Bones of the Axial Skeleton Flashcards
1
Q
What are the 2 regions of the skeleton?
A
Axial and appendicular
2
Q
What are the 6 parts of the axial skeleton?
A
- skull
- vertebral column
- ribs
- sternum/ breast bone
- hyoid bone/tongue bone
- Ossicles (tiny bones in the middle ear)
3
Q
The appendicular skeleton consists of the:
A
girdles and limbs of the thoracic and pelvic regions
4
Q
What are the 5 segments of the vertebral column, and how many bones are in each segment?
A
- cervical (7)
- thoracic (13)
- lumbar (7)
- sacral-fused (3)
- coccygeal (20-23)
These numbers apply to some carnivores, but varies among species
5
Q
What are the 4 functions of the axial skeleton?
A
- Provides attachment for the ribs and back muscles
- Supports trunk
- Carries skull
- Protects spinal cord
6
Q
What 3 movements happen in the axial skeleton?
A
- flexion (hypaxial muscles)
- extension (epaxial muscles)
- lateral flexion
the shape of the skeleton limits movement
7
Q
Every vertebra consits of what 4 parts?
A
- Body
- Arch
- Process
- Foramen
8
Q
What type of bone shape are vertebrae?
A
irregular (ossa irregularia)
9
Q
What are 5 examples of common diseases associated with the axial skeleton?
A
- IVDD: degenerative disease that results in compression of the spinal cord and nerves
- Spondylosis: degenerative disease that affects the joints
- Spondylitis: infection of the intervertebral discs
- Spinal trauma
- Cancer
10
Q
The number of vertebrae in each segment of the vertebral column tends to vary among species, but which segment is the most consistent?
A
Cervical; almost always 7
11
Q
What two muscle groups are associated with the vertebral column?
A
Epaxial and hypaxial muscle groups
12
Q
What is the common basic structure of all vertebrae?
A
Spongy bone covered with a thin layer of compact bone
13
Q
What are the characteristics of the vertebral body?
A
- prismatic or cylindrical ventral portion on which the other parts are constructed
- has a convex cranial and concave caudal extremity, which are covered by a plate of hyaline cartilage
- longitudinal grooves on the dorsal aspect and foramina on either side of the grooves
- intervertebral cartilaginous discs are interposed between adjacent vertebrae
- the ventral surface carries the ventral crest, which varies in size in the different regions of the vertebral column
14
Q
What are the characteristics of the vertebral arch?
A
- also called neural arch, forms over the dorsal surface of the body
- made up of two lateral pedicles and a dorsal plate
- arch + vertebral body = vertebral foramina
15
Q
What are the characteristics of intervertebral foramina?
A
- opening formed by the fusion of the arch and body of the vertebrae
- correspond with the foramina of adjacent vertebrae to for the vertebral canal through which the spinal cord passes
16
Q
What are the characteristics of the vertebral canal?
A
- made up of the foramina of adjacent vertebrae with the spinal cord passing through
- greatest at the level of the first and second cervical vertebrae, reduced in width throughout the cervical spine, increases again in the cranial thoracic region, and becomes narrower in the caudal thoracic region
- diameter widens again in the lumbar region and gradually becomes narrower at the level of the first caudal vertebrae
- contains spinal cord, nerves, meninges, blood vessels, ligaments, fat, and CT
17
Q
Do all vertebrae have the same characteristics?
A
No; vertebrae of different regions have to fulfill different functions and therefore have different characteristics
18
Q
What are the general characteristics of the cervical vertebrae?
A
- cranial-most region of the vertebral column
- C1, and C2 are very unique, but otherwise they all have cylindrical bodies that articulate with one another at specialized fibrocartilaginous joints called intervertebral discs
- C1 and C2 are highly modified to allow free movement of the head
- C3-C7 are similar with increasing elongation of the spinous processes
- C1-C6 have transverse foramen that all associate with one another to form the transverse canal through which the vertebral artery, nerve, and veins pass
- intervertebral foramen exist between the articulation of different vertebrae are where the spinal nerves exit from with the exception of C1
19
Q
What is the name of the joint that permits the “yes” motion of the head, and what two bones form it?
