Temporal bone anatomy and surgical significancepptx
1. SURGICAL ANATOMY OF TEMPORAL BONE,
LATERAL SKULL BASE, VENOUS SINUSES AND
DIFFERENCE IN TEMPORAL BONE OF ADULT
AND CHILDREN
Dr. Ravi Swar
1ST Year Resident
M.S.ENT-HEAD AND NECK SURGERY
2. ROADMAP
SURGICAL ANATOMY OF TEMPORAL BONE
- EXTERNAL ANATOMY OF TEMPORAL BONE
- VASCULAR ANATOMY
- SURGICAL LANDMARKS
LATERAL SKULL BASE
- DIVISION OF SKULL BASE
- SPHENOID BONE
- SUBDIVISIONS OF LATERAL SKULL BASE
- LATERL SKULL BASE APPROACHES
DIFFERENCE IN TEMPORAL BONE OF ADULT AND CHILDREN
VENOUS SINUSES
- INTRODUCTION
- FUNCTION
- TYPES
6. EXTERNAL ANATOMY OF TEMPORAL
BONE
A. LATERAL SURFACE
Encountered for operative procedure or
during laboratory drilling
Tip of mastoid process:
postauricular incisions
Zygomatic process
- Origin- anterior to External auditory
canal
- Extent- Posterior zygomatic tubercle
Glenoid fossa Anterior
Zygomatic tubercle
Zygomatic bone
7. EXTERNAL ANATOMY OF TEMPORAL
BONE(lateral surface continue…………)
Temporal line/ Linea temporalis
- Posteriorly and superiorly from root of Zygoma
- Inferior border of Temporalis muscle
- Floor of middle cranial fossa
- Superiorly - Squamous portion
Inferiorly and anteriorly - tympanic ring
Posteriorly - Mastoid
-Avascular plane - postauricular approach
Digastric groove/Mastoid incisura
Posterior and medial to mastoid tip
Cleft for posterior belly of Digastric
8. EXTERNAL ANATOMY OF TEMPORAL
BONE(lateral surface continue………..)
Tympanomastoid fissure
Anterior to tip of Mastoid
Traced medially to Stylomastoid foramen-
exit point of facial nerve
TMS and TSS
- landmark for vascular strip incision used in tympanomastoid sx
- Elevation of EAC skin and periosteum – requires sharp dissections
Petrotympanic suture
- Traversed by : Chorda tympani nerve
Ant Process of malleus
Ant tympanic artery
9. EXTERNAL ANATOMY OF TEMPORAL BONE(lateral
surface continue…………….)
Spine of Henle/Suprameatal spine
- prominence at posterosuperior rim of EAC
- Marks ant. Limit of dissection in canal wall up
mastoidectomy
- Localizes imp strs during skull base sx
- Distance from Henle’s spine to
ALONG SPINOPTERYGOID LINE
•Spine of Sphenoid= 3cm
•Foramen Spinosum= 3.5cm
•Foramen Ovale
Ant margin= 4cm
Post margin= 4.5cm
ALONG BISPINAL LINE
•Stylomastoid foramen= 1.5cm
•Jugular foramen
Lateral margin= 2.5 cm
Medial margin= 3.5cm
•External orifice of Hypoglossal
canal= 4cm
•Foramen magnum= 5cm
10. EXTERNAL ANATOMY OF TEMPORAL
BONE(lateral surface continue……….)
Korner’s/Petrosquamous septum
-petrosquamosal suture persisting as a
bony plate
-separates superficial squamosal cells
from the deep petrosal cells
-causes difficulty in locating antrum and
deeper cells during mastoid surgery
leading to incomplete removal of disease
11. EXTERNAL ANATOMY OF TEMPORAL BONE(lateral
surface continue………)
MACEWEN’S TRIANGLE
- Suprameataltriangle/suprameatal pit/
mastoid fossa/ foveola suprameatica/
fossa mastoidea
- Laterally overlies mastoid antrum : 1.5-
2cm deep
- Boundary:
Superiorly- Temporal line/ posterior
root of zygomatic arch
Posteriorly- Tangent to post.
