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
