FOCUSED REVIEW: AUTONOMIC INNERVATION OF THE EYE AND ORBIT

1. FOCUSED REVIEW: AUTONOMIC INNERVATION OF THE EYE AND ORBIT I. ORBIT - eyelid; lacrimal gland II. EYE - pupil; lens

2. AUTONOMIC = VISCERAL NERVOUS SYSTEM Autonomic Nervous system = Visceral nervous system - involuntary, unconscious part of nervous system; control smoothand cardiac muscle, glands and internal organs: two neuron pathway PARASYMP. EYE Postganglionic Neuron Preganglionic Neuron smooth muscle, gland CNS SYMP. GANGLION PARASYMPATHETICS - cranio-sacral - ganglia close to target organ SYMPATHETICS - thoraco-lumbar - many ganglia in sympathetic chain PARASYMP.

3. SYMPATHETICS IN THORAX, ABDOMEN: Thoraco-Lumbar T1-T12, L1(2) SYMPATHETICS TO HEAD: leave cord at T1, T2 - Preganglionic neuron in spinal cord at T1, T2 - leaves and ascends sympathetic chain - Preganglionic neuron in spinal cord, enters white communicating ramus and synapses in sympathetic ganglion - Postganglionic fiber leaves via grey communicating ramus to innervate target Clinical: Compression of sympathetic chain in neck can produce symptoms in head due to compression of ascending sympathetic pre-ganglionic fibers

4. SYMPATHETICS TO HEAD NERVE PLEXUS ON CAROTID ARTERIES SCG - SUPERIOR CERVICAL GANGLION Second neuron In Superior Cervical Ganglia Joins Plexus on Internal and External Carotid Arteries (mostly unnamed branches) Superior Cervical Ganglion is located at base of skull, posterior to Carotid sheath, below Jugular Foramen, lateral to Retropharyngeal space;

5. PARASYMPATHETICS - IN CRANIAL NERVES III VII IX X +palate

6. 1) EYELID - Levator Palpebrae Superioris lifts eyelid - consists of skeletal and smooth muscle; skeletal muscle - CN III; smooth muscle from sympathetics 2) LACRIMAL GLAND - innervated by parasympathetics from CN VII 3) in EYE - Pupil - Constrictor - Parasympathetics from CN III Dilator - Sympathetics Ciliary muscle - controls lens - Parasympathetics from CN III

7. MUSCLE OF EYELID: LEVATOR PALPEBRAE SUPERIORIS LEVATOR PALPEBRAE skeletal muscle III smooth muscle sympathetics TARSAL PLATE LEVATOR PALPEBRAE SUPERIORIS MUSCLE - ORIGIN FROM TENDINOUS RING - COMPOSED OF SKELETAL (CN III) & SMOOTH (SYMPATHETICS) MUSCLE PARTS DAMAGE INNERVATION PTOSIS = DROOPING EYELID

8. PTOSIS = DROOPING EYELID; CAN BE SIGN OF DAMAGE TO OCULOMOTOR NERVE (III) OR SYMPATHETICS SKELETAL MUSCLE PART SMOOTH MUSCLE PART SYMPATHETICS - HORNER'S SYNDROME - - Miosis - constricted pupil - Anhydrosis - lack of sweating OCULOMOTOR NERVE PALSY other symptoms: - Pupil is dilated - denervate pupillary constrictor (mydriasis) - Also affect Eye movements - Accomodation

9. AUTONOMIC PARASYMPATHETICS TO LACRIMAL GLAND LACRIMAL GLAND - LOCATED IN SUPEROLATERAL ORBIT - OPENS BY DUCTS (~12) THROUGH CONJUNCTIVA TO SUPERIOR FORNIX -TEARS CONSTANTLY PRODUCED SAC LACRIMAL PUNCTUM - TEARS DRAIN THROUGH LACRIMAL PUNCTA TO LACRIMAL SAC TO NASOLACRIMAL DUCT TO INFERIOR MEATUS OF NASAL CAVITY B. LAC. GLANDINNERVATED BY VII- COMPLEX PATHWAY

