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==== Occipital Bone (''os occipitale'')  ====

==== Occipital Bone (''os occipitale'')  ====

The occipital bone forms the '''nuchal wall''' and the '''foramen magnum'''. 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'''. 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 squamous part '''''(pars squamosa)''''' is dorsal to lateral parts and occipital condyles. A nuchal crest is present and is easily palpable. The nuchal crest is often used as a landmark for collection of cerebrospinal fluid (CSF). There are also external occipital protuberances present which provide muscle attachment sites for the nuchal ligament. The lateral parts '''''(partes laterales)''''' form the borders of foramen magnum. '''Occipital condyles''' are present which articulate with the atlas to form the atlanto-occipital joint. The '''paracondylar process''' provide muscle attachment sites for muscles of the head. The '''hypoglossal canal''' is also within this structure. <br> <br> <br>

The occipital bone forms the '''nuchal wall''' and the '''foramen magnum'''. 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'''. 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 squamous part '''''(pars squamosa)''''' is dorsal to lateral parts and occipital condyles. A nuchal crest is present and is easily palpable. The nuchal crest is often used as a landmark for collection of cerebrospinal fluid (CSF). There are also external occipital protuberances present which provide muscle attachment sites for the nuchal ligament. The lateral parts '''''(partes laterales)''''' form the borders of foramen magnum. '''Occipital condyles''' are present which articulate with the atlas to form the atlanto-occipital joint. The '''paracondylar process''' provide muscle attachment sites for muscles of the head. The '''hypoglossal canal''' is also within this structure.

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==== Sphenoid Bone (''os sphenoidale'')  ====

==== Sphenoid Bone (''os sphenoidale'')  ====

The sphenoid bone forms the base of the neurocranium and is composed of a body and wings. The bones are separated by cartilage which ossifies with age. The '''presphenoid (''os praespenoidale'')''' is rostral and has a caudal fossa which is a hollow body with sphenoid sinuses located inside. Within the sinuses are the '''optic chiasma''' and '''optic canal'''. The '''basisphenoid (''os basispenoidalis'')''' is caudal and has a '''median cranial fossa'''. The wings oppose the temporal bone, maxilla, orbit and the brain. The wings also form the '''oval foramen''' and other foramena (see [[Skull and Facial Muscles - Anatomy & Physiology#Species_Differences|species differences]]). The pterygoid processes are also present. <br> <br> <br> <br> <br>

The sphenoid bone forms the base of the neurocranium and is composed of a body and wings. The bones are separated by cartilage which ossifies with age. The '''presphenoid (''os praespenoidale'')''' is rostral and has a caudal fossa which is a hollow body with sphenoid sinuses located inside. Within the sinuses are the '''optic chiasma''' and '''optic canal'''. The '''basisphenoid (''os basispenoidalis'')''' is caudal and has a '''median cranial fossa'''. The wings oppose the temporal bone, maxilla, orbit and the brain. The wings also form the '''oval foramen''' and other foramena (see [[Skull and Facial Muscles - Anatomy & Physiology#Species_Differences|species differences]]). The pterygoid processes are also present. <br> <br> <br> <br> <br>