Skin innervation of the face

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Skin innervation of the face

• Skin of the face is supplied by branches of
  trigeminal nerve except the area over the angle
  of mandible parotid gland, which is supplied by
  great auricular nerve..
• Ophthalmic nerve supplies the region developed
  from the frontonasal process.
• The maxillary nerve supplies the region developed
  from the maxillary process of 1st pharyngeal
  arch.
• The mandibular nerve supplies the region
  developed from the mandibular process of 1st
  pharyngeal arch.
• Skin of face has numerous sweat sebaceous
  glands. It is connected to underlying bones by
  loose C.T, in which are embedded the muscles of
  facial expression.
• No deep fascia is present in the face.

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Ophthalmic Nerve

• It supplies skin of forehead,
  upper eyelid, conjunctiva, side of the nose, it
  has 5 branches
• 1-Lacrimal N. supplies skin conjunctiva of
  lateral part of upper eyelid.
• 2-Supraorbital N. winds at supraorbital notch,it
  supplies skin conjunctiva on the central part
  of upper eyelid skin of forehead.
• 3-Supratrochlear N. it lies medial to
  supraorbital N. it supplies skin conjunctiva on
  medial part of upper eyelid skin of forehead.
• 4-Infratrochlear N. leaves orbit to supply skin
  conjunctiva on the medial part of upper eyelid
  skin of adjoining part of the side of the nose.
• 5-External nasal N. leaves nose to supply skin
  on the side of the nose down as far as the tip.

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Maxillary Nerve

• It supplies the skin of posterior part of the
  side of nose, lower eyelid, cheek, upper lip,
  lateral side of the orbit. It has 3
  branches
• 1-Infraorbital N. is a direct continuation of
  maxillary N. it leveas orbit via infraorbital
  foramen. It gives numerous small branches to
  supply skin of lower eyelid cheek, side of
  nose, the upper lip.
• 2-Zygomaticofacial N. passes onto face via a
  small foramen on lateral side of zygomatic bone
  to supply skin over the cheek.
• 3-Zygomaticotemporal N. passes through a small
  foramen on the posterior part of zygomatic bone
  to supply skin of temple.

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Mandibular Nerve

• It supplies skin of lower lip, lower part of
  face, temporal region part of the auricle
  side of scalp. It has 3 branches
• 1-Mental N. emerges from the mental foramen of
  mandible to supply skin of lower lip chin.
• 2-Buccal N. enters the face from under cover of
  the masseter. It passes over the buccinator. It
  supplies skin m.m of cheek.
• 3-Auriculotemporal N. leaves upper border of
  parotid gland , between superficial temporal
  vessels auricle to supply skin of auricle,
  external auditory meatus, outer surface of
  tympanic membrane skin of scalp above auricle.

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Arterial Supply of the Face

• Facial artery arises from external carotid
  artery.
  -it reaches face by piercing deep fascia at
  the lower border of the mandible and then curving
  up to the face close to anteroior border of
  masseter, here its pulse can be easily felt.
  
  -it then passes upwards in a tortuous course
  over the mandible and buccinator towards the
  angle of mouth.
  -it then ascends along side of nose to
  the medial angle of eye, where it anastomoses
  with the terminal branches of the ophthalmic
  artery.
• Superficial temporal artery the smaller
  terminal branch of external carotid artery within
  the parotid gland.It ascends in front of auricle
  to supply the scalp.

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Arterial Supply of the Face

• Transverse facial artery a branch of
  superficial temporal artery of external carotid
  artery, within the parotid gland.It runs forward
  across the cheek just above parotid duct.
• Infraorbital artery it is the terminal part of
  maxillary artery (one of terminal branches of
  external carotisd artery), it enters face via
  infraorbital foramen.
• Mental artery branch of inferior alveolar from
  maxillary from ext.c.artery, ,it enters face via
  mental foramen of mandible.
• Zygomaticofacial zygomaticotemporal arteries,
  from superficial temporal artery.
• Lacrimal artery from ophthalmic artery, of
  internal carotid artery.
• Supraorbital Supratrochlear arteries branches
  of ophthalmic artery, of internal carotid artery
  , supply skin of forehead.

