Week 6: Anatomy-Pharynx and Larynx Flashcards
What are ectodermal derivatives in the upper digestive and respiratory tracts?
- Oral and naval cavities
- lined by somatically innervated mucosa
What is the bucopharygeal membrane?
- membranous partition in development
- separates ectodermally lined oronasal cavity and endodermally lined gut tube
What are the endodermal derivatives in the upper digestive and respiratory tracts?
- foregut: pharynx, esophagus, larynx, and trachea
- viscerally innervated mucosa
- includes derivatives of pharyngeal arches
- thyroid gland (from thyroglossal duct)
- foramen cecum (depression in dorsal tongue): point of attachment of the thyroglossal duct
- trachea-develops from ventral midline of pharynx, inferior to thyroglossal duct, at laryngeal inlet
- upper part of tracheal becomes larynx while lower part bifurcates to primary bronchi
Describe the general orientation of the pharynx and larynx.
- Nasal cavity: from anterior nares (nostrils) to posterior nasal aperture
- Oral cavity: mouth to oropharyngeal isthmus between palatoglossal folds (arches)
- pharynx: first part of foregut, divided into 3 parts (covered in another flashcard)
- Esophagus: begins at lower edge of cricoid cartilage
- Larynx: upper part of lower respiratory tract
- trachea: begins at lower edge of cricoid cartilage
Describe the divisions of the pharynx.
- Nasopharynx
- behind nasal cavity and above soft palate, extends down to back of soft palate and uvula
- lateral wall: Eustachian tube (opening of auditory canal), medial end of tube is torus tubarius
- pharyngeal recess-slit behind torus tubarius
- pharyngeal tonsil: roof of nasopharynx - Oropharynx
- behind oral cavity and below soft palate
- extends down to tip of epiglottis
- palantine tonsils between palatoglossal (connects with uvula) and palatopharngeal folds
- posterior 1/3 of tongue: lingual tonsil, foramen cecum
- vallecula: depressions between base of tongue and epiglottis - Laryngopharynx
- behind larynx
- compressed space that extends from tip of epiglottis to lower border of cricoid
- piriform recess: space on either side of laryngeal inlet
What is the nasopharynx innervated by (sensory)?
-CN IX
also includes middle ear and eustachian tube
What is the nasal cavity innervated by (sensory)?
anterior: V1
posterior: V2
What is the oral cavity innervated by (sensory)?
hard palate: V2/V3
What is the oropharynx innervated by (sensory)?
- gag reflex
- CN IX
What is the laryngopharyx innervated by (sensory)?
CN X Vagus
What is the Larynx innervated by (sensory)?
CN X Vagus, cough reflex
What is the esophagus innervated by (sensory)?
CN X Vagus
What is the trachea innervated by (sensory)?
CN X Vagus
Describe the facia of the pharynx and larynx.
- prevertebral fascia: most posterior, lying next to vertebral column
- visceral (pretracheal) fascia: surrounds pharynx and larynx
- deep cervical (investing) fascia: most anterior
- Retropharyngeal space is between the pre vertebral fascia and visceral fascia
Describe the tonsils of the pharynx.
These form Waldeyer’s ring
- pharyngeal tonsils: roof of nasopharynx
- palatine tonsils: between palatoglossal and palatopharyngeal folds. these are tonsils removed during tonsillectomy
- lingual tonsils: posterior of tongue, in back of sulcus terminals
Describe the sensory innervation of the tongue and floor of oropharynx.
Anterior 2/3: -taste: CN VII via chorda tympani -SS: CN V3 via lingual nerve Posterior 1/3: -taste and SS: CN IX Epiglottis -Taste: CN X via internal branch of superior laryngeal nerve
Which muscle elevates the pharynx?
Stylopharyngeus muscle
- arises from styloid process and inserts into posterolateral pharyngeal wall above hyoid bone
- innervated by CN IX
What are the lowest fibers of the pharyngeal constrictor muscles?
Cricopharyngeus muscle
-innervated by CN X
What are the valves of the pharynx and larynx?
- nasopharynx-middle ear: opens during swallowing
- nasopharynx-oropharynx: prevents regurgitation of food during swallowing by stiffening and raising soft palate
- oral cavity-oropharynx: closed during swelling by pressing tongue against the palate
- oropharynx-larynx: food is diverted around epiglottis, which is depressed over the laryngeal opening
- larynx-trachea: flow of air in and out of lungs controlled by laryngeal muscles
- laryngopharynx-esophagus: cricopharyngeus muscle acts as spinster
What are the steps in the mechanism of swallowing?
Voluntary
1. tongue pushes against hard palate to push bolus posteriorly
2. hyoid and floor of mouth elevate
3. bolus pushed through fauces (oropharyngeal opening)
Involuntary
4. soft palate elevates to seal of nasopharynx
5. base of tongue pushes food posteriorly
6. pharynx is elevated around bolus and larynx is elevated to close laryngeal inlet
7. upper pharyngeal constrictors push bolus downwards
8. food passes into the laryngopharynx around or over the epiglottis
List the cartilages and ligaments of the larynx.
- thyroid cartilage
- has laryngeal prominence (adam’s apple) - cricoid cartilage
- arytenoid cartilages
- muscular process: lateral
- vocal process: points anteriorly - epiglottic cartilage
- attached to inside of thyroid cartilage - vocal ligaments (cords): from vocal process of arytenoid cartilages to inside of thyroid cartilage
- they are free edge of cricothyroid membrane
What are the joints of the larynx?
- cricothyroid joints: synovial joints on each side between thyroid cartilage and lateral side of cricoid cartilage
- allows thyroid cartilage to rock forward relative to cricoid cartilage
- result: stretch (tensing) vocal ligaments - cricoarytenoid joints: synovial joints that allow arytenoids to rotate or slide across upper edge of cricoid cartilage
- rotation: vocal processes adduct or abduct
- sliding: arytenoids slide towards or away from one another, causes vocal cords to close or open
What does the cricothyroid muscle do? What is it innervated by?
- extrinsic muscle of the larynx
- lateral side of larynx
- primary tensor of the vocal cords
- if paralyzed–>hoarseness
- innervated by external branch of superior laryngeal nerve
What does the posterior cricoarytenoid muscle do? What is it innervated by?
- intrinsic laryngeal muscle
- posterior side of cricoid cartilage, converges laterally on arytenoid’s muscular process
- rotates arytenoids as primary abductor of vocal cords
What is the laryngeal inlet?
- opening into larynx from laryngopharynx
- oriented vertically
What is the vestibule of the larynx?
- from laryngeal inlet downwards to level of vestibular folds
- sensory provided by internal branch of superior laryngeal nerve
What is the false (vestibular) vocal folds?
- two thick folds of mucus membranes
- lie just above the vocal folds
- no role in vocalization
What are the ventricles of the larynx?
- recesses of the laryngeal cavity from opening between false and true vocal folds
- ventricular mucosa has mucosal glands that lubricate the vocal cords
What are the true vocal folds?
- contain vocal ligaments and intrinsic laryngeal muscles, responsible for fine control over tenseness of vocal folds
- rima glottidis=sapce between vocal cords
What is the infraglottic cavity?
- extends from vocal folds downwards to bottom of the larynx defined by lower edge of cricoid cartilage
- sensory by recurrent laryngeal nerve
