Cranial nerves Flashcards
CN1
N. olfactoria
- develops in foetus as the process of the telencephalon.
- starts from radia/*pars olfactoria (mucous membrane in nasal cavity) where small *fila olfactoria (15-20) pass through small openings on lamina gribrosa; *gribrae ethmoidales
to fossa cranii anterior *bulbus olfactorius
2nd order neurons start there and continue to *tractus olfactorius (in sulcus olfactorius)
> continues into *trigonum olfactorium and substantia perforata anterior and 3rd order neurons start.
The divide into
- stria olfactoria intermedia
- stria olfactoria lateralis
- -> continues into uncus (deep in temporal lobus) through primary olfactory are (BA34) nucleus amygloidea - stria olfactoria medialis
- area subcallosa (cortex)
Fornix - columnae, corpus, commisura, crura fornicis
- run to septal nuclei (limbic system - olfactory memory) - connect to amygdala
> through stria terminalis w/hippocampus
> through fornix with gyrus cinguli, thalamus and hypothalamus
CN2
N. opticus
- develops as a process of the diencephalon
- from retina: *discus opticus
> pass through *canalis opticus (w/a. opticus) to fossa cranii media - fibers from both eyes fuse at *chiasma opticus which liese in sulcus prechiasmaticus
- 50% of the fibers cross here
- continue as tractus opticus and turns arouns crus cerebri ending in corpus geniculatum laterale (hearing in mediale)
- then pass through *crus posterius capsula interna as *radiatio optica
- ends in visual cortex lying in sulcus calcarinus
they may also connect to
- nuclei of nervus oculomotorius
- Through intermediate neurons to stratum visium colliculi superioris (reflectory pathways: tractus tectospinalis etc)
CN3
N. oculomotor
- eye movement; mixed nerve: motor and PS
- 2 nuclei in mesencephalon
- emerge through fossa interpeduncularis
—> small radices from *sulcus nervi oculomotorii form the compact nerve (locates in sulcus cavernosus b. venous blood) b. Spehoid bone and DM - passes through fissura orbitalis superior
- divides into
1. ramus superior: M - nuclei nervi oculomotorii (in mesencephalon)
- supplies extraocular muscles (m. rectus superior and levator palpebrae superioris)
- ramus inferior: + PS fibers detach and join ganglion ciliare
- M: m. rectus inferior/medialis, m. obliquus inferior
PS (pre):
- nuclei accessorii n. oculomotorii (The Edinger–Westphal nucleus)
> cross mesenchephalon - emerge from fossa interpeduncularis
- leave the oculomotorii branch to form root for ganglion * radix parasympathica ganglii ciliaris
> ganglion ciliare –> postganglionic i: m. sphincter pupillae and m. ciliaris
CN4
N. trochlearis: M
- nucleus in mesenchephalon in fron of aqueductus cerebri and passes around, crosses the midline
- emerges on lamina tecti, escape below colliculus inferior
- curves around pedunculi cerebri / crus cerebri in cisternae ambiens
—> enters sinus cavernosus and through fissura orbitalis superior
- supplies m. oblique oculi superior (eye movement down laterally)
CN5
N. trigeminale
- 4 nuclei:
1. motorii n. trigeminale: above colliculus fascialis on top of eminentia medialis - for n. mandibulae
- sensorius/principalis n. trigemini
- laterally to motor in sulcus limitans - mesencephali n. trigemini
- above motor - spinalis n. trigemini
- the lowest
- mixed nerve M, S
- appears b. the pons and pedunculus cerebellaris medius
- splits into 3 parts after penetrating dura mater
- nervus ophthalmicus – V1
- nervus maxillaris – V2
- nervus mandibularis – V3
- Radix sensoria
- ganglion trigeminale ( Gasser’s ganglion in cavum trigeminale (DM cavity) in impressio trigeminalis on the petrous part of temporal bone - Radix motoria
- inferiorly to sensory
CN6
N. Abducens
- m. rectus oculi laterali ABDUCTION
nucleus on colliculus fascialis
> cross BS
- come out b. pons and pyramis from sulcus bulbopontinus
- passes through cisterna pontis
- in composition of sinus cavernosus laterally (w/3,45a) to arteria carotis interna
