VC week 3

Question 1

how many vertebrae in vertebral column?
regions?
when is this complete?

Answer 1

develops as 33, reduced to 24 + sacum & coccyx

cervical = 7
thoracic = 12
lumbar = 5 
sacrum = 1 (5 fused)
coccyx = 1 (4 fused)

sacral and coccygeal fusions do not start until 20, not completed until middle age

Question 2

functions of vertebral column?

Answer 2

protects spinal cord
body flexibility
mobility (intervertebral discs)

Question 3

cervical vertebrae?
features?
curve?
divided into?

Answer 3

7 vertebrae
smaller compared to other regions as bear less weight + distinguished by their great flexibility
lordotic curve

divided into 2 parts (atypical and typical) which differ anatomically and functionall

Question 4

typical cervical vertebrae?
features?

Answer 4

C3 - C6

pic is superior view

Question 5

features of typical cervical vertebrae?

Answer 5

• spinous process
  
  • bifid
  • projects posteriorly
• vertebral body
  
  • composed of trabecular bone surrounded by thin layer of compact bone
  • small - reflects amount of weight carried
• superior articular facet (zygapophyseal joint)
  
  • in addition to articular processes
  • flat and oval in shape
  • superior facet projects backwards, upwards + medially
• Laminae
  
  • bilateral, long + narrow
  • forms majority of the arch & links transverse process with spinous process
  • protrude posteromedially
• pedicles
  
  • bilateral
  • cylindrical bones that connect vertebral arch to the body
  • short, protrude posterolaterally
• articular processes
  
  • 4 = 2 superior and 2 inferior
  • flattened bone which face superiorly + inferiorly respectively
  • found at junction of pedicle + lamina
  • project laterally on both sides
• transverse process and foramina
  
  • has neural sulcus supplying pathway for spinal nerve
  • anterior part = costal process (in front of foremen laterally)
  • posterior part - true process (behind foramen laterally)
  • one foramen in each process to allow passage of vertebral arteries, veins + nerve plexus to supply the brain

Question 6

purpose of bifid cervical spinous process?

what about superficial muscles?

Answer 6

increases surface area for muscle attachments

due to their shortness, superficial muscles (e.g. trapezius + splenius capiits) attach to nuchal ligament instead of cervical vertebrae

Question 7

cervical vertebral body morphological differences?

Answer 7

(sex, ethnic origin + age)

vertebral bodies + foramina significantly wider, more elongated + higher in males

african americans have wider, elongated vertebral bodies in C3-C5 than european americans

heights of C3 + C4 smaller in AA regardless of sex

cervical vertebral bodies become wider and more elongated with age (elongation more obvious than width)

also change shape with age (round → oval)

also reduction in height with age

no changes to vertebral foramen size with age

Question 8

what does C1 articulate with?

Answer 8

Superior articular facet - occipital condyle of skull

inferior articular facet - lateral masses of C2

Question 9

C1 anterior arch features?

Answer 9

anterior arch has anterior tubercle - for attachment of longus colli muscles and anterior longitudinal ligament

has fovea dentis for articulation with odontoid process of the axis

upper border = atlantooccipital membrane for attachment with occipital boen above

lower border = anterior atlantoaxial ligament for attachment with axis below

Question 10

atypical vertebrae?

Answer 10

C1, C2, C7

Question 11

C1 also called?

osteological features?

structure?

Answer 11

C1 = atlas

• ring-shaped
• no vertebral body (instead there are bilateral masses that bear weight from the skull)
• no spinous process

structure

• between each lateral mass, there is an anterior and posterior arch
• on lateral masses are the facet surfaces:-
  
  • superior facet = upwards, deep curve, articulates with occipital condyle of skull
  • inferior facet = downwards, flat, articulates with superior facet of C2
• transverse process = longer than other vertebrae, more lateral than any other transverse process of cervical spine

Question 12

C2 also called?

osteological features?

