Skull and Cranial Nerves Flashcards
what is the difference between the head skeleton and the skull?
skull: braincase + face, ear ossicles
head skeleton: skull + mandible + hyoid apparatus + cartilages of ear, nose, larynx
what are the functions of the skull?
housing/protecting brain and special senses
gateway for respiratory and digestive tracts
base of attachment of muscles of mastication
mediating behaviours (facial expressions, vocalizations)
how is the skull divided?
into braincase and face
how do skull bones develop?
intramembranous growth
how do skull bones fuse generally?
into sutures (syndesmoses)
how are skull bones separated in an immature skull?
by narrow strips of fibrous tissue
most skull bones form by intramembranous growth. what are the exceptions?
ethmoid, sphenoid, occipital formed by endochondral bone growth
what is the neurocranium?
cranial vault - formed by intramembranous bone growth
what is the chondrocranium?
cranial base - formed by endochondral bone growth
what 3 paired bones form the vault of the braincase?
frontals, parietals, temporals
what are hte 4 unpaired bones that form the midline in the braincase?
ethmoid, sphenoid, occipital, intraparietal
label bones 6, 7, 9
6 = frontals
7 = parietals
9 = temporals
label bones 12+14, 8, and the arrow
12+14 = sphenoid
8 = occipital
arrow: intraparietal
label A, B, and C
A: rostral fossa
B: middle fossa
C: caudal fossa
what are the 3 fossae of the cranial cavity?
rostral, middle, caudal
what is the rostral fossa bounded by?
sphenoid floor, ethmoid wall, frontal roof
what does the rostral fossa house?
frontal and olfactory lobes
what bounds the middle fossa?
sphenoid floor, frontal/parietal wall and roof
what is housed in the middle fossa?
temporal and parietal lobes
what bounds the caudal fossa?
temporal and occipital floor & wall, parietal roof
what does the caudal fossa house?
hindbrain and brainstem
what are sinuses?
cavities between inner and outer layers of specific bones
what are the facial bones?
bones that support the face, teeth, nasal and oral cavities
label bones 10, 3, 4, 1, 2, 11, 13
10 = zygomatics
3 = maxillae
4 = lacrimals
1 = nasals
2 = incisives
11 = palatines
13 = pterygoids
label bone A (in blue)
vomer
how is the mandible linked?
fused at mandibular symphysis
what are the nasal cavities? what are their bony margins?
facial part of respiratory passages
margins: nasal aperture to chonanae
what the conchae/turbinates?
scroll-like paper-thin bones in nasal cavity
what is the function of conchae?
covered with mucosa, slow down, warm, and clense inspired air
what defines the meatuses?
conchae
what bone is the cribiform plate part of?
ethmoid
where is the synovial joint in the braincase?
temporomandibular joint (TMJ)
what type of joint is the temporomandibular joint (TMJ)?
synovial, condylar
where is the synchondrosis in the skull?
mandibular symphysis
what does the foramen magnum do?
allows brain stem and spinal cord to exit brain
label bones 15 and 21
15 = quadrate
21 = articular
what do the quadrate and articular become in mammals?
middle ear bones
what is a sclerotic ring?
ring of bone inside the orbit in birds
what is the incisive called in birds?
premaxilla
how many occipital condyles do birds have?
1
what are the cranial nerves?
nerves that originate in the brain
cranial continuation of spinal nerve tracts
what are the nerves that come out of the dorsal root?
somatic and visceral afferent
what are the nerves that come out of the ventral root?
somatic and visceral efferent
what do the somatic afferent nerves do?
exteroreceptive (pain, heat, touch), proprioception, vision, hearing, balance
what do visceral afferent nerves do?
enteroreception (stretch, chemical), smell, taste
what do visceral efferent nerves do?
smooth muscle (autonomic nervous sytem)
what do somatic efferent nerves do?
striated muscle
true or false: CN with more than 1 functional component arise from 1 nucleus
false. they arise from more than 1 nucleus
true or false: some nuclei give rise to more than 1 cranial nerve
true
what is the order of the cranial nerves?
I - olfactory
II - optic
III - oculomotor
IV - trochlear
V - trigeminal
VI - abducent
VII - facial
VIII - vestibulocochlear
IX - glossopharyngeal
X - vagus
XI - accessory
XII - hypoglossal
list the functional components of the cranial nerves (sensory, motor, both)
I - sensory
II - sensory
III - motor
IV - motor
V - both
VI - motor
VII - both
VIII - sensory
IX - both
X - both
XI - motor
XII - motor
list the functional compontents of the cranial nerves (visceral, somatic, both)
I - visceral
II - somatic
III - both
IV - somatic
V - somatic
VI - somatic
VII - both
VIII - somatic
IX - both
X - both
XI - somatic
XII - somatic
describe the path the olfactory nerve (I) takes from the brain to where it innervates
olfactory bulbs –> cribiform plate –> nasal epithelium in ethmoid conchae
what is the function of the olfactory nerve (I)?
