Spine anatomy (basic spine 2009)

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2. Introductory Spine Anatomy Course • IInnttrroodduuccttiioonn ttoo AAnnaattoommyy • BBaassiicc VVeerrtteebbrraall SSttrruuccttuurreess • JJooiinnttss aanndd LLiiggaammeennttss • MMuusscclleess aanndd NNeerrvveess • VVaassccuullaarr ssttrruuccttuurreess • AAddddiittiioonnaall oorrggaannss aanndd ssttrruuccttuurreess

3. OUR AIM • To be familiar with spine anatomy • To be spine-minded • To understand pathological spine diseases • To correlate symptoms and signs • To facilitate surgical skills

4. Anatomical Planes • Anatomical position • Anatomical planes • Coronal (Frontal) Plane divides the body into front and back sections • Sagittal Plane divides the body into left and right sections – Median - divides the body into equal left and right parts • Axial (Horizontal or Transverse) Plane - divides the body into upper and lower segments

5. A-P X-ray of a scoliotic spine in the coronal plane. The CORONAL PLANE, also called the FRONTAL PLANE, is a vertical cut that divides the body into front and back sections. Surgeons look at the coronal plane when they view an A-P (anterior-posterior) x-ray of the spine to evaluate scoliosis. Anatomical Planes

6. Lateral X-ray of a kyphotic spine in the sagittal plane. Anatomical Planes The SAGITTAL or MEDIAN PLANE is a vertical cut that divides the body into left and right sections. The sagittal view is seen by surgeons on a lateral x-ray of the spine.

7. Anatomical Planes CT Scan of a thoracic vertebra in the axial plane. The AXIAL or TRANSVERSE PLANE is a horizontal cut that divides the body into upper and lower sections. To best view the axial plane of the spine, surgeons will often obtain a CT scan with axial cuts.

8. Basic Terminology • Medial - towards the midline • Lateral - away from the midline • Proximal - closer to a point of reference (extremity) • Distal - farther from a reference point (extremity) • Superior - upper part or above a specific location • Inferior - lower part or below a specific location Lateral Medial Proximal (closer to) Distal Superior to Inferior (farther from) to Additional terms used in describing anatomical positions or locations:

9. • Cranial - the head or towards the head Cranial Caudal Anterior Posterior Dorsal Ventral • Caudal (tail) - the tail or towards the tail • Anterior - the front section or towards the front • Posterior - the back section or towards the back • Ventral - the front or anterior surface • Dorsal - the back or posterior surface Basic Terminology

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11. Your Turn: Anatomical Planes Name the Planes Axial Sagittal Corona?l ? ?

12. Your Turn: Basic Terminology Medial Proximal Distal Closer to the midline? Above? Superior to Inferior to Below ? Closer to? Further from? Away from the Lmaidtleinrea?l Name the Positions

13. Your Turn: Basic Terminology Caudal Name the Directions Anterior Posterior Dorsal Anterior surface? Towards the head? Towards the tail? Ventral Towards the front ? Towards the back? Posterior Surface? Cranial

14. FFuunnccttiioonnss ooff tthhee SSppiinnee In addition to the thirty-three vertebrae, the skull and the pelvis should be considered part of the spine. This is well noted in scoliotic patients when a full length x-ray of the spine with skull and pelvis is taken to evaluate the balance of the patient. The spine is responsible for:

15. Functions of the Spine • Protection of – spinal cord and nerve roots – internal organs

16. Functions of the Spine • Flexibility of motion in six degrees of freedom Flexion and Extension Left and Right Rotation Left and Right Side Bending

17. Functions of the Spine To achieve these functions, the spine must have: • Resistance to axial loading forces, accomplished by: –Kyphotic and lordotic sagittal plane curves –Increased mass of each vertebra from C1 to the sacrum •Elasticity accomplished by: –Alternating lordotic and kyphotic curves –Multiple MOTION SEGMENTS

18. The Motion Segment • The FUNCTIONAL UNIT of the spine • Composed of: – Two adjacent vertebrae – The intervertebral disc – Connecting ligaments – Two facet joints and capsules

20. Your Turn: Functions of the Spine The spine provides protection of the spinal ________, cord _________, and ___________. nerve roots internal organs The spine is flexible in ____six degrees of freedom. The ____________ motion segment is the functional unit of the spine.

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22. Regions of the Spine • Line of gravity Auricle of the ear Odontoid process (C2) Body of C7 Anterior to thoracic spine Posterior to L3 Femoral head

23. Regions of the Spine • Axial position of the spine by region Cervical - slightly anterior to the line of gravity Thoracic - significantly posterior Lumbar - middle of the body Sacrum - projects posteriorly

24. Sagittal Plane Curves In the coronal plane, the spine is straight. A lateral curve of the spine in the coronal plane is termed SCOLIOSIS. When viewed in the sagittal plane, the normal adult spine has four curves. There are two KYPHOTIC curves and two LORDOTIC curves. KYPHOSIS: A curvature in the sagittal plane with anterior concavity (concavity towards the front). The spine has a thoracic kyphosis and sacral kyphosis. LORDOSIS: A curvature in the sagittal plane with posterior concavity (concavity towards the back). The spine has a cervical lordosis and a lumbar lordosis.

