A2 - Vertebral column Flashcards
What are the functions of the vertebral column?
1- Protection: encloses spinal cord in spinal canal
2: Support: weight of body above pelvis
3: Axis: central axis of the body
4: Movement and posture
What are the primary and secondary curvatures of the spine?
Primary: in foetus, concave
- Thoracic
- Sacral
Secondary: develops later in life, convex
- Cervical
- Lumbar
When do the secondary curvatures of the spine develop?
Cervical - develops around 6 months (when baby learns to hold head up)
Lumbar - develops at around 1 year (balance and walking)
What is kyphosis? What can it be caused by?
Spine is curving drastically outwards in the thoracic region
Cause: erosion of the anterior part of 1 or more vertebrae
What is lordosis? What can it be caused by?
Spine curves drastically inwards at the lumbar spine
Cause: weakened trunk and obesity
When does the spinal cord end?
L1 - L2
What level is the conus medullaris at?
L1
What is the joint between adjacent vertebrae?
Zygopophyseal (facet) joint: synovial articulation between superior and inferior facets of adjacent vertebrae
What are zygopophyseal joints strengthened by?
- Ligamentum flavum: between lamina of adjacent vertebrae
- Interspinous ligament: between spinous processes of adjacent vertebrae
- Supraspinous ligament: between tips of adjacent vertebral spines
- Intertransverse ligament: between adjacent transverse processes
What is the supraspinous ligament referred to as in the cervical spine?
Nuchal ligament
What 2 ligaments strengthen the vertebral column?
Anterior longitudinal ligament: thick, prevents hyperextension of the vertebral column
Posterior longitudinal ligament: weaker, prevents hyperflexion
What articulates at the atlanto-occipital joint?
Synovial articulation between occipital condyles and superior facets of C1
What articulates at the atlanto-axial joint?
Synovial articulation between dens and lateral mass of C2, with the anterior arch and lateral mass of C1
What ligament is unique to the lumbar spine?
Iliolumbar ligament - strengthens the lumbosacral joint (L5/S1)
Where does the apical ligament attach?
Odontoid process to anterior margin of foramen magnum
Where does the alar ligament attach?
Odontoid process to the medial side of the occipital condyles
Where does the cruciate ligament attach (transverse and vertical parts)?
Transverse: inner aspect of each lateral mass, holds the dens against the anterior arch of the atlas
Vertical: between the posterior surface of the body of axis and anterior border of the foramen magnum
Where are the internal and external venous plexuses? Which drains into the other?
Internal - inside the vertebral foramen/ canal
External - outside the vertebrae
Internal drains into the external plexus
What is the basivertebral vein? Where is it found?
Joins the venous plexuses draining the vertebrae
it lies across the body
What are the 2 arteries supplying blood to the vertebral column and where are they derived?
Anterior spinal: from vertebral arteries
Posterior spinal: from vertebral or posterior inferior cerebellar arteries
What articulates at the atlanto-axial joint?
Synovial articulation between dens and lateral mass of C2, with the anterior arch and lateral mass of C1
List the features of a typical vertebrae
Spinous process - posteriorly
Lamina - connects transverse and spinous processes
Superior articular processes - form joints between vertebrae
Pedicles - connects vertebral body to transverse processes
Transverse processes - extend laterally and posteriorly (in thoracic vertebrae they articulate with ribs)
What features distinguish cervical vertebrae?
- Bifid spinous process: bifurcates except for C1 (no spinous process) and C7
- Transverse foramina: opening in transverse processes, where vertebral vessels pass through
- Triangular shaped vertebral foramen
What features distinguish C1 vertebrae?
Lack of spinous process
Has lateral masses (area around superior articular facet) - where transverse processes arise off
What features distinguish C2 vertebrae?
Dens / odontoid process
What features distinguish C7 vertebrae?
Long and thin spinous process
What features distinguish thoracic vertebrae?
Demi-facets: 2x, to articulate with heads of 2 ribs
Costal facet: on transverse process, articulates with the shaft of the rib
Long and thin spinous process - points down and behind
Circular vertebral foramen
Vertebral body is heart-shaped
What features distinguish lumbar vertebrae?
Large, kidney-bean shaped vertebral bodies
Triangular vertebral foramen
Shorter spinous processes that are quadrangular (not a thin projection)
For zygopophyseal joints:
- What type joint is it?
- What movement is allowed?
Synovial type joint
Movements: flexion, extension, lateral flexion, rotation
What type of joint is it between vertebral bodies?
Symphysis joint - a secondary cartilaginous joint
Indirect joint - intervertebral disc between
What joints make up the atlanto-axial joint and what type are they?
