Skull and the cranial cavity Flashcards
List the 5 layers of the scalp
Skin Dense connective tissue Epicranial Aponeurosis Loose connective tissue Periosteum
What does the scalp extend over?
Neurocranium
What innervates the scalp?
Trigeminal nerves
Spinal cutaneous nerves
How many bones comprise the skull?
22
Give the other name for the facial skeleton
Viscerocranium
List the 8 neurocranium bones
Occipital 2 Temporal 2 Parietal Frontal Sphenoid Ethmoid
List the 14 viscerocranium bones
2 nasal conchae 2 nasal bones 2 maxilla 2 palatine bones 2 zygomatic bones 2 lacrimal bones Vomer Mandible
What is the purpose of foramina?
Allow for nerves and blood vessels to enter and leave the cranial cavity.
List the 3 cranial fossa the base of the skull is divided into
Anterior
Middle
Posterior
List the foramina found in the anterior cranial fossa
Foramen caecum
Cribriform plate
List the foramina found in the middle cranial fossa
Superior orbital fissure Optic canal Foramen rotundum Foramen ovale Foramen spinosum Foramen lacerum
List the foramina found in the posterior cranial fossa
Internal acoustic meatus
Jugular foramen
Foramen magnum
Hypoglossal canal
List the 3 layers of the meninges starting from outermost layer
Dura mater
Arachnoid mater
Pia mater
What is the function of the meninges?
Protection
Support network for blood vessels
Form a fluid filled cavity to cushion and nourish the brain
What are the 2 layers of the dura mater and where are they found?
Meningeal layer- surrounds brain and spinal cord
Endosteal layer- lines the skull
What is the nervous supply of the dura mater?
CN 5
CN 10
CN 1-3
Sympathetic
What is the blood supply to the dura mater?
Middle meningeal artery
What is the purpose of the folds and reflections of the meningeal layer of the dura mater?
To prevent or restrict movement of the brain
What does the falx cerebri do?
Separates cerebral hemispheres
What does the tentorium cerebelli do?
Separates the cerebral hemispheres and cerebellar hemispheres
What does the falx cerebelli do?
Separates cerebellar hemispheres
What is the anatomical basis of a headache?
The dura is sensitive to stretching
Damage to the middle meningeal artery causes what?
Extradural (Epidural) haematoma
What causes tentorial herniation?
Space occupying lesion causes herniation of the temporal lobe
What is special in terms of vascularisation of the arachnoid mater?
Avascular
Describe the arachnoid mater
Thin avascular layer between pia and dura
Loosely applied layer with projections
Where do all structures passing to and from the brain exit or enter?
Subarachnoid space
What is contained in the subarachnoid space?
Cerebral spinal fluid
Where is CSF made?
Choroid plexus in brain ventricles
What is the importance of CSF in the subarachnoid space?
Provides buoyancy to the brain protecting it from mechanical forces
What is pia mater?
Very delicate vascular membrane (nourish)
Where is the pia mater found?
Closely innervates brain following gyri and sulci
Covers cerebral arteries entering the brain
List the 3 layers of the spinal cord meninges
Dura mater
Arachnoid mater
Pia mater
What is leptomeningitis and why is this dangerous?
Inflammation and infection of the pia and arachnoid mater. May enter subarachnoid space and cause septicemia.
Where do dural sinuses sit?
Behind the dural fold
What drains into the dural sinuses?
Drained blood and CSF from the brain via cerebral veins.
Communicates with the veins of the skull and scalp
Describe the structure of the dural sinuses
Thick walled endothelium
No valves
No smooth muscle
Where do the dural sinuses drain?
Internal jugular vein
What 2 arteries is the brain supplied by?
Internal carotid artery
Vertebral artery
What do the branches anastomose to form?
Circle of willis
What are the 2 terminal branches found within the skull?
The anterior cerebral artery
The middle cerebral artery
Where do vertebral arteries enter?
Pass within cervical vertebrae and enter foramen magnum
What do vertebral arteries unite to form?
Basilar artery
What does the anterior cerebral artery supply?
The medial and superior surfaces of the brain
Frontal pole
What does the middle cerebral artery supply?
The lateral surfaces
The temporal pole
What does the posterior cerebral artery supply?
The inferior surfaces of the brain
The occipital pole
Why does a stroke cause neurological deficit?
No anastomosis of cerebral arteries once inside brain
What is a stroke caused by?
Embolism in the cerebral artery
When will mixing in the posterior communicating artery occur?
If there is an occlusion which disrupts the pressure in the vertebral and internal carotid artery.
Blood passes back and forth across posterior communicating artery to compensate
