Osteology, Radiology, Meninges, Dural Folds and Venous Sinuses Flashcards
(38 cards)
What’s the difference between neuro and viscerocranium?
Neurocranium surrounds the brain and viscerocranium the face.
He skull is made of 22 bones with different features. What do the following mean: fossae, canal, foramina and fissures?
Fossae are shallow depressions/ hollows (skull has ant, middle and post). A canal is a bony tunnel. Foramina are round and fissures are narrow holes.
8 bones make up the neurocranium to encase and protect the brain, with the calvaria (skull cap), cranial floor and cranial cavity. How do these bones develop?
Cal aria bones begin through intramembranous ossification and the floor by endochondrial ossification.
There are 14 bones in the viscerocranium (which develop mostly from the pharyngeal arches), making up the facial skeleton and jaw, what do they surround?
The oral cavity, pharynx and upper respiratory tract.
Why does the cranial floor need holes in it?
For cranial nerve communication with the face and neck and blood vessels need to pass in and out.
Internally the neurocranium has 3 fossae on the cranial floor to seat different parts of the brain (and associated structures), what features might be seen in them?
Each has a set of foramina, some have fissures and canals for communication and the bone is grooved by the location of sural venous sinuses.
Describe and explain the function of the trilaminar arrangement of the calvaria.
Compact bone makes the outer table, then spongy for diploeic cavity and then compact inner table. This arrangement confers strength without adding significant weight.
The edge of neurocranium bones are serrated at sutures, so there is not slippage or movement. Name 3 important duties in the skull.
Sagittarius, coronal, lambdoid.
When do eps growth of skull sutures stop?
Growth is stopped around puberty and the obliterated inside to outside.
What is the importance of suture lines in the boundaries of Cephalohaematoma?
This bleed between the periosteum and skull cannot pass intracranially over over suture lines, as the periosteum covers the outer table and strongly adheres at suture lines, continuing through to the periosteum on the inner table.
What are fontanelles and their purpose?
Large areas of unossified membranous gaps between flat bones of the calvaria in an infant, that allow for skull shape/size alteration during birth and permit growth of the infant brain.
When do fontanelles fuse in a healthy individual and what is Early sutures of fontanelles and sutures known as?
Anterior fusion occurs at 1.5-2 years and posterior fusion 1-3 months.
Craniosyntosis.
What can examination of the fontanelles tell you?
Inspection and gentle palpation of anterior fontanelles is used to access intracranial pressure and state of hydration (in context) - healthy is slightly convex.
What type of imaging is used in a ‘bone window’ to see the suture lines and layers of the bone at an axial view?
CT scan
Significant force/ trauma is needed for a skull, is the same force needed the whole way around it?
No, the skull has variable thickness and so resistance to breaking.
What is the main concern with a skull fracture and how can this be viewed?
Intracranial injury (skull doesn’t have to be fractured for it) of the brain, blood vessels or cranial nerves, so do a CT scan.
What are the 2 types of skull fracture and how do they differ structurally?
Linear fractures pass the full thickness through the skull, so are fairly straight and there’s no displacement.
Depressed fractures involve a segment displaced inwards.
What is a fracture involving the cranial base called and what may be associated?
Basilar skull fractures may have associated cranial nerve injury, CSF leakage and other signs (Racoon eyes or Battle sign-behind ear, also look in ear).
What is the Pterion and what type of haemorrhage can injury to this site cause?
The Pterion is where many bones meet at the side of the skull and where it is at its thinnest, so easiest to fracture. The (anterior branch of the) middle meningeal artery sits underneath it and bleeding of this can cause an extradural intracranial haemorrhage.
What will have if there is trauma to the supraorbital ridge and supracillary arch?
They are very tough, so likely that the skin will split.
Which bones are commonly fractured in the face?
Fracture of nasal bone, zygomatic bones and arch are common, as well as the mandible.
What are the meninges and their 3 layers?
Membranous layers that surround and protect the brain.
Pia - microscopically thin and adherent to brain surface, Arachnoid - soft, translucent membrane, Dura - tough, fibrous membrane.
Where in relation to the meninges, do blood vessels and CSF run?
Blood vessels run in the subdural space and CSF with cerebral blood vessels Andre in the subarachnoid space.
The arachnoid layer does not dip into the ______, but does between the ______________. The dura is strongly adhered to the _______ ________.
Sulci
Hemispheres
Inner table