Chapter 7 Part B The Skeleton Annie LeibovitzContact

7. 2 The Vertebral Column General Characteristics • Extends from skull to pelvis •

7. 2 The Vertebral Column General Characteristics • Functions: – 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: 1. Cervical: consists of 7 vertebrae 2. Thoracic: 12 vertebrae 3. Lumbar: 5 vertebrae – Remember meal times: 7 am, 12 noon, and 5 pm 4. Sacrum: one bone, formed from fusion of several bones 5. 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. C 1 2 3 4 5 6 7 Cervical curvature (concave) 7 vertebrae, C 1: C 7 T 1 Spinous process 2 3 Transverse processes 4 5 6 7 8 Thoracic curvature (convex) 12 vertebrae, T 1: T 12 9 10 11 Intervertebral discs Intervertebral foramen 12 L 1 2 3 4 Lumbar curvature (concave) 5 vertebrae, L 1: L 5 5 Sacral curvature (convex) 5 fused vertebrae sacrum Coccyx 4 fused vertebrae © 2016 Pearson Education, Inc. Anterior view Right lateral view

Figure 7. 17 a Ligaments and fibrocartilage discs uniting the vertebrae. Supraspinous ligament Transverse process Sectioned spinous process Intervertebral disc Anterior longitudinal ligament Intervertebral foramen Ligamentum flavum Posterior longitudinal ligament Interspinous ligament Anulus fibrosus Inferior articular process Median section of three vertebrae © 2016 Pearson Education, Inc. Nucleus pulposus Sectioned body of vertebra

Figure 7. 17 b 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

Figure 7. 17 c 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. 17 d 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 © 2016 Pearson Education, Inc. Kyphosis Lordosis

General Structure of Vertebrae • All have common structural pattern consisting of: – Body (centrum), the anterior weight-bearing region – Vertebral arch composed of: – 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 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.

Regional Vertebral Characteristics • Cervical vertebrae – C 1 to C 7: smallest, lightest vertebrae – C 3 to C 7 share following features: • • Oval-shaped body Exception: C 7 spinous processes are split (bifid) Large, triangular vertebral foramen Transverse foramen found in each transverse process for artery passageways • C 7 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

Table 7. 2 -2 Regional Characteristics of Cervical, Thoracic, and Lumbar Vertebrae (continued) ©

Table 7. 2 -3 Regional Characteristics of Cervical, Thoracic, and Lumbar Vertebrae (continued) ©

Figure 7. 21 a Posterolateral views of articulated vertebrae. Dens of axis Transverse ligament of atlas C 1 (atlas) C 2 (axis) C 3 Inferior articular process Bifid spinous process Transverse processes C 7 (vertebra prominens) Cervical vertebrae © 2016 Pearson Education, Inc.

Regional Vertebral Characteristics (cont. ) • Cervical vertebrae (cont. ) – C 1 (atlas) and C 2 (axis) have unique features – Atlas (C 1) • 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. 20 a The first and second cervical vertebrae. Posterior C 1 Posterior tubercle Posterior arch Transverse foramen Lateral masses Anterior arch Anterior tubercle Superior view of atlas (C 1) © 2016 Pearson Education, Inc. Superior articular facet

Figure 7. 20 b The first and second cervical vertebrae. Posterior tubercle Posterior arch Inferior articular facet Transverse process Lateral masses Transverse foramen Facet for dens Inferior view of atlas (C 1) © 2016 Pearson Education, Inc. Anterior arch Anterior tubercle

Regional Vertebral Characteristics (cont. ) – Axis (C 2) • 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. 20 c The first and second cervical vertebrae. Posterior C 2 Spinous process Inferior articular process Lamina Pedicle Transverse process Superior articular facet Dens Body Superior view of axis (C 2) © 2016 Pearson Education, Inc.

Figure 7. 20 d The first and second cervical vertebrae. Posterior Transverse foramen in transverse process Spinous process Superior articular facet Dens Body Photo of axis (C 2), superior view © 2016 Pearson Education, Inc.

Figure 7. 21 a Posterolateral views of articulated vertebrae. Dens of axis Transverse ligament of atlas C 1 (atlas) C 2 (axis) C 3 Inferior articular process Bifid spinous process Transverse processes C 7 (vertebra prominens) Cervical vertebrae © 2016 Pearson Education, Inc.