- leaves the sinus at processus clinoideus anterior
- enters through fissura orbitalis superior
CN7
N. facialis
- mixed: M, S, PS
nucleuii:
1. motorii n. facialis
2. PS: salivatorius superioris: above stria medullaris
3. sensory: nucleii tractus solitarii : below
- emerges b. pons and oliva; joins and pass through sulcus bulbopontinus b. 6th and 8th CN
- out from truncus cerebri - close to angulus bulbopontinus
- runs forward to the internal acoustic porus
- passes through the internal acoustic meatus (with CN7) to canalis nervi facialis then:
The PS (visceromotor) and S fibres are joined into n. intermedius:
- At the first curve of canalis nervi facialis the nerve has ganglion geniculi
> below divides into two branches:
1. n. petrosus major contains preganglionic PS fibres; it leaves canalis facialis through hiatus canalis nervi petrosi majoris, enters the middle cranial fossa, pierces cartilage of foramen lacerum and then through canalis pterygoideus reaches fossa pterygopalatina
- forms PS root for the PS ganglion – ganglion pterygopalatinum
— the postganglionic connects to n. maxillaris and innervates lacrimal, nasal, and salivatory/palatine glands (on palatinum)
- chorda tympani contains sensory and preganglionic PS fibres
- leaves canalis facialis through canaliculus chordae tympani
- passes through the tympanic cavity, lies b. malleus and incus, then through fissura petrotympanica leaves the cavity
- Further travels together with n. lingualis
- -> Sensory fibres (SVA) continue to the tongue to supply papillae fungiformes et papillae foliatae and give taste sensation from anterior 2/3 of the tongue * taste pathway
- Preganglionic ps fibres run to the PS ganglion – ganglion submandibulare and form the PS root for the ganglion - N. Stapedius
- smallest muscle
- arises at the descending part the facial canal, runs to the tympanic cavity and supplies m. stapedius
somatomotor:
- exit from the canal through foramen stylomastoideum
- neck muscles are derivates of the 2nd visceral arch
- goes to the substance of the parotid gland and forms plexus intraparotideus
- -> arise branches:
1. rr. temporales - run obliquely upward to supply facial muscles around the auricle, venter frontalis m. occipitofrontalis/orbicularis oculi/corrugator supercilii/procerus
- rr. zygomatici
- run obliquely forward to supply m. orbicularis oculi, m. zygomatici - rr. buccales
- run forward and supply m. zygomatici/levator labii superioris/levator anguli oris/risorius/buccinator/orbicularis oris/nasalis - r. marginalis mandibularis
- runs along basis mandibulae and supplies m. depressor
labii inferioris/depressor anguli oris/mentalis - r. colli
- runs downward and supplies platysma
side branches:
- starts from n. facialis below foramen stylomastoideum:
1. n. auricularis posterior
- starts from n. facialis below foramen stylomastoideum:
- divides into two branches:
a. r. auricularis supplies facial muscles of the ear
b. r. occipitalis supplies venter occipitalis musculi occipitofrontalis
- r. digastricus
- supplies venter posterior musculi digastrici - r. stylohyoideus
- supplies musculus stylohyoideus
CN8
N. vestibulocochlearis
- S
- 2 portions which join in meatus acusticus internus
- b. pons and MO
- -> in cisternae pontis
- -> after crossing reaches BS on pontocerebellar angle (laterally to sulcus)
- n. cochlearis
- formation of the auditory pathway
- 1st neurons in ganglion cochleare/spirale
–> dendrites in cortin’s organ
- in BS synapses with nuclei nervi cochlearis (close to lateral angle on fossa rhomboidea)
–> anteriorly cross the midline and form corpus trapezoideum
–> switch to opposite side to superior olivary complex nucleii
+ nucleus cochlearis dorsalis (4:10 video)
–> lemniscus lateralis under trigonum leminsci > 2 choices:
a. –> colliculus inferior through its brachium to corpus geniculatum mediale
–> capsula interna BA41/42
b. colliculus inferios to stratum griseum colliculi superioris
