Lecture 7: The Spine: Fundamentals of the Body's Axis Flashcards
spinal column / vertebral column
the term for when the vertebrae are stacked, most with intervertebral discs between them and with a series of ligaments that connects
adjacent vertebrae … the skeletal foundation of the torso and axis of the major body movements of the trunk … the limbs extend off of it … it is a major supportive element for posture, whether sitting or standing … control by so-called “true back muscles” … has a segmental nature with a repeating stacked series of 24 vertebrae, along with the sacrum and coccyx linked together by articulations … has five main regions: cervical vertebrae, thoracic vertebrae, lumbar vertebrae, the sacrum, and the coccyx.
axial skeleton
consists of the skull, the hyoid bone, the vertebrae, the ribs, and the sternum
cervical vertebrae
series of seven vertebrae in the neck … referred to as C1, C2, C3, C4, C5, C6, and C7 … the smallest type of vertebrae with a more petite vertebral body and concave superior surface … typically have two prongs to their spinous processes (a bifid spinous process) … unlike other vertebrae, have transverse foramina within their transverse processes to transmit the vertebral artery … one of three regions of the vertebral column
the atlas (vertebrae)
C1 … helps hold up the skull … the only
vertebra without a vertebral body, instead it consists of a neural arch with a pair of transverse foramina on its lateral aspects … two cup-shaped superior articular facets join with a pair of matching convex facets at the base of the skull to form one of the ellipsoidal or condyloid joints
the axis (vertebrae)
C2 … like other cervical vertebra but with a dens or odontoid process (a projection on the superior surface of its body) … the superior articular facets are flat, as are the matching inferior articular facets of C1 … the dens forms
an axis of rotation where it sits in the anterior aspect of the neural arch of C1 … the transverse ligament on the atlas makes a sling around its dens to hold it in place
thoracic vertebrae
series of 12 vertebrae in the rib cage … referred to as T1, T2, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12 … each has several articulation sites for a pair of ribs (most people have a total of 24 ribs) … go from a relatively small size following the cervical spine to a relatively large size as they approach the lumbar region … one of three regions of the vertebral column
lumbar vertebrae
series of five spinal elements in the low back … referred to as L1, L2, L3, L4, L5 … have large and boxy bodies and smaller transverse processes but larger spinous processes … the superior and inferior articular
processes are also larger … lack transverse foramina and articulation sites for ribs … one of three regions of the vertebral column
the sacrum
the vertebrae below the lumbar vertebrae … usually formed from five sacral vertebrae that unite during development usually during puberty into a single triangular bone … has a body that is topped by an intervertebral disc that forms a cartilaginous amphiarthrotic
joint with the inferior surface of the body of the fifth lumbar vertebra, L5 … has a set of superior articular facets (like other vertebrae) that join with the inferior articular facets of L5 … has lateral masses that reach out toward joint surfaces that link the sacrum with the two pelvic bones (as opposed to transverse processes) … has a median sacral crest running (as opposed to spinous processes) down its posterior surface … (as opposed to vertebral foramen) has a canal down its midline that connects to openings used by ventral and dorsal rami on both its front and back of the sacrum. The sacral canal terminates in the sacral hiatus
anterior sacral foramina
a canal down the sacrum’s midline that connects to openings on its front
posterior sacral foramina
a canal down the sacrum’s midline that connects to openings on its back
sacral hiatus
the opening where the sacral canal terminates … can be palpated on the surface
sacral promontory
a forward projection on the superior and anterior aspect of the sacrum
coccyx
the small tailbone that articulates with the sacrum … fused from three or four small elements
There isn’t a disc between the skull and the atlas, nor between the atlas and axis, and there are only remnants of discs within the sacrum. Moreover, since the discs increase in size from the cervical spine to the lumbar spine, together they make up about 20% to 25% of the length of a person’s spine.
… one of five regions of the vertebral column
vertebral body
a central region in nearly all vertebrae
neural arch
connected to the vertebral body and composed of two main parts: a pair of pedicles and a pair of laminae … surrounds a vertebral foramen …
above each pedicle is a superior articular process, and below each pedicle is an inferior articular process
pedicles
stalk-like extensions that attach the neural arch to the vertebral body
laminae
part of the neural arch that each other
superior articular process
an articulation
inferior articular process
an articulation
transverse process
an articulation located laterally off the neural arch in a pair … go in a transverse orientation … serves as attachment sites for ligaments and muscles.
spinous process
an articulation that extends off of the posterior aspect of the laminae… serves as attachment sites for ligaments and muscles
vertebrae numbering
starts at the top of each section and proceeds inferiorly: C1-C7, T1-T12, L1-L5, sacrum, coccyx
lordotic curve
forward (“anterior”) curvature of the spine … the curves in cervical and lumbar spine
kyphotic curve
backward (“posterior”) curvature of the spine… the curves in the thoracic and sacral spine
cervical curve
lordotic curve from C2-T2
thoracic curve
kyphotic curve from T2-T12
lumbar curve
lordotic curve from T12-sacrovertebral angle
sacral and coccygeal curve
kyphotic curve formed by the sacrum and coccyx
intervertebral disc
lies between adjacent vertebrae in the vertebral column … allows slight movement of the vertebrae … acts as a ligament to hold the vertebrae together … functions as a shock absorber for the spine … make up about 20% to 25% of the length of a person’s spine … there is not a disc between the skull and the atlas, nor between the atlas and axis, and there are only remnants of discs within the sacrum
cartilaginous joints
formed by the intervertebral discs … one of two types of joints that link most vertebrae to their adjacent vertebrae
synovial joints
between the inferior articular facets of one vertebra and the superior articular facets of the vertebra below it … one of two types of joints that link most vertebrae to their adjacent vertebrae
fibrocartilage
a type of cartilage dense with collagen fibers
annulus fibrosus
the outer ring of intervertebral discs … made of fibrocartilage … surrounds a gel-like central region called the nucleus pulposus … links the adjacent vertebral bodies together
nucleus pulposus
the inner gel-like central region of intervertebral discs … acts like an inner shock absorber to help withstand compression due to weight placed on the spine … surrounded by annulus fibrosus
herniated disc
when the nucleus pulposus pushes through a tear in that outer ring of fibrocartilage if forces become too great, especially if the annulus fibrosus is dried out and brittle
intervertebral foramen
the space formed between the bones by the notches at the pedicles of adjacent vertebrae when they are stacked
vertebral foramina
extend down the spinal column, forming a spinal cavity through which the spinal cord passes
anterior longitudinal ligament
a wide and strong ligament that runs down the length of the stacked bodies of the vertebrae on their anterior side … helps reinforce the cartilaginous joints formed by the intervertebral discs and attach to the discs as well as the vertebrae they join
posterior longitudinal ligament
a narrow ligament that runs down the posterior aspect of the stacked vertebral bodies … helps reinforce the cartilaginous joints formed by the intervertebral discs and attach to the discs as well as the vertebrae they join
