بنام مهربانترين

The vertebral column

General Features of the Vertebral Column

• 26 vertebrae & discs of fibrocartilage between them

• Five vertebral groups– 7 cervical in the neck– 12 thoracic in the chest– 5 lumbar in lower back– 1 sacrum– 1 coccyx

Newborn Spinal Curvature

• Spine exhibits one continuous C-shaped curve

• Known as primary curvature

Adult Spinal Curvatures

• S-shaped vertebral column with 4 curvatures

• Secondary curvatures develop after birth– lifting head as it begins to

crawl develops cervical curvature

– walking upright develops lumbar curvature

Abnormal Spinal Curvatures• Result from disease,

posture, paralysis or congenital defect

• Scoliosis from lack of proper development of one vertebrae

• Kyphosis is from osteoporosis

• Lordosis is from weak abdominal muscles

Scoliosis

Lordosis

Kyphosis

General Structure of a Vertebra

• Body

• Series of vertebral foramen form the vertebral canal

• Arch – 2 lamina– 2 pedicles

• Processes– spinous– transverse– articular (superior & inferior)

Intervertebral Foramen & Discs• Intervertebral foramen

– formed from vertebral notches of adjacent vertebrae

– passageway for spinal nerves

• Intervertebral discs

Cervical

Typical Cervical Vertebrae

• Smaller body and larger vertebral foramen• Transverse process short with transverse foramen for

protection of vertebral arteries• Bifid or forked spinous process in C2 to C6

The Unique Atlas and Axis

• Atlas (C1) supports the skull– concave superior articular facet

– ring surrounding large vertebral foramen

• anterior & posterior arch

• Axis (C2)– dens or odontoid process is held in

place inside the vertebral foramen of the atlas by ligaments

– allows rotation of head

Atlas & Axis Articulation

Thoracic

Typical Thoracic Vertebrae

• More massive body than cervical but smaller lumbar

• Spinous processes pointed and angled downward

• Superior articular facets face posteriorly permitting some rotation between adjacent vertebrae

• Rib attachment– facets & hemifacets on vertebral body and costal facets at ends of transverse processes for

articulation of tubercle of ribs 1 to 10

Lumbar

Lumbar Vertebrae

• Thick, large body, squarish spinous process• Superior articular processes face medially

Sacrum

Sacrum (Anterior View)

• Anterior surface– smooth & concave

– sacral foramina were intervertebral foramen

• nerves & blood vessels

– 4 transverse lines indicate line of fusion of vertebrae

Sacrum (Posterior View)

• Rough surface of sacrum• Spinous processes have

fused into median sacral crest

• Transverse processes fuse into lateral sacral crest

• Posterior sacral foramina• Sacral canal ends as sacral

hiatus• Auricular surface is part of

sacroiliac joint

Coccyx

• Single, small, triangular bone• Provides attachment site for

muscles of pelvic floor• Cornua

– hornlike projections on Co1 for ligaments attach coccyx to sacrum