RVU Spinal Osteology, Chap 1

• Functional components include:
• a. vertebral body
• b. vertebral arch
• c. seven processes: three for muscle attachment and leverage and four that participate in synovial joints with adjacent vertebrae

• The vertebral column in an adult typically consists of 33 vertebrae arranged in five regions:
• 7 cervical
• 12 thoracic
• 5 lumbar
• 5 sacral
• 4 coccygeal

Significant motion occurs only between the 25 superior vertebrae. Of the 9 inferior vertebrae, the 5 sacral vertebrae are fused in adults to form the sacrum, and after approximately age 30, the 4 coccygeal vertebrae fuse to form the coccyx. The lumbosacral angle occurs at the junction of the long axes of the lumbar region of the vertebral column and the sacrum (Fig. 4.1D). The vertebrae gradually become larger as the vertebral column descends to the sacrum and then become progressively smaller toward the apex of the coccyx (Fig. 4.1A-D). The change in size is related to the fact that successive vertebrae bear increasing amounts of the body's weight as the column descends. The vertebrae reach maximum size immediately superior to the sacrum, which transfers the weight to the pelvic girdle at the sacroiliac joints

Sacral fusion patterns vary in about 5% of the population

• a. Sacralization-fusion of the 5th lumbar vertebra with the sacrum
• b. Lumbarization-LACK of fusion of the first sacral vertebra with the sacrum

• The vertebral body is
• a. Largest, more massive, anterior portion of the bone that gives strength to the vertebral column and supports body weight.
• b. size increases inferiorly, most markedly at T4
• c. composed of vascular, trabecular (spongy, cancellous) bone enclosed by a thin external layer of compact (cortical)bone (Fig. 4.3).
• d. cylindrically shaped roughened ends covered with discs of hyaline cartilage (vertebral “end plates”), which are remnants of the cartilaginous model from which the bone develops.

• *Additional info from COA book:
• The trabecular bone is a meshwork of mostly tall vertical trabeculae intersecting with short, horizontal trabeculae. The spaces between these trabeculae are occupied by red bone marrow that is among the most actively hematopoietic (blood-forming) tissues of the mature individual. One or more large foramina in the posterior surface of the body accommodate basivertebral veins that drain the marrow (see Fig. 4.26).
• In life, most of the superior and inferior surfaces of the vertebral body are covered with discs of hyaline cartilage (vertebral “end plates”), which are remnants of the cartilaginous model from which the bone develops.

In addition to serving as growth zones, the anular epiphyses and their cartilaginous remnants provide some protection to the vertebral bodies and permit some diffusion of fluid between the IV disc and the blood vessels (capillaries) in the vertebral body (see Fig. 4.26). The superior and inferior epiphyses usually unite with the centrum, the primary ossification center for the central mass of the vertebral body (Fig. 4.2B), early in adult life (at approximately age 25) (see “Ossification of Vertebrae,” p. 453).

• 
• The vertebral arch is posterior to the vertebral body and consists of two (right and left) pedicles and laminae (Fig. 4.2A & C).

• a. Pedicles-posterolateral processes which project from the body bilaterally to meet two broad, flat plates of bone, called laminae, which unite in the midline.
• 1)vertebral notches - superior and inferior indentations of the pedicle. When articulated these indentations on contiguous vertebrae form intervertebal foramina which allow for passage of the spinal nerves and vessels.

b. Laminae- continuation of pedicles posteromedially;fuse in the midline to complete the vertebral arch and enclose th vertebral foramen.

COA:

The vertebral arch and the posterior surface of the vertebral body form the walls of the vertebral foramen (Fig. 4.2A & B). The succession of vertebral foramina in the articulated vertebral column forms the vertebral canal (spinal canal), which contains the spinal cord and the roots of the spinal nerves that emerge from it, along with the membranes (meninges), fat, and vessels that surround and serve them (Figs. 4.1D and 4.3). (See the blue box “Laminectomy,” p. 457.)

Can be due to trauma, but most are from demineralization of the spongy bone. As the bone thins out, it is less able to support a load and the structural integrity of the vertebra is compromised resulting in a compression fracture.Therefore patients with osteoporosis may develop compression fractures without severe injuries, even in their daily activities.