sense of olfaction (smell)
describe the path the optic nerve (II) takes from the brain to where it innervates
diencephalon –> optic chiasm –> optic canal –> retina
what does the optic nerve (II) do?
sense of vision
describe the path the vestibulocochlear nerve (VIII) takes from the brain to where it innervates
lateral medulla –> internal acoustic meatus –> inner ear (vestibule and cochlea)
describe the path the trochlear nerve (IV) takes from the brain to where it innervates
midbrain –> orbital fissure/foramen orbitorotundum –> dorsal oblique muscle of eye
what is the function of the vestibulocochlear nerve (VIII)?
hearing and balance
what is the function of the trochlear nerve (IV)?
movement of eye
describe the path the abducent nerve (VI) takes from the brain to where it innervates
medulla –> orbital fissure/foramen orbitorotundum –> lateral rectus and retractor bulbi muscles in eye
what is the function of the abducent nerve (VI)?
movement of eye
what is the difference between the orbital fissure or foramen orbitorotundum?
pig and cow have a fused orbital fissure and round window –> foramen orbitorotundum
dogs and horses have two separate holes
describe the path the hypoglossal nerve (XII) takes from the brain to where it innervates
medulla –> hypoglossal canal –> tongue muscles
what is the function of the hypoglossal nerve (XII)?
movement of tongue
describe the path the oculomotor nerve (III) takes from the brain to where it innervates
crus cerebri –> orbital fissure –> dorsal rectus, medial rectus, ventral rectus, ventral oblique, levator palpebri, ciliary muscles, pupil constrictors in eye
what is the function of the oculomotor nerve (III)?
movemnet of eye, control of light entering eye
what are the 3 branches of the trigeminal nerve (V) called?
opthalmic, maxillary, mandibular
describe the path the opthalmic trigeminal nerve (V) takes from the brain to where it innervates
pons –> orbital fissure –> orbit/frontal area
describe the path the maxillary trigeminal nerve (V) takes from the brain to where it innervates
pons –> round window –> infraorbital, nasal, maxillary areas
describe the path the mandibular trigeminal nerve (V) takes from the brain to where it innervates
pons –> oval window –> mastication muscles, mandibular area
what is the function of the trigeminal nerve (V)?
external eyeball, skin of skull, vibrissae and upper teeth, jaw, skin of lower face, teeth of lower jaw, mouth, tongue
describe the path the facial nerve (VII) takes from the brain to where it innervates
medulla –> internal autitory meatus –> stylomastoid foramen –> lacrimal glands and paranasal sinuses, rostral 2/3 taste buds, stapedius muscle, muscles of facial expression, oropharynx
what is the function of the facial nerve (VII)?
jaw and face muscles, taste in rostral 2/3 of tongue
describe the path the glossopharyngeal nerve (IX) takes from the brain to where it innervates
medulla –> jugular foramen –> pharynx, parotid gland, caudal 1/3 of tongue –> pharyngeal plexus
what is the function of the glossopharyngeal nerve (IX)?
sense of gustation in caudal 1/3 of tongue, sensations of throat region
describe the path the vagus nerve (X) takes from the brain to where it innervates
medulla –> jugular foramen –> upper body from neck down to abdomen
what is the function of the vagus nerve (V)?
contraction and sensation of upper body region
describe the path the accessory nerve (XI) takes from the brain to where it innervates
spinal cord –> foramen magnum –> jugular foramen –> brachiocephalicus, omotransversarius, dorsal trap, sternocephalicus
what is the function of the accessory nerve (XI)?
movement of neck and pharynx
label this image
A: frontal
B: nasal
C:incisive
D: maxilla
E: lacrimal
F: zygomatic
G: parietal
H: temporal
what bone is this?
mandible
label these structures
A: occipital
B: interparietal bone
label these bones
A: sphenoid
B: vomer
C: pterygoid
D: palatine
what is the blue circle? what bones make it up?
zygomatic process
zygomatic bone and temporal bone
what is the structure in the blue circle?
sagittal crest
label the arrows and circles
A: mandibular fossa
B: mastoid process
C: tympanic bulla
D: external auditory meatus
red circle: squamous part
green circle: petrous part
pink circle: tympanic part
label these structures
A: foramen magnum
B: nuchal crest
C: hypoglossal canal
D: occipital condyle
E: paracondylar process
F: external occipital protuberance
label these structures
A: retroarticular process
B: tympanic bulla
C: paraoccipital process
D: occipital condyle
what are structures A and B?
A: jugular foramen
B: internal auditory meatus
what is this structure?
infraorbital foramen
what structure is this?
cribiform plate
label these structures
A: optic canal
B: orbital fissure
C: rostral alar canal
what is structure A?
A: caudal alar canal
label structures A, B, and the orange pipe cleaner
A: oval window
B: round window
orange pipe cleaner: alar canal