A
- atlantoccipital joint
- formed between the skull and C1(atlas)
20
Q
What is the name of the joint that permits the “no” motion of the head, and what two bones come together to form it?
A
- atlantoaxial joint
- between C1 and C2
bodies articulate to form fibrocartilaginous joint and the arches articulate to form synovial zygapophyseal joint
21
Q
What is the name of C1 and its characteristics
A
- Atlas bone
- supports the weight of the head
- significantly reduced body compared to the other cervical vertebrae
- on other vertebrae, the body is thicker than the arch, but they are about the same size in the atlas
- spinal nerves of C1 exit through the lateral vertebral foramen rather than the intervertebral foramen
- has two wings (ala) that are palpable and a good way to distinguish it from other vertebrae
22
Q
What is the name and characteristics of C2
A
- axis bone
- responsible for rotational movement of the head
- spool shaped body
23
Q
In what species is there a tubercle between the transverse processes of C1 and C2
A
swine
24
Q
How do the odontoid process and dens articulate on the axis bone
A
have separate ossification centers and they fuse to form one structure
25
How are the cervical vertebrae distinguished on a radiograph?
increasing elongation of spinous processes with increasing radiopacity as you move caudally
## Footnote
radiopacy= the relative inability of electromagnetic radiation to pass through a particular material (the bigger/thicker an objet is, the more radiation is absorbed so visibility on xray is increased)
26
What are the unique characteristics of C7
- no transverse foramen (still has transverse process)
- tallest spinous process of the cervical verteberae
- smallest transverse process of the cervical vertebrae with no ventral crest
- only cervical vertebrae with a caudal costal fovea for articulation with the first rib
27
what is superimposition and where does it occur
- when two or more bones overlap each other on a radiograph
- happens with C7-T3 due to overlapping of the scapula
- happens with caudal lumbar vertebrae and sacrum due to the pelvis overlapping
28
Where is the most common place for vertebral subluxation
| occurs when a bone is partially pulled or pushed out of place
Atlantoaxial joint;
due to it having one of the highest degrees of movement, causing head stiffness
29
What are the general characteristics of thoracic vertebrae
- short bodies with very tall spinous processes that are directed dorsally
- each of the thoracic vertebrae has three costal fovaea for articulation with the ribs (cranial, caudal, and transverse)
- vary in number among species but we generally expect 13
- T11 is the most important
30
What are the unique characteristics of T11
- called the anticlinal vertebra
- transition point on radiograph to help identify where lesions may be on the spinal cord due to its nearly perpendicular spinous process
- T1-T10 have caudally pointed spinous processes that shorten as they progress caudally and T12-T13 have cranial pointing spinous processes
31
What vertebrae in horses and cattle are equal to T11 in dogs?
- horses: T16
- cattle: T11-T13
32
What are the important processes to be able to identify on T11 that are also present on lumbar vertebrae
| 2
Mammillary and accessory processes
33
What are the general characteristics of lumbar vertebrae
- have prominent plate-like transverse processes that project laterally and attach to the body of the vertebrae
- have mammillary and accessory processes
34
Explain how the mammillary and accessory processes are used as landmarks in surgery
the vertebral arch is divided into a dorsal laminae half and a ventrolateral pedicle half. In spinal stabilization surgery, you want to place the screw in between both processes through the pedicle half to avoid accidentally damaging the spinal cord
35
What are the 5 ligaments to know in the spinal column?
- **supraspinous** ligament: runs on top of the spinous processes
- **interspinous** ligament: in between the spinous processes
- **interarcuate** ligament: in between the dorsal aspect of adjacent arches
- **dorsal longitudinal** ligament: overtop of the bodies at the base of the arch just dorsal to the IVD
- **ventral longitudinal** ligament: at the base of the bodies just ventral to the IVD
36
What are the characteristics of the sacrum?
