skull complete slides 2013
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The Skull (I):jjjj
Cranial Vault & Base
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Skull
The sup. part of axial sk., that:
1. Covers & protect the brain
2. Provides facial sk. (shape of face)
Skull = 22 bones:
1. Bones of braincase
2. Facial bones
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Bones of Braincase (8 bones)
Frontal
(1)
Parietal
(2)
Occipital
(1)
Temporal
(2)
Sphenoid
(1)
Ethmoid
(1)
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Facial Bones (14 bones)
Zygomatic (2)
Maxilla (2)
Nasal (2)
Lacrimal (2) Vomer (1)
Palatine (2)
Inferior Conchae (2)
Mandible (1)
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The Cranium
Cranium = Skull – Mandible
Divided into:
Braincase (neurocranium)
Upper facial sk. ( face bones,
viscerocranium)
* Usually most physicians refer to the
whole skull as cranium
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Bones of braincase
1. Cranial Vault:
- forms the roof & sides of brain box
- (Frontal, Parietal, Squamous of occipital, squamous of
temporal & greater wing of sphenoid)
- fibrous joints (sutures)
2. Cranial Base:
- forms the floor of brain box
- (orbital frontal, ethmoid, sphenoid, petrous temporal & basilar
occipit)
- cartilaginous joints centrally (why?)
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Cranial Vault (Calvaria)
Oval in shape & broadens post.
Made up of:
which bones?
Cran. Vault bones are:
Diploic Bones
Extensions:
Supraorbital margins (ant.)
Sup. Nuchal line & EOP (post.)
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Cranial Vault
3 sutures:
1. Coronal suture
which bones?
2. Sagittal suture
which bones?
3. Lambdoid suturewhich bones?
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4 points
1. Bregma:
intersection of sagittal & coronalsutures
2. Vertex:
sup. topmost point of the cranium
3. Lambda:
intersection of sagittal & lambdoid
sutures
4. Pterion: (G, pteron: wing)
-sup. to midpoint of zyg. arch
-indicated by H-shaped sutures
-very dangerous area ( why? )
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Cranial Base (Base of The Skull)
The floor of brain box
2 surfaces
I. Internal surface (endocranial):
3 fossae (depressions)
Ant., Middle, & Post.
II. External surface:
inf. aspect of the skull
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Anterior Cranial Fossa
Made of:
1.Orbital plates of frontal bone:
anterolateral
frontal crest & foramen cecum
2.Lesser wing of sphenoidposteriorly, sharp boundary
3.Cribriform plate of ethmoid
central, roof of nasal cavity
perforated for transmission of olf. Ns.
*crista galli: (L, cock’s comb)
median projection from crib. Ethmoid that
provides attachment site for meninges
Ant. Fossa = 2 foramina ?
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Middle Cranial Fossa
Butterfly-shaped:
Centrally:
sella turcica (sphenoid body)
Laterally:
2 depressed parts
Extensions:
Post. wing of sphenoid
Sup. Border of petrous temporal
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Sella Turcica
Composed of 1. Tuberculum sellae:
Ant. elevation
horn of the saddle
2. Hypophysial fossa:pituitary fossa
3. Dorsum sellae:
post. bony elevation
back of the saddle
Surrounded by:
clinoid processes (bed post)
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Sphenoid Bone
Middle of skull base (keystone)
Consist of:
Body:
sphenoid air sinuses
Greater Wing
floor of ??
Lesser Wing
post. part of ??Pterygoid processes:
(legs)
pterygoid plates
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Foramina in Middle Cranial Fossa
1. Optic canal:lesser wing
optic n.
2. Sup. Orbital fissure:
between lesser & greater
wings
communicates?
3. Foramen Rotundum: (round)greater wing
post. to medial end of
sup. Orbital fissure
V2
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4. Foramen ovale: (oval)
greater wing,
posterolat. to rotundum
V3
5. Foramen Spinosum:
greater wingposterolat. To ovale
middle meningeal a.
6. Foramen Lacerum:
between sphenoid & temporal
coverd by cartilage in life
artificate foramen after death
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Posterior Cranial Fossa
The largest & deepest fossa
Made of:
post. surface of petrous temporal
occipital bone
(basilar & condylar)
very small portion of
sphenoid body
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Centrally:
Clivus
F. Magnum
Int. Occipital Crest
IOP
2 broad grooves
(linear depressions)
Transverse V. Sinuses
Sigmoid V. Sinuses
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Foramina in Post. Fossa
1. Foramen Magnum
occipital bone (basilar)
M. oblongata & meninges,
V.a., spinal XI
2. Jugular Foramen:
between temporal & occipital
Int. Jugular V. & ???
3. Hypoglossal Canal:
anterolat. Wall of F. magnumXII
4. Int. Acoustic Meatus:
ant. to jugular, VII & VIII
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External Surface of Cranial Base
(Inf. Aspect of Skull)
Facial Sk. (viscerocranial) Part:
Alveolar Processes of Maxillae
Palatine Processes of Maxillae*
Horizontal Plates of Palatine Bone*
Vomer
*Hard Palate*
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Braincase (neurocranial) Bones:
Sphenoid
pterygoid plates & greater wing
Temporal Bone:
mandibular fossa
styloid & mastoid processes
S-M foramen & carotid canal
Occipital Bone:which parts?
