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Chapter 7 Vertebral Column/Thoracic Cage. Vertebral Column Location: – Forms the vertical axis of the skeleton General Structure: – Composed of vertebrae.

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Presentation on theme: "Chapter 7 Vertebral Column/Thoracic Cage. Vertebral Column Location: – Forms the vertical axis of the skeleton General Structure: – Composed of vertebrae."— Presentation transcript:

1 Chapter 7 Vertebral Column/Thoracic Cage

2 Vertebral Column Location: – Forms the vertical axis of the skeleton General Structure: – Composed of vertebrae – Vertenrae are separated by masses of fibrocartilage called intervertebral discs – Each intervertebral disc is connected to one another by ligaments Functions: – Supports the head and trunk – Protects the spinal cord, which passes through the vertebral canal (formed by openings in the vertebrae)

3 Vertebral Column Number of bones in an infant skeleton: – 33 bones Number of bones in an adult skeleton: – 26 bones Five bones are fused into the sacrum Four bones are fused to form the coccyx (tailbone)

4 Vertebral Column Curvatures: – Thoracic curvature Concave anteriorly Primary curve – Sacral curvature Concave anteriorly Primary curve – Cervical curvature Convex anteriorly Secondary curve – Develops when a baby begins to hold up its head – Lumbar curvature Convex anteriorly Secondary curvature – Develops when a child begins to stand

5 Typical Verterbra Body – Drum-shaped – Forms the thick, anterior portion of the bone – Longitudinal rows of bodies support the weight of the head and trunk

6 Typical Vertebrae Intervertebral discs – Separate adjacent vertebrae – Fastened to the roughened upper and lower surfaces of the vertebral bodies – Soften forces (such as from walking and jumping) that might fracture the vertebrae or injure the brain

7 Typical Vertebra Anterior longitudinal ligaments – Join adjacent vertebrae on the anterior surface Posterior longitudinal ligaments – Join adjacent vertebrae on the posterior surface

8 Typical Vertebrae Vertebral Foramen – Opening through which the spinal cord passes

9 Typical Vertebrae Vertebral Arch – Surrounds the vertebral foramen – Formed by: Pedicles – Two short stalks that project posteriorly from each vertebral body to form the sides of the vertebral foramen Spinous process – Posterior projection formed by the fusion of two plates called laminae – Serves as an attachment for various ligament sand muscles

10 Typical Vertebrae Transverse process – Projects laterally and posteriorly between the pedicles and laminae – Serves as an attachment for various ligament sand muscles

11 Typical Vertebrae Superior articulating process – Projects upward from each vertebral arch – Has cartilage-covered facets by which each vertebrae is joined to the one above it Inferior articulating process – Projects downward from each vertebral arch – Has cartilage-covered facets by which each vertebrae is joined to the one above it

12 Typical Vertebrae Intervertebral foramina – Formed by aligning notches on the lower surfaces of the vertebral pedicles – Provide passageways for spinal nerves that pass between adjacent vertebrae and connect to the spinal cord

13 Cervical Vertebrae Seven vertebrae that form the neck – Smallest of the vertebrae – Have the densest bone tissues

14 Cervical Vertebrae Special features: – Transverse processes have transverse foramina, which serve as passageways for arteries leading to the brain – Spinous processes of the 2 nd through 6 th cervical vertebrae are forked (bifid) to provide attachments for muscles – Spinous process of the 7 th cervical vertebra is longer and called the vertebra prominens

15 Cervical Vertebrae 1 st cervical vertebra is called the atlas and supports the head – Hardly has a body or spine – Appears as a bony ring with two transverse processes – Has two kidney-shaped facets on its superior surface that articulate with the occipital condyles 2 nd cervical vertebra is called the axis – Has a toothlike process called the dens, or odontoid process that projects upward and into the ring of the atlas As the head turns from side to side the atlas pivots around the dens

16 Thoracic Vertebrae 12 vertebrae below the cervical vertebrae Special features: – Transverse processes project posteriorly at sharp angles – Spinous processes are long and pointed and slope downward – Bodies have facets on each side that articulate with ribs – Beginning with the third thoracic vertebra, each vertebra increases in size to bear the increasing load of body weight

17 Lumbar Vertebrae 5 vertebrae in the small of the back Special Features – Have larger and stronger bodies than vertebrae above them as they have to support more weight – Have thinner transverse processes that project laterally – Have short thick spinous processes that project posteriorly and nearly horizontally

18 Sacrum Consists of 5 vertebrae that gradually fuse together between the ages of 18 and 30 Forms the posterior wall of the pelvic cavity

19 Sacrum Special Features: – Spinous processes are fused to form a ridge of tubercules called the median sacral crest – Joined to the coxae of the pelvis at its auricular surfaces by fibrocartilage of the sacroiliac joints – The upper anterior margin of the sacrum (or the first sacral vertebra) is called the sacral promontory – Posterior sacral foramina are located to the sides of the tubercules and allow nerves and blood vessels to pass through – Vertebral foramina of the sacral vertebrae form the sacral canal which opens at the tip of the sacrum (called the sacral hiatus) Opening exists because the laminae of the last sacral vertebrae are not fused – Four pairs of anterior sacral foramina are located on the ventral surface and allow passageways for nerves and blood vessels

20 Coccyx Tailbone Usually consists of 4 vertebrae that fuse by the 25 th year. Cushions the force of sitting Attached to the margins of the sacral hiatus by ligaments

21 Thoracic Cage Includes the ribs, the thoracic vertebrae, the sternum, and the costal cartilages (attach ribs to sternum) Functions: – Support the shoulder girdle and upper limbs – Protect the viscera in the thoracic and abdominal cavities – Play a role in breathing

22 Ribs Usual number is 24 (one pair attached to each of the 12 thoracic vertebrae) – Some people can develop extra ribs associated with the cervical or lumbar vertbrae True ribs (vertebrosternal ribs) – First seven rib pairs – Join the sternum directly by costal cartilage False ribs (vertebrochondral ribs) – Remaining five pairs – Cartilages of the upper three pairs of false ribs join the cartilage of the 7 th rib – The last two pairs have no attachment to the sternum, so they are called floating ribs (or vertebral ribs)

23 Ribs A typical rib has a long slender shaft which curves around the chest and slope downward An enlarged head is located at the posterior end and articulates with a facet on the body of its own vertebra and the next highest vertebra Neck of the rib is flattened, lateral to the head, where ligaments attach A tubercle that is close to the head of the rib articulates with the transverse process of the vertebra

24 Ribs Costal cartilages are composed of hyaline cartilage and are attached to the anterior ends of the ribs (and contour in line with them toward the sternum)

25 Sternum Breastbone Flat elongated bone located along the midline in the anterior portion of the thoracic cage Develops in three parts: – An upper manubrium The manubrium usually remains as a separate bone until middle age or later when it fuses to the body of the sternum – A middle body – A lower xyphiod process that projects downward The xiphoid process begins as a piece of cartilage, slowly ossifies, and fuses to the body of the sternum by middle age The sides of the manubrium and the body are notched where they articulate with costal cartilage The manubrium also articulates with the clavicles by facets on its superior border


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