Answer 12

C2 = called axis due to its function in rotating the head left and right (axis of rotation)

Dens = piece of bone that extends upwards from vertebral body + articulates with posterior surface of C1 anterior arch

has vertebral body (unlike C1)

has large bifid, spinous process (unlike C1)

bilateral masses = transmits weight

transverse processes = contain foramina transversarium, shaped like an L to permit lateral slanting of vertebral artery (remember C1 has lateral transverse foramen)

superior articular facets

inferior articular facets = positioned anteroinferiorly

thick pedicle + lamina

Question 13

function C7?

called?

osteological features C7 vertebrae?

Answer 13

C7 is transition between highly flexible cervical spine + rigid thoracic

very similar to thoracic vertebrae

called “vertebral prominens” because of its spinous process (palpable)

atypical features

• spinous process = not bifid, longest out of all CV, multiple muscles attach here, positioned postero-inferiorly
• transverse process = very small transverse foramen (sometimes absent), contains accessory veins instead of vertebral artery

Question 14

cervical spine joints?

cervical spine injuries?

Answer 14

76 individual joints

significant CSI:

• fracture
• dislocation/subluxation
• ligamentous tearing

Question 15

functions cervical spine?

normal kinematics? - IMPORTANT

Answer 15

anchors head so eyes are parallel to ground (helps vestibular system in ear maintain balance)

provides motility - view our surroundings

muscle attachment

spinal cord - vertebral bodies protect SC + vertebral arteries

Kinematics

• flexion = 80-90*
• extension = 70*
• lateral flexion = 20-45*
• rotation = 90*

Question 16

atlantooccipital joint? what does this mean?

articulatons?

surfaces lined with?

Answer 16

bilateral ellipsoid synovial joint between C1 and occipital condyle of skull

ellipsoid/condylar joints allow movement in 2 axes - AO joint can only assist in flexion + extension (limited lateral flexion)

• articulations = superior articular facet of C1 + occipital condyle of skull
• there is no IV disc between these surfaces, but articular surfaces are still lined with hyaline cartilage

Question 17

why is there limited ROM for atlantooccipital joint?

Answer 17

due to deep shape of articular facets

• hinders translational movements of the head
• restrains anteriorly, posteriorly + laterally
• gives stability + balance (head wont fall off lol)

Question 18

C1 atlantooccipital joint kinematics? (don’t confuse with cervical kinematics slide)

Answer 18

Flexion

• occurs in anteroposterior + transverse axis
• convex (inferior) surface of occipital condyles glide posteriorly over C1 articular facets
• results in occipital bone moving further away from C1 posterior arch in a nodding motion
• restricted to 5-10 degrees of flexion

extension

• occipital condyles slide anteriorly onto C1 articular facets
• decreased space between occipital condyles and arch of C1
• restricted extension of 10*

lateral flexion

• not a major movement
• limited to 5-8 degrees
• coupled (multiple movements) + double joint action
• contralateral movement of occipital condyle = anterior movement of one OC + posterior movement of other

Question 19

structures associated with atlantooccipital joint stability?

significance?

Answer 19

articular capsule = thin, both AO joints covered, fibrous tissue with synovial membrane

ligaments = nuchal ligament, alar ligament, lateral atrlantooccipital ligament

primary stability:

• anterior atlantooccipital membrane (continuation of anterior longitudinal ligament) = fibrous tissue, anterior border of foramen magnum → upper border of anterior arch of C1
  
  • = anterior LL provides additional stability
• posterior attlantooccipital membrane = spreads across posterior AO joint, posterior border foramen magnum → upper border of posterior arch of C1
  
  • = significant landmark for vertebral artery and C1 nerve

Question 20

craniovertebral joints?

Answer 20

AO joint and atlantoaxial joint

Question 21

intervertebral discs cervical spine?

type of joint?

function?

Answer 21

no IV disc between C0-C1 or C1-C2

C3-C7 = symphysis joint links the iV discs

they are secondary cartilaginous joints

control ROM of the spine

Question 22

ligaments of cervical spine?

Answer 22

anterior longitudinal ligament

lies anterior to vertebral body

tenses during cervical extension

posterior longitudinal ligament

lies posterior to vertebral body

stretches during cervical flexion

ligamentum flava

latin for yellow

connects laminae of each vertebrae

facilitates + controls flexion

ligamentum nuchae

extends from occipital protuberance + spreads across cervical spine

gives stability to head + neck - restricts flexion

also important muscle attachment site

Question 23

CSI’s occur where?

mortality?