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Branches of Facial artery
1- Submental artery arises at the lower border
of the body of mandible to supply skin of chin
lowe lip. 2- Inferior labial artery
arises near angle of mouth to run medially in the
lower lip and anastomoses with its fellow of
opposite side. 3-
Superior labial artery runs medially in the
upper lip and gives branches to the septum ala
of nose. 4- Lateral nasal artery supplies skin
on the side dorsum of nose.
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Venous Drainage of Face

• Facial vein
  -is formed at the medial angle of eye by union
  of supraorbital supratrochlear veins.
  -it is connected to cavernous
  sinus through superior ophthalmic vein. This
  connection is of great clinical importance
  because it provides a pathway for spread of
  infection from face to cavernous sinus.
  -It
  descends behind the facial artery to the lower
  border of body of mandible.
  -It crosses with the facial artery
  superficial to submandibular gland.
  It is joined by anterior division of
  retromandibular vein to form common facial vein
  to end into the internal jugular vein.

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Tributaries of Facial vein

• It recevies tributaries that correspond to the
  branches of facial artery.
• It is joined to pterygoid venous plexus ( a
  venous network lying around pterygoid muscles) by
  deep facial vein and to the cavernous sinus by
  superior ophthalmic vein.
• Transverse facial vein joins superficial temporal
  vein within the parotid gland.

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Lymph Drainage of the Face

• Lymph from forehead anterior part of face
  drains into submandibular L.Ns., a few buccal
  lymph nodes may be present along course of these
  lymph vessels.
• Lateral part of face lateral parts of eyelids
  drin into parotid L.Ns.
• Lower lip chin are drained into submental
  L.Ns.

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Facial Nerve

• It emerges from stylomastoid foramen to enter the
  parotid gland , it supplies all muscles of facial
  expression. it does not supply the skin ,It runs
  within substance of parotid gland, it divides
  into 5 terminal branches
  1- Temporal branch emerges
  from upper border of gland to supply anterior
  superior auricular muscles, frontal belly of
  occipitofrontalis, orbicularis oculi and
  corrugator supercillii.
  2- Zygomatic branch emerges from anterior
  border of parotid gland to supply orbicularis
  oculi.

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Facial Nerve
3- Buccal branch emerges from anterior border
of parotid gland below parotid duct to supply
buccinator ms.of upper lip nostril.
4- Mandibular branch emerges from anterior
border of parotid gland to supply ms. of lower
lip. 5- Cervical branch
emerges from lower border of parotid gland , it
descends in the neck to supply platysma muscle
depressor anguli oris muscle.
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Skin Fascia of the Face

• Skin of face has numerous sweat sebaceous
  glands.
• It is connected to the underlying bones by loose
  connective tissue (superficial fascia), in which
  are embedded muscles of facial expression.
• No deep fascia in the face.

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Muscles of Face (muscles of facial
expression)

• They are called ms. Of expression because they
  pull skin of face to produce various expressions.
• They are arranged in groups around the eye, nose
  mouth.
• They have bony origin.
• They are inserted into skin of face (no deep
  fascia in face).
• They are supplied by branches of facial N.,
  Except levator P.S. by occulomotor N. (striated
  ms.) sympathetic N. (smooth ms.).

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Muscles of Face
A) Muscles of eyelids
1- levator palpebrae superioris (the dilator ms.
of eyelids, lying in the orbital
cavity). 2-Orbicularis oculi (the sphincter ms of
eyelids). 3-Corrugator supercilii (deep to
orbicularis oculi). 4-Occipitofrontalis (ms.
of scalp).
B) Muscles of Nose
1-Procerus. 2-Compressor dilator naris.
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Muscles of Face

• C) Muscles of Lips
• Sphincter muscle of the lips
• Orbicularis Oris.
• Dilator muscles of the lips
• 1-Levator labii superioris alaeque nasi.
  2-Levator labii
  superioris. 3-Depressor labii
  inferioris.
  4-Zygomaticus minor.
  5-Zygomaticus major.
  6-Levator anguli Oris (deep to zygomatic ms.).
  7-Depressor anguli
  Oris. 8-Risorius.
  9-Mentalis.
  
