Download Neurocranium - ugur baran kasirga web pages

Neurocranium
Bones of the cranium (skull) are studied in two
groups:
• Bones of the NEUROCRANIUM- Bones which enclose and protect the
brain.
• Bones of the SPLANCHNOCRANIUM (VISCEROCRANIUM)- Bones
which form the facial skeleton. They surround at the same time the
oral , nasal and orbital cavities and form boundaries around the deep
structures of the face.
• This division is actually arbitrary as there is an overlap between these
two groups in the formation of certain parts of the skull.
BONES OF THE NEUROCRANIUM
• TEMPORAL BONES (PAIRED)
• SPHENOID BONE (SINGLE)
• FRONTAL BONE (SINGLE)
• OCCIPITAL BONE (SINGLE)
• PARIETAL BONES (PAIRED)
TEMPORAL BONES
• Take place one on each side of the skull.
• The temporal bones take part in the formation of the
sides and base of skull.
• Each temporal bone has several parts:
a) Squama (leaf)
b) Tympanic
c) Petromastoid which can be divided into a petrous
(pyramis) part and a mastoid part.
TEMPORAL BONE
TYMPANIC PART & SQUAMA
INNER SURFACE OF SQUAMA
MASTOID PART
• It forms the posterior part of the bone.
• Mastoid foramen.
• Mastoid process.
• Mastoid notch.
• Groove (sulcus) for the occipital artery.
• Groove for sigmoid sinus.
• Mastoid air cells (antrum).
PETROUS PART (PYRAMIS)
• It lies at the base of the skull between the sphenoid and occipital
bones. It is directed medially, forwards and slightly upwards.
• It has an apex and three surfaces: superior (anterior),posterior,
inferior.
APEX
KEY WORDS:
• TRIGEMINAL IMPRESSION.
Contains the trigeminal
(Gasserian) ganglion.
• INTERNAL APERTURE OF THE
CAROTID CANAL. Transmits the
internal carotid artery.
SUPERIOR (ANTERIOR) SURFACE
KEY WORDS:
ARCUATE EMINENCE
TEGMEN TYMPANI
HIATUS FOR FACIAL CANAL
GROOVE (SULCUS) FOR GREATER PETROSAL NERVE
GROOVE FOR LESSER PETROSAL NERVE
POSTERIOR SURFACE
• KEY WORDS:
• INTERNAL AUDITORY MEATUS (APERTURE)
• EXTERNAL APERTURE (OPENING) OF AQUEDUCTUS VESTIBULI
• SUBARCUATE FOSSA
INFERIOR SURFACE
• KEY WORDS:
• EXTERNAL APERTURE OF THE CAROTID CANAL.
• MUSCULOTUBAL CANAL.
• JUGULAR FOSSA & JUGULAR NOTCH (INCISURE).
• STYLOID PROCESS.
• STYLOMASTOID FORAMEN (TRANSMITS THE FACIAL
NERVE)
THE SPHENOID BONE
• It is a single butterfly shaped bone located at the base
of the skull, anterior to the temporal bones and
basilar part of the occipital bone.
• It takes part in the formation of the sides and base of
skull as well as the orbital and nasal cavities.
• It consists of a body and a pair of greater and lesser
wings.
GREATER WINGS (ALAE)
• KEY WORDS:
• PTERYGOID PROCESS: Lateral and medial plates +
hamulus.
• PTERYGOID NOTCH.
• ANTERIOR & POSTERIOR ORIFICE (OPENING) OF THE
PTERYGOID CANAL.
GREATER WING
• Each greater wing has three surfaces:
• CEREBRAL SURFACE
• ORBITAL SURFACE
• LATERAL SURFACE
CEREBRAL SURFACE
KEY WORDS:
Anteromedially is the ROUND FORAMEN (ROTUNDUM)
which transmits the MAXILLARY nerve.
Posterolateral to the rotundum is the OVAL FOR. which
transmits the MANDIBULAR nerve & ACCESSORY
MENINGEAL artery (if present).
Adjacent to the oval for. is the FOR. SPINOSUM which
transmits the MIDDLE MENINGEAL artery and
MENINGEAL branch of the MANDIBULAR nerve.
LATERAL SURFACE
• This surface is divided by a transverse crest called the
INFRATEMPORAL CREST into a superior TEMPORAL
SURFACE and an inferior INFRATEMPORAL SURFACE.
• The lateral surface takes part in the formation of the
sides of the skull.
ORBITAL SURFACE
• This surface is directed anteriorly and medially and
forms the posterior part of the lateral wall of the
orbital cavity.
THE LESSER WINGS
They are two triangular plates which project from the
anterosuperior part of the body and end in sharp
points.
• It is connected to the body by two roots.
• Each lesser wing has an anterior border and a
posterior border.
• KEY WORDS:
• OPTIC CANAL (which transmits the OPTIC nerve &
OPHTHALMIC artery.
• ANTERIOR CLINOID PROCESS.
SUPERIOR ORBITAL FISSURE
• Leads from the cranial cavity into the orbital cavity.
• It is bounded medially by the body of the sphenoid; above by the
lesser wing, below by the orbital surface of the greater wing. Laterally
it is completed by the frontal bone.
THE BODY
• The body is cubical. Within the body is an air sinus called the
sphenoid sinus. It may be divided into two by a septum.
• KEY WORDS:
• CAROTID SULCUS.
• TUBERCULUM SELLAE.
• HYPOPHYSEAL FOSSA.
• DORSUM SELLAE. The three are collectively called the SELLAE
TURCICA.
• MIDDLE and POSTERIOR CLINOID PROCESSES.
• SPHENOIDAL CREST- ROSTRUM.
THE FRONTAL BONE
It is a single bone and it forms the skeleton of the forehead.
Parts of the frontal bone are:
1- Squama.
2- Orbital parts.
3- Nasal part.
FRONTAL SQUAMA
• It is a flat bone which is externally convex and internally concave.
• EXTERNAL SURFACE KEY WORDS:
Frontal tuber (tuberosity).
Temporal line.
Superciliary arches.
Glabella.
Supraorbital margin.This margin laterally ends as the zygomatic process. Medially
it contains a notch or foramen called the supraorbital notch or foramen.
• Within the squama are located the frontal sinuses.
•
•
•
•
•
FRONTAL SQUAMA INNER SURFACE
INTERNAL SURFACE KEY WORDS:
• Sulcus for superior sagittal sinus.
• Frontal crest
• Foramen caecum
METOPIC SUTURE
THE ORBITAL PARTS
• Consists of two lamınae separated by a wide notch called the
ETHMOİDAL NOTCH.
• Anterolaterally is a shallow fossa called FOSSA FOR THE LACRIMAL
GLAND.
• The ethmoidal notch is occupied in the articulated skull by the
cribriform lamina of the ethmoid bone.
• On the lateral margins of the notch are located several air cells.
• Anteriorly, lateral to the nasal spine, are the openings of the frontal
sinuses.
NASAL PART
• It is the smallest part of the bone.
• It projects downwards between
the supraorbital margins.
• It ends below in a sharp NASAL
SPINE.
THE OCCIPITAL BONE
• It is a single bone which forms a large part of the back
& base of skull.
• It consists of four parts which together enclose a large
foramen called the FORAMEN MAGNUM.
• The parts of the bone are:
Squama.
Two lateral parts.
Basilar part.
OCCIPITAL SQUAMA
• It is externally convex, internally concave.
• EXTERNAL SURFACE KEY WORDS:
• EXTERNAL OCCIPITAL PROTUBERANCE.
• EXTERNAL OCCIPITAL CREST.
• HIGHEST (SUPREME) NUCHAL LINE.
• SUPERIOR NUCHAL LINE.
• INFERIOR NUCHAL LINE.
SQUAMA
• INTERNAL SURFACE KEY WORDS:
• INTERNAL OCCIPITAL PROTUBERANCE.
• INTERNAL OCCIPITAL CREST.
• SULCUS (GROOVE) FOR SUPERIOR SAGITTAL SINUS.
• SULCUS (GROOVE) FOR TRANSVERSE SINUS.
LATERAL (CONDYLAR) PARTS
• They are located on each side of the foramen magnum.
• KEY WORDS:
• OCCIPITAL CONDYLES.
• HYPOGLOSSAL CANAL (above anterior part of condyle)
• CONDYLAR FOSSA (behind the condyle)
• JUGULAR PROCESS (extends laterally from the posterior half of the
condyle)
• JUGULAR NOTCH (in the anterior part of the jugular process)
THE BASILAR PART
• It forms the anterior part
of the bone and it is
quadrilateral in shape.
• On its inferior surface in
the middle is the
PHARYNGEAL TUBERCLE.
• The whole of its upper
surface is in the form of a
groove called the CLIVUS.
THE PARIETAL BONES
• The parietal bones form the vault of the skull and
part of the skeleton of the sides of the skull.
On the external surface:
• Each parietal bone is externally convex and
internally concave.
• PARIETAL TUBER (TUBEROSİTY).
• Each bone has four angles and four borders.
• SUPERIOR TEMPORAL LINE.
• Angles:
• INFERIOR TEMPORAL LINE.
FRONTAL (ANTEROSUPERIOR).
On the internal surface:
SPHENOIDAL (ANTEROINFERIOR).
OCCIPITAL (POSTEROSUPERIOR).
MASTOID (POSTEROINFERIOR).
• GROOVES(SULCI) FOR THE FRONTAL AND PARIETAL
BRANCHES OF THE MIDDLE MENINGEAL ARTERY.