Osteology of the vertebrae Flashcards
How many vertebrae are there? How many are separate? How many are fused?
33; 24 separate, 9 fused to give two structures
What are the four general functions of the vertebral column?
Protection (encloses spinal cord), support (carries weight of body above pelvis), axis (centre of gravity), movement (including posture)
What is the vertebral body?
Anterior part of vertebrae, the weight bearing component
How does the size of the vertebral body change down the vertebrae?
Gets larger; bearing an increasing amount of weight each time
What are the superior and inferior aspects of the vertebral body lined with? What separates adjacent vertebral bodies?
Hyaline cartilage; vertebral bodies are separated by a fibrocartilaginous intervertebral disc
What part of the vertebrae is made up of the vertebral arch? What does it form with the vertebral body?
Lateral and posterior parts; forms an enclosed hole, called the vertebral foramen
What do the vertebral foramina form when lined up?
The vertebral canal, which encloses the spinal cord
With their dense bony structure, what is a clinical use of imaging of the vertebral bodies?
Diagnosis of osteoporosis
What do the pedicles of the vertebral arch join to? (other bony prominences)
Anteriorly joined with vertebral body, laterally joined with transverse processes, posteriorly with the articular processes
What is the name of the bony prominence between the pedicles and spinous process?
The lamina
In which direction do the transverse processes extend away from the pedicles?
Laterally and posteriorly
What occurs at the junction between the lamina and pedicles?
Superior and inferior articular process arise; they articulate with other vertebrae, above and below
In which direction does the spinous process point?
Posterior, inferior
What are the two general functions of the intervertebral discs?
Permit flexibility (supporting curvature of spine) and act as a shock absorber
What is the general structure of an intervertebral disc?
Two regions; the jelly like nucleus pulposus, surrounded by the tough, collagenous annulus fibrosis
What is the embryonic origin of the nucleus pulposus?
The notochord
<p>
| What happens in herniation of the IV disc?</p>
<p>
The nucleus pulposus ruptures, breaking through the annulus fibrosus; this occurs in a posterior and lateral direction, putting pressure on the spinal cord which can manifest clinically in a variety of neurological and muscular symptoms</p>
How many are there of each type of vertebrae?
7 cervical, 12 thoracic, 5 lumbar, 5 fused into the sacrum, and 4 fused into the coccyx
What are the three main distinguishing features of the cervical vertebrae?
Spinous process bifurcates into two (bifid spinous process), foramen in each transverse process (foramen transverisium), and triangular vertebral foramen
What are the names of cervical vertebrae 1 and 2
The atlas and axis
Which cervical vertebra does not bifurcate, and is very long?
C7
What are found on the sides of the ventral bodies of the thoracic vertebrae?
Two demi facets on each side, for articulation with the head of its respective rib and the rib inferior to it
What is found on the transverse process of thoracic vertebrae?
Costal facet for articulation with respective rib
Describe the spinous processes of thoracic vertebrae
Slanted inferiorly and anteriorly, providing increased protection to spinal cord
Which vertebrae are the largest?
Lumbar
Describe the vertebral body of lumbar vertebrae
Large, kidney shaped; support weight of upper body
What is the only particularly distinctive feature of the lumbar vertebrae?
They have a triangular vertebral foramen
What is the shape of the sacrum? What is found on the lateral walls?
Upside down triangle, apex pointing inferiorly; on the lateral walls are facets, for articulation with the pelvis at sacro-iliac joints
How can the coccyx be recognised from the sacrum?
Lack of vertebral arches; hence no vertebral canal; the coccyx does not transmit the spinal cord
What are the names of the two joints formed by the atlas (C1)?
Articulates with the skull above to form the atlanto-occipital joint, and the axis below to form the atlanto-axial joint
Which significant features does the atlas lack?
A body or spinous process
Which cervical vertebrae is the widest?
The atlas
What is formed by the fusion of the atlas with the axial body?
The dens, or odontoid process
What are the three main features of the axis?
The dens (or odontoid process), a rugged lateral mass, and a large spinous process
What fractures and dislocates to give hangman’s fracture?
The axis pedicles
What is the function of the dens?
Prevents horizontal displacement of the axis
What are the articular surfaces of vertebral joints covered in, and connected by?
Covered in hyaline cartilage, connected by fibrocartilaginous IV disk
Which ligaments strengthen the vertebral joints?
Anterior and posterior longitudinal ligaments
What are the functions of the longitudinal ligaments of the vertebral column?
Anterior is thick and prevents hyperextension, posterior is weaker and prevents hyperflexion
What are the joints between articular processes known as? What movement do they allow?
Facet joints; allow some gliding movement
What are the four important ligaments of the facet joints?
Ligamentum flava, infraspinous, suprapsinous, intertransverse ligaments
Where does the ligamentum flava extend between?
From lamina to lamina
What are the normal curvatures of the vertebral column?
2 primary; thoracic and sacral (project out of back)
2 secondary; cervical and lumbar (project in)
What is kyphosis?
Excessive thoracic (primary) curvature, causing a hunchback deformity
What is lordosis?
Excessive (secondary) lumbar curvature, causing a swayback deformity
What is scoliosis?
A lateral curvature of the spine, usually of unknown cause
What is cervical spondylosis?
Decrease in size of the intervertebral foramina, usually due to degeneration of the joints of the spine; the smaller size of the intervertebral foramina puts pressure on the exiting nerves, causing pain
What are the causes of kyphosis?
Erosion of the anterior part of one or more vertebrae
What are causes of scoliosis?
Asymmetric weakness of the intrinsic back muscles, failure of half a vertebra to develop and a difference in length of the lower limbs
What causes lordosis?
May be associated with weakened trunk musculature. In pregnancy, women develop a temporary lordosis to compensate for alterations to their line of gravity
What anatomical abnormalities occur in the vertebral column in spina bifida?
Laminae of the lower lumbar and upper sacral vertebrae fail to develop normally and fuse; in extreme situations, the spinal nerves or even spinal cord protrude(s) backward out of the defect
Which areas of the vertebrae have the freest movement? Which have minimal movement
Cervical and lumbar regions (large IV discs, except at neck); the thoracic have minimal movement (smaller IV discs, rib articulations)
What movements are possible in the vertebrae?
Flexion, extension, lateral flexion and rotation
Why are cervical vertebrae more prone to whiplash?
The ligaments connecting them are short and thin, for mobility; during whiplash they can be torn, causing dislocation