• D) Muscles of Cheek
• Buccinator

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Muscles of Face (muscles of facial
expression)

• 3 large muscles
  1- Buccinator m. (ms. of cheek).
  2- Orbicularis oculi
  m. 3- Orbicularis
  oris m.
• Many small muscles
  1- Dilator ms. of lips (separate lips)
  
  -Levator labii superioris alaeque nasi, levator
  labii superioris.
  -Zygomaticus minor major.
  -Levator anguli oris, risorius depressor anguli
  oris.
  -Depressor labii inferioris mentalis.
  origin bones
  fascia around oral aperature.
  Insertion into
  substance of lips.

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2- Corrugator supercilli -It
lies deep to orbicularis oculi. origin
superciliary arch (bone).
Insertion skin of eyebrow.
Action vertical wrinkles of forehead, as
in frowning.
3- Compressor naris dilator naris
origin
maxilla. Insertion the fibres are continuous
with those of opposite side in front of the
bridge of nose to form aponeurosis of bridge of
nose.
Action compesses widens nasal cartilages and
aperature.
4- Procerus
- It is continuous with the
medial part of occipito-frontalis ms.
Origin nasal bone.
Insertion medial part of
skin of eyebrow. Action wrinkles skin of nose.
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• Orbicularis oculi
  1- Orbital part
  Origin medial palpebral ligament
  adjoining bone.
  Insertion The fibres have no lateral
  attachment, it loops return to origin.
  Action closes
  eyelids by throwing skin around orbit into folds
  to protect eyeball.
  2- Palpebral part
  Origin medial
  palpebral ligament.
  Insertion lateral palpebral raphe
  skin of eyelids.
  Action closes palpebral
  fissure of eyelids gently (sleep) and dilates
  lacrimal sac.

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• Orbicularis oris
  Origin maxilla, mandible deep skin.
  
  Insertion encircles oral orifice to be inserted
  to the m.m lining the inner surface of lips.
  Action compresses the lips together to
  close the mouth (sphincter muscle of lips).

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Muscle of Cheek Buccinator Muscle

• Origin from outer surface of maxilla mandible
  opposite the molar teeth from pterygomandibular
  ligament.
• Insertion
  1-upper fibres into upper lip. 2-lower
  fibres into lower lip. 3-middle fibres
  decussate at the angle of mouth.
• N.supply buccal branch of facial N.
• Action 1-
  it compresses the cheeks lips against the teeth
  to prevent accumulation of food in vestibule of
  mouth.
  2- it is used in wistling, when cheeks
  are distended with air.

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Muscle of Cheek Buccinator Muscle

• It is covered on outside by buccopharyngeal
  fascia buccal pad of fat.
• Its deep surface is lined by buccal mucosa.
• It is pierced by
  1-parotid duct , opposite upper 2nd molar tooth.
  2-Buccal branch of
  mandibular nerve (sensory) to supply m.m of cheek
  on the inner surface of buccinator muscle.

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Facial muscle Paralysis

• The facial ms. Are innervated by facial N.
• Cause Damage to facial N. (by a tumor in
  internal acoustic meatus or parotid galnd) /or
  operation or infection in middle ear / or
  perineuritis, Bells palsy in facial nerve canal.
• Results Lower motor neuron lesion which
  involves distortion of face drooping of lower
  eyelid angle of mouth will sag on the affected
  side. /But Upper motor neuron lesion is due to
  lesion of pyramidal tract and here the upper face
  is normal because the neurons supplying this part
  receive corticobulbar fibres from both cerebral
  cortices.

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The Cranial Cavity

• Contents of cranial cavity 1-
  the brain.
  2-meninges of brain (dura, arachnoid pia
  mater) from outside inwards.
  3-blood vessels of brain
  meninges.
  4-parts of cranial nerves.
  5-Blood venous sinuses.
  6- Hypophysis cerebri (pituitary gland).

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Dura Mater of Brain

• It is a thick dense membrane which consists of 2
  layers (outer inner).
• The 2 layers are attached together except at
  blood venous sinuses.
• Outer endosteal layer
  -it covers inner surface of bones of skull.
  
