skull complete slides 2013

7/29/2019 Skull Complete Slides 2013

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The Skull (I):jjjj

Cranial Vault & Base



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



Bones of Braincase (8 bones)

Frontal

(1)

Parietal

(2)

Occipital

(1)

Temporal

(2)

Sphenoid

(1)

Ethmoid

(1)



Facial Bones (14 bones)

Zygomatic (2)

Maxilla (2)

Nasal (2)

Lacrimal (2) Vomer (1)

Palatine (2)

Inferior Conchae (2)

Mandible (1)



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



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?)



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.)



Cranial Vault

3 sutures:

1. Coronal suture

which bones?

2. Sagittal suture

which bones?

3. Lambdoid suturewhich bones?



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? )



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



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 ?



Middle Cranial Fossa

Butterfly-shaped:

Centrally:

sella turcica (sphenoid body)

Laterally:

2 depressed parts

Extensions:

Post. wing of sphenoid

Sup. Border of petrous temporal



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)



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



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



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



Posterior Cranial Fossa

The largest & deepest fossa

Made of:

post. surface of petrous temporal

occipital bone

(basilar & condylar)

very small portion of

sphenoid body



Centrally:

Clivus

F. Magnum

Int. Occipital Crest

IOP

2 broad grooves

(linear depressions)

Transverse V. Sinuses

Sigmoid V. Sinuses



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



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*



Braincase (neurocranial) Bones:

Sphenoid

pterygoid plates & greater wing

Temporal Bone:

mandibular fossa

styloid & mastoid processes

S-M foramen & carotid canal

Occipital Bone:which parts?



Skull (II):

Facial Skeleton



Facial Bones (14 bones)

Zygomatic (2)

Maxilla (2)

Nasal (2)

Lacrimal (2) Vomer (1)

Palatine (2)

Inferior Conchae (2)

Mandible (1)



Divided into

Forehead

frontal

Orbital cavities:

pyramidal, 4 walls

Nasal cavity

Jaws:

maxillae & mandible



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



Orbital Cavity

Pyramidal in shape, 4 walls?

Contains:

eyeball & lacrimal apparatus

2 fissures (inside):

Sup. Orbital fissure

between?, communicates?

Inf. orbital fissure

between?, communicates?



Nasal Cavity

Located between:

Ant. Cranial Fossa

&

Oral Cavity

Nasal Septum:

Rt. & Lf.

1. perp. Plate of ethmoid

2. vomer

Nasal Conchae:

lateral wall



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.)



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



Largest & strongest facial bone

Only movable skull bone

Horizontal part:

Body

Vertical Parts:

Rami (ramus)

Jxn.:

Angle

Mandible



Body:

mental foramen

alveolar process

Ramus:

mandibular notchcoronoid process

condylar process:

head & neck

lingula & mand. foramen



Paranasal Sinuses



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



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



4. Ethomidal air cells:

ant. & middle:

middle meatus

Post.:

sup. Meatus

5. Mastoid air cells:temporal

middle ear



Skull (III):

Skull Fractures



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)



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)



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”



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



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)



Nasal Bone Fracture

Most frequent facial fracture

Most commonly in Boxer’s

Complications:

fracture of orbital margin

injury to frontal or ethmoidal

sinuses



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



3. Fractures of the Angle:

2nd most common

2directions:

downwards backwards

dislocation

downwards forwards

4. Coronoid Process Fracture:

least common (1-2%)

temporalis attachment



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



Panoramic X-ray

skull complete slides 2013

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