Lecture 4.1 - The Skull and Overview of Cranial Nerves Flashcards

1
Q

What is the neurocranium?

A
  • houses brain
    • calvaria (skullcap)
    • cranial base (basicranium)
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2
Q

What is the viscerocranium?

A
  • facial bones that form:
    • orbits
    • nasal cavities
    • upper jaw
    • lower jaw (mandible)
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3
Q

What are the bones of the neurocranium and their location?

A
  • frontal (forehead)
  • parietal (2)
  • temporal (2)
    • mastoid process, styloid process, external acoustic meatus
  • occipital (back of head)
    • external occipital protuberance
  • sphenoid (butterfly)
  • ethmoid
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4
Q

What are the sutures of the neurocranium and which bones do they split?

A
  • Coronal: frontal and parietal
  • Lambdoid: parietal and occipital
  • Sagittal: R & L parietal
  • Squamous: parietal and temporal
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5
Q

What are the intersections of the cranial sutures?

A
  • Bregma: sagittal and coronal
  • Lambda: lambdoid and sagittal
  • Pterion: frontal, parietal, temporal, sphenoid
  • Asterion: parietal, occipital, temporal
  • Nasion: frontal and nasal bones
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6
Q

What occurs if the pterion is fractured?

A

Fracture to pterioni may tear the middle meningeal artery leading to an epidural hematoma

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7
Q

Where are the Glabella? Vertex? Inion?

A
  • Glabella: most anterior part of forehead
  • Vertex: superiormost post of neurocranum
  • Inion: most prominent point of external occipital protuberance
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8
Q

What bones make up the anterior fossa?

A
  • frontal bone
  • ethmoid bone
  • part of sphenoid bone (lesser wing)
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9
Q

What bones make up the middle fossa?

A
Sphenoid (greater wing/body)
Temporal bone (squamous and petrous part)
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10
Q

What bones make up the posterior fossa?

A
Temporal bone (petrous part)
Occipital bone
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11
Q

What holes are in the anterior fossa?

A

cribriform plate (ethmoid)

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12
Q

What holes are in the middle fossa?

A

All sphenoid

  • optic foramen
  • superior orbital fissure
  • foramen rotundum/ovale/spinosum/lacerum
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13
Q

What holes are in the posterior fossa?

A
  • internal acoustic meatus (temporal)
  • jugular foramen (between temporal and occipital)
  • hypoglossal canal (occipital)
  • foramen magnum (occipital)
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14
Q

What are the characteristics for the sphenoid bone?

A
  • it is a key in cranial skeleton
  • it articulates with 8 bones
  • has a central body, 2 wings laterally and 2 processes inferiorly
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15
Q

Where is the pituitary gland?

A

within the hypophysis in the sella turcica (body of sphenoid)

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16
Q

What are the bones of the viscerocranium?

A
  • lacrimal (2)
  • nasal (2)
  • zygomatic (2)
  • palatin (2)
  • inferior nasal conchae (2)
  • mandible
  • vomer
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17
Q

What bones form the orbit wall?

A
  • frontal bone
  • ethmoid bone
  • lacrimal
  • maxilla
  • palatine
  • zygomatic
  • sphenoid (greater/lesser wing)
  • superior/inferior orbital fissure
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18
Q

What bones form the nasal cavity?

A
  • nasal
  • maxillae
  • inferior nasal conchae
  • ethmoid (middle/superior nasal conchae and perpendicular plate)
  • vomer
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19
Q

What are the other important holes in the face?

A
  • Supraorbital notch/foramen (frontal): V1 trigeminal exits (ophthalmic nerve) supplying forehead sensory
  • Infraorbital foramen (maxilla): V2 trigeminal exits supplying mid face sensory
  • Mental foramen (mandible): V3 trigeminal supplying mandible sensory
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20
Q

What are cranial nerves?

A
  • nerves originating from brain or brainstem and exiting through foramina or fissures in the cranium
  • 12 pairs (CN1 - XII - anterior to posterior)
21
Q

What do cranial nerves variously carry nerve fibers for?

A
  • somatic motor (movement of eyes, mastication, deglutition, respiration, vocalization, facial expression)
  • general sensory (pain, pressure, temperature) to tissues
  • special sensory (olfaction, vision, gustation, audition, equilibrium)
  • parasympathetic motor (to lacrimal, salivary, and mucous glands and smooth muscles of eye)
22
Q

Olfactory Nerves (CN, Function, Innervation, Exit)

A

CN I
F: special sensory - smell
I: olfactory epithelium of superior nasal cavity
E: cribriform plate of ethmoid

23
Q

Optic Nerves (CN, Function, Innervation, Exit)

A

CN II
F: special sensory - vision
I: retina of the eye
E: optic foramen (sphenoid bone)

24
Q

What are the visual fields of retina?

A
  • optic nerve of each eye: temporal field, nasal fidl
  • optic chiasm: decussation of temporal fields of view
  • optic tracts: left (information from R fields of both eyes), right (information from left fields of both eyes)
25
Q

What does defect of right optic nerve cause?

A

blindness of one eye (anopsia)

26
Q

What is does defect of optic chiasm cause?

A

loss of peripheral visual fields (bitemporal hemianopsia; “tunnel vision”

27
Q

What does defect at right optic tract cause?