  -it is firmily attached to sutures of skull and
  to foramen magnum, it does not extend through
  foramen magnum .
• Inner meningeal layer
  -it covers brain and continuous with dura mater
  of spinal cord through foramen magnum.
  
  -it sends tubular sheaths around cranial nerves
  as they pass through foramina in skull.
  
  -it sends 4 septa into cranial cavity to
  divide cavity into spaces, these septa stabilize
  the brain within the cavity during movement of
  head.

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Dural Septa 1- Falx Cerebri

• It is a sickle-shaped fold of dura that descends
  in the midline between 2 cerebral hemispheres.
• Attachment
  -its narrow anterior end is attached to
  internal frontal crest crista galli.
  
  -its wide posterior end is attached to upper
  surface of tentorium cerebelli. -venous
  sinuses in falx cerebri 1-
  superior sagittal sinus lies in its upper
  convex fixed border. 2-
  inferior sagittal sinus lies in its lower
  concave free margin. 3-
  straight sinus lies at line of attachment of
  posterior end of falax with tentorium cerebelli.

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2- Tentorium cerebelli

• It is a crescentic fold of dura that roofs
  posterior cranial fossa.
• It separates the occipital lobe of cerebrum above
  from cerebellum below.
• Its free border
  -is concave and forms a gap called,
  tentorial notch, for passage of midbrain
  it crosses above the attached border of
  tentorium to be fixed at the 2 anterior clinoid
  processes.
  -at the point of crossing of the
  free attached borders the trochlear
  oculomotor Ns. Pierce the tentorium to enter
  lateral wall of cavernus sinus.
  -at the apex of petrous
  temporal bone the inferior layer of tentorium
  is invaginated anteriorly beneath the sup.
  Petrosal sinus to form a recess called trigeminal
  cave which contains the trigeminal ganglion.

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2- Tentorium cerebelli

• Attached border
  -it is convex and directed peripherally.
  -its posterior part is attached to the
  lips of transverse sulcus.
  -its anterolateral part is
  attached to the lips of groove for superior
  petrosal sinus (at the upper border of petrous
  temporal bone).
  -Its anterior
  end crosses below the free border and is attached
  to the 2 posterior clinoid processes.
• In the median plane
  -the superior layer of tentorium cerebelli
  is attached to falx cerebri.
  -the inferior layer of tentorium
  cerebelli is attached to falx cerebelli.

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2- Tentorium cerebelli

• Venous sinuses in the tentorium cerebelli
  
  1-straight sinus at the line of attachment of
  posterior end of falx cerebri with tentorium
  cerebelli.
  2-transverse sinus in the posterior part of
  the attached border.
  3-superior petrosal sinus in the
  anterolateral part of attached border.

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3-Falx Cerebelli

• It is a small sickle-shaped fold of dura placed
  in median plane below tentorium cerebelli.
• Its free anterior border projects forwards
  between the 2 cerebellar hemispheres.
• Its posterior border is attached to the internal
  occipital crest.
• It contains the occipital sinus in its posterior
  fixed border.

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4-diaphragma sellae

• It is a small circular fold of dura.
• It forms the roof of sella turcica.
• It has a centeral opening for passage of the
  stalk of hypophysis cerebri
  (pituitary stalk).

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Dural Nerve Supply

• Trigeminal N.
• Vagus N.
• First 3 cervical nerves.
• Sympathetic fibres around the meningeal arteries.

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Dural Arterial Supply

• Internal carotid artery.
• Maxillary artery. Middle meningeal artery, it is
  the most important branch.
• Ascending pharyngeal artery.
• Occipital artery.
• Vertebral artery.

Meningeal Veins

• Middle meningeal vein follows the branches of
  middle meningeal artery and drains into the
  pterygoid venous plexus or sphenoparietal sinus.

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Middle meningeal artery

• It is a branch of 1st part of maxillary artery.
• It reaches middle cranial fossa through foramen
  spinosum to lie between the meningeal endosteal
  layers of dura.
• It passes forwards and laterally grooving the
  squamous part of temporal bone. Then it divides
  into 1-large anterior (frontal) branch.
  2-small posterior (parietal) branch.
• It divides into anterior posterior branches
  opposite a point 20mm above center of zygomatic
  arch.