EAC
In front and below- upper
margin of the meatus
12. EXTERNAL ANATOMY OF TEMPORAL
BONE(lateral surface continue………)
- Identified by- numerous perforating small vessels-
Cribose/ Cribriform area
- Important landmark when performing a cortical
mastoidectomy
- Present even in least pneumatized temporal bones:
mastoid drilling commences at this site
13. EXTERNAL ANATOMY OF TEMPORAL BONE
B. SUPERIOR SURFACE / TEGMEN
Floor of the middle cranial fossa
Separates tympanomastoid compartment from temporal lobe
Divided into
Anterior: Tegmen tympani Posterior: Tegmen mastoideum
-covers tympanic cavity -covers mastoid air cells
Petrotympanic suture line forms medial boundary of tegmen
Petrous – ”rocklike”
- forms superior,medial and posterior part of
temporal bone
- marked by depressions and eminence
corresponding to convolutions of brain
and internal structures of temporal bone
14. EXTERNAL ANATOMY OF TEMPORAL
BONE(SUPERIOR SURFACE)
Landmarks:
1. Arcuate eminence
-approximates position of superior
semicircular canal
2. Meatal plane
-indicates internal auditory canal
3. Tympanic canaliculi
-lesser superficial Petrosal nerve
4. Facial hiatus
-Greater superficial Petrosal nerve
15. EXTERNAL ANATOMY OF TEMPORAL
BONE(SUPERIOR SURFACE)
6. Foramen lacerum
Boundary:
Infront- greater wings of
Sphenoid
Behind- Petrous apex
Medially- basilar part of
Occiput
Closed by dense
fibrocartilage
16. • Transmits :
1. Ascending pharyngeal artery –meningeal
branch
2. Nerve of pterygoid canal
7. Surgical landmark for ant limit of temporal
bone:
a. Foramen Ovale- mandibular div. of
Trigeminal nerve
17. EXTERNAL ANATOMY OF TEMPORAL BONE
a. Foramen Spinosum-
1.Middle meningeal vessels
2. Recurrent branch of
mandibular nerve
C) POSTERIOR SURFACE
Forms anterior border of
posterior cranial fossa
Sigmoid sulcus-
accommodates sigmoid sinus
Foveate fossa- for intradural
portion of endolymphatic sac
18. EXTERNAL ANATOMY OF TEMPORAL
BONE(POSTERIOR SURFACE)
Superior petrosal sulcus
- at interface of posterior and
middle cranial fossa plates of
temporal bone
- carries superior petrosal
sinus from sigmoid sinus to
cavernous sinus anteriorly
Internal auditory canal
Fig: cross section of IAC
19. EXTERNAL ANATOMY OF TEMPORAL BONE
D) INFERIOR SURFACE
Separates upper neck from
skull base
External carotid foramen -
internal carotid artery
Jugulocarotid crest
- Separates carotid canal from
jugular foramen
-Traversed by inferior tympanic
canaliculus carrying 1.inferior
tympanic artery
2.Jacobson’s nerve
20. EXTERNAL ANATOMY OF TEMPORAL BONE (INFERIOR SURFACE)
Cochlear aqueduct:
- encountered when drilling medial to jugular bulb
- translabyrinthine cerebellopontine angle tumor surgery
opening flow of CSF into mastoid decompresses
CSF pressure.
-CN. IX,
inferior petrosal sinus
some cases, CN. X and XI
-inflammatory cells reach basal turn of scala tympani from
subarachnoid space through patent cochlear aqueduct
immediatel
y inferior to
lateral
terminus of
cochlear
aqueduct.
used as guide to
lower limit of IAC
dissection
without risking
lower cranial
nerves.
21. EXTERNAL ANATOMY OF TEMPORAL
BONE (INFERIOR SURFACE)
Stylomastoid foramen facial nerve
Digastric groove Medial to mastoid tip
For posterior belly of
Digastric
22. EXTERNAL ANATOMY OF TEMPORAL BONE
ANTERIOR SURFACE
Petrous apex separates
greater wing of sphenoid
from occipital bone
Prominent features:
1. Internal carotid
foramen- carotid artery
exits temporal bone
2. Impression for trigeminal
ganglion-on lateral surface
of petrous apex.
