Submandibular Triangle Flashcards
What is the base of the submandibular triangle?
the inferior border of the mandible
What are the sides of the submandibular triangle?
the anterior and posterior bellies of the digastric muscle
What nerve innervates all the intrinsic and all the extrinsic muscles of the tongue (except for palatoglossus)?
CN XII
What nerve innervates palatoglossus?
CN X
What are some of the roles of the mylohyoid muscles?
supporting the floor of the mouth, enabling the tongue to press against the palate in swallowing, and also raising the hyoid
What are some of the roles of the geniohyoid muscles?
supporting the hyoid bone, pulling it anteriorly and a bit upward
What is the origin of the geniohyoid?
inferior mental spine of the mandible (inserts at the hyoid bone)
What is the origin of the mylohyoids?
the mylohyoid line of the mandible (inserts of the hyoid bone)
What muscles lie on the superficial surface of the mylohyoids?
the anterior digastric m.
What is the mylohyoid innervated by?
nerve to mylohyoid, a branch of the mandibular division of CN V (V3)
What does the nerve to mylohyoid branch from?
the inferior alveolar n. as that nerve enters the mandibular foramen
Where does the n. to mylohyoid run? Along with?
in the mylohyoid groove along with the mylohyoid branch of the inferior alveolar artery
What other muscle does the n. to mylohyoid innervate?
the anterior digastric belly
What is the posterior digastric belly innervated by?
facial nerve
Why do the anterior and posterior digastric bellies have different innervation?
because they are derived from different pharyngeal arches, I and II
What muscle attached to the superior mental spines of the mandible?
genioglossus
What muscle attached to the inferior mental spines of the mandible?
geniohyoid
What muscle inserts at the digastric fossa?
the anterior digastric
What are the possible actions of contraction of the geniohyoid?
the geniohyoid muscles can either pull the hyoid anteriorly and slightly superiorly, but if the hyoid bone is fixed in place by contraction of the infra hyoid muscles, contraction can help to depress the mandible
What is the innervation of geniohyoid?
C1 from the cervical plexus (that runs partially with the hypoglossal nerve)
What nn. run with the hypoglossal nerve during their course?
the nerve to geniohyoid, nerve to thyrohyoid, and superior root of the nasa cervicalis. The branch of C1 to the geniohyoid extends with the hypoglossal the furthest
What are the extrinsic muscles of the tongue?
genioglossus, hyoglossus, styloglossus, and the palatoglossus
What are the insertion points of the genioglossus?
primarily in the lateral aspect of the intrinsic tongue muscles but some fibers insert on the hyoid bone
Contraction of different groups of genioglossus fibers have different effects on the tongue. What does contraction of its inferior fibers cause?
projection of the tongue out of the mouth, called protraction of the tongue
What does contraction of the superior fibers of the genioglossus cause?
pulls the tip of the tongue back inside the mouth and downward, called retraction of the tongue
What does contraction of all of the fibers of the genioglossus, contraction of the intrinsic fibers, and other supporting muscles, such as the mylohyoids cause?
causes the tongue to protrude superiorly, pushing against the palate, an action important for propelling a bolus of food posteriorly toward the pharynx
What does contraction of the hyoglossus cause? Where does it span
the hyoglossus spans between the greater horn of the hyoid bone and runs anteriorly and superiorly to blend in with the tongue.
Contraction pulls down on the sides of the tongue and a retractor of the tongue, often flattening the tongue
What muscle blends into the side of the tongue close to the hyoglossus?
the styloglossus
What does contraction of the styloglossus cause?
it pulls the tongue posteriorly
What is the anterior tonsillar pillar?
the boundary between the oral cavity and the oropharynx
What muscle forms the anterior tonsillar pillar?
palatoglossus (only tongue muscle innervated by CN X)
If a person had a lesion of the left hypoglossal nerve, which side would the tongue protrude to if you stuck it out?
the left
The deep part of the submandibular gland wraps around which muscle?
the posterior free margin of the mylohyoid
Which part of the submandibular gland does the duct originate from?
the deep part
Where does the submandibular duct end?
at the sublingual caruncle in the floor of the oral cavity under the tongue. This is where the submandibular gland saliva is secreted. A sublingual caruncle lies on either side of the frenulum
Where does the lingual nerve (branch of V3) originate?
the infratemporal fossa
Which gland most commonly develops stones?
the submandibular gland
What muscle does the lingual nerve descend down at the level of the tongue?
the styloglossus (and slightly on the very superior, lateral aspect of the hyoglossus)
The submandibular ganglion is located where?
directly inferior to the lingual nerve, sandwiched in between that and the deep part of the submandibular gland
Does the lingual artery course superficial or deep to the hyoglossus?
deep to it
What is the function of the lingual nerve?
GSA innervation to the anterior 2/3 of the tongue (to circumvallate papillae) and GSA to the floor of the mouth and lingual gingiva of the mandible
Where are the cell bodies of the lingual nerve fibers?
in the semilunar ganglion located in the middle cranial fossa
Note on the distribution of the lingual artery and veins in relation to the hyoglossus
the artery is completely deep to the hyoglossus while lingual veins exist on both the superficial and deep surfaces of the hyoglossus. Veins drain to the IJV
What provides SA innervation to the taste of the anterior 2/3rd of the tongue and GVE parasympathetic to the submandibular and sublingual glands?
CN VII
Where are the cell bodies of the lingual nerve?
in the trigeminal ganglion (aka semilunar, aka Gasser’s). This a sensory ganglion
What provides GSA innervation to the posterior 1/3 of the tongue?
via CN IX
Where do the sensory ganglia of CN IX and X lie?
within or just below the jugular foramen (superior is within, inferior is just below)
What branch of CN VII carrier SA taste fibers from the anterior 2/3 of the tongue?
the chorda tympani branch
remember that GSA to the anterior 2/3rd is from the lingual nerve
Where are the cell bodies of SA fibers of the tongue found?
within the geniculate ganglion, the peripheral ganglion of the 7th nerve
SA and GSA for the posterior 1/3 of the tongue is from what nerve?
CN IX
What does the chorda tympani branch of CN VII do?
SA taste fibers to the anterior 2/3 of the tongue and preganglionic parasympathetic fibers from one of the motor nuclei of VII in the brain to the submandibular ganglion. Postganglionic fibers then run from the submandibular ganglion to the submandibular and sublingual lands to provide GVE parasympathetics
What nerve does the chorda tympani run with?
the lingual nerve, having joined it in the infra temporal fossa
Which is deep to the superficial submandibular gland, the facial artery or facial vein?
the facial artery
What foramen does the chorda tympani branch of the facial n. come through?
the stylomastoid foramen
Where does the chorda tympani nerve run before joining with the lingual n.?
the infratemporal fossa
Describe the course of the chorda tympani n.?
It comes off the brain, through the IAM, through the facial canal in the temporal bone and has its sensory ganglion in the geniculate ganglion. It then goes through SMF into the infra temporal fossa and then meets up with the lingual n. to go the anterior 2/3 of the tongue
The lingual n. is a branch of?
V3
What is achalasia?
failure of the lower esophageal sphincter to respond to the swallowing reflex