25. Sagittal Plane Curves Cervical Lordosis 20°- 40° Thoracic Kyphosis 20°- 40° Lumbar Lordosis 30°- 50° Sacral Kyphosis

26. Sagittal Plane Curves • Primary Curves In a fetus, the spine has a continuous curvature of kyphosis like the letter “C.” This involves all spinal regions, but only the thoracic and sacral areas remain kyphotic throughout life. These kyphotic curves are considered to be PRIMARY CURVES.

27. Sagittal Plane Curves • Secondary Curves Lordotic curves are the spine’s response to weight bearing. When a child is two to three months of age and has sufficiently developed the posterior neck muscles, he becomes able to raise his head and keep it balanced over his shoulders. Correspondingly, the spine develops a lordotic curve in the cervical region.

28. Sagittal Plane Curves • Secondary Curves At about one year of age, as the child begins walking, he develops a lordosis in the lumbar spine. Cervical and lumbar lordoses are considered to be SECONDARY CURVES because they develop in response to weight bearing. The purpose of these secondary curves is to keep the spine balanced in the sagittal plane and reduce the workload of the posterior spinal musculature.

30. Your Turn: Regions of the Spine cervical lumbar The _______ and _______ regions of the spine have lordotic curves. thoracic sacral The _________ and ______ regions of the spine have kyphotic curves. A fetus has a C-shaped or kyphotic _p_rim__ar_y_ curve. Secondary curves develop in the __c_er_v_ic_a_l and __lu_m_b_a_r_ regions.

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32. Introductory Anatomical Overview

33. The Spine is a building • The vertebral bodies (Osseous spinal column) are the building blocks of the spine. • There are 7 cervical, 12 thoracic, 5 lumbar vertebral bodies and 5 fused sacral segments C1 (atlas) : anterior arch, posterior arch, and paired lateral masses * C2 (axis) : bony projection which articulate with C1 (odontoid process or dens) C3 ~ C7 : dorsolateral margin of the superior endplate (uncinate process)

34. Typical cervical, thoracic, and lumbar vertebra • Anterior body, • paired pedicles, articular pillars and laminae, and • a single dorsal midline spinous process • Spinous process – serve as a attachment point for the posterior ligamentous structures • Pedicle, articular pillars, and lamina - serve to protect the spinal cord and nerve roots • Transverse process in the mid-cervical : vertebral artery, osseous transverse foramina in the thoracic and lumbar spine : spinal column protect stabilize muscle

36. BBaassiicc VVeerrtteebbrraall SSttrruuccttuurreess Cervical Thoraci c Lumbar All vertebrae are formed according to the same basic structures, and the same nomenclature can be applied to all regions of the spine. Only the first and second cervical vertebrae are distinct in structure. This section reviews the basic structures common to all vertebrae. Previously we identified the four regions of the spine. Now we will examine the bony structures common to each region.

37. Types of Bone Tissue There are two types of bone tissue: • Cortical bone: dense, outer shell of the vertebra Haversian System Detail of Cortical Bone Detail of Cancellous Bone • Cancellous bone: inner, spongy bone

38. Vertebral Arches • Anterior Arch Composed of: – Vertebral body – Anterior 1/3 of the pedicles • Posterior Arch Comprised of: – Posterior 2/3 of the pedicles – Lamina – Processes Together the anterior arch and posterior arch create a large, closed space called the VERTEBRAL FORAMEN. When the individual vertebrae are stacked on each other, the vertebral foramen form the SPINAL CANAL, which contains and protects the spinal cord.

39. Vertebral Body Pedicle Lamina Superior Articular Process Spinous Process Transverse Process Vertebral Foramen Vertebral Structures

40. Vertebral Structures Superior Articular Process Inferior Articular Process Pars Zygapophyseal Joint (Facet Joint)

41. Vertebral Structures • Pedicle notches: The pedicles exit the upper one third of the vertebral body. They are notched slightly on the superior surface and deeply notched on the inferior surface. Slight Notch Deep Notch • Intervertebral foramen: When the vertebrae are stacked on one another the pedicle notches form the INTERVERTEBRAL FORAMEN through which the spinal nerve roots leave the spinal cord and exit to the body. Intervertebral Foramen

42. Transverse foramen, Intervertebral foramen, and Nerve roots Contents of Transverse foramen – vertebral artery, vertebral venous plexus, sympathetic chain Intervertebral foramen bounded by the pedicle, vertebral body, disc and superior articular process * Intervertebral Discs : thicker in the cervical and lumbar region and thicker anteriorly than posteriorly - axial loading absorb, flexibility - nucleus pulposus, annulus fibrosis, cartilaginous endplate Adamkiewicz artery : supply to the lower two-thirds of the spinal cord , enter the spinal canal via an intervertebral foramen -> transforaminal or periganglionic intervention damage

44. The Vertebral Ligaments Ligament – stability, flexion, extension, rotation - ALL, PLL, ligamentum flavum, interspinous ligament, supraspinous ligament - ALL : vertebral body and intervertebral disc - PLL : annulus fibrosis but does not contact the posterior vertebral margin - ligamentum flavum : laminar segment extend, spinal canal dorsolateral margin define - interspinous ligament, supraspinous lig. : spinous process

46. Intervertebral Disc • Intervertebral disc • Endplate – Cartilaginous layer – Bony layer • Apophyseal ring

47. The Intervertebral Disc • The disc is a shock absorber that is positioned between each end plate. • A normal disc is contains water and therefore is bright white in color on certain types of MRI images (T2 images). • nucleus pulposus : type II collagen, hyaluronic acid, glycoaminoglycan • annulus fibrosis : outer dense circumferential fibrous band and inner fibrocartilagenous layer • Injury to the disc can result in disc protrusions, tears in the outer fibers of the disc, reduction in disc height and pain.

