The Spine

The spine consists of three basic elements: bones, joints, and neural tissue. Together these components allow the spinal column to perform a variety of functions in the human body. The weight of the body is transferred through the vertebrae and disks; motion occurs through the intervertebral joints and disks; and the brainstem, spinal cord, and spinal nerves that travel in and around these bones and joints are allowed to function in a protected environment.

The body has three main neural components: the central, peripheral, and autonomic nervous systems. The central nervous system consists of the brain, brainstem, and spinal cord. Protecting the spinal cord and spinal nerves are the meninges, composed of the dura mater, pia mater, and arachnoid. These protective layers help protect and isolate the central nervous system from the outside world. The brainstem and spinal cord travel within a tunnel-like structure called the spinal canal. The spinal cord gives rise to 31 pairs of spinal nerves or nerve roots that branch off along the length of the spinal cord and exit from the spinal canal through a tunnel called the foramen. After these nerve roots exit from the spine, they join other nerves to become peripheral nerves. Peripheral nerves contain the sensory fibers, voluntary muscle fibers, and fibers of the autonomic nervous system. The autonomic nervous system is composed of small nerve branches arising from the central nervous system and supplying ganglia, which are clusters of cells near but outside the bony limits of the vertebrae. The sympathetic nervous system and parasympathetic nervous systems are subdivisions of the autonomic nervous system, which is involved in the control of visceral organs and blood vessels. Most spinal nerves and peripheral nerves contain a mixture of sensory and motor fibers that supply specific muscles and provide sensation in particular locations in the body. By treating the anatomy of the spinal cord and its peripheral branches like a road map, a physician can often determine the cause of numbness, tingling, or weakness found on a sensory and motor examination.

The spine is made of bony segments known as vertebrae. These are separated by intervertebral disks and facet joints that permit motion. A complex arrangement of ligaments and muscles provide stability and motion of the spinal column. Neural elements exit and enter the spinal column through openings called foramina.

Each component of the spinal column depends on the others to function normally. If one part of the spine changes in character, such as in a fracture or a disk herniation, other structures can be affected, leading to arthritis, muscle fatigue, nerve or spinal cord damage, or irritation resulting in pain, numbness, weakness, or even paralysis in severe cases.

General Anatomy of the Spine

The 32 vertebrae composing the spinal segments are divided into five regions, with the segments numbered from top to bottom. There are usually 5 cervical, 12 thoracic, 5 lumbar, 5 sacral, and several coccygeal vertebrae; however, there are anatomic variants, such as the presence of “transitional vertebrae” at the ends of spinal segments ( Fig. 9-1 ).

Fig. 9-1Diagram showing the relation of the segments of the spinal cord and nerves to the segments of the vertebral column. (From Hamilton WJ, editor: Textbook of human anatomy, ed 2, London, England, 1976, The Macmillan Press, Ltd.)

A vertebra is labeled by segment such as C-5, L-4, and S-1. The intervertebral disk is labeled for the level of the vertebrae between which the disk exists.

  • cervical spine: seven spinal segments (C1–C7) and eight cervical nerve roots (C1–C8) between the base of the skull (occiput) and the thoracic spine. The cervical spine differs from the rest of the vertebrae in one major aspect: the numbered nerve roots exit the spinal canal above the correspondingly numbered vertebra’s pedicle instead of below it.

  • thoracic spine (dorsal spine): 12 spinal segments (T1–T12) incorporating the 12 ribs of the thorax. Other than a slight increase in size from top to bottom, they are fairly uniform in appearance.

  • lumbar spine: five mobile segments of the lower back (L-1 to L-5). These are the largest of the vertebral segments.

  • sacral spine: five fused segments of the lower spine that connect to the pelvis and have four foramina on each side; also called sacrum.

  • coccygeal spine: remaining three or four, somewhat fixed, fused segments at the end of the spine (tailbone) that articulate with sacrum above; also called coccyx.

Except for the coccyx, sacrum, and the first cervical spine, there are anatomic parts that are common to all 32 spinal segments. Moving from anterior to posterior (front to back), the main vertebral parts are the following.

  • facet joint: small articular cartilage-surfaced joints connecting the posterior elements of one spine to the posterior elements of the neighboring spine; also called zygapophyseal joint.

  • foramen: an opening allowing for the egress of spinal nerve roots from between two vertebrae.

  • intramedullary: refers to medullaris, marrow; (1) within the medulla oblongata of the brain, (2) within the spinal cord, and (3) within the marrow cavity of bone.

  • lamina: the posterior part of the spinal ring that covers the spinal cord or nerves.

  • pars interarticularis: the posterior continuation of the spinal arch from the pedicle; the superior and inferior facets are connected to each other by the pars interarticularis.

