Spine part 1 and part 2 Flashcards
Functions of the Vertebral Column
Support: Weightbearing and posture
Movement: Muscles and ligament attachments support movement (including breathing)
Protection: Predominantly of the spinal cord
Haematopoeisis: Production of red and white blood cells in the bone marrow of the vertebral bodies
The Vertebral Column, how many vertebrae, how many regions?
Typically made up of 33 vertebrae, separated by intervertebral discs
5 regions
Most vertebrae have a common structure however there are some atypical examples
Curves in spine
Primary
- Develop in utero/as a foetus
Thoracic and sacrum
Secondary
- Develop after birth
- Cervical – Lifting Head
- Lumbar – Sitting up, walking
Spine Development information
The spine reaches maturity as:
Muscles and ligaments strengthen
Bones grow, reaching mature shape and size
Body:head ratio changes
Upper C-Spine matures by age 10, lower C-Spine by 14
Patterns of injury are affected by this
Children – Upper C-Spine
Adults – Lower C-Spine
Spine develops faster than the rest of the bones usually as it is important
Cervical Vertebral Trends structure
Body Shape: Oval
Foramen shape: Triangular
Spinous Process: Bifid (except C1 and C7)
Special feature: Smallest of the vertebrae / has transverse foramina (except C7 normally)
Thoracic vertebral trends structure
Body Shape: Heart
Foramen shape: Circular
Spinous Process: Steep downward angle
Special feature: Extra costal articular facets / prominent transverse processes
Lumbar vertebral trends structure
Body Shape: Kidney
Foramen shape: Triangular
Spinous Process: Spade-like
Special feature: Large and strong
Transverse Ligament does what?
MAINTAINS THE ODONTOID PROCESS OF THE AXIS IN THE CORRECT POSITION IN RELATION TO THE ATLAS
Damage to this ligament can affect the stability of the joint between the atlantoaxial joint.
Anterior and Posterior Longitudinal Ligaments information
ALL – extends the whole length of the vertebral column, anterior to the vertebral bodies
Function: Limits extension of the vertebral column and reinforces intervertebral discs
PLL – extends the whole length of the vertebral column, in close contact with the posterior surface of the bodies of the vertebral bones. Lies inside the vertebral canal.
Prevents hyperflexion of the vertebral column and prevents protrusion of the intervertebral discs.
those ligaments affect the stability of the spine
Ligamentum Flavum info and function
Connects the laminae of adjacent vertebrae from C2 to S1.
Covers the dorsal surface of the vertebral canal.
Function: To preserve upright posture and assist in returning to this following flexion
posterior to the foramen
Interspinous Ligament info and function
Extends between adjacent spinous processes from C1 to S1. Connects with ligamentum flavum and supraspinal ligament.
Function: To limit flexion
It sits between the spinous processes
Supraspinal ligament info and function
Location: Connects spinous processes from C7 down to sacrum
Function: To limit flexion and act as a midline attachment for other muscles
Ligamentum Nuchae info and function
Location: Attaches at the external occipital protuberance and extends along the spinous processes down to C7
Function: To limit flexion and provide attachment for some spinal muscles
The spinal cord overview of structure
Like the brain it is also surrounded by meninges and CSF.
Elongated, cylindrical structure that is situated in the vertebral canal
Protected from injury by the vertebral column
Extends from the base of the skull to the lumbar region.
Meninges layers in spinal cord
Dura matter, Subdural cavity Arachnoid matter, Subarachnoid cavity, Pia matter
How does the spinal cord leave the brain and important info
The spinal cord is continuous with the medulla oblongata, a part of the brain stem found at the level of C1 which contains many vital centres for life (e.g. cardiac centre, respiratory centre).
It is in the medulla oblongata that you will find the Decussation of the Pyramids – this is where the motor nerves from the motor area of the cerebrum cross from one side of the body to the other and continue to the spinal cord. This is why the left hemisphere of the cerebrum controls the right side of the body, and vice versa.
Spinal nerves, spinal cord, what happens throughout the vertebrate?
The spinal cord itself measures approximately 45 cm in an adult male, and is about as thick as the 5th digit of the hand.
There are 31 pairs of spinal nerves that leave the vertebral canal by passing through the intervertebral foramina formed by adjacent vertebrae. There are 8 cervical nerves, 12 thoracic, 5 lumbar, 5 sacral and 5 coccygeal. Each nerve has sensory and motor components
At L1, the lumbar, sacral and coccygeal nerves leave the spinal cord and extend downwards within the subarachnoid space of the vertebral canal forming a sheaf of nerves known as the cauda equina (horse’s tail).
How is the spinal cord split and how does the grey matter work?
The spinal cord is incompletely divided into 2 equal parts. Anteriorly by the median fissure (short and shallow), and posteriorly by the posterior median septum (deep and narrow).
When viewing the spinal cord in cross section, we can see that the arrangement of white matter and grey matter is reversed when compared to the structure of the brain. For the spinal cord, the H-shaped grey matter (the nerve cell bodies) are arranged in the centre, surrounded by the white matter (the nerve fibres and neuroglia).