- composed of three fused sacral vertebrae
- articulates with the pelvis
- intervertebral discs of these vertebrae are fused within the sacrum
- processes fuse to form crests
- promontory on the cranial end forms the boundary of the pelvic inlet along with the ilium
- sacral foramina located on the dorsal and ventral (pelvic) surfaces that are the result of the fusion of the intervertebral foramina where the first and second sacral spinal nerves exit from
- wings on either side that project laterally and have a rough auricular surface on the dorsal side that articulates with the sacropelvic surface of the ilium
37
At what ages does the fusion of the sacral vertebrae occur in dogs/pigs, ruminants, and horses
- dogs/pigs: 1.5 years
- ruminants: 3-4 years
- horses: 4-5 years
38
What are the names of the 3 fused processes on the sacrum?
- **median sacral crest**- fusion of*spinous* processes
- **lateral sacral crests**- fusion of*transverse* processes
- **intermediate sacral crests**- fusion of *articular* processes situated between the crests
39
What are the two important ligaments associated with the sacrum?
- **sacrotuberous** ligament: extends from the sacrum to the ischiatic tuberosity and creates the greater and lesser ischiatic foramen
- **sacroiliac** ligament: important in cases of trauma or dislocation of the joint between the ilium and sacrum; stabilizes the trunk of the hindlimbs
40
What are the wings of the sacrum landmarks for clinically?
landmark for the **collection of cerebral spinal fluid** from the lumbosacral space where they articulate with the wings of the ilium
41
What are the 4 components of the thoracic cage?
- all vertebrae that articulate with ribs (C7-L1)
- ribs
- costal cartilage
- sternum
42
What is the thoracic cavity?
empty area inside the thoracic cage where the viscera is held
43
What is the thorax?
the entire region of the thoracic cage including the viscera, skin, and muscles
44
What is the thoracic cage?
skeletal framework that is formed by the bones of the thorax
45
How many pairs of ribs are typically present in an animal
13
46
What are the 2 parts of the rib?
* dorsal bony region
* ventral cartilaginous region
the 2 meet at an area referred to as the costochondral junction
47
What is the cartilaginous region of the ribs referred to as?
costal cartilages
48
What do the costal cartilages of the 10th-12th ribs form?
costal arch
| area in yellow
49
What are sternal/true ribs?
The first 9 pairs of ribs that articulate directly with the sternum
50
What are asternal/false ribs?
10th-12th ribs that articulate with the sternum via the costal arch
51
What is a free-floating rib?
The 13th rib that is not connected to the sternum but is free-floating in the musculature
52
What is the best way to orient yourself with the direction of the rib?
| cranial border is ___, caudal border is _____
the cranial border is convex and the caudal border is concave
| same as vertebral body
53
What are the characteristics of the sternum/breast bone? (What are the 3 segments, and what does it articulate with?)
- made up of 3 segments:
- manubrium (cranially)
- body
- xiphoid process (caudally)
- 8 bones called sternebrae
- articulate with the first 9 ribs and costal arch on the distal end of the asternal ribs
54
What are the characteristics of the caudal vertebrae
- gradually reduce in size from first to last
- progressive simplification in terms of size and processes as you move caudally
- the last caudal vertebrae has almost no defining features; just a cylindrical rod-shaped bone
- between 20-24 in number
- spinous process of the second caudal vertebrae is bifurcated in horses
- arch becomes incomplete at the 3rd caudal vertebra, leaving the canal open
- transverse process is significantly lost at the 7th caudal vertebra and from Ca8 on there is only a bony ridge left
- hemal arch from Ca4-Ca6 provides passage for caudal vessels and protects the vasculature
55
Describe intervertebral discs:
- between the bodies of each vertebrae
- fibrocartilaginous discs that appear radiolucent on radiographs
- inner layer called the nucleus pulposus that is jelly-like and mainly made of water and collagen fibers
- nucleus pulposus is surrounded by an outer ring called the anulus fibrosus
56
What is a herniation of an intervertebral disc?
