Lecture 4.3 - Muscles of eyes, mastication, soft palate, and tongue Flashcards
What is a lacrimal apparatus?
the path of a tear from the lacrimal gland to the nasal cavity
- lacrimal gland produces tear (parasympathetic from facial nerve)
- lacriman ducts, surface of eye, lacrimale lake/puncta/canaliculi/sac, nasolacrimal duct, nasal cavity inferior to the inferior concha
What are the muscles of eye movement?
- 6 ocular muscles move the eyeball – 4 straight and 2 oblique
- the 4 rectus muscles arise by a common tendinous ring
Where does the tendon of superior oblique muscles run through?
- through a fibrocartilaginous loos called trochlea and then inserts into the sclera of eyeball
Inferior oblique eye muscle (OINA)
O: orbital plate of maxilla
I: sclera of eye
N: Oculomotor
A: elevates and laterally deviates gaze
Superior oblique eye muscle (OINA)
O: common tendinous ring
I: sclera of eye
N: trochlear
A: depresses and laterally deviates gaze
Inferior Rectus eye muscle (OINA)
O: common tendinous ring
I: sclera of eye
N: oculomotor
A: depresses and medially deviates gaze
Lateral Rectus eye muscle (OINA)
O: common tendinous ring
I: sclera of eye
N: abducens
A: laterally deviates gaze
Media Rectus eye muscle (OINA)
O: common tendinous ring
I: sclera of eye
N: oculomotor
A: medially deviates haze
Superior Rectus eye muscle (OINA)
O: common tendinous ring
I: sclera of eye
N: oculomotor
A: elevated and medially deviates gaze
What are the extraocular muscle functions?
- once the eye is adducted, the superior and inferior obliques work best to lower and raise the eye
- once the eye is abducted, the superior and inferior recti work best to raise and lower the eye
What muscles are needed to look directly upwards?
both superior rectus and inferior oblique
What muscles are needed to look directly down?
both inferior rectus and superior oblique
What are the characteristics of the trigeminal nerve and its 3 branches?
- main sensory nerve for head
- motor nerve for the muscles of mastication
- 3 large branches:
- to the area above and media to the eye (sensory)
- the the maxillary region (sensory)
- to the mandibular region (sensory and motor)
What happens if there is a lesion in the trigeminal nerve?
- causes anesthesia of corresponding areas of scalp, face, cornea, conjunctiva, nose, mouth and tongue and also paralysis of muscles of mastication; when mouth is opened mandible moves to paralyzed side
Temporalis (OIA)
O: floor of temporal fossa
I: coronoid process of mandible
A: anterior and posterior fibers elevate mandible; posterior fibers retract mandible
Masseter (OIA)
O: zygomatic arch
I: lateral surface of mandible
A: elevates and protrudes mandible; deep fibers retrude mandible
Medial pterygoid (OIA)
O: tuberosity of maxilla and lateral pterygoid plate
I: medial surface of angle of mandible
N: elevates and help protrude mandible
Lateral pterygoid (OIA)
O: upper head: greater wing of sphenoid; lower head: lateral pterygoid plate
I: neck of mandible and articular disc, capsule of TM jiont
A: protrude mandible and produce side-to-side movement
What muscles are used in protraction/retraction of jaw?
Protraction: lateral pterygoid, little bit of medial pterygoid, masseter
Retraction: posterior fibers of temporalis, deep part of masseter, geniohyoid, digastric
What is the temporomandibular joint (TMJ)?
formed by head of mandible, mandibular fossa, and articular tubercle of temporal bone
What muscles are used in elevation and depression of jaw?
Elevation: (biting movement) temporalis, masseter, medial pterygoid
Depression gravity, lateral pterygoid, digastric, geniohyoid, mylohyoid
What muscles contracts when move the mandible to one side?
- temporal of same side
- medial/lateral pterygoid of opposite side
- masseter of same side
What kind of joint is the TMJ?
- hinge and gliding joint
- forward gliding and hinge-like rotation
- when the mouth is opened, the head and the articular disc move forward until the head lies inferior to the articular tubercle
What is the muscle movement at the TMJ?
- lateral pterygoid pulls head of mandible anteriorly
- head (condyle) and articular disc slide anteriorly
- occurs when mouth opens a lot
- wears on the bone and/or cartilage can cause pain
- can be confused with ear pain
How is the TMJ dislocated and its symptoms?
- TMJ is easily dislocated
- usually dislocates anteriorly, especially when yawning or taking a large bite
- the person is then unable to close the mouth
- also dislocated during tooth extraction or by a blow to the chin when mouth is open (usually bilateral)
How is the TMJ damage occured?
- powerful compressive forces act on TMJ
- can occur from:
- frequently chewing gum
- frequently chewing heard foods like nuts, hard vegetables, toothpicks
- grinding teeth
- nail biting
Which muscles elevate mandible and close mouth?
temporalis, masseter, and medial pterygoid
Which muscles pull mandible anteriorly and opens mouth?
lateral pterygoid and anterior belly of the digastric
Which muscles tenses the floor and roof of mouth
mylohyoid and tensor veli palatini
What does the oral palate form? What does it consist of?
- forms the roof of the mouth and floor or nasal cavity.
- consists of:
- hard palate: anterior, immobile
- soft palate: posterior, mobile, tip of uvula
What is the hard palate formed by?
- the palatine process of maxillae and horizontal process of palatine bones; it is arched
What are the muscles of the soft palate?
- also called velum palatinum
- tensor veli palatini
- tenses soft palate, opens pharyngotympanic tube, CN V3
- levator veli palatini
- elevates soft palate, CN X
Function and innervation of uvular, palatopharyngeus, and palatoglossus?
- Uvular elevates uvula, CN X
- Palatopharyngeus elevates pharynx, CN X
- Palatoglossus elevates tongu, CN X
What are the extrinsic muscles of tongue with function and innervation?
- all innervated by CN XII
- Styloglossus retracts and elevates tongu
- Genioglossus protrudes and depresses tongue
- Hypoglossus retracts and depresses tongu
What are the salivary glands and ducts innervated by?
- innervated by parasympathetic fibers
- from facial nerve: submandibular gland, sublingual gland
- from glossopharyngeal: parotid gland
