Lecture 6 Flashcards
Which spinal segments contribute to the primary curve of the back?
Thoracic
Sacral
What is the purpose of the spinal curves ?
To absorb and transmit forces and retaining the centre of gravity.
Which spinal segments contribute to the secondary curve of the back and why?
Cervical
IVD are thicker anteriorly
Lumbar
IVD and vertebral bodies are thicker anteriorly
What are abnormal curves of the back?
Hyperlordosis - lumbar
Kyphosis - thoracic
Scoliosis - lateral, idiopathic
What are the features of a typical vertebral structure?
Body: cancellous/spongy bone surrounded by compact bone, takes majority of weight.
Transverse & spinous processes: act as levers.
Pars interarticularis: common fracture site, base of spinous process.
Vertebral foramen.
Vertebral arch: pedicles and lamina.
Elevated ring around edge of vertebral body: bony/apophysis, IVD insert here, hyaline cartilage plate.
Inferior and superior vertebral notches: form intervertebral foramen.
What are the features of thoracic vertebrae?
Heart shaped vertebral body.
Small round intervertebral foramen.
Long spinous processes that point downward.
Demi facets on vertebral bodies for ribs.
Articular facets are in the coronal plane.
Facets for rib tubercle on transverse process.
What movements occur in the thoracic spine?
Articular facets are in the coronal plane.
Limits flexion and extension.
Some lateral flexion.
Some rotation.
What are the features of lumbar vertebrae?
Large kidney shaped vertebral body. Most weight bearing vertebrae. Triangular shaped intervertebral foramen. Long thin transverse processes. Hatchet shaped spinous processes. Facets in sagittal plane.
What movements occur in the thoracic spine?
Articular facets are in the sagittal plane.
Allows flexion and extension.
What is particular about the L5 vertebrae?
It’s inferior facets are turning into the coronal plane to stop it from sliding off the top of the sacrum.
Which thoracic vertebrae are atypical?
T1
T11
T12
What are the features of the sacrum?
Ala/wings: fusion of transverse processes of S1-S3.
Anterior side is smooth.
Posterior side is bony.
Sacral promontory: most anterior section.
Sacral foramina: allow ventral/dorsal rami to leave the sacral canal.
Auricular surface: ear shaped hyaline cartilage, synovial part of sacro-iliac joint.
Sacral hiatus: bottom of posterior side.
Sacral cornu: palpable, site for epidural anaesthetia injection.
Why are the superior articular processes of S1 important?
Facets are in the coronal plane to stop L5 from sliding off.
Holds the inferior articular facets of L5 in place.
What does the intervertebral foramen contain?
Anterior and posterior nerve roots.
Epidural fat.
Blood vessels.
Nerves.
What does the vertebral canal contain?
Pia mater
Arachnoid mater
Dura mater
Epidural space: veins and epidural fat (buffers and protects)
Which nerves exit above vertebrae and which nerves exit below vertebrae?
C1-C7 exit above
C8 exits below
T1-T12 exit below
Where does the spinal cord end?
L1-L2
Where does the dura and arachnoid end?
S2
What is the lumbar cistern?
CSF pouch that contains the cauda equina.
What is the filum terminale?
Thin cord that attaches to the coccyx and continues down to anchor the spinal cord.
What is the blood supply of the vertebral column?
AORTA
Abdominal aorta > lumbar artery > spinal branch of lumbar artery
What is the venous drainage of the vertebral artery?
Internal vertebral venous plexus:
No veins, blood flows in either direction depending on pressure in the thorax and abdomen.
External vertebral venous plexus:
Both provide an alternate pathway for blood fro, the pelvic organs to each the heart.
What is the vertebral column innervated by?
Recurrent meningeal nerve:
Outer 1/3 of IVD
PLL
Anterior dura
Posterior ramus:
Zygophyseal joints
Skin
Overlying muscles of vertebral column - intrinsic back muscles
What are the two joints of the spine?
Synovial joints
Zygophyseal
Symphyses
IVD
What are the longitudinal ligaments?
Anterior longitudinal ligament:
Limits extension
Attach to anterior side of vertebral bodies and IVD
Posterior longitudinal ligament:
Fans out
Not stuck down - gaps to allow blood entry
Reinforcing
What are the segmental ligaments?
Ligamentum flavum
Intertransverse ligament
Interspinous and supraspinous ligaments
Iliolumbar ligament
What are extrinsic back muscles and what are the two layers?
What are they innervated by?
Muscles that are on the back but act on the upper limbs and ribs.
Superficial layer.
Intermediate layer.
Anterior rami (except trapezius CN11)
What muscles are in the extrinsic superficial layer?
Trapezius Rhomboid major Rhomboid minor Levator scapulae Latissimus dorsi
What are the muscles of the extrinsic intermediate layer?
Serratus posterior superior
Serratus posterior inferior
What are the intrinsic back muscles and what are the two groups?
What are they innervated by?
True muscles of the back - on the back and act on the back. Stabilisers. Superficial group - erector spinae. Deep group - transversospinalis. Posterior rami.
What are the superficial intrinsic back muscles?
Erector spinae muscles:
Iliocostalis (lateral)
Longissimus
Spinalis (medial)
Prime movers of the spine.
Long muscles.
Control flexion.
Contract eccentrically when you lean forward.
Prevent you from collapsing forward, maintains centre of gravity.
Side bending: only one side contracts.
What are the deep intrinsic back muscles?
Transversospinalis muscles:
Semispinalis: prominent in the neck (4-5 segments)
Multifidous: lumbar
Rotatores: thoracic (1-2 segments)
Short, cross segments.
Some rotation and extension but mostly stability.
What are the functions of the back?
Protect spinal cord Movement Attachment for ribs and pelvis Base for head and limbs Weight transfer and shock absorption RBC production (axial only after adolescence)