- when part of the nucleus pulposus slips out and herniates, putting pressure on the spinal cord
- most common cause of back pain in dogs, especially dachshunds
57
What is spina bifida?
- **absence of vertebral arch** leaving **spinal cord exposed**
- causes paralysis, weakness, lack of movement, and fecal/urinary incontinence
58
What is responsible for extreme flexibility in felines?
| What 3 ligaments are absent?
- much larger degree of flexibility of the anulus fibrosis
- extra lumbar and thoracic vertebrae
- no **supraspinous ligament**
- no **nuchal ligament**
- no **sacrotuberous ligament**
59
What aspect of vertebrae limits their movement?
their shape
60
What is the fovea dentis of C1
Point of articulation for the dens on C2
61
What are the lateral vertebral foramen of C1 and what is their function
Holes on the craniolateral margin of C1 through which the **first cervical nerve** passes
62
What are the caudal articular fovea of C1 and what is their function
2 shallow caudal articular fovea that articulate with the cranial end of the body of C2 to form a synovial joint that permits rotation
63
Where is the ventral tubercle of C1 located
Caudal ventral projection
64
Where are the wings of the Atlas located
Broad and flat on either side of the vertebral body
65
What are the characteristics of the wings of the atlas
- also called ala
- palpable in animals in a good way to distinguish C1 from other vertebrae
- broad and flat on both sides of the vertebral body
- palpable landmark for the collection of CSF through the atlantooccipital space or the atlantoaxial space along with the occipital protuberance on the skull
66
where are the alar notches of C1 located and what is their function
notches on either side of the wings on the cranial side at the junction between the wing and the arch that the vertebral artery passes through
67
The vertebral body has a ______ cranial and _______ caudal extremity, which are covered by a plate of ______ cartilage
convex cranial; concave caudal; hyaline cartilage
68
- prismatic or cylindrical ventral portion on which the other parts are constructed
- longitudinal grooves on the dorsal aspect and foramina on either side of the grooves
- intervertebral cartilaginous discs are interposed between adjacent vertebrae
- the ventral surface carries the ventral crest, which varies in size in the different regions of the vertebral column
69
How is the alar notch in dogs different from other species
in dogs they are notches
in some other species they are closed off to form alar foramen that the vertebral arteries pass through
70
Where are the transverse foramen on C1 located and which artery passes through them?
On the caudal half of each wing that the vertebral artery passes through
71
What species lack transverse foramen on C1?
ruminants
72
What does the Atlas have in place of a spinous process?
**Dorsal tubercle** on the cranial margin of the vertebral arch that is occasionally bifid
73
What is the identifier for the axis bone on the cranial aspect of the body?
Odontoid process that fuses with the dens and articulates with the fovea dentis on C1
74
What are the caudal articular processes of C2 and what is their function?
Processes on either side of the spinous process of C2 that articulate with C3 to form the synovial joint
| dorsal view
75
Where is the spinous process of C2 located?
Flat and elongated similar to the wings of the atlas
- located dorsally
76
Where are the transverse processes of C2 located?
Where the arch meets the body on either side and project Caudally
77
Where are the transverse foramen of C2 located and what passes through them?
On the **caudal** aspect of each transverse process; **vertebral artery** passes through the transverse foramen of C2 and C1 creating the transverse canal
| caudal view
78
What is the transverse canal of the vertebrae? What passes through it?
The summation of the transverse foramen C1-C6
vertebral artery, vein, and nerves passed through
79
What is the purpose of intrevertebral foramen and and which vertebrae do not have these foramen?
