Section 1: Structure and Function of the Spine

Health Fields Advanced

What is the anatomy of the spine?

33 vertebrae

• C1- C2 cervical

• T1- T12 thoracic (ribs attach here)

• L1- L5 lumbar

• 5 fused sacral

• 3-5 fused coccyx

S shaped structure

Part of AXIAL skeleton

What is the role of spinal anatomy?

Consists of bones, ligaments, tendons, nerves and muscles that serve to:

• Support and enclose spinal cord

• Hold the head and torso upright

• Provides a place for muscles to attach

• Allows for mobility

What is the purpose of spinal curves?

Spinal curves work like a coiled spring to absorb shock, maintain balance and allow range of motion (ROM) throughout spinal column

What is Atlas (C1)?

Named after greek God Atlas

• Atlas was titan God condemned by Zeus to bear weight of heavens on his shoulders = endurance

• C1 bears weight of our head

What is Axis and Atlas?

Top 2 cervical vertebrae are unique in design

• Atlas (C1): supports head

• Axis (C2): promotes movement of axis

Collectively C1 and C2 allow for minor:

• Flexion (C1): allows us to say “yes”

• Rotation (C2): allows us to say “no”

What are the primary+secondary curves and disorders?

Lord/o

• swayback

• concave (inward)

• “Lordosis”

• lumbar

Kyph/o

• roundback

• convex (outward)

• “Kyphosis”

• thoracic

Scoli/o

• curvature

• lateral (side)

• “Scoliosis”

• thoracic

What are the 4 curvatures in Vertebral column?

Purposes of curves:

• Disperse force

• Increase strength

• Flexibility and ROM

• Ability to absorb shock

Primary (Kyphotic) Curvature

• thoracic and sacral/coccyx curves

• present from birth

• convex (outward)

Secondary (Lordotic) Curvature

• concave (inward)

• after birth

• cervical and lumbar arch

Are the back curve disorders higher in men or women?

Lordosis: higher in women

Scoliosis: higher in women

Kyphosis: higher in men and age related in older women

What is the SI joint?

Sacroiliac joint is a synovial joint

Connection between spine and pelvis

2-4 mm of movement in any direction (very little)

• Attach to sacrum

• Absorb weight of walking, moving and allows flexibility

Synovial Joint: most common and movable type of joint

• Fluid filled cavity (synovial cavity)= free movement between bones

What are the bone marking categories?

1. Projection = Process: any bone extension, projection or bump

2. Passage = Foramen: rounded passageway for blood vessels and nerves

3. Articulation point (smooth surface that form joints) = Facet: small, flat articular surface

What is the function of individual vertebrae?

Protect spinal cord and nerve roots

Bear body weight

Attachment for MMs and tendons

NOT all are alike but share common characteristics

What is the anatomy of a typical vertebrae?

Divided into 2 parts:

• Anterior (facing chest): includes vertebral body

• Posterior (facing back): includes vertebral arch and processes that attach to the arch

What is the Anterior portion of vertebrae?

Vertebral body: weight bearing portion of vertebrae

What is the posterior portion of vertebrae?

Make up vertebral arch and protect spinal cord

Vertebral arch and processes

What is the vertebral arch?

Formed by:

• 2 pedicles

• 2 lamina

What are processes?

Structures that attach to vertebral arch

7 vertebral processes in total

• Transverse: 2

• Articular: 2 superior and 2 inferior = 4 total

• Spinous: 1

NOTE: articular processes also contain facets (articular surfaces)

What is the anatomy of facet joints?

Facet: region of contact is called articular facet

• Where 2 superior and inferior facets join = Facet joint

What are intervertebral discs?

Form a “vertebral sandwich”

23 in spine

4 cm in diameter, 7-10 mm thick

Form cartilaginous joint (allowing little movement)

Absorb shock and prevent friction between vertebrae

Help with movement

What are the 2 regions of intervertebral discs?

Annulus Fibrosus

• makes up exterior of discs

• made up of fibrocartilage

• strongest part of disc

• connects each vertebrae together

Nucleus Pulposus

• composed of gel like material with high water content

• cushions and provides flexibility

Do we shrink as we get older?

Yes after age 40 we shrink ¼ - 1/3 of an inch every 10 years

• Mainly due to loss of water in intervertebral discs

NOTE: osteoporosis with disc loss, increasing the risk of vertebral fractures

What are foramen?

Opening/passageway = spinal cord and nerves

Vertebral foramen: opening in vertebrae where spinal cord runs through

Intervertebral foramen: passageway between vertebrae where nerve roots exit

What is the spinal cord and spinal nerves?

Spinal cord: carries nerve impulses between brain and spinal nerves

Spinal nerves (31 pairs): sends signals from spinal cord to rest of body

What is Cauda Equina? AKA “horses tail”

Collection of 10 pairs of nerves at the end of spinal cord (some of which combine to form larger nerves in body. Ex. Sciatic nerves

Function: send and receive messages between the lower limbs and pelvic organs, which consists of bladder, rectum and internal genital organs