1 x median atlanto-axial joint = pivot-type
Between the dens of C2 and articular facet of C1
2 x lateral atlanto-axial joint = plane-type
Between inferior and superior facets of C1 and C2
What movement can occur at atlanto-axial joints?
Principle action: axial rotation
Limited flexion, extension and lateral flexion
What type of joint is the atlanto-occipital joint?
Condyloid (synovial joint)
What movement can occur at the atlanto-occipital joint?
Principle actions: flexion and extension
Limited lateral flexion
What ligaments support the atlanto-occipital joint
Anterior atlanto-occipital membrane: connects the anterior arch of the atlas to the anterior margin of the foramen magnum
Posterior atlanto-occipital membrane: connects the arch of the atlas to the posterior margin of the foramen magnum
What articulates at the costovertebral joints?
Head of the rib articulates with:
- Superior costal facet of corresponding vertebrae
- inferior costal facet of superior vertebrae
- Intervertebral disc separating the 2 vertebrae
What type joint is the costovertebral joint?
Synovial plane joint
What is the annulus fibrosus?
Peripheral part of the intervertebral disc
Binds to anterior and posterior longitudinal ligaments, inserts into epiphyseal rim of the vertebral body. Has concentric layers of fibrocartilage.
What is the nucleus pulposis? what is it composed of?
Central core of the intervertebral disc
Composed of semiliquid gelatinous structure, approx 90% water at birth and 70% at old age. The liquid structure means it can change shape and permit movement. It is avascular.
Where do spinal nerves run?
They pass through the foramina that is below the corresponding vertebrae, unless its cervical verebrae and then the spinal nerves run above
What is the filum terminalis?
Non-functional continuation of the spinal cord (fibrous tissue)
How are the dorsal and ventral rami formed?
Dorsal horn -> dorsal root
Ventral horn -> ventral root
Dorsal + ventral root -> spinal nerve
Spinal nerve -> dorsal and ventral rami
What fibres do the spinal nerve, dorsal rami and ventral rami contain?
They all contain both sensory and motor fibres
Where does the spinal nerve exit the vertebral canal? What does it split into?
Via intervertebral foramina, splits into:
- Posterior rami = synovial joints of vertebral column, deep muscles of back, overlying skin
- Anterior rami = remainder of body
What is the number of spinal segments in each part of the vertebral column?
C: 8
T: 12
L: 5
Sacral: 5
Coccyx: 1
What are the nerve roots of the sciatic nerve?
L4-S2
What are the motor functions of the sciatic nerve?
Innervates muscles of posterior thigh and the hamstring portion of the adductor magnus.
Also indirectly innervates leg and foot muscles via its terminal branches
What are the sensory functions of the sciatic nerve?
No direct functions but indirect sensation (via terminal branches) to the skin of the lateral leg, heel and dorsal and plantar surfaces of the foot
What is the anatomical course of the sciatic nerve?
1: derived from lumbosacral plexus
2: leaves pelvis via greater sciatic foramen and enters the gluteal region
3: emerges beneath the piriformis muscle
4: descends and enters the posterior thigh passing deep to the biceps femoris
5: reaches apex of popliteal fossa, bifurcates into the tibial and common fibular nerves
Where does the tibial nerve provide innervation to?
Posterior leg and some intrinsic foot msucles
Where does the common fibular nerve provide innervation to?
Anterior leg, lateral leg and remaining intrinsic foot muscles
What is the endoneurium?
connective tissue surrounding a single nerve fibre
What is a fascicle?
Bunch of nerve fibres
What is the perineurium?
Connective tissue surrounding a fascicle
What is a nerve?
A group of fascicles
What is the epineurium?
Connective tissue surrounding a nerve
Motor neurons in the spinal cord are pyramidal of shape and vary in size. What are the largest of these cells called?
Betz cells
What are the 3 categories of ganglia?
Sensory - no synapses, nerve cell bodies of first order neurons (unipolar)
Sympathetic - synapses, in vertebral chain or anterior to
Parasympathetic - has synapses, close to organs
Are neurons unipolar, bipolar or multipolar in sympathetic ganglia?
Multipolar
Describe histologically what the sensory ganglia looks like
Nerve cell bodies are round with a centrally located nuclei
NCBs are close together
Can see white axon strips coming in
Nuclei in connective tissue (fibroblasts)
Describe histologically what sympathetic ganglia looks like
Nerve cell bodies are smaller and more spread out (because they’re multipolar so have lots of dendrites)
Doesn’t look as neat a pattern as sensory ganglia
Where are parasympathetic ganglia found?
Between the 2 layers of muscle fibres (inner circular and outer longitudinal)
