Download MBBS The Skull Lecture PPT

NORMA LATERALIS
? The skull is viewed from the sides.
? It is demarcated from other views by the temporal lines.
? Bones viewed in Norma lateralis:

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? Frontal bone
? Parietal bone
? Sphenoid: a) Greater wing b) Lateral pterygoid plate
? Temporal bone: a) Squamous part b) Styloid process c) Mastoid part
? Zygomatic bone

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? Maxilla
? Occipital bone
? Nasal bone

NORMA LATERALIS

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? Important structures to be identified are:
1. Temporal lines

11.Mastoid foramen

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2. Supra mastoid crest

12.Temporal fossa

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3. Zygomatic arch

13.Styloid process

4. External auditory meatus 14.Infra temporal fossa

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5. Squamo-tympanic suture 15.Pterygopalatine fossa

6. Supra meatal spine

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16.Sphenopalatine foramen

7. Supra meatal triangle

17.Greater palatine canal

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8. Parieto-mastoid suture

9. Occipito-mastoid suture

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10.Mastoid process

NORMA LATERALIS

TEMPORAL FOSSA:

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? Depressed area below the temporal lines.
? Boundaries:
?Anteriorly:

i. Temporal surface of zygomatic process of frontal.

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ii. Frontal process of zygomatic.

iii. Greater wing of sphenoid.
?Posteriorly:

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i. Posterior part of superior temporal line.

ii. Supra mastoid crest.
?Superiorly: superior temporal line.

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?Inferiorly:

i. Laterally: zygomatic arch.

ii. Medially: infratemporal crest.

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?Floor gives origin to temporalis muscle.

NORMA LATERALIS

TEMPORAL FOSSA

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? Contents:
1. Temporalis muscle

with its fascia.

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2. Two deep temporal

nerves.

3. Temporal branches

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of maxillary artery.

4. Zygomatico-

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temporal nerves.
NORMA LATERALIS
INFRA TEMPORAL FOSSA
? Irregular space situated behind the maxilla and below the zygomatic arch.
? Boundaries:

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?Medially:
i. Lateral pterygoid plate.
ii. Pyramidal process of palatine bone
?Anteriorly:
i. Posterior surface of maxilla.

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ii. Medial surface of zygomatic bone.
?Roof:
i. Infra temporal surface of greater wing to sphenoid.
ii. Squamous part of temporal bone.

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NORMA LATERALIS

INFRA TEMPORAL FOSSA:
?Above it communicates with temporal fossa.
?It is open on its posterior, lateral and inferior aspects.

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?Laterally ramus of mandible forms its boundary.
?Anterior and medial walls are separated in the upper

part by pterygomaxillary fissure, while they meet below.

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?Through pterygomaxillary fissure, this fossa

communicates with the pterygopalatine fossa.

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NORMA LATERALIS

INFRA TEMPORAL FOSSA:
? Contents:

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1. Muscles:

a) Lateral pterygoid

b) Medial pterygoid

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2. Nerves:

a) Mandibular and its branches

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b) Corda tympani

c) Maxillary

3. Vessels:

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a) Maxillary artery and its branches

b) Middle meningeal artery

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c) Maxillary vein.

d) Pterygoid plexus of veins.
NORMA LATERALIS

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PTERYGOPALATINE FOSSA:
? Small pyramidal space lying below the apex of the orbit.
? Boundaries:
?Anteriorly: supero-medial part of posterior surface of maxilla.
?Posteriorly: root of pterygoid process and adjoining part of greater wing of

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sphenoid.

?Medially: upper part of lateral surface of perpendicular plate of palatine bone

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with its orbital and sphenoidal process.

?Roof: formed by under surface of body of sphenoid.
?Floor: formed by meeting of anterior and posterior walls.
?Laterally: It communicates with the infra temporal fossa through

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pterygomaxillary fissure.

