A2 - protection of the CNS 3 Flashcards
how many spinal nerves does the vertebral column have?
31 pairs
how is the vertebral column divided?
cervical - 7
thoracic - 12
lumbar - 5
sacral - 5
coccygeal - 4 (fused)
what forms the vertebral arch?
the pedicals and laminae
functions of the vertebral column
- supports the body’s frame and connects the head to the rest of the body
- serves as protection for the spinal cord
- involved in posture and locomotion
- supports the weight of the body above the pelvis
describe the curvatures of the vertebral column
cervical
thoracic — primary
lumbar
sacral — primary
functions of vertebral curvatures
increase the strength of the vertebral column, its flexibility and its ability to absorb shock
what is a primary curvature?
concave anteriorly — thoracic and sacral
what are 3 abnormal curvatures?
- KYPHOSIS = an exaggerated thoracic curve. may result from osteoporosis
- LORDOSIS = an exaggerated lumbar curve. often seen in obesity and pregnancy
- SCOLIOSIS = an exaggerated lateral curve. most often seen in girls and may be associated with a. growth spurt
identify the parts of a typical vertebra
A = spinous process
B = lamina
C = vertebral foramen
D = transverse process
E = body
F = superior articular facet
G = pedicle
what are intervertebral discs?
- fibrocartilage pads that are sandwiched between adjacent vertebral bodies
- responsible for 25% the length of the vertebral column
where are iv discs not found?
C1-C2 and after S2
what are A and B?
A = nucleus pulposis — forms a gelatinous mass that is compromised of water, a few collagen fibres and some cartilage cells
B = annulus fibrosis — made of many sheets of fibrous connective tissues that are layered in rings around the nucleus pulposis
what are 3 functions of iv discs?
- increase size of vertebral column
- act as shock absorbers
- permit movement
describe cervical vertebrae and their distinct features
- 7
- have the smallest and thinnest intervertebral discs
- the most mobile
- have distinct features like : transverse foramina, 2 tubercles (anterior and posterior) and split (bifid) spinous processes, large, triangular vertebral foramen, small body
which cervical vertebrae are typical?
C3-C6
what do the transverse processes of cervical vertebrae end laterally in?
an anterior tubercle and a posterior tubercle — provide attachment for levator scapulae and scalenes
what is between the tubercles on the transverse processes of cervical vertebrae?
grooves for spinal nerves
describe the atlas (C1)
- consists of 2 arches (anterior and posterior) and contains 2 lateral masses
- has neither a body nor a spinous process
- the masses articulate with the occipital condyles of the skull, supporting its weight
- has a groove for the vertebral artery
describe the axis (C2)
- has an upward tooth-like projection (dens or odontoid process) and 2 superior articular facets
- it encircles both the dens and the spinal cord inside its coverings (meninges)
- it lies anterior to the spinal cord and serves as the pivot about which head rotation occurs
what does the dens of the axis articulate with?
the anterior arch of the atlas
what holds the dens in place against the anterior arch of the atlas?
the transverse ligament of the atlas
what cervical vertebra has the longest spinous process?
C7 = vertebra prominens
how is C7 atypical?
only transmit small accessory veins — thus the transverse foramina are smaller, and occasionally they are absent
what passes through the transverse foramina of the cervical vertebrae?
the vertebral arteries and their accompanying veins
describe thoracic vertebrae and their distinct features
- 12
- play a role in forming the thoracic cage
- contain several distinct features:
- costal facets — articulate with ribs
- heart-shaped vertebral bodies
- smaller vertebral foramina
- long and strong spinous and transverse processes which
point inferiorly
which thoracic vertebrae are typical?
T5-T8
demi facets vs costal facets
demi-facets : on the sides of each vertebral body. these articulate with the heads of the ribs
costal facets : on transverse processes. these articulate with the tubercles of ribs. only present on T1-T10
what do atypical thoracic vertebrae bear? explain
= whole costal facets instead of demifacets
> the superior costal facets of T1 aren’t demifacets because there are no demifacets on the C7 vertebra above and rib 1 articulates with only T1
T1 has a typical inferior costal (demi) facet
T10 has only one bilateral pair of whole costal facets located partly on its body and partly on its pedicle
T11 and T12 also have only a single pair of whole costal facets, located on their pedicles
there is no articulation between T11 and T12 with their ribs
what are the distinct lumbar vertebrae features?
- large, kidney shaped body
- quadrangular spinous processes
- triangular vertebral foramen
- long, slender transverse processes
- larger grey matter
why are lumbar vertebrae the largest in the body?
facilitate weight-bearing
what are the laminae and pedicels like in lumbar vertebrae/
thick and strong
what are the lumbar spinous processes like?
short and sturdy for the attachment of strong lumbar muscles
what is the largest vertebrae of the entire body and what does it do?
L5
- supports and transmits body weight to the base of the sacrum
where does the spinal cord terminate?
conus medullaris — L1/L2
describe the sacrum
- 5
- fused
- main role is to transmit the entire wight of the upper body to the pelvis in order to reach the lower limbs
- has a base, apex, and 3 surfaces (pelvic, posterior and lateral)
- sacral canal in middle = continuation of spinal canal
what does the sacral canal contain?
cauda equina of spinal cord
what do sacral foramina do?
allow for the exit of the spinal nerves
what are sacral crests (median, intermediate, lateral)?
represent the fused processes of the sacral vertebra
describe the coccyx
- 4
- 2 surfaces: pelvic and posterior
- short transverse processes
- point of attachment for the gluteus maximus and coccygeal muscles
why does the ability of iv discs to absorb shock decrease as a person ages and why are they more likely to tear?
the nucleus pulposus begins to dehydrate and the concentration of proteoglycans in the matrix decreases, and the annulus becomes weaker
what is a prolapsed disc?
when the nucleus pulposus is forced out of the disc
what are the iv symphases (discs)?
secondary cartilaginous (symphyses)
what are cervical vertebrae also connected by?
uncovertebral joints (clefts of Luschka)
what are the vertebral bodies and iv discs reinforced by?
2 fibrous, longitudinal ligaments = anterior and posterior longitudinal ligaments
describe the anterior longitudinal ligament
- extends along the anterior surface of the bodies of the vertebrae, from skull to sacrum
- runs entire length of vertebral column
- thicker and stronger than posterior
what are the functions of the anterior longitudinal ligament?
- maintains stability of the joints
- prevents hyperextending of the vertebral column
describe the posterior longitudinal ligament
- runs along the anterior aspect of the vertebral canal from skull to sacrum
- it is attached to the posterior borders of the IV discs
- it is narrow where is overlies each body, and widens out to cover the back of each disc
- helps in a small way to limit flexion of the vertebral column
what do the anterior and posterior longitudinal ligaments look like?
what are adjacent vertebral arches connected by?
synovial joints called zygapophyseal (facet) joints
describe the zygapophyseal (facet) joints
- only synovial joints of the spine
- formed between superior and inferior articular facets
- facilitate flexion and extension in the cervical and thoracic spines
- also permit rotational movements in the thoracic spine