CNs, Facial Muscles, Muscles Of Mastication

Question 1

CNs

Answer 1

-Olfactory - S
-Optic - S
-Oculomotor - M
-Trochlear - M
-Trigeminal - B
-Abducens - M
-Facial - B
-Auditory (Vesitbulocochlear) - S
-Glossopharyngeal - B
-Vagus - B
-Accessory - M
-Hypoglossal - M

Question 2

sensory vs motor

Answer 2

-sensory- nerve impulse from sensory receptors to brain ex. pressure, temperature, pain
-motor- from brain to body to accomplish action ex. movement of muscle, activation of gland

Question 3

visceral vs somatic sensory

Answer 3

-visceral- sensory innervation to viscera
-ex. stretch, pain, temp, chemical change, irritation of viscera
-SPECIAL- taste
-somatic- sensory innervation to outer body
-ex. touch, pain, pressure, vibration, temp in skin, body wall, limbs
-SPECIAL- hearing, equilibrium, vision smell

Question 4

visceral vs somatic motor

Answer 4

-visceral- motor innervation in viscera + glands -> innervation smooth + cardiac muscle, glands
-somatic- motor innervation of skeletal -> innervation of skeletal muscles (except pharyngeal arch muscle)

Question 5

cranial nerve function

Answer 5

-olfactory- smell
-optic- vision
-oculomotor- extrinsic eye muscles
-trochlear- extrinsic eye muscles
- V - trigeminal
- V1 - opthalmic- sensory- cornea, nasal mucosa, face skin
- V2 - maxillary- sensory- skin of face, oral cavity, teeth
- V3 - Mandibular - motor -> muscles of mastication / sensory- face skin, teeth, tongue (general)
-abducens- eye abduction
-facial- sensory - part of tongue (taste) / motor- muscles of facial expression
-vestibulocochlear- hearing, equilibrium
-glossopharyngeal- motor- stylopharyngeus muscles / sensory- tongue (general and taste), pharynx
-vagus- motor- pharynx, larynx / sensory- pharynx, larynx, abdominal organs
-accessory- trapezius, sternocleidomastoid
-hypoglossal- tongue muscles

Question 6

CN1: Olfactory

Answer 6

-attaches to cerebrum
-many nerve endings from olfactory bulb
-pass through olfactory foramina in cribriform plate of ethmoid bone to receptors in roof of nasal cavity
-sensory for smell

Question 7

CN2: Optic

Answer 7

-attaches to diencephalon
-enters orbit through optic canal
-sensory for vision

Question 8

CN3: oculomotor

Answer 8

-attaches to midbrain
-enters orbit through superior orbital fissure
-motor to 3 of 4 extrinsic muscles of eye -> Superior, inferior, and medial rectus muscles and inferior oblique muscle
-parasympathetic to muscles controlling pupil and lens of eye

Question 9

CN4: trochlear

Answer 9

-attaches to midbrain
-enters orbit through superior orbital fissure
-motor to superior oblique muscles of eye

Question 10

CNV: trigemianl: V1 ophthalmic

Answer 10

-first branch of trigeminal
-attaches to pons
-enters orbit through superior orbital fissure -> Exits orbit through supraorbital foramen/notch
-sensory- cornea, nasal mucosa, face skin

Question 11

CNV- trigeminal- V2 maxillary

Answer 11

-second branch of trigeminal
-attaches to pons
-passes through foramen rotundum, inferior orbital fissure and out the infraorbital foramen
-sensory- skin of face, oral cavity, teeth

Question 12

CNV- trigeminal: V3 mandibular

Answer 12

-third branch of trigeminal
-attaches to pons
-exits cranial cavity through foramen ovale -> into mandibular foramen and out mental foramen
-motor- muscles of mastication
-sensory- face skin, teeth, anterior 2/3 tongue (general)

Question 13

CN6: abducens

Answer 13

-attaches to pons
-enters orbit through superior orbital fissure
-motor to lateral rectus muscle of eye

Question 14

CN7: facial

Answer 14

-attaches to pons
-exits cranial cavity -> through internal acoustic meatus, -> exits skull through stylomastoid foramen
-sensory to anterior 2/3 tongue for taste
-motor to muscles of facial expression
-parasympathetic to mandibular and sublingual glands, lacrimal gland

Question 15

CN8: vestibulocochlear

Answer 15

-attaches to pons
-enters inner ear through internal acoustic meatus
-sensory to organs of hearing and equilibrium

Question 16

CN9: glossopharyngeal

Answer 16

-attaches to medulla oblongata
-exits cranial cavity through jugular foramen
-motor to stylopharyngeus muscle
-sensory to posterior 1/3 tongue (general and taste), pharynx
-parasympathetic to parotid gland

Question 17

CN10: vagus

Answer 17

-attaches to medulla oblongata
-exits cranial cavity through jugular foramen
-aka wanderer
-motor to pharynx, larynx
-sensory to pharynx, larynx, abdominal organs
-parasympathetic to thoracic and abdominal organs

Question 18

CN11: accessory

Answer 18

-attaches to medulla oblongata
-exits cranial cavity through jugular foramen
-joined by spinal segment passing through foramen magnum
-motor to trapezius and sternocleidomastoid muscles

Question 19

CN12: hypoglossal

Answer 19

-attaches to medulla oblongata
-exits cranial cavity through hypoglossal canal
-motor to tongue muscles

