3- Oculomotor These three nerves are responsible for Controlling the extraocular muscles which Are responsible for eye movement. L6 SO4 / 3 4- Trochlear 6- Abducent. Recti act as elevator or depressor alone when the eye is abducted (turned temporally). Obliques act as elevator or depressor alone when the eye is adducted (turned nasally). L6 SO4 / 3 = Lateral rectus is controlled by the 6th , Superior Oblique is controlled by the 4th & the other eye muscles are controlled by the 3rd nerve.

Examination: Abducent nerve supply lateral rectus and cause abduction Trochlear nerve supply superior oblique and cause down ward movement when the eye is adducted. Oculomotor nerve supply A- All remaining extra ocular muscle. B- Sphincter pupillae muscle. C- Muscles of accommodation. D- Levator palpebrae superioris. Examination: Ask the patient to look at your finger while you are moving Your finger : inward, outward, upward, downward.

Abnormalities: 1- Infra nuclear lesions (LMNL) of these nerves: A- Abducent: inability to move the eye outward, diplopia on Looking at that direction (convergent squint). B- Trochlear: impaired downward movement, diplopia Below the horizontal line. C- Oculomotor: Ptosis The eye is displaced downward and outward. Further movement is only possible outward and little downward. Pupil is dilated and fixed. loss of accommodation to near and far vision. Squint= أحول , ptosis is incomplete closure of the eye. Diplopia = ازدواجية البصر

2- Supra nuclear lesion (UMNL): Note: Smooth muscle in the upper lid is also innervated by cervical sympathetic chain which elevate the upper lid. Paralysis or damage to these nerves leads to: Slight ptosis. The pupil is small. (this condition called Horner syndrome). Dryness of that side of face (no sweating). 2- Supra nuclear lesion (UMNL): Normally the movement of two eyes are symmetrical so that the visual axis meet at the point at which the eyes are directed. This is referred to as conjugated movement of the eyes. This is due to the functions of the brain stem that integrate the functions of occulomotor, Trochlear and abducent nerves. So UMNL (supra nuclear) lead to paralysis of conjugated movements of the eyes.

Examination of pupils: The examination should be always bilateral 1- size of pupils. 2- shape. 3- Mobility (reaction to light). 4- Reaction to accommodation. Reaction to light The pupillary reaction to light is a reflex in which afferent fibers travel via optic nerve and efferent fibers via oculomotor nerve. a- Direct light reflex: Examine each eye separately, close one eye then apply light on one eye and look to pupillary movement: the pupil constrict directly then dilated a little then few oscillation occur then settle down to small size. but when the light off: the pupil dilates suddenly.

b- consensual reaction: one eye is kept in shade while directly illuminate the other eye directly by a bright light. observe the eye in shade for constriction of pupil. Reaction to accommodation: The pupil become smaller on accomodation for near objects (miosis). Convergence, accomodation and miosis are closely related reflexes. Hold one finger close to the patients nose and ask him to look away at a distant object then ask him to look quickly at your finger now as the eyes convergence the pupil become smaller. Mydriasis= dilated pupil, miosis= constricted pupil.

5- Trigeminal nerve (sensory and motor) Motor functions: Masseter and temporalis muscle (jaw closure) Medial and lateral ptyregoids ( jaw opening) Sensory functions: Division 1 ophthalmic Division 2 maxillary Division 3 mandibular Areas of sensory supply: Skin of face, cornea, conjunctiva, mucosa of sinuses, Mucosa of cheek, teeth, gums, tympanic membrane and Anterior 2/3 of the tongue.

Examination of motor function: By clenching and palpate the temporal and masseter muscles which become prominent on each side. If there is paralysis in each side, the muscle of that side will be less Prominent, also opening of the mouth the jaw will deviate to the normal side due to inappropriate action of lateral Pterygoid muscle. Examination of sensory function: By touch, temperature, pricking… etc Note: keeping in mind each division. Corneal reflex: By alight swab of cotton touch the lateral border of cornea At its conjunctival side, the patient will blink the upper lid if the reflex is present. Always compare both sides.

7- Facial nerve Facial nerve examination: Functional branches: Somatic motor: supplies muscles of facial expression and stapedius. Visceral efferent parasympathetic: lacrimal gland, submandibular and sublinqual salivary glands. somatic afferent: transmits impulses from taste buds on anterior 2/3 of tongue. Facial nerve examination: 1- Ask the patient to shut his eyes as tightly as he can, the affected eye cannot be closed. 2- Ask the patient to wrinkle his forehead, in LMNL the brow loss its wrinkle in the affected side. 3- Ask the patient to do whistle, in facial nerve disease the patient cannot do this. 4- Ask him to smile or show his upper teeth, the mouth is drawn to healthy side.

8- Vestibulo – cochlear nerve: 5- Ask him to inflate his mouth with air and blow out his cheeks then tap with finger on each inflated side, the air escape from the mouth more easily on the weak side (side of facial nerve diseased). 6- Test the sense of taste on the anterior 2/3 of the tongue. 8- Vestibulo – cochlear nerve: A- Vestibular branch supply the labyrinth and semicircular canal and serves the equilibrium and balance. b- Cochlear branch supply the cochlea and serves the hearing.

9- Glosso pharyngeal nerve: A- sensory from the posterior third of the tongue, the mucous membrane of pharynx and palate. B- Motor fibers to middle pharyngeal sphinctor and stylopharyngeus muscle. Examination: A- Tickle the back of pharynx and note if reflex contraction occur (palatal reflex) or reflex (this is also test of vagus n.) B- Examine the sense of taste of posterior third of the tongue.

10- Vagus nerve: Motor: Supplies the soft palate (with exception of tenser palati), pharynx and larynx. motor and sensory for respiratory passage, heart, parasympathetic to the chest and most abdominal viscera. For direct examination of the soft palate ask the patient to open his mouth and introduce a tongue depressor and ask the patient to say (ah), if there is vagus nerve paralysis, the paralyzed side of the uvula will remain flat and immobile and deviate to the normal side.

Damage of the palatal branch cause regurgitation of food and fluid during eating also cause dysphagia and nasal speech. Damage of superior laryngeal branch cause relaxation of vocal cords and hoarseness of voice. The reccurent laryngeal branch supply sensation to larynx below the level of vocal cord and motor to all laryngeal muscles except cricothyriod muscle.

11- Accessory nerve: Purely motor which supply: a- Innervation of pharynx and larynx b- Innervation of Sternocledomastoid c- Innervation of the Trapezius. paralysis of trapezius muscle is obvious by asking the patient to shrug his shoulder, the paralyzed muscle does not contract and when the patient arms are extended there will be winging of the Scapula in that side.

12- Hypoglossal nerve: supply motor fibers to intrinsic and extrinsic muscles of the tongue and depressors of the hyoid bone. Examination: Ask the patient to protrude his tongue, normally it will move out without deviation, but when there is paralysis of one side of this nerve, it will deviate to the normal side. Note: The 9th , 10th , 11th and 12th cranial nerves arise in the medulla and upper cervical cord and move in the same coarse, for this reason they usually damaged together.