Ax?

Dx?

Answer 23

⅓ of CSIs occur in craniocervical junction (OA + AA)

death is usually certain

Ax = RTAs

Dx = CT + MRI

Question 24

CSI’s occur where?

mortality?

Ax?

Dx?

Answer 24

⅓ of CSIs occur in craniocervical junction (OA + AA)

death is usually certain

Ax = RTAs

Dx = CT + MRI

Question 25

AO dislocation types? mechanism?

Answer 25

_Type 1_ common **ventral dislocation** _type II_ highly unstable **longitudinal distractions** (upward force) _type III_ rarest **dorsal dislocation** mechanism = **hyperextension** trauma to posterior AO (tectorial) membrane + lateral flexion

Question 26

C1 fracture Ax? types?

Answer 26

axial loading (force directed through top of the head → through spine) due to RTA ## Footnote _jefferson fracture/burst fracture_ = anterior + posterior arches of C1 atlas (occipital condyles press onto lateral masses causing breakage of A + P arches) _posterior arch fracture_ = related to hyperextension _anterior arch fracture_ = hyperflexion _lateral mass fracture_ = lateral flexion on one side of vertebrae (**note: burst + lateral mass fractures both involve rupture of transverse ligament)**

Question 27

ewrbe

Answer 27

A = jefferson fracture B = lateral mass fracture C = lateral mass fracture

Question 28

atlantoaxial joint made up of? movements? why is it significant?

Answer 28

AA joint made up of 2 joints:- ## Footnote median atlanto-axial joint (dens + transverse ligament) lateral atlanto-axial joint (lateral masses of atlas + axis) movements: principal movement - axial rotation (atlas supports skull and facilitates this) bi-axial movement nodding + shaking head by rotating around odontoid process (limited flexion, extension + lateral rotation) this is the most mobile part of the spine

Question 29

AA joint ligaments?

Answer 29

Odontoid process * osteoligamentous ring = anterior arch of atlas * transverse ligament = attached to atlas posteriorly, runs across posterior surface of odontoid process (pic = OA is nodding, AA is shaking?)

Question 30

vasculature of AA joint?

Answer 30

transverse foramina = left + right vertebral arteries give rise to basilar arteries which supply the brain

Question 31

musculature of AA joint? innervation?

Answer 31

muscles ## Footnote _anterior arch of atlas (attach to_ **_anterior tubercle_**_):_ longus colli muscles = weak flexor of cervical spine anterior longitudinal ligament = limits extension of spine + reinforces IV disc (both allow movement of atlas around odontoid process - nodding/rotation) posterior arch of atlas: rectus capitis posterior minor = extends head at the neck, also gives rise to nuchal ligament (in addition to other muscles)

Question 32

innervation of AA joint?

Answer 32

C1 nerve originates at atlas * sensory innervation to dura surrounding foramen magnum * geniohyoid muscle (via hypoglossal nerve) * rectus capitis anterior muscle * longus capitis muscle * thyrohyoid muscle (via hypoglossal nerve) * omohyoid via ansa cervicalis * sternohyoid via ansa cervicalis

Question 33

pathologies of AA joint?

Answer 33

_injury to atlas_ can damage vertebral arteries = neurological damage w/o blood supply to brain damage to axis + atlas can also cause paralysis _chiari_ part of cerebellum herniates through foramen magnum, fatal _Ehlers-Danlos_ loose ligaments (e.g. transverse ligament of atlas) can cause instability in AA joints can lead to dislocation

Question 34

what is a motion segment? made up of? also called?

Answer 34

-Smallest unit of the spine which has biomechanical characteristics i.e. smallest unit which allows movement ## Footnote made up of only 2 adjacent vertebrae + the ligaments that connect them also called the **functional** **unit/**building blocks of the spine

Question 35

motion segment components?

Answer 35

2 adjacent vertebrae Intervertebral disc Facet joints between vertebrae (superior + inferior articular processes) Soft tissues and ligaments

Question 36

vertebral body function? rim + centre? vertebral foramen? spinous + transverse processes?