  • pedicle: the first portion of the posterior spine arising from the vertebral body.

  • spinous process: the most posterior extension of the spine arising from the laminae.

  • transverse process: bony process arising from midportion of the spinal ring just posterior to the pedicle and pars interarticularis.

  • vertebral body: from a lateral view, it is the main rectangular portion; from an overhead view, oval ( Fig. 9-2 ).

    Fig. 9-2Vertebral body and posterior elements.

Cervical Spine Anatomy

Bones and Landmarks

  • atlas: the first cervical vertebra (C1), lying directly under the skull, through which the head articulates with the neck. The main connection to the vertebra below is a pivot around the odontoid process that is an upward projection of the body of the second cervical vertebra. The atlas is held to the odontoid by a ligament complex attaching it to the odontoid anteriorly and facet joints posteriorly, allowing rotation, flexion, and extension between C1 and C2.

  • axis: the second cervical vertebra (C2), about which the first cervical vertebra rotates, allowing head movement. It bears the odontoid process, the projecting part of the second cervical vertebra, which allows the first cervical vertebra (atlas) to rotate.

  • carotid tubercle: prominence of the transverse process of C6 felt on the lateral side of neck.

  • chondrum terminale: in young children, a cartilaginous epiphysis at the tip of the odontoid. The fusion takes place at 10–12 years and is the weak point at the C1–C2 junction in younger children.

  • cricoid ring: cartilage ring above the trachea and below the thyroid cartilage; the first cricoid ring is at the level of C6.

  • hyoid bone: small, vertically oriented bone lateral to trachea, located at the level of C3.

  • joints of Luschka: unique to the cervical spine, these jointlike structures are formed by the apposition of posterolateral portions of adjacent vertebral bodies; forms the anterior portion of the canal where nerves pass through; also called uncovertebral joints.

  • lateral mass: the lateral expansion of the spinal ring in the cervical spine, consisting of the facet joints and intervening bone as well as a tunnel through which the vertebral artery travels in the second through seventh cervical vertebra.

  • occiput: the base of the skull.

  • thyroid cartilage: widening expanses of cartilage above the trachea; the top marks the level of C4, and the bottom C5.


  • longissimus colli: long muscle immediately anterior to the cervical spine.

  • platysma: thin, outermost muscle layer of the anterior neck.

  • posterior neck muscles: splenius m., spinalis m., and semispinalis m.

  • scalenus: the deep lateral muscles of the anterior neck, including anterior scalene m. (scalenus anticus), middle scalene m. (scalenus medius), and posterior scalene m. (scalenus posticus).

  • sternocleidomastoid: large, externally visible muscle of the anterior neck, enabling head to turn to either side.

  • strap muscles: a general term applied to the ribbonlike muscles in the anterior neck; they include omohyoid, sternohyoid, sternothyroid, and thyrohyoid.

Arteries and Veins

  • carotid artery: main artery to the head that divides into external and internal carotid arteries.

  • jugular vein: large, obvious vein in the neck.

  • other arteries and veins: transcervical, facial, superior thyroid, and inferior thyroid.

  • vertebral artery: large artery that travels in the lateral masses of the cervical spine and eventually supplies the lower brainstem.


  • cervical plexus: plexus of nerves that supply the neck muscles with branches named by muscles supplied, a portion of which is called the ansa cervicalis.

  • facial nerve: supplies some facial muscles and sensation; also called seventh cranial n.

  • laryngeal n. and recurrent laryngeal n.: branches of the vagus nerve important in anterior neck surgery.

  • occipital n.: nerve from the back of the neck that supplies motor function and sensation to the forehead; two parts—greater and lesser.

  • phrenic n.: nerve arising from three cervical nerve roots (C3–C5); supplies the diaphragm.

  • spinal accessory n.: the nerve from the brainstem that supplies the sternocleidomastoid muscles; also called eleventh cranial n.

  • vagus n.: the long nerve in the anterior neck traveling with the carotid artery; responsible for many organ functions in the chest and abdomen; also called tenth cranial n.

Other Structures

  • esophagus: portion of the gut between the mouth and stomach in the anterior neck.

  • interspinous ligament: ligament between each of the spinal processes.

  • nuchal ligament: large posterior midline ligament in the neck from the base of the skull to the seventh cervical vertebra.

  • thyroid gland: near the Adam’s apple; responsible for secretion of hormone that is involved in regulation of the rate of the metabolism.

  • trachea: the windpipe.

  • triangles: for surgical approaches and other considerations, the anterior half of the neck is divided into triangles—anterior, digastric, posterior, submental, and carotid.

Thoracic Spine Anatomy

  • costo-: combining form denoting relation to ribs.

  • costochondral junction: junction of the rib into cartilage in the anterior chest. NOTE: Most of the ribs have attachment to the cartilage rather than a direct junction with the breast bone.

