The exterior: what you can see
The forehead sits on the frontal bone, above the eyes; in the dog, the frontal bones form a small central depression and slope down toward the nose. The stop, the step between forehead and nose, is a show-ring term, defined by the Kennel Club glossary, not an anatomical one. The bridge of the nose covers the nasal bones; at the end, the nose leather, the bare skin with the comma-shaped nostrils. The cheek is the lateral wall of the mouth, firm over the masseter, soft in front; the lips are thin and mobile, with the upper lip larger and, in some breeds, pendulous (“flews”). The chin is far less marked than in humans. The eyelids include, in the corner toward the nose, the third eyelid, which humans do not have.
The vibrissae, the whiskers and the other thick hairs of the face, are organs of touch: in the dog six groups are confirmed, above the eyes, on the upper and lower lip, on the chin, on the cheeks and in the zygomatic region, plus microvibrissae on the lips; touching the ones above the eyes and the whiskers triggers a blink, and the dog pushes them forward when exploring (Döring 2025).
The nose
The nose leather is cold, wet and sensitive to radiant heat; the nostrils take separate air samples, and the vestibule splits the flow: part toward the olfactory recess, the rest toward the lungs. The full path, with the sectional drawing and the brain, is on the pages “Journey of a scent” and “The dog's brain”.
The bones of the face and skull
The face: the incisive bone holds the upper incisors, the nasal bones make the roof of the nose, the maxilla, the largest bone of the face, carries the upper canine, premolars and molars, and its infraorbital foramen lets out the nerve that gives sensation to the lip and nose; the zygomatic bone is the cheekbone. The skull: the frontal, with the frontal sinus inside it, the parietal, with the crest to which the temporalis attaches, the temporal, with the tympanic bulla and the jaw joint, and the occipital, with the “bump” at the nape and the condyles on which the atlas vertebra rests. Inside, the ethmoid with the cribriform plate separates the nose from the brain; between the jaws, the hyoid apparatus supports the tongue and the larynx. The palpable landmarks and the skull types are on the page “The dog's skull”.
The muscles of the face
All the superficial muscles of the head are innervated by the facial nerve. The levator nasolabialis runs down broadly from the forehead and the nasal bones to the upper lip and the wing of the nostril: it lifts the lip and pulls on the nostril; there are no “special” nasal muscles in the dog, according to Sisson. The buccinator, broad and very thin, is the foundation of the cheek and pulls the corner of the mouth back; the orbicularis oris, weak in the dog, closes the lips; the orbicularis oculi closes the eyelids. Chewing: the temporalis and the masseter close the mouth, the digastricus opens it. The auricular muscles turn each ear separately.
What is inside: tongue, glands, brain
The tongue, wide and thin in front, thick at the root, very mobile, attaches to the hyoid and the chin; on its underside lies the lyssa, a fibrous cord peculiar to carnivores. The parotid gland sits at the base of the ear and sends its saliva through a duct that crosses the cheek; the round mandibular gland can be felt below the angle of the jaw, and the mandibular lymph nodes, just under the skin, swell with infections of the face. In the cranial cavity: the hemispheres, with the olfactory bulb at the tip, the cerebellum and the brainstem at the back, the pituitary below, in its fossa.
What it means for mantrailing
The trailing dog's head is an instrument: the nose a finger's width from the ground, the lips and the nostril moved by the levator nasolabialis, the tongue out when it pants, that is, when it is not sniffing, the whiskers feeling the grass. When you put on the harness and the long line, leave the head free: everything that matters happens there.