back anatomy

Question 1

functions of the vertebral column

Answer 1

1. muscle attachment
2. mobility
3. protection
4. weight transfer
5. haematopoiesis

Question 2

parts of the vertebral column

Answer 2

• 7 cervical vertebrae
• 12 thoracic vertebrae
• 5 lumbar vertebrae
• 5 fused sacral vertebrae
• 1 coccyx

Question 3

primary vs secondary curvature of the vertebral column

Answer 3

kyphosis vs lordosis:
- curves forward vs curves backwards
- starts in foetal development vs develops post birth
- protects internal organs vs balances body weight
- thoracic and sacral kyphosis vs cervical and lumbar lordosis

Question 4

parts of a spinal vertebrae

Answer 4

• vertebral body
• vertebral arch
• 7 processes: 1 spinous process, 2 transverse processes, 4 articular processes
• vertebral notches (superior and inferior)

Question 5

types of joints between spinal vertebrae

Answer 5

1. intervertebral discs: between vertebral bodies
   - anulus fibrosus: thick outer ring of fibrous cartilage
   - nucleus pulposus: elastic flexible inner area
   - cartilaginous endplates
2. zygapophysial joints: between articular processes of adjacent vertebrae
   - joint capsule contains synovial fluid

Question 6

why is C1 (atlas) an atypical cervical vertebrae?

Answer 6

• no body or spinous process
• superior articular surface articulates with occipital condyles (back of skull) and is more concave

Question 7

why is C2 (axis) an atypical vertebrae?

Answer 7

• dens/odontoid process projects upwards from body as a pivot for the atlas and head
• atlas rotates on flat superior articular facets
• anteriorly: vertebral body + dens + 2 pedicles + transverse processes
• posteriorly: 2 laminae + spinous process
• anterior and posterior aspects together create the vertebral canal

Question 8

identifying features of cervical vertebrae

Answer 8

• small body
• triangular vertebral foramen
• short bifid spinous process
• foramen transversarium allows passage of vertebral arteries and veins
• articular processes for lots of movement

Question 9

identifying features of thoracic vertebrae

Answer 9

• medium sized body
• circular vertebral foramen
• long spinous process (protects spinal cord)
• costal facets for articulation of ribs
• intervertebral foramen provides passage for spinal cord and blood vessels

Question 10

identifying features of lumbar vertebrae

Answer 10

• large body
• large vertebral foramen
• short spinous process
• accessory process (on transverse process) and mammillary process (on superior articular process) for muscle attachment
• no transverse foramen

Question 11

identifying features of sacral vertebrae

Answer 11

• FUSED
• wedge shaped
• foramina allow the passage of sacral spinal nerves

Question 12

identifying features of coccyx

Answer 12

• small and triangular
• fusion of 4 rudimentary coccygeal vertebrae

Question 13

extrinsic superficial back muscles

Answer 13

trapezius, latissimus dorsi, rhomboid major, rhomboid minor, levator scapulae

Question 14

trapezius origin, insertion, innervation

Answer 14

origin: skull nuchal line, processes of C7-T12
insertion: lateral aspect of clavicle, acromion, spine of scapula
innervation: spinal accessory nerve

Question 15

latissimus dorsi origin, insertion, innervation

Answer 15

origin: T6-T12 processes, thoracolumbar fascia, iliac crest, lower 3/4 ribs
insertion: bicipital groove of humerus
innervation: thoracodorsal nerve

Question 16

rhomboid muscles origin, insertion, innervation

Answer 16

origin: T2-T5 (major), nuchal ligament and C7-T1 (minor)
insertion: medial border of scapula (major), medial scapular spine (minor)
innervation: dorsal scapular nerve

Question 17

levator scapulae origin, insertion, innervation

Answer 17

origin: transverse processes of C1-C4
insertion: medial border of scapula, above spine
innervation: cervical nerves and dorsal scapular nerve

Question 18

extrinsic intermediate back muscles + function

Answer 18

serratus posterior superior: elevates ribs 2-5 (innervated by nerves T2-T5)
serratus posterior inferior: depresses ribs 9-12 (innervated by nerves T9-T12)