  • costovertebral angle: juncture of tissue inferior and lateral to the twelfth rib and vertebral body.

  • costovertebral joint: junction of the rib with the thoracic spine.

  • diaphragm: the muscle between the abdomen and thorax; main muscle of normal breathing.

  • intercostal m.: the muscles between the ribs.

  • latissimus dorsi m.: large muscle arising from posterior thoracic spine and attaching at proximal humerus.

  • pectoralis m.: from sternum and ribs to humerus.

  • rotator cuff muscles: include supraspinatus m., infraspinatus m., subscapularis m., and teres minor m.

  • sternum: the breast bone; further divided into three segments.

    • manubrium: upper portion, proximal end

    • sternum: main portion, medial portion

    • xiphoid: the daggerlike tip of the sternum, distal end

  • thorax: the chest or rib cage; also refers to the space containing the lungs and heart. There are 12 vertebral segments and ribs; the lower two are called floating ribs.

Lumbar and Lower Spine Anatomy


  • coccyx: the three, and sometimes four, segments of bone just below the sacrum; referred to as the tailbone ; the end of the spinal column.

  • lumbar spine: the five movable spinal segments of the lower back and largest of the spinal segments.

  • sacral ala: lateral portions of the sacral bone.

  • sacral spine (sacrum): the five segments fused together as a solid bone and below the last lumbar segment position.

  • sacroiliac joint: the junction between the sacrum and the ilium; resembles a large ear.

Disk and Spinal Canal

  • intervertebral disk: the structure that normally occupies the space between two moving vertebrae and acts to distribute forces through surrounding structure such as the facet joints, subchondral plate, and ligaments. It is more prominent in the cervical and lumbar spines. The centermost portion of the disk (nucleus pulposus) is normally composed of a gelatinous material that varies in consistency from a firm jelly material to a very thick and less pliable substance. This core is then surrounded by numerous layers of fibrous (fibrocartilaginous) material called the annulus fibrosus. That structure goes to the normal margins of the vertebral body, called the anterior longitudinal ligament, and to those on the spinal canal side posteriorly, the posterior longitudinal ligament. Also called interspinal disk.

  • ligamentum flavum: a band of yellow elastic tissue that runs between the laminae from the axis to the sacrum; it assists in maintaining or regaining erect position and serves to close in the spaces between the arches. Hypertrophy and infolding of the ligamentum flavum is often a source of spinal stenosis. It is important as a surgical structure in that a portion is usually removed during an exploration of the spinal canal.

  • spinal canal: the space between the vertebral body anteriorly and the lamina and spinal process posteriorly. The spinal cord extends to the level of the second lumbar segment in adults and the second sacral segment in infants. Below this level are numerous spinal nerves from the spinal cord. This lower portion resembles a horse’s tail and is referred to as the cauda equina (“horse’s tail” in Latin). The lower tip of the spinal cord is attached to the end of the spinal canal by a single filament called the filum terminale. The brain, spinal cord, and spinal nerves float in a waterlike substance called the cerebral spinal fluid. This fluid is contained in a thin sac called the meninges. The thick, outer portion of that sac is called the dura or dura mater. The more flimsy inner coverings are the arachnoid (Latin for “spiderlike”) and pia. The dura extends over the nerve roots out into the foramina. This saclike covering is called the nerve root sleeve. The dura also extends within the spinal canal down to the level of the second sacral segment. Any space within the dura from the first cervical to the second sacral level is considered intradural.

  • spinal cord: the part of the central nervous system below the level of the brainstem and above the cauda equina in the regions of the cervical, thoracic, and upper lumbar spines. Usually, the orthopaedist does not deal with the spinal cord—that is for the neurosurgeon. Based on training, both the orthopaedist and neurosurgeon deal with spinal cord problems. Many of these conditions can result in peripheral neuromuscular disorders.

    • dorsal column: the main, normal sensory tract to the brain.

    • dorsal lateral column: the main tract of position and tone to the brain.

    • gray matter: the nerve cell bodies to muscle and sensory outflow and input, respectively; also called anterior and posterior horns.

    • long tracts: the nerve fibers that connect the spinal cord with the brain; main spinal nerve pathways.

    • pyramidal tract: carries the voluntary muscle messages from the brain.

    • spinal thalamic tract: the main tract of pain to the brain.


  • abdominal muscles: important for support of the spine; these muscles are the rectus abdominis m., external oblique m., internal oblique m., and transversus m.

  • iliopsoas muscle: large muscle starting at L1 and becoming wider as it picks up segments from the lower lumbar spine; combines with the iliacus m. muscle before attaching to the lesser trochanter of the hip.

  • posterior spinal muscle segments: upper and lower posterior serratus m., spinalis m., semispinalis m., and rotators.

