Neurology

department

TSMU

DONE BY :

MUSTAFA KHALIL IBRAHIm

4th year, 2nd sem, 1st group

CONTENTS

1. Introduction

2. Nuclei of origin

3. Course & Relations

4. Branches of facial nerve

5. Ganglia associated with facial nerve

6. Testing of facial nerve

7. Identification of facial nerve

8. Nerve injury

• The Facial nerve is the 7th of twelve paired cranial nerves. • It is a mixed nerve with motor and sensory roots. • It also supplies pre-ganglionic parasympathetic fibres to several

head and neck ganglia

Introduction

Nuclei of Origin

1. Motor nucleus

2. Superior salivatory nucleus

3. Nucleus of tractus solitaries This facial nuclei in pons is divided into :

1- Lower parts which innervate the upper half of

The face & it has double cortical innervation.

2- upper parts which innervate the lower half of

The face & it has single cortical innervation.

The facial nerve is formed mainly of two parts:

• 1- Facial nerve proper (motor): arising from facial motor nucleus in

pons.

• 2- Nervus intermedius: it is the sensory root of facial lies position between

the facial proper and vestibulcochlear nerve in the pontocerebellar angle.

Carrying para-sympathetic fibers (from superior salivary nucleus) and taste fibers

( to the solitary nucleus).

Course & Relations

• I- Intracranial (intrapetrosal) course

• II- Extracranial course

Branches

1. Greater superficial petrosal – arises from the geniculate ganglion.

2. Branches within the facial canal:

• i) nerve to stapedius

• ii) Chorda tympani

3. After exit from stylomastoid foramen:

• i) Posterior auricular

• ii) Nerve to posterior belly of digastric

• iii) Nerve to stylohyoid.

4. On the face - Five major branches:

• i) Temporal

• ii) Zygomatic

• iii) Buccal

• iv) Marginal mandibular

• v) Cervical

Ganglia associated with facial nerve

• Geniculate ganglion • Submandibular ganglion

• Pterygopalatine ganglion

Geniculate ganglion

• The geniculate ganglion (from Latin genu, for "knee") is an L-shaped collection of fibers and sensory neurons of the facial nerve located in the facial canal of the head.

• It receives fibers from the motor, sensory, and parasympathetic components of the facial nerve

Submandibular ganglion

• The submandibular ganglion is small and fusiform in shape. It is situated above

the deep portion of the submandibular gland, on the hyoglossus muscle, near the

posterior border of the mylohyoid muscle

Pterygopalatine ganglion

• The pterygopalatine ganglion (meckel's ganglion, nasal ganglion or

sphenopalatine ganglion) is a parasympathetic ganglion found in the

pterygopalatine fossa.

• It's largely innervated by the greater petrosal nerve (a branch of the facial

nerve); and its axons project to the lacrimal glands and nasal mucosa

Facial Nerve blood supply

• The facial nerve gets it’s blood supply from 5 vessels:

Anterior inferior cerebellar artery – at the cerebellopontine angle

Labyrinthine artery (branch of anterior inferior cerebellar artery) – within

internal acoustic meatus

Superficial petrosal artery (branch of middle meningeal artery) – geniculate

ganglion and nearby parts

Stylomastoid artery

(branch of posterior auricular artery) – mastoid segment

Posterior auricular artery supplies the facial nerve at & distal to stylomastoid

foramen

• Venous drainage parallels the arterial blood supply

Testing of Facial Nerve Branches

• Temporal branches -patient is asked to frown and wrinkle his or her forehead.

• Zygomatic branches -the patient is asked to close their eyes tightly

• Buccal branches -puff up cheeks (buccinator) smile and show teeth

(orbicularis oris) tap with finger over each cheek to detect ease of air expulsion on the affected side

Temporal branch

• It exits the parotid gland anterior to superficial temporal artery

During an open approach to the TMJ, violation of this branch is possible

Zygomatic Branch

• Its course is antero superior crossing the zygomatic bone

Inadvertent damage may occur to this nerve during open reduction of zygomatic arch or with the use of zygomatic hook during closed approaches

Buccal Branch:

• It runs almost horizontally and will often divide into separate branch above

and below parotid duct as it runs anteriorly

Injury is possible in association with soft tissue trauma to the cheek region

Marginal mandibular branch

• It extends anteriorly and inferiorly within the substance of parotid gland, there

may be two or three branches of this nerve.

These branches run anteriorly parallel to inferior border of mandible and in

some cases the course of the nerve is above the inferior border.

In essentially all cases the nerve is located above the inferior border of

mandible beyond the facial artery. The marginal mandibular branch is an

important structure encountered at the inferior border of the mandible just

beneath the platysma muscle fibres during an open approach to the mandibular

angle and body area.

• For this reason, an initial incision made approximately 1 to 1.5cm below the inferior border which prevents direct exposure or trauma to the nerve

Cervical Branch:

• The cervical branch exits the parotid gland above its inferior pole and runs downwards underneath the platysma muscle

3 surgical maneuvers used to identify

nerve trunk

A. Blood free plane in front

of external acoustic meatus

B. Exposure of anterior border of SCM below insertion into mastoid

process

C. Peripheral identification

of terminal branch of facial nerve (marginal

mandibular branch)

Identification of Facial Nerve

Duus'_Topical_Diagnosis_in_Neurology

Neuroanatomy atlas

ginsberg_l_lecture_notes_neurology

Dan Kirshenbaum BUSM Class of 2011 - Gross Anatomy 2007

Dr.Hassan Elwan Neurology

Also Some internet photos

References