Answer 36

vertebral body = load bearing cortical bone rim = resistant to bending + torsion cancellous bone centre = flexibility + structural support vertebral foramen = protects spinal cord during movement spinous + transverse processes = muscle attachment

Question 37

zygapophyseal joint? how does shape differ in spinal regions? thus…

Answer 37

facet joint - between inferior articular process on superior vertebra and superior articular process of inferior vertebra cervical + thoracic = plane surface (in cervical region allows flexion, extension, lateral flexion + rotation → in thoracic region allows lateral flexion + rotation) lumbar = joints have curved surface which only allows flexion + extension **thus shape of facet joint restricts movement of the motion segment**

Question 38

IV disc functions? (3) layers of IV disc? how is IV disc bound to vertebral bone?

Answer 38

_IV disc functions:_ shock absorber transmits mechanical load allows + manages motion in motion segment outer rim = **anulus fibrosis** (made of collagenous sheets called lamellae) - these sheets are strong but flexible = allows spinal column to bend centre = **nucleus pulposus,** gelatinous which alllows absoprtion of water to help anulus fibrosis maintain its stiffness IV disc bound to vertebral bone by the **endplate**

Question 39

spinal ligament function? (3)

Answer 39

Allow motion without muscle Protect spinal cord by restricting motion segment movement Absorb energy and protect spinal cord during quick movements

Question 40

when does development of vertebral column begin? develops from? explain stages in development

Answer 40

VC begins development on 17th day of gestation most of spinal column is developed from the **mesoderm** (nucleus pulposus derived from notochord which develops from **endoderm**) (annulus fibrosus + cartilage endplates derived from mesenchymal cells from sclerotomes) week 3 notochord + somites will develop week 4 notochord will cause somites to migrate the cells that migrate peripherally will form dermis + muscle cells that migrate to surround notochord + neural tube will become sclerotome → will later form spinal skeleton sclerotome will undergo resegmentation (cranial half of sclerotome fuses to caudal half of another) → go on to form actual vertebrae the portion of sclerotome that remains between the vertebrae go on to form **annulus fibrosis** notochord will regress from vertebrae by week 10 → go on to form nucleus pulposus number of notochord cells in nucleus pulposus decreases rapidly after birth with none present after 10 y/o - will be replaced by chondrocyte-like cells with lower metabolic activity

Question 41

Answer 41

A = sclerotomic segments seperated by less dense intersegmental tissue B = condensation + proliferation of sclerotomal cells around notochord forming the IV discs

Question 42

pathology of IV disc occurs where? risk factors for Iv disc disease?

Answer 42

most commonly occur in cervical + lumbar regions of the spine risk factors = age, obesity, genetics, smoking + trauma

Question 43

e.g. IV disc pathologies?

Answer 43

degenerated disc = tears in annulus fibrosis bulging/prolapsed disc = annulus fibrosus still intact but is protruding into spinal column erniated disc = nuclueos pulposus has protruded through annulus fibrosus into spinal column

Question 44

degenerative disc disease? epidemiology? Ax? what are these?

Answer 44

degeneration occurs much earlier in IV discs than in any other soft tissue DDD is most common IV disc problem + occurs in 30-50 y/o not actually a disease - caused by loss of proteoglycans + type II collagen fibres proteoglycans = glycosylated protein that can be found in most connective tissues, its function is to provide hydration to the cell in order to maintain hydrostatic pressure

Question 45

DDD consequences? Tx? common form?

Answer 45

although it is painful it is unlikely to cause disability - however, can worsen over time and become herniated disc Tx = non-surgical methods such as rest and NSAIDs common form of disc degeneration is thinning disc

Question 46

MRI scan

Answer 46

image shows different stages of disc degeneration using MRI A = normal disc B-D = intervertebral disc starts to become darker → means disc has lost water content E = thinning disc with osteophyte formation

Question 47

osteophyte? Ax? pathophys? most commonly found? can cause? Tx?

