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Skull Osteology
LECOM Yr 1
86
Anatomy
Graduate
09/20/2011

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Term
where is the pterion located? describe its structure and what is located directly beneath it
Definition
runs right by sphenoparietal suture,

region is unique because several bones come together, temporal, parietal, sphenoid

bone is rather thin relative to other areas, middle meningeal branch that supplies specific areas of brain runs right beneath this area
Term
what is the cranium?
Definition
the skeleton of the head
Term
what joins the bones of the cranium?
Definition
The bones are joined by interlocking fibrous suture joints except for the mandible which articulates at the synovial temporomandibular joint

Sphenoid and occipital bone are united by hyaline cartilage (synchondrosis) during childhood
Term
the cranium can be divided into what 2 parts?
Definition
neurocranium and viscerocranium
Term
the only real moveable joint in the cranium is the?
Definition
temporomandibular joint
Term
what composes the neurocranium and what does it contain?
Definition
Bony covering of the brain and its meninges

Contains the proximal parts of the cranial nerves and the vasculature of the brain

Comprised of 8 bones: frontal, 2 parietal, 2 temporal, occipital, sphenoid, and ethmoid

Has a calvaria (skull cap) and a cranial base or floor
Term
describe the bones of the calvaria in the neurocranium
Definition
skull cap

Bones of the calvaria are flat bones derived from neural crest tissue that becomes head mesenchyme

Flat bones of the calvaria are formed by intramembranous ossification
Term
flat bones of the calvaria are derived from?
Definition
neural crest tissue
Term
flat bones of the calvaria are formed by _______ ossification.
Definition
intramembranous
Term
bones of the cranial base are formed by __________ ossification.
Definition
endochondral or both methods
Term
what are the bones of the viscerocranium?
Definition
Viscerocranium has 14 bones

2 lacrimal, 2 nasal, 2 maxillae, 2 zygomatic, 2 palatine, 2 inferior nasal conchae, mandible, and vomer

Contains the orbits (eye sockets) and nasal cavities, upper and lower jaws
Term
the calvaria have 2 layers of compact bone with a spongy bone layer in between termed?
Definition
diploe
Term
arachnoid granulations leave impressions on what part of the calvaria?
Definition
protrude cranially and leave impressions on the interior superior aspect of the calvaria
Term
what is the pericranium?
Definition
the periosteum of the cranium
Term
the compact bone layers of the calvaria are frequently termed?
Definition
inner and outer tables
Term
what does the diploe of the calvaria transmit?
Definition
transmits the diploic veins that communicate with the cranial dural sinuses via emissary veins

contains red marrow early in life
Term
which bone is the cheek bone?
Definition
zygomatic bone
Term
what does the frontal bone form?
Definition
the skeleton of the forehead
Term
what makes up the nasal septum?
Definition
Nasal septum divides nasal cavity in two halves and is predominantly made up of the perpendicular plate of the ethmoid bone and the vomer, but also includes the palatine bone
Term
where are nasal conchae located?
Definition
Nasal conchae (curved bony plates) occupy lateral wall of nasal cavity

Superior and middle conchae are part of the ethmoid bone. The inferior nasal conchae are individual bones.
Term
what does the maxillae bone form?
Definition
Maxillae form the upper jaw and contain the alveolar process which include the tooth sockets (alveoli).

Paired maxillae unite at the intermaxillary suture
Term
what does the mandible hold?
Definition
mandibular teeth
Term
describe what injury of the ethmoid bone may cause
Definition
The ethmoid bone is easily injured by a sharp upward blow to the nose, such as a person might suffer by striking an automobile dashboard in a collision

Force of the blow can drive bone fragments through the cribriform plate into the meninges or brain tissue

This can cause leakage of cerebrospinal fluid into the nasal cavity and maybe followed by the spread of infection from the nasal cavity to the brain

CSF may leak out of nasal cavity
Term
the piriform aperture is an opening in the skull for which cavity?
Definition
the nasal cavity
Term
the foramina of the anterior skull allow for passage of sensory branches from which nerve?
Definition
the trigeminal nerve
Term
the supraorbital notch transmits what vessels?
Definition
the supraorbital nerve and vessels
Term
the zygomaticofacial foramen transmits which nerve?
Definition
the zygomaticofacial nerve
Term
the infraorbital foramen transmits which vessels?
Definition
the infraorbital nerve and vessels
Term
the mental foramen transmits which vessels?
Definition
the mental nerve and vessels
Term
the optic canal goes through which bone?
Definition
the sphenoid bone
Term
what is the glabella?
Definition
a reference point on the anterior skull

