Base of Skull/Pharynx/Retropharyngeal space Flashcards
Retropharyngeal space (concern for dissection secondary to abscess)
ID and innervation
ID and innervation
The cricopharyngeus m. is sometimes stretched (surgically)
Pharyngeal plexus
Motor fibers are from CN X (vagus n.)
Sensory innervation fibers are from CN IX (the glossopharyngeal n.)
ID and innervation (Superior to inferior)
Mid pharyngeal constrictor - connects to the hyoid bone
Constrictors are all innervated by the vagus n.
Remember the lungs/trachea are anterior outpocketing of the pharynx (embryologically)
ID and innervation
ID and innervation
Sup. pharyngeal - anteriorly connects to buccinator with pterygomand raphe
Middle pharyngeal - connects anteriorly to the hyoid bone
Inferrior pharyngeal constrictor - connects anteriorly to the thyroid cartilage
How to ID CN XII
The hypoglossal n. runs under the posterior belly of the digastric m.
Anterior scalene lives just anterior to components of the brachial plexus
The phrenic nerve lives anterior to the anterior scalene
Whats the first sign of an acoustic neuroma?
Acoustic neuorma - tumor of CN VIII
Tinnitus - 1st
Balance issues - second
Chorda tympani runs between the handle of the malleus and the incus (internal to the malleus and external to the incus)
Goes into the anterior wall of the middle ear cavity, coming out of the petromandibular fissure right into the mandibular fossa
Chronic middle ear infections can damage what important neurological structure?
The chorda tympani
Trauma to the mandible can damage what nerve?
The chorda tympani - the head of the mandible can fracture the mandibular fossa, injuring the chorda tympani as it exits the petromandibular fissure
How does the eustachian tube run?
What direction
From the middle ear, out the anterior wall and into the pharynx
Tensor tympani
Innervated by CN V-3 (mandibular branch) and attaches to the malleus
Tenses the malleus against the tympanic membrane to dampen noise
The stapedius m
Attaches to the stapes to dampen its vibrations
Innervated by CN VII
Where does CN IX exit the skull and enter the middle ear?
CN IX (the glosspharyngeal n.) exits the skull at the jugular foramen and enters the middle ear at the tympanic canaliculis (floor or jugular wall)
The tympanic branch of CN IX is sensory to the medial wall
Exits as the lesser petrosal branch (innervates the parotid)
CN’s IX, X, and XI exit the jugular foramen
Levator palpebrae superiorosus
Skeletal muscle (proximal portion) is innervated by CN III, distal region (superior tarsal m.) is innervated by sympathetic fibers
Horner’s syndrome - partial ptosis (injury or lesions to sympathetic chain)
CN IX
Tympanic branch - sensory to middle ear mucosa
Lesser petrosal branch - parasympathetic to parotid (hitchhikes on auriculotemporal branch of CN V-3)
CN X
CN XI