A

loss of visual field on opposite side (homonymous hemianopsia)

28
Q

Oculomotor nerve (CN, Function, Innervation, Exit)

A

CN III
Function/Innervates:
- somatic motor:
– all eye muscles except superior oblique (CN IV) and lateral rectus (CN VI)
– levator palpebrae superioris (muscle that raises eyelids)
- parasympathetic - constriction of pupils; change shape of lens (accommodation)
Cranial Exit: superior orbital fissure of sphenoid

29
Q

What does complete paralysis of CN III cause?

A

leads to dilated pupils, ptosis (droopy eyelids), and inability to move eye upward, downward, and medially

30
Q

Trochlear Nerves (CN, Function, Innervation, Exit)

A

CN IV
F: somatic motor - eye movement
I: superior oblique muscles of the eye
E: superior orbital fissure of sphenoid

31
Q

What occurs when trochlear nerve is injured?

A

patient unable to look downward and inward; says “has difficulty walking downstairs”

32
Q

Abducent/Abducens Nerve (CN, Function, Innervation, Exit)

A

CN VI
F: somatic motor - eye movement
I: lateral rectus muscle
E: superior orbital fissure of sphenoid

33
Q

What occurs when abducent nerve is injured?

A

patient has medial strabismus (deviation); unable to abduct the eye

34
Q

What are the 3 division of Trigeminal nerve and its CN number?

A

CN V
V1 ophthalmic
V2 maxillary
V3 mandibular

35
Q

V1 Ophthalmic division of Trigeminal nerve (Function, Innervation, Exit)

A

F: general sensory
I: conjunctiva and cornea of eye, nasal cavity, skin of scalp, forehead, eyebrows, upper eyelid, and part of external nose
E: superior orbital fissure of sphenoid

36
Q

What branches of V1 are seen in orbit?

A

lacrimal nerve and frontal nerve (divides into supraorbital nerve and supratrochlear nerve)

37
Q

V2 Maxillary division of Trigeminal nerve (Function, Innervation, Exit)

A

F: general sensory
I: lower eyelid, upper lip, upper gums, upper teeth, cheek, palate, and pharynx
E: foramen rotundum (sphenoid)

38
Q

What are the important branches of V2?

A

superior alveolar nerve and infraorbital nerve

39
Q

V3 Mandibular division of Trigeminal nerve (Function, Innervation, Exit)

A

F: general sensory and somatic motor
Innervation:
- Sensory - skin over mandible, lower gums, lower teeth, lower lip, anterior 2/3 of tongue
- Motor - muscles of mastication (temporalis, masseter, medial/lateral pterygoids), anterior digastric and mylohyoid muscles, tensor veli palatini m.
E: foramen ovale (sphenoid)

40
Q

What are the important branches of V3?

A
lingual nerve (tongue)
inferior alveolar nerve (lower teeth/gums)
mental nerve (chin)
41
Q

Facial Nerves (CN, Function, Innervation, Exit)

A

CN VII
Function/Innervates:
- parasympathetic
– lacrimal glands (tears)
– mucous glands of nasal cavity, pharynx, and palate
– submandibular/sublingual salivary gland
- special sensory - taste receptors on anterior 2/3 of tongue
Cranial Exit:
- through the internal acoustic meatus (temporal bone)
- out of the stylomastoid foramen (temporal bone)

42
Q

Vestibulocochlear Nerves (CN, Function, Innervation, Exit)

A

CN VIII (Acousticovestibular)
F: special sensory - balance and hearing
I: Vestibule (receptors for motion and balance) and Cochlea (hearing receptors)
E: internal acoustic meatus of temporal bone

43
Q

How can Vestibulocochlear nerve be damaged? What are the symptoms?

A

Can be injured in fractures of middle cranial fossa

  • cochlear n. leads to tinnitus (ringing, buzzing) and deafness
  • vestibular n. - vertigo and nystagmus
44
Q

Glossopharyngeal nerve (CN, Function, Innervation, Exit)

A

CN IX
Function/Innervates:
- general sensory: posterior 1/3 of tongue, pharynx, palate, tonsil
- special sensory: posterior 1/3 of tongue (taste), carotid body (monitors blood oxygen levels), carotid sinus (monitors blood pressure)
- parasympathetics: parotid gland (salivary)
- somatic motor: stylopharyngeus m.
Cranial exit: jugular foramen

45
Q

Vagus Nerves (CN, Function, Innervation, Exit)

A

CB X
Function/Innervation:
- motor: muscles of pharynx, larynx, and palate (except tensor veli palatini)
- general sensory: pharynx, tongue
- special sensory: taste to area around epiglottis
- parasympathetics (and sensory): abdominal and thoracic viscera
Cranial exit: jugular foramen

46
Q

What cranial nerves are part of gag reflex?

A

Glossopharyngeal: sensory part of gag reflex
Vagus: motor part of gag reflex

47
Q

Spinal Accessory Nerve CN, Function, Innervation, Exit)

A

CN XI
F: motor
I: sternocleidomastoid m. and trapezius m.
E: jugular foramen

48
Q

Hypoglossal Nerve CN, Function, Innervation, Exit)

A

F: motor - tongue muscles
I: all muscles with “gloss” in name (except palatoglossus m.)
E: hypoglossal canal (occipital)

49
Q

Name all 12 cranial nerves

A
Olfactory
Optic
Oculomotor
Trochlear
Trigeminal
Abducent
Facial
Vestibulocochlear
Glossopharyngeal
Vagus
Accessory
Hypoglossal