Question 20

functions of CN summary

Answer 20

-purely sensory- 1, 2, 8
-primarily motor- 3, 4, 6, 11, 12
-mixed- 5, 7, 9, 10
-parasympathetic fibers- 3, 7, 9, 10 (division of autonomic NS = visceral motor)

Question 21

parasympathetic CNs

Answer 21

-CN 3 = Oculomotor- Contracts Iris (controls pupil) and Ciliary Muscle (controls lens)
-CN 7 = Facial - Innervates Salivary glands (mandibular & sublingual) and Lacrimal gland
-CN 9 = Glossopharyngeal- innervates Parotid Salivary gland
-CN 10 = Vagus- Innervates thoracic & abdominal viscera

Question 22

muscles of mastication

Answer 22

-Embryology of muscles of mastication:
-Mesoderm of 1st branchial arch and are supplied by mandibular artery
-Posterior belly of digastric arises from 2nd branchial arch and is supplied by the facial nerve

Question 23

primary and secondary muscles of mastication

Answer 23

-PRIMARY:
-lateral pterygoid
-medial ptyerygoid
-masseter
-temporalis

-SECONDARY:
-digastric
-geniohyoid
-myelohyoid

Question 24

disorders of mastication

Answer 24

-Myofascial pain
-Myositis
-Myospasm
-Myofibrotic contraction
-Centrally medicated myalgia/chronic myositis
-Local myalgia

Question 25

contents of temporal fossa

Answer 25

-1-Temporalis muscle.
-2-Temporal fascia -> covers temporalis muscle, attached above to superior temporal line and below to upper border of zygomatic arch
-3-Deep temporal nerves : from the anterior division of mandibular N., emerge from upper border of lateral pterygoid, enter the deep surface of temporalis
-4- Auriculotemporal nerve: arise from the posterior division of mandibular N -> emerges from upper border of parotid gland, lies behind superficial temporal artery & TMJ, in front of the auricle -> supplies skin of auricle , ext.auditory meatus and the scalp over the temporal region.
-5-Superficial temporal artery: it is a terminal branch of ext.carotid artery.
It emerges from upper border of parotid gland, behind T.M.J. -> crosses root of zygomatic arch in front of auriculo-temporal N. & auricle, here its pulsation can be easily felt

Question 26

contents of infratemporal fossa

Answer 26

-Lateral & medial pterygoid muscles (muscles of mastication)
-Branches of the Mandibular N.
-Otic ganglion
-Chorda tympani
-Maxillary artery
-Pterygoid venous plexus

Question 27

lateral pterygoid

Answer 27

-Origin: upper head -> from the infratemporal surface of the greater wing of sphenoid // Lower head -> from the lateral surface of lateral pterygoid plate
-Insertion- neck of mandible (pterygoid fovea) & articular disc of T.M.J.
-N.supply: anterior division of mandibular N.
-Action: -1-Pulls the neck of mandible forward with the articular disc to depress mandible during opening of mouth. -2-Acting with medial pterygoid of the same side during movement of chewing. -3-Acting with medial pterygoid to protrude the mandible

Question 28

temporal and infratemporal fossae

Answer 28

-Temporal fossa :extends above by the sup. temporal line and below by zygomatic arch.
-Infratemporal fossa : lies beneath the base of the skull, between the pharynx (medially) & ramus of mandible (laterally). or the space lying below the temporal fossa and behind the maxilla

Question 29

tempromandibular joint (TMJ)

Answer 29

-Articulation : between the articular tubercle & mandibular fossa of temporal bone, and the head of mandible (condyloid process).
-Type : condyloid synovial joint.
-Capsule :it surrounds the joint.
-Synovial membrane -> lines the capsule in upper & lower cavities.

Question 30

ligaments of tempermandibular joint

Answer 30

-Lateral temporomandibular ligament : lies on the lateral side of joint ,between the tubercle and lateral surface of the neck of mandible.
-Sphenomandibular ligament : lies on the medial side of the joint ,it connects the spine of sphenoid to the lingula of mandibular foramen.
-Stylomandibular ligament behind & medial .to the joint. it is a band of thickened deep cervical fascia, from apex of styloid process to angle of mandibule

Question 31

intracapsular articular disc

Answer 31

-It is a plate of fibro-cartilage, it divides the joint into upper & lower cavities.
-It is attached in front to the tendon of lat. pterygoid , and by fibrous bands to head of mandible.
-Its upper surface is concavo-convex to fit the articular tubercle & mandibular fossa , while its lower surface is concave to fit the head of mandible

Question 32

relation of temporomandibular joint (TMJ)

Answer 32

-Anteriorly : mandibular notch and masseteric N. & artery (structures passing through mandibular notch).
-Posteriorly : ext.auditory meatus, glenoid process of parotid gland., auriculotemporal N., & superficial temporal artery.
-Laterally :parotid gland, fascia & skin.
-Medially : maxillary vessels

Question 33

clinical significance of TMJ

Answer 33

-The great strength of the Lat.TM ligament prevents head of mandible from passing backward to cause fracture of the tympanic plate in case of severe blow on the chin.
-The articular disc may be partially detached causing noisy & audible click, during movements of the joint.

Question 34

dislocation of TMJ

Answer 34

-Sometimes occurs when the mandible is depressed.
-In case of minor blow on chin or sudden contraction of lateral pterygoids as in yawning, leads to pull the head of mandible & articular disc forward beyond the summit of tubercle.
-Reduction of dislocation: by pressing the thumbs downward on the lower molar teeth and pushing the jaw backward