–> tractus tectospinalis (motor neurons of ventral horns in medulla spinalis) - n. vestibularis
- balance pathway;
- 1st neurons in ganglion vestibulare
–> dendrites in macula utrcile/saccule and semicircular ducts ampullas
- in BS synaps nucleii n. vestibularis (in area vestibularis)
–> tractus vestibulospinalis
–> inferior olivary nucleus
–> tractus vestibulo-olivaris
–> tractus vestibulocerebellaris
—> to thalamus VPL
+through fasciculus longitudinalis medialis communicates with other cranial nerves
CN9
N. glossopharyngeal - mixed: S, M, PS nucleii a. tractus solitarii (S) below fossa rhomboidea b. ambiquus c. salivatorius inferior (PS)
- truncus cerebri at the level of MO (sulcus retroolivaris) comes out as multiple small radices (on top of CN10) through foramen jugulare
=> vagus group (9-11)
Ganglion superius glossopharyngei (a)
Ganglion inferius glossopharyngei (a)
- nerve descends behind a. carotis interna, then between a./v. jugularis interna
- -> runs to tongues and gives off terminal branch:
r. linguales - supply the mucous of radix lingue till epiglottis (except vallecula epiglottica) and papillae vallatae
- -> terminal branches by GVA innervate mucosa of radix linguae and by SVA give taste sensation from the P 1/3 tongue
Side branches:
- n. tympanicus
- contains S and preganglionic PS fibres
- arises at the level of ganglion inferius, passes into canaliculus tympanicus and forms – plexus tympanicus – in the tympanic cavity
- Through canaliculi caroticotympanici (from canalis caroticus) to the plexus also join sympathetic fibres – nn. caroticotympanici – from the sympathetic plexus n. caroticus internus
- The tympanic plexus supplies the mucous membrane of the tympanic cavity, auditory tube and ear–filled mastoid cells
- terminal part is n. petrosus minor PS
- -> contains preganglionic PS fibres, leaves the tympanic cavity through hiatus canalis nervi petrosi minoris –> enters the middle cranial fossa, then goes through foramen ovale and forms PS root for PS ganglion – ganglion oticum (to parotid gland) - r. musculi stylopharyngei
- motor branch
- supplies m. stylopharyngeus - rr. pharyngei
- S branches
- reach the pharynx and together with the branches of CN10 and S fibres of the sympathetic trunk form plexus pharyngeus
- supply the mucous membrane of the palate and upper part of the pharynx
- m. Constrictor superior - rr. tonsillares
- S fibres to supply tonsilla palatina, arcus palatoglossus and arcus palatopharyngeus
+ rami lingualis: dorsal linguae
- r. sinus carotici
- descends to the baroreceptors of sinus caroticus and the chemoreceptors of glomus caroticum to participate in the regulation of the BP
CN10
N. vagus
- mixed: S, M, PS
- emerges on MO sulcus retroolivaris –> foramen jugulare
- above and below
i. ganglion superius
ii. ganglion inferius - -> synapse in nucleus tractus solitarii (S)
- -> between them joins r. internus of the CN11 to supply larynx musculi
- descends along the lateral side of the neck in the carotid sheath -> enters the thoracic cavity through apertura thoracis superior (S, PS)
- > posteriorly on esophagus - plexus oesaphageus - mucous membrane and SMfibers of esophagus in 2 trunks:
1. truncus vagalis anterior : rr. Cardici; curvatura minor; anteriorly. - reach GB and liver
2. truncus vagalis posterior - posterior gaster, rr. Renalis
- -> pass through diaphragm: form plexus coeliacus : kidneys, 2/3 ureter, spleen, pancreas, jejunum, ileum till half of the colon transversum, testis epididymis and ovarium
4 parts:
- cranial
- cervical
- thoracic
- abdominal
Other nuclei
- dorsalis nervi vagi (on trigonum; PS)
- ambiquus
CN11
N. accessorius - 2 motor nuclei
nucleus ambiquus –> radix cranialis in sulcus retroolivaris
nucleus nervi accessorii –> radix spinalis in sulcus posterolateralis on SC
-> enters the cranial cavity via foramen magnum and join with radix cranialis to form a single trunk of the nerve.
