharyngeal space
10
Q
Tonsils
A
- Collection of lymphoid tissue
- Pharyngeal tonsils: btwn the roof of the nasopharynx and the spheno-occipital bone of cranial base
- Can obstruct normal air flow when enlarged (adenoids)
- Palatine tonsils: protruding masses located btwn palatoglossal and palatopharyngeal folds
- Lingual tonsils: lymphatic nodules causing a roughened surface on the posterior part of the tongue
11
Q
Pharyngeal muscles
A
- All are innervated by X except stylopharyngeus, which is innervated by IX
- Stylopharyngeus projects from styloid process and inserts btwn the superior and middle pharyngeal constrictor muscles
- Pharyngeal constrictors (superior, middle and inferior) insert into the pharyngeal raphe
- The lowest of the constrictor muscle (inferior to the inferior constrictor muscle) is the cricopharyngeus muscle (innervated by branches of X)
12
Q
Valves of the pharynx
A
- Eustachian tube connects the nasopharynx to the middle ear (normal closed) is opened by muscles of the soft palate and pharynx during swallowing
- Regurgitation of food from oropharynx to nasopharynx during swallowing is prevented by stiffening and raising the soft palate (tensor vili palatini by V3 and levator vili palatini by X)
- Preventing food from going back into oral cavity from oral pharynx: tongue pressing against palate
- Preventing food from entering the larynx: epiglottis is depressed over the laryngeal opening
- Gag reflex to oropharynx: IX (viscerosensory)
- Cough reflex to larynx: X (viscerosensory)
13
Q
Cartilage of the larynx
A
- Thyroid cartilage: contains the laryngeal prominence (adam’s apple) and is bordered superiorly by the hyoid bone and inferiorly by the cricoid cartilage
- Arytenoid cartilage sits on the upper edge of the posterior side of the cricoid cartilage
- Vocal ligaments stretch from the arytenoid cartilages to the inside of the thyroid cartilage (continuous w/ cricothyroid membrane)
14
Q
Joints of the larynx
A
- Cricothyroid joints: allows rocking (tilting) of the thyroid cartilage relative to the cricoid cartilage
- Results in stretching of the cricoid cartilage due to contraction of cricothyroid muscles
- Cricoarytenoid joints: allows for abduction and adduction of the true vocal chords due to contraction of the posterior cricoarytenoid muscles
15
Q
Cricothyroid muscles
A
- Stretches vocal cords, located on lateral side btwn the cricoid cartilage and thyroid cartilages
- Innervated by the external branch of the superior laryngeal nerve (X)
