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7.2 The Vertebral Column General Characteristics Extends from skull to pelvis Also called spine or spinal column Functions to transmit weight of trunk to lower limbs, surround and protect spinal cord, provide attachment points for ribs and muscles Flexible curved structure contains 26 irregular bones called vertebrae in five major regions © 2016 Pearson Education, Inc.

General Characteristics (cont.) Regions and curvatures Regions: ~28 long vertebral column broken into five major regions: Cervical: consists of 7 vertebrae Thoracic: 12 vertebrae Lumbar: 5 vertebrae Remember meal times: 7 am, 12 noon, and 5 pm Sacrum: one bone, formed from fusion of several bones, articulates with hip Coccyx: also fused bones that form terminus of column © 2016 Pearson Education, Inc.

General Characteristics (cont.) Curvatures: four main curves in the column help to increase resilience and flexibility of spine Cervical and lumbar curvatures Concave posteriorly Thoracic and sacral curvatures Convex posteriorly © 2016 Pearson Education, Inc.

Figure 7.16 The vertebral column. 2 3 Cervical curvature (concave) 7 vertebrae, C1: C7 4 5 6 7 T1 Spinous process 2 3 Transverse processes 4 5 6 Thoracic curvature (convex) 12 vertebrae, T1: T12 7 8 9 Intervertebral discs 10 1 1 Intervertebral foramen 12 L1 2 Lumbar curvature (concave) 5 vertebrae, L1: L5 3 4 5 Sacral curvature (convex) 5 fused vertebrae sacrum Coccyx 4 fused vertebrae Anterior view Right lateral view © 2016 Pearson Education, Inc.

General Characteristics (cont.) Ligaments: along with trunk muscles, help support vertebral column Anterior and posterior longitudinal ligaments: continuous bands from neck to sacrum that run down front and back of spine Support and prevent hyperextension (backward) or hyperflexion (forward) bending Ligamentum flavum: connects adjacent vertebrae Short ligaments: connect each vertebra to those above and below © 2016 Pearson Education, Inc.

Figure 7.17a Ligaments and fibrocartilage discs uniting the vertebrae. Intervertebral disc Supraspinous ligament Transverse process Anterior longitudinal ligament Sectioned spinous process Intervertebral foramen Posterior longitudinal ligament Ligamentum flavum Interspinous ligament Anulus fibrosus Nucleus pulposus Inferior articular process Sectioned body of vertebra Median section of three vertebrae © 2016 Pearson Education, Inc.

Figure 7.17b Ligaments and fibrocartilage discs uniting the vertebrae. Posterior longitudinal ligament Anterior longitudinal ligament Body of a vertebra Intervertebral disc Anterior view of part of the spinal column © 2016 Pearson Education, Inc.

General Characteristics (cont.) Intervertebral discs Cushionlike pad sandwiched between vertebrae that act as shock absorbers Composed of two parts Nucleus pulposus Inner gelatinous nucleus Gives disc its elasticity and compressibility Anulus fibrosus Outer collar composed of collagen and fibrocartilage Limits expansion of nucleus pulposus when compressed © 2016 Pearson Education, Inc.

Figure 7.17c Ligaments and fibrocartilage discs uniting the vertebrae. Vertebral spinous process (posterior aspect of vertebra) Spinal cord Spinal nerve root Transverse process Herniated portion of disc Anulus fibrosus of disc Nucleus pulposus of disc Superior view of a herniated intervertebral disc © 2016 Pearson Education, Inc.

Figure 7.17d Ligaments and fibrocartilage discs uniting the vertebrae. Nucleus pulposus of intact disc Herniated nucleus pulposus MRI of lumbar region of vertebral column in sagittal section showing herniated disc © 2016 Pearson Education, Inc.

Clinical – Homeostatic Imbalance 7.2 Severe physical trauma to spine may result in one or more herniated (prolapsed) discs Usually involves rupture of anulus fibrosus, resulting in protrusion of nucleus pulposus, which can press on spinal cord or nerves, causing numbness or excruciating pain Treatment: exercise, massage, heat, painkillers, or surgical intervention involving bone grafting to fuse adjoining vertebrae Percutaneous laser disc decompression vaporizes part of disc; tears can be sealed electrothermally © 2016 Pearson Education, Inc.