  • quadratus lumborum m.: a muscle lateral to the iliopsoas muscle of the spine running from the lower ribs to the ilium.


  • artery of Adamkiewicz: an important source of blood supply to the lower portion of the spine, usually occurring at the levels of T9 to T11 and arising from the left side of the aorta; however, it is not the only blood supply to the cord at that level.

Diseases and Structural Anomalies

Back and Neck Diseases

The spine is a complex organ that is a series of joints with attending bone, nerve tissues, muscles, and ligaments. In addition, there are two elements not common to other joints, namely, intervertebral disks and the spinal cord and nerves in the bony spinal canal. The nerves may be affected by either bone or disk disease; therefore this section is divided into discussions of diseases affecting bone, nerves, spinal cord, vertebral disks, and congenital disorders.

The orthopedist treats abnormalities of the spine that cause deformities or result in injury to neurological structures, such as the spinal cord or nerves. Other specialties, such as neurosurgery or physical medicine and rehabilitation, also provide operative and non-operative care for spinal conditions.

General Bone Diseases of the Spine

The Latin word vertebra and the combining form spondylo – both denote the bony spinal segments. In some word combinations, the root word is assigned only to a specific part of the vertebra, such as spondylolysis in which the defect is always at the pars interarticularis. However, spondylo- in general means “vertebra.”

Spondylo- Root Diseases

  • destructive spondyloarthropathy : focal destruction on non-infectious origin seen in renal dialysis patients wherein the precise mechanism is not clear.

  • spondylalgia: pain in vertebrae.

  • spondylarthritis: arthritis of the spine.

  • spondylarthrocace: tuberculosis of the spine; also called spondylocace.

  • spondylexarthrosis: dislocation of a vertebra.

  • spondylitis: inflammatory disease involving the spine with inflammation of vertebrae, including types such as ankylosing, rheumatoid, traumatic, spondylitis deformans, Kümmell, and Marie-Strümpell d.

  • spondylizema: depression or downward displacement of a vertebra, with destruction or softening of one below it.

  • spondylocostal dysostosis: a rare autosomal recessive growth disorder characterized by potentially severe malformations of the vertebrae and ribs.

  • spondylodynia: pain in vertebrae.

  • spondyloepiphyseal dysplasia: disorder of growth affecting both the spine and the ends of long bones.

  • spondylolisthesis: usually an anterior displacement of one vertebra on the adjacent lower vertebra. When the superior segment is posterior to the inferior one, it is called a retrolisthesis. Many, but not all, patients with spondylolisthesis have spondylolysis. Spondylolisthesis is a general term with multiple distinctions:

    • anterior displacement: forward movement of the superior segment on the inferior one.

    • lumbar lordosis: angle made by lines drawn from the superior surface of the first and fifth lumbar vertebrae.

    • lumbosacral joint angle: angle between the inferior surface of the fifth lumbar vertebra and the top of the sacrum.

    • pelvic incidence: angle between a line perpendicular to the center of the superior sacral endplate and a line from the sacral endplate to the center of the femoral head. This is considered a “fixed” measurement and is unchanged by patient positioning. It can also be calculated as pelvic tilt + sacral slope.

    • pelvic tilt: angle between a line perpendicular to the center of the superior sacral endplate and a vertical line

    • rounding of the cranial border: relationship of the height to the width of the rounded portion of the superior sacrum.

    • sacral inclination: relationship of the sagittal plane of the sacrum to the vertical plane.

    • sacrohorizontal angle (sacral slope): angle between the top of the sacrum and the horizontal line.

    • sagittal balance (C7 plumb line): relationship between a vertical line from the middle of the C7 vertebral body and the posterosuperior corner of the S1 vertebral body. There is neutral balance if the plumb line passes within 2 cm of the S1 vertebral body. There is positive balance if the plumb line passes in front of the S1 vertebral body and negative balance if it passes behind the S1 vertebral body.

    • sagittal rotation: denotes an abnormal angular relationship between the body of the fifth lumbar vertebra and the sacrum; also called sagittal roll, lumbosacral kyphosis, and slip angle.

    • wedging of olisthetic vertebra: measure obtained by dividing the height of the anterior border of the fifth vertebra by the height of its posterior border, multiplied by 100.

  • spondylolysis: a fracture or defect in the pars interarticularis (a portion of bone between each of the joints of the spine), allowing one vertebral body to slide forward on the next ( Fig. 9-3 ). May be referred to as pars interarticularis defect. Patients with spondylolysis do not always have spondylolisthesis.