23. EXTERNAL ANATOMY OF TEMPORAL
BONE(ANTERIOR SURFACE)
3. Semicanal for tensor tympani-lateral to carotid canal
4. Bony portion of eustachian tube
- inferior and parallel to tensor tympani
- medial wall forms lateral wall of carotid canal,frequently
dehiscent carotid canal vulnerable to injury
during surgical manipulations
24. VASCULAR ANATOMY
A. Temporal Bone Arteries
ICA
-External carotid foramen
Superiorly until It encounters
cochlea 90 degree bend
-Anterior and medial to ET
Internal Carotid formen
-Throughout intrapetrous
course accompany venous
and neural plexus
25. VASCULAR ANATOMY (Temporal Bone
Arteries)
Clinical correlation:
Bony shell protecting artery
- thin(often less than 0.5 mm thick) dehiscent in 6% of
cases
- potential for injuring ICA during surgery for
COM or Cholesteatoma
Aberrant carotid artery-artery follows an anomalous
course lateral and posterior to vestibular line
Anterior inferior cerebellar artery (AICA) often extends a
loop into ICA Disruption of AICA causes hemorrhage
and infarction of labyrinth and brainstem
26. VASCULAR ANATOMY
B. Temporal Bone Veins
3 dominant sinuses of temporal bone are
- Sigmoid (portion of the lateral venous sinus)
- Superior petrosal
- Inferior petrosal
Sigmoid sinus
-Location: S-shaped sulcus in the posterior
mastoid—hence term “sigmoid”
-Forms post boundary of mastoid cavity but in well
pneumatized bones- accessory air cells extend beyond
sigmoid sinus
27. VASCULAR ANATOMY (Temporal Bone
Veins)
- Direct continuation of
Transverse sinus {Rt larger
than left (75% cases)} Angle
of Citelli: angle between
sigmoid sinus/posterior
cranial fossa dura and middle
cranial fossa dura runs
inferiorly and medially
rises to jugular bulb
28. VASCULAR ANATOMY (Temporal BoneVeins)
Jugular bulb
Interposed between the sigmoid sinus and internal jugular
vein
Sigmoid sinus Bulb
- thick wall -thin wall
- readily contracts -doesnot
with cautery manipulation
- venous hemorrhage controlled
with pressure applied via Gelfoam
surmounted by neurosurgical
cottonoid
Position
- Variable relative to facial nerve and it’s penetration into
tympanic cavity
29. VASCULAR ANATOMY (Temporal
BoneVeins)
- High-riding jugular bulb:
extends to or above inferior tympanic annulus
alternate definition-one encroaching to within 2 mm or less on inferior
aspect of IAC.
in 3.5 to 5% of temporal bone specimens
frequently on right side
Surgical significance-
1. may mimic middle ear vascular mass eg. Glomus tympanicum source
of hemorrhage in tympanostomy tube insertion
2. Jugular bulbs reaching as high as superior aspect of IAC renders
exposure of IAC
33. Divisions of skull base
1. Anterior
2. Central
3. Lateral
4. Posterior
Central and lateral divided by
parasagital line from medial
pterygoid to occipital condyle
Middle
34. INTRODUCTION OF LATERAL SKULL
BASE
Location- between anterior and posterior skull base
Boundary- Post. -occipital bone
Ant. -anterior border of sphenoid
and Zygomatic arch
Includes- undersurface of Sphenoid and temporal
with Zygomatic process
35. SPHENOID BONE
Parts:
greater wing of
sphenoid
medial pterygoid plate
lateral pterygoid plate
Greater wing of
sphenoid
articulates with
squamous temporal
bone forming roof of
infratemporal fossa
36. SPHENOID BONE
Relations:
Medially - petrous bone
with:
foramen ovale
anteriorly
foramen spinosum
posteriorly
In front- pterygoid plates
Behind- spine of sphenoid
38. SUBDIVISIONS OF LATERAL SKULL BASE
1. PHARYNGEAL AREA
Centrally in skull base
Roof of nasopharynx
Pharyngobasilar fascia
- rigid membrane through
which pharyngeal
constrictor muscles are
attached up to base of
skull making wall of
nasopharynx
- separated from
prevertebral muscles by
prevertebral fascia
39. BASE (PHARYNGEAL AREA)
On each side, origin of paratubal muscles -
Levator palati medially (within pharynx)
-tensor palati laterally (outside pharynx)
- partly attached to tube
- open it during swallowing
40. SUBDIVISIONS OF LATERAL SKULL
BASE (PHARYNGEAL AREA)
Fossa of Rosenmuller
- Location- above & behind medial end ET