–> through foramen jugulare w/CN9-10 (vena jugularis interna posteriorly)
–> at basis cranii :
ramus externus: m. sternocleidomastoideus, m. trapezius
Ramus internus: joins CN10 (ramus pharyngeus and nervus laryngeus reccurens)–> muscles in pharynx, larynx and palatine (except m. stylopharyngeus/ tensor veli palatini)
CN12
N. hypoglossus
- muscles of the tongue
nucleus nervi hypoglossi on trigonum nervi hypoglossi
–> sulcus anterolateralis. –> radices join to form nerve which pass dura mater close to foramen magnum
–> pass through canalis nervi hypoglossi to basis cranii externa
–> turns around the main BV and lies laterally a. carotis interna and externa : runs between arteria carotis interna and vena jugularis interna,
–> passes through trigonum submandibulare on the external surface of musculus hyoglossus,
reaches the tongue and terminates as:
- *rami linguales to supply the muscles of the tongue.
- The other fibres travel via the hypoglossal nerve to supply musculus geniohyoideus and musculus thyrohyoideus
** join motor fibres of the ventral branches of the 1st and 2nd cervical spinal nerves via radix superior join the ansa cervicalis (plexus cervicalis).
Ganglion ciliare
- just behind the eye in the posterior orbit
- anteriorly to fissura orbitalis superior
- between m. rectus lateralis and the optic nerve
- d = 1–2 mm
parasympathetic root
- nucleus accessorius nervi oculomotorii
- fissura orbitalis superior in content of CN3
- via r. inferior n. oculomotorii
- supply m. sphincter pupillae and m. ciliaris
sympathetic root --> ganglion cervicale superius - n. caroticus internus -> along the BV enter the orbit - innervate m. dilatator pupillae and the smooth muscles of blood vessels
sensory root
- radix sensoria ganglii ciliaris of nervus nasociliaris (CN5)
- innervate the fibrous (sclera) and vascular (choroid) coats of the eyeball
gives off branches – nn. ciliares breves
Ganglion pterygopalatinum
- lies in fossa pterygopalatina: anteriorly to the anterior opening of canalis pterygoideus and inferior to n. maxillaris
- largest of the PS ganglia and is about 3 mm long
parasympathetic root
- arise in nucleus salivatorius superior
- n. petrosus major (CN 7) and through canalis pterygoideus –> some become n.zygomaticus
- > join n.lacrimalis
- supply glandulae palatinae, glandulae nasales, glands of nasopharynx and glandula lacrimalis;
- Some of the postganglionic PS fibres become components of n. zygomaticus
sensory root
- formed by radix sensoria ganglii pterygopalatini of n. maxillaris (CN5)
- innervate the mucosa of palate, nasal cavity and nasopharynx
sympathetic root
- ganglion cervicale superius
- via n. caroticus internus along the BV
- > through canalis pterygoideus as n. petrosus profundus
- n. petrosus major and n. petrosus profundus within the pterygoid canal form n. canalis pterygoidei
- innervate smooth muscles of the BV
The PS fibres (n. petrosus major/zygomaticus) and sympathetic fibres (n. petrosus profundus) enter branches of the maxillary nerve (below) and reach along them mucosa of the palate, mucosa of the nasal cavity, mucosa of the nasopharynx
– n. palatinus major; descends in canalis palatinus major
and through foramen palatinum majus enters oral cavity to supply mucosa of palatum durum and glandulae palatinae
–> arise rr. nasales posteriores inferiores to mucosa of nasal cavity
– nn. palatini minores - descend in foramina palatina minora, reach the soft palate, innervate it and mucosa of tonsilla palatina
- rr. nasales posteriores superiores laterales et rami nasales posteriores superiores
mediales from fossa pterygopalatina through foramen sphenopalatinum enter the nasal cavity to supply it.
