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Motor nerves (CN III: Oculomotor (exits through superior orbital fissure…
Motor nerves
CN III: Oculomotor
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parasympathetic: same orbital fissure, ciliary ganglion, short ciliary nerves (V1), sphincter pupillae, ciliary.
somatic motor: levator palpebrae, superior rectus, medial rectus, medial rectus, inferior oblique, inferior rectus
sympathetic: synapse at the superior cervical ganglion (re: Horner's syndrome). post ganglionic fibers into head and neck via carotid arteries... superior tarsal raises eyelid. Dilator pupillae dilates pupil.
CN III lesion proper vs. lesion of the sympathetic system (Horner's syndrome).
CN III lesion: ptosis, midraiasis, "down and out" eye (lateral deviation). You would see midriasis FIRST during compression. First fibers will be the outer parasympathetic fibers.
Sympathetic lesion: horner's syndrome. Ptosis more mild. Miosis, anhidrosis (unilateral).
CN XI: Accessory spinal
Innervates trapezius muscle, sternocleidomastoid.
enters through foramen magnum, exits through jugular foramen. comes from c1-c5 nerve roots. These foramen are both part of the occipital bone.
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Purely motor - more of spinal nerve than a cranial nerve. but need to know, cervical roots going up through foramen magnum, out through jugular foramen. Innervates SCM and then goes through posterior triangle to reach trapezius.
LESION: weakness in turning head away from lesioned side. Should drop and weakness of scapular elevation.
CN IV: Trochlear
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Innervates superior oblique muscle - depends on position of the eye. Eye that is abducted, then function of superior oblique is to "intort" the eye. If the eye is adducted, the superior oblique muscle causes depression of the eye.
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Complaint - reading book, going down stairs, double vision. Head tilt, chin tuck helps correct extorsion and hypertropia.
CN XII: Hypoglosseal
Innervates styloglossus, instrinsic muscles of the tongue, genioglossus, hyoglossus.
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CN VI: Abducens
Lateral rectus muscle of the eye. Lesions - medially deviated eye. Rotate head towards the side of the lesion. The other eye can freely abduct as it needs to.