Neuroanatomy 2 Flashcards
What joins the bones of the base of the skull?
fibrous joints called sutures
What 3 distinct depressions can be found on the base of the skull when looking down from above?
3 cranial fossae
Anterior cranial fossa
Middle cranial fossa
Posterior cranial fossa
What are cranial foramina?
Small holes which allow nerves, arteries, veins to pass through the skull
In each cranial fossa
What bones make up the anterior cranial fossa?
Orbital part of the frontal bone
Cribriform plate and crista galli of the ethmoid bone
Lesser wings of the sphenoid bone
What foramen can be found in the anterior cranial fossa?
The cribriform plate - transmits olfactory fibres
What bones is the middle cranial fossa made up of?
Petrous and squamous parts of the temporal bone - inferior and medial part of the temporal bone, flat lateral part of the temporal bone respectively
Greater wing and body of the sphenoid bone - cont the pituitary fossa(sella turcica)
Where is the pituitary fossa? (sella turcica)
The body of the sphenoid bone in the middle cranial fossa in the base of the skull
What foramina are there on each side of the middle cranial fossa? [6]
optic canal - transmits optic nerve
superior orbital fissure - transmits several nerves to the orbital region
foramen rotundum - transmits maxillary branch of trigeminal nerve
foramen ovale - transmits mandibular branch of trigeminal nerve
foramen lacerum - internal carotid artery exits carotid canal here
foramen spinosum - transmits middle meningeal artery
Which nerves are transmitted by the superior orbital fissure to the orbital region?
Motor innervation
- oculomotor
- trochlear
- abducens
Sensory innervation
- ophthalmic branch of trigeminal nerve
Which foramen do the branches of the trigeminal nerve travel through?
Ophthalmic branch - superior orbital fissure
Maxillary branch - foramen rotundum
Mandibular branch - foramen ovale
What bones make up the posterior cranial fossa?
Which lobes rest in the anterior cranial fossa?
frontal lobes
Which lobes rest in the posterior cranial fossa?
What bones make up the posterior cranial fossa?
Occipital lobe
Cerebellum
Brainstem
Occipital bone
Petrous part of the temporal bone (most anterior border)
Which lobes rest in the middle cranial fossa?
Temporal lobes
What foramina are located in the posterior cranial fossa? [4]
Internal auditory meatus - transmits VIII and VII into inner ear cavity
Jugular foramen - transmits nerves IX,X,XI and internal jugular vein
Hypoglossal canal - transmits nerve XII
Foramen magnum - central singular foramen allows central nervous system fibres to become spinal cord
What passes through the cribriform plate?
Olfactory fibres
What is transmitted by the optic canal?
Optic nerve into the bony orbit
What is transmitted by the superior orbital fissure?
Oculomotor (III)
Trochlear (IV)
Abducens (VI)
Ophthalmic branch of the trigeminal (V)
What is transmitted by the foramen rotundum?
Maxillary branch of trigeminal nerve (V)
What is transmitted by the foramen ovale?
Mandibular branch of the trigeminal nerve (V)
What is transmitted by the foramen lacerum in the brain?
Internal carotid artery exits the carotid canal through this foramen to enter the skull
What is transmitted by the foramen spinosum in the skull?
Middle meningeal artery
What is transmitted by the internal auditory meatus in the skull?
Vestibulocochlear (VIII)
Facial (VII)
into the inner ear cavity
What is transmitted by the jugular foramen in the skull?
Glossopharyngeal (IX)
Vagus (X)
Acessory (XI)
Internal jugular vein
What is transmitted by the hypoglossal canal in the skull?
Hypoglossal nerve (IX)
What is transmitted by the foramen magnum in the skull?
Single central foramen - spinal cord
What are consequences of a traumatic head injury?
Brain damage
Damage structures passing through the foramina
Damage dura and meninges, CSF could leak out - clear liquid from nose or ears is suspicious
Significant bleeding
What is the pterion?
Area of the skull often referred to as the temple
Shallow depression where 4 bones meet:
Frontal, temporal, sphenoid, parietal
Weakest part of the skull and prone to fracture if struck
Middle meningeal artery lies behind it - can extradural haemorrhage if this happens
What is craniosyntosis?
When sutures of the skull fuse together too early
Skull becomes misshapen as brain continues to grow
What are burr holes?
What is a craniotomy?
Small holes (10-15mm diameter) drilled into the skull to relieve pressure quickly/immediately
Allows brain to expand or used to drain fluid
Craniotomy is a circular piece of the skull is removed to perform brain surgery, can be replaced later or have a prosthetic implant to close it
Describe the two bony orbits?
Shaped like cones
Broad opening at the front
Taper to a narrow part at the back
Formed from…
Frontal, sphenoid, zygomatic, maxillary bones
Also smaller ethmoid and lacrimal bones
What structures can be found within the orbits?
Eye - at front of the orbit
Extraocular muscles - 6 move the eye, 7th retracts upper eyelid
Nerves - II for vision, III,IV,VI control muscles, ophthalmic branch for sensation
Fat
Lacrimal gland - in the superior and lateral part of the orbit - produces tears to lubricate