Oral cavity and larynx week 3 Flashcards
Identify the labeled structures.
What forms the roof, floor, and walls of the oral cavity?
What nerve(s) innervate the walls of the oral cavity?
The roof is formed by the hard and soft palates.
The floor is formed mainly by the tongue and muscles lying just below the tongue and the lateral walls (a.k.a. cheeks) are muscular.
Walls (cheeks) of the oral cavity. Buccinator muscle and muscles of facial expression form the walls of the oral cavity and are innervated by the facial nerve [VII]. However, general sensation from the skin and oral mucosa of the cheeks is carried by the buccal branch of the trigeminal nerve (V3).
What separates the oral and pharyngeal parts of the tongue?
What is the intrinsic muscle of the tongue? What nerve is it innervated by?
What muscle composes the root of the tongue? What is the root of the tongue attached to?
What are the extrinsic muscles of the tongue? What are they innervated by?
The genioglossus muscle is considered the intrinsic tongue muscle and can be further subdivided into 4 parts based on fiber orientation. However, you are not responsible for learning the 4 parts.
The root of the tongue is attached to the mandible and the hyoid bone and is composed of the genioglossus muscle which is innervated by the hypoglossal nerve.
Extrinsic muscles originate elsewhere, but all insert into the tongue to assist tongue movements:
- palatoglossus muscle (innervated by CN X).
- hyoglossus muscle (innervated by CN XII).
- styloglossus muscle (innervated by XII).
Note that all muscles of the tongue are innervated by CN XII with the exception of the palatoglossus (innervated by CN X).
What 2 muscles form the floor of the oral cavity? What are they innervated by?
Just beneath the tongue lies the geniohyoid muscles which are paired cord-like muscles on either side of the midline. The lie between the tongue (genioglossus) and mylohyoid muscle. The mylohyoid muscle forms a muscular diaphragm supporting the geniohyoid. Both the geniohyoid and mylohyoid muscles extend from the mandible to the hyoid bone. (Think of the geniohyoid as a person lying on a hammock, the mylohyoid, with the head touching the mandible and the feet resting on the hyoid and you will get the relationship!) The mylohyoid is innervated by the trigeminal nerve (CN V) via V3 and the geniohyoid is innervated by a branch of C1.
State what type of innervation and the specific structures of the oral cavity (tongue, floor, palate) innervated by the nerves listed below. If applicable, name specific branches of the nerves:
Trigeminal
Facial
Vagus
Glossopharyngeal
Hypoglossal
Four cranial nerves play a role in supplying innervation to the oral cavity and sublingual region: Trigeminal (CV V), Facial (CN VII), Glossopharyngeal (CN IX), Vagus (CN X) and Hypoglossal (CN XII).
A. Trigeminal nerve CN V
General sensory innervation
- V2 - upper parts of the cavity, palate and upper teeth
- V3 - lower parts of the oral cavity, lower teeth, anterior 2/3 of the tongue
Motor innervation
• V3 – motor for tensor veli palatini and mylohyoid muscles
Facial nerve CN VII
- Taste for the anterior 2/3 of the tongue; these fibers are distributed by branches of V3 (lingual nn)
- Parasympathetic to glands within the oral cavity (sublingual and submandibular); also distributed by branches V3 (lingual nn)
B. Vagus CN X
- Motor for all muscles of the soft palate EXCEPT tensor veli palatini (innervated by a branch of V3)
- Motor to palatoglossus muscle
C. Glossopharyngeal nerve CN IX
• Taste (SA) and general sensation for posterior 1/3 of the tongue
D. Hypoglossal nerve CN XII
- Motor for all muscles of the tongue EXCEPT the palatoglossus (innervated by CN X)
- a branch from Cl joins CN XII and then leaves to innervate the thyrohyoid and geniohyoid muscles
What muscle is the parotid duct superificial to?
What structures may be compressed with inflammation of the parotid gland?
- The parotid duct passes across the masseter muscle and penetrates the buccinator muscle opening into the oral cavity adjacent to the crown of the second upper molar tooth.
- An important relationship to remember is that the parotid gland encloses the external carotid artery, retromandibular vein and part of the facial nerve CN VII. These structures can be compressed and their function impaired when the parotid gland is swollen.
Where do the submandibular glands open into the oral cavity? What nerve is related to the submandibular duct?
What is the relationship of the sublingal gland to the submandibular duct?
- Submandibular glands are “hook-shaped” with the duct opening beside the base of the frenulum of the tongue. An important relationship to remember is that the lingual nerve loops under the submandibular duct.
- Sublingual glands are the smallest of the 3 paired salivary glands. They lie lateral to the submandibular duct and lingual nerve and have 2-3 openings into the floor of the oral cavity.
Explain the sympathetic and parasympathetic innervation of glands above the oral fissure, below the oral fissure, and the parotid gland.
Glands above the level of the oral fissure:
- preganglionic parasympathetic fibers originate in CN VII; synapse in the pterygopalatine ganglion and travel with branches of the trigeminal nerve (CN V).
- postganglionic sympathetic fibers join branches of V2 (e.g. greater palatine nerves) or travel with adjacent arteries.
Glands below the level of the oral fissure
- preganglionic parasympathetic fibers originate in CN VII; travel with the Chorda Tympani Nerve and join the Lingual Nerve (of V3); and synapse in the submandibular ganglion.
- postganglionic parasympathetic fibers pass directly to the submandibular and sublingual glands.
- postganglionic sympathetic fibers join branches of the trigeminal nerve CN V or travel with adjacent arteries.
Parotid gland :
- preganglionic parasympathetic fibers originate in CN IX; synapse in the otic ganglion and postganglionic parasympathetic fibers join a branch of V3 (auriculotemporal nn) to reach the gland.
