A Guide for the Dissection of the Dogfish (Squalus Acanthias) — John Shaqi
A Guide for the Dissection of the Dogfish (Squalus Acanthias)Griffin, Lawrence Edmonds
Science
A Guide for the Dissection of the Dogfish (Squalus Acanthias)
Griffin, Lawrence Edmonds
Dogfish; Fishes -- Anatomy
The _superficial ophthalmic_ trunks of the two unite in a single nerve
which passes along the inner wall of the orbit above the muscles of the
eye to a foramen in the antero-medial angle of the orbit, through which
it passes to the dorsal surface of the snout. The superficial ophthalmic
nerve of Squalus is composed almost entirely of fibres of the facial
nerve. The superficial ophthalmic trunk of the trigeminal gives rise to
several small nerves leaving the common trunk near its origin and
passing to the skin above the eye. The superficial ophthalmic trunk of
the facial, nearly the whole of the common nerve, branches profusely to
supply the sensory organs of the dorsal and lateral surfaces of the
snout.
The superficial ophthalmic of Eugaleus rises from the dorsal part of the
trigemino-facial root and leaves the cranium by a separate foramen above
and anterior to the roots of the recti muscles.
Directly under the origin of the superficial ophthalmic will be found a
comparatively slender nerve, which passes between the superior and
posterior rectus muscles, and forward along the medial surface of the
eyeball; it penetrates the anterior wall of the orbit by a separate
foramen, and emerges under the superficial ophthalmic. It is distributed
to the skin of the dorsal and lateral surfaces of the snout. This is the
_deep ophthalmic_ (_ophthalmicus profundus_) of the trigeminal nerve. A
slender branch (_posterior ciliary nerve_) passes from the deep
ophthalmic near its origin to the posterior surface of the eyeball.
Farther forward the same trunk gives off an _anterior ciliary nerve_ to
the anterior part of the eyeball.
A large nerve which crosses the floor of the orbit, beneath the eyeball,
consists of the _maxillary_ trunk of the trigeminal and the _buccal_
trunk of the facial nerve. These remain associated, even into the small
branches. Near the anterior margin of the orbit the maxillary-buccal
trunk divides into three parts; the smallest and outer one passes to the
surface lateral and anterior to the eye. The other two dip downward and
pass in front of the jaw to the ventral surface of the snout. Reflect
the skin of the ventral surface of the snout, and by dissection expose
these nerves as they emerge from the orbit. The larger branch runs
forward close to the median line of the snout, giving off numerous
twigs; the other, which appears to be a pure trigeminal branch, is
distributed near the angle of the mouth. The fibres of the maxillary
trunk supply the skin, while those of the buccal go to the canal organs
and ampullae of Lorenzini.
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