norma basalis or inferior view of skull mant with bone discribtion

1. Norma basalis (skull base)Norma basalis (skull base)
Dr kifayat khan
o Mphil Anatomy
o IBMS KMU
o Kaif_ayubian@hotmail.com

2. ObjectivesObjectives
To identifies the bones of
the skull base (inferior
view) as well as their
boundaries.
To know the important
anatomic structures
passing in and out of base
of skull

3. BoundriesBoundries
 bounded in front by the incisor
teeth in the maxillæ.
 laterally by the alveolar arch,
the lower border of the
zygomatic bone, the zygomatic
arch and an imaginary line
extending from it to the
mastoid process and extremity
of the superior nuchal line of
the occipital.

4. Base of skull is formed by
the following bones
1) Hard palate formed by Palatine
processes of the maxillæ and
palatine bones
2) The vomer
3) Sphnoid bone with
I. the pterygoid processes
II. the under surfaces of the
great wings
III. spinous processes
4) Temporal bone with squamæ
and mastoid and petrous
portions
5) Occipital bone

5. 1)Hard palate1)Hard palate
 Bounded in front and laterally
by the alveolar arch
 Has two bones,palatine process
of maxilla and palatine bone
 Two palatine process of
maxilla are joined by median
palatine suture
 And with palatine bone by
transverse palatine suture
 Posterior most limit is posterior
nasal spine

6. ForamenForamen
 behind the incisor teeth is the
incisive foramen
 Posteriorolatrally is the
greater palatine foramen, for
the transmission of the
descending palatine vessels
and anterior palatine nerve
 Behind is lesser palatine
foramina

7. 2) vomer2) vomer
 Above the hard palate are the
choanæ (posterior nasal
apertures ) separated by the
vomer.
 Each is bounded above by the
body of the sphenoid, below
by the horizontal part of the
palatine bone, and laterally by
the medial pterygoid plate of
the sphenoid.
 At the superior border of the
vomer may be seen the
expanded alæ of this bone

8. 3)Sphenoid bone3)Sphenoid bone
 It has
 Lateral and medial pterygoid
process
 The under surfaces of the great
wings
 Lateral to medial plate is
scaphoid fossa, for the origin of
the Tensor veli palatini, and at
its lower extremity the
hamulus, around which the
tendon of this muscle turns.
 The lateral pterygoid plate
forms the medial boundary of
the infratemporal fossa.

9.  The great wing of
sphenoid bone have 3
foramens
I. Foramen ovale
II. Foramen spinosum
III. Foramen Rotendum
i) Foramen Ovale
 Located at the base of the lateral
pterygoid plate
 Transmit
1. Mandibular Nerve (CN V3)
2. Accessory meningeal nerve
3. Lesser petrosal nerve
4. Emissary vein (Cavernous sinus to
pterygoid plexus)

10. ii) Foramen spinosum
 It is an aperture in the
greater wing of the
sphenoid posterolateral to
foramen ovale.
 Transmit :-
1. Middle meningeal artery &
vein.
2. Emissary vein.
3. Nervous spinosus
(Meningeal branch of
mandibular nerve)

11. iii) Foramen rotendum
Is actually a canal in the base of the
greater sphenoid wing, is situated
just inferior and lateral to the
superior orbital fissure.
The canal transmits the maxillary
nerve ( V2) and emissary veins.

12. iv) Foramen Lacerum
It is located at the base of medial
pterygoid plate, at the junction of
sphenoid ,petrous temporal apex,
medially by basilar portion of the
occipital bone
Structures passing whole length
 Meningeal branch of Ascending
pharyngeal artery
 Emissary vein
Other structures partially traversing
 Internal carotid artery
 Greater petrosal nerve.

13.  Petrous part of temporal bone has
 carotid canal for ICA and
sympathetic plexus.
 Its apex forms boundary of
foramen lacerum
 Medial to the styloid process,its
petrous part overlay the jugular
foramen.
 Jugular foramen
 transmits inferior petrosal sinus
 the glossopharyngeal
 Vagus nerve
 accessory nerves
 the transverse sinus

14. 5) Occipital bone5) Occipital bone
 Behind the nasal cavities is the
basilar portion of the occipital
bone, with pharyngeal tubercle
 The foramen magnum
 Located behind basi-occipit
bounded laterally by the
occipital condyles
 transmits the medulla
oblongata
 the accessory nerves
 the vertebral arteries
 the anterior and posterior
spinal arteries

15.  The occipital condyles lies lateral to
foramen magnum
 They articulate with the atlas.
 hypoglossal canal
 Located Superior to the occipital
condyle
 Transmission hypoglossal nerve
 meningeal artery.
 Behind the foramen magnum is the
external occipital crest ending
above at the external occipital
protuberance, while on either side
are the superior and inferior
nuchal line

17. ReferencesReferences
1. Imaging of skull base: Pictorial essay Abhijit A Raut , Prashant S Naphade,
and Ashish Chawla. Indian J Radiol Imaging. 2012 Oct­Dec; 22(4): 305–316.
2. Imaging of the Anterior Skull Base :Hemant Parmar,MD, SachinGujar,MD et.al.
Neuroimag Clin N Am 19 (2009) 427–439.
3. CT and MR Imaging of the Central Skul Base. Part 1: Techniques, Embryologic
Development, and Anatomy. Fredj Lame, MD, Lyn Nadel, MD, Ira F. Braun, MD.
RadloGraphics 190; 10:59 1­602
4. Imaging of the Central Skull Base Alexandra Borges, MD. Neuroimaging Clinics
of North America Volume 19, Issue 3, August 2009, Pages 441–468.
5. Skull base embryology: a multidisciplinary review. Di Ieva A1, Bruner E, Haider T
et.al Childs Nerv Syst. 2014 Jun;30(6):991­1000.
6. Som and curtin.
7. http://www.med.wayne.edu/diagRadiology/Anatomy_Modules/axialpages/O
verview.html