. Anatomy, descriptive and applied. Anatomy. 902 THE NERVE SYSTEM External rectus. The origin of each nerve is not Hmited to the nuclei of its side; a part is decus- sated and the decussated origin is related to the innervation of the Internal rectus. By means of association neu- juteniai rones in the medial longitu- dinal fasciculus the oculo- motor and abducens nuclei of one side are brought into relation, affording an organic basis for the synergism exist- ing between the Internal and External recti muscles in the conjugated lateral eye move- ments. The paradox of the facial nerve supplying
. Anatomy, descriptive and applied. Anatomy. 902 THE NERVE SYSTEM External rectus. The origin of each nerve is not Hmited to the nuclei of its side; a part is decus- sated and the decussated origin is related to the innervation of the Internal rectus. By means of association neu- juteniai rones in the medial longitu- dinal fasciculus the oculo- motor and abducens nuclei of one side are brought into relation, affording an organic basis for the synergism exist- ing between the Internal and External recti muscles in the conjugated lateral eye move- ments. The paradox of the facial nerve supplying muscles un- der the reflex dominion of the retina (Orbicularis oculi) instead of the oculomotor may be explained by the assumed existence of fibres emerging from the oculomotor nucleus, entering the medial longitudinal fasciculus and joining the root of the facial. Parts Derived from the Fore-brain. The fore-brain or prosencephalon includes those portions of the brain which are derived from the cephalic one of the three primary brain vesicles. It includes, according to prevailing schemas, a thalamic portion (the thalamencephalon or diencephalon) and the telencephalon. The two'divisions constitute a structural continuity and exhibit a mutual dependency so close that the arbitrary distinction now in vogue tends to mislead. The relations of "diencephalon" and "telen- cephalon" are further complicated by the intimate fusion of the sides of the former (thalami) with the floors of the latter; this caudatothalamic fusion, in the adult brain, gives rise to some difficulty in distinguishing the two segments. The internal capsule which intervenes between thalamus and lenticular nucleus also in- tervenes between lenticular nucleus and caudate nucleus, both telencephalic parts. External Morphology.—The diencephalon or thalamencephalon comprises the thalami, the pineal body or epiphysis and habenulse, the external geniculate bodies, and the pars mamillaris hypothalami
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectanatomy, bookyear1913
