Axial Skeleton: Vertebral Column Slides by Vince Austin; figures from Marieb & Hoehn 7 th & 8 th...

Axial Skeleton: Vertebral Column

Slides by Vince Austin;

figures from Marieb & Hoehn 7th & 8th eds.;

modifications and some slides by W. Rose

Portions copyright Pearson Education

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings

Vertebral Column

26 irregular bones (vertebrae) connected to form a flexible curved structure

Cervical vertebrae – 7 bones of neck

Thoracic vertebrae – 12 bones of torso

Lumbar vertebrae – 5 bones of lower back

Sacrum – bone inferior to the lumbar vertebrae that articulates with the hip bones (fusion of 5, starts ~> puberty, done mid-20s)


Vertebral Column

Figure 7.13

Spinal nerves C1-C7 exit above vertebrae C1-C7

Spinal nerve C8 exits above T1

Spinal nerves T1-T12, L1-L5, S1-S5 exit below vertebrae T1-T12, L1-L5, S1-S5

Kyphotic

Kyphotic

Lordotic

Lordotic


Vertebral Column: Curvatures

Kyphosis = posteriorly convex curvature. Thoracic and sacral normally kyphotic (but not too much).

Lordosis = posteriorly concave curvature. Cervical and lumbar normally lordotic (but not too much).

Abnormal spinal curvatures

• Scoliosis (lateral curve)

• Excessive kyphosis (hunchback)

• Excessive lordosis (swayback)

• What happens in pregnancy?


Vertebral Column: Ligaments

Anterior and posterior longitudinal ligaments – continuous bands down the front and back of the spine from the neck to the sacrum

Short ligaments connect adjoining vertebrae together


Vertebral Column: Ligaments


Vertebral Column: Intervertebral Discs

Cushion-like pad composed of two parts

Nucleus pulposus – inner gelatinous nucleus that gives the disc its elasticity and compressibility

Annulus fibrosus – surrounds the nucleus pulposus with a collar composed of collagen and fibrocartilage


Vertebral Column: Intervertebral Discs


General Structure of Vertebrae

Body or centrum – disc-shaped, weight-bearing region

Vertebral arch – composed of pedicles and laminae that, along with the centrum, enclose the vertebral foramen

Vertebral foramina – make up the vertebral canal through which the spinal cord passes



Spinous processes project posteriorly, and transverse processes project laterally

Superior and inferior articular processes – protrude superiorly and inferiorly from the pedicle-lamina junctions

Intervertebral foramina – lateral openings formed from notched areas on the superior and inferior borders of adjacent pedicles



transverse costal facet for tubercle of rib

superior demifacet; must be a T

heart-shaped in Ts, oval in Ls

part of the facet joint


Cervical Vertebrae

Seven vertebrae (C1-C7): smallest, lightest vertebrae

C3-C7: Distinguished by oval bodies, short spinous processes, large, triangular vertebral foramina. Articular facets (sup & inf) form joints with vetrebrae above & below.

Each transverse process contains a transverse foramen. (Only cervical have transverse foramina.)


Cervical Vertebrae

Table 7.2.2


Cervical Vertebrae: Atlas (C1)

No body, no spinous process

Anterior and posterior arches, and two lateral masses

Superior surfaces of lateral masses articulate with occipital condyles


Cervical Vertebrae: The Atlas (C1)

Figure 7.16a, b


Cervical Vertebrae: Axis (C2)

Body, spine, and vertebral arches, like other cervical vertebrae

Unique feature: dens, or odontoid process, projects superiorly from body, cradled in the anterior arch of the atlas

The dens is a pivot for the rotation of the atlas

The “missing body” of the atlas?


Cervical Vertebrae: The Axis (C2)

Figure 7.16c


Cervical Vertebrae: Atlas, Axis (C1, C2)

Figure 7.17a


Regional Characteristics of Vertebrae

Table 7.2.1


Regional Characteristics of Vertebrae

Table 7.2.2


Thoracic Vertebrae

Twelve vertebrae (T1-T12), each of which articulates with one or two of the twelve ribs

Major markings include: • Superior, inferior articular facets (vertebrae above, below)• Sup, inf costal facets (“demifacets”) on heart-shaped body (rib heads)

(T10, T11, T12 have single costal facets)

• Circular vertebral foramen• Transverse processes with transverse costal facets (rib tubercles) (not T11,

T12)

• Long spinous process

Location, orientation of articular facets prevents sagittal plane flexion and extension, but allows rotation and limited lateral flexion, of thoracic spine


Thoracic Vertebrae

Figure 7.17b


Lumbar Vertebrae

The five lumbar vertebrae (L1-L5) are located in the small of the back and have an enhanced weight-bearing function

They have short, thick pedicles and laminae, flat hatchet-shaped spinous processes, and a triangular-shaped vertebral foramen

Orientation of articular facets locks the lumbar vertebrae together to provide stability


Lumbar Vertebrae

Figure 7.17c


Sacrum

Sacrum

Consists of five fused vertebrae (S1-S5), which shape the posterior wall of the pelvis

It articulates with L5 superiorly, and with the auricular surfaces of the hip bones

Major markings include the sacral promontory, transverse lines, alae, dorsal sacral foramina, sacral canal, and sacral hiatus


Coccyx

Coccyx (Tailbone)

The coccyx is made up of four (in some cases three to five) fused vertebrae that articulate superiorly with the sacrum


Sacrum and Coccyx: Anterior View

Figure 7.18a


Sacrum and Coccyx: Posterior View

Figure 7.18b

Axial Skeleton: Vertebral Column Slides by Vince Austin; figures from Marieb & Hoehn 7 th & 8 th...

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Transcript of Axial Skeleton: Vertebral Column Slides by Vince Austin; figures from Marieb & Hoehn 7 th & 8 th...