Chapter 6 Anatomy: The Vertebral Column

Intervertebral discs are composed of two parts:

Nucleus puloposus • Inner gelatinous nucleus • Gives discs its elasticity and compressibility Anulus fibrosis • Outer collar composed of collagen and fibrocartilage. Limits expansion of nucleus pulposus when compressed

Scapulae Bone Features

Spine: prominent ridge posteriorly Acromion: lateral projection that articulates with acromial end of clavicle to form acromioclavicular joint Caracoid process: anterior projection that anchors bicep muscle of arm Suprascapular notch: opening for nerves Several large fossae named according to location

Cervical Vertebrae 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 o Occipital condyles "carry" skull •Movement for nodding head

Cervical Vertebrae Axis

(C2) Has body and processes like other vertabrae 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"

Types of Ribs

-12 pairs form sides of thoracic cage -All attach to thoracic vertebra -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 Vertebral (floating) ribs (pairs 11-12) No attachment to sternum

Types of Ligaments...

-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

Pectoral girdle (shoulder girdle) consists of clavicles (anteriorly) and scapulae (posteriorly)

-Attach upper limbs to axial skeleton -Provide attachment sites for muscles that move upper limbs -Offer great degree of mobility because: Scapulae are not attached to axial skeleton Socket of shoulder joint is shallow and does not restrict movement

All have common structural pattern consisting of...

-Body- (centrum), the anterior weight bearing region -Vertebral arch composed of: Two pedicles: short pillars from sides of arch Two laminae: fused, flattened plates from posterior arch -Vertebral foramen: enclosure formed by body and vertebral arch coming together -Vertebral canal: serioes of vertebral foramina -Intervertebral foramina: lateral openings between vertebrae for passage of spinal nerves

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 passagewats C7 is vertebra prominens: large and can be felt through skin, so used as a landmark C1 (atlas) and C2 (axis) have unqie features

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

Intervertebral discs...

-Cushion-like pad sandwiched between vertebrae that act as shock absorbers

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

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

Abnormal spinal curvatures

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

Sacrum

-triangular bone shapes posterior wall of pelvis; made from five fused vertebrae (S1-S5) o Superior articular processes: articulares with L5 o Articulates inferiorly with coccyx and laterally with hip bones via its auricular surfaces, forming sacroiliac joints o Sacral promontory: anterosuperior margin o Transverse ridges: mark lines of fusion o Anterior sacral foramina: lie at lateral ends of ridges: act as openings for nerves and vessels o Alae: wing-like expansions

Regions and Curvatures

1. Cervical- consists of 7 vertebrae 2. Thoracic 12 Vertebrae 3. Lumbar- 5 vertebrae 4. Sacrum: one bone, formed from fusion of several bones, articulates with hip 5. Coccyx: also fused bones that form terminus of column

Ligaments help...

Along with trunk muscles. help support vertebral column

The appendicular system consists of

bones of the limbs and their girdles -Pectoral girdle Attaches upper limbs to body trunk -Pelvic girdle Attaches lower limbs to body trunk

Clavicles

o Collarbones o S- shaped sternal end articulates with sternum medially o Flattened acrominal end articulates laterally with scapula o Anchor muscles and act as braces to hold the scapulae and arms out laterally

General Characteristics of Vertebral Column

o Comprised of 26 irregular bones called vertebrae in 5 major regions. 24 are individual vertebrae. o Extends from skull to pelvis o Functions: to transmit weight of trunk to lower limbs , surround and protect spinal cord, provide attachment points for ribs and muscles o Protects and house spinal cord and provides column that supports entire body.

Functions of Sacrum...

o Protects vital organs of thoracic cavity o supports shoulder girdles and upper limbs o Provides attachment sites for muscles of neck, back, chest, and shoulders

Vertebrae have seven processes:

o Spinous process: projects posteriorly o Transverse processes: project laterally o Superior articular processes: protrude o Inferior articular processes: Protrude inferiorly

Sacrum is composed of...

o Thoracic vertebrae posteriorly o Sternum and costal cartilages anteriorly o Ribs laterally