49. Vertebral Body Pedicle Lamina Superior Articular Process Spinous Process Transverse Process Type of Cboannec?ellous Vertebral Foramen Name the Structures Type of Cboorntiec?al ? ? ? ? ? ? ? Your Turn

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51. • Cervical Regions of the Spine – Upper cervical: C1-C2 – Lower cervical: C3-C7 – The skull is often considered to be part of the spine and is then referred to as C0. • Thoracic: T1-T12 • Lumbar: L1- L5 • Sacrococcygeal: 9 fused vertebrae in the sacrum and coccyx. Labeling of the vertebrae

52. Upper Cervical Vertebrae, C1-C2 • Occipitocervical junction: – Occiput (C0) and Atlas (C1) – No disc • Atlantoaxial junction: – Atlas (C1) and Axis (C2) – No disc

53. The Atlas (C1) Transverse Process Transverse Foramen Anterior Tubercle Articular Facet for Dens Lateral Mass Posterior Lamina Tubercle Superior Articular Facet Superior View

54. The Axis (C2) Odontoid Process (Dens) Body Transverse Process Inferior Articular Facet Superior Articular Facet Lateral Mass Spinous Process Anterior View Posterior View

56. Typical cervical, thoracic, and lumbar vertebra • Anterior body, • paired pedicles, articular pillars and laminae, and • a single dorsal midline spinous process • Spinous process – serve as a attachment point for the posterior ligamentous structures • Pedicle, articular pillars, and lamina - serve to protect the spinal cord and nerve roots • Transverse process in the mid-cervical : vertebral artery, osseous transverse foramina in the thoracic and lumbar spine : spinal column protect stabilize muscle

58. Lower Cervical Vertebrae • C3 to C7 – May be referred to as the subaxial region – Disc at every level – Vertebral structures are similar

59. Lower Cervical Vertebrae C3 - C7 Transverse Sulcus for Body Process Spinal Nerve Lateral Mass Lamina Pedicle Transverse Foramen Superior Articular Facet Vertebral Foramen Bifid Spinous Process Axial View

60. Lower Cervical Vertebrae The vertebral bodies of the subaxial cervical spine have upward projections on the lateral margins called UNCINATE PROCESSES. These processes articulate with the level above to form the UNCOVERTEBRAL JOINT. These are also called JOINTS OF LUSCHKA. They are not capsular joints, but they do provide for some stability of the motion segments by their fibrous attachments. Uncinate Process Uncovertebral Joint (Joint of Luschka) C3 - C7 Anterior View Sulcus for Spinal Nerve

61. Vertebra Prominens (C7) Spinous Process Axial View C7 is sometimes referred to as the VERTEBRA PROMINENS because it has a longer and larger spinous process than the other cervical vertebrae. This spinous process is not usually bifid. Because it is so easily palpated at the base of the neck posteriorly, the vertebra prominens is used as an anatomic landmark to count the spinous processes of the thoracic vertebrae lying below.

62. Thoracic Vertebrae • Body - progressive increase in mass from T1 to T12 • Pedicles - small diameter • Laminae - vertical, with “roof tile” arrangement • Spinous processes - long, overlapping, projected downward • Intervertebral foramen - larger, less incidence of nerve compression

63. Thoracic Vertebrae, T1-T12 • Body - heart shaped when viewed superiorly. • Vertebral foramen - round • Pedicles - small in diameter • Spinous processes - long and projected downwards

64. Thoracic Vertebrae, T1-T12 • Articular processes Superior Articular Process Inferior Articular Process

65. Thoracic Vertebrae, T1-T12 • Costal and costotransverse facets On both sides of the vertebral body, there are smooth, rounded facet joints called the COSTOVERTEBRAL JOINTS. The ribs at the levels of T2-T9 articulate with two vertebrae at these synovial joints. The transverse process also attaches to the rib at the costotransverse articulation. The T1, T10, T11 and T12 vertebrae form joints with one rib only and have a single articulation on each side. Costal Facet Costotransverse Facet

66. Thoracic Vertebrae, T1-T12 C6 • The rib cage and spinous processes limit motion of the thoracic spine. This can put a strain on the cervical and lumbar vertebrae closest to the less mobile thoracic spine and makes them prone to injury. • Junctional vertebrae – C6 to T2 – T11 to L2 – adjacent regions are more prone to injury • Floating ribs at T11 and T12

67. Lumbar Vertebrae, L1-L5 • Body - L1 to L5 progressive increase in mass • Pedicles - longer and wider than thoracic; oval shaped • Spinous processes - horizontal, square shaped • Transverse processes - smaller than in thoracic region • Intervertebral foramen - large, but with increased incidence of nerve root compression

68. The Sacrum Sacral Horns (superior articular processes) Sacral Ala Inverted triangle shape Pedicles Dorsal Foramina Sacral Hiatus Coccyx Posterior View

69. Sacral Tilt 30°-60° Sacral Canal Coccyx Sacral Promontory Lateral View 1 2 3 4 5 Sacral Hiatus The Sacrum

70. Iliac Crests The ILIAC CRESTS are important in spine surgery because autogenous bone graft is often harvested from them. Both cortico-cancellous and cancellous bone graft can be obtained from either iliac crest. The posterior iliac crests are sometimes used to provide additional support and fixation for long rod constructs. This is generally referred to as sacropelvic fixation.