Glabella is the prominence of frontal bone above root of nose (depression between the supercilliary arches)
Term
what are superciliary arches and what are their clinical importance?
Definition
Superciliary arches are relatively sharp ridges and a blow here, such as during a boxing match or fist fight, may lacerate the skin and cause bleeding. Tissue fluid and blood can accumulate around the orbit and into the thin skin of the eyelids leaving a “black eye” (echymosis).
Term
where do tears drain?
Definition
in the lacrimal sac/depression
Term
what are sutures?
Definition
Sutures are fibrous joints between the bones of the skull

At ages 30-40 the sutures of the calvaria begin obliteration on the internal surface and about 10 years later on the external surface

if you see the skull of an elderly individual you may not even see sutures; bone is completely remodeled so there's almost no trace of sutures and no mobility at this point
Term
what is craniosynostosis?
Definition
the premature closure of the cranial sutures

it results in cranial malformations

1 in 2000 births
Term
the coronal suture lies between which bones?
Definition
the frontal bone and the 2 parietal bones
Term
the sagittal suture lies between which bones?
Definition
the 2 parietal bones
Term
the squamous suture lies between which bones?
Definition
the parietal bone and the squamous part of the temporal bone
Term
the lambdoid suture lies between which bones?
Definition
(resembles Greek letter λ) lies between the two parietal bones and the occipital bone
Term
where can sutural (wormian) bones be found?
Definition
occur along the lambdoid suture
Term
if an infant has hydrocephalous, you will see more of which bones?
Definition
wormian bones
Term
what are found on the parietal bone?
Definition
superior and inferior temporal lines
Term
what can be found on the temporal bone?
Definition
has mastoid and styloid processes, zygomatic arch, external acoustic meatus, and a squamous part
Term
where is the lacrimal bone located?
Definition
in the medial wall of the orbit
Term
what can be found on the occipital bone?
Definition
Occipital bone has external occipital protuberance (inion) and superior & inferior nuchal lines
Term
where is the lambda landmark located?
Definition
junction of the lambdoid and sagittal sutures
Term
where is the bregma landmark located?
Definition
junction of the sagittal and coronal sutures
Term
where is the pterion landmark located?
Definition
junction of frontal, parietal, temporal bones, and greater wing of the sphenoid on the lateral aspect of the skull

Clinical significance: It is a thin part of the calvaria overlying anterior branch of the middle meningeal artery
Term
where is the nasion landmark located?
Definition
intersection of the frontal and 2 nasal bones
Term
what is the vertex?
Definition
the highest point of the superior aspect of the skull
Term
what is the glabella?
Definition
Glabella is the prominence of frontal bone above root of nose (depression between the supercilliary arches)

is a reference point
Term
fracture of the pterion can result in what?
Definition
Fracture of the pterion can result in rupture of the anterior branch of the middle meningeal artery causing an extradural “epidural” hematoma

extremely dangerous

bleeding under high pressure outside of the dura
Term
describe some signs of an epidural hematoma
Definition
A fracture at the pterion, the thinnest part of the calvaria may lacerate the anterior branch of the middle meningeal artery causing a epidural hematoma.

The hematoma may compress the lateral part of the cerebral hemisphere and result in herniation of the medial part of the temporal lobe through the tentorial notch of dura. This in turn compresses the brainstem causing all or some of these signs: limb weakness, dilated pupil from compression of the oculomotor nerve, and deterioration of cardiovascular and respiratory function.

These neurological signs may occur several hours after the initial injury, as blood accumulates to the point at which pressure on the brain reaches a critical value.

patient may experience a lot of pain, may cause momentary loss of consciousness

eventually will compress brain after a few hours, occulomotor nerve, dilated pupil, limb weakness, can herniate brain or put pressure on brain stem (vegetative state)
Term
on the internal surface of the cranial base, which is the shallowest of the cranial fossae?
Definition
the anterior cranial fossa
Term
which bones make up the anterior cranial fossa?
Definition
frontal bone, ethmoid, body and lesser wings of the sphenoid
Term
what does the middle cranial fossa contain?
Definition
the sella turcica
Term
which is the largest of the 3 cranial fossa in the cranial base?
Definition
posterior cranial fossa