NORMA LATERALIS
PTERYGOPALATINE FOSSA:

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? Communications:
?5 Openings and 2 fissures in this fossa.
?3 openings in the posterior wall. They are:
1. Foramen rotendum
2. Pterygoid canal

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3. Palato-vaginal canal
?On the medial wall is the opening of spheno-platine foramen.
? Greater palatine foramen opens at the place where anterior and posterior walls

meet.

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?Fissures are: pterygomaxillary fissure and inferior orbital fissure.

NORMA LATERALIS
PTERYGOPALATINE FOSSA:

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? The fossa communicates with:
1. Infra temporal fossa through pterygomaxillary fissure.
2. Orbital cavity through inferior orbital fissure.
3. Middle cranial fossa through foramen rotendum.
4. Roof of nasal cavity and pharynx through palate-vaginal canal.

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5. Nasal cavity through sphenopalatine foramen.
6. Roof of oral cavity through greater palatine foramen.

NORMA LATERALIS

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PTERYGOPALATINE FOSSA:
?Contents:

1. Maxillary artery and its branches.

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2. Maxillary nerve in its course to the orbit. The

nerve enters the fossa through foramen rotendum.

3. Pterygopalatine/sphenopalatine ganglion with its

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branches ( orbital, palatine, nasal and pharyngeal)

4. Pterygoid nerve.

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NORMA OCCIPITALIS
NORMA OCCIPITALIS
?Norma occipitalis is convex upwards and on each

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side, and is flattened below.

?Bones seen are:
1. Posterior part of parietal bones, above.
2. Upper part of squamous par of the occipital bone

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below.

3. Mastoid part of the temporal bone, on each side.
NORMA OCCIPITALIS

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?Sutures seen are:
1. LAMBDOID SUTURE: between the occipital and two

parietal bones.

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2. OCCIPITO MASTOID SUTURE: between the occipital

and mastoid part of temporal bone.

3. PARIETOMASTOID SUTURE: between the parietal bone

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and mastoid part of temporal bone.

4. SAGITTAL SUTURE: the posterior part is also seen.

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NORMA OCCIPITALIS
EXTERNAL OCCIPITAL

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PROTUBERANCE:
? Is a median prominence

in the lower part of this

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norma.

? It marks the junction of

the head and the neck.

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? The most prominent

point on this

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protuberance is called

the inion.

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NORMA OCCIPITALIS
SUPERIOR NUCHAL

LINES:
? Are curved bony

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ridges passing

laterally from the

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protuberance.

?These also mark

the junction of the

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head and the neck.


NORMA OCCIPITALIS

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HIGHEST NUCHAL LINES:

? Are not always present.

? They are curved bony

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ridges situated 1 cm

above the superior

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nuchal lines.

? They begin from the

upper part of the

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external occipital

protuberance.

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? Are more arched than

the superior nuchal lines.
NORMA OCCIPITALIS
OCCIPITAL POINT:

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?It is a median

point a little

above the inion.

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?It is the point

farthest from the

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glabella.


NORMA OCCIPITALIS
THE MASTOID FORAMEN:

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? Located on the mastoid

part of temporal bone at

or near the

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occipitomastoid suture.

? Internally, it opens at the

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sigmoid sulcus.

? The mastoid foramen

transmits an emissary

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vein and the meningeal

branch of occipital artery.
NORMA OCCIPITALIS

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ATTACHMENTS:
1. External occipital protuberance:
a) Upper part gives origin to the trapezius
b) Lower part gives attachment to upper end of the ligamentum nuchae.
2. Superior nuchal lines:

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a) Medial 1/3- gives origin to trapezius.
b) Lateral part provides insertion to sternocleidomastoid above and splenius

capitis below.

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3. Highest nuchal lines: (if present)
a) Provides attachment to epicranial aponeurosis medially.
b) Gives origin to occipitalis or occipital belly of occipitofrontalis muscle laterally.
* In case the highest nuchal lines are absent, these structures are attached to the

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superior nuchal lines.


NORMA OCCIPITALIS

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Epicranial aponeurosis

Occipital belly of occipitofrontalis

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muscle.