72. Your Turn: Name the Regions ? Cervical ? Thoracic ? ? Lumbar Sacral

73. Your Turn: Name the Vertebrae Atlas (superior vi?ew) Axis ? (povsietewr)ior Lower Cervical (anterior view) ?

74. Your Turn: Name the Vertebrae Lumbar Sacral Thoracic ? ? ?

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76. The Intervertebral Disc • The disc is a shock absorber that is positioned between each end plate. • A normal disc is contains water and therefore is bright white in color on certain types of MRI images (T2 images). • nucleus pulposus : type II collagen, hyaluronic acid, glycoaminoglycan • annulus fibrosis : outer dense circumferential fibrous band and inner fibrocartilagenous layer • Injury to the disc can result in disc protrusions, tears in the outer fibers of the disc, reduction in disc height and pain.

77. Intervertebral Disc • Fibrocartilaginous joint of the motion segment • Make up ¼ the length of the spinal column • Present at levels C2-C3 to L5- S1 • Allows compressive, tensile, and rotational motion • Largest avascular structures in the body

78. Intervertebral Disc • Annulus Fibrosus – Outer portion of the disc Lamellae – Made up of lamellae – Great tensile strength Annulus Fibrosus • Layers of collagen fibers • Arranged obliquely 30° • Reversed contiguous layers

79. Intervertebral Disc • Nucleus Pulposus Nucleus – Inner structure Pulposus – Gelatinous – High water content – Resists axial forces

80. Transverse foramen, Intervertebral foramen, and Nerve roots Contents of Transverse foramen – vertebral artery, vertebral venous plexus, sympathetic chain Intervertebral foramen bounded by the pedicle, vertebral body, disc and superior articular process * Intervertebral Discs : thicker in the cervical and lumbar region and thicker anteriorly than posteriorly - axial loading absorb, flexibility - nucleus pulposus, annulus fibrosis, cartilaginous endplate Adamkiewicz artery : supply to the lower two-thirds of the spinal cord , enter the spinal canal via an intervertebral foramen -> transforaminal or periganglionic intervention damage

82. • The spinal cord is a long thin bundle of nervous tissue that conducts information from the brain to the peripheral nervous system. • The spinal fluid bathes the spinal cord in fluid.

84. The intervertebral disc is composed of the ________________ and the annulus fibrosus __n_u_c_le_u_s_ p_u_l_p_o_s_u_s__. The layers of the annulus fibrosus are called the __l_a_m_e_l_la_e__ . The intervertebral disc is the largest __a_v_a_s_c_u_la_r___ structure in the body.

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87. Joints • atlanto-occipital : occipital condyle ~ lateral mass of C1 • Atlantoaxial : ventral dens ~ dorsal surface of C1 anterior arch • Uncovertebral : dorsolateral margin of the superior endplate of the C3~C7 • Costovertebra and Costotransverse : rib ~ vertebral body or transverse process of the thoracic spine • zygoapophyseal (facet) joints : the most prevalent joints , superior and inferior articular process *

88. Occipitocervical Joint Occipital Condyles Foramen Magnum articulate with C1 superior facets

89. Atlantoaxial Joint The articulation of the ATLANTOAXIAL JOINT between the atlas (C1) and the axis (C2) has a range of motion in the transverse plane for rotation. The DENS of C2 acts as a pivot point for the rotation of C1. The articulating surfaces of the two vertebrae form the C2 ZYGAPOPHYSEAL (FACET) JOINTS that allow flexion-extension, side bending, and rotational movements. Zygapophyseal joints C1 Dens

90. The Facet Joints The facet joints are also called ZYGAPOPHYSEAL JOINTS. The facet joints are formed by the articular processes of adjacent vertebrae. The inferior articular process of a vertebra articulates with the superior articular process of the vertebra below. The facets are synovial gliding joints because the articular surfaces glide over each other. They are capsular joints containing synovial fluid for lubrication.

91. The Facet Joints Facet joints are oriented in different planes depending on their anatomic location. The orientation of the facets controls the type and amount of joint motion. These hinges demonstrate the planes and angulation of the facet joints at each vertebral level.

92. Cervical Facet Joints 45° to the axial plane In the cervical region, the facet joints are flat and oriented 45° to the horizontal. This means that the cervical region has a significant range of motion in the six degrees of freedom.

93. Thoracic Facet Joints 60° to the axial plane 20° to the frontal plane In the thoracic region, the facet joints are flat and oriented 60° to the axial plane and 20° to the frontal plane with the inclination medially. Although the facets alone would allow for significant motion, the rib cage and spinous processes limit motion in extension, and rotation.