    Fig. 9-3 A, Oblique view: A, Articular facet joint; I, isthmus or pars interarticulars; T, transverse process; L, lamina; P, pedicle. The oblique view visualizes the so-called Scottie dog. Spondylolysis occurs through the isthmus ( arrow ). B, Bony defect ( arrow ) in the isthmus or neck of the Scottie dog present in spondylolysis (oblique view). C, Meyerding’s classification of spondylolisthesis. The amount of slippage is graded 1–4. Grade 1 represents 25% forward displacement; grade 2, 25%–50%; grade 3, 50%–75%; and grade 4, greater than 75%. D, Spondylolisthesis of the lumbosacral junction. (From Mercier LR: Practical orthopaedics, ed 5, St Louis, 2000, Mosby.)

  • spondylolysis, pathologic: generalized or localized bone disease is present.

  • spondylomalacia: softening of vertebrae; also called Kümmell disease.

  • spondylopathy: any vertebral disorder.

  • spondylopyosis: infection in vertebrae.

  • spondyloschisis: congenital fissure (splitting) of vertebral arch.

  • spondylosis: bony replacement of ligaments around the disk spaces of the spine, associated with decreased mobility and eventual fusion; also called marginal osteophyte.

Rachio- Root Diseases

Rachio -, as relating to spine, is less frequently used than more specific combining forms.

  • rachialgia: pain in the vertebral column.

  • rachiocampsis: curvature of the spine.

  • rachiochysis: effusion of fluid within the vertebral canal.

  • rachiodynia: pain in the spinal column.

  • rachiokyphosis: humpbacked curvature of spine; kyphosis.

  • rachiomyelitis: inflammation of the spinal cord.

  • rachioparalysis: paralysis of the spinal muscles.

  • rachiopathy: any disease of the spine.

  • rachioplegia: spinal paralysis.

  • rachioscoliosis: lateral curvature of the spine.

  • rachisagra: pain or gout in the spine.

  • rachischisis: congenital fissure of the spinal cord.

Miscellaneous Spinal Disorders

  • alar dysgenesis: abnormality in development of the sacroiliac joint.

  • anisospondyly: different abnormal shapes of the vertebral bodies.

  • ankylosing spinal hyperostosis: arthritic disorder in which bridging osteophytes located anteriorly and posteriorly on the vertebral body bind two or more vertebrae together; also called Forestier disease.

  • anterior spurring: ligament turning to bone on anterior side of vertebral body.

  • Baastrup d.: false joint formed by wide posterior spinous processes of the lumbar spine. This may become a source of pain. Also called kissing spine.

  • camptocormia: severe forward flexion of upper torso, usually an excessive psychologic reaction to back pain.

  • cervical rib: riblike structure in the seventh cervical vertebra that may cause nerve root irritation.

  • coccyalgia: pain in the coccyx region; also called coccygodynia, coccyodynia, and coccydynia.

  • crankshaft phenomenon: progressions of a spinal curve caused by continued growth of the unfused anterior aspect of the spine following a posterior spine fusion for scoliosis in children. The deformity can be severe with increased lordosis and rotation despite little change in the curve as measured on an anterior-posterior radiograph.

  • dysraphism: any failure of closure of the primary neural tube. This general category includes the disorder myelomeningocele. This definition includes the conditions in which there is an abnormal midline structure in the neural axis. Hence, diastematomyelia, in which the midline structure has fused, but the term also implies a bony spike from the anterior-lying vertebral body.

  • epidural pneumorrhachis: Typically due to a surgical procedure the insufflation of air in the epidural space potentially leading to neurologic findings.

  • facet tropism: asymmetrical orientation of the facets comparing right to left side.

  • Grisel syndrome: subluxation of the atlantoaxial joint from inflammatory ligamentous laxity caused by infection. Can result in neurologic complications.

  • interspinous pseudarthrosis: formation of a false joint between two spinous processes.

  • junctional failure: a more severe form of junctional kyphosis.

  • junctional kyphosis: the development of kyphosis above a posterior spinal fusion construct with Cobb angle change 10 O or greater.

  • limbus annulare: a mass of bone situated at the anterosuperior margin of a vertebra. Arises from failure of fusion of the primary and secondary ossification centers.

  • lumbarization: partial or complete formation of a free-moving first sacral segment so that it looks like a lumbar vertebra.

  • marginal osteophytes: excess bone formation at the margin of the vertebral body; also called spondylosis.

  • olisthy: slipping of bones from normal anatomic site; for example, a slipped disk.

  • paravertebral muscle spasm: spasm in the muscles on either side of the spinous processes (midline of the back); the term may be used to describe a physical finding or improperly used to define a disease process.

  • pseudoclaudication: increased pain and decreased strength in lower limbs associated with physical activity. Complaints are similar to those caused by an insufficient blood supply to the limb but are caused by diminished blood supply to the nerves in a narrowed spinal canal.

