FACE
2. ID subdivisions of the trigeminal nerve and discuss their course and
distributions. (N 18)
TG supplies cutaneous innervation to the face, and motor to muscles of
mastication.
Branches of TG as it leaves parotid:
To-----------Temporal
Zanzibar----Zygomatic
By-----------Buccal
Motor-------Marginal mandibular
Car----------Cervical
Subdivisions:
1. Opthalamic (V1): upper 1/3 of face and head
Skin over top of head
Forehead
Upper eyelid
Conjunctiva
Portion of nose
2. Maxillary (V2)
Skin over lower eyelid
Portion of nose
Upper part of cheek
Upper lip
“approximately corresponds to the area in relation to the upper
jaw”
3. Mandibular (V3)
Skin over the lower jaw
This is the largest of the three divisions
Comes from the posterior part of the ganglion
Carries a motor component for the muscles of mastication
(masseter, temporalis, medial and lateral pterygoids)
3. Discuss Bells’ Palsy and trigeminal neuralgia.
Trigeminal neuralgia: (M 862, SN)
Sensory disorder of trigeminal nerve.
Characterized by sudden attacks of lightening like excruciating pain,
called paroxysmal pain.
Pain is often initiated by touching a trigger zone of the skin.
Cause may be due to an anomalous artery that compresses the nerve.
Sectioning of CN V may be necessary.
Also called tic douloureaux.
Bells, Palsey (M 857)
Injury to facial nerve or its branches, causing paralysis of facial muscles
on affected side.
Most commonly paralysis of facial nerve near the stylomastiod foramen.
Idiopathic (*cause unknown)
May occur after riding in a car or sleeping with the window open.
Results in:
Loss in tone of obicularis oculi: lower eye-lid everts, cornea is not
adequately hydrated, lubricated or flushed.
Loss in tone of buccinator and obicularis oris: Loss in ability to
whistle, blow into an instrument or chew. Food may accumulate in
between cheek and teeth.
Corner of mouth and eye may droop and fluids may dribble out.
4. Discuss the fiber type, course and distribution of the facial nerve.
Fiber type = Motor and sensory
Course and distribution:
-Emerges from stylomastoid foramen
-Immediately gives off branches to: Posterior belly of digastric
Stylohyoid muscle
-Gives of posterior auricular nerve which supplies:
Occipital belly of occipitofrontalis muscle
-Passes into the parotid gland and divides into 5 branches:
Temporal
Zygomaticus
Buccal
Mandibular
Cervical
(…To Zanzibar By Motor Car)
-These 5 branches supply:
ALL the muscles of facial expression
Sensory to the anterior 2/3s of the tongue
Parasympathetic to the sublingual, lacrimal and nasal
gland.
It has geniculate ganglion in the temporal bone
Runs in the facial nerve canal after separating from the acoustic nerve.
5. Explain the arterial supply and venous drainage of the face.
Internal carotid a. ophthalmic….terminating branches
Supraocular Supratrochlear
Angular artery
Lateral nasal
Facial artery
Superior labial
Inferior labial
External carotid artery
Cavernous sinus
Via superior ophthalmic vein
Facial vein
Via inferior ophthalmic
& deep facial vein
Pterygoid plexus
6. Discuss the lymphatic and venous spread of infection from the face into the
cranial cavity (M868, 878, N35)
The facial vein makes clinically important connections with the:
o Cavernous sinus - a venous sinus of the dura mater covering the brain -
through the ophthalmic vein
o Pterygoid plexus - a network of small vv within the infratemporal fossa -
through the inferior ophthalmic and deep facial vv.
Because of these connections, an infection of the face may spread to the
cavernous sinus and pterygoid venous plexus
Blood from the medial angle of the eye, nose and lips usually drains inferiorly
through the facial vein, especially when the person is erect
Because the facial vein has no valves, blood may pass through it in the opposite
direction; consequently, blood from the face may enter the cavernous sinus
In patients with thrombophlebitis of the facial v - inflammation of the facial v
with secondary clot formation - pieces of the infected clot may extend in to the
intracranial venous system, and produce thrombophlebitis of the cavernous
sinuses.
Infection of the facial vv spreading to the dural sinuses may result from
lacerations of the nose or be initiated by squeezing pimples on the side of the nose
and upper lip.
Therefore, the triangular area from the upper lip to the bridge of the nose is
considered the danger triangle of the face.
7. Describe the clinical tests evaluating the integrity of both the facial and
trigeminal nerves (SN)
Trigeminal nerve:
Clinical tests involve testing for the sensation of the face and motor integrity as
evidenced by the ability to chew and clenching of teeth
Signs of involvement:
o Pain
o Loss of sensation
o Paralysis of mm of mastication
o Deviation of jaw to affected side
o Impaired hearing
o Trigeminal neuralgia: syndrome with excruciating pain and paroxysmal
pain of short duration with trigger zone. ??????
Facial nerve:
Four muscles are important in evaluating the integrity of the facial nerve
Frontalis: raises eyebrows
Orbicularis oculi: closes eyelids
Orbicularis oris: enable smiling
Buccinator: ability to whistle