94. Lumbar Facet Joints 90° to the axial plane 45° to the frontal plane In the lumbar area, the facet joints are curved: the superior articular processes are concave, and the inferior articular processes are convex. They are oriented 90° to the axial plane and 45° to the frontal plane. Because of this orientation, the lumbar facets limit rotation but allow for flexion, extension, and side bending. When surgery is performed in the lumbar spine and the facets are destroyed, the potential for abnormal rotational movement increases.

95. Uncovertebral Joints Uncovertebral Joint The bony elevations on the superior lateral margins of the cervical vertebrae are called UNCINATE PROCESSES. These joints articulate with the inferior, lateral aspect of the vertebra above to form the UNCOVERTEBRAL JOINTS, also known as the JOINTS OF LUSCHKA. These are fibrous joints and do not have a capsule, but do provide stability, primarily in the M-L plane. The uncovertebral joints are not true joints but are often referred to as joints by spinal surgeons. Uncinate Process

96. Costovertebral Joints The T2-T9 thoracic vertebra have facets superiorly and inferiorly at the posterior aspect of the vertebral body that form the COSTOVERTEBRAL joints. Costovertebral joints Rib Costotransverse joints Axial View In the thoracic spine, the RIBS articulate with the vertebrae at both the body and the transverse processes. At all thoracic levels there is a facet where the rib articulates with the transverse process. These are called the COSTOTRANSVERSE joints. The T1 and T10-T12 vertebral bodies have only one costal facet. Rib

97. Lateral View Costovertebral joints Costotransverse joint Rib Costovertebral Joints

98. Lumbosacral Joint The LUMBOSACRAL JOINT is formed anteriorly by the wedge-shaped intervertebral disc Anterior View

99. Lumbosacral Joint and posteriorly by the L5-S1 facets. Two large articulating processes extend superiorly from S1 to meet with the inferior articulating processes of L5. L5 Posterior View The S1 superior articular processes are sometimes referred to as the SACRAL HORNS. These processes create facet joints that are oriented almost 90° in the coronal and axial planes and help to offset the significant shear forces caused by the 30° to 60° tilt of the superior endplate of S1. The lumbosacral joint is under great loading force because of the highly mobile lumbar segment joining with the rigid sacrum. Degenerative disease and spondylolisthesis often occur at the lumbosacral junction. sacrum

100. Sacroiliac Joint Sacroiliac Ligaments Sacrum Ilium The superior lateral surface on either side of the sacrum articulates with the inner aspects of the pelvis. This area forms the capsular, synovial SACROILIAC JOINT. The sacroiliac joint is also encompassed in a large amount of ligamentous and fibrous tissue for added stability. Therefore, the sacroiliac joint is both a capsular and a ligamentous joint. In some cases the sacroiliac joint is a hidden source of back pain.

102. Your Turn: Joints facet This joint is called the _____ joint or the _______________ zygapophyseal joint. This junction is called the _u_n_c_o_v_e_rt_e_b_ra_l__ joint. Bonus: Although not a true joint, it is sometimes called the joint of ________. Luschka The articulations of the ribs with the vertebrae are called the _c_o_st_o_v_e_rt_e_b_r_a_l _ joints.

103. Your Turn: Joints lumbosacral The ____________ joint is under a great loading force and has a high incidence of degenerative disease. The articulation of the sacrum with the pelvis is called the _s_a_c_ro_i_li_a_c__ joint.

104. LLiiggaammeennttss

105. Spinal Ligaments LIGAMENTS are bands or sheets of tough, fibrous tissue connecting two or more bones, cartilage bands, or other structures. They only become active when a joint is stressed to its maximum range of motion, protecting the joints from being hyperflexed or hyperextended. Ligaments are strongly anchored to the cortical bone of the vertebrae. Ligamentous structures are found in all regions of the spine. We will examine and identify the important ligaments in each region. Because of the significant ligamentous structures in the upper cervical region, we will examine that area separately.

106. Upper Cervical Ligaments The ligamentous structures of the upper cervical spine are extremely important in maintaining the stability of the spinal column and preventing neurologic injury. Ligamentous instability can result in significant subluxation of the C1-C2 complex, resulting in potentially catastrophic neurologic injury. The most important ligaments in the cervical area are discussed in this section.

107. Upper Cervical Ligaments Occipitoatlantal Ligament Complex Anterior occipitoatlantal ligament Posterior occipitoatlantal ligament Lateral occipitoatlantal ligament Anterior View

108. Upper Cervical Ligaments Atlantoaxial Ligament Complex Anterior view Posterior cutaway view Anterior atlantoaxial ligament Lateral atlantoaxial ligament capsule Posterior atlantoaxial ligament

109. Upper Cervical Ligaments Occipitoaxial Ligament Complex Alar ligaments (2) Apical ligament Posterior cutaway view Occipitoaxial ligament Posterior view

110. Upper Cervical Ligaments Cruciate Ligament Complex Superior longitudinal fascicle Inferior longitudinal fascicle Transverse ligament Posterior View

111. Upper/Lower Cervical Ligaments Superior longitudinal fascicle Anterior occipitoatlantal ligament Inferior longitudinal fascicle Posterior occipitoatlantal ligament Vertebral artery Lateral, Cross-sectional View Ligamentum nuchae Posterior atlantoaxial ligament Ligamentum flavum Transverse ligaments Anterior longitudinal ligament Posterior longitudinal ligament

112. Lower Cervical, Thoracic, and Lumbar Ligaments Anterior Longitudinal Ligament (ALL) The ANTERIOR LONGITUDINAL LIGAMENT (ALL) is composed of thick, longitudinally oriented fibers extending from the axis (C2) anteriorly to the sacrum. The ALL is broader at the level of each vertebral body than at the level of the discs where the fibers adhere to the annulus fibrosus. The ALL attaches to each vertebral body superiorly and inferiorly at the levels of the end plates.