The largest of the nasal branches is – n. nasopalatinus; it runs obliquely downward and forward along septum nasi and then through canalis incisivus enters the oral cavity to supply anterior part of the hard palate
• n. pharyngeus – a small branch, arising from the posterior part of the pterygopalatine ganglion; it passes backward and is distributed to mucosa of the nasopharynx, behind the auditory tube
Ganglion submandibulare
- n. lingualis
- sensory root for parasympathetic ganglion – radix sensoria ganglii submandibularis –
to ganglion submandibulare - chorda tympani
- Preganglionic ps fibres run to the PS ganglion – ganglion submandibulare and form the PS root for the ganglion.
- small and fusiform in shape
- situated above the submandibular gland on the hyoglossus muscle, near the posterior border of the mylohyoid muscle
parasympathetic root
- arise in nucleus salivatorius superior
- travel within chorda tympani (CN7)
- > enter cavitas tympani
- > leave it via fissura petrotympanica
- -> fossa infratemporalis join to n. lingualis
- -> reach the ganglion to synapse with the PS cells
sympathetic root
- ganglion cervicale superius
- > via n. carotici externi along a. facialis
sensory root
- formed by radix sensoria ganglii submandibularris of n. lingualis (CN5)
- Ganglion gives off branches that supply sublingual and submandibular glands
Ganglion oticum
n. pterygoideus medialis (CN5c) – contains motor fibers, goes through ganglion oticum
(provides physical support for the ganglion only)
n. auricolotemporalis (5c)
- rami parotidei – to glandula parotis; they receive postganglionic PS fibres and
postganglionic symphatetic fibers from ganglion oticum
n. tympanicus (CN9)
- terminal part is n. petrosus minor; contains preganglionic PS fibres
- > leaves the tympanic cavity through hiatus canalis n. petrosi minoris
- > enters the middle cranial fossa
- > then goes through foramen lacerum and forms PS root for PS ganglion – ganglion oticum
- located immediately below foramen ovale in fossa infratemporalis on the medial surface of the mandibular nerve
parasympathetic root
- arise in nucleus salivatorius inferiorior
- n. tympanicus –> n. petrosus minor (CN9)
sympathetic root
- > ganglion cervicale superius
- via n. carotici externi along a. meningea media go through
sensory root
- formed by radix sensoria ganglii otici of n. mandibularis (CN5)
- -> gives off branches that join n. auriculotemporalis (r. parotidei) to supply the parotid gland
- There are more branches from the otic ganglion that supply also mucosa of the cheeks, the lips, the fauces and the root of the tongue.
