W1: Spine Flashcards
How many vertebrae?
33
cervical 7
thoracic 12
lumbar 5
sacral 5
coccygeal 3-4 fused
Draw and label standard vertebrae
Distinguishing features of cervical
Bifid spinous process – the spinous process bifurcates at its distal end.
Exceptions to this are C1 (no spinous process) and C7 (spinous process is longer than that of C2-C6 and may not bifurcate).
Transverse foramina – an opening in each transverse process, through which the vertebral arteries travel to the brain.
Triangular vertebral foramen
Small body - not a lot of weight
Discuss C1
Atlas
Doesnt have a body or a spinous process
Supports occipital bone
Transverse ligament of the atlas - maintains odontoid process in contact with the anterior arch
Discuss C2
Prominent superior projection - dens axis or odontoid process
Discuss C7
Separation of S1 from the sacrum is termed “lumbarisation”, while fusion of L5 to the sacrum is termed “sacralisation”. These conditions are congenital abnormalities.
What passes through transverse foramina in cervical?
Discuss general thoracic
The spinous processes of thoracic vertebrae are oriented obliquely inferiorly and posteriorly
Circular vertebral foramen
Costal facets/demi facets
Which rib is an exception when it comes to articulation?
Discuss general lumbar
triangle shaped foramen
Their spinous processes are shorter than those of thoracic vertebrae and do not extend inferiorly below the level of the vertebral body
Interlocking facetts preventing rotation
Stabilisation of L5 & sacrum
Scotty dog on radiograph is transverse process
Main site of herniations
Discuss general sacrum
Anterior aspect:
Transverse ridge
Wings = ala of sacrum
Auricular surface of the sacrum - forms sacroiliac joint
Posterior aspect:
Posterior sacral and lateral sacral crests
Bottom = sacral hiatus
Sacral congenital abnormalities
Separation of S1 from the sacrum is termed “lumbarisation”, while fusion of L5 to the sacrum is termed “sacralisation”. These conditions are congenital abnormalities.
Discuss ligaments present throughout vertebral column
Anterior and posterior longitudinal ligaments: Long ligaments that run the length of the vertebral column, covering the vertebral bodies and intervertebral discs.
Ligamentum flavum: Connects the laminae of adjacent vertebrae.
Interspinous ligament: Connects the spinous processes of adjacent vertebrae.
Supraspinous ligament: Connects the tips of adjacent spinous processes.
(Note: In the cervical spine, the interspinous and supraspinous ligaments thicken and combine to form the nuchal ligament).
What is the alar ligament?
Joins dens of C2 to lateral margins of foramen magnum
Cruciform ligament
The cruciate ligament of the atlas (also known as the cruciform ligament) is an important ligamentous complex that holds the posterior dens of C2 in articulation at the median atlantoaxial joint. It lies behind a large synovial bursa (surrounded by loose fibrous capsule) and consists of two bands:
longitudinal band: attaches the body of the C2 (axis) to the clivus and foramen magnum in the midline, lying between the apical ligament and tectorial membrane. It is relatively weak and hence does not contribute any significant stability.
transverse band (also known as the transverse atlantic or atlantal ligament): attaches to a small tubercle on the medial cortex of the C1 (atlas) lateral masses on both sides anterior to the tectorial membrane and dura. It passes posterior to the dens, with a small intervening synovial capsule, fixing the dens to the posterior margin of the anterior arch of the atlas. It is the strongest ligament in the whole spine 2 and arguably the most important!
With the alar ligament, the transverse band is the primary stabiliser of the atlantoaxial joint 2.
Whiplash injury
Hyperflexion + hyperextension of cervical
Hangman fracture
bilateral fracture through the neural arch of the 2nd cervical vertebra with or without dislocation of the body of the axis upon that of the 3rd cervical vertebra.
Extrinsic muscles of the back
Posterior-axioappendicular muscles controlling upper limb movements
Includes the rhomboids, levator scapulae, trapezius and latissimus dorsi
Discuss rhomboids
Rhomboid major and rhomboid minor
Retract the scapula
Discuss levator scapulae
Scapular motion - elevation
Transverse processes –> medial border of scapula
Discuss trapezius
Discuss latissimus dorsi
Widest muscle in human body
Able to pull the inferior angle of the scapula in various directions, producing movements on the shoulder joint; internal rotation, adduction and extension of the arm. Moreover, it is an accessory respiratory muscle, as well as one of the main stabilizers of the spine during its various movements.
Discuss intrinsic muscles of the back
ct to maintain posture
and control the movements of the vertebral column.These muscles include the splenius muscles, erector spinae muscles (chief extensors) and the transversospinales muscles.
What muscles do lateral flexion? (in cervical)
scalene muscles
What are the major flexors or the vertebral column?
abdominal obliques and rectus abdominis
sternocleidomastoid
contraction of the sternocleidomastoid muscle laterally flexes the cervical vertebral column to the same side and rotates the head. Bilateral contraction of these muscles causes flexion of the cervical spine
Torticollis
Also known as wry neck
A multitude of conditions may lead to the development of torticollis including: muscular fibrosis, congenital spine abnormalities, or toxic or traumatic brain injury
The congenital muscular torticollis is the most common torticollis which is present at birth
Birth trauma or intrauterine malposition is considered to be the cause of damage to the sternocleidomastoid muscle in the neck
Other alterations to the muscle tissue arise from repetitive microtrauma within the womb or a sudden change in the calcium concentration in the body which causes a prolonged period of muscle contraction
Any of these mechanisms can result in a shortening or excessive contraction of the sternocleidomastoid muscle
Spina bifida
birth defect in which there is incomplete closing of the spine and the membranes around the spinal cord during early development in pregnancy.