Answer 47

osteophytes (bony spurs) = fibrocartilage-capped bony outgrowth Ax = osteoarthritis disc degeneration can cause excessive movement of spinal joints - osteophytes form to try and stabilise spinal column can affect any bone but most commonly knee, **spine**, hands + feet can cause: spondylotic radiculopathy, spinal stenosis (narrowing of spinal canal), myelopathy (can cause paralysis) Tx = medication, physio (severe cases need surgery)

Question 48

x-ray

Answer 48

can also see osteophytes forming

Question 49

herniated disc types? explain Tx?

Answer 49

3 types: protrusion, extrusion + sequestrion ## Footnote protrusion (bulging/prolapsed disc) = IV disc is compressed and protrudes outwards extrusion = nucleus pulposus ruptures through annulus fibrosus sequestrion (free fragment disc) = nucleus pulposus ruptures through annulus fibrosus and leaks into spinal canal, completely separating from disc Tx = 60-90% of herniated discs can be treated with meds, physio + rest

Question 50

Answer 50

…

Question 51

Answer 51

CT scan shows a herniated disc in the lumbar region compressing the spinal nerves

Question 52

movements of VC? degrees of movements?

Answer 52

flexion extension axial rotation lateral flexion (lat flexion + rotation are associated movements, both take place with the other) degrees of these movements between motion segments differ throughout the vertebral column = difference in the IV disc thickness and articular process position

Question 53

forces acting on the spine?

Answer 53

axial compression - compressive force exerted vertically to spinal coloumn shear forces - IV discs move anterior relative to eachother

Question 54

moments? types in spine?

Answer 54

moments = torques = forces acting at a distance from axis of rotation torsional moments bending moments the movements subject the VC to forces moments

Question 55

what allows moments to occur in spine?

Answer 55

to allow bending + torsion of IV disc = outer lamella of annulus fibrosus has lots of collagen fibres which bend and stretch with movements + moments

Question 56

Answer 56

movements + movements in motion segment

Question 57

flexion + extension movements + forces?

Answer 57

flexion + extension occur as rotations in **sagittal plane** around **lateral axis** (see image) _flexion_ nucleus pulposus migrates **posteriorly** due to compression of anterior annulus (**anterior compression forces**) _extension_ nucleus pulposus migrates **anteriorly** due to compression of posterior annulus (**posterior compression forces**)

Question 58

axial rotation forces + movements? where does axial rotation occur? coupled with?

Answer 58

rotation of vertebrae around **longitudinal axis** in **transverse plane** ## Footnote the annular fibres that run in the **same** direction as the direction of movement = **relaxed** the annular fibres that run in the **opposite** direction as the direction of movement = **stretched** **results in compression of nucleus pulposus** there is no axial rotation at lumbosacral junction + very small degrees in lumbar region axial rotation + lateral flexion are coupled movements

Question 59

lateral flexion movement + forces?

Answer 59

lateral flexion occurs as lateral rotation in frontal/coronal plane ## Footnote flexing laterally to right side - right side of intervertebral disc is compressed + left side is stretched flexing laterally to left side - left side of intervertebral disc is compressed + right side is stretched

Question 60

axial compression force?

Answer 60

compressive forces increase from cervical vertebrae towards lumbar + sacral compression causes pressure build-up within nucleus pulposus as the nucleus is fluid-like it produces hydrostatic pressure which is isotropic - same in all directions to distribute load of the force, inner + outer margins of annulus swell outwards, anteriorly, posteriorly and laterally

Question 61

shear forces?

Answer 61

Experienced during actions like pushing or pulling vertebrae in the motion segment “slide” + disc is displaced in the direction of the force is applied can occur in the y axis (anteriorly/posteriorly) or in the x axis (laterally)

Question 62

moments in spine?

Answer 62

_torsional moments_ occur in plane perpendicular to axis of intervertebral disc (i.e. Z axis) causes twisting of spine annular fibres in direction of torsion become stretched _bending moments_ occur in plane parallel to axis of IV disc (i.e. X or Y) Y axis = flexion/extension bending X axis = lateral bending moment (opposite way round from image wtf) e.g during flexion upper body weight x distance from spine = bending moment

Question 63

force vs pressure?

Answer 63

* Force = load passing through vertebral column * Pressure = fluid (nucleus pulposus) - hydrostatic pressure