L/S Anatomy

Question 1

describe the body of a typical lumbar vertebrae

Answer 1

1. weight-bearing component of structure
2. “kidney shaped”
3. shell of cortical bone, inner cancellous bone
4. ring apophysis: ring on periphery of caudal and cranial surfaces

Question 2

describe typical lumbar pedicles

Answer 2

1. short (stout) w/very thick walls
2. transmit force from posterior components to vertebral bodies

Question 3

describe typical lumbar transverse processes

Answer 3

1. project posteriolaterally
2. mammillary processes on superior articular process

Question 4

describe the orientation of typical lumbar spinous process

Answer 4

nearly horizontal

Question 5

what is the function of lamina?

Answer 5

protect neural structures

transmit forces from articular and spinous processes

Question 6

where is the pars interarticularis and what is it’s function?

Answer 6

1. between S/I articular processes
   
   • oblique from lateral border of lamina to upper border
2. transmits forces from horizontal pedicle to vertically oriented lamina

*subject to frx

Question 7

describe foramen in the lumbar spine

Answer 7

1. Spinal
   
   • triangular
   • larger than T/S but smaller than C/S
   • L1 contains conus medullaris
   • L2-5 contain cauda equina and spinal meninges
2. Intervertebral
   
   • superior notches are shallow
   • inferior are deep

Question 8

list the ligaments at the lumbar spine

Answer 8

1. posterior longitudinal
2. anterior longitudinal
3. Interspinous
4. Supraspinous
5. Ligamentum flava
6. Iliolumbar ligament

Question 9

describe the posterior longitudinal ligament

Answer 9

blends w/IV discs

spans from posterior body of C2 to sacrum

Question 10

describe the anterior longitudinal ligament

Answer 10

thick and pearly

mostly attaches to margins of anterior vertebral bodies

Question 11

describe the interspinous ligament

Answer 11

attaches superior to inferior SP

paired-filled w/fat

likely proprioceptive in nature

Question 12

describe the supraspinous ligament

Answer 12

attaches to tips of spinous processes

less common in lower lumbar region

Question 13

describe the ligamentum flava

Answer 13

attach adjacent lamina

thick, yellow, elastic

checks flexion motion

medial edge fuses w/contralateral ligament (closes vertebral canal)

Question 14

describe the Iliolumbar ligament

Answer 14

spans from transverse process of L5 to anteriomedial surface of ilium

prevents anterior slipping of L5 on sacrum

resists motions of rotation, flexion, and lateral flexion

Question 15

List musculature involved with the lumbar spine

Answer 15

1. Back muscles
   
   • erector spinae
   • multifidus
   • interspinales
   • intertransversarii
2. QL
3. Abdominal muscles
   
   • TrA
   • Internal oblique
   • External oblique
4. Psoas major

Question 16

what is the role of the erector spinae?

what is their innervation?

Answer 16

1. group of muscles important for stabilization of curvature
   
   • compressive loads
2. innervation: spinal nerves
   
   • medial branch of posterior ramus

Question 17

what is the largest and most medial of the lumbar muscles?

Answer 17

Multifidus

Question 18

describe the multifidi

Answer 18

1. spinotransverse group
2. several fasicles w/varied origin/insertion
3. stabilizer against shear during rotation
4. eccentrically control flexion of vertebrae inter-segmentally when oblique abdominal muscles rotate the spine

Question 19

how do multifidi impact zygophyseal joints?

Answer 19

they insert onto zygophyseal joint capsules

they pull the capsules out of the way during extension or during motions when the joints are closing down

Question 20

what is the origin and insertion of the external oblique?

Answer 20

1. originates lateral ribs 5-12
2. attaches to:
   
   • inguinal ligament
   • linea alba
   • ASIS
   • iliac crest
   • pubic tubercle

Question 21

what is the action/role of the external oblique?

Answer 21

1. Bilateral activation
   
   • vertebral column flexor
   • posterior rotation of pelvis
2. Unilateral activation
   
   • trunk lateral flexors

Question 22

what is the origin and attachments of the internal oblique?

Answer 22

1. attaches to:
   
   • inguinal ligament
   • thoracolumbar fascia
   • iliac crest
   • pubic crest
   • TrA
   • costal cartilage of ribs 7-9

Question 23

what is the role/actions of the internal oblique?

Answer 23

1. assists w/postural control during static and dynamic activities
2. bilateral activation
   
   • vertebral column flexor
   • respiration
3. unilateral activation
   
   • trunk rotator

Question 24

what is the origin and attachments of the TrA?

Answer 24

1. Origins:
   
   • inguinal ligament (lateral third)
   • anterior 2/3 iliac crest (inner lip)
   • thoracolumbar fascia
   • lower (6) costal cartilages (along w/diaphragm)
2. Upper and middle fibers run transversely around trunk
   
   • blend w/fascia surrounding rectus abdominis
3. Lower fibers insert on pubic crest w/internal oblique

Question 25

what is the role/actions of the TrA?

Answer 25

1. lumbar and SIJ stabilizer 2. anticipatory activation prior to movement/perturbation

Question 26

what is the origin and attachment of the QL? what is it's innervation?