There are three main types: spina bifida occulta, meningocele and myelomeningocele.Meningocele and myelomeningocele may be grouped as spina bifida cystica.
Occulta = hidden - hair/birthmark
Meningocele - meninges herniate, nervous system undamaged
Myelomeningocele - spinal cord protrudes
Hemivertebra
Hemivertebra is a rare congenital spinal malformation, where only one side of the vertebral body develops, resulting in deformation of the spine, such as scoliosis, lordosis, or kyphosis
Describe development
All of the principal components of the spine – bones, ligaments and muscles – develop from mesoderm of the somites (S on figs below). The vertebrae develop from the sclerotomes and the muscles from the myotomes of the somites
S = somites, NT = neural tube, N = notochord, NC = neural crest
At what level does the spinal cord end?
At S1 in the newborn (spec says L3-4); at L1, L2 in the adult.
Discuss joints of the vertebral column
Intervertebral joints – secondary cartilaginous joints (fibrocartilaginous intervertebral disc) located between vertebral bodies of vertebrae. Designed for weight-bearing, strength and shock absorption. Interver- tebral discs consist of a margin of fibrocartilage (annulus fibrosus), surrounding a central gelatinous core (nucleus pulposus).
Zygapophyseal (facet) joints – plane synovial joints between the inferior articulating facet of the superior vertebra with the superior articulating facet of the inferior vertebra.
Atlanto-occipital joint – condyloid synovial joints between superior articular surfaces of lateral masses of the atlas and the occipital condyles. - (flexion/extension, nodding)
Atlanto-axial joints – pivot synovial joint between the dens of the axis with the anterior arch of the atlas, and gliding synovial joints between the superior facets of the axis with the inferior facets of the lateral masses of the atlas. - (rotation, shaking head)
(cervical - flexion/extension, thoracic - rotation, lumar - flexion/extension)
Which ligaments prevent hyperextension?
What about hyperflexion?
Anterior longintudinal
Posterior longitudinal, supraspinosus
What surrounds the spinal cord and spinal nerve roots?
Describe extradural space
internal vertebral venous plexus and extradural fat
What space contains the CSF?
Subarachnoid space
Where does the subarachnoid space terminate?
S2
What is the end of the spinal cord called? Where does it happen? What anchors it to the coccyx?
Conus medullaris, L1-L2
What does the spinal cord divide into following conus medullaris?
Mass of lower lumbar and sacral nerve roots known as the cauda equina
Describe spinal nerve exit
At what level are lumbar punctures usually performed? When should they not be performed?
L3/L4
When raised ICP is suspected - risk of brainstem herniation.
What type of joint is an intervertebral disc?
Secondary cartilaginous
What is nucleus pulposus made of? What is it surrounded by?
composed largely of an extracellular matrix of proteoglycan and water, surrounded by a fibrous ring of collagen bundles, the annulus fibrosis. The collagen fibres are arranged in concentric partial rings organised at 120 degrees to each other and at 30 degrees to the intervertebral joint (see below).
What are the spine flexors and extensors supplied by?
Flexors (supplied by anterior primary rami of the spinal nerves) and extensors (supplied by posterior primary rami).
Discuss spine extensor group, flexor group and lateral group
Extensor group: Short muscles between two adjacent vertebrae are situated most deeply and are clearly primarily postural; progressively longer muscles extend up from the sacrum and lower vertebrae to the spinous processes, transverse processes and costal elements, and to the skull to extend the spine.
Flexor group: Muscles running anterior the cervical spine and lumbar spine (psoas major) aid flexion, but more powerful muscles are situated at a distance from the spine (sternomastoid in the neck; the abdominal wall muscle rectus abdominis for the lumbar spine).
Lateral group: A small degree of lateral flexion of the cervical and lumbar spine is possible. It is produced by scalene muscles in the neck and by abdominal muscles.
How many nerve roots are there?
31
8 cervical, 12 thoracic, 5 lumbar, 5 sacral and 1 coccygeal, though the dorsal root of C1 and the coccygeal roots are sometimes absent
Discuss spondylolisthesis
Spondylolisthesis s a condition of uncertain cause in which there is a defect in the pedicles of L5. The neural arch of L5 is held in position by the upper articular facets of the sacrum, but the rest of L5 including the spinal canal and cauda equina, can slip forward on the sloping upper border of the sacrum, compressing the nerve roots (panel (b) below). The defect is well seen on the oblique radiographs which produce the ‘scotty dog’ appearance – the dog appears to wear a radiolucent ‘collar’ around its neck (panel (d) below).
Ankylosing Spondylitis
Ankylosing spondylitis is an immune disorder of the joints of the vertebral column (lumbar and thoracic spine).
The articular cartilage, synovium and ligaments become chronically inflamed and eventually ossify.
The patient, usually male, complains of low back pain and has a fixed thoracic kyphosis.
What does this radiograph show?
Osteomalacia (rickets)
What type of scan is this?
CT
what are: A, S and SF?
A: Aorta S: Spinous process of lumbar vertebrae SF: Subcutaneous fat
What anatomical landmarks would you use to identify this level? (L4-5)
Tuffiers line is a line joining the highest point of the iliac crests. This is said to cross L4 or L4-5 space, however, this again is highly variable.