- postganglionic sympathetic fibers join branches of the trigeminal nerve CN V or travel with adjacent arteries.
attached is pg 12 of course notes
The Chorda Tympani branch of CN VII (facial) exits via ___ _____ and “jumps” on lingual nerve.
The Chorda Tympani branch of CN VII (facial) exits via petrotympanic fissure and “jumps” on lingual nerve.
It “rides” to submandibular ganglion and synapses. This describes motor innervation (GVE). What sensory fibers are in the chorda tympani?
What are the main cartilages of the larynx?
What are the lesser cartilages of the larynx?
Where are they located?
main cartilages: epiglottis, thryoid cartilage, cricoid cartilage
lesser cartilages: arytenoid cartilage, corniculate cartilage, cuneiform cartilage
Epiglottic cartilage
- behind the root of the tongue and hyoid bone
- lies in front of the inlet or aditus of the larynx
Thyroid cartilage - Gr.,thyreos = shield shaped door
- superior thyroid notch
- laryngeal prominence (or Adam’s apple)
- superior and inferior horns
Cricoid cartilage
•completely formed cartilage encircling the larynx
“Lesser cartilages” – (not in attached pic).
- Arytenoid cartilage - 3-sided pyramid (see essential anatomy)
- Corniculate cartilage
- Cuneiform cartilage (corniculate and cuneiform cartilages lie within the aryepiglottic folds)
What structures does the quadrangular membrane extend between? What is the free edge of the quadrangular membrane called?
What are the vestibular (ventricular) ligaments formed by? What are they also known as? What is their relationship to the true vocal folds?
What does the vocal ligament lie within? What is its relationship to the vestibular folds?
What structures does the conus elasticus extend betwee?
- The Thyrohyoid membrane extends between hyoid bone and thyroid cartilage
- The Quadrangular membrane has a free edge which extends between the epiglottis and arytenoid cartilages. The free edge is called the aryepiglottic folds.
- The Vestibular (ventricular) ligaments are also known as the false vocal folds. They are superior to the true vocal folds and are formed by the lower edge of the quadrangular membrane.
- The Vocal ligament is within the true vocal folds which lie inferior to the vestibular folds.
- The Conus elasticus extends inferiorly from the true vocal folds to trachea.
- Note that the true vocal folds are more medial.
What 3 parts is the laryngeal cavity divided into?
upper chamber (vestibule)
middle chamber (ventricles)
lower chamber (infraglottic space)
What does the vestibule extend from?
What does the laryngeal inlet extend from?
Upper chamber (Vestibule) extends from the inlet to the vestibular folds
- The laryngeal inlet (aditus) leads from the laryngopharynx into the vestibule of the larynx.
- The aryepiglottic folds extend from the epiglottic to the arytenoid cartilages.
- The vestibular folds are called “false vocal cords“ and form the inferior edge of quadrangular membrane.
What does the middle chamber (ventricle) extend from?
What are saccules?
What is the glottis formed by?
Where do the vocal folds lie within the ventricle?
Middle Chamber (Ventricle) extends from the vestibular folds to the glottis.
- The ventricles are spaces that lie between the vestibular and vocal folds.
- The saccules diverticulate upward from the ventricle and produce secretions lubricate the vocal folds.
- The glottis is formed by the vocal folds + rima glottidis (space between vocal folds). The vocal folds are the “true vocal cords” and lie at the inferior end of the ventricle. The actual vocal cords extend between the inner angles of the thyroid laminae and the vocal process of the arytenoid cartilages.
What does the lower chamber (infraglottic space) extened between? What are its walls formed by?
Lower Chamber (Infraglottic Space) lies between the rima glottidis and the trachea.
- It walls are formed by: conus elasticus : cricothyroid ligament: cricoid cartilage
What are the 3 areas of closure of the larynx? How/when do they close?
- The inlet - the epiglottis and aryepiglottic folds form a purse-string-like aryepiglottic sphincter that closes during deglutition to protect the respiratory passages against the invasion of food
- The vestibular folds – can assist in trapping air and making it possible to produce an increased intrathoracic pressure as employed in coughing or increased intra-abdominal pressure that assists in micturition (urination).
- The vocal folds - occurs in phonation or asphyxiation.
Identify the indicated structures.
posterior cricoarytenoid: opens the glottis (the only abductor of the larynx)
transverse arytenoid: closes the glottis
What nerves provide sensory innervation to the laryngeal mucosa? To what parts of the larynx do they each innervate?
What nerve provides parasympathetic innervation to the larynx? What is the purpose of this parasympathetic innervation?
What nerves provide motor innervation to the larynx? What parts?
Sensory
- Internal laryngeal branch of the superior laryngeal nerve - Supraglottic mucosa - (from the inlet down to the vocal folds)
- Recurrent laryngeal nerves - Infraglottic mucosa (below the vocal folds).
Autonomic
- Sympathetic - postganglionic fibers from the superior cervical ganglion
- Parasympathetic - laryngeal branches (CN X) for secretory glands
Motor - Vagus nerve (X)
- Recurrent laryngeal nerve - all intrinsic muscles.
- External laryngeal branch of the superior laryngeal nerve - Cricothyroid muscle (and inferior pharyngeal constrictor).
Explain the arterial supply of the larynx.
Explain the venous drainage of the larynx.
The arterial supply to the larynx comes primarily from the superior laryngeal (from superior thyroid artery) and the inferior laryngeal (from the inferior thyroid artery). Remember that there are numerous anastomoses to ensure an abundant blood supply. see essential anatomy
Venous drainage of the larynx includes Superior laryngeal veins that drain into superior thyroid veins and on to the internal jugular veins and Inferior laryngeal veins that drain into inferior thyroid veins and on to the brachiocephalic trunk.
