BS - Brain, Skull & Cranial Nerves - Week 9 Flashcards
Define fissure.
Narrow slit between parts of bone through which vessels pass.
Define foramen.
Hole-like opening through which vessels pass.
What is an incomplete foramen called?
Notch.
Define sulcus.
Furrow along a surface which accommodates a vessel, also grooves in the brain cortex.
Define meatus.
Tulublar opening: also canal.
Define fossa.
Shallow depression.
Define tubercle.
Small rounded projection.
Define sinus.
Air or venous cavities.
How many bones are in the skull, and what kind of joints are they connected by? Are they mobile?
Consists of 22 bones united by immobile joints called sutures.
How many cranial and facial bones are there in the skull?
8 cranial bones, and 14 facial bones.
Name the bones of the cranium.
Frontal Ethmoid Sphenoid Parietal x2 Temporal x2 Occipital
Name the facial bones.
Zygomatic x2 Maxilla x2 Nasal x2 Lacrimal x2 Inferior conchae x2 Palatine x2 Vomer Mandible
Name the four sutures.
Coronal - most anterior
Sagittal - between the coronal and lamboid
Lamboid - most posterior, looks like a γ
Name the 3 fossa of the cranium.
Anterior cranial fossa
Middle cranial fossa
Posterior cranial fossa
What is the anterior border of the posterior cranial fossa?
The petrous temporal bone.
What composes the floor of the posterior cranial fossa?
Basilar, condylar, and squamous occipital bones.
What composes the lateral anterior border of the floor of the posterior cranial fossa?
Mastoid process.
Describe the floor of the posterior cranial fossa.
- Basilar occipital bone, forming just anterior to the foramen magnum.
- Condylar occipital bone, forming just latero-posterior to the basilar occipital bone.
- Squamous occipital bone - found posterior to the foramen magnum on either side, flat smooth region of bone where the cerebellum sits.
What forms the roof of the posterior cranial fossa?
A fold of dura called the tentorium cerebelli
Where can the hypoglossal canal be found?
Almost within the foramen magnum, just lateral to the jugular foramen.
Where can the jugular foramen be found?
Just posterior to the internal acoustic meatus.
What forms the anterior border of the middle cranial fossa?
The lesser wing of sphenoid
What 3 structures form the floor of the middle cranial fossa?
Temporal bone
Greater wing of sphenoid
Parietal bone
What forms the posterior margin of the middle cranial fossa?
Petrous temporal bone
Which bone contacts every other bone in the cranium?
Sphenoid bone
Where can the ethmoid bone be found?
Between the frontal bone, and the sphenoid bone, where the cribriform plate for the olfactory nerve sits.
Where can the parietal bone be found?
Lateral to the temporal bone.
Define the optic groove, and where the optic canals are located.
A groove found between the two optic canals, the optic groove.
Optic canals are found on the sphenoid bone, just superior to the sella turcica and lateral to the lesser wing of sphenoid.
Where is the superior orbital fissure?
Inferior to the lesser wing of sphenoid.
Where is the foramen rotundum?
First small foramen found laterally to the sella turcica. It is the most anterior, just posterior to the superior orbital fissure.
Where is the foramen ovale?
The second foramen found laterally to the sella turcica. It is the largest foramen lateral to the sella turcica, and found between the foramen rotundum (superiorly), and the foramen spinosum (inferiorly).
Where is the foramen spinosum?
The third small foramen found laterally to the sella turcica. It is found inferior and lateral to the foramen ovale.
Where is the foramen lacerum?
Large irregular shaped foramen found inferior and medial to the foramen ovale.
What passes through the foramen lacerum in adults?
Nothing, its filled with cartilage.
What passes through the foramen rotundum?
Maxillary branch (2st division) of the trigeminal nerve (CNV)
What passes through the foramen ovale?
Mandibular branch (3rd division) of the trigeminal nerve (CNV)
What passes through the foramen spinosum?
Middle meningeal artery
What passes above the foramen lacerum?
Internal carotid artery
Viewing the floor of the cranium inferiorly, where is the carotid foramen?
Anterior to the jugular foramen, and inferior to the foramen spinosum.
What two bones form the infraorbital margin, and which is medial/lateral?
Zygomatic bone laterally, maxilla medially.
What bone forms the supraorbital margin?
Frontal bone.
What 2 bones forms the lateral orbital margin?
- Zygomatic process of the frontal bone
- Frontal process of the zygomatic bone
What 2 bones forms the medial orbital margin?
- Maxillary process of the frontal bone
- Frontal process of the maxilla
What can be found superior to the orbit?
Frontal sinus within the frontal bone.
What two bones form the roof of the orbit?
Frontal bone
Lesser wing of sphenoid
What three bones form the floor of the orbit? Name them anterior to posterior.
Zygomatic bone
Orbital plate of the maxilla
Palatine bone
What is the thickest part of the orbit?
The lateral wall.
What two bones form the lateral wall of the orbit? Name them anterior to posterior.
Zygomatic bone
Greater wing of sphenoid
What two bones form the medial wall of the orbit? Name them anterior to posterior.
