Back & Vertebral Column Flashcards
Functions of the vertebral column
- Support & Balance
- Protection
- Flexibility
- Shock absorber
How many natural curves of the vertebral column are there?
Morphology of the vertebral column
4
During the pre-natal period, our spine is _-shaped & ______ ______
During the pre-natal period, our spine is C-shaped (picture) & anteriorly concave
The spine is made of __ to __ vertebrae
The vertebrae in the lower portion of the column have larger bodies than those in the upper portion to….
The spine is made of 32 to 33 vertebrae
…to better support the increased weight.
Spine is divided into _ regions
What are the regions & levels?
The spine is divided into 5 regions
Cervical | C1 to C7
Thoracic | T1 to T12
Lumbar | L1 to L5
Sacrum & Coccyx | S1 to S5 | Cox1 to Cox3
Superior View of a cervical vertebra
Lateral View of a cervical vertebra
Ligamentum nuchae
The ligamentum nuchae is a large median ligament composed of tendons and fascia. It covers the spines of C1 to C7 vertebrae.
Extends from the external occipital protuberance on the skull and median nuchal line, to the spinous process of C7
The Atlas (C1)
[Atypical Cervical Vertebrae)
The Axis (C2)
[Atypical Cervical Vertebrae)
The odontoid process, or dens is something significant in comparision to other cervical vertebrae
The joint between the superior facet & the occipital bone
Atlanta occipital joint
Flexion and extension of the neck
What does the dens act as?
The dens acts as a pivot that allows the atlas + the above occipital bone + head to rotate on the axis, side to side.
All Atypical Vertebrae
Typical vs Atypical
C1, C2, C7, T1, T9, T10, T11, T12, and L5 are the atypical vertebrae
Structure of a typical thoracic vertebra
Structure of a typical lumbar vertebra
The sacrum & coccyx
The sacrum & coccyx Posterior view
The vertebrae: a short summary
How the vertebrae articulate
The intervertebral discs
- They account for around 20-30% of the total spine length
- Vertebral discs provide strong attachments between vertebral bodies
- They serve as shock absorbers
- The discs are formed by two areas; an outer anulus fibrosus and an inner nucleus pulposus
The filum terminale (FT)
Is a fibrous band that extends from the conus medullaris to the periosteum of the coccyx.
Functions: This string like structure anchors the spinal cord to the sacrum and sacral region
The spinal cord
- A long, thin, tubular structure made up of nervous tissue
Extends from the medulla oblongata in the brainstem to the lumbar region of the vertebral column (approximately L1)
From here a series of spinal nerves branch off to form a structure called “cauda equina”, which means “horse’s tail”
The central canal
The central canal hosts Cereberal Spinal Fluid (CSF)
CSF: Clear and colourless fluid in brain and spinal cord produced by specialised cells in the ventricles of the brain and is absorbed by arachnoid granulations (found in the superior saggital sinus)
Why is the vertebral column an ideal spot for cancer to spread?
It is because the vetebral column is highly porous and rich in blood vessels
The spinal cord in the spinal canal
The delicate neural tissue of the spinal cord is protected, as for the brain, by 3 layers of meninges (outer to inner)
- Dura mater
- Arachnoid mater
- Pia mater
These are continuous with the cranial meninges that protect the brain
The epidural space
Area between the dura mater & the vertebral wall
Contains connective and adipose tissues | blood vessels
Site for anaesthetic injections
Dura terminating near coccyx with filum terminalae (see diagram)
Know where pia and dura terminate inferior end of spine*
Arachnoid Mater
Most elastic
Formed by elastic collagen fibres
Between the Arachnoid membrane & Pia mater
The subarachnoid space
Continuous with intracranial subarachnoid space
Relatively large space containing approx. half of total CSF
When spinal nerve ends at L1/L2, the subarachnoid space distal to this forms an area called the…
Lumbar cistern
The cistern is an enlargement of the subarachnoid space in the dural sac, distal to the conus medullaris. It contains cerebrospinal fluid & the nerve roots of the cauda equina ideal
Ideal area for lumbar puncture
What does filum terminale anchor to?
The spinal cord is anchored distally by the filum terminale, a fibrous extension of the pia mater anchoring the spinal cord to the coccyx.
Conus medullaris
The filum terminale (“terminal thread”) is a delicate strand of fibrous tissue, about 20 cm in length, proceeding downward from the apex of the conus medullaris. It is one of the modifications of pia mater.
{Where the filum terminale starts}
The denticulate ligament
Comes off the pia mater and laterally anchors the spinal cord to the meninges
How many spinal nerves in total?
There are 31 pