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Skull and Facial Muscles - Anatomy & Physiology (view source)
Revision as of 18:15, 23 January 2011
, 18:15, 23 January 2011→Bones of the Skull
[[Image:Pig skull dorsal.jpg|thumb|right|150px|Pig skull (nuchal crest, nasal bone, frontal bone, pareital bone, zygomatic process of the temporal bone and coronoid process of the mandible labelled) - Copyright nabrown RVC]]
[[Image:Pig skull dorsal.jpg|thumb|right|150px|Pig skull (nuchal crest, nasal bone, frontal bone, pareital bone, zygomatic process of the temporal bone and coronoid process of the mandible labelled) - Copyright nabrown RVC]]
===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. Paracondylar process provide muscle attachment sights for muscles of the head. The hypoglossal canal is also within this structure.
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 sights 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)===
[[Image:Pig skull ventral view.jpg|thumb|right|150px|Ventral view pig skull (vomer, occipital condyle, sphenoid, pterygoid bone, hamulus labelled)- Copyright nabrown RVC]]
[[Image:Pig skull ventral view.jpg|thumb|right|150px|Ventral view pig skull (vomer, occipital condyle, sphenoid, pterygoid bone, hamulus labelled)- Copyright nabrown RVC]]
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 foramen (see [[Skull and Facial Muscles - Anatomy & Physiology#Species Differences|species differences]]) including the '''carotid notch, oval foramen''' and '''spinous notch''' (in the horse). The pterygoid processes are also present.
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===Temporal Bone (os temporale)===
The temporal bone is composed of '''squamous, petrosal''' and '''tympanic''' parts and forms the lateral wall of the cranial cavity. It articulates with the frontal, pareital and sphenoid bones.
[[Image:Zygomatic arch.jpg|thumb|right|150px|Zygomatic Arch (Dog) - Copyright nabrown RVC]]
[[Image:Zygomatic arch.jpg|thumb|right|150px|Zygomatic Arch (Dog) - Copyright nabrown RVC]]
The squamous element joins the temporal process of the zygomatic bone to form the '''zygomatic arch''' and forms the articulating surface of the '''[[Mastication#Jaw Articulation|temporomandibular joint]]'''. An '''articular tubercle''' and '''mandibular fossa''' are present. Occipital process and retrotympanic processes surround the '''external acoustic meatus''' whilst the petrosal part encloses the inner ear internally via the '''internal acoustic meatus'''. Ventrally this structure forms the '''mastoid process'''. The '''styloid process''' attaches the '''[[Hyoid Apparatus - Anatomy & Physiology|hyoid apparatus]]''' and a '''stylomastoid foramen''' is also present. The tympanic part is the ventral section of the temporal bone containing the '''tympanic bulla'''. The '''tympanic membrane''' separates tympanic cavity from '''external acoustic meatus''' and encloses the '''auditory ossicle''' dorsally. The musculotubal canal contains tensors of the [[Soft Palate#Musculature and Innervation|soft palate]].
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'''Frontal Bone (os frontale)'''
'''Frontal Bone (os frontale)'''