- lateral recess of nasopharynx
- Depth- 2.5 cm
- apex of petrous bones and foramen lacerum lies here
Origin of levator palati muscle : intrapharyngeal
Nasopharyngeal carcinoma : may invade upwards
through foramen lacerum lateral rectus palsy by
compressing C N.6
41. SUBDIVISIONS OF LATERAL SKULL
BASE
2. TUBAL AREA
lateral to pharyngeal area
comprises region occupied by
Eustachian tube
Salpingopharyngeus muscle
Origin- posterior margin of the
tubal orifice
Insertion- posterior border of
thyroid cartilage and adjacent
pharyngeal wall
Supplied by- pharyngeal branch
of vagus
Function- contraction opens
tube
42. SUBDIVISIONS OF LATERAL SKULL
BASE (TUBAL AREA)
Course
Bony part- tapers down from anterior part of middle ear
( 1cm) upto isthmus
- Isthmus- junction of bony and cartilaginous
- narrowest part
- lies medial to spine of sphenoid
Cartilaginous part- runs forwards and medially at 45° and
( 2cm) downward at 30° opens into
nasopharynx
43. SUBDIVISIONS OF LATERAL SKULL
BASE
3. NEUROVASCULAR AREA
Important structures are:
Carotid sheath & its contents
Styloid apparatus
Facial Nerve
44. SUBDIVISIONS OF LATERAL SKULL
BASE (NEUROVASCULAR AREA)
A) CAROTID SHEATH
Compact network of aerolar tissue
Carotid canal to arch of aorta
Encloses : ICA above & CCA below
Vagus nerve
Carotid Canal : ICA & Carotid plexus of
sympathetic nerves
45. JUGULAR FORAMEN :Three compartments
www.nayyarENT.com 45
Compartmens Contents ( lateral
to medial )
Anterior * IX Nerve
* Inferior petrosal
Sinus
Middle * XI Nerve
* X Nerve
Posterior * IJV
SUBDIVISIONS OF LATERAL SKULL BASE
(NEUROVASCULAR AREA)
47. SUBDIVISIONS OF LATERAL SKULL BASE
(NEUROVASCULAR AREA)
B) STYLOID APPARATUS
Bone- Styloid bone
Ligaments- Stylohyoid
Stylomandibular
Muscles-
Muscles Origin(pa
rt of
Styloid)
Nerve
supply
Functio
n
1.Styloph
aryngeus
Deep
aspect of
base
CN IX Elevates
larynx
,pharynx
2.Stylohy
oid
Back of
base
CN VII Elevates
+retracts
hyoid
3.Stylogl
ossus
Front of
SP +SL
CN XII Retracts
tongue
48. C) FACIAL NERVE
Arise from Stylomastoid
Foramen
Branches:
i) Post auricular nerve
ii) Digastric branch
iii) Temporofacial branch
iv) Cervicofacial branch
www.nayyarENT.com 48
49. SUBDIVISIONS OF LATERAL SKULL
BASE
4) AUDITORY AREA
anterolateral to
neurovascular area
comprises steeply sloping
face of tympanic bone
Petrotympanic fissure of Glaser
- Lies at anteromedial edge
- transmits :1. chorda tympani
2. anterior tympanic branch of
maxillary artery
3.corresponding veins
draining into pterygoid plexus
50. SUBDIVISIONS OF LATERAL SKULL
BASE
5) ARTICULAR AREA
In front of auditory area
Includes Surface on which head of mandible
articulates
Boundary:
Anteriorly- attachment of joint capsule
Posteriorly - squamotympanic fissure
Medially and laterally- margins of mandibular fossa
51. SUBDIVISIONS OF LATERAL SKULL
BASE
6) INFRATEMPORAL FOSSA
Location :- below middle cranial fossa
- between ramus of mandible
and lateral wall of pharynx
Boundary:
Roof- greater wing of Sphenoid+Squamous
temporal bone( small portion post.)
Floor- absent - continues down into neck
Ant.- Post. wall of maxilla with
pterygomaxillary and infraorbital fissures
Post.- Carotid sheath+ styloid apparatus
Medially- Medial Pterygoid muscle +
InterPterygoid fascia
Laterally- mandible
52. SUBDIVISIONS OF LATERAL SKULL
BASE(INFRATEMPORAL FOSSA)
Contents:
Med & Lat Pterygoid M
Maxillary A
Maxillary V
Pterygoid Venous Plexus
Br of Mandibular N
53. LSB approaches
Temporal bone resections
Fisch approaches for glomus tumours
Labyrinthectomy
Translabyrinthine approaches for CP angle/IAC tumors
(Vestibular schwannoma)
Lateral approaches to Infra Temporal Fossa
Petrous apicectomy
55. IMPORTANCE
Contemplation of operative intervention in pediatric
patient
eg- during cochlear implantation in child Cochlear
wires, if reaching to lateral skull, placed with approx 2.5
cm of slack to accommodate anticipated growth.
dimensions that shows continuous growth in
teenage :
- depth of tympanic cavity
- length, width and depth of mastoid
facial recess should be adult size at birth.