Clinical – Homeostatic Imbalance 7.2 Abnormal spinal curvatures can be congenital or result from disease, poor posture, or unequal pull of muscles on spine Scoliosis: abnormal lateral rotation of spine, most often in thoracic region, which may lead to breathing difficulties Kyphosis (hunchback): is abnormal dorsal thoracic curvature common in people with osteoporosis, tuberculosis of spine, rickets, or osteomalacia Lordosis (swayback): is accentuated lumbar curvature that can result from disease but is also seen in men with pot bellies and in pregnant women © 2016 Pearson Education, Inc.

Figure 7.18 Abnormal spinal curvatures. Scoliosis Kyphosis Lordosis © 2016 Pearson Education, Inc.

General Structure of Vertebrae All have common structural pattern consisting of: Body (centrum), the anterior weight-bearing region Vertebral arch composed of: Two pedicles: short pillars form sides of arch Two laminae: fused, flattened plates form posterior arch Vertebral foramen: enclosure formed by body and vertebral arch coming together Vertebral canal: series of vertebral foramina Intervertebral foramina: lateral openings between vertebrae for passage of spinal nerves © 2016 Pearson Education, Inc.

Figure 7.19 Typical vertebral structures. Posterior Spinous process Transverse process Superior articular facet and process Vertebral arch • Lamina • Pedicle Vertebral foramen Body Anterior © 2016 Pearson Education, Inc.

General Structure of Vertebrae (cont.) Vertebrae have seven processes: Spinous process: projects posteriorly Transverse processes (2): project laterally Superior articular processes (2): protrude superiorly Inferior articular processes (2): protrude inferiorly © 2016 Pearson Education, Inc.

Animation: Rotatable Spine (Horizontal) © 2016 Pearson Education, Inc.

Animation: Rotatable Spine (Vertical) © 2016 Pearson Education, Inc.

Regional Vertebral Characteristics Cervical vertebrae C1 to C7: smallest, lightest vertebrae C3 to C7 share following features: Oval-shaped body Exception: C7 spinous processes are split (bifid) Large, triangular vertebral foramen Transverse foramen found in each transverse process for artery passageways C7 is vertebra prominens; large and can be felt through skin, so used as a landmark © 2016 Pearson Education, Inc.

Table 7.2-1 Regional Characteristics of Cervical, Thoracic, and Lumbar Vertebrae © 2016 Pearson Education, Inc.

Table 7.2-2 Regional Characteristics of Cervical, Thoracic, and Lumbar Vertebrae (continued) © 2016 Pearson Education, Inc.

Table 7.2-3 Regional Characteristics of Cervical, Thoracic, and Lumbar Vertebrae (continued) © 2016 Pearson Education, Inc.

Figure 7.21a Posterolateral views of articulated vertebrae. Dens of axis Transverse ligament of atlas C1 (atlas) C2 (axis) C3 Inferior articular process Bifid spinous process Transverse processes C7 (vertebra prominens) Cervical vertebrae © 2016 Pearson Education, Inc.

Regional Vertebral Characteristics (cont.) Cervical vertebrae (cont.) C1 (atlas) and C2 (axis) have unique features Atlas (C1) No body or spinous process Consists of anterior and posterior arches, and two lateral masses Superior surfaces of lateral masses articulate with occipital condyles Occipital condyles “carry” skull Movement for nodding head “Yes” © 2016 Pearson Education, Inc.

Figure 7.20a The first and second cervical vertebrae. Posterior Posterior tubercle Posterior arch Transverse foramen Lateral masses Superior articular facet Anterior arch Anterior tubercle Superior view of atlas (C1) © 2016 Pearson Education, Inc.

Figure 7.20b The first and second cervical vertebrae. Posterior Posterior tubercle Posterior arch Inferior articular facet Transverse process Lateral masses Transverse foramen Anterior arch Facet for dens Anterior tubercle Inferior view of atlas (C1) © 2016 Pearson Education, Inc.

Regional Vertebral Characteristics (cont.) Axis (C2) Has body and processes like other vertebrae Major feature is knoblike dens that projects superiorly into anterior arch of atlas Dens is the “missing” body of atlas Dens is a pivot for rotation of atlas Movement allows side to side rotation for saying “No” © 2016 Pearson Education, Inc.

Figure 7.20c The first and second cervical vertebrae. Posterior C2 Spinous process Inferior articular process Lamina Pedicle Superior articular facet Transverse process Dens Body Superior view of axis (C2) © 2016 Pearson Education, Inc.