Intervertebral foramen exist between the articulation of different vertebrae
- provide the location through which the spinal nerves exit
- C1 & L1-5 do not have intraver
- in these cases, spinal nerves exit from the lateral vertebral foramen instead
80
Describe mammillary processes of vertebrae
- knob-like dorsal projection of the transverse processes of T2-T10 and the cranial articular processes of T11-caudal vertebrae
- epaxial mm. of the transversospinalis system attach to these processes
- landmark for the placement of screws in spinal surgery
81
Describe accessory processes
- from mid-thoracic vertebrae to L5 or L6
- in carnivores and pigs go from T3 to lumbar region
- located at the base of the transverse process with variation in attachment points based on species
- project caudally
82
Where is the median sacral crest of the sacrum located? What fuses to form it?
forms from fusion of **spinous processes** of **sacral vertebrae**
83
Where is the lateral sacral crest located? What fuses to form it?
fusion of **transverse processes** of sacral vertebrae
84
Where are the intermediate sacral crests located? What fuses to form these?
fusion of the **articular processes** of the sacral vertebrae
85
Where are the sacral foramina located? Which spinal nerves exit through them?
dorsal and ventral foramen
* 1st and 2nd sacral spinal nerves exit from
86
Where are the wings of the sacrum located?
- on either side of the cranial half of the sacrum that project laterally
- have a rough auricular surface on the dorsal side where they articulate with the sacropelvic surface of the ilium
- quadrilateral shape in dogs, triangular in other species
87
What are the characteristics of intervertebral foramen?
- located at the lateral aspect of each vertebra
- formed by the notches of the cranial and caudal adjacent vertebrae
- circular or oval shaped and generally larger than interarcuate spaces
- each foramina has ventral and dorsal branches of spinal nerves exiting from them as well as vertebral arteries entering to supply the meninges of the spinal cord
88
The vertebral arch is also known as the ______ and forms over the _____ surface of the body.
neural arch; dorsal
89
The vertebral body is ______ cranially and _____ caudally.
convex cranially; concave caudally
90
Each vertebra carries a number of processes for the attachment of ______ and _______ and for the articulation with ____ ____.
muscles and ligaments; for the articulation with adjacent vertebrae
91
There are ____ articular processes positioned cranial and caudal to the root of the spinous process.
four
| 2 cranial, 2 caudal (1 on each side),
92
There is ______ dorsal/spinous process at the mid-dorsal line of the arch.
one
93
There are ___ transverse processes projecting laterally from the base of the arch
two
94
There are ___ mammillary processes between the transverse and cranial articular processes on the thoracic and lumbar vertebrae.
two
95
Which is the only cervical vertebrae with a caudal costal fovea? (for articulation with the first rib)
C7
96
What 7 things does the vertebral canal consist of?
- spinal cord
- nerves
- meninges
- blood vessels
- ligaments
- fat
- CT
97
Each of the thoracic vertebrae has three ____ ____ for articulation with the ribs (cranial, caudal, and transverse)
costal fovea
98
Which vertebra is also called the anticlinal vertebra?
T11
99
Which ligament runs on top of the spinous processes?
supraspinous ligament
100
Which ligament runs in between the spinous processes?
interspinous ligament
101
Which ligament runs in between the dorsal aspect of adjacent arches?
interarcuate ligament (ligamenta flavum)
102
Which ligament runs overtop of the bodies at the base of the arch just dorsal to the IVD
dorsal longitudinal ligament
103
Which ligament runs at the base of the bodies just ventral to the IVD
ventral longitudinal ligament
104
The dorsal head of the ribs points ______ and articulates with the ____ ______ of the vertebrae
caudally; art. /w/ costal fovea of the vertebrae
105
The tubercle of the rib articulates with the:
transverse costal fovea
106
The head of the rib articulates with the:
cranial and caudal costal fovea of adjacent vertebrae
107
Spinal nerves of C1 exit through the _____________ rather than the intervertebral foramen.
lateral vertebral foramen
108
How many lumbar vertebrae do cattle have?
6
109
How many sacral vertebrae do cattle and horses have?
5
110
Cattle typically have ____-____ coccygeal vertebrae.
18-20
111
How many thoracic vertebrae do horses have?
18
112
Horses typically have __-___ lumbar vertebrae.
5-7
113
Horses typically have __-__ coccygeal vertebrae.
15-21
114
What is the minimum number of cervical vertebrae in birds?
8
