Regarding motor innervation to ocular structures, which of the following associations is NOT correct?

e. Extra-ocular muscles are supplied by three main cranial nerves: the oculomotor nerve (III), trochlear nerve (IV) and abducens nerve (VI). The abducens nerve supplies motor innervation to the lateral rectus muscle, the trochlear nerve supplies motor innervation to the superior oblique muscle and medial rectus, inferior oblique, superior and inferior rectus are all motor innervated by the oculomotor (III) nerve. A useful way of remembering this information is the ‘chemical formula’ – LR6SO4AL3 (Lateral Rectus 6, Superior Oblique 4, ALl the rest 3).

The innervation to levator palpebrae superioris (the muscle responsible for eyelid opening) is dual, involving both the sympathetic nervous system and the third cranial nerve (oculomotor nerve). This dual supply is evidence by the degree of ptosis (drooping of the eyelid) seen in oculomotor palsy and in conditions affecting the sympathetic supply to the head and neck, e.g. Horner’s syndrome. Partial ptosis is seen in Horner’s syndrome due to sparing of the oculomotor innervation to levator palpebrae superioris, whilst complete ptosis occurs in oculomotor palsies due to loss of both oculomotor and sympathetic tone (as sympathetic fibres run along the course of the oculomotor nerve). Supply to the lacrimal glands is from the parasympathetic nervous system and is delivered via the greater petrosal nerve, the deep petrosal nerve, and zygomatic and lacrimal nerves.