Skull and Cranial NervesAnthony Pappas, Ph.D.LECOM Bradenton – MMS
Learning Objectives•Understand the anatomy of the bonescomprising the skull – viscerocranium andneurocranium•Understand the 12 cranial nerves, the type ofinformation each nerve carries and theirrelationship to the skull.•Be able to predict cranial nerve lesions basedon symptoms
The Human Skull•Most bones of the skull are joinedby interlocking fibrous sutures–Temporomandibular joint (TMJ)is a synovial joint–Sphenoid and occipital bonesbecome united by hyalinecartilage (synchondrosis)mandibletemporal bonesutures
The Human Skull•Sutures form the fibrous jointsconnecting the bones of the skull•Obliteration of the sutures beginsinternally (30 - 40 yr) and endsexternally (~50 yr)
Sutures – Lateral viewcoronallambdoidsquamoussphenoparietalparietomastoidoccipitomastoid
Sutures – Posterior viewlambdoidsagittaloccipitomastoid
Sutures – Superior viewlambdoidcoronalsagittal
Craniometric points•Bregma – intersection betweenthe coronal and sagittal sutures•Lambda – intersection betweenthe sagittal and lambdoid sutures•Pterion – intersection betweenthe frontal, parietal, sphenoid andtemporal bonesFSTP
Clinical Note – Epidural hematoma•Fracture of the pterion can causea life-threatening intra-cranialhemorrhage calledepiduralhematoma.•The bleed is due to rupture of theanterior branch of the middlemeningeal artery•Blood pools within the epiduralspace (i.e., between dura andcalvaria) causing a dangerousincrease in intra-cranial pressure
Clinical Note – Epidural hematoma•Fracture of the pterion can causea life-threatening intra-cranialhemorrhage calledepiduralhematoma.•The bleed is due to rupture of theanterior branch of the middlemeningeal artery•Blood pools within the epiduralspace (i.e., between dura andcalvaria) causing a dangerousincrease in intra-cranial pressure
Fetal and infant skull•Some fibrous membranesbetween skull bones do not ossifyuntilafter birth creating distinctfontanelles (anterior andposterior).•The delayed ossification permitssome skull deformation at birthand accommodates the rapidgrowth of the brain
Anterior and Posterior Fontanelles
Clinical Note – Palpation of fontanelles•Palpation of the fontanelles is usefulfor monitoring the growth of thefrontal and parietal bones.•Dehydrated infants will havedepressed fontanelles•Bulging fontanelles indicatesincreased intra-cranial pressure
Clinical Note – Premature closure of the sutures(craniosynostosis)Absent or narrow anteriorfontanellePremature closure of thecoronal or lambdoid sutureunilaterallyPremature closure ofcoronal suture bilaterally
Neurocranium vs Viscerocranium
Neurocranium vs Viscerocranium•The viscerocranium provides theskeleton of the face•Bones – 2 lacrimal, 2 nasal, 2maxillae, 2 zygomatic, 2 palatine,2 inferior nasal conchae, a singlemandible and a single vomer•Contains the orbits, nasalcavities, upper and lower jaws
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Term
Fall
Professor
N/A
Tags
Facial nerve, trigeminal nerve