Cranial Fossa And Cranial Nerves Flashcards
What are the fossae within the skull
Anterior, middle and posterior
What is within the anterior fossa
Cribriform plate, crista galli and optic canal
What is within the middle fossa
Foramen rotundum, foramen ovale, foramen lacerum and foramen spinosum
What does the carotid canal contain
The internal carotid artery
What does the foramen spinosum contain
The middle meningeal artery
What does the posterior fossa contain
The groove for the sigmoid dural sinus, jugular foramen, hypoglossal canal and the foramen magnum
What are the cranial nerves
Olfactory, optic, occulomotor, trochlear, trigeminal, abducens, facial, vestibulocohlear, glossopharyngeal, vagus, accessory and hypoglossal
CN 1 Olfactory
Outgrowth of the telencephalon
Only sensory system that is not relayed through the thalamus
Path of the olfactory
The olfactory mucosa goes through the cribriform plate to synapse in the olfactory bulb
Where does the olfactory nerve run from/to
The olfactory tracts to the prepiriform area of amygdala
What is the prepiriform area of amygdala
Primary olfactory cortex
CN II Optic
Extension of the diencephalon
Where does the optic nerve run from/to
The retina through the optic canal, then forms a chiasm and joins the optic tract
What happens to the fibres of the optic nerve
90% - go to the lateral geniculate body of the thalamus and onto the striate area
10% - go to the medial root (non-genicular) to unconcious regulation
CN III Oculomotor
Come from the midbrain and enters the orbit
Provides somatic motor and parasympathetic innervation
What does the oculomotor nerve provide motor innervation to
Inferior oblique, superior rectus, middle rectus, inferior rectus and levator palpabrae
What does the occulomotor provide parasympathetic innervation to
Sphincter pupillae and ciliary body
What does the superior division of the oculomotor supply
Levator palpabrae and superior rectus
CN IV Trochlear
Comes from the midbrain
Only cranial nerve in which the fibres cross to the opposite side and the only cranial nerve from the posterior surface of the midbrain
Where does the oculomotor run from/to
The lateral wall of the cavernosous dural sinus and travels through the annular ring
Where does the trochlear run from/to
The lateral wall of the cavernous dural sinus and sits outside the annular ring
CN V Trigeminal
Originates from the pons
Forms a ganglion and divides into three divisions
What are the three divisions of the trigeminal
CN V1 - ophthalmic branch
CN V2 - maxillary branch
CN V3 - trigeminal branch
What does the ophthalmic branch enter
The orbit through the superior orbital fissue
Where does the maxillary enter
The pytergopalatine fossa through the foramen rotundum
Where does the trigeminal branch travel
Through the foramen ovale to the inferior surface of the base of the skull
What nerves allow the passage of parasympathetic fibres from other cranial nerves
The lacrimal, zygomatic, lingual and auriculotemporal
What does CN V1 provide
General sensory innervation for the eye, lacrimal gland, eyebrow, skin of the forehead and nose
Where does CN V1 run
In the lateral wall of the cavernous dural sinus
What does CN V2 provide
General sensory innervation to the skin of the cheek, lower lid, upper jaw and teeth, side of nose and the mucosa of the mouth
Where does CN V2 run
In the lateral wall of the cavernous dural venous sinus
What CN V3 provide
Sensory innervation to the ear canal, parotid gland, lower jaw and teeth
Motor innervation to the muscles of mastication, anterior belly of digastric, mylohyoid, tensor tympani and veli tensor palatine
CN VI Abducens
Originates from the pons
Long extradural pathway
Where does the abducens run from/to
It passes through the superior orbital fissue, the cavernous dural venous sinus and annular ring and enters the eye
What does abducens provide
Motor innervation to lateral rectus
CN VII Facial
Originates from the pons
Passes through the acoustic meatus
Where does abducens run from/to
The pons to the temporal bone
What are the branches of the abducens
Greater petrosal, stapedial and chorda tympani
What are the facial muscle branches from abducens
Temporal, zygomatic, buccal, mandibular and cervical posterior auricular
What does abducens provide
Motor innervation to the muscles of facial expression, stapedius, stylohyoid and the posterior belly of digastric
Where do the nerves that innervates the muscles of facial expression leave through
The stylomastoid foramen
CN VIII Vestibulocochlear
Special somatic efferent nerve
From the vestibule apparatus and auditory apparatus to the pons/medulla
What does the vestibular nerve provide
Innervation to the maculae of the utricle and saccule, and the cristae of ampulla of the semicircular ducts
What is the maculae of the saccule and utricle sensitive to
Linear acceleration and the pull of gravity relative to the position of the head
What is the cristae of ampulla in the semicircular ducts sensitive to
Rotational acceeration
What does the cochlear nerve provide
Innervation to the special organs. for the sense of hearing
CN XI Glossopharyngeal
Originates from the medulla oblongata
Passes through the jugular foramen
What does the glossopharyngeal provide
Parasympathetic innervation to the parotid, buccal and labial glands
Sensation of taste to the posterior 1/3rd of the tongue
Motor innervation to the pharyngeal plexus and stylopharyngeus
Sensory innervation to the posterior 1/3rd of the tongue, soft palate, pharynx, tympanic cavity and membrane, pharyngotympanic tube, external ear and auditory canal
CN X Vagus
Originates from the medulla oblongata
Passes through the jugular foramen
Distribution of the vagus nerve
Cranial, cervical, thoracic and abdominal
What does the vagus provide
Motor innervation to the pharyngeal plexus, soft palate and larynx
Parasympathetic innervation to the thoracic and abdominal viscera
Sensory innervation to the dura in the post-cranial fossa, ear, external auditory canal, lower pharynx, laryngeal mucosa, thoracic and abdominal viscera
What does the vagus provide in the aortic arch and para-aortic body
Aortic arch - pressure receptors
Para-aortic body - chemoreceptors
CN XI Accessory
Originates from the spinal cord
Enters the foramen magnum and the passes through the jugular foramen
What does the accessory nerve provide
Motor innervation to trapezius and sternocleidomastoid
CN XII Hypoglossal
Originates from the medulla oblongata, anterior to the olive
Passes through the hypoglossal canal
What does the hypoglossal nerve provide
Motor innervation to all the intrinsic and extrinsic muscle of the tongue bar palatoglossus
