Axial Skeleton- Vertebral Column Flashcards
1
Q
What is the vertebral column?
A
- Composed of 26 bones, including 24 individual vertebrae and the fused vertebrae that form both the sacrum and the coccyx
- Provides vertical support for the body
- Supports the weight of the head
- Helps maintain upright body position
- Helps transfer axial skeletal weight to the appendicular skeleton of the lower limbs
- Houses and protects the delicate spinal cord
- Provides a passageway for spinal nerves that connect to the spinal cord
- Partitioned into 5 regions
2
Q
What are vertebrae?
A
- Individual bones that are identified by a capital letter that denotes their region, followed by a numerical subscript that indicates their sequence (going from superior to inferior)
- Smallest near the skull and become gradually bigger moving inferiorly through the body trunk as weight bearing increases
3
Q
What are cervical vertebrae?
A
- There are 7
- Form the bones of the neck
- First cervical vertebrae (C1) articulates superiorly with the occipital condyles of the occipital bone of the skull
- The seventh cervical vertebra (C7) articulates inferiorly with the first thoracic vertebra
- Large foramen
4
Q
What are thoracic vertebrae?
A
- There are 12
- Form the superior regions of the back and each articulates laterally with one or two pairs of ribs
- The 12th thoracic vertebra (T12) articulates inferiorly with the first lumbar vertebrae
- Lack transverse foramina and bifid spinous processes of the cervical vertebrae
- Have a heart-shaped body that is bigger than those of the cervical vertebra
- Spinous processes tend to angle sharply in an inferior direction
5
Q
What are lumbar vertebrae?
A
- There are 5
- Form the inferior concave region (“small”) of the back
- The 5th lumbar vertebra (L5) articulates inferiorly with the sacrum
- Largest of all vertebrae, since they bear most of the body’s weight
- Have neither transverse foramina or costal facets
- Thin transverse processes that point dorsolaterally
6
Q
What is the sacrum?
A
- Formed from 5 sacral vertebrae, which fuse into a single bony structure by the mid to late 20’s
- Articulates with L5 superiorly and with the first coccygeal vertebra inferiorly
- The sacrum also articulates laterally with the 2 ossa coxae (hip bones)
- Forms the posterior wall of the pelvic cavity
7
Q
What is the coccyx?
A
- Commonly called the “tailbone”
- Formed by 4 coccygeal vertebrae that start to unite during puberty
- The first coccygeal vertebra (Co1) articulates with the inferior end of the sacrum
- When much older the coccyx may also fuse to the sacrum
- Attachment site for several ligaments and some muscles
- The prominent laminae of the first coccygeal vertebrae are known as the coccygeal cornea
8
Q
What are spinal curvatures?
A
- The vertebral column has some flexibility, so when viewed laterally, the adult vertebral column has 4 curves
- Cervical, thoracic, lumbar and sacral curvatures
- They better support the weight of the body when standing
9
Q
What are the primary spinal curves?
A
- The thoracic and sacral curvatures
- Appear in late fetal development
- Also called accommodation curves because they accommodate the thoracic and abdominopelvic viscera
10
Q
What are the secondary spinal curves?
A
- The cervical and lumbar curvatures
- Appear after birth (3-4 months of age)
- These curves arc anteriorly and are also known as compensation curves because they help shift the trunk weight over the legs
- The lumbar curvature appears by the first year of life (learning to stand and walk)
11
Q
What is the vertebral body?
A
- Cylindrical, anterior region of each vertebra
- Also called a centrum
- The weight-bearing structure of almost all vertebra
12
Q
What is the vertebral arch?
A
- Posterior to the vertebral body
- Also known as neural arch
- Together the vertebral body and arch enclose a roughly circular opening called the vertebral foramen
- Composed of 2 pedicles and 2 laminae
13
Q
What is the vertebral canal?
A
- Collectively all the stacked vertebral foramina form a superior-to-inferior directed canal that contains the spinal cord
14
Q
What are intervertebral foramina?
A
- Lateral openings between adjacent vertebrae
- Provide a horizontally directed passageway through which spinal nerves travel to other parts of the body
15
Q
What are vertebral pedicles?
A
- Originate from the posterolateral margins of the body (foot)
- 2 parts make up a section of the vertebral arch
16
Q
What are vertebral laminae?
A
- Extend posteromedially from the posterior edge of each pedicle
- 2 parts make up a section of the vertebral arch
17
Q
What are spinous processes?