Question 19

intrinsic superficial back muscles + function

Answer 19

splenius capitis + splenius cervicis: ipsilateral head rotation

innervated by posterior ramu

Question 20

intermediate intrinsic back muscles + function

Answer 20

erector spinae muscles: iliocostalis, longissimus, spinalis

unilaterally laterally flex the spine, bilaterally extend the spine and head

Question 21

deep intrinsic back muscles + function

Answer 21

semispinalis (extends and contralaterally rotates head and spine), multifidus (stabilises spine), rotatores (stabilises spine), levator costarum (elevates ribs), interspinale (stabilises spine), intertransversari (stabilises spine)

Question 22

ligaments of the vertebral canal

Answer 22

anterior longitudinal ligament, posterior longitudinal ligament, ligamentum flavum, interspinous ligament, supraspinous ligament, intertransverse ligament, nuchal ligament

Question 23

where does the spinal cord terminate?

Answer 23

L1

Question 24

which nerves form the cauda equina?

Answer 24

L2-S5: lumbar and sacral nerves

Question 25

where does the spinal cord narrow and enlarge?

Answer 25

narrows: conus medullaris (S1, termination of spinal cord), filum terminale (remnant of the caudal part of the spinal cord) enlarge: brachial plexus (C4-T1) and lumbosacral enlargement (L1-S3)

Question 26

parts of the spinal meninges

Answer 26

dura mater, arachnoid mater, pia mater

Question 27

arterial supply of the vertebral canal

Answer 27

- anterior spinal artery: branches of vertebral arteries - posterior spinal artery: anastamosis of vertebral artery and posterioinferior cerebellar artery - also supported by medullary segmental arteries and radicular arteries

Question 28

venous drainage of the vertebral canal

Answer 28

- 3 anterior and 3 posterior spinal veins + medullary and radicular veins - drain into internal and external vertebral plexus --> into systemic segmental veins or dural venous sinuses

Question 29

role of cartilage in connective tissue

Answer 29

- provide a smooth articular surface at bony ends - shock absorption - structural support - promotes osteogenesis

Question 30

constituents of cartilage

Answer 30

chondrocytes (secrete collagen fibres and ground substance), ground substance (proteoglycans, sulphated glycosaminoglycans, hyaluronic acid)

Question 31

types of cartilage

Answer 31

- hyaline cartilage (avascular w poor repair, found at articular ends of bone) - elastic cartilage (resilient and pliable, contains branching and anastamosing elastic fibres, found at external ear and external auditory canal) - fibrocartilage (combination of elastic and hyaline cartilage, shock absorbing, lacks perichondrium, found at intervertebral discs and pubic symphysis)

Question 32

functions of bone

Answer 32

support, movement, protection, blood formation, electrolyte balance, acid-base balance, energy storage

Question 33

parts of a bone

Answer 33

- periosteum: fibrous outer and osteogenic underlayer - marrow cavity: holds red and yellow bone marrow - articular cartilage - epiphysis (end) and diaphysis (shaft) - metaphysis and growth plate in children - compact bone

Question 34

parts of an osteon (inner to outer)

Answer 34

1. central canal (Volkmann canals with blood vessels and nerves run perpendicularly) 2. concentric lamellae with collagen 3. osteocytes 4. lacunae 5. canaliculi

Question 35

compact bone vs spongy bone

Answer 35

- outer layer of bones and shafts of long bone vs interior of bone - contains osteons and Volkmann canals vs no osteons - no space between layers of bone tissue vs spongy with marrow cavities - don't contain marrow vs contain red (haematopoietic) and yellow (fat) marrow

Question 36

organic components of a bone (1/3 of the bone)

Answer 36

1. collagen fibres 2. ground substance 3. cells: osteoblasts (create bone matrix), osteocytes (detect mechanical load on bones), osteoclasts (cause matrix resorption), osteoprogenitor cells (stem cells from mesenchymal tissue)

Question 37

inorganic components of bone

Answer 37

**calcium phosphate**, calcium carbonate/fluoride, magnesium, sodium, **hydroxyapatite crystals**

Question 38

types of bone ossification

Answer 38

1. intermembranous: direct conversion of mesenchymal tissue to bone 2. endochondral: conversion of mesenchyme to cartilage --> slowly replaced by bone

Question 39

hormones stimulating bone growth

Answer 39

thyroid hormones, growth hormone, parathyroid hormone (vs calcitonin - inhibits bone growth), sex hormones