The central part of the grey matter is known as the transverse commissure which is pierced by a central canal which continues from the fourth ventricle in the brain which contains CSF.
The posterior columns of grey matter are composed of sensory nerve cell bodies, stimulated by sensory impulses. They transmit sensory impulses towards the brain.
The anterior columns of grey matter are composed of cell bodies of motor neurones.
What are Intervertebral Discs?
Adjacent vertebral bodies are separated by intervertebral discs
Intervertebral discs have an outer rim of fibrocartilage (annulus fibrosis) and a central core of a soft gelatinous material (nucleus pulposus).
Thinnest in the cervical region, thickening as they move down the spine
Supported by the posterior longitudinal ligament to stay in place (see post-session work for ligaments!).
Functionally, they act as shock-absorbers and also contribute to the flexibility of the spine due to the cartilaginous joints they form.
Information about prolapsed intervertebral disc
Herniation of the nucleus pulposus, causing a protrusion of the annulus fibrosis and the posterior longitudinal ligament into the neural canal.
Most common cause of compression of the spinal cord and/or nerve roots
Lumbar region most common site, particularly L2 down (below the spinal cord) so injury occurs to nerve roots only.
If it occurs in the cervical region, the spinal cord can become compressed. This is a medical emergency.
Can occur suddenly, particularly in young adults undertaking strenuous activity, or progressively in older people due to degenerative disease.
Outcomes depend on size of hernia and duration of pressure. Can lead to paralysis, acute or chronic pain, compression of blood vessels, or local muscle spasms.
(Whitley et al, 2015)
C1 (an atypical vertebra) – Level 4 Recap
AKA Atlas
No body
Anterior and posterior tubercles
Lateral Masses and Transverse Processes laterally
Superior articular facet forms the atlanto-occipital joints
Facet on the anterior arch allows for articulation with the odontoid process of C2
C2 (an atypical vertebra) – Level 4 Recap
Consists of a body, pedicles, laminae, transverse processes and a bifid spinous process
Superiorly the articulation forms the atlanto-axial joints:
Median: the odontoid process of C2 and the posterior aspect of anterior arch of C1
Lateral: the inferior articular process of C1 and the superior articular process of C2
Inferiorly the C2 articulates with C3
Largest of the cervical vertebrae
Lateral atlanto-axial joints are plane joints (glide)
Medial atlanto-axial joint is a pivot joint (rotational movement)
Together these make the atlanto-axial joint the most mobile of the spine
AP C1-C3 peg view information/appearance
For trauma
Less commonly seen in practice now as patients are likely to have a CT when traumatic injury to the C-Spine is suspected
Full positioning descriptor is available in Clark’s Positioning in Radiography (Whitley et al, 2015) – 13th edition, p.201 available as e-book online
A well positioned C1-C3 projection should demonstrate the alignment of the lateral processes of C1 and C2 (red circles). The distance between the odontoid (peg) and the lateral masses of C1 should be equidistant (asterisks). The occi[ital bone and upper incisors should be clear of the odontoid where possible though this can be difficult due to patient positioning as they are normally in collar and blocks. Fracture of the odontoid usually occurs across the base so it is important that this is not obscured by any overlying structures. (Radiology Masterclass, 2019)
The 3rd image shows a lack of alignment of the lateral masses (Whitley et al, 2015).
Caution should be shown as rotation may cause spaces to appear unequal – likely to be rotation if C1 and C2 remain aligned.
C7 information
Has aspects which resemble a T-vertebra
Elongation of the transverse process
Cervical ribs
These can lead to neurological issues down the arms, but in many cases are an incidental finding
Differentiated as the cervical rib forms a joint with the transverse process
NICE guidance on C-spine injury
Within NICE’s Quality Standards [QS74] for Head Injury, it states;
People attending an emergency department with a head injury have a CT cervical spine scan within 1 hour of a risk factor for spinal injury being identified.
Rationale:
Head injuries can be fatal or cause disability if there is damage to the cervical spine that is not identified and treated quickly. A CT cervical spine scan within 1 hour will allow rapid treatment and improve outcomes for people with head injuries that have damaged the cervical spine
What is Paraesthesia?
a burning or prickling sensation, caused by pressure on or damage to nerves; ‘pins and needles’.
NICE guidance and under 16s
If a neurological abnormality attributable to a spinal cord injury is still considered after CT, then perform MRI.
Children (under 16s)
MRI should be performed if there is a strong suspicion of:
Cervical spinal cord injury as indicated by the Canadian C-spine rules and by clinical assessment; or
cervical spinal column injury as indicated by clinical assessment or abnormal neurological signs or symptoms, or both
Consider plain film x-rays in children who do not fulfil the criteria for MRI but clinical suspicion remains
Discuss findings with Consultant Radiologist and perform further imaging, if needed
What to check for on C-spine x-ray?
Alignment checks and measurements to consider when assessing the C-spine for fractures:
Vertebral Contour Lines
Pre-Dental Space
Soft Tissue
Spinous Processes
(C1-C3 Peg View)