comprised mostly of occipital bone

holds cerebellum, pons and medulla
Term
which foramen and features can be found in the anterior cranial fossa?
Definition
Foramen cecum
Olfactory foramina of cribriform plate
Anterior and posterior ethmoidal foramina
Term
which foramen and features can be found in the middle cranial fossa?
Definition
Optic canal
Superior orbital fissure
Foramen rotundum
Foramen ovale
Foramen spinosum
Carotid canal
Hiatuses and canals for the greater and lesser petrosal nerves
Foramen lacerum (only a foramen in a preserved skull, in life it is filled with cartilage)
Term
which foramen and features can be found in the posterior cranial fossa?
Definition
Internal acoustic meatus
Jugular foramen
Hypoglossal canal
Foramen magnum
Condylar canal
Term
what runs through the optic canal?
Definition
Optic nerve (CN II)
Ophthalmic artery
Term
what is found in the superior orbital fissure?
Definition
Oculomotor nerve (CN III)
Trochlear nerve (CN IV)
Lacrimal, frontal and nasociliary branches of ophthalmic nerve (CN V1)
Abducent nerve (CN VI)
Superior ophthalmic vein
Term
what runs through the foramen rotundum?
Definition
Maxillary nerve (CN V2)
Term
what runs through the foramen ovale?
Definition
Mandibular nerve (CN V3)
Accessory meningeal artery
Lesser petrosal nerve
Term
what runs through the foramen spinosum?
Definition
Middle meningeal artery and vein
Meningeal branch of mandibular nerve
Term
what runs through the carotid canal?
Definition
Internal carotid artery with internal carotid nerve plexus
Term
what can be found in the foramen lacerum?
Definition
It is filled with cartilage. The greater petrosal nerve passes horizontally across foramen lacerum and traverses the cartilage.
Term
what can be found in the internal acoustic meatus?
Definition
Facial nerve (CN VII)
Vestibulocochlear nerve (CN VIII)
Labyrinthine artery
Term
what can be found in the jugular foramen?
Definition
Inferior petrosal sinus
Glossopharyngeal nerve (CN IX)
Vagus nerve (CN X)
Accessory nerve (CN XI)
Sigmoid sinus
Posterior meningeal artery
Term
the carotid canal and foramen lacerum are located in which cranial fossa?
Definition
the middle cranial fossa
Term
the internal acoustic meatus and jugular foramen are located in which cranial fossa?
Definition
posterior cranial fossa
Term
what can be found in the hypoglossal canal?
Definition
the hypoglossal nerve (XII)
Term
what can be found in the foramen magnum?
Definition
Medulla oblongata
Meninges
Vertebral arteries
Meningeal branches of vertebral arteries
Spinal roots of accessory nerves
Term
the hypoglossal canal and foramen magnum are located in which cranial fossa?
Definition
the posterior cranial fossa
Term
the hard palate of the external cranial base is formed by which bones?
Definition
The hard palate is formed by the palatine process of the maxillae anteriorly and the horizontal plates of the palatine bone posteriorly
Term
what can be found superior to the posterior edge of the hard palate (of the external cranial base)?
Definition
Superior to the posterior edge of the palate are 2 large openings, the choanae (posterior nasal apertures)
Term
what can be found in the incisive foramen?
Definition
the nasopalantine nerve (it is posterior to the central incisor teeth)
Term
the greater and lesser palantine foramina transmit what vessels?
Definition
Greater & lesser palatine foramina transmit the greater & lesser palatine nerves and vessels
Term
the stylomastoid foramen transmits which nerve?
Definition
the facial nerve
Term
what can be found in the carotid canal?
Definition
Carotid canal transmits the internal carotid artery and sympathetic plexus
Term
what are sinuses?
Definition
air filled spaces lined with mucosa
Term
where is the frontal sinus located?
Definition
right in the middle of the frontal bone
Term
what are fontanelles?
Definition
soft spots

Regions of membrane between skull bones that are not yet ossified. The membrane is blended with the pericranium externally, and the dura matter internally. They allow skull deformation during birth and allow for rapid brain growth of the brain during the 1st two years.
The fontanelles are usually closed by the 2nd year.

flat bones develop through intramembranous ossification, stay membranous for first two years of life, then they ossify
Term
palpation of the fontanelles during infancy allows the physician to determine what?
Definition
Progress of growth of frontal and parietal bones

Degree of hydration
a depressed fontanelle indicates dehydration and can occur after a bought of severe fever or diarrhea

Level of intracranial pressure
bulging fontanelle indicates increased pressure on the brain
Term
where is the metopic suture found in the infant skull?
Definition
Metopic suture lies between 2 developing frontal bones

Allows skull deformation during the birthing process

Closes during the 6th year leaving 1 frontal bone in the adult skull (there is short remnant of the metopic suture superior to the nasion)
Term
deformation of the calvaria (cone head) during the birth process is allowed by what structures?
Definition
fibrous sutures and fontanelles
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