Skull and Facial Muscles - Anatomy & Physiology
Introduction
The skull is divided into three components- the neurocranium, the dermatocranium and the viscerocranium. The skull also includes the hyoid apparatus, mandible, ossicles of the middle ear and the cartilage of the larynx, nose and ear. The skull protects the brain and head against injury and supports the structures of the face. In some animals the skull is also used for defensive actions, for example in horned ungulates such as red deer stags.
The neurocranium develops from the neural crest and mesoderm and undergoes endochondral ossification. It lies ventral to the brain.
The dermatocranium lies dorsal to the brain and develops from the neural crest and mesoderm. It undergoes intramembranous ossification.
The viscerocranium is the pharyngeal skeleton. It is derived only from the neural crest and undergoes endochondral and intramembranous ossification.
Structure
- The skull is made of many smaller bones
- Most of the skull bones are paired
- Cartilage or fibrous tissue separates the bones of the skull in the young animal
- Once growth has ceased, the sutures begin to ossify
Function
- Protection of brain
- Support facial muscles by providing origin and insertion sites
- Foramen provide entry and exit places for the vasculature and nervous system
- Defense
Vasculature
Innervation
Lymphatics
Histology
Species Differences
Canine
- Dogs have different skull lengths depending on breed
- Mesocephalic dogs have average conformation
- Dolichocephalic dogs have longer skull lengths
- Brachycephalic dogs have shorter skull lengths