Regional Vertebral Characteristics (cont. ) • Thoracic vertebrae – T 1 to T 12 increase in size and articulate with ribs – Unique characteristics: • Body is heart shaped with facets that articulate with ribs – T 10 to T 12 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 T 11, T 12) • Location of articular facets allows rotation of this area of spine © 2016 Pearson Education, Inc.

Figure 7. 21 b Posterolateral views of articulated vertebrae. Transverse process Superior articular process Transverse costal facet (for tubercle of rib) Intervertebral disc Body Spinous process Thoracic vertebrae © 2016 Pearson Education, Inc. Inferior costal facet (for head of rib) Inferior articular process

Regional Vertebral Characteristics (cont. ) • Lumbar vertebrae – L 1 to L 5 “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.

Figure 7. 21 c Posterolateral views of articulated vertebrae. Superior articular process Transverse process Spinous process Lumbar vertebrae © 2016 Pearson Education, Inc. Body Intervertebral disc Inferior articular process

Regional Vertebral Characteristics (cont. ) • Sacrum: triangular bone shapes posterior wall of pelvis; made from five fused vertebrae (S 1–S 5) – Facet of Superior articular process articulates with L 5 – 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 © 2016 Pearson Education, Inc.

Regional Vertebral Characteristics (cont. ) • Sacrum (cont. ) – Sacral canal: continuation of

Regional Vertebral Characteristics (cont. ) • Coccyx: tailbone formed from three to five fused

Figure 7. 22 a The sacrum and coccyx. Sacral promontory Ala Body of first sacral vertebra Transverse ridges (sites of vertebral fusion) Apex Anterior sacral foramina Coccyx © 2016 Pearson Education, Inc. Anterior view

Figure 7. 22 b The sacrum and coccyx. Sacral canal Ala Body Facet of superior articular process Auricular surface Lateral sacral crest Median sacral crest Posterior sacral foramina Coccyx © 2016 Pearson Education, Inc. Posterior view Sacral hiatus

7. 3 Thoracic Cage • Composed of: – 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. 23 a The thoracic cage. Jugular notch Clavicular notch Sternum True ribs (1– 7) • Manubrium • Sternal angle • Body • Xiphisternal joint • Xiphoid process False ribs (8– 12) Intercostal spaces © 2016 Pearson Education, Inc. L 1 Floating Vertebra ribs (11, 12) Skeleton of the thoracic cage, anterior view Costal cartilage Costal margin

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 (angle of Louis) • Horizontal ridge across front of sternum – Xiphisternal joint • Point where sternal body and xiphoid process fuse © 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 ribs (pairs 1– 7) – Attach directly to sternum by individual costal cartilages • False ribs (pairs 8– 10) – Attach indirectly to sternum by joining costal cartilage of rib above • Floating ribs (pairs 11– 12) – No attachment to sternum © 2016 Pearson Education, Inc.

Figure 7. 23 a The thoracic cage. Jugular notch Clavicular notch Sternum True ribs (1– 7) • Manubrium • Sternal angle • Body • Xiphisternal joint • Xiphoid process False ribs (8– 12) Intercostal spaces © 2016 Pearson Education, Inc. L 1 Floating Vertebra ribs (11, 12) Skeleton of the thoracic cage, anterior view Costal cartilage Costal margin

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 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.

Figure 7. 24 a Ribs. Transverse costal facet (for tubercle of rib) Angle of rib Superior costal facet (for head of rib) Body of vertebra Head of rib Intervertebral disc Neck of rib Tubercle of rib Shaft Crosssection of rib Sternum Costal groove Costal cartilage Vertebral and sternal articulations of a typical true rib © 2016 Pearson Education, Inc.

Figure 7. 24 b Ribs. Articular facet on tubercle of rib Spinous process Shaft Ligaments Neck of rib Head of rib Superior costal facet (for head of rib) Transverse costal facet (for tubercle of rib) Body of thoracic vertebra Superior view of the articulation between a rib and a thoracic vertebra © 2016 Pearson Education, Inc.

Figure 7. 24 c Ribs. Shaft Facets for articulation with vertebrae Junction with costal cartilage Head Neck Costal groove A typical rib (rib 6, right), posterior view © 2016 Pearson Education, Inc. Articular facet on tubercle Angle of rib