Osteology Flashcards
How are bones o the skull divided?
Neurocranium
Viscerocranium
What is the neurocranium?
Calvaria - skul cap
Cranial floor
Cranial cavity
What is the role of the neurocranium?
Encase and protect the brain
How many bones make up the neurocranium?
8
How many bones make up the viscerocranium?
14
What is the viscerocranium?
The bones that make up the face and jaw
What bones make up the calvaria?
Frontal
Parietal
Occipital
Sphenoid
What are the sutures?
Tough fibrous joints between bones - where soft as an infant
What are the different sutures?
Coronal suture - between parietal bones and frontal bone
Sagittal suture - between parietal bones
Lambdoid suture - between parietal bones and occipital bone
What is the point between the coronal and sagittal sutures called?
Bregma
What is the point between the sagittal and lambdoid suture called?
Lambda
What are fontanelles?
Areas of membrane between bones in infants that allow the growth of the infant brain
When do the fontanelles fuse?
Anterior = 18 months - 2 years
Posterior = 1-3 months
What is the structure of the bone in the calvaria?
Trilaminar bone
- outer table = compact bone
- diploe = spongy bone
- inner table - compact bone
What is periosteum?
Covering of the surface of the outer and inner table of bones that is continuous through sutures
Where does the middle meningeal artery lie?
Between periosteum and inner table of bone
What is the clinical relevance of the periosteum?
Bleeds from middle meningeal artery strip away periosteum but are contained by sutures - gives the shape of extradural haemorrhages
What bones form the cranial floor?
Frontal Ethmoid Sphenoid Temporal Occipital
What are the areas of the cranial floor?
Anterior fossa
Middle fossa
Posterior fossa
What are the borders of the anterior fossa?
Anterior/lateral = frontal bone
Posterior/medial = limbus of sphenoid
Posterior/lateral = lesser wing of sphenoid
Floor = frontal + ethmoid + sphenoid
What is found in the anterior fossa?
Crista galli - attachment for falx cerebri
Cribiform plate - supports olfactory bulb
What are the borders of the middle fossa?
Anterior/lateral = lesser wing of sphenoid
Anterior/medial = limbus of sphenoid
Posterior/lateral = petrous part of temporal bone
Posterior/medial = dorsum sellae
What is found in the middle fossa?
Optic canal Superior orbital fissure Foramen rotundum Foramen ovale Foramen spinosum Foramen lacerum Carotid canal
What passes through the optic canal?
CNII - optic
Ophthalmic artery
What passes through the superior orbital fissure?
CNIII - oculomotor CN IV - trochlear CNVa - trigeminal CNVI - abducens Ophthalmic veins
What passes through foramen rotundum?
CNVb - trigeminal
Where does the foramen rotundum open into?
Pterygopalatine fossa
What passes through the foramen ovale?
CNVc - trigeminal
Where does the foramen ovale open into?
Infratemporal fossa
What passes through the foramen spinosum?
Middle meningeal artery
Middle meningeal vei
Where does the foramen spinosum open into?
Infratemporal fossa
What passes through foramen lacerum?
Filled with cartilage
What passes through the carotid canal?
Internal carotid
What are the borders of the posterior fossa?
Anterior/medial = dorsum sella
Anterior/lateral = petrous bone
Posterior = occipital bone
Floor = temporal + occipital
What is found in the posterior fossa?
Internal acoustic meatus
Hypoglossal canal
Jugular foramen
Foramen magnum
What passes through the internal acoustic meatus?
CNVII - facial
CNVIII - vestibulocohlear
What passes through the hypoglossal canal?
CNXII - hypoglossal
What passes though the jugular foramen?
CNIX - glossopharyngeal
CNX - vagus
Internal jugular vein
What passes through the foramen magnum?
Medulla of brainstem
Meninges
Vertebral arteries
Spinal accessory nerve
What is the pterion?
Thinnest area of skull
What is the clinical relevance of the pterion?
Easy to fracture
Underlying anterior branch of the middle meningeal artery can cause an extradural haemorrhage
What are the signs of skull base fractures?
Raccoon eyes
Battle sign - bruising behind ears
Haemotypanum
CSF ottorhea/rhinorrhea
What bones make up the viscerocranium?
Nasal Zygomatic Lacrimal Maxilla Mandible