Vertebrae
Lateral and corresponding orthogonal projections. Additional projections and schematic drawings as indicated.
Cervical, including hyperextended, hyperflexed with schematic drawings: Figures 304–322
Figure 304 Extended lateral projection of cervical vertebrae. Beagle dog 2.5 years old, entire male (Figures 309, 312 and 315 are from the litter mate of this male dog). (Approximately 90% of original size.)
Figure 305 Line drawing of photograph representing radiographic positioning for Figure 304.
Figure 306 Extended lateral projection of cervical vertebrae.
A Skull
1 Occipital bone
2 Occipital condyle
2(a) Rostral edge
3 Tympanic bullae
B Atlas
4 Dorsal arch
5 Lateral vertebral foramen
6 Articular surfaces
6(a) Cranial articular surface or fovea
6(b) Caudal articular surface or fovea
7 Wings; transverse processes
8 Body
C Axis
9 Dens or odontoid peg
10 Cranial articular surface
11 Caudal articular surface
12 Spinous process
13 Transverse processes
D 3rd cervical vertebra
E 4th cervical vertebra
F 5th cervical vertebra
G 6th cervical vertebra. Vertebra may be shorter than adjacent vertebrae
H 7th cervical vertebra
14 Transverse processes
15 Cranial articular surface of 4th cervical vertebra
16 Cranial articular surface of 6th cervical vertebra
17 Caudal articular surface of 3rd cervical vertebra
18 Caudal articular surface of 5th cervical vertebra
19 Spinous process
20 Body
21 Vertebral foramen
21(a) Dorsal margin
21(b) Ventral margin
I 1st thoracic vertebra
J 2nd thoracic vertebra
K 1st rib
L Scapula
Figure 307 Schematic drawing of extended lateral projection of cervical vertebrae to demonstrate the extent of joint capsules of vertebrae.
Joint capsule
Synovial space. With the exception of the first two capsules this space is smaller than drawn.
The first two joint capsules communicate; atlanto-occipital with atlantoaxial.
Figure 308 Schematic drawing of extended lateral projection of cervical vertebrae to demonstrate vertebral ligaments.
1 Lateral atlanto-occipital ligament. Extends to jugular process of occipital bone.
2 Transverse atlantal ligament. Connects both sides of atlantic ventral arch and so serves to hold dens against atlantic ventral arch.
3 Apical ligament of dens. In three sections. Middle section to ventral part of foramen magnum with two lateral pillars. Lateral sections are heavier and attach to occipital bone medially at the caudal parts of occipital condyles.
4 Nuchal ligament
5 Yellow ligament
6 Dorsal longitudinal ligament
7 Ventral longitudinal ligament. Thinner than dorsal ligament.
Intervertebral discs are not shown but are found between the longitudinal ligaments in the intervertebral spaces from 2nd to 3rd cervical vertebrae caudally. Dorsal atlanto-occipital and ventral atlanto-occipital membranes are not shown but act to reinforce the atlanto-occipital joint dorsally and ventrally. Dorsal atlantoaxial membrane is not shown but it is the dorsal fibrous layer of the atlantoaxial joint capsule.
Figure 309 Extended lateral projection of cervical vertebrae in clinically normal dog. Beagle 2.5 years old, entire male (same dog as in Figures 312 and 315). (Approximately 140% of original size.)
Figure 310 Line drawing of photograph representing radiographic positioning for Figure 309.
Figure 311 Extended lateral projection of cervical vertebrae in clinically normal dog.
A Axis
B 3rd cervical vertebra
C 4th cervical vertebra
D 5th cervical vertebra
E 6th cervical vertebra
F 7th cervical vertebra
1 Spinous process. (Process on 3rd cervical vertebra ill defined.)
2 Caudal articular surface
3 Cranial articular surface
4 Vertebral foramen
4(a) Dorsal margin
4(b) Ventral margin
5 Transverse processes
6 Body
7 Cranial ventral margin of foramen
8 Cranial dorsal margin of foramen
Distance between numbers 7 and 8 is the cranial sagittal diameter of the vertebral foramen.
9 Caudal ventral margin of foramen
10 Caudal dorsal margin of foramen
Distance between numbers 9 and 10 is the caudal sagittal diameter of the vertebral foramen.
Sagittal diameter measurements are used to evaluate possible stenosis of foramen. Note that measurements must always be compared cranially to cranially, caudally to caudally, as cranial diameters are often smaller than caudal ones in the normal dog. This is especially true for the more caudal cervical vertebrae.
Evaluation of the relationship between adjacent ventral foramen margins is also valuable. Measuring angles between the margins is important to determine if stenosis is present. Where gross radiographic abnormality is present an obvious dorsal elevation of the cranial margin with respect to the preceding caudal margin is seen.
