Anatomy: The Skull and Trauma
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Neonatal Skull:
o Frontal Suture (absent in adult)
o Nascent Sagittal Suture (between parietal bones)
o Nascent Coronal Suture (between frontal bone and parietal bones)
o Three Fontanelles:
 Posterior Fontanelle
 Mastoid Fontanelle
 Anterior Fontanelle
o Bones overlap because of these openings when coming out of the
birth canal.
o Skull grows in respect to brain growth, but neural skull has no room
to expand and no room if it gets compressed.
Neurocranium Bones: 8
o 2 Parietal Bones
o 2 Temporal Bones
o 1 Frontal Bone
o 1 Occipital Bone
o 1 Sphenoid Bone
o 1 Ethmoid Bone
Facial Bones: 14
o 2 Maxillae
o 2 Palatine Bones
o 2 Nasal Bones
o 2 Inferior Conchae
o 2 Zygomatic Bones
o 2 Lacrimal Bones
o 1 Vomer
o 1 Mandible
The Skull: Frontal View:
o Bones
 Frontal Bone
 Ethmoid Bone
 Zygomatic Bone
 2 Maxilla
 Mandible
 2 Nasal Bones
 Sphenoid Bone
o Foramina:
 Superior Orbital Foramen: Superior border of the eye
 Inferior Orbital Foramen: Inferior border of the eye
 Mental Foramen: On the mandible
Sutures of the Skull
o Coronal Suture: Separates Frontal Bone from Parietal Bones
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o Sagittal Suture: Separates two Parietal Bones
o Lambdoid Suture: Sagittal Suture divides, which separates the
Parietal, Occipital and the Temporal bones.
o ** Wormian Bone: Look like fractures of the skull in X-Rays, but they
are actually normal bones that are seen in certain populations like
Down’s syndrome and Brittle Bone Disease.
Cranial Fossae:
o Cribiform Plate – holds the Olfactory nerve.
o Crista Galli – Ridge in the Cribiform Plate, projection of the Ethmoid
Bone
o Clinoid Processes – Spikes on the Sphenoid Bone
o Sella Turcica – saddle-looking structure in the Sphenoid Bone that
contains the pituitary gland
o Petrous Ridge – On Temporal Bond
o Internal Occipital Ridge
Base of the Skull
o Carotid Canal – Internal Carotid Artery
o Jugular Foramen – For the Jugular Vein
Right Lateral View
o Zygomatic Bone:
 Squamous Portion: Thin, superior/middle portion of the bone
 Hard Portion is the bottom, where the zygomatic process is
 Squamous Suture: Separates the Temporal Bone from the
Occipital, Parietal, and Ethmoid Bones
 Pterion: Junction of the Sphenoid, Frontal, Parietal, and
Temporal bones that is the weakest part of the skull
Brain is Floating:
o Develops Dural Folds
 2 Layers of Dura:
 Periosteal Layer
 Dural Proper
 Falx Cerebri: The dural fold in between the two hemispheres
to prevent sideward motions of the brain
 Superior Sagittal Sinus – venous blood, in the apex of
the Falx Cerebri. Goes from the Crista Galli to the
Internal Occipital Ridge
o Tentorium:
 From the Clinoid Process to the Petrous Ridge so the brain
can’t move up and down.
o *** Nothing have evolved to help with compression.
Areas of Vunerability for Compression:
o Epidural Space: Potential Space between skull and periosteal layer of
dura
 Epidural Hematoma:
 If there is a blow to the Pterion:
Rips open the Middle Meningeal Artery and blood pours out
between the skull and the periosteal layer of the dura.
 Meningeal Artery and Vein:
o Nurture the Dura
o The Middle Meningeal Artery comes through the
Foramen Spinosum inside of the skull.
o These arteries developed before the skull, so
there are impressions on the skull from them.
(makes the skull thinner)
 Because it is arterial blood, it is under pressure, the
blood builds up and presses on the brain until it is
compressed.
 Compression is on the Temporal Lobe, which
compresses the Oculomotor nerve. Leads to Pupil
Dilation, Ptosis
 Rapidly Fatal: Patient has stupor, dizziness, then they
have a lucid period (were suddenly they are fine) and
then deteriorate very rapidly.
 USE CT SCAN, NOT MRI
o Subdural Space: Between Dura and Arachnoid.
 Veins drain into the Superior Sagittal Sinus (but they must go
through Arachnoid and Dura) which is why they drain through
the Subdural Space
 Sub-Dural Hematoma
 Venous blood between the Dura and the Arachnoid.
 Occurs where veins pierce the Sub-Arachnoid Space to
go into the Superior Sagittal Sinus
 Venous blood is under lower pressure.
 Because it is Subdural Space, the blood can travel larger
distances.
 Symptoms can come and go as venous pressure goes up
and down.
 Shaken Baby Syndrome: Child is lethargic, don’t focus.
 Roller Coaster Syndrome: Mainly affects older people.
o Arachnoid Granulations: Extensions of the Sub-Arachnoid Space into
the Superior Sagittal Sinus
Contusions:
o Gradual accumulation of damage
o Small localized lesions
o Can cause Parkinson’s Disease from being punched
Concussions: Chronic Traumatic Encelphalopathy
o Neurofibrillary Tangles accumulate until severe symptoms develop
 Stage 1: Depression, Headaches
 Stage 2: Depression, Mood Swings, Explosive Tendencies
 Stage 3: Problems in Judgment and Planning
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Stage 4: End stage with paranoia, dementia, aggressive
tendencies
The Ventricular System:
o Pneumocephalus:
 When you have a frontal sinus fracture and CSF pours out of
nose
The Venous System:
o Superficial Veins (scalp)
o Diploic Veins
o Super-Sagittal Sinus
o Superficial Temporal
 Route of Infection:
 Facial Vein  Angular Vein  Opthalamic Sinus 
Cavernous Sinus
o Pulsating Exophthalamos: where there is a
carotid aneurism in the Cavernous Sinus.
 Black eye. Exopthalmos (eye pulses in
and out)
 Superior Cerebral Veins  Superior Sagittal Sinus  Confluens
of the Sinus  Internal Jugular Vein
Stroke:
o Internal Carotid Artery  Middle Cerebral Artery  Striate Arteries
 Produce Ischemia in the Internal Capsul  Disrupts Corticospinal
Tract  Produce Paralysis on the Opposite Side
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