The =external ear= is inclined outward. The middle part is much wider
and less curved than in the horse. The apex is also wide and does not
curve forward. The lower part of the anterior border is bent backward
and bears long hairs. The posterior border is thin and is regularly
convex, except below, where it is indented. The opening is wide and the
concave surface presents four ridges; the convex surface presents
corresponding depressions. The styloid process of the conchal cartilage
is short and blunt. The edges of the annular cartilage are in contact at
the inner side and the upper border is notched externally. The scutiform
cartilage is a very irregular quadrilateral plate; it is situated on the
lateral aspect of the cranium with its concave surface in contact with
the fat and temporalis muscle. The osseous external auditory meatus is
directed practically straight inward; it is about twice as long as that
of the horse, and tapers very gradually from without inward. The chief
special characters of the =auricular muscles= are as follows: (1) The
scutularis blends with the frontalis muscle. The interscutularis arises
from the base of the processus cornu (or the corresponding area in
polled cattle) and from the frontal crest. (2) The cervico-scutularis
arises from the posterior surface of the cranium below the frontal
eminence, and receives slips from the parieto-auricularis and
cervico-auricularis superficialis. (3) The zygomatico-auricularis and
scutulo-auricularis superficialis inferior are fused. (4) The
scutulo-auricularis superficialis superior is distinct from the
interscutularis; it arises from the superficial face of the scutiform
cartilage. (5) The cervico-auricularis superficialis arises from the
ligamentum nuchæ and ends on the convex surface of the conchal
cartilage. (6) The parieto-auricularis arises from the nuchal surface of
the frontal bone, the adjacent part of the parietal bone, and the
ligamentum nuchæ; it is inserted below the preceding muscle. (7) The
scutulo-auricularis superficialis accessorius arises from the
superficial face of the scutiform cartilage and is inserted by a round
tendon into the anterior part of the convex surface of the conchal
cartilage. (8) The cervico-auricularis profundus minor consists of two
fasciculi; the inner, narrow part is deep red in color, and arises from
the fascia of the cervical muscles external to the occipital attachment
of the ligamentum nuchæ; the outer, wider part is pale, and arises
beneath the cervico-auricularis superficialis, indirectly from the
scutiform cartilage. The two unite and are inserted into the lower
aspect of the base of the conchal cartilage. (9) The scutulo-auricularis
profundus minor arises from the temporal crest above the external
auditory meatus and is inserted into the anterior part of the deep face
of the scutiform cartilage.
The =cavum tympani= is small; it communicates ventrally with the
air-cells of the bulla ossea. The tympanic membrane is nearly circular
and is not so oblique as in the horse. The auditory ossicles are smaller
than those of the horse; the malleus is more curved, the body of the
incus is longer, and there is a small prominence on the front of the
head of the stapes for the attachment of the stapedius muscle.
The =Eustachian tube= is small and is only about two inches long. The
pharyngeal opening is small and is situated on the side of the fornix of
the pharynx close to the base of the cranium. There is no flap-like
expansion of the cartilage, but the inner border of the orifice is
formed by a fold of mucous membrane.
The =internal ear= has essentially the same arrangement as in the horse.