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==Thoracic Vertebrae==

==Thoracic Vertebrae==

Canines and most mammals have thirteen thoracic vertebrae. Thoracic vertebrae articulate with one another and with the ribs using both cartilaginous and synovial joints (see section above). Thoracic vertebrae are generally very similar throughout the length with only small differences occurring gradually between those vertebrae cranially and caudally. Thoracic vertebrae have short bodies with flattened extremities, short transverse processes and prominent spinous processes. Each body has costal facets which have a synovial joint to articulate with the corresponding rib. These costal facets become more basic the further caudal the vertebrae. The spinous processes reach a maximum height only a few vertebrae behind the cervicothoracic junction and then decline gradually towards the lumbar vertebrae. The orientation of spinous processes shifts from slanting in a general caudal direction for the first eight thoracic vertebrae to slanting in a cranio-dorsal direction for the last few caudal vertebrae.

Canines and most mammals have thirteen thoracic vertebrae. Thoracic vertebrae articulate with one another and with the ribs using both cartilaginous and synovial joints. Thoracic vertebrae are generally very similar throughout the length with only small differences occurring gradually between those vertebrae cranially and caudally. Thoracic vertebrae have short bodies with flattened extremities, short transverse processes and prominent spinous processes. Each body has costal facets which have a synovial joint to articulate with the corresponding rib. These costal facets become more basic the further caudal the vertebrae. The spinous processes reach a maximum height only a few vertebrae behind the cervicothoracic junction and then decline gradually towards the lumbar vertebrae. The orientation of spinous processes shifts from slanting in a general caudal direction for the first eight thoracic vertebrae to slanting in a cranio-dorsal direction for the last few caudal vertebrae.

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===Ribs===

===Ribs===

[[File:Dog ribs.JPG|thumb|right|300px|'''Canine ribs & Sternum''' - Kirill Tsukanov, Moscow State University, 12/04/12]]

[[File:Dog ribs.JPG|thumb|right|300px|'''Canine ribs & Sternum''' - Kirill Tsukanov, Moscow State University, 12/04/12]]

The ribs are paired structures that articulate with a two ribs - the corresponding thoracic vertebrae and also partially with the vertebrae directly caudal. It is the caudal vertebrae that has the same numerical designation as the rib.  An individual rib is composed of a number of elements. Dorsally the rib has a tubercle, head and neck. The head of the rib is rounded with two facets, each of which represents the surface which articulates with the vertebral body. The area between the two facets is referred to as the ''crest'' and allows the attachment of the intercapital ligament. The tubercle of the dorsal rib can act as a further third articular facet in more caudal ribs with the transverse processes. The main body of the rib is long and curved and the lateral surface of the rib is often flattened. The highest degree of curvature of the rib is just ventral to the dorsal neck of the rib and is known as the ''angle''. The angle allows the attachment of the iliocostalis muscles whilst the cranial and caudal edges of the rib allow attachment of the intercostal muscles. The caudal aspect of the body of the rib also contains a small groove which is designed to afford protection to the neurovascular bundle that runs along the length of each rib. At the ventral third of each rib the bone structure of the rib is replaced with costal cartilage at the costochondral junction. This costal cartilage is more flexible than the bone and progressively ossifies with age. The cartilage is bent in a cranioventral manner before making contact with the sternum which together with the increased flexibility of the cartilage itself provides the thoracic cavity with a wide degree of changes in shape. There are vast differences in the size of rib depending on which number the rib is - the first rib if usually the shortest and articulates with the sternum in a more rigid manner than caudal ribs to act as an anchor on which the other ribs draw for inspiration. Ventrally the cartilaginous element of the rib articulates with the sternum (see section below) in nearly all ribs. The exception are the most caudal ribs in which the cartilaginous ventral element of the rib fails to make contact with the sternum and is referred to as a 'floating' rib.  