Note that changes in lateral projection positions of the cervical vertebrae will alter the relationship of all foramina margins, as seen in the radiographic and drawing Figures 312–317.
11 Dorsal extremity of intervertebral disc space
G 1st thoracic vertebra
H 1st rib
I Scapula
Figure 312 Hyperextended lateral projection of cervical vertebrae in clinically normal dog. Beagle dog 2.5 years old, entire male (same dog as in Figures 309 and 315). (Approximately 140% of original size.)
Figure 313 Line drawing of photograph representing radiographic positioning for Figure 312.
Figure 314 Hyperextended lateral projection of cervical vertebrae in clinically normal dog.
Cranial and caudal sagittal diameters are similar to the extended lateral projection of cervical vertebrae, drawing Figure 311.
Cranial and caudal cervical ventral foramen margin angles are the same as in the extended lateral projection of cervical vertebrae drawing, Figure 311.
There are no dorsal elevations of cranial ventral foramen margins.
Figure 315 Hyperflexed lateral projection of cervical vertebrae in clinically normal dog. Beagle dog 2.5 years old, entire male (same dog as in Figures 309 and 312). (Approximately 150% of original size.)
Figure 316 Line drawing of photograph representing radiographic positioning for Figure 315.
Figure 317 Hyperflexed lateral projection of cervical vertebrae in clinically normal dog.
Sagittal diameters and ventral foramen margin angles in extended and hyperextended lateral projections of cervical vertebrae were similar (please see drawings Figures 311 and 314). A marked change is now seen in the hyperflexed lateral projection of cervical vertebrae.
Cranial and caudal cervical ventral foramen margin angles have increased.
There are obvious dorsal elevations of cranial ventral foramen margins at the 3rd, 4th and 5th cervical vertebrae. Dorsal elevations are less obvious at the 6th and 7th cervical vertebrae.
Figure 318 Ventrodorsal projection of cervical vertebrae. Beagle dog 2.5 years old, entire male. (Approximately 80% of original size.)
Figure 319 Line drawing of photograph representing radiographic positioning for Figure 318.
Figure 320 Ventrodorsal projection of cervical vertebrae.
A Skull
1 Squamous part of occipital bone
2 Occipital condyle
B Atlas
3 Cranial articular fovea
4 Caudal articular fovea
5 Dorsal arch
5(a) Cranial border
5(b) Ventral arch caudal border
6 Wing; transverse process
7 Transverse foramen
C Axis
8 Dens
9 Cranial articular surface
10 Caudal articular surface
11 Spinous process
12 Transverse process
D 3rd cervical vertebra
E 4th cervical vertebra
F 5th cervical vertebra
G 6th cervical vertebra
H 7th cervical vertebra
13 Cranial articular surface
14 Caudal articular surface
15 Spinous process
16 Transverse foramen
17 Lateral margin of vertebral foramen
18 Dorsal cranial margin of body
19 Ventral caudal margin of body
I 1st thoracic vertebra
J 1st rib
K Clavicle
L Scapula
M Humerus
Figure 321 Schematic drawing of ventrodorsal projection of cervical vertebrae to demonstrate joint capsules.
Joint capsule and synovial space of vertebral and costal articulations
Atlanto-occipital joint capsule communicates ventromedially with atlantoaxial joint capsule.
a Joint capsule of head of rib
b Joint capsule of tubercle of rib
Figure 322 Schematic drawing of ventrodorsal projection of cervical vertebrae to demonstrate vertebral ligaments
1 Lateral atlanto-occipital ligament
2 Dorsal atlantoaxial ligament
3 Apical ligaments of dens. Centrally attaches to ventral foramen magnum. Laterally attaches to occipital condyles.
4 Transverse atlantal ligament. Passes dorsally over dens. A bursa separates ligament and dens.
5 Positions of dorsal and ventral longitudinal ligaments
6 Yellow ligament. Laterally extends as far as the joint capsules surrounding articular processes. Ventral to ligament is epidural space.
7 Nuchal ligament. Ligament is anatomically in the midline but is illustrated to the right of midline to differentiate it from (5).
8 Supraspinous ligament. Ligament is anatomically in the midline but is illustrated to the right of midline to differentiate it from (5).
Rib ligaments and intervertebral discs not shown.
Thoracic with schematic drawings: Figures 323–334
Figure 323 Lateral projection of thoracic vertebrae. Beagle dog 2.5 years old, entire male. (Approximately 80% of original size.)
Figure 324 Line drawing of photograph representing radiographic positioning for Figure 323.
Figure 325 Lateral projection of thoracic vertebrae with rib shadows excluded for clarity.