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Extradural hemorrhage

• This is intracranial hemorrhage outside the dura
  mater.
• It results mostly from injury of middle
  meningeal artery, usually occuring in the region
  of the pterion (at anteroinferior part of the
  parietal bone) as a result of a blow over the
  side of the head.
• A collection of blood,
  (extradural hematoma) occurs between the dura and
  the skull bones, stripping off the periosteum of
  inner table of the bone.
• The intracranial pressure rises producing local
  pressure on the motor area of brain.
• Blood may pass out through the fracture to form a
  soft swelling under the temporalis ms

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Arachnoid mater

• It is a delicate, impermeable membrane covering
  the brain, lying between pia mater dura mater.
• It is separated from the dura by subdural space,
  and from the pia by subarachnoid space, which is
  filled with cerebro-spinal fluid.
• The arachnoid projects into the venous sinuses to
  form arachnoid villi, they are most numerous at
  superior sagittal sinus, aggregations of
  arachnoid villi are called arachnoid
  granulations, where C.S.F diffuses into
  bloodstream.
• Cerebral arteries veins cranial nerves lie in
  subarachnoid space.

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Cerebrospinal fluid

• It is produced by the choroid plexuses within
  lateral, 3rd 4th ventricles of brain.
• It passes via 3 foramina in roof of 4th ventricle
  to circulate in subarachnoid space, upward over
  surfaces of cerebral hemispheres and downward
  around spinal cord.
• The spinal subarachnoid space extends down as far
  as 2nd sacral vertebra.
• The fluid enters bloodstream by passing into
  arachnoid villi and diffuses into venous sinuses.

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Pia mater

• It is a thin vascular membrane that closely
  covering the brain.
• It extends over the cranial nerves and fuses with
  their epineurium.
• The cerebral arteries enter the brain carrying a
  sheath of pia mater.

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Venous Sinuses

• They are blood channels between the endosteal
  meningeal layers of dura mater.
• The walls of sinuses are lined by endothelium.
• They receive tributaries from the brain, the
  diploe of skull, the orbit, the internal ear.
• They differ from the veins in having no valves,
  or muscles in their walls. So they do not
  contract when they are ruptured and bleeding is
  controlled only by pressure.
• Single sinuses are
  1-superior sagittal, 2-inferior sagittal,
  3-straight sinus 4-intercavernus sinus.
  5-Occipital sinus.

• Paired sinuses are
  1-transverse sinuses.
  2-sigmoid sinuses.
  3-cavernus sinuses.
  4-superior inferior
  petrosal sinuses.
  
  5-sphenoparietal sinuses.

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Superior Sagittal Sinus

• It lies in the upper fixed border of falx
  cerebri.
• It begins in front at frontal crest foramen
  cecum, where it receives vein from nasal
  cavity, then runs backward grooving vault of
  skull.
• At the internal occipital protuberance, it is
  dilated to form the confluence of the sinuses,
  here it deviates to one side (usually the right)
  to become the right transverse sinus.
• It is connected to the opposite transverse sinus
  and it receives the occipital sinus.

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Tributaries and communications of the Superior
Sagittal Sinus

• The sinus communicates with 2-3 venous lacunae on
  each side.
• Numerous arachnoid villi granulations project
  into the lacunae, which also receive the diploic
  meningeal veins.
• It receives also the cerebral veins.
• It communicates with veins of scalp by emissary
  veins passing through the parietal foramina.

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Inferior Sagittal Sinus

• It lies in the free lower border of falx cerebri.
• It runs backward to join great cerebral vein at
  free border of tentorium cerebelli to form
  straight sinus.

• Straight Sinus
• It lies at the junction of falx cerebri with
  tentorium cerebelli.
• It is formed by union of inferior sagittal sinus
  great cerebral vein.
• It ends by turning to left to form the left
  transverse sinus.