Figure 7.20d The first and second cervical vertebrae. Posterior Transverse foramen in transverse process Spinous process Superior articular facet Dens Body Photo of axis (C2), superior view © 2016 Pearson Education, Inc.

Figure 7.21a Posterolateral views of articulated vertebrae. Dens of axis Transverse ligament of atlas C1 (atlas) C2 (axis) C3 Inferior articular process Bifid spinous process Transverse processes C7 (vertebra prominens) Cervical vertebrae © 2016 Pearson Education, Inc.

Regional Vertebral Characteristics (cont.) Thoracic vertebrae T1 to T12 increase in size and articulate with ribs Unique characteristics: Body is heart shaped with two small demifacets that articulate with ribs T10 to T12 have only single facet, not two Vertebral foramen is circular Long, sharp spinous process points inferiorly Transverse processes have transverse costal facets that articulate with ribs (except T11, T12) Location of articular facets allows rotation of this area of spine © 2016 Pearson Education, Inc.

Table 7.2-1 Regional Characteristics of Cervical, Thoracic, and Lumbar Vertebrae © 2016 Pearson Education, Inc.

Table 7.2-2 Regional Characteristics of Cervical, Thoracic, and Lumbar Vertebrae (continued) © 2016 Pearson Education, Inc.

Table 7.2-3 Regional Characteristics of Cervical, Thoracic, and Lumbar Vertebrae (continued) © 2016 Pearson Education, Inc.

Figure 7.21b Posterolateral views of articulated vertebrae. Superior articular process Transverse process Transverse costal facet (for tubercle of rib) Intervertebral disc Body Inferior costal facet (for head of rib) Spinous process Inferior articular process Thoracic vertebrae © 2016 Pearson Education, Inc.

Regional Vertebral Characteristics (cont.) Lumbar vertebrae L1 to L5 “small of back”; receives most stress, so bodies are massive Other characteristics: Short, thick pedicles and laminae Flat, hatchet-shaped spinous processes point posteriorly Vertebral foramen is triangular Orientation of articular facets locks lumbar vertebrae together to prevent rotation © 2016 Pearson Education, Inc.

Table 7.2-1 Regional Characteristics of Cervical, Thoracic, and Lumbar Vertebrae © 2016 Pearson Education, Inc.

Table 7.2-2 Regional Characteristics of Cervical, Thoracic, and Lumbar Vertebrae (continued) © 2016 Pearson Education, Inc.

Table 7.2-3 Regional Characteristics of Cervical, Thoracic, and Lumbar Vertebrae (continued) © 2016 Pearson Education, Inc.

Figure 7.21c Posterolateral views of articulated vertebrae. Superior articular process Transverse process Body Intervertebral disc Inferior articular process Spinous process Lumbar vertebrae © 2016 Pearson Education, Inc.

Regional Vertebral Characteristics (cont.) Sacrum: triangular bone shapes posterior wall of pelvis; made from five fused vertebrae (S1–S5) Superior articular process articulates with L5 Articulates inferiorly with coccyx and laterally with hip bones via its auricular surfaces, forming sacroiliac joints Sacral promontory: anterosuperior margin Transverse ridges mark lines of fusion Anterior sacral foramina: lie at lateral ends of ridges; act as openings for nerves and vessels Alae: winglike expansions © 2016 Pearson Education, Inc.

Regional Vertebral Characteristics (cont.) Sacrum (cont.) Median sacral crest: roughened bumps on posterior midline and lateral sacral crest; roughened area seen laterally on posterior side Posterior sacral foramina: large openings for sacral spinal nerves Sacral canal: continuation of vertebral canal Sacral hiatus: large opening at end of canal Coccyx: tailbone formed from three to five fused vertebrae; articulates superiorly with sacrum Very little function © 2016 Pearson Education, Inc.

Figure 7.22a The sacrum and coccyx. Sacral promontory Ala Body of first sacral vertebra Transverse ridges (sites of vertebral fusion) Anterior sacral foramina Apex Coccyx Anterior view © 2016 Pearson Education, Inc.

Figure 7.22b The sacrum and coccyx. Facet of superior articular process Body Sacral canal Ala Auricular surface Lateral sacral crest Median sacral crest Posterior sacral foramina Sacral hiatus Coccyx Posterior view © 2016 Pearson Education, Inc.