Answer 26

1. Origin → iliac crest and TP of spine 2. Insertion → 12th rib and spine (TP of lumbar vertebrae and lateral body of T12) 3. Innervated by ventral rami T12-L2

Question 27

what is the origin and insertion of the psoas major? what is it's innervation?

Answer 27

1. Origin → TP of lumbar vertebrae, T12-L5 bodies and IV discs 2. Insertion → tip of lesser trochanter 3. Innervated by ventral rami L1-L2

Question 28

what is the role of psoas major?

Answer 28

1. lumbar stabilizer * compressive loading on lumbar spine 2. lateral flexion moment on spine w/unilateral activation 3. important hip flexor

Question 29

what are the components of IV discs?

Answer 29

1. nucleous pulposus 2. annulus fibrosis 3. vertebral endplates \*there is no clear boundary between nucleus and annulus

Question 30

describe the nucleus of IV discs

Answer 30

1. semifluid, mucoid material 2. cartilage cells and irregularly arranged collagen fibers in semifluid ground matrix 3. deformed, but not compressed (fluid) * transmits pressure in all directions if deformed

Question 31

describe the structure of annulus

Answer 31

1. weight is 60-70% water 2. dry weight * 50-60% collagen → type I (resist tensile loading) * 20% proteoglycans * 10% elastic fibers 3. 10-20 lamellae arranged in concentric rings

Question 32

how does the thickness compare at different portions of the annulus?

Answer 32

1. thicker toward center of disc, anteriorly, and laterally 2. posteriorly the lamellae are thinner, finer, and more tightly packed

Question 33

describe the structure of the vertebral endplate

Answer 33

1. layers (0.6-1 mm thick) * hyaline cartilage → toward vertebral body * fibrocartilage → toward nucleus 2. covers superior/inferior vertebral body 3. covers nucleus, but not entire annulus 4. encircled by ring apophasis

Question 34

what is the function of IV discs?

Answer 34

1. allow movement between vertebral bodies 2. transmit loads between adjacent vertebral bodies 3. absorbs and stores energy

Question 35

how does the IV disc respond with compression?

Answer 35

annulus deforms and fluid "squeezed" from annulus annulus braces the disc nucles may be deformed, but not compressed

Question 36

how does the IV disc absorb and store energy?

Answer 36

1. collagen fibers of annulus stretch and store energy 2. attenuates speed of force transmission between vertebral bodies 3. elastic recoiling w/unloading = transmission of force to nucleus

Question 37

T/F: IV discs are poorly vascularized

Answer 37

TRUE for the inner discs there is some at the endplates at the outermost layers of annulus

Question 38

describe the articulations of zygophyseal joints

Answer 38

inferior articular process of a vertebra with the superior process of adjacent vertebra * superior facets = faces posteriomedially * inferior facet = faces anteriolaterally

Question 39

what is the function of facet joints in the lumbar spine?

Answer 39

guide and limit movement of spine

Question 40

what type of joints are facet joints?

Answer 40

synovial

Question 41

since facet joints are synovial, describe their structure

Answer 41

1. synovial lining that is surrounded by a capsule 2. 2 layers: * outer collagen * inner elastic fibers 3. thick dorsally, reinforced by multifidi 4. ballons superiorly and inferiorly 5. tiny foramen in inferior and superior poles 6. articular cartilage → 2 mm in height

Question 42

T/F: the surface of facet joints are all the same

Answer 42

FALSE they vary in shape and orientation may be flat, or inferior facet may be concave

Question 43

T/F: facet joints have fibro-adipose meniscoids

Answer 43

TRUE they transmit loads and protect articular cartilage that would otherwise be exposed during motion (they are also highly innervated)

Question 44

describe the kinematics of lumbar flexion

Answer 44

1. Facet joints * forward sliding of Inf articular process on superior process by 5-8 mm * "opening" of joints bilaterally, compression at end-range flexion 2. Disc * compression of annulus anteriorly * stretching of annulus posteriorly 3. Lateral foramen * "open" (widen) as motion increases

Question 45

describe the kinematics of lumbar extension

Answer 45

1. Facet joints * downward movement of inferior articular process * compression of joint * joints become weight-bearing 2. Disc * stretching of annulus anteriorly 3. Lateral foramen * "close" (narrow) as motion increases

Question 46

describe the general trends for mean ranges for lumbar kinematics

Answer 46

1. Mid to upper L/S get a good amount of lateral flexion 2. Not much axial rotation throughout 3. Less extension generally speaking 4. Combined flexion and extension results in range from 13-16

Question 47

what coupling motions occur at facet joints w/lateral flexion in the lumbar spine?

Answer 47

most commonly coupled w/extension though variable in direction

Question 48

what coupling motions occurs at facet joints with rotation in the lumbar spine?

Answer 48

coupling w/flexion and extension motions variable

Question 49

describe lateral flexion and axial rotation coupling trends in the lumbar spine

Answer 49

1. L1/L2-L3/L4 → contralateral rotation and lateral flexion motions 2. L4/L5 → variable 3. L5/S1 → ipsilateral lateral flexion and rotation motions