DORSAL RAMI OF CERVICAL NERVES
- thinner than the ventral rami, except the first two
- The first three
1. n. suboccipitalis - dorsal ramus of C1
- mainly motor fibres; a few sensory fibres of the nerve supply art. atlantoocipitalis and art. atlantoaxialis
- moves posteriorly b. the occipital bone and the 1st cervical vertebra, is located on arcus posterior atlantis and lies in sulcus a. vertebralis below a. vertebralis
- -> goes through the triangle bordered by m. rectus capitis posterior major/obliquus capitis inferior/obliquus capitis superior
- -> divides into branches to supply above-mentioned muscles as well as m. rectus capitis posterior minor / semispinalis capitis / longissimus capitis
- n. occipitalis major
- dorsal ramus of C2
- major dorsal ramus of the spinal nerves and contains mainly sensory fibres
- passes between arcus posterior atlantis and axis
- -> curves lower margin of
m. obliquus capitis inferior, pierces tendons of m. semispinalis capitis and m. trapezius and branches in subcutaneous tissue to supply skin of the medial occipital region
- forms communicating branches to the dorsal rami of C1 and C3 as well as communicates with n. occipitalis minor of plexus cervicalis
- accompanied by a. occipitalis - n. occipitalis tertius
- the dorsal ramus of C3
- supplies the skin of occipital region at protuberantia occipitalis externa
The others dorsal rami of spinal cervical nerves become smaller in size into lower direction and supply the deep muscles and the skin at the posterior part of the neck.
–> Each dorsal ramus divides into the ramus medialis et ramus lateralis
Mixed branch of cervical nerves
Nn. phrenicus
- M, S and PS sympathetic fibres (from ganglion cervicale medium et ganglion cervicale inferius)
- descends along m. scalenus anterior, through apertura
thoracis superior enters the thoracic cavity between v./a. subclavia
–> descends in mediastinum superius and then in mediastinum medium b. pleura mediastinalis and pericardium fibrosum
- runs together with a./v. pericardiacophrenica
–> descend in front of radix pulmonis and reach the diaphragm
** dexter descends along vena cava superior and through foramen venae cavae enters the abdominal cavity
** sinister enters the abdominal cavity between pars costalis of the muscular part of the diaphragm and centrum tendineum
In the abdominal cavity give off branches
1. rr. phrenicoabdominales
- S and sympathetic fibers innervate peritoneum
parietale in the diaphtagmatic region and participate in formation of plexus coeliacus
- The sensory fibres supply the
- pericardium
- mediastinal
- diaphragmatic parts of the parietal pleura
- the thymus
- Motor fibres supply the diaphragm
Sensory branch of cervical nerves
- appear at the posterior border of m. sternocleidomastoideus
or the nerve point of the neck, also known as Erb’s (german neurologist W.H. Erb) point - located approximately at the junction of the upper and middle
thirds of this muscle - From here, n. accessorius courses through the posterior
triangle of the neck to enter the anterior border of m. trapezius
Sensory branches pierce lamina superficialis of the cervical fascia and distrubutes in the skin
They are:
1. n. occipitalis minor (C2)
- appears at the middle part
of m. sternocleidomastoideus, ascends along its posterior border
- supplies the skin of the occipital region and posterior part of the
auricle
- connects with n. occipitalis major posteriorly and with n. auricularis magnus anteriorly
- n. auricularis magnus (C2, C3)
- ascends along the surface of m. sternocleidomastoideus together with v. jugularis externa and divides into:
a. r. posterior – supplies the skin of posterior par of the auricle and the skin of external auditory tube
b. r. anterior – supplies the skin at the angle of mandible - n. transversus colli (C2, C3)
- runs anteriorly, crosses m. sternocleidomastoideus
- passes on its external surface forward below platysma
- Then the nerve divides in 2 groups of branches:
• r. inferiores – pierce platysma and innervate the skin at trigonum colli anterior region,
• r. superiores – innervate the skin at trigonum submandibulare and connects with ramus colli of plexus intraparotideus - nn. supraclaviculares (C3, C4)
- pass downward over the external surface of m. sternocleidomastoideus and divide in 3 groups of branches:
a. rr. supraclaviculares mediales
• rr. supraclaviculares intermedii
• rr. supraclaviculares laterales
- supply the skin at trigonum colli laterale region, the skin
of the anterior thoracic wall to level of the 3rd rib, the skin of the upper and posterior shoulder region