  • retrolisthesis: posterior displacement of the vertebra on the one below.

  • Redlund-Johnell: an alternative method for measuring vertical dislocation of C1 and C2 vertebrae in rheumatoid arthritis based on the distance from lower endplate of C2 to the palatooccipital or McGregor’s line.

  • rudimentary ribs: nubbins of ribs seen below the level where the last rib normally occurs.

  • sacralgia: pain in the sacrum.

  • sacralization: fusion of L5 to the first segment of the sacrum, so that the sacrum consists of six segments; this abnormality is called Bertolotti syndrome.

  • sacralized transverse process: one or both of the lumbar spinous transverse processes abnormally joining with the sacrum; also called sacralization.

  • sacrodynia: pain perceived to be in the area of the sacrum but may originate elsewhere.

  • sacroiliitis: inflammation of the sacroiliac joint. A very painful, often one-sided sacral area pain that follows delivery, is not due to sepsis, and will subside gradually and completely. A form is acute postpartum sacroiliitis.

  • sciatica: pain radiating down the sciatic nerve into the posterior thigh and leg; can be caused by irritation of a nerve anywhere from the back to the thigh.

  • scoliorachitis: disease of the spine caused by rickets; abnormal bone mineralization.

Spinal Deformities

Spinal deformity is the abnormal angulation of the spinal column when a person is viewed from the back or the side. It can occur from a variety of causes and at any age. An inclinometer is a device used to measure the amount of trunk rotation on examination.

Structural Anomalies

Scoliosis is a general term that applies to any side-to-side curve in the back, that is, a lateral and rotational deviation of the spine from the midline. Such a curve may be termed fixed curve, which means that any attempt to eliminate the curve by motion is not successful. A compensatory curve has a flexible segment above or below the fixed curve; this compensation will place the spine (above or below) into a vertical position with the head at the midline. The rotation of the spinous process is away from the apex of the curve. Levorotatory scoliosis means that this rotation of the most dorsal element of the spine is to the left if one is looking at the patient from behind. Dextrorotoscoliosis is the opposite condition. The apex of a curve is called the convex side, for example, a right lumbar scoliosis is a lateral deviation of the spine in the lumbar region, with the apex of that curve to the right; the concave side of the curve is the opposite side.

Scoliosis may be associated with vertebral anomalies (missing parts of the vertebrae) and with forward bending (round back); the latter is called kyphoscoliosis. Scoliosis may occur at birth (congenital), occur from known causes or diseases (acquired), or occur from unknown causes (idiopathic). An example will best illustrate the terminology. In a right thoracic, left lumbar, uncompensated rotatory scoliosis, viewed from behind, the upper back curves to the right and the lower back to the left; there is rotation of the spine, which may or may not be in both curves (unless so stated); and the center of the head is not in the midline when the patient is standing ( Fig. 9-4 ).

Fig. 9-4Scoliosis. A, Normal. B, Right convex curve, uncentered. C, Right convex curve, centered. (From the American Orthopaedic Association: Manual of orthopaedic surgery, ed 5, Chicago, 1979, The Association.)

Spinal Deformities and Conditions

  • adolescent scoliosis: lateral curvature of the spine occurring during adolescence.

  • adult scoliosis: scoliosis occurring after skeletal maturity.

  • chin-on-chest deformity: seen in ankylosing spondylitis, a marked kyphosis with fixed posturing of chin on chest.

  • Cobb syndrome: cutaneous vascular marking associated with spinal vascular formation within the same metameric (segmented) region.

  • compensatory curve: a curve located above or below a rigid structural curve to maintain normal overall body alignment.

  • congenital scoliosis: scoliosis caused by bony abnormalities present at birth involving either failure of formation of a vertebra or separation of adjacent vertebrae.

  • double curve: two lateral curves in a single spine; double major curve is two lateral curves of equal magnitude, and double thoracic curve is two thoracic curves.

  • exotic scoliosis: early onset spinal deformity that is more complex.

  • flattening of normal lumbar curve: condition in which the hollow of the back becomes shallow or even straight.

  • functional scoliosis: any scoliosis that is caused by leg length or other functional disorder and not by a primary curvature of the spine.

  • gibbus: most commonly used for spine deformity; a hump or exaggerated convexity.

  • idiopathic scoliosis: structural lateral curvature of an unknown cause.

  • infantile scoliosis: lateral curvature of the spine that begins before age 3.

  • juvenile scoliosis: begins between the ages of 3 and 10 years of age.

  • kyphoscoliosis: lateral curvature of the spine associated with forward inclination of the spine.

  • kyphosis: round shoulder deformity, humpback, dorsal kyphotic curvature; may refer to any forward-bending area or deformity of the spine.

  • lordoscoliosis: lateral curvature of the spine associated with backward bending of the spine.