The ribs are paired structures that articulate with two ribs - the corresponding thoracic vertebrae and also partially with the vertebrae directly caudal. It is the caudal vertebrae that has the same numerical designation as the rib.  An individual rib is composed of a number of elements. Dorsally the rib has a tubercle, head and neck. The head of the rib is rounded with two facets, each of which represents the surface which articulates with the vertebral body. The area between the two facets is referred to as the ''crest'' and allows the attachment of the intercapital ligament. The tubercle of the dorsal rib can act as a further third articular facet in more caudal ribs with the transverse processes. The main body of the rib is long and curved and the lateral surface of the rib is often flattened. The highest degree of curvature of the rib is just ventral to the dorsal neck of the rib and is known as the ''angle''. The angle allows the attachment of the iliocostalis muscles whilst the cranial and caudal edges of the rib allow attachment of the intercostal muscles. The caudal aspect of the body of the rib also contains a small groove which is designed to afford protection to the neurovascular bundle that runs along the length of each rib. At the ventral third of each rib the bone structure of the rib is replaced with costal cartilage at the costochondral junction. This costal cartilage is more flexible than the bone and progressively ossifies with age. The cartilage is bent in a cranioventral manner before making contact with the sternum which together with the increased flexibility of the cartilage itself provides the thoracic cavity with a wide degree of changes in shape. There are vast differences in the size of rib depending on which number the rib is - the first rib if usually the shortest and articulates with the sternum in a more rigid manner than caudal ribs to act as an anchor on which the other ribs draw for inspiration. Ventrally the cartilaginous element of the rib articulates with the sternum (see section below) in nearly all ribs. The exception are the most caudal ribs in which the cartilaginous ventral element of the rib fails to make contact with the sternum and is referred to as a 'floating' rib.  

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===Sternum===

===Sternum===

The sternum represents the bony structure that runs ventrally along the thoracic cavity and provides attachment for the ribs and an anchor for some of the muscles involved in respiration. The sternum is composed of three elements; the '''manubrium''', the '''body''' and the '''xiphoid'''. The '''manubrium''' in canines is rod-shaped and projects cranially to the first rib and unless the dog is particularly well muscles, it can often be palpated at the region of the ventral neck. The body of the sternum is composed of numerous segments interconnected by the costochondral ventral aspects of the ribs (see section above) via small depressions in the segments. These segments are referred to as ''sternebrae'' and are cartilaginous in young canines and ossify with age. The body of the sternum in dogs is generally cylindrical in shape. The '''xiphoid''' cartilage extends caudally in a similar manner to that of the manubrium cranially. It provides attachents for the most cranial aspects of the abdomen and also for the ''linea alba''.

The sternum represents the bony structure that runs ventrally along the thoracic cavity and provides attachment for the ribs and an anchor for some of the muscles involved in respiration. The sternum is composed of three elements; the '''manubrium''', the '''body''' and the '''xiphoid'''. The '''manubrium''' in canines is rod-shaped and projects cranially to the first rib and unless the dog is particularly well muscled, it can often be palpated at the region of the ventral neck. The body of the sternum is composed of numerous segments interconnected by the costochondral ventral aspects of the ribs (see section above) via small depressions in the segments. These segments are referred to as ''sternebrae'' and are cartilaginous in young canines and ossify with age. The body of the sternum in dogs is generally cylindrical in shape. The '''xiphoid''' cartilage extends caudally in a similar manner to that of the manubrium cranially. It provides attachents for the most cranial aspects of the abdomen and also for the ''linea alba''.

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The acetabulum is contributed to by all of the above bones. The acetabulum is surrounded by an ''acetabular rim'' and the depth of the acetabulum varies depending on breed, shape of pelvis and hip conformation.

The acetabulum is contributed to by all of the above bones. The acetabulum is surrounded by an ''acetabular rim'' and the depth of the acetabulum varies depending on breed, shape of pelvis and hip conformation.

===Pelvic Girdle===

===Pelvic Girdle===

In canines the wings of the ilium are much more oblique conformation when compared to large animals and this allows the muscles of the pelvis floor to be displaced laterally over a wider area when compared to the vertebral column. This increases the efficiency and therefore power of the abdominal muscles which allows a greater degree of flexibility of the vertebral column which is essential for faster locomotion and agility. Canines also have relatively caudal displaced ''ishial tuber'' which increases the leverage of the hamstring muscles onto the hindlimbs providing further efficiency improvements for locomotion.

