back anatomy Flashcards
functions of the vertebral column
- muscle attachment
- mobility
- protection
- weight transfer
- haematopoiesis
parts of the vertebral column
- 7 cervical vertebrae
- 12 thoracic vertebrae
- 5 lumbar vertebrae
- 5 fused sacral vertebrae
- 1 coccyx
primary vs secondary curvature of the vertebral column
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
parts of a spinal vertebrae
- vertebral body
- vertebral arch
- 7 processes: 1 spinous process, 2 transverse processes, 4 articular processes
- vertebral notches (superior and inferior)
types of joints between spinal vertebrae
- intervertebral discs: between vertebral bodies
- anulus fibrosus: thick outer ring of fibrous cartilage
- nucleus pulposus: elastic flexible inner area
- cartilaginous endplates - zygapophysial joints: between articular processes of adjacent vertebrae
- joint capsule contains synovial fluid
why is C1 (atlas) an atypical cervical vertebrae?
- no body or spinous process
- superior articular surface articulates with occipital condyles (back of skull) and is more concave
why is C2 (axis) an atypical vertebrae?
- 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
identifying features of cervical vertebrae
- small body
- triangular vertebral foramen
- short bifid spinous process
- foramen transversarium allows passage of vertebral arteries and veins
- articular processes for lots of movement
identifying features of thoracic vertebrae
- 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
identifying features of lumbar vertebrae
- 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
identifying features of sacral vertebrae
- FUSED
- wedge shaped
- foramina allow the passage of sacral spinal nerves
identifying features of coccyx
- small and triangular
- fusion of 4 rudimentary coccygeal vertebrae
extrinsic superficial back muscles
trapezius, latissimus dorsi, rhomboid major, rhomboid minor, levator scapulae
trapezius origin, insertion, innervation
origin: skull nuchal line, processes of C7-T12
insertion: lateral aspect of clavicle, acromion, spine of scapula
innervation: spinal accessory nerve
latissimus dorsi origin, insertion, innervation
origin: T6-T12 processes, thoracolumbar fascia, iliac crest, lower 3/4 ribs
insertion: bicipital groove of humerus
innervation: thoracodorsal nerve
rhomboid muscles origin, insertion, innervation
origin: T2-T5 (major), nuchal ligament and C7-T1 (minor)
insertion: medial border of scapula (major), medial scapular spine (minor)
innervation: dorsal scapular nerve
levator scapulae origin, insertion, innervation
origin: transverse processes of C1-C4
insertion: medial border of scapula, above spine
innervation: cervical nerves and dorsal scapular nerve
extrinsic intermediate back muscles + function
serratus posterior superior: elevates ribs 2-5 (innervated by nerves T2-T5)
serratus posterior inferior: depresses ribs 9-12 (innervated by nerves T9-T12)
intrinsic superficial back muscles + function
splenius capitis + splenius cervicis: ipsilateral head rotation
innervated by posterior ramu
intermediate intrinsic back muscles + function
erector spinae muscles: iliocostalis, longissimus, spinalis
unilaterally laterally flex the spine, bilaterally extend the spine and head
deep intrinsic back muscles + function
semispinalis (extends and contralaterally rotates head and spine), multifidus (stabilises spine), rotatores (stabilises spine), levator costarum (elevates ribs), interspinale (stabilises spine), intertransversari (stabilises spine)
ligaments of the vertebral canal
anterior longitudinal ligament, posterior longitudinal ligament, ligamentum flavum, interspinous ligament, supraspinous ligament, intertransverse ligament, nuchal ligament
where does the spinal cord terminate?
L1
which nerves form the cauda equina?
L2-S5: lumbar and sacral nerves
where does the spinal cord narrow and enlarge?
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)
parts of the spinal meninges
dura mater, arachnoid mater, pia mater
arterial supply of the vertebral canal
- 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
venous drainage of the vertebral canal
- 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
role of cartilage in connective tissue
- provide a smooth articular surface at bony ends
- shock absorption
- structural support
- promotes osteogenesis
constituents of cartilage
chondrocytes (secrete collagen fibres and ground substance), ground substance (proteoglycans, sulphated glycosaminoglycans, hyaluronic acid)
types of cartilage
- 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)
functions of bone
support, movement, protection, blood formation, electrolyte balance, acid-base balance, energy storage
parts of a bone
- 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
parts of an osteon (inner to outer)
- central canal (Volkmann canals with blood vessels and nerves run perpendicularly)
- concentric lamellae with collagen
- osteocytes
- lacunae
- canaliculi
compact bone vs spongy bone
- 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
organic components of a bone (1/3 of the bone)
- collagen fibres
- ground substance
- cells: osteoblasts (create bone matrix), osteocytes (detect mechanical load on bones), osteoclasts (cause matrix resorption), osteoprogenitor cells (stem cells from mesenchymal tissue)
inorganic components of bone
calcium phosphate, calcium carbonate/fluoride, magnesium, sodium, hydroxyapatite crystals
types of bone ossification
- intermembranous: direct conversion of mesenchymal tissue to bone
- endochondral: conversion of mesenchyme to cartilage –> slowly replaced by bone
hormones stimulating bone growth
thyroid hormones, growth hormone, parathyroid hormone (vs calcitonin - inhibits bone growth), sex hormones
