The document provides an overview of spinal anatomy including: 1) It describes the coronal, sagittal, and axial planes used to view the spine on imaging and their anatomical divisions. 2) The basic structures and functions of vertebrae are outlined including protection of the spinal cord, flexibility, and load distribution. 3) Ligaments, joints, vasculature and innervation of the spine are summarized at different regions from cervical to lumbar.

1. ANATOMY OF SPINE Dr Pankaj N Surange MBBS, MD, FIPP Interventional Pain and Spine specialist

2. Anatomical Planes 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. Physicians look at the coronal plane when they view an A-P (anterior-posterior) x-ray of the spine to evaluate scoliosis.

3. Anatomical Planes Lateral X-ray of a kyphotic spine in the sagittal plane. 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.

4. 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.

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

14. Basic Vertebral Structures Cervical Thoracic Lumbar

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

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

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

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

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

24. Lower Cervical Vertebrae C3 - C7 Sulcus for Spinal Nerve Uncinate Process Uncovertebral Joint (Joint of Luschka) Anterior View 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 .

25. Vertebra Prominens (C7) Spinous Process Axial View C7 is 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.

30. The Sacrum Sacral Horns Sacral Ala Pedicles Dorsal Foramina Sacral Hiatus Coccyx Posterior View Inverted triangle shape

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

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

38. Atlantoaxial Joint C1 C2 Dens Zygapophyseal joints 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 ZYGAPOPHYSEAL (FACET) JOINTS that allow flexion-extension, side bending, and rotational movements.

39. The Facet Joints 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. These are synovial gliding joints Facet joints are oriented in different planes depending on their anatomic location.

40. Uncovertebral Joints Uncovertebral Joint The bony elevations on the superior lateral margins of the cervical vertebrae are called UNCINATE PROCESSES . The uncovertebral joints are not true joints 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 Uncinate Process

41. 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

42. Costovertebral Joints Lateral View Costovertebral joints Costotransverse joint Rib

43. 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 . In some cases the sacroiliac joint is a hidden source of back pain .

47. 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.

49. Lower Cervical, Thoracic, and Lumbar Ligaments Interspinous ligament Ligamentum nuchae The INTERSPINOUS LIGAMENT connects each adjacent spinous process. In the cervical spine the interspinous ligament becomes part of the LIGAMENTUM NUCHAE , that extends cranially to insert into the occiput.

51. Lower Cervical, Thoracic, and Lumbar Ligaments Ligamentum flavum 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. The ligamentum flavum tends to thicken as it progresses down the spine, beginning at the axis (C2) and extending to the sacrum.

53. Lumbosacral Ligaments Anterior View Lumbosacral ligaments 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.

58. Arteries of the Cranial and Cervical Region Foramen lacerum Vertebral artery Carotid artery Two VERTEBRAL ARTERIES , one located on each side the cervical vertebrae. These arteries are branches of the right and left subclavian vs. that exit from aorta. They ascend through the transverse foramen of C6 through C1,entering the skull through the foramen magnum where they join together to form the BASILAR 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 .

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

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

62. 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. They should always be considered during any anterior cervical spine procedure. External jugular Anterior jugular Internal jugular

63. Veins of the Thoracic and Lumbar Region Internal jugular Superior vena cava Azygos vein Thoracic segmental veins Hemiazygos vein Lumbar segmental veins Inferior vena cava Common iliac veins

64. Batson’s Plexus The AZYGOS SYSTEM is a large network of veins draining blood from the intestines and other abdominal organs back to the heart. 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. 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. The vessels of Batson’s plexus may be referred to as epidural veins Batson’s plexus

65. Batson’s Plexus Because of the azygos system, patient positioning is very important in posterior lumbar spine surgery. The patient’s abdomen should always hang free and without abdominal pressure. An increase in pressure will diminish flow through the azygos system and the vena cava. This results in an increase of venous flow into Batson’s plexus with a corresponding increase of blood loss . Batson’s plexus

67. Meninges Dura mater Subdural space Arachnoid layer Subarachnoid space: filled with CSF Pia mater Within the spinal canal, the spinal cord is surrounded by the EPIDURAL SPACE, filled with fatty tissue, veins, and arteries. The fatty tissue acts as a shock absorber. The spinal cord is covered by MENINGES which has three layers.

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

70. Autonomic Nervous System Independent of voluntary control. Controls glandular and cardiac function and smooth muscle such as that found in the digestive tract. There are two components: sympathetic parasympathetic The control centers of both systems are located outside the spinal cord in structures called GANGLIA .

71. 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. The PARASYMPATHETIC NERVOUS SYSTEM has ganglia located close to the organs they control.

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