The temporal line extends into the external sagittal crest. Lacrimal glands are also present near the orbit. The nasal and lacrimal bones border the frontal squama section and form the zygomatic process laterally and part of the orbit dorsally. The frontal bone is a paired structure joined by the interfrontal suture between the cranium and the face and enclosing the frontal sinuses. The musculotubal canal contains tensors of the soft palate. The tympanic membrane separates tympanic cavity from external acoustic meatus and encloses the auditory ossicle dorsally. The tympanic part is the ventral section of the temporal bone containing the tympanic bulla. The styloid process attaches the hyoid apparatus and a stylomastoid foramen is also present. Ventrally this structure forms the mastoid process. Occipital process and retrotympanic processes surround the external acoustic meatus whilst the petrosal part encloses the inner ear internally via the internal acoustic meatus. An articular tubercle and mandibular fossa are present. The squamous element joins the temporal process of the zygomatic bone to form the zygomatic arch and forms the articulating surface of the temporomandibular joint. It articulates with the frontal, parietal and sphenoid bones. The temporal bone is composed of squamous, petrosal and tympanic parts and forms the lateral wall of the cranial cavity. The hypoglossal canal is also within this structure. The paracondylar process provide muscle attachment sites for muscles of the head. Occipital condyles are present which articulate with the atlas to form the atlanto-occipital joint. The lateral parts (partes laterales) form the borders of foramen magnum. There are also external occipital protuberances present which provide muscle attachment sites for the nuchal ligament. The nuchal crest is often used as a landmark for collection of cerebrospinal fluid (CSF). A nuchal crest is present and is easily palpable. The squamous part (pars squamosa) is dorsal to lateral parts and occipital condyles. It has muscular tubercules on ventral surface where the flexors of the head and neck attach and a caudocranial fossa encloses the pons and medulla oblongata. The pars basilaris element is the caudal base of the cranium, although rostral to foramen magnum and joined by a cartilagenous suture to basisphenoid bone. The occipital bone forms the nuchal wall and the foramen magnum. The skull has various functions including protection of brain, support of the facial muscles by providing origin and insertion sites, development of foramen to provide entry and exit places for the vasculature and nervous system and a defense function.īones of the Skull Occipital Bone ( os occipitale) Cartilage or fibrous tissue separates the bones of the skull in the young animal and once growth has ceased, the sutures begin to ossify. The skull is made of many small bones, most of which are paired. Movement of the external appendages, mastication and facial expressions all rely on the movement of the facial muscles. The various facial muscles attach onto the skull in different places depending on their function. It is derived only from the neural crest and undergoes endochondral and intramembranous ossification. The viscerocranium is the pharyngeal skeleton. It undergoes intramembranous ossification. The dermatocranium lies dorsal to the brain and develops from the neural crest and mesoderm. The neurocranium develops from the neural crest and mesoderm and undergoes endochondral ossification. In some animals the skull is also used for defensive actions, for example in horned ungulates such as red deer stags. The skull protects the brain and head against injury and supports the structures of the face. The skull also includes the hyoid apparatus, mandible, ossicles of the middle ear and the cartilage of the larynx, nose and ear. The skull is divided into three components - the neurocranium, the dermatocranium and the viscerocranium. The shape and size of the skull varies widely, not only between species but also with age, breed and sex of similar species. Deer Skull with Antlers, Nabrown, date unknown
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