56. In comparison with that of adult, in
neonates:
1) Squama - disproportionately large
2) Mastoid process
- nonexistent
-facial nerve exits stylomastoid
foramen emerge on lateral
aspect of skull vulnerable to
injury during standard
postauricular incision
- Incision- more post. or horizontal
3) Tympanic bone - relatively flat
ring, rather than cylinder
4) Position of entire temporal bone-
inferolateral and more lateral
orientation
57. Postnatal Development of the
Temporal Bone Neonate- flat tympanic ring and exposed
stylomastoid foramen
Infant <1 yr- notch of
Rivinus and foramen of
Huschke are becoming
evident.
Adolescent-tympanic ring extends
laterally completing formation of
bony EAC, sheath of styloid process
and nonarticular part of glenoid
fossa
Infant-1 yr:
opposing spurs of growing bone
at ventral aspect of bony EAC
fuse dividing original into adult
EAC and foramen of Huschke.
58. Postnatal Development of the
Temporal Bone
After 1 yrs of age:
mastoid continues to grow for up to 19 years
mastoid process- develop both laterally and inferiorly
mastoid tip- derived from petrous portion of mastoid
tympanic ring- extends laterally carries tympanic
membrane from horizontal orientation to angulation
by age 4 or 5 years.
59. Postnatal Development of the
Temporal Bone
lateral aspect of temporal bone is vertically oriented -
facial nerve buried beneath mastoid process
Antrum approximates that of adult by birth
but mesenchymal resolution upto 1 year
65. CAVERNOUS SINUSES
Situation:- middle cranial fossa
- either side of body of sphenoid
Size:- Length= 2cm width=1cm
Caverns: no. of spaces divided by trabeculae
Extent:-Ant- upto medial end of superior orbital
fissure
-Post-upto apex of petrous temporal bone
Relations-
Structures
In lateral wall
Of sinus
Passing through
centre of sinus
Outside
Sinus
68. CAVERNOUS SINUS(CONTINUE)
Factors promoting expulsion of blood from sinus: -
Expansile pulsations of internal
carotid artery
- Gravity
- Position of head
Clinical anatomy:
1. Thrombosis of cavernous sinus
-D/t sepsis in danger area of face,nasal
cavities and PNS
69. CAVERNOUS SINUS (CONTINUE)
-Symptoms
Nervous:
- Severe pain in eye and
forehead
- Paralysis of muscles
supplied by C.N. 3rd,4th
6th
Venous :
- Oedema of
eyelids,cornea and root
of nose
- Exopthalmos
2. Pulsating exopthalmos
-Occurs when cavernous sinus communicates with
internal carotid artery
-Eyeball protrudes and pulsates with each heart beat
70. SUPERIOR SAGGITAL SINUS
Location-convex attached border of falx cerebri
Course-
Begins ant. at crista galli
Runs upwards and
backwards
Ends near internal occipital
protuberance at confluence
of sinuses
Usually becomes
continuous with right
transverse sinus
71. SUPERIOR SAGGITAL SINUS
Tributaries
Clinical anatomy
Thrombosis of superior saggital sinus
-d/t spread of infection from nose,scalp and
diploe
- c/f: 1. Rise in ICP 2.Delirium and convulsion
3. Paraplegia of UMN type
72. OTHER SINUSES
SINUSES LOCATION COURSE/FATE
1. INFERIOR
SAGGITAL
SINUS
Post. 2/3rd of lower free margin of
falx cerebri
Joins with great cerebral vein
forms Straight sinus
2. STRAIGHT
SINUS
Within junction of falx cerebri
and tentorium cerebelli
Continues as transverse sinus
usually of left
3.
TRANSVERSE
SINUS (rt larger
than lt)
Post. Part of attached margin of
tentorium cerebelli
Rt. TS - Continuation of
superior saggital sinus
Lt. TS - Continuation of
straight sinus
Extends from internal occipital
protruberence to base of Mastoid
process - Bends downwards -
Becomes Sigmoid sinus
73. OTHER SINUSES
SINUSES LOCATION COURSE/FATE
5. OCCIPITAL SINUS Attached margin of falx
cerebelli
Ends in confluence of sinuses
6. SPHENO-
PARIETAL SINUS
Post. Free margin of lesser
wing of Sphenoid
Drains into ant. Part of Cavernous
sinus
7. SUPERIOR
PETROSAL SINUS
Ant part of attached margin
of tentorium cerebelli
,along upper border of
petrous temporal
Drains Cavernous sinus into
Transverse sinus
8. BASILAR PLEXUS
OF VEINS
Clivus of skull Connects two Inf. Petrosal sinuses