113. Lower Cervical, Thoracic, and Lumbar Ligaments Intertransverse ligaments Costal ligaments The INTERTRANSVERSE LIGAMENTS extend from the inferior surface of the entire length of the transverse process to the superior surface of the adjacent transverse process. The COSTAL LIGAMENTS connect the heads of the ribs to the vertebrae.

114. Lower Cervical, Thoracic, and Lumbar Ligaments The POSTERIOR LONGITUDINAL LIGAMENT (PLL) is weaker than the ALL. Its fibers are also longitudinally oriented but less dense. It runs from the axis (C2) caudally to the sacrum. The PLL is narrow at the levels of the vertebrae, but the fibers extend laterally at the disc levels. These fibers may help to contain herniated disc material. Like the ALL, the PLL is attached to the vertebra at the superior and inferior margins, and to the annular fibers of the intervertebral disc. Posterior longitudinal ligament

115. Lower Cervical, Thoracic, and Interspinous ligament Lumbar Ligaments Ligamentum nuchae The INTERSPINOUS LIGAMENT connects each adjacent spinous process. The fibers extend from the base to the tip of each spinous process. In the cervical spine the interspinous ligament becomes part of the LIGAMENTUM NUCHAE, a fibro-membranous complex that extends from the interspinous ligament posteriorly and cranially to insert into the occiput.

116. Lower Cervical, Thoracic, and Lumbar Ligaments The SUPRASPINOUS LIGAMENT is a very strong band connecting the tips of contiguous spinous processes. It extends from C7 (vertebra prominens) to the sacrum. Supraspinous ligament Above C7 these fibers are Ligamentum nuchae part of the LIGAMENTUM NUCHAE.

117. Lower Cervical, Thoracic, and Lumbar Ligaments Ligamentum flavum The LIGAMENTUM FLAVUM, also called the YELLOW LIGAMENT, consists of elastic fibers oriented vertically that extend from the anterior inferior surface of the lamina above to the superior posterior surface of the lamina below. Unlike the ALL and PLL, the ligamentum flavum is not continuous. There is a small space in the midline between the right and the left fibers. The ligamentum flavum tends to thicken as it progresses down the spine, beginning at the axis (C2) and extending to the sacrum.

118. Lumbosacral Ligaments The ILIOLUMBAR LIGAMENTS extend from the transverse processes of L4 and L5 to the iliac crest. Iliolumbar ligaments Anterior View Posterior View

119. Lumbosacral Ligaments Lumbosacral ligaments Anterior View The LUMBOSACRAL LIGAMENT is a thick, fibrous band that extends from the anterior, inferior aspect of the transverse process of L5 to the lateral surface of the sacrum.

120. Sacroiliac Ligaments Short sacroiliac ligaments Posterior View The SACROILIAC LIGAMENTS are Long sacroiliac ligaments as follows: • short sacroiliac ligaments: composed of horizontal fibers extending from the sacrum to the posterior part of the iliac bone • long sacroiliac ligaments: composed of fibers extending vertically from the sacrum to the posterior superior iliac spine

122. Ligaments connect _b_o_n_e__ to _b_o_n_e__. Posterior longitudinal ligament (PLL) ? Anterior longitudinal ligament (ALL) ? Costal ligament ? Interspinous l?igament Ligamentum flavum? ?Supraspinous ligament Your Turn: Ligaments

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124. SSppiinnaall MMuusscclleess

125. Spinal Muscles Muscles related to the spine can be segmented into anterior and posterior groups. These groups can be further divided into superficial, middle, and deep layers. Muscles are attached to bone by tendons.

126. Anterior Spinal Muscle Groups Cervical The muscles most important to the anterior cervical spine are: • Longus capitis: originates at the occipital bone with insertions at the tranaverse processes of C3-C6 Longus capitis Longus colli Scalene • Longus colli: originates at the anterior portion of the vertebral bodies from C1-T3 with insertions at inferior vertebral bodies • Scalene: Connects the transverse processes of the cervical spine with the first two ribs

127. Anterior Spinal Muscle Groups Upper and Midthoracic Anteriorly, there are no muscles significant to spinal anatomy at these regions

128. Anterior Spinal Muscle Groups Lower Thoracic and Lumbar • Quadratus lumborum:from transverse processes of L1-L4 to iliac crest • Psoas Iliacum: Composed of: – Psoas major: from transverse processes and vertebral body of T2-L5 to the lesser trochanter of the femur – Iliacus: from the anterior margin of the iliac crest and the lesser trochanter of the femur

129. Posterior Spinal Muscle Groups The posterior back musculature can be divided into superficial, middle, and deep layers. These muscle groups form the TENSION BAND. The posterior muscle groups are often stripped from their bony attachments to the spine during surgical procedures. Compromise of the tension band may result in loss of sagittal plane balance.