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Transverse Sinuses

• Are paired sinuses, begin at the internal
  occipital protuberance.
• Right sinus is usually continuous with the
  superior sagittal sinus, and left sinus is
  continuous with the straight sinus.
• Each sinus occupies the attached margin of
  tentorium cerebelli, grooving the occipital bone.
• They receive the superior petrosal sinuses,
  cerebral cerebellar veins, diploic veins.
• They end by turning downward as sigmoid sinuses.

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Sigmoid Sinuses

• Are direct continuation of transverse sinuses.
• Each sinus turns downward and medially and
  grooves the mastoid part of temporal bone, here
  it lies behind mastoid antrum.
• Finally, it passes through jugular foramen to
  join the internal jugular vein.

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Occipital sinus

• It is a small sinus occupying the attached border
  of falax cerebelli.
• It begins near foramen magnum, where it
  communicates with vertebral veins and drains into
  the confluence of the sinuses.
• It connects the beginning of transverse sinus
  with the end of sigmoid sinus.
• May be single or paired.

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Cavernus sinuses

• Are lie in middle cranial fossa on each side of
  body of sphenoid bone ( hypophyseal
  fossa).
• Each sinus extends from superior orbital fissure
  anteriorly, to apex of petrous temporal bone
  posteriorly.
• Inside the sinus
  1- internal carotid artery surrounded by
  sympathetic plexus.
  2- abducent nerve.
• In the lateral wall of cavernus sinus
  
  1-oculomotor nerve.
  2-trochlear nerve.
  3-ophthalmic nerve of trigeminal N.
  4-maxillary nerve of
  trigeminal N.

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Cavernus sinuses

• Tributaries
  1-superior inferior ophthalmic veins.
  2-cerebral veins.
  3- sphenoparietal sinus, along
  posterior margin of lesser wing of sphenoid.
  4-central vein of retina.
• Each sinus drains posteriorly into superior
  inferior petrosal sinuses and inferiorly
  into pterygoid venous plexus.
• The 2 sinuses communicate with each other by
  anterior posterior intercavernous sinuses,
  which run in diaphragma sellae.
• Each sinus has important communication with
  facial vein through superior ophthalmic vein.

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Superior inferior Petrosal sinuses

• Are small sinuses lying on the superior
  inferior borders of petrous part of temporal
  bone.
• The superior sinus drains the cavernus sinus into
  transverse sinus.
• The inferior sinus drains the cavernus sinus into
  internal jugular vein.

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Hypophysis Cerebri
(Pituitary gland)

• It is the master endocrine gland, which attached
  to brain by the infundibulum.
• Site sella turcica of sphenoid bone
  (hypophyseal fossa).
• It has 2 lobes, anterior lobe or adenohhypophysis
  and posterior lobe or neuro-hypophysis.
• Superiorly diaphragma sellae, which has a
  central aperature to allow passage of
  infundibulum.
• Inferiorly body of sphenoid sphenoid air
  sinuses.
• Laterally cavernus sinus.
• Posteriorly dorsum sellae, basilar artery,
  pons.
• Blood supply superior inferior hypophyseal
  branches of internal carotid artery / veins
  drains into intercavernous sinuses.

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Diploic Veins

• They are thin- walled, valveless veins lying in
  the diploe of skull (between the inner outer
  tables of the bones of skull).
• They communicate with the meningeal veins
  dural venous sinuses.
• They include frontal, temporal occipital
  diploic veins.

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Emissary Veins

• They are small valveless veins, pass via foramina
  in the skull and connect the dural venous sinuses
  with veins outside the skull.
• Function they help to equalize the pressure in
  veins outside the skull and in the dural venous
  sinuses.
• Their danger infection outside the skull may
  spread along the emissary veins to reach the
  dural venous sinuses and produce septic thrombi.

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Intracranial part of Internal Carotid Artery

• It enters the cranial cavity through the carotid
  canal in petrous part of temporal bone.
• It passes into foramen lacerum to enter the
  cavernus sinus.
• It lies with the abducent nerve on the floor of
  cavernus sinus.
• It pierces the roof of cavernus sinus to lie on
  the medial side of anterior clinoid process and
  divide into anterior middle cerebral arteries.
• Branches
  1-superior inferior hypophyseal arteries to
  pituitary gland. 2-
  meningeal branches.

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