Back & Vertebral Column - Osteology Flashcards
how many vertebrae in each of the 5 regions of the vertebral column?
cervical - 7
thoracic - 12
lumbar - 5
sacral - 5 fused vertebrae
coccygeal - 4 fused vertebrae
how is the vertebral column involved in protecting the spinal cord & spinal nerves?
vertebrae encircle the spinal nerve - create the spinal canal for protection
vertebrae also articulate to form intervertebral foramina - allows spinal nerves to exit and pass through vertebral column protected
what structures does the vertebral column protect?
spinal cord
spinal nerves
posterior protection for neck, thorax, abdomen, and pelvis
what role does the vertebral column play in supporting the body?
serves as a rigid support structure and allows the trunk to remain upright - supports the head & maintains posture
how does the vertebral column enable movement?
small movements at intervertebral joints add up along the vertebral column - overall allows significant movement and flexibility
variations in movements depend on the spinal region
what are the key muscle attachments to the vertebral column?
muscles controlling spinal movement
upper and lower limb muscles
some neck muscles - e.g. scalene muscle
what is the importance of the vertebrae and pelvis in haematopoiesis?
they are major sites of blood cell production postnatally
list the functions of the vertebral column (5)
protection of the spinal cord, spinal nerves & posterior regions
supportive structure - keeps trunk upright and supports the head
allows movement & flexibility - small movements allowed at intervertebral joints overall allow significant movements like flexion, extension & rotation throughout the VC
key site for muscle attachments - e.g. upper and lower limb muscles, scalene muscle of the neck
major site of haematopoiesis
how many curvatures are present in the adult spine?
4
main functions of the spinal curvatures?
- distributing mechanical stress during movement
- providing flexibility
- adding shock-absorbing resilience
how do the spinal curvatures accommodate activities like carrying heavy loads?
spinal curvatures deepen to accommodate carrying heavy loads - return to their original shape once the load is removed
what are the two types of spinal curvatures, and how do they differ?
primary curvatures - retained from the foetal C-shaped curvature and are concave anteriorly
secondary curvatures - develop after birth as a child grows, and are concave posteriorly
which curvatures of the spine are considered primary curvatures?
thoracic and sacrococcygeal kyphosis/ curvatures
which curvatures of the spine are considered secondary curvatures?
cervical and lumbar lordosis/ curvatures
what is cervical lordosis? when does it develop?
cervical lordosis - secondary curvature of the cervical spine
develops as an infant begins sitting up & lifting their head to strengthen support for the head
what is lumbar lordosis? when does it develop?
lumbar lordosis - secondary curvature of the cervical spine
develops as a child starts standing and walking - helps support the upper body & balance
function of the vertebral body? how does it change going down the vertebral column?
function: weight-bearing from above & connects intervertebral discs above and below as a support structure
increases in size from the cervical to lumbar region = accommodates increasing load of the body moving down the VC
two components of the vertebral arch?
pedicle
lamina
what is the pedicle?
component of the vertebral arch - connects the vertebral body to the transverse and articular processes
what are the lamina?
flat plates of bone that extend from the transverse processes and join at the midline to form the spinous process
what is the name of the joint between the superior and inferior articular processes of vertebrae?
zygapophyseal joints
what is the vertebral foramen? function?
large central hole formed by the vertebral arch
function: allows the spinal cord to pass through
what do the foramina of all vertebrae form? what is the significance?
vertebral/ spinal canal - where spinal cord passes down
compare the vertebral bodies of cervical, thoracic and lumbar vertebrae
cervical: small and oval-shaped with curved end plates
thoracic: heart-shaped and medium-sized with flat endplates
lumbar: large and kidney-shaped with flat end plates
compare the vertebral foramina of cervical, thoracic and lumbar vertebrae
cervical: triangular and large
thoracic: round and smaller (spinal cord narrows here)
lumbar: triangular and large
why is the cervical vertebral foramina triangular and large?
allows for cervical enlargement of the spinal cord to pass through - where UL nerves arise
which regional vertebrae have transverse foramen? what function do they serve?
cervical vertebrae
function: allow passage for the vertebral arteries and veins that ascend toward the skull
what is unique about the spinous & transverse processes of cervical vertebrae?
spinous & transverse processes are bifid
transverse processes have anterior & posterior tubercles - serve as attachment points for muscles
compare the spinous processes of cervical, thoracic and lumbar vertebrae
cervical: bifid from C2-6
thoracic: long and project downwards, overlap with adjacent vertebrae
lumbar: short & square, project almost directly posteriorly
compare the orientations of the superior articular facets of cervical, thoracic and lumbar vertebrae
cervical: 45 degrees superoposteriorly
thoracic: 60-70 degrees posteriorly
lumbar: 90 degree posteromedially
orientation of the superior articular facets of cervical vertebrae?
45 degrees superoposteriorly
orientation of the superior articular facets of thoracic vertebrae?
60-70 degrees posteriorly
orientation of the superior articular facets of lumbar vertebrae? what movement does this limit?