130. Posterior Spinal Muscle Groups The superficial posterior muscles are collectively called the ERECTOR SPINAE, comprising three groups: Iliocostalis Longissimus Spinalis Erector Spinae

131. Posterior Spinal Muscle Groups Iliocostalis iliocostalis cervicis iliocostalis thoracis iliocostalis lumborum Longissimus longissimus capitis Spinalis spinalis capitis longissimus cervicis longissimus thoracis spinalis cervicis spinalis thoracis Detail of the ERECTOR SPINAE groups:

132. Posterior Spinal Muscle Groups The middle, or intermediate, muscle group of the spine is called the SEMISPINALIS GROUP: semispinalis capitis (cut) semispinalis cervicis (lies beneath layer shown) semispinalis thoracis

133. Posterior Spinal Muscle Groups The deep muscle layer consists of the following groups: Multifidus C1 to Sacrum (rotational movements) Intertransversarii attachments between spinous processes Rotatores (longus and brevis) attachments between transverse process and spinous process Rotatores cervices Rotatores thoracis Rotatores lumborum Levatores costae (longus and brevis) attachments between transverse process and ribs, C1-T11, and rib to rib

135. Your Turn: Muscles anterior Muscles can be segmented into _________ and _p_o_s_te_r_io_r__ groups. superficial middle Muscles can be subdivided into ___________, _________, and _________ deep layers. tension band The posterior muscle groups form the _______ ______ and provide sagittal plane balance.

136. NNeerrvvee SSttrruuccttuurreess

137. • The spinal cord is a long thin bundle of nervous tissue that conducts information from the brain to the peripheral nervous system. • The spinal fluid bathes the spinal cord in fluid.

138. Spinal Nerve Structures Spinal Cord • Contained in epidural space • Network of sensory and motor nerves • Firm, cord-like structure Foramen magnum • Extends from foramen magnum to L1 • Terminates at the conus medularis • The cauda equina begins below L1 • Filum terminale extends from conus medularis to the coccyx Conus medularis Cauda equina

139. Meninges The brain and spinal cord are covered by three layers of material called MENINGES. The main function of these layers is to protect and feed the delicate neurological structures. Dura mater Subdural space Arachnoid layer Subarachnoid space: filled with CSF Pia mater

140. Spinal Nerve Topography 31 pairs of spinal nerves • 8 cervical • 12 thoracic • 5 lumbar • 6 sacrococcygeal

141. Spinal Nerves Spinal cord Epidural space Dura mater and Arachnoid layers Subarachnoid space Dorsal root Ventral root Dorsal root ganglion Peripheral nerve

142. Autonomic Nervous System The AUTONOMIC NERVOUS SYSTEM (ANS) is a specialized system independent of voluntary control. The ANS controls glandular and cardiac function and smooth muscle such as that found in the digestive tract. All of the above organs are under involuntary control by the ANS. There are two components of the ANS: the sympathetic and the parasympathetic systems. The control centers of both systems are located outside the spinal cord in structures called GANGLIA.

143. Autonomic Nervous System The SYMPATHETIC NERVOUS SYSTEM consists of a series of ganglia extending from the skull to the coccyx, lying on each side of the vertebral bodies. These aligned ganglia look like a chain at each side of the spine and are often referred to as the sympathetic nerve chain. Injury to the sympathetic nerve chain in the lumbar spine may result in genitourinary problems for the patient. Each sympathetic ganglion has fibers that join to the adjacent spinal nerve, which creates redundancy within the system. The PARASYMPATHETIC NERVOUS SYSTEM (not shown) has ganglia located close to the organs they control.

145. Your Turn: Nerve Structures The spinal cord exits the skull through the __fo_ra_m_e_n__ _m_a_g_n_um___. At the ____ L1 level, the spinal cord terminates as the _____ conus medularis _______. Below L1, the spinal nerves are collectively known as the _____ cauda _____. equina The _____ filum _______ terminale extends to the coccyx and helps anchor the lower spinal cord.

146. Your Turn: Nerve Structures The layers of tissue covering the spinal cord are called the _m_e_n_in_ge_s__. ? ? Dura mater Subdural space Arachnoid layer Subarachnoid space: filled with CSF Pia mater ? ? ? Name the Structures

147. Your Turn: Nerve Structures Spinal cord Epidural space Subarachnoid space Dorsal root Ventral root Dorsal root ganglion Peripheral nerve ? ? ? ? ? ? ? Name the Structures

148. TThhiiss ccoonncclluuddeess MMuusscclleess aanndd NNeerrvveess TThhaannkk YYoouu!!

149. VVaassccuullaarr SSttrruuccttuurreess RReellaatteedd ttoo tthhee SSppiinnee

150. Vascular Structures Blood vessels are divided into two groups: ARTERIES are vessels carrying oxygenated blood from the heart to the internal organs and peripheral circulation. VEINS are vessels carrying deoxygenated blood back to the heart from the internal organs and peripheral circulation. There are two exceptions to the above definitions: the pulmonary artery carries deoxygenated blood from the heart to the lungs, where the blood is reoxygenated. The pulmonary veins carry oxygenated blood back to the heart from the lungs for circulation throughout the body. Together, the arteries and veins form a complex vascular tree with multiple branches reaching the smallest and farthest areas of the human body.

