Download Anterior cranial fossa

DEPARTMENT OF ANATOMY
Head and Neck
Dr. SREEKANTH THOTA
Bones of the Skull
• The skull bones are made up of external
and internal tables of compact bone
separated by a layer of spongy bone
called the diploe.
COMPONENT PARTS
• The skull has 22 bones,
excluding the ossicles of the
ear.
• Except for the mandible,
which forms the lower jaw, the
bones of the skull are
attached to each other by
sutures, are immobile, and
form the cranium.
Subdivisons
• 1.The cranium can be
subdivided into: an upper part
the calvaria, which surrounds
the cranial cavity containing
the brain(Neurocranium).
2.Lower anterior part-the
facial skeleton
(viscerocranium).
The cranium consists of the following bones,
two of which are paired
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Frontal bone: 1
Parietal bones: 2
Occipital bone: 1
Temporal bones: 2
Sphenoid bone: 1
Ethmoid bone: 1
• The facial bones consist of the following, two of which
are single:
• Zygomatic bones: 2
• Maxillae: 2
• Nasal bones: 2
• Lacrimal bones: 2
• Vomer: 1
• Palatine bones: 2
• Inferior conchae: 2
• Mandible: 1
Frankfort horizontal line(anatomical position of
Cranium)
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Horizontal plane represented by a line between Upper rim of
the external auditory canal( auricular point), to the lower rim of
the orbit( infraorbital point).
• FHL divides the head into upper and lower halves.
External Views of the Skull
• Anterior View of the Skull(Norma frontalis)
The anterior view of the skull includes the
forehead superiorly, and, inferiorly, the
orbits, the nasal region, the part of the
face between the orbit and the lower jaw
Foramen of Anterior view
• 1. Supra-orbital foramen: Supra-orbital
nerve and vessels.
• 2. Infra-orbital foramen: Infra-orbital nerve
and vessels.
• 3. Mental foramen: Mental nerve and
vessels
Superior view of the skull(Norma verticalis)
• Parietal foramen: Emissary veins
Bregma and Lambda
Posterior view of the skull(Norma occipitalis)
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Lateral view of skull(norma lateralis)
• Zygomaticofacial foramen: Zygomaticofacial nerve
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© 2005 Elsevier
Temporal bone
Petrous portion of Temporal bone
Fracture of the Pterion
A hard blow to the
side of the head may
fracture the thin
bones forming the
pterion, producing a
rupture of the anterior
branch of the middle
meningeal artery
crossing the pterion
Inferior view of the skull.
Foramen
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1. Incisive fossa
2. Greater and lesser palatine foramina
3.Jugular foramen
4.Carotid canal
5.Stylomastoid foramen
6.Foramen magnum
Skull
Cranial fossa
Internal Surface of the Cranial Base
• The internal surface of the cranial base
has three large depressions that lie at
different levels: the anterior, middle, and
posterior cranial fossae .
Anterior cranial fossa
Foramen of Anterior cranial
fossa
• 1. Cribriform plate:olfactory nerves (CN-I)
• 2. Foramen cecum: occasional small emissary vein from nasal
mucosa to superior sagittal sinus.
• 3. Anterior and posterior ethmoidal foramina: anterior and
posterior ethmoidal nerves, arteries, and veins.
Middle cranial fossa-
Foramen of Middle cranial fossa
1. Optic canal: optic nerve (CN II), ophthalmic artery.
2.Superior orbital fissure: oculomotor (CN III),
trochlear (CN IV), and abducens (CN VI) nerves; ophthalmic
division of trigeminal nerve (CN V1) and ophthalmic veins.
3. Foramen rotundum: Maxillary nerve
• 4. Foramen ovale: Mandibular nerve, the accessory
meningeal artery, and the lesser petrosal nerve.
• 5. Foramen spinosum: middle meningeal artery.
Posterior cranial fossa
Foramen of posterior cranial
fossa
• Foramen magnum: medulla, the ascending portions of
the spinal accessory nerve (XI), and the vertebral arteries.
• Internal acoustic meatus:facial (VII)
and vestibulocochlear (VIII) cranial nerves
• Jugular foramen: internal jugular vein (actually begins
here), the glossopharyngeal (IX), the vagus (X) and the
accessory (XI) nerves.
• Anterior condylar (hypoglossal) canal:
hypoglossal (XII) nerve.
Fractures of the Calvaria
A depressed skull fracture is a break in a cranial bone (or "crushed" portion of skull) with
depression of the bone in toward the brain.
A compound fracture involves a break in, or loss of, skin and splintering of the bone.
Contrecoup (counterblow) fracture
• No fracture occurs at the point of impact, but one occurs on
the opposite side of the cranium.
When a moving object impacts the stationary head, coup injuries
are typical, while contrecoup injuries are produced when the
moving head strikes a stationary object
Fractures to the Maxilla and
associated bones
• Le Fort I Fracture = Horizontal Fracture
• Le Fort II Fracture = Pyramidal Fracture
• Le Fort III Fractures = Craniofacial
Separation