7.3 Thoracic Cage Composed of: Functions Thoracic vertebrae posteriorly Sternum and costal cartilages anteriorly Ribs laterally Functions Protects vital organs of thoracic cavity Supports shoulder girdles and upper limbs Provides attachment sites for muscles of neck, back, chest, and shoulders © 2016 Pearson Education, Inc.

Figure 7.23a The thoracic cage. Jugular notch Clavicular notch Sternum • Manubrium • Sternal angle • Body • Xiphisternal joint True ribs (1–7) • Xiphoid process False ribs (8–12) Intercostal spaces L1 Vertebra Costal cartilage Floating ribs (11, 12) Costal margin Skeleton of the thoracic cage, anterior view © 2016 Pearson Education, Inc.

Sternum Also called the breastbone; consists of three fused bones: Manubrium: superior portion that articulates with clavicular notches and ribs 1 and 2 Body: midportion that articulates with costal cartilages of ribs 2 through 7 Xiphoid process: inferior end that is site of muscle attachment Not ossified until ~age 40 © 2016 Pearson Education, Inc.

Sternum (cont.) Sternum has three important anatomical landmarks: Jugular notch Central indentation in superior border of manubrium Sternal angle Horizontal ridge across front of sternum Xiphisternal joint Point where sternal body and xiphoid process fuse © 2016 Pearson Education, Inc.

Figure 7.23b The thoracic cage. Jugular notch T3 Sternal angle T4 Heart Xiphisternal joint T9 Midsagittal section through the thorax, showing the relationship of surface anatomical landmarks of the thorax to the vertebral column © 2016 Pearson Education, Inc.

Clinical – Homeostatic Imbalance 7.4 Xiphoid process projects posteriorly in some people A blow to the chest (chest trauma) at the level of the xiphoid process can push process into underlying liver or heart Can cause massive hemorrhaging © 2016 Pearson Education, Inc.

Ribs 12 pairs form sides of thoracic cage All attach posteriorly to bodies and transverse processes of thoracic vertebrae True (vertebrosternal) ribs (pairs 1–7) Attach directly to sternum by individual costal cartilages False (vertebrochondral) ribs (pairs 8–10) Attach indirectly to sternum by joining costal cartilage of rib above Vertebral (floating) ribs (pairs 11–12) No attachment to sternum © 2016 Pearson Education, Inc.

Figure 7.23a The thoracic cage. Jugular notch Clavicular notch Sternum • Manubrium • Sternal angle • Body • Xiphisternal joint True ribs (1–7) • Xiphoid process False ribs (8–12) Intercostal spaces L1 Vertebra Costal cartilage Floating ribs (11, 12) Costal margin Skeleton of the thoracic cage, anterior view © 2016 Pearson Education, Inc.

Ribs (cont.) Main parts of rib: Shaft: flat bone that makes up most of rib Costal groove: houses nerves and vessels Head (posterior end) Articulates with facets (demifacets) on bodies of two adjacent vertebrae Neck: constricted portion beyond head Tubercle: knoblike structure lateral to neck Articulates posteriorly with transverse costal facet of same-numbered thoracic vertebra © 2016 Pearson Education, Inc.

Transverse costal facet (for tubercle of rib) Superior costal facet Figure 7.24a Ribs. Transverse costal facet (for tubercle of rib) Superior costal facet (for head of rib) Angle of rib Body of vertebra Head of rib Intervertebral disc Neck of rib Tubercle of rib Shaft Sternum Cross- section of rib Costal groove Costal cartilage Vertebral and sternal articulations of a typical true rib © 2016 Pearson Education, Inc.

Superior view of the articulation between a rib and a Figure 7.24b Ribs. Articular facet on tubercle of rib Spinous process Shaft Transverse costal facet (for tubercle of rib) Ligaments Neck of rib Body of thoracic vertebra Head of rib Superior costal facet (for head of rib) Superior view of the articulation between a rib and a thoracic vertebra © 2016 Pearson Education, Inc.

Facets for articulation with vertebrae Articular facet on tubercle Figure 7.24c Ribs. Facets for articulation with vertebrae Articular facet on tubercle Shaft Head Neck Junction with costal cartilage Costal groove Angle of rib A typical rib (rib 6, right), posterior view © 2016 Pearson Education, Inc.