• Symptoms
• *Back pain,most common problem
• *Patients w/osteoporosis & multiple com fractures may begin to notice a curving of spine, like a hunchback, aka kyphotic deformity. The reason for this is the vertebrae are compressed in front, and usually normal in back. This wedge shaped appearance causes the spine to curve forward.
• *loss of their overall height because of the decreased size of the spinal column.
• *Nerve complaints are unusual in compression fractures because the spine and its nerves are behind the vertebra and the front of the vertebra is compressed and the back remains normal. In some serious traumatic fractures, called "burst fractures," the compression occurs around the spinal cord and nerves. This is more serious and may require immediate treatment to prevent or relieve pressure on the spinal cord or nerves.

• vertebral spines from T7 to the sacrum, posterior third of the iliac crest, lower 3 or 4 ribs, sometimes from the inferior angle of the scapula
• floor of the intertubercular groove
• extends and rotates the arm medially, along with adduction of the arm
• thoracodorsal nerve (C7,8) from the posterior cord of the brachial plexus
• thoracodorsal a.
• the inserting tendon twists so that fibers originating highest insert lowest (Latin, latus = broad, dorsi = back)

Seven processes arise from the vertebral arch of a typical vertebra (Fig. 4.2A-C):

a. Spinous (1) median process projects posteriorly (and usually inferiorly, typically overlapping the vertebra below) from the vertebral arch at the junction(union) of the two laminae.

b. Transverse (2) bilateral processes project posterolaterally from the junctions of the pedicles and laminae.

*The spinous and transverse processes provide attachment for deep back muscles and serve as levers, facilitating the muscles that fix or change the position of the vertebrae.

c. Articular (4) processes (G. zygapophyses)—two superior and two inferior—also arise from the junctions of the pedicles and laminae, each bearing an articular surface (facet).

*The articular processes are in apposition with corresponding processes of vertebrae adjacent (superior and inferior) to them, forming zygapophysial (facet) joints (Fig. 4.2D). Through their participation in these joints, these processes determine the types of movement permitted and restricted between the adjacent vertebrae of each region.

*The articular processes also assist in keeping adjacent vertebrae aligned, particularly preventing one vertebra from slipping anteriorly on the vertebra below. Generally, the articular processes bear weight only temporarily, as when one rises from the flexed position, and unilaterally when the cervical vertebrae are laterally flexed to their limit. However, the inferior articular processes of the L5 vertebra bear weight even in the erect posture.

• Intervertebral disc (or intervertebral fibrocartilage):
• a. 33 total, one disc between adjacent vertebrae in the spine, except C1
• b. forms a cartilaginous joint to allow slight movement of the vertebrae
• c. acts as a ligament to hold the vertebrae together
• d. identified by specifying the particular vertebrae they separate. For example, the disc between the fifth and sixth cervical vertabrae is designated "C5-6".

• Discs consist of:
• *outer annulus fibrosus, which surrounds the
• *inner nucleus pulposus.

The annulus fibrosus consists of several layers of fibrocartilage. The strong annular fibers contain the nucleus pulposus and distribute pressure evenly across the disc. The nucleus pulposus contains loose fibers suspended in a mucoprotein gel with the consistency of jelly.

The nucleus of the disc acts as a shock absorber, absorbing the impact of the body's daily activities and keeping the two vertebrae separated. The disc can be likened to a doughnut: whereby the annulus fibrosis is similar to the dough and the nucleus pulposis is the jelly. If one presses down on the front of the doughnut the jelly moves posteriorly or to the back. When one develops a prolapsed disc the jelly/ nucleus pulposus is forced out of the doughnut/ disc and may put pressure on the nerve located near the disc. This can give one the symptoms of sciatica.

• 1.Lumbar vertebrae
• 2.Body
• 3.Vertebral foramen
• 4.Superior articular process
• 5.Transverse process
• 6.Inferior articular process
• 7.Spinous process

Orientation of articular facets on the articular processes in a characteristic direction determines the type of movement permitted between the adjacent vertebrae and, in aggregate, for the region.

