Lec 2 Reading Questions Flashcards
what is the basic anatomy of any vertebra
typical vertebra have a vertebral body and a vertebral arch. the vertebral body is made up on lateral sides by two pedicles, which come together by two lamina. At the point where the lamina join, a spinous process extends posteriorly (and generally inferiorly) from the roof of the vertebral arch. The “roof” of the vertebral arch is where the lamina meet in midline!
On each side of the vertebral arch, a transverse process extends laterally from where the lamina and pedicles meet. In this same area an inferior and a superior articular process extend respectively, and articulate with the respective process of the adjavent vertebrae.
what are the curves of the vertebral column?
primary and secondary.
- cervical is secondary, thoracic is primary, lumbar is secondary, and sacral/coccygeal is primary.
- brings center of gravity to a line, and expends the least amount of muscle energy to maintain upright. lumbar region/ lower back pain is common.
what makes up the vertebral canal and what goes inside?
extends from CI to SV
anterior wall is formed by the vertebral bodies, intervertebral discs, and associated ligaments, including posterior longitudinal ligament
the lateral walls and roof are formed by the vertebral arches and ligaments
-inside the canal is the spinal cord which is surrounded by three connective tissue membranes : pia (innermost, intimate with surface of spinal cord), arachnoid (separated with pia by subarachnoid space which has cerebrospinal fluid), and the dura mater which is the thickest- it likes directly against but isnt attached to the arachnoid mater.
-inside the vertebral canal the dura mater is separated from surrounding bone by an extradural (epidural) space, containing loose connective tissue, fat, and a venous plexus.
what makes up the intervertebral foramen and what goes into them?
intervertebral foramen are made by the superior articular process of inferior vertebra and inferior process of superior adjavent vertebra (zygapophysial joint connects these). The superior/inferior of the foramen are notches in adjacent pedicles, the posterior is the articular processes of the vertebral arches and the associated joint, and the anterior border is the intervertebral disc between the vertebral bodies.
-each spinal nerve exits the vertebral canal laterally through an intervertabral foramen.
what are the major differences between the cervical , thoracic, and lumbar vertebrae?
cervical: characterized by small size, a foramen in each transverse process called the foramen transversarium.
- vertebral body is short in height and square shaped when viewed from above, it also has a concave superior, and convex inferior surface.
- spinous process is short and bifid
- vertebral foramen is TRIANGULAR!
Thoracic: characterized by their articulation with ribs. typical one has two partial facets (superior and inferior costal facets) on each side of the vertebral body for articulation with the head of its own rib and the head of the rib below. Superior is much larger than the inferior one. Each transverse process also has a facet (transverse costal facet) for articulation with the tubercle of its own rib.
-vertebral body is somewhat heart shaped, vertebral foramen is CIRCULAR!
Lumbar: distinguished by the other two for being particularly large! they lack facets for articulation with ribs. Transverse processes are thin and long (except LV, which are large and cone shaped for attachment with iliolumbar ligaments to connect the transverse processes to the pelvic bones) the vertebral body of a typical lumbar is cylindrical!!! and the vertebral foramen is TRIANGULAR, and larger than in thoracic vertebrae!!!
what is the difference between the atlas vertebra and other vertebrae?
The Atlas (CI) articulates with the head. Its major distinguishing feature is that it lacks a vertebral body. There is no vertebral disc between CI and CII.
- it is ring shaped, and composed of two lateral masses interconnected by an anterior arch and a posterior arch. each lateral mass articulates with an occipital condyle of the skull abovem and below with the superior articular process of vertebra CII (the axis).
- the superior articular surfaces are bean shaped and concave (also the lateral masses), whereas the inferior ones are almost ciruclar and flat.
- posterior surface of the anterior arch has facet for the dens extending from the axis.
what is the difference between the axis vertebra and other vertebrae?
large dens which extends superior from vertebral body. anterior surface has an oval facet for articulation with the anterior arch of the atlas. two superolateral surfaces on the dens are circular for attaching alar ligaments, which connect the dens to the medial surfaces of the occipital condyles. These check excessive rotation of the head and atlas relative to the axis.
which ligaments hold the vertebra in place and where are they located?
- anterior longitudinal ligament (base of skull all the way to anterior of sacrum. along its length its attache to the vertebral bodies and intervertebral discs.
- posterior longitudinal ligament on posterior surfaces of the vertebral bodies and lines the atnerior surface of the vertebral canal. it is attached along its length to vertebral bodies and intervertebral discs also. upper part of it which connects CII to the intracranial aspect of the base of the skull is termed the tectorial membrane!
