Changes

[[Image:Anatomy_and_physiology_of_animals_Regions_of_a_vertebral_column.jpg|thumb|right|250px|Divisions of the spinal cord- Copyright Ruth Lawson Otago Polytechnic ]]

[[Image:Anatomy_and_physiology_of_animals_Regions_of_a_vertebral_column.jpg|thumb|right|250px|Divisions of the spinal cord- Copyright Ruth Lawson Otago Polytechnic ]]

 

==Introduction==

 

=''Introduction''=

The trunk consists of three segments: thorax, abdomen, and pelvis, each of which is bounded by body wall and contains a cavity.  The thoracic cavity lies cranial to the diaphragm, whereas the abdominal cavity lies caudal.  The pelvic cavity is defined by the borders of the bony pelvis and communicates with the abdominal cavity.   

The trunk consists of three segments: thorax, abdomen, and pelvis, each of which is bounded by body wall and contains a cavity.  The thoracic cavity lies cranial to the diaphragm, whereas the abdominal cavity lies caudal.  The pelvic cavity is defined by the borders of the bony pelvis and communicates with the abdominal cavity.   

The ventral and lateral body walls are initally formed by somatopleure (ectoderm and lateral plate mesoderm), but is later invaded by somitic cells migrating ventrally.  These differentiate to form ribs and sternum and associated muscles.

The ventral and lateral body walls are initally formed by somatopleure (ectoderm and lateral plate mesoderm), but is later invaded by somitic cells migrating ventrally.  These differentiate to form ribs and sternum and associated muscles.

=''Divisions and Landmarks''=

==Divisions and Landmarks==

The common pattern of canine landmarks, according to Dyce, Sack, et al, can be quantified as such:

The common pattern of canine landmarks, according to Dyce, Sack, et al, can be quantified as such:

[[Image:Spinal landmarks.jpg|center|500px|Spinal Landmarks - Copyright Becky Pocock 2008]]

[[Image:Spinal landmarks.jpg|center|500px|Spinal Landmarks - Copyright Becky Pocock 2008]]

=''Vertebrae and Joints''=

==Vertebrae and Joints==

[[Image:Cervical Vertebra.png|thumb|right|150px|Cervical Vertebra - Wikimedia Commons 2008]]

[[Image:Cervical Vertebra.png|thumb|right|150px|Cervical Vertebra - Wikimedia Commons 2008]]

*Vertebrae consist of a body which encloses the vertebral foramen (through which the spinal cord and meninges run), a spinous process, and a transverse process, as well as articular processes by which they join together

*Vertebrae consist of a body which encloses the vertebral foramen (through which the spinal cord and meninges run), a spinous process, and a transverse process, as well as articular processes by which they join together

*The form of the spinous process varies with respect to species and region

*The form of the spinous process varies with respect to species and region

 

===Cervical Vertebrae===

 

 

 

 

==Cervical Vertebrae==

*The first two cervical vertebrae are known as the '''atlas''' and the '''axis''' respectively, and are modified to allow movement of the head

*The first two cervical vertebrae are known as the '''atlas''' and the '''axis''' respectively, and are modified to allow movement of the head

**The atlas has no conventional body: instead it is composed of two lateral masses joined by dorsal and ventral arches

**The atlas has no conventional body: instead it is composed of two lateral masses joined by dorsal and ventral arches

*The last (C7) cervical vertebra has a taller spinous process than those proceeding it, and articulates with the first pair of ribs

*The last (C7) cervical vertebra has a taller spinous process than those proceeding it, and articulates with the first pair of ribs

==Thoracic Vertebrae==

===Thoracic Vertebrae===

*Thoracic vertebrae articulate with the ribs

*Thoracic vertebrae articulate with the ribs

*They are distingushed by short bodies with flattened extremities, costal facets, short transverse processes, and prominent spinous processes

*They are distingushed by short bodies with flattened extremities, costal facets, short transverse processes, and prominent spinous processes

*The orientation of spinous processes shifts from caudo- to craniodorsal

*The orientation of spinous processes shifts from caudo- to craniodorsal

==Lumbar Vertebrae==

===Lumbar Vertebrae===

*Longer and more uniform in shape than thoracic vertebrae

*Longer and more uniform in shape than thoracic vertebrae

*Shorter in height, with long, flattened transverse processes that project laterally

*Shorter in height, with long, flattened transverse processes that project laterally

==Sacral Vertebrae==

===Sacral Vertebrae===

*'''Sacrum''': a single bone formed by the fusion of several vertebrae that articulates with the pelvic girdle

*'''Sacrum''': a single bone formed by the fusion of several vertebrae that articulates with the pelvic girdle

*Allows the thrust of the hindlimbs to be transmitted to the trunk

*Allows the thrust of the hindlimbs to be transmitted to the trunk

*Narrows caudally and is curved to present a concave surface to the pelvic cavity

*Narrows caudally and is curved to present a concave surface to the pelvic cavity

==Caudal Vertebrae==

===Caudal Vertebrae===

*Number varies greatly even within species

*Number varies greatly even within species

*Progressive simplification of form

*Progressive simplification of form

==Joints of the Spinal Column==

===Joints of the Spinal Column===

*Two types of joints:

*Two types of joints:

**Cartilaginous: direct connections between vertebral bodies

**Cartilaginous: direct connections between vertebral bodies

****Movement is rotational about a longitudinal axis (eg. head shaking)

****Movement is rotational about a longitudinal axis (eg. head shaking)

=''Spinal Cord''=

==Spinal Cord==

The details of the spinal cord are found [[Spinal Cord - Anatomy & Physiology|here]].

The details of the spinal cord are found [[Spinal Cord - Anatomy & Physiology|here]].

=''Hypaxial and Epaxial Muscles''=

==Hypaxial and Epaxial Muscles==

[[Image: epaxial muscles.JPG|thumb|right|150px|Epaxial muscles- Copyright C. Clarkson and T.F. Fletcher, University of Minnesota]]

[[Image: epaxial muscles.JPG|thumb|right|150px|Epaxial muscles- Copyright C. Clarkson and T.F. Fletcher, University of Minnesota]]

[[Image: hypaxial muscles.JPG|thumb|right|150px|Hypaxial muscles- Copyright C. Clarkson and T.F. Fletcher, University of Minnesota]]

[[Image: hypaxial muscles.JPG|thumb|right|150px|Hypaxial muscles- Copyright C. Clarkson and T.F. Fletcher, University of Minnesota]]

[[Category:Musculoskeletal System]]

[[Category:Musculoskeletal System - Anatomy & Physiology]]