For example, the articular facets of thoracic vertebrae are nearly vertical, and together define an arc centered in the IV disc; this arrangement permits rotation and lateral flexion of the vertebral column in this region (see Fig. 4.7). (Fig. 4.1D).

• C1-C7 form the skeleton of the neck (Fig. 4.1).
• 1)smallest of the 24 movable vertebrae, bear least weight
• 2)located between cranium and the thoracic vertebrae
• 3)Thinnest IV discs, but relatively thick compared to size of the vb they connect.
• 4)horizontal orientation of articular facets and small amount of surrounding body mass give greatest range and variety of movement of regions.

• A. Body
• 1.Small with lateral dimension greater than a/p dimension; superior surface concave with uncus of body (uncinate process); inferior surface convex
• 2. Rectangular

• B.Transverse processes
• 1. Arises from jxn of pedicle and articulating processes, anteriorly attached to costal processes which project from body of vertebra forming costotransverse foramen
• 2. ????if someone knows, please tell me?
• 3.Directed anterolateral

NOTE:oval foramen transversarium (transverse cervical foramen), most distinctive feature. The sympathetic nervous plexus and vertebral arteries/veins pass through the transverse foramina, except those in C7, which transmit only small accessory veins. Thus the foramina are smaller in C7 than those in other cervical vertebrae, and occasionally they are absent.Foramina transversarii and anterior and posterior tubercles.

• NOTE: Costal and transverse porcesses end laterally by forming a/p tubercles, respectively, provide sites for attachment of neck and superficial back musculature.
• C. Articular processes
• 1. Located posterior to the transverse process
• 2.*Superior facets directed superioposteriorly
• *Inferior facets directed inferioanteriorly
• *Obliquely placed facets are most nearly horizontal in this region
• D. Spinous processes
• 1. Short (C3-C5), but process of C6 long, C7 is longer-“vertebra prominens”
• 2. Bifid (C3-C6)
• 3. Downward projecting
• E. Vertebral arch or foramen
• 1. Large,triangularly shaped with apex directed posteriorly

NOTE:The C1 and C2 vertebrae are atypical

• A.) Body
• 1)Intermediate size, Heart-shaped T2-T10
• 2)2 costal facets per side
• a) Superior- at origin of pedicle
• b) Inferior- at lower edge of vertebra, immediately anterior to the inferior vertebral notch

• B)Tranverse Process
• 1)arise from the arch behind the superior articular processes and pedicles
• 2)Thick, Strong and long
• 3) Directed posterolateral
• *facet on its anterior surface is for articulation with the costal tubercle

• C) Articulating Process
• 1)Located at jxn of pedicle and lamina
• 2)Thin and flat
• 3)Orientated vertically in the coronal plane
• 4)Superior facets face posteriorly, superiorly, and somewhat laterally

• D)Spinous Process
• 1)long, triangular on coronal section
• 2)directed obliquely inferiorly (downward),ends in a tuberculated extremity
• 3)processes overlap from TV5-TV8 but are less oblique in direction above and below.

• E) Vertebral foramen
• 1) Circular most narrow diameter of entire column

• 2)source of much body motion and supports most of the body weight
• 3)lumbar vertebrae are the largest segments of the movable part of the vertebral column
• 4)characterized by the absence of the foramen transversarium within the transverse process
• 5)absence of facets on the sides of the body (no ribs)
• 6)

• A. Body
• 1)increased in size due to increased weight bearing capacity
• 2) wider laterally than A to P, and a little thicker A than P

• B)Transverse Processes
• 1) lie anterior to articulating processes
• 2) directed laterally

• C) Articulating processes
• 1)are well-defined, projecting respectively upward and downward from the jxns of pedicles and laminae
• 2)oriented vertically in the sagittal plan
• * Superior -face medially and somewhat posteriorly
• * Inferior -face laterally and somewhat anteriorly
• D) Spinous processes
• 1)thick and stong,
• 2)project directly dorsalward to provide area for erector spinae muscle attachment

• E) Vertebral foramen
• 1) within the arch is triangular shaped with the apex directed posteriorly, larger than in the thoracic vertebrae, but smaller than in the cervical vertebrae
• NOTE :Lamina are short and non-overlapping: Facilitate lumbar puncture
• The laminae are broad, short, and strong. They form the posterior portion of the vertebral arch. The lamina connect the spinous process to the pedicles.