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Skull (II):
Facial Skeleton
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Facial Bones (14 bones)
Zygomatic (2)
Maxilla (2)
Nasal (2)
Lacrimal (2) Vomer (1)
Palatine (2)
Inferior Conchae (2)
Mandible (1)
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Divided into
Forehead
frontal
Orbital cavities:
pyramidal, 4 walls
Nasal cavity
Jaws:
maxillae & mandible
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Forehead
Made by: forntal bone
*Nasion:
intersection of frontal & nasal
bones
*Metopic suture (frontal):
in immature skulls
in median plane
usually fuses in early childhood
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Orbital Cavity
Pyramidal in shape, 4 walls?
Contains:
eyeball & lacrimal apparatus
2 fissures (inside):
Sup. Orbital fissure
between?, communicates?
Inf. orbital fissure
between?, communicates?
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Nasal Cavity
Located between:
Ant. Cranial Fossa
&
Oral Cavity
Nasal Septum:
Rt. & Lf.
1. perp. Plate of ethmoid
2. vomer
Nasal Conchae:
lateral wall
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Maxilla
Body & 4 Processes
Body:
pyramidal
hollow inside (max. sinus)
2 foramina:
Infraorbital F.
ant. wall, infraorbital n.
Incisive Foramen:
between palatine processes
post. to central incisors
incisive n. (nasopalatine n.)
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Maxillary Processes
Zygomatic:
projects lat.,ant. zyg. Arch
Frontal:
sup.,
lat. to nasal bones
Alveolar:
inf.,
contains upper teeth
Palatine:
post.,
ant. 2/3 of hard palate
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Largest & strongest facial bone
Only movable skull bone
Horizontal part:
Body
Vertical Parts:
Rami (ramus)
Jxn.:
Angle
Mandible
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Body:
mental foramen
alveolar process
Ramus:
mandibular notchcoronoid process
condylar process:
head & neck
lingula & mand. foramen
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Paranasal Sinuses
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Paranasal Sinuses
Air-containing spaces within cranial bones
Lined with respiratory epithelium in life (which type?)
Suggested Fxn.’s:
1. reduce skull weight
2. voice modification (sinusitis?)
3. insulation effect:prevent heat loss from nasal cavity
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1. Maxillary Sinuses
maxillary bones, pyramidal
middle meatus
2. Frontal Sinuses
frontal bone, above the orbit
middle meatus
3. Sphenoid sinuses
sphenoid body
both sinuses separated by
septum
sphenoethmoidal recess
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4. Ethomidal air cells:
ant. & middle:
middle meatus
Post.:
sup. Meatus
5. Mastoid air cells:temporal
middle ear
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Skull (III):
Skull Fractures
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Fractures of Calvaria
• Fracture Resistance:
- Convexity of the skull
- Diploid bone
•
Fracture Types:1. Linear fractures (most frequent )
2. Depressed fractures (thin areas)
3. Comminuted fractures (strong blow, several pieces)
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Pterion Fractures
Pterion is a dangerous region of the skull:
1. Point of weakness
H-shape suture
2. Ant. branch of middle meningeal artery
(Epidural hemorrhage)
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Cranial Base Fractures
Anterior Cranial Fossa Fractures:
damage to crib. Plate of ethmoid
Nasal bleeding “epistaxis”
Tearing of meninges
CSF leakage into nose
“cerebrospinal rhinorrhea”
Fract. Of orbital plate of frontal bone
Bleeding into orbital cavity
“exophthalmos”
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Middle Cranial Fossa Fractures:
Common fractures Because it is the ?? part of the base of skull due to ???
CSF leakeage through EAM
inj. To 3rd – 6th cranial nerves
Posterior Cranial Fossa Fractures:
Bleeding into post. Vertb. Muscles
Inj. To 9th – 11th cranial nerves
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Facial Fractures
3 Types (planes of weakness)
Le Fort I
transmaxillary
Le Fort IIpyramidal, subzygomatic
(max., lacrimal, nasal)
Le Fort III
suprazygomatic, craniofacial
whole upper facial sk. detached
Usually complicated e soft tissue damage (hemorrhage, edema, pain)
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Nasal Bone Fracture
Most frequent facial fracture
Most commonly in Boxer’s
Complications:
fracture of orbital margin
injury to frontal or ethmoidal
sinuses
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Mandibular Fractures
1. Condylar Fractures:
most common + body
blow to chin when mouth is open
2. Body Fractures:
most common + condylar
usually near canine region:
-root length
-max. covexity
blow to the side of the jaw
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3. Fractures of the Angle:
2nd most common
2directions:
downwards backwards
dislocation
downwards forwards
4. Coronoid Process Fracture:
least common (1-2%)
temporalis attachment
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Mandibular Fractures 2nd most frequent after Nasal fractures
Notes:
1. If you see a fracture or dislocation in the mandible, look for another
fracture or dislocation
2. Panoramic x-ray is the best to diagnose mandibular fractures
3. Look for cortical margin & mandibular canal discontinuity
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Panoramic X-ray