  • lumbar curve: curve with apex between the first and fourth lumbar vertebrae.

  • lumbar kyphosis: reverse of the normal curve of the low back.

  • lumbosacral curve: a lateral curve with its aspect at or below the fifth lumbar vertebra.

  • neuromuscular scoliosis: scoliosis caused by a muscle or central nervous system disorder.

  • pelvic obliquity: slanting of the pelvis that can be caused by leg length inequality, contractures about the hips, a structural scoliosis, or as a combination of two or more of these disorders.

  • reversal of cervical lordosis: change in the normal curvature of the cervical spine as seen on lateral radiograph. This is usually a straightening of the normal lordotic curve or an actual reversal and is most commonly caused by muscle spasm, indicating cervical disk abnormality.

  • structural curve: a fixed lateral curve of the spinal column.

  • thoracic curve: a spinal curvature with its apex between the second and eleventh thoracic vertebrae.

  • thoracolumbar curve: a spinal curve with its apex at the first lumbar or twelfth thoracic curve.

  • segmental instability: abnormal response to applied loads characterized by motion in the motor segment beyond normal constraints.

  • spinal stenosis: general term denoting narrowing of the spinal canal in the lumbar area leading to nerve root compromise; term often used for developmental abnormality that leaves a narrow, bony canal. There are four subgroups of this condition:

    • achondroplastic stenosis: increased vertebral thickness, marked concavity of the vertebral body, and short pedicles.

    • combined stenosis: for congenital or developmental reasons, the midsagittal diameter is decreased .

    • constitutional stenosis: normal-stature individuals with congenital variance in vertebral structure leading to a narrow canal.

    • degenerative stenosis: gradual hypertrophy of the vertebral body margin, facet joints, and ligamentum flavum leading to stenosis.

  • temporomandibular joint (TMJ) syndrome: complex of symptoms often seen in cervical sprain conditions. Symptoms include clicking in the jaw on opening and closing the mouth, soreness in the jaw, headaches, buzzing sounds, changes in hearing, stiffness in the neck and shoulders, dizziness, and swallowing disorders. It is believed that much of the reason for this symptom complex relates to change of the mandibular posture and the resultant change in cervical posture, or vice versa; also called craniomandibular cervical syndrome.

  • thoracic outlet syndrome: mechanical problem related to the exit of arteries and nerves at the base of the neck leading down the arm, and can also involve the vein bringing blood back from the arm. Compression of these structures as they pass through a narrow space between the anterior scalene (scalenus anticus) muscle and first rib. Problem may be exacerbated by congenitally present additional cervical rib. An early sign is pain in the hand or shoulder. Arteries may be damaged in the process and cause an aneurysm in the area with possible break-off of clot from the aneurysm.

  • traction spur: bony excrescence appearing on the anterolateral surface of the vertebral body near but not at the body margin that arises as a result of disk degeneration.

  • transitional vertebra: vertebra whose structure features some of the characteristics of the two adjacent vertebra. A common example is the fifth lumbar vertebra that has partial sacral components.

  • wedging: deformity of vertebral body, caused by trauma or gradual collapse, resulting in wedge-shaped vertebra; can also occur congenitally.

Eponymic Spinal Disorders

  • Andersson lesion: lesions that have mixed patterns of disk plate sclerosis or bone absorption in some patients with ankylosing spondylitis.

  • Marie-Strümpell d.: inflammation of the spine, occurring as a rheumatoid-type disease in children.

  • Pott d.: tuberculosis of the spine, usually in the lower thoracic segments.

  • Scheuermann d.: inflammation of the anterior cartilage of the bodies of the lower thoracic and upper lumbar segments, causing pain in some older, growing children. There is more than 5 degrees of wedging of at least three adjacent vertebrae as seen on radiographs.

  • Schmorl nodes: developmental change resulting in inferior or superior extension of the intervertebral disk into the vertebral bodies.

Nerve Root Diseases of the Spine

The nerve roots in the spinal canal lie in close contact with the vertebrae and emerge through openings called foramina. In the neck, nerve root irritation may be localized at the place where it exits through the foramen, whereas in the lumbar spine, nerve root irritation usually occurs one level above the point of nerve exit.

Vertebrae and nerve roots of the spine are the same in number, except for the cervical spine. There are seven cervical vertebrae and eight cervical nerve roots (see Fig. 9-1 ). This occurs because the first cervical nerve exits between the skull and the first cervical vertebra. Therefore between C-7 and T-1 the eighth cervical nerve makes its exit. After this level, all nerves exit in conformance with the vertebra above the point of exit. When the examiner speaks of the nerve roots of the spine, it is recorded singularly as C1 or C2, whereas if the examiner is speaking of the intervertebral disk between the vertebrae, it is recorded in combination as C1-2 or C2-3. The vertebrae are recorded individually as C1 or L4.

