Download MBBS (Bachelor of Medicine and Bachelor of Surgery) Latest 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:
? 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
? Maxilla
? Occipital bone
? Nasal bone
NORMA LATERALIS
? Important structures to be identified are:
1. Temporal lines
11.Mastoid foramen
2. Supra mastoid crest
12.Temporal fossa
3. Zygomatic arch
13.Styloid process
4. External auditory meatus 14.Infra temporal fossa
5. Squamo-tympanic suture 15.Pterygopalatine fossa
6. Supra meatal spine
16.Sphenopalatine foramen
7. Supra meatal triangle
17.Greater palatine canal
8. Parieto-mastoid suture
9. Occipito-mastoid suture
10.Mastoid process
NORMA LATERALIS
TEMPORAL FOSSA:
? Depressed area below the temporal lines.
? Boundaries:
?Anteriorly:
i. Temporal surface of zygomatic process of frontal.
ii. Frontal process of zygomatic.
iii. Greater wing of sphenoid.
?Posteriorly:
i. Posterior part of superior temporal line.
ii. Supra mastoid crest.
?Superiorly: superior temporal line.
?Inferiorly:
i. Laterally: zygomatic arch.
ii. Medially: infratemporal crest.
?Floor gives origin to temporalis muscle.
NORMA LATERALIS
TEMPORAL FOSSA
? Contents:
1. Temporalis muscle
with its fascia.
2. Two deep temporal
nerves.
3. Temporal branches
of maxillary artery.
4. Zygomatico-
temporal nerves.
NORMA LATERALIS
INFRA TEMPORAL FOSSA
? Irregular space situated behind the maxilla and below the zygomatic arch.
? Boundaries:
?Medially:
i. Lateral pterygoid plate.
ii. Pyramidal process of palatine bone
?Anteriorly:
i. Posterior surface of maxilla.
ii. Medial surface of zygomatic bone.
?Roof:
i. Infra temporal surface of greater wing to sphenoid.
ii. Squamous part of temporal bone.
NORMA LATERALIS
INFRA TEMPORAL FOSSA:
?Above it communicates with temporal fossa.
?It is open on its posterior, lateral and inferior aspects.
?Laterally ramus of mandible forms its boundary.
?Anterior and medial walls are separated in the upper
part by pterygomaxillary fissure, while they meet below.
?Through pterygomaxillary fissure, this fossa
communicates with the pterygopalatine fossa.
NORMA LATERALIS
INFRA TEMPORAL FOSSA:
? Contents:
1. Muscles:
a) Lateral pterygoid
b) Medial pterygoid
2. Nerves:
a) Mandibular and its branches
b) Corda tympani
c) Maxillary
3. Vessels:
a) Maxillary artery and its branches
b) Middle meningeal artery
c) Maxillary vein.
d) Pterygoid plexus of veins.
NORMA LATERALIS
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
sphenoid.
?Medially: upper part of lateral surface of perpendicular plate of palatine bone
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
pterygomaxillary fissure.
NORMA LATERALIS
PTERYGOPALATINE FOSSA:
? Communications:
?5 Openings and 2 fissures in this fossa.
?3 openings in the posterior wall. They are:
1. Foramen rotendum
2. Pterygoid canal
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.
?Fissures are: pterygomaxillary fissure and inferior orbital fissure.
NORMA LATERALIS
PTERYGOPALATINE FOSSA:
? 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.
5. Nasal cavity through sphenopalatine foramen.
6. Roof of oral cavity through greater palatine foramen.
NORMA LATERALIS
PTERYGOPALATINE FOSSA:
?Contents:
1. Maxillary artery and its branches.
2. Maxillary nerve in its course to the orbit. The
nerve enters the fossa through foramen rotendum.
3. Pterygopalatine/sphenopalatine ganglion with its
branches ( orbital, palatine, nasal and pharyngeal)
4. Pterygoid nerve.
NORMA OCCIPITALIS
NORMA OCCIPITALIS
?Norma occipitalis is convex upwards and on each
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
below.
3. Mastoid part of the temporal bone, on each side.
NORMA OCCIPITALIS
?Sutures seen are:
1. LAMBDOID SUTURE: between the occipital and two
parietal bones.
2. OCCIPITO MASTOID SUTURE: between the occipital
and mastoid part of temporal bone.
3. PARIETOMASTOID SUTURE: between the parietal bone
and mastoid part of temporal bone.
4. SAGITTAL SUTURE: the posterior part is also seen.
NORMA OCCIPITALIS
EXTERNAL OCCIPITAL
PROTUBERANCE:
? Is a median prominence
in the lower part of this
norma.
? It marks the junction of
the head and the neck.
? The most prominent
point on this
protuberance is called
the inion.
NORMA OCCIPITALIS
SUPERIOR NUCHAL
LINES:
? Are curved bony
ridges passing
laterally from the
protuberance.
?These also mark
the junction of the
head and the neck.
NORMA OCCIPITALIS
HIGHEST NUCHAL LINES:
? Are not always present.
? They are curved bony
ridges situated 1 cm
above the superior
nuchal lines.
? They begin from the
upper part of the
external occipital
protuberance.
? Are more arched than
the superior nuchal lines.
NORMA OCCIPITALIS
OCCIPITAL POINT:
?It is a median
point a little
above the inion.
?It is the point
farthest from the
glabella.
NORMA OCCIPITALIS
THE MASTOID FORAMEN:
? Located on the mastoid
part of temporal bone at
or near the
occipitomastoid suture.
? Internally, it opens at the
sigmoid sulcus.
? The mastoid foramen
transmits an emissary
vein and the meningeal
branch of occipital artery.
NORMA OCCIPITALIS
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:
a) Medial 1/3- gives origin to trapezius.
b) Lateral part provides insertion to sternocleidomastoid above and splenius
capitis below.
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
superior nuchal lines.
NORMA OCCIPITALIS
Epicranial aponeurosis
Occipital belly of occipitofrontalis
muscle.
This post was last modified on 30 November 2021