Frontal process of the maxilla
Lacrimal bone
Orbital plate of ethmoid
Body of sphenoid
Which bone is the optical canal found in?
Lesser wing of sphenoid
What is the superior orbital fissure found between?
The lesser and greater wings of sphenoid.
What is the inferior orbital fissure found between?
The greater wing of sphenoid and maxilla
Where is the infraorbital foramen found? What passes through it?
Found inferior to the orbital cavity, on the maxilla.
Infraorbital nerve and vessels pass here.
Where is the zygomaticofacial foramen, and what passes through it?
Found lateral to the orbital cavity, close to the inferior border.
The zygomaticofacial nerve passes here.
Where is the supraorbital notch? What passes through it?
Found superior to the orbital cavity, and the supraorbital margin. The supraorbital nerve and vessels pass here.
What is the cerebral cortex?
The outer section of the brain.
Where is the corpus callosum?
It is the inner part of the brain that joins the two hemispheres together.
Where is the fornix of the brain found?
Within the middle of the corpus callosum, inferiorly.
Where is the thalamus found?
Inferior to the thalamus.
Where is the hypothalamus found?
Anteroinferior to the thalamus, and superior to the pineal gland.
Where is the midbrain?
Inferior to the thalamus, the superior most end of the brainstem.
Where is the pons located?
Found directly inferior to the midbrain. Looks like a giant belly.
Where is the medulla oblongata?
Directly inferior to the pons.
Where is the spinal cord?
Directly infeiror to the medulla.
Define the mesencephalon.
Midbrain
What 3 structures form the brainstem?
Midbrain/mesencephalon, pons, and medulla oblongata
Where is the cerebellum found?
Posterior to the brainstem.
Define the diencephalon.
The thalamus, hypothalamus, and pineal gland.
What four structures form the cerebrum?
Cerebral cortex, basal ganglia, amygdala, and the hippocampus.
Consider a cross section of the brain, and of the spinal cord. How are grey and white matter arranged?
Brain - white matter on the inside, grey matter on the outside.
Spinal cord - grey matter on the inside, white matter on the outside.
What does white matter consist of?
Axons and oligodendrocytes
What does grey matter consist of?
Neuronal bodies and unmyelinated fibres
How many layers of cells forms the grey matter in the cerebral cortex?
6 neuronal cell body layers.
Do subcortical structures have grey matter?
Yes, nuclei.
Name the four lobes of the brain, anterior to posterior.
Frontal
Parietal (superior)
Temporal (inferior)
Occipital
Where are the superior and inferior colliculi found?
On the midbrain anteriorly, just inferior to the thalamus, and on either side of the pineal gland.
Where are the nuclei of the cranial nerves?
All in the brainstem, except the olfactory (CNI) and the optic nerves (CNII).
Name the 6 cranial nerves that are important for vision.
II III IV V VI VII
In what direction do the cranial nerves exit the brainstem?
All nerves exit anteriorly, except for the trochlear nerve, which exits posteriorly.
Define the medial longitudinal fasiculus, and where it is found.
It is the main central connection for CNIII, IV, and VI
It is found beginning at the midbrain, and passing inferiorly to the medulla oblongata.
Which nerves and vessels pass through the wall of the cavernous sinus?
CNIII, IV, and V
Which nerves and vessels pass through the middle of the cavernous sinus?
CNVI and the internal carotid artery.
Which branches of the trigeminal nerve passes through the superior orbital fissure (3)?
Lacrimal
Frontal
Nasal
All three are from the ophthalmic (1st) division of the trigeminal nerve
What kind of blood supply system is provided to the brain? What supplies blood anteriorly vs posteriorly.
A dual blood supply:
Posterior - vertebral artery
Anterior - Common carotid artery
Define the circle of willis.
An anastamotic system that sits at the base of the brain, creating a redundancy or vascular backup.
Describe what vessels form the circle of willis, and their path/branching (7).
Internal carotid artery
ICA enters bilaterally, and splits into the anterior cerebral artery and posterior communicating artery.
Anteriorly the anterior cerebral artery merges.
Posteriorly the posterior communicating artery merges with other vessels to form the posterior cerebral artery.
The two posterior cerebral arteries merge to form the basilar artery.
The basilar artery splits posteriorly to form the two vertebral arteries.
After the anterior cerebral artery splits off the internal carotid artery, it (the ICA) becomes the middle cerebral artery.
Define what regions of the brain are supplied by the anterior, middle, and posterior cerebral arteries.
The lateral regions of the brain are supplied by the middle cerebral artery, including the middle and inferior border of the frontal/parietal lobes, the superior and middle border of the temporal lobe, and the anterior region of the occipital lobe.
The posterior cerebral artery supplies the inferior temporal lobe, the posterior occipital lobe, and the posterior margin of the parietal lobe.
The anterior cerebral artery supplies the anterior region of the parietal lobe, the superior, and anterior regions of the frontal lobe.
Define a border zone infart, and describe why it can occur.
Anastamoses between the three cerebral arteries occurs at their ends, and when blood pressure is reduced, the area is poorly supplied, and susceptible to ischaemia.