This section is concerned with the local spinal processes and the wide range of neurologic diseases seen by an orthopaedist and especially by a neurosurgeon.

  • cauda equina syndrome: sufficient pressure on the nerves in the low back to produce multiple nerve root irritation and commonly loss of bowel and bladder control.

  • compression of nerve root: mechanical process resulting from a tumor, fracture, or herniated disk; the resultant irritation is called radiculitis if there is actual inflammation around the nerve. Pain from this type of disorder is called radicular pain. A common lay term for pressure on the nerve is pinched nerve, as sometimes used by examiners. After surgery and a normal healing process, the patient may still have some irritation of the nerve, which is often referred to as residual nerve root irritability. Sciatica and neuritis may be used in describing these disorders, but the terms are not discrete in that the irritation of the nerve is not necessarily from within the spinal canal.

  • dermatome: refers to the distribution of sensory nerves near the skin that are responsible for pain, tingling, and other sensations (or lack of). The afferent nerve fibers (leading to the spinal cord) and cutaneous branches arise from a single posterior spinal nerve root and contain sensory fibers. Loss of sensation in a dermatomal distribution may indicate damage to a nerve root that is caused by a disk prolapse.

    • referred pain: sclerotomic in distribution and felt distant from its origin (e.g., bursitis in the shoulder produces pain in the lateral arm, and sciaticlike leg pain can be referred from the low back area).

    • sclerotomal pain: more diffuse and ill-defined pain arising from voluntary muscles in spasm, also called myotomic distribution.

  • neurofibroma: fibrous tumor of a nerve, which may affect a nerve root and thus give the appearance of herniated disk disease.

  • radiculopathy: disease of the nerve roots in or near the spinal canal as a result of direct pressure from a disk or inflammation of the nerve roots caused by disk or spinal joint disease.

  • root sleeve fibrosis: scar tissue surrounding a nerve in the spinal canal or neural foramen.

  • sacral cyst: abnormality in the spinal fluid sac in the sacrum.

Disk Diseases

A disk is described as having a soft or fluidlike center called the nucleus pulposus and is surrounded by radial, circular, and longitudinal fibers that are firm, like gristle in meat. These intervertebral (IV) disks are situated between the vertebrae and act as shock absorbers. Any portion of the disk may herniate or extrude into the spinal canal, causing irritation and pressure on a nerve ( Fig. 9-5 ).

  • cartilage space narrowing: narrowing of any cartilage space; also called disk space narrowing .

  • degenerative disk disease: gradual or rapid deterioration of the chemical composition and physical properties of the disk space. This may involve a simple increase in the rigidity of the nuclear material to be more involved with cellular removal of abnormal tissue and an inflammatory response. If the ligaments around the disk space ossify, they are often referred to as bony spurs. Because the disk changes its physical properties, some clinicians describe the condition as a disorganized disk; that is, the normal property of a soft center surrounded by more rigid, fibrous tissue is disrupted. The inflammation and muscle spasm that may result over a prolonged period are often referred to as chronic cervical sprain, reflecting the abnormal stresses on the ligaments.

  • discitis: inflammation or infection of the disk space.

  • discogenic pain: back pain resulting from the disk itself. This pain is mechanical in nature and worse with sitting rather than standing. May be due to annular tears.

  • disk space infection: infection in the space normally occupied by an intervertebral disk.

  • herniated intervertebral disk (HID): outpouching of a disk.

  • herniated nucleus pulposus (HNP): fibrous extrusion of semifluid nucleus pulposus through a ruptured intervertebral disk; damage results from pressure on the spinal cord or nerve roots, causing pain and disability; also called herniated intervertebral disk (HID), ruptured disk, slipped disk. There are four recognized degrees of disk displacement:

    • extrusion: displaced material reaches the spinal canal through disrupted fibers of the annulus, but remains connected to the central disk material.

    • intraspongy nuclear herniation: bulge of the disk within the annulus fibrosus.

    • protrusion: displaced nuclear material causes a discrete bulge in the annulus, but no material escapes through the annular fibers.

    • sequestration: displaced material escapes as free fragments, which may migrate elsewhere.

  • intervertebral disk narrowing: narrowing of the space between any two vertebral bodies.

  • Naffziger syndrome: intervertebral disk disease, cervical rib, or some other disorder causes the scalene muscles to go into spasm, resulting in pressure on the major nerve plexus of the arm, causing pain in the neck, shoulder, arm, and hand; also called scalenus anticus syndrome.

  • sequestered disk herniation: portion of intervertebral disk that is completely extruded into spinal canal.

Dec 24, 2021 | Posted by in ORTHOPEDIC | Comments Off on The Spine
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