In canines the wings of the ilium have a much more oblique conformation when compared to large animals and this allows the muscles of the pelvis floor to be displaced laterally over a wider area when compared to the vertebral column. This increases the efficiency and therefore power of the abdominal muscles which allows a greater degree of flexibility of the vertebral column which is essential for faster locomotion and agility. Canines also have relatively caudally displaced ''ishial tuber'' which increase the leverage of the hamstring muscles onto the hindlimbs providing further efficiency improvements for locomotion.

=Forelimb=

=Forelimb=

[[File:Dog fore limb 1.JPG|thumb|centre|350px|Canine Forelimb, Moscow State University Department of Biology, Kirill Tsukanov, 2012]]

[[File:Dog fore limb 1.JPG|thumb|centre|450px|Canine Forelimb, Moscow State University Department of Biology, Kirill Tsukanov, 2012]]

==Proximal Forelimb & Shoulder==

==Proximal Forelimb & Shoulder==

===Scapula===

===Scapula===

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====Tibia & Fibula====

====Tibia & Fibula====

Moving distally the stifle allows articulation between the '''tibia'''. The tibia has intimately related to the fibula which is a much smaller bone that runs parallel to the tibia. The tibia is medial to the fibula and effectively excludes the fibula from articulating with the femur. Proximally the tibia has two condyles to facilitate articulation wioth the femur. These condyles are seperated by a ''caudal popliteal notch'' that allows insertion of the popliteal muscle. The articular surfaces of the tibial condyles correspond to the condyles of the distal femur. The articular surface of the tibia also has small depressions and ridges that allow cruciate ligament attachment within the joint. Slightly distal to the tibial condyles and on the cranial aspect is the large and prominent ''tibial tuberosity'' which is continued distally on the cranial aspect of the tibia via the ''tibial crest'' which gradually reduces distally. Proximally and caudally, the articular surface of the tibia also proves a small facet for articulation with the fibula. The shape of the tibia proximally is triangular in cross-section but distally the tibia becomes more craniocaudally compressed. The distal point of the tibia has an articular surface called the ''cochlea'' which facilitates movement with the ''trochlea'' of the '''talus'''. The cochlea has a central bony prominence which is flanked medially and laterally with grooves. The medial cochlea has a bony salience called the ''medial malleolus''.  

Moving distally the stifle allows articulation between the '''tibia'''. The tibia has intimately related to the fibula which is a much smaller bone that runs parallel to the tibia. The tibia is medial to the fibula and effectively excludes the fibula from articulating with the femur. Proximally the tibia has two condyles to facilitate articulation with the femur. These condyles are seperated by a ''caudal popliteal notch'' that allows insertion of the popliteal muscle. The articular surfaces of the tibial condyles correspond to the condyles of the distal femur. The articular surface of the tibia also has small depressions and ridges that allow cruciate ligament attachment within the joint. Slightly distal to the tibial condyles and on the cranial aspect is the large and prominent ''tibial tuberosity'' which is continued distally on the cranial aspect of the tibia via the ''tibial crest'' which gradually reduces distally. Proximally and caudally, the articular surface of the tibia also provides a small facet for articulation with the fibula. The shape of the tibia proximally is triangular in cross-section but distally the tibia becomes more craniocaudally compressed. The distal point of the tibia has an articular surface called the ''cochlea'' which facilitates movement with the ''trochlea'' of the '''talus'''. The cochlea has a central bony prominence which is flanked medially and laterally with grooves. Medially the cochlea has a bony salience called the ''medial malleolus''.  

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====Phalanges====

====Phalanges====

The bone anatomy of the hindlimb phalanges is identical to that of the forelimbs and therefore has not been repeated here. For more detailed anatomy of the phalanges, please see the forelimb distal limb section above.

The bone anatomy of the hindlimb phalanges is identical to that of the forelimbs and therefore has not been repeated here. For more detailed anatomy of the phalanges, please see the forelimb distal limb section above.