A
- Project posteriorly from the left and right laminae (middle of the arch)
- Most can be palpated through the skin of the back
18
Q
What are transverse processes?
A
- Lateral projections on both sides of the vertebral arch
19
Q
What are articular processes?
A
- On both the superior and inferior surfaces of each vertebra
- Project from the junction between the pedicles and laminae
- The inferior articular processes of each vertebrae articulate with the superior articular processes of the vertebra immediately inferior to it
- Each have a smooth surface called an articular facet (angles of these differ)
20
Q
What are intervertebral discs?
A
- Pads of fibrocartilage that separate adjacent vertebral bodies
- Make up about one quarter of the entire vertebral column
- Act as shock absorbers and allow the vertebral column to bend (can withstand a certain amount of compression)
- Composed of an outer ring of fibrocartilage called the annulus fibrosus
- And an inner circular region called the nucleus pulposus
21
Q
What are transverse foramina? (cervical vertebrae)
A
- The transverse processes of the first 6 cervical vertebrae are unique in that they contain prominent round foramen
- Provide a protective bony passageway for the vertebral arteries and veins supplying the brain
22
Q
What is the atlas? (cervical vertebrae)
A
- The first cervical vertebra (C1)
- Supports the head via its articulation with the occipital condyles of the occipital bone
- It’s recognizable from other vertebrae because it lacks a body and a spinous process
- Has lateral masses that are connected by semicircular anterior and posterior arches
- Each arch containing anterior and posterior tubercles
- Atlas has depressed oval superior articular facets that articulate with the occipital condyles
23
Q
What is the axis? (cervical vertebrae)
A
- During development, the body of the atlas fuses to the body of the second cervical vertebra (C2)
- This fusion produces the dens
24
Q
What is the dens? (cervical vertebrae)
A
- The most distinctive feature of the axis
- Rests in the articular facet for dens of the atlas, where it is held in place by a transverse ligament
- Acts as a pivot for the rotation of both the atlas and the skull
- Because both the dens and the spinal cord occupy the vertebral foramen at the level of the axis, any trauma that dislocates the dens often results in serious injury
25
Q
What is the atlanto-occipital joint? (cervical vertebrae)
A
- The articulation between the occipital condyles and the atlas
- Permits us to nod our head “yes”
26
Q
What is the atlantoaxial joint? (cervical vertebrae)
A
- The articulation between the atlas and the axis
- Permits us to shake our heads “no”
27
Q
What is the vertebra prominens? (cervical vertebrae)
A
- The seventh cervical vertebra (C7)
- Represents a transition to the thoracic vertebral region and has some features of thoracic vertebrae
- Has a large spinous process which can be easily felt through the skin (slight protrusion between the shoulder blades and inferior to neck
28
Q
What are costal facets/ demifacets? (thoracic vertebrae)
A
- On the lateral side of the body and on the sides of the transverse processes
- Costal facets: circular depression that articulates with the entire head of the rib
- Costal demifacets: semicircular depression that articulates with either the superior or inferior edge of the head of the rib
29
Q
Vertebra T1-T10 have… (facet variations/thoracic vertebrae)
A
- Transverse costal facets on their transverse processes
30
Q
Vertebrae T11-T12 lack… (facet variations/thoracic vertebrae)
A
- Transverse costal facets, because the 11th and 12th ribs do not have tubercles
31
Q
What are the variations found in the bodies of the thoracic vertebrae?
A
- Body of T1 bears a full costal facet for the first rib and a demifacet for the second rib
- The bodies of the vertebrae T2-T8 have 2 demifacets each
- The body of the vertebrae T10-T12 have a single whole facet to articulate with the respective ribs
32
Q
What is the apex of the sacrum?
A
- A narrow, pointed portion of the bone that projects inferiorly
33
Q
What is the sacral canal?
A
- The vertebral canal of the sacrum that becomes much narrower
- Terminates in an inferior opening called the sacral hiatus (represents where the laminae of the last sacral vertebrae failed to fuse)
34
Q
What is the promontory? (sacrum)
A
- The anterosuperior edge of the first sacral vertebrae which bulges anteriorly into the pelvic cavity
35
Q
What are sacral foramina? (sacrum)
A
- Paired anterior sacral foramina permit the passage of nerves to the pelvic organs
- On the dorsal side of the sacrum there are paired posterior sacral foramina that are openings for spinal nerves
36
Q
What is the auricular surface? (sacrum)
A
- On the lateral surface of the sacrum wings (ala)
- Marks the site of articulation with the os coxae of the pelvic girdle forming the sacroiliac joint