• Sacrum represents the fusion of five vertebrae
• A.

• * C7 vertebra prominens
• * C1 Atlas
• *C2 Axis
• *TV 1,10,11,12

round nodule, small eminence, or warty outgrowth found on bones, skin, or within the lungs in tuberculosis.

An articular facet (or articular surface) is a surface where two anatomical structures (usually bones) meet.

A sulcus (pronounced with a hard c) (pl. sulci) is a depression or fissure in the surface of an organ, especially the brain.

Obliquus capitis inferior

• Origin: spinous process of axis (C2)
• Insertion: transverse process of atlas (C1)
• Action: rotates the head to the contracted side
• Blood: muscular branches of vertebral artery
• Nerve: suboccipital nerve, (dorsal rami C1)

Rectus capitis posterior major

• Origin: spinous process of axis (C2)
• Insertion: inferior nuchal line (lateral to minor)
• Action:
• bilaterally extends the head
• rotates the head to the contracted side
• Blood: muscular branches of vertebral artery
• Nerve: suboccipital nerve, (dorsal rami C1)

Considered atypical because they have complete superior costal facets for the head of corresponding ribs. The contiguous T2-8, sometimes 9, have costal facets (demi facets) that form a "cup shaped" receptacle for the head of the rib.

• T1
• a)entire articular facet for the head of the first rib
• b)demi-facet for the upper half of the head of the second rib
• c)body = cervical vertebra- broad transversely;upper surface is concave and lipped on either side.
• d)superior articular surfaces are directed upward and backward
• e)spinous process is thick, long, and almost horizontal.
• f) transverse processes are longer than TV
• g)upper vertebral notches are deeper than other TV

• T9
• may have no demi-facets below. In some subjects however, it has two demi-facets on either side; when this occurs the tenth doesn't have facets but demi-facets at the upper part.

• T10
• a) entire articular facet (not demi-facet) on either side, which is placed partly on the lateral surface of the pedicle.
• b) no kind of facet below, because the following ribs only have one facet on their heads.

• T11
• a) Body approaches in its form and size to that of the lumbar vertebrae.
• b) articular facets for the heads of the ribs are of large size, and placed chiefly on the pedicles-thickest and strongest (T11 and T12) of entire region
• c)spinous process is short, and nearly horizontal in direction.
• d) transverse processes are very short, tuberculated at their extremities, and have no articular facets.

• T12
• a)same general characteristics as the eleventh
• b)resemblance or lumbar vertbrae in:
• * inferior articular surfaces being convex and directed lateralward
• * body
• * laminae
• * and spinous process
• And by each transverse process being subdivided into three elevations, the superior, inferior, and lateral tubercles:
• *superior and inferior correspond to the mammillary and accessory processes of the lumbar vertebrae. Traces of similar elevations are found on the transverse processes of the tenth and eleventh thoracic vertebrae.

• First cervical vertabra, NO BODY. Constructed of 2 lateral masses connected by A/P arches
• a) Anterior Arch
• * Tubercle
• *Facet for dens of CV₂
• b) Posterior Arch
• *Tubercle
• *Sulcus for vertebral artery
• c) Lateral masses
• 1.)large, articulating facets
• * Superior -articulate with the occipital condyles of the skull
• *Inferior - articulate with the superior articulating facets of the axis, C2
• 2.) Tranverse process-the widest of the cervical vertebrae, well developed more laterally placed than those of the inferior vertebrae,providing increased leverage for attached muscles to rotate head
• d.) Vertebral foramen - enlarged to accomodate the caudal medulla(brain stem)
• 

• bifid
• [bī′fid]
• Etymology: L, bis + findere to cleave

cleft, or split into two parts, as in the spinous processes of the cervical vertebrae.