151. Arteries of the Cranial and Cervical Region Circle of Willis Vertebral arteries Basilar artery Internal carotid arteries

152. Arteries of the Cranial and Cervical Region Foramen lacerum Vertebral artery Carotid artery Anterior to the cervical vertebrae are the CAROTID ARTERIES, which ascend through the FORAMEN LACERUM and join with the vertebral arteries to form the CIRCLE OF WILLIS. Because of their proximity to the cervical vertebrae, they must always be considered during any anterior cervical procedure.

153. Arteries of the Thoracic and VertebrLalu mbosacral Regions artery Aortic arch Ascending aorta Descending aorta Thoracic segmental arteries Abdominal aorta Bifurcation of the aorta Lumbar segmental External iliac arteries artery (left & right) Internal iliac artery Femoral artery (left & right) (left & right)

154. Segmental Arteries At each vertebral level from T4 to the sacrum, a pair of SEGMENTAL ARTERIES branches posteriorly from the aorta to supply blood to the vertebral body, posterior elements, spinal cord, and costal structures. Spinal branch Intercostal artery Segmental arteries Aorta Anterior spinal artery Posterior branch Anastomoses

155. Veins of the Cervical and Thoracic Region The most important venous structures in the cervical spine are the internal and external JUGULAR VEINS. The internal jugular veins follow a path similar to the carotid arteries. As in other parts of the body, the veins form a network of vessels that provide compensatory circulation and a return of blood to the heart, even if there is a significant obstruction. The internal jugular veins should always be considered during any anterior cervical spine procedure. External jugular Anterior jugular Internal jugular

156. Veins of the Cervical and Thoracic Region The SUPERIOR VENA CAVA provides venous drainage of the cervical and upper thoracic spine. The segmental vessels from these regions drain into the superior vena cava. Superior vena cava

157. Veins of the Thoracic and Lumbar Internal Region jugular Superior Azygos vena cava vein Thoracic segmental veins Hemiazygos vein Lumbar segmental veins Inferior vena cava Common iliac vein (left and right)

158. Batson’s Plexus The AZYGOS SYSTEM is a large network of veins draining nutrient-rich blood from the intestines and other abdominal organs back to the heart. At some levels, the segmental veins drain into the azygos vein located on the right side of the abdomen, or into the hemiazygos vein located on the left side. This system of veins presents a particular challenge to the spine surgeon. The azygos system also communicates with a valveless venous network known as BATSON’S PLEXUS. When the vena cava is partially or totally occluded, Batson’s plexus provides an alternate route for blood return to the heart. Batson’s plexus

160. Your Turn: Arteries Vertebral artery Aortic arch Ascending aorta Descending ? ? aorta Thoracic segmental arteries ? ? Name the Arteries Abdominal aorta ? ? Bifurcation of the aorta Lumbar ? segmental ? External iliac arteries artery Internal ? Femoral artery iliac artery ? ?

161. Internal jugular Your Turn: Veins Superior ? Azygos ? vena cava vein Thoracic segmental veins Hemiazygos Name the Veins vein Lumbar segmental veins Inferior vena cava Common iliac veins (left and right) ? ? ? ? ? ?

162. AAnnaattoommiiccaall SSttrruuccttuurreess RReellaatteedd ttoo tthhee SSppiinnee This section discusses some of the additional organs and structures related to surgery of the spine. Vascular structures are pointed out for reference purposes. These structures can be studied by region.

163. Anatomical Structures Related to the Cervical Spine Internal carotid artery Jugular vein Common carotid artery Subclavian artery Aorta Posterior View Hyoid bone Epiglottis Thyroid gland Parathyroid glands Trachea Left vagus nerve Left recurrent laryngeal nerve Superior vena cava

164. Anatomical Structures Related to the Thoracic Spine Vertebral artery Trachea Esophagus Aortic arch Heart (in pericardium) Diaphragm Descending aorta

165. Abdominopelvic Structures Related to the Spine Superior vena cava Accessory hemiazygos vein Hemiazygos vein Azygos vein Inferior vena cava Portal vein Diaphragm Stomach Spleen Liver (cross sectioned)

166. Abdominopelvic Structures Related to the Spine Diaphragm Liver Esophagus Stomach Pancreas Parietal peritoneum (anterior abdominal wall) Abdominal aorta Small intestine Urinary bladder Rectum

168. Your Turn: Related Structures Vertebral artery Trachea Esophagus Aortic arch Name the Structures Heart (in pericardium) Diaphragm Descending aorta ? ? ? ? ? ? ?

169. Your Turn: Related Structures Superior vena cava Hemiazygos vein Azygos vein Inferior vena cava Portal vein Diaphragm Stomach Spleen Liver (cross sectioned) ? ? ? ? ? ? ? ? ? Name the Structures

170. Your Turn: Related Structures ? ? ? Diaphragm Liver Esophagus ? ? Stomach Pancreas ? ? Parietal peritoneum (anterior abdominal wall) Abdominal aorta Small intestine Name the Structures Urinary bladder Rectum ? ? ?

171. This concludes the Anatomy sseeccttiioonn ooff tthhiiss CCoouurrssee.. NNeexxtt ttoo bbeeggiinn tthhee PPaatthhoollooggyy sseeccttiioonn.. TThhaannkk YYoouu!!

Spine anatomy (basic spine 2009)

Spine anatomy (basic spine 2009)

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