A 7th cervical vertebra
B 1st thoracic vertebra
C 2nd thoracic vertebra
D 3rd thoracic vertebra
E 4th thoracic vertebra
F 5th thoracic vertebra
G 6th thoracic vertebra
H 7th thoracic vertebra
I 8th thoracic vertebra
J 9th thoracic vertebra
K 10th thoracic vertebra
L 11th thoracic vertebra. Anticlinal vertebra.
M 12th thoracic vertebra
N 13th thoracic vertebra
1 Spinous process
1(a) Spinous process of anticlinal vertebra. (nearly perpendicular to axis)
3 Cranial articular process
3 Caudal articular process
4 Body
5 Transverse process. Includes mammillary process from 2nd or 3rd thoracic vertebra caudally.
6 Vertebral foramen
6(a) Dorsal margin
6(b) Ventral margin
7 Intervertebral foramen
8 First visible accessory process
9 Mammillary process
O Crura of diaphragm
Figure 326 Schematic drawing of lateral projection of thoracic vertebrae to demonstrate the extent of joint capsules.
Joint capsule and synovial space of vertebral articulation
Joint capsule and synovial space of costovertebral joint. Head of rib.
Joint capsule and synovial space of costovertebral joint. Tubercle of rib.
Figure 327 Schematic drawing of lateral projection of thoracic vertebrae to demonstrate vertebral ligaments.
1 Nuchal ligament
2 Supraspinous ligament
3 Yellow ligament
4 Dorsal longitudinal ligament
5 Ventral longitudinal ligament
Interspinous ligaments and intervertebral discs not shown.
Figure 328 Lateral projection of thoracic vertebrae to demonstrate the rib shadows not seen in Figure 325.
A Scapula
1 Spine
2 Caudal margins of right and left
B 1st rib
C 2nd rib
D 3rd rib
E 4th rib
F 5th rib
G 6th rib
H 7th rib
I 8th rib
J 9th rib
K 10th rib
L 11th rib
M 12th rib
N 13th rib
3 Head
4 Neck
5 Tubercles (right and left)
O Crura of diaphragm
Figure 329 Schematic drawing of lateral projection of thoracic vertebrae to demonstrate rib ligaments.
1 Ligament of head. Extends from head of rib to lateral part of intervertebral disc. Last three ribs are displaced and for these the ligament shifts to attach to the bodies of the vertebrae.
2 Ligament of tubercle. Is distal to articular capsule. Crosses capsule and attaches to transverse process.
3 Ligament of neck. Extends from neck to ventral surface of transverse process plus lateral body of vertebra.
Intercapital ligament not shown but is seen in a similar position as the head ligament. It runs across the ventral vertebral canal, at the level of the intervertebral disc, to attach to the head of the rib on the contralateral side. It is absent from 1st, 12th and 13th ribs.
Figure 330 Ventrodorsal projection of thoracic vertebrae. Beagle dog 2.5 years old, entire male. (Approximately 80% of original size.)
Figure 331 Line drawing of photograph representing radiographic positioning for Figure 330.
Figure 332 Ventrodorsal projection of thoracic vertebrae with ventral shadows of ribs excluded for clarity.
A 7th cervical vertebra
B 1st thoracic vertebra
C 2nd thoracic vertebra
D 3rd thoracic vertebra
E 4th thoracic vertebra
F 5th thoracic vertebra
G 6th thoracic vertebra
H 7th thoracic vertebra
I 8th thoracic vertebra
J 9th thoracic vertebra
K 10th thoracic vertebra
L 11th thoracic vertebra. Anticlinal vertebra.
M 12th thoracic vertebra
N 13th thoracic vertebra
O 1st lumbar vertebra
1 Spinous process of 1st thoracic vertebra. These processes incline caudally from 1st to 10th thoracic vertebrae.
2 Spinous process of 9th thoracic vertebra
3 Spinous process of 10th thoracic vertebra
4 Spinous process of 11th thoracic vertebra
5 Cranial margin of body
6 Caudal margin of body
7 Cranial articular margin of 13th thoracic vertebra
8 Mammillary process (seen as a distinct structure just caudal to the articular margin)
9 Cranial articular margin found near the median plane from thoracic vertebrae 2–10
10 Caudal articular margin of thoracic vertebra
11 Caudal articular margin found near the median plane from thoracic vertebrae 1–9
12 Transverse process
13 Costal fovea of transverse process
14 Body
15 Cranial costal fovea
16 Caudal costal fovea
17 Lateral margin of vertebral foramen
P 1st rib
Q 13th rib
R Diaphragm
Figure 333 Sketch drawing of ventrodorsal thoracic vertebrae to demonstrate anatomically the joint articulations of vertebrae and ribs.
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