10. PARASYMPATHETIC PATHWAY OF VII TO LACRIMAL GLAND 1) leaves Facial canal and forms N. Of Pterygoid Canal; ends (synapses) in PterygoPalatine Ganglion 2) Post ganglionic fibers distributed (hitchhike) withBRANCHES OF V1 AND V2 LACRIMAL GLAND V1 LACRIMAL N. Greater Petrosal N. V2 ZYGOMATIC N. V2 PTERYGOPALATINE GANGLION VII Clinical - Damage to VII can affect tear production in lacrimal gland

11. AUTONOMICS TO SMOOTH MUSCLES OF EYE DILATOR PUPIL M.- RADIAL SMOOTH MUSCLE; SYMPA-THETICS IRIS - PIGMENTED, CONTRACTILE LAYER SURROUNDING PUPIL IRIS - PIGMENTED PUPIL CONSTRICTOR PUPIL M. - CIRCULAR SMOOTH MUSCLE; PARA-SYMPATHETICS III PUPIL

12. PARASYMPATHETIC MECHANISM OF ACCOMODATION SUSPENSORY LIGAMENTS OF LENS ACCOMODATION- THICKEN LENS FOR NEAR VISION; PARASYMPATHETIC CONTROL- III (CILIARY GANGLION) CILIARY BODY- ATTACHES SUSPENSORY LIGAMENTS OF LENS CONTAINS CILIARY MUSCLES CILIARY MUSCLES CILIARY MUSCLES- SMOOTH MUSCLES CONTRACT PRODUCE - RELAXATION OF LIGAMENTS - THICKENING LENS

13. CAVERNOUS SINUS OPHTHALMIC VEINS Cavernous sinuses - in middle cranial fossa; on side of the body of the sphenoid bone; receive blood from Sup. and Inf. Ophthalmic veins; drain to Sup. and Inf. Petrosal sinuses Pituitary stalk Sup. and Inf. Petrosal sinuses - on petrous part of temporal bone

14. SPREAD OF INFECTION FROM FACE TO BRAIN Anastomoses of Facial and Ophthalmic Vv. - Ophthalmic veins drain to cavernous sinus (venous sinus inside skull) OPHTHALMIC VEIN NOSE FACIAL VEIN PTERYGOID VENOUS PLEXUS CLINICAL: Prolonged infection on face (lateral to nose) produces 'Blurred vision' (Diplopia); Prolonged infections spread via veins (pressure low, no valves) through orbit via Ophthalmic Veins to Cavernous Sinus; - Infections lateral to nose particularly dangerous; also infections from teeth can spread through pterygoid venous plexus

15. CRANIAL NERVES AND CAROTID ARTERY PASS THROUGH WALL OF CAVERNOUS SINUS STRUCTURES PASSING THROUGH WALL OF CAVERNOUS SINUS - Int. Carotid A., Cranial N.'s III, IV, V1, V2, VI; SYMPTOM of Infection in Sinus – ‘BLURRED’ VISION; not affect CN II no direct effect on II INTERNAL CAROTID PITUITARY III IV CAV. SINUS V1,V2 VI

16. CAVERNOUS SINUS SYNDROME CAUSES 1) Aneurysm of the internal carotid artery in the cavernous sinus, 2) Infection or venous thrombus (blood clot) in cavernous sinus, or by 3) Pituitary tumor encroaching into sinus. NERVES EFFECTED III, IV, V1, V2, and VI and Sympathetic fibers to orbit (travel on Internal Carotid) SPREAD OF INFECTION TO CAVERNOUS SINUS

17. CAVERNOUS SINUS SYNDROME SYMPTOMS 1) III - Ocular palsy (impaired eye movement) - Damage III - Dilated pupil (paralyze constrictor) - No pupillary light reflex (paralyze pupillary constrictor) - No accommodation (paralyze ciliary muscle) - Ptosis (drooping eyelid, paralyze levator palpebrae superioris) 2) V1, V2 Facial pain (pressure on nerves) 3) Sympathetics on Internal Carotid Ptosis (drooping eyelid) Miosis (constricted pupil) SPREAD OF INFECTION TO CAVERNOUS SINUS

18. GOOD LUCK!