- Ligamenta flava on each side passes between laminae of adjacent vertebrae. Mostly elastic tissue and form part of the posterior surface of the vertebral canal. each one runs between the posterior surface of the lamina on the vertebra below to the anterior surface of the lamina fo the vertebra above. ligamenta flava resists separation of the laminae in flexion and assist in extension back to the anatomical position.
- supraspinous ligament connects and passes along the tips of the spinous processes from vertebra CVII to the sacrum. from CVII to the skull the ligament is called the ligamentum nuchae and is a triangular sheet like structure in median sagittal plane. (base of triangle is attached to the skull- from the external occipital protuberance to the foramen. magnum. the apex is attached to the tip of spinous process of CVII. The deep side of triangle is attached to the posterior tubercle of CI and the spinous process of the other cervical vertebrae.)
- interspinous ligaments : pass between adjacent vertebral spinous processes. they attach from the base to the apex of each spinous process and blend with the supraspinous ligament at the posterior end, and the ligamenta flava anteriorly on each side.
What are the parts of the spinal cord? what are its coverings?
It has two enlargements - cervical (C5 to T1 spinal nerves) and lumbosacral (L1 to S3 nerves). for upper and lower limbs.
- the distal end of the cord is called the conus medullaris (cone shape). A fine filament of connective tissue continues down from the apex of the conus medullaris.
- filum terminae is the end from pial part (where the filament of CT is covered in subarachnoid space still) and the dural part (after end of subarachnoid space at SII)
the external surface has fissures and sulci on spnial cord:
- the anterior medial fissue extends the length of the anterior surface - the posterior median sulcus extends along the posterior surface - the posterolateral sulcus on each side of the posterior surface marks where the posterior rootles of spinal nerves enter the cord
internally- small central canal surrounded by grey and white matter. Grey is rich in nerve cell bodies, longitudinal columns along the cord, and in cross section these form a H shaped apperance in the centrla region of the cord. the white surrounds this and s rich in nerve cell processes, large bundles of tracts which ascend and descend in the cord to other spinal cord levels or carry info to and from the brain.
how is the spinal cord supplied with blood?
Two sources:
- longitudinally oriented vessels (single anterior spinal artery, originates within cranial cavity and goes down parallel to anterior medial fissue, along spinal cord. TWO posterior spinal artiers which also start in cranial cavity right and left descent along the spinal cord bracket posterolateral sulcus and the connection of posterior roots with the spinal cord), arising superior to the cervical portion of the cord which descent on the surface of the cord; and
- feeder arteries which enter the vertebral canal through the intervertebral foramina at every level; these “Segmental spinal arteries” arise mostly from the vertebral and deep cervical arteries in the neck, the posterior intercostal arteries in the thorax, and the lumbar arteries in the abdomen. after entering by vertebral foramen the segmental spinal arteries give rise to anterior and posterior radicular arteries (every vertebral level) these follow and supply the anterior and posterior roots.
the anterior and posterior spinal arteries are reinforced along length by 8-10 segmental medullary arteries. the largest is the arteria radicularis magna or the artery of adamkiewicz - this arisse in lower thoracic or upper lumbar area and reinforces artery supply to lower part of spinal cord including lumbar enlargement
what are the two roots of each spinal nerve and what does the spinal nerve go on to form?
anterior and posterior.
the posterior root contains the process of sensory neurons carrying information to the CNS- the cell bodies of the sensory neurons which are derived from neural crest cells, are clustered in a spinal ganglion at the distal end of the posterior root usually in the intervertebral foramen.
the anterior root has motor nerve fibers, which carry signals away from the cns- the cell bodies of the primary motor neurons are in anterior reigons of the spinal cord.
-spinal segment gives rise to posterior and anterior rootlets which will form a single pair of spinal nerves. Laterally, the posterior and anterior roots on each side join to form a spinal nerve. The spinal nerve emerges from intervertebral foramen into two major branches- a small posterior ramus and a much larger anterior ramus
what do the posterior/anterior rami innervate
The posterior rami only innervate the intrinsic muscles of the back (epaxial) and an associated narrow strip of skin on the back
The anterior rami innervate most other skeletal muscles (hypaxial muscles) of the body, including limbs and trunk, and most remaining areas of the skin , except certain regions of the head.
what are the superficial group of back muscles?
Trapezius, latissmus dorsi, levator scapulae, rhomboid major, rhomboid minor
what is the trapezius function?
assists in rotating the scapula during abduction of humerus above horizontal- the upper fibers elevate and the middle fibers adduct. lower fibers depress scapula
what is the latissmus dorsi function?
extends, adducts, and medially rotates the humerus