• a)Body of CV₂ incorporates body of CV₁ as the odontoid process (dens) which rises perpendicularly from the upper surface of the body. Dens is greatest distinction
• b) Dens has smooth anterior articulating facet which receives the anterior arch
• c) Superior articulating facets are modified to articulate with CV_1, The inferior articular surfaces have the same direction as those of the other cervical vertebrae
• d) Spinous process is thick and bifid
• 

• a) Transition between cervical and thoracic regions
• b) Long, nearly horizontal spinous process,easily palpable
• c)Transverse foramen are small, frequently absent.When present, transmit vertebral VEIN, NOT artery

• Conus medullaris(located at L2)is the tapered termination of the spinal cord proper.
• The Cauda Equina. In human, the spinal cord ends at L2 vertebral level. The tip of the spinal cord is called the conus. Below the conus, there is a spray of spinal roots that is frequently called the cauda equina or horse's tail. Injuries below L2 usually involve the cauda equina and represent injuries to spinal roots rather than the spinal cord proper.

The caudal epidural block is a popular choice for participatory childbirth (B in Fig. B3.27). It must be administered in advance of the actual delivery, which is not possible with a precipitous birth. The anesthetic agent is administered using an in-dwelling catheter in the sacral canal, enabling

• P.399administration of more anesthetic agent for a deeper or more prolonged anesthesia, if necessary. Within the sacral canal, the anesthesia bathes the S2-S4 spinal nerve roots, including the pain fibers from the uterine cervix and superior vagina, and the afferent fibers from the pudendal nerve. Thus the entire birth canal, pelvic floor, and majority of the perineum are anesthetized, but the lower limbs are not usually affected.
• The pain fibers from the uterine body (superior to the pelvic pain line) ascend to the inferior thoracic-superior lumbar levels; these and the fibers superior to them are not affected by the anesthetic, so the mother is aware of her uterine contractions. With epidural anesthesia, no “spinal headache” occurs because the vertebral epidural space is not continuous with the cranial epidural space (see Chapter 4).

• Lumbar Spinal Puncture
• Lumbar puncture (LP, spinal tap), the withdrawal of CSF from the lumbar cistern, is an important diagnostic tool for evaluating a variety of central nervous system (CNS) disorders. Meningitis and diseases of the CNS may alter the cells in the CSF or change the concentration of its chemical constituents. Examination of CSF can also determine if blood is present.
• LP is performed with the patient lying on the side with the back and hips flexed (knee-chest position, Fig. B4.18). Flexion of the vertebral column facilitates insertion of the needle by spreading apart the vertebral laminae and spinous processes, stretching the ligamenta flava.

• The skin covering the lower lumbar vertebrae is anesthetized, and a lumbar puncture needle, fitted with a stylet, is inserted in the midline between the spinous processes of the L3 and L4 (or L4 and L5) vertebrae. Recall that a plane transecting the highest points of the iliac crests—the supracristal plane—usually passes through the L4 spinous process. At these levels, there is no danger of damaging the spinal cord.
• After passing 4-6 cm in adults (more in obese persons), the needle “pops” through the ligamentun flavum, then puncturing the dura and arachnoid and enters the lumbar cistern.

• P.506When the stylet is removed, CSF escapes at the rate of approximately one drop per second. If subarachnoid pressure is high, CSF flows out or escapes as a jet.
• Lumbar puncture is not performed in the presence of increased intracranial pressure (within the cranial cavity). The intracranial pressure is generally previously determined by CT scanning, but may also be determined by examination of the fundus (back) of the interior of the eyeball with an ophthalmoscope (

Because of their more horizontally oriented articular facets, the cervical vertebrae are less tightly interlocked than other vertebrae. The cervical vertebrae, stacked like coins, can be dislocated in neck injuries with less force than is required to fracture them (Fig. B4.3A-F). Because of the large vertebral canal in the cervical region, slight dislocation can occur here without damaging the spinal cord (Fig. B4.3B). Severe dislocations, or dislocations combined with fractures (fracture-dislocations) injure the spinal cord. If the dislocation does not result in “facet jumping” with locking of the displaced articular processes (Fig. B4.3F & G), the cervical vertebrae may self-reduce (slip back into place) so that a radiograph may not indicate that the cord has been injured. An MRI, however, may reveal the resulting soft tissue damage.