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===Frontal Bone (os frontale)===

'''Frontal Bone (os frontale)'''

The frontal bone is a paired structure joined by the '''interfrontal suture''' between the cranium and the face and enclosing the '''frontal sinuses'''. The nasal and lacrimal bones border the frontal squama section and form the zygomatic process laterally and part of the orbit dorsally. Lacrimal glands are also present near the orbit. The '''temporal line''' extends into the '''external sagittal crest'''. Ruminants also have a '''cornual process''' in [[Horn - Anatomy & Physiology|horned]] variants. The nasal section is the rostral part of the frontal bone and the orbital part is perforated by the '''ethmoidal foramen'''. Medially the '''dorsal oblique muscle''' of the eyeball attaches. The temporal part provides the muscle attachments for the '''temporalis muscle'''.

 

*Joined by the interfrontal suture

*Between the cranium and the face

*Encloses the frontal sinuses

*The nasal and lacrimal bones border the frontal squama section  

**Forms the zygomatic process laterally

**Forms the dorsal part of the orbit

**Lacrimal gland present

**Temporal line present which extends into the external sagittal crest

**Cornual processes in [[Horn - Anatomy & Physiology|horned]] ruminants

*The nasal section is the rostral part of the frontal bone

*Orbital part is perforated by the ethmoidal foramen

**Medially the dorsal oblique muscle of the eyeball attaches

*Temporal part provides the muscle attachments for the temporalis muscle

[[Image:Pareital Bone.jpg|thumb|right|150px|Parietal bone, occipital bone and external acoustic meatus (Horse) - Copyright nabrown RVC]]

[[Image:Pareital Bone.jpg|thumb|right|150px|Parietal bone, occipital bone and external acoustic meatus (Horse) - Copyright nabrown RVC]]

 

'''Parietal Bone (os parietale)'''

 

===Parietal Bone (os parietale)===

The parietal bone is a paired structure and forms the dorsolateral wall of the cranium with the cccipital bone caudally and the frontal bone rostrally. It is composed of a pareital plane, temporal plane and a nuchal plane (in the ox). Internally the grooves and ridges correspond with the gyri and sulci of the brain. There is also an '''interpareital bone''' between the occipital bone and the pareital bone which fuses with age.

*Forms the dorsolateral wall of the cranium

*Occipital bone caudally

*Frontal bone rostrally

===Ethmoid Bone (os ethmoidale)===

*Composed of a pareital plane, temporal plane and a nuchal plane (in the ox)

*Internally the grooves and ridges correspond with the gyri and sulci of the brain

*Interpareital bone between the occipital bone and the pareital bone

**Fuses with age

 

'''Ethmoid Bone (os ethmoidale)'''

[[Image:Nasal Cavities.jpg|thumb|right|150px|Nasal Cavities - Copyright David Bainbridge]]

[[Image:Nasal Cavities.jpg|thumb|right|150px|Nasal Cavities - Copyright David Bainbridge]]

 

The ethmoid bone forms part of the cranial and facial parts of the skull and is located deep in the orbit. External lamina consist of the roof plate, floor plate and paired orbital plates. The ethmoid bone is separated from the cranial cavity by the '''cribiform plate'''. Numerous small foramina exist where the '''olfactory nerve''' ([[Cranial Nerves - Anatomy & Physiology|CN I]]) passes through. The perpendicular plate splits the ethmoid into two halves and the ethmoid larbyrinth prodrudes from the ethmoid tubes. The tubes are composed of two rows of '''ethmoturbinates''' and air filled '''ethmoidal meatuses'''. Secondary ethmoturbinates may also be present. Ethmoturbinates are divided into '''endoturbinates''' and '''ectoturbinates'''. The first endoturbinate forms the dorsal nasal conchae and the second endoturbinate froms the middle nasal conchae. The endoturbinates form 3 nasal meatuses; the '''dorsal nasal meatus''', the '''middle nasal meatus''' and the '''ventral nasal meatus'''

*Forms part of the cranial and facial parts of the skull

*Located deep in the orbit

*External lamina consists of the roof plate, floor plate and paired orbital plates

===Nasal Bone (os nasale)===

*The ethmoid bone is separated from the cranial cavity by the cribiform plate

**Numerous small foramina where the olfactory nerve ([[Cranial Nerves - Anatomy & Physiology|CN I]]) passes through

*The perpendicular plate splits the ethmoid into two halves

*The ethmoid larbyrinth prodrudes from the ethmoid tubes

**Composed of two rows of ethmoturbinates and air filled ethmoidal meatuses

**Secondary ethmoturbinates may also be present

*Ethmoturbinates divided into endoturbinates and ectoturbinates

**The first endoturbinate forms the dorsal nasal conchae

**The second endoturbinate froms the middle nasal conchae

*The endoturbinates form 3 nasal meatuses

**Dorsal nasal meatus

**Middle nasal meatus

**Ventral nasal meatus

 

'''Nasal Bone (os nasale)'''

[[Image:Ethmoid Turbinates.jpg|thumb|right|150px|Ethmoid Turbinates (Dog) - Copyright nabrown RVC]]

[[Image:Ethmoid Turbinates.jpg|thumb|right|150px|Ethmoid Turbinates (Dog) - Copyright nabrown RVC]]