90 degrees posteromedially - limits rotation
function of the superior articular vertebral facets?
articulates with the (inferior facet of the) vertebra above
articulations that form the costotransverse joint?
transverse costal facet (on transverse processes) of thoracic vertebrae articulates with the tubercle of the rib
- e.g. T5 vertebrae transverse costal facet articulates with tubercle of 5th rib
articulations that form the costovertebral joint (superior & inferior)?
demifacets (superior & inferior) of thoracic vertebrae articulate with the head of ribs
superior demifacet articulates with the lower part of the head of the rib
inferior demifacet of the vertebrae above articulates with the upper part of the same rib
e.g. rib 6 articulates with inf demifacet of T5 & sup demifacet of T6
what thoracic vertebrae have full facets? what does this mean in terms of articulations?
T1, 10, 11, 12 have full facets
full facets articulate with the whole head of the first rib - e.g. full facet of T1 articulates with head of 1st rib
what is missing from the atlas (C1) that typical vertebrae have? what structures replace these missing parts?
vertebral body & spinous process are missing
replaced by an anterior tubercle on the anterior arch (instead of a vertebral body) and a posterior tubercle on the posterior arch (instead of a spinous process)
function of the lateral masses on the atlas (C1)?
absorb and distribute load from the skull to the axis (C2) vertebra below
articulations forming the atlanto-occipital joint?
superior articular surfaces of the atlas and the occipital condyles of the occipital bone
what type of joint is the atlanto-occipital joint?
synovial condyloid
what movement does the atlanto-occipital joint allow for?
flexion and extension of the head - nodding/ yes movements
function of the dens (odontoid process) on the axis (C2)?
acts as a pivot point for the atlas (C1) and skull to rotate - allows for left and right head movements (no movements)
function of the transverse ligament of C1?
transverse ligament wraps around the posterior part of the dens - secures it in place, prevents posterior displacement into the vertebral canal which could damage the spinal cord
the atlantoaxial joint consists of three articulations. what are they?
medial atlantoaxial joint - between the dens of C2 and the facet for dens on the anterior arch of C1
lateral atlantoaxial joints (2) - between the superior articular facets of C2 and inferior articular facets of C1
what ligament reinforces the atlantoaxial joint?
transverse ligament of atlas
what type of the joint is the atlantoaxial joint?
synovial pivot
what joint allows for yes movements?
atlanto-occipital joint (flexion and extension)
what joint allows for rotational head (no) movements?
atlantoaxial joint
how many vertebrae compose the sacrum?
5 fused vertebrae (S1-5)
what are the transverse ridges of the sacrum/ median sacral crest?
remnants of the fusion process of the vertebral bodies - mark where the individual vertebrae used to join
what is the ala of sacrum? its function?
lateral broad extension of S1 - key in transferring upper body weight to the pelvic girdle
articulations that form the sacroiliac joint? significance of this joint?
auricular surface of the sacrum articulates with the pelvic ilium
significant for weight transfer from the upper body
what components of the sacrum are significant for weight transfer?
sacroiliac joint
ala of the sacrum
what is the anterior sacral foramina & its function?
anterior sacral foramina = 4 openings on the anterior surface of the sacrum
allows for the passage of the anterior rami of spinal nerves
what is the posterior sacral foramina & its function?
posterior sacral foramina = 4 openings on the posterior surface
allows for the exit of the posterior (dorsal) rami of the sacral nerves (smaller than the anterior rami)
articulations forming the lumbosacral joint?
superior articular facets of the sacrum with inferior articular facets of L5
why is the coccyx a rudimentary structure? how is it still functionally important?
rudimentary as its an evolutionary remnant of a tail
functionally important - still serves as an important attachment site for muscles and ligaments
how many vertebrae form the coccyx?
typically 4 fused coccygeal vertebrae - can vary between 3-5
function of the coccygeal horns/ cornua?
articulate with the sacral horns above to form a small joint between the sacrum and coccyx
the spinal canal ends at the lower end of the sacrum. describe the pathway of the coccygeal nerve?
coccygeal nerve passes posterior to the coccyx and then laterally below Co1
what runs through the vertebral foramen?
spinal cord
which cervical vertebrae don’t have bifid spinous processes?
C1, C7
what is the C7 vertebrae commonly called due to its long spinous process?
vertebra prominens
what type of vertebrae has transverse foramen? what structures pass through this foramina?
cervical vertebrae have transverse foramina - vertebral arteries & veins pass through
what primary movement occurs between the dens and the anterior arc of atlas?
rotation of the head and neck
fracture of C2 is often referred to as “a hangman’s fracture”. which spinal nerve is likely to be damaged? what effect will this have?
C3 spinal nerve - will impair diaphragm function, respiration would stop
what is the name of the joint between the head of ribs and vertebral body?
costovertebral joint (demi facet/ full facet & head of ribs)
what is the name of the joint between the tubercle of ribs and vertebral body?
costotransverse joint
what is the continuation of the vertebral canal called in the sacrum?
sacral canal
at what joint does the sacrum articulate with the pelvis?
sacroiliac joint
what is the role of the sacral foramina?
exit points for the sacral nerves
course of the anterior rami nerve roots from the sacral canal
nerve roots of sacral spine descent through sacral canal –> emerge through anterior sacral foramina as anterior rami –> unite to form the sciatic nerve
name given to the inferior termination of the spinal cord?
conus medullaris
