Cranial fossae Flashcards
What are the 3 types of cranial fossae and what bones make up their floors?
Anterior- frontal, ethmoid, sphenoid
middle- sphenoid and temporal
posterior-temporal and occipital
What fibres make up CN I (olfactory) and what foramen does it pass through?
- Special sensory
- cribiform plate
What fibres make up CN II (Optic) and what foramen does it pass through?
- special sensory
- optic canal
What fibres make up CN III (oculomotor) and what foramen does it pass through?
- MIXED- somatic motor and parasympathetic
- superior orbital fissure
What fibres make up CN IV (trochlear) and what foramen does it pass through?
- Somatic motor
- superior orbital fissure
What fibres make up CN V (trigeminal) and what foramen does it pass through?
- MIXED- somatic motor and somatic sensory
- Va- superior orbital fissure
- Vb- retundum
- Vc- ovale
What fibres make up CN VI (abducent) and what foramen does it pass through?
- somatic motor
- superior orbital fissure
What fibres make up CN VII (facial) and what foramen does it pass through?
- MIXED- somatic motor, somatic sensory, special sensory, parasympathetic
- internal acoustic meatus
What fibres make up CN VIII (vestibulochlear) and what foramen does it pass through?
- special sensory
- internal acoustic meatus
What fibres make up CN IX (glossopharyngeal) and what foramen does it pass through?
- MIXED- somatic motor, somatic sensory, special sensory, parasympathetic
- jugular foreman
What fibres make up CN X (vagus) and what foramen does it pass through?
- MIXED- somatic motor, somatic sensory, special sensory, parasympathetic
- jugular foramen
What fibres make up CN XI (spinal accessory) and what foramen does it pass through?
- somatic motor
- jugular foreman
What fibres make up CN XII (hypoglossal) and what foramen does it pass through?
- somatic motor
- hypoglossal canal
Describe the anatomy of CN I
- special sensory (sense of smell)
- origin- forebrain (cerebral hemispheres
- pass through cribriform plate
Describe the anatomy of CN II
-Special sensory ( sense of sight)
-origin- forebrain (diencephelon)
- 2 visual fields :
temporal and nasal
-where two optic nerves cross over is called optic chiasm
What are the 2 types of muscles in the iris?
- circular smooth muscle called sphincter papillae
- radial smooth muscle called dilator pupillae
How can CN II be clinically tested?
- pupillary light reflex
- tests sensory and motor function of eye
- dual response due to cross over at chiasma
Describe the anatomy of CN III
- origin - midbrain
- somatic motor to 4 skeletal ocular muscles and levator palpebral superioris
- parasympatheic to sphinctor pupillae
Describe the anatomy of CN IV
- origin- posterior aspect of midbrain
- somatic motor- superior oblique muscle
Describe the anatomy of CN VI
- origin- junction between pons and medualla
- somatic motor- lateral muscle
Describe the anatomy of CN V
- Va- sensory to upper face
- Vb- sensory to skin of midface
- Vc- sensory to most of lower face and motor to muscles of mastication , anterior belly of digastric, mylohyoid and 2 tensors
Where do all 3 sensory fibres from Va,b and c join together?
Trigeminal sensor ganglion
Where does the motor root of CN V lie and what foreman does it pass through?
Beneath the sensory ganglion and passes through foreman oval alongside sensory Vc
What foramen does the middle menial artery pass through
spinosum
How is the cavernous sinus formed?
When two layers of dura separate
What runs through the cavernous sinus?
internal carotid artery and CN VI
What runs through the dura?
CN III, IV, Va and Vb
Where do the greater and lesser petrosal nerves run?
Greater- behind Vc nerve
lesser- exit skull through foreman oval along with mandibular division of trigeminal nerve
Describe the motor innervation of the parotid gland in reference to pre and post ganglion fibres
Coming from glossopharyngeal nerve found in the tympanic plexus, into lesser petrosal branch that reaches the synapse of the otic ganglion. The post ganglionic parasympathetic travels in auriculotemporal nerve and is delivered to the the parotid gland