For those interested in learning more about the structure of the horse skull, a labeled horse skull diagram is a helpful tool. The horse skull is a 2-part skull (separate cranium & jaw) with long, broad nasals. The front of the mouth has large, squared incisors designed for cropping grass and in the back of the mouth are six large, rectangular molars on each side. The area between the molars is known as the bar and in it sits a canine tooth (not present in all horses). The teeth are numbered according to Triadan numbering system, where 1 is an upper right premolar, 2 is a lower left premolar, 3 is a middle premolar, 4 is a bottom premolar, and 5 is a molar. In younger horses, canines are vestigial and do not erupt through the gums.
Like all mammals, the horse has a braincase, cranial nerves, occipital bone, nasal bones, maxillary sinuses, palatine foramen, pharyngeal foramen, and vomer (Fig. 14B-3). However, due to intraspecific allometry and the horse’s grazing behavior, the equine skull is much longer than that of other mammals. This is a result of the long neck and crest that extends from the base of the skull to the withers.
The occipital bone is the large bone at the back of the head that forms a dome and houses the cerebellum. This bone is much longer in mares and can become fractured as a result of horse’s rearing behavior.
In a live horse, the infraorbital foramen is located in the area between the nasoincisive notch and the facial tuberosity. It is covered by the levator labii superioris muscle and needs to be pushed aside in order to locate the foramen.
The equine skull has two sets of sinuses, one that drains into the palatine foramen and one that runs up to the frontal sinus (Fig. 14B-4). The frontal sinus in a live horse opens into the maxillary sinus ventrally via a dorsal conchal sinus rostrally.