Temporal: It is an important bone because
·
Whole internal ear
·
Whole middle ear
·
Bony part of external
auditory meatus lies within it .
SN: Only cartilaginous part of external
auditory meatus and auricle lies outside the temporal bone
1.
Anatomical point :
·
Convex squamous part
is directed laterally
·
Apex of petrous part
is directed medially , forward, and upward
·
Zygomatic process is
directed anteriorly
2.
Morphological type : pneumatic
irregular bone
3.
Ossification : both intramembranous and intracartilaginous
·
Squmous part and
tympanic part is ossify from membrane
·
Rest of the temporal
bone is ossify from cartilage
4.
Development :
Petrous part of temporal bone is derived from paraxial mesoderm
Rest of the part of temporal bone is derived from neural
crest
5. Parts: It has
Three parts:
i.
Squamous part
ii.
Petro-mastoid part
iii.
Tympanic part
Three processes:
It has three processes
:
i.
Zygomatic process
ii.
Mastoid process
iii.
Styloid process
Squamous part : it has two surfaces
External
surface:
i)
whole external surface is attached by origin of temporalis
muscle except mandibular fossa and zygomatic process
ii)
external surface
bears groove for middle temporal artery
iii)
Suprameatal triangle
: this triangle situated just above and posterior part of the external auditory meatus
iv)
Importance of
suprameatal triangle : mastoid antrum lies 1.25 cm deep to it
Internal
surface:
Impressions of temporal lobe of cerebrum
Groove for middle meningeal artery
Squamous part has two borders
·
Superior border
articulate with inferior border of parietal bone
·
Antero-inferior
border : articulate with greater wing of sphenoid bone
Petrous
part: It has
Apex: is
directed medially, forward and upwards
Base: attached
with squamous and mastoid part
Petrous
part : 3 borders:
1. Anterior border: articulate with greater wing of sphenoid
2. Superior border: lodges superior
petrosal sinus and attachment of tentorium cerebella except medial part
3. Posterior border:
Medial part of posterior border is lodge by inferior petrosal sinus and
Lateral part of posterior border forms jugular foramen by articulating with
condylar part of occipital bone
3
surfaces of petrous part : anterior, posterior and inferior
Anterior surface of
petrous part :
1.
This surface is irregular for sulci and gyri of temporal lobe of
cerebrum
2. Trigeminal impression
( a depressed area near the apex ): lodge trigeminal ganglion
3. Arcuate eminence: an elevated area behind the trigeminal impression, it is
caused by superior semicircular canal of internal ear
4.
Tegmen tympani: a thin plate of bone situated in between arcuate eminence
and squamous part of temporal bone.
From antero- posteriorly , tegment
tympani forms
1. Roof of tensor tympani
2. Roof of middle ear cavity
3. Roof of mastoid antrum
Posterior surface of
petrous part of temporal bone:
Bear orifice of internal auditory meatus : Structure
passing through the foramen
Structures entrance into internal
auditory meatus :
·
Motor root of facial
nerve
·
Labyrinthine artery
Structures exit from the internal
auditory meatus:
·
sensory root of
facial nerve
·
vestibulocochlear
nerve
·
labyrinthine vein
Inferior surface of petrous part of temporal bone:
From antero
posteriorly
1.
Near apex: attachment of levator veli palatine muscle and
cartilaginous part of auditory tube
2.
External or lower opening of carotid canal
3.
Jugular fossa
Mastoid
part
It forms the posterior part of temporal
bone
It has
Two surfaces: external and internal
Two borders: superior and posterior
1 process: mastoid process
External surface of mastoid part
It is attached with following muscles :
muscles are arrange from above , downwards and forwards
i.
Auricularis posterior
ii.
Origin of occipital
belly of occipito frontalis muscle
iii.
Insertion of
sternocleidomastoid
iv.
Insertion of splenius
capitis
v.
Insertion of
longissimus capitis
internal surface of mastoid part
Sigmoid sulcus : a deep groove which lodge sigmoid sinus
Two
borders of mastoid part :
·
superior border
articulate with inferior border of parietal bone
·
posterior border
articulate with inferior border of squamous part of occipital bone
Tympanic part
·
A thin plate of bone
lies between the squamous and mastoid parts
·
Anterior surface form
non articular part of mandibular fossa
·
Posterior surface
forms greater part of external auditory meatus
Processes of temporal bone
i.
Zygomatic process :
·
medial surface and
lower border of zygomatic process give origin of masseter muscle
·
Superior border of
zygomatic process attached with temporal fascia
·
Anterior end of
zygomatic process articulate with temporal process of zygomatic bone
ii.
Mastoid process :
External surface of mastoid process is attached with
a) Insertion of sternocleidomastoid
b) Insertion of splenius capitis
c) Insertion of longissimus capitis
Mastoid notch : a
deep notch at the medial surface of mastoid process gives origin of posterior
belly of digastric muscle
Mastoid foramen near
the posterior border of mastoid part of temporal bone : it transmit an emissary
vein which connect sigmoid sinus with posterior auricular vein
iii.
Styloid process
Muscles :
·
origin of styloglossus,
stylohyoid and stylopharyngeus
Ligaments :
·
stylohyoid and stylomandibular ligament
Stylomastoid foramen :
·
It is situated in
between mastoid process and styloid process
It transmitted
·
Facial nerve exit
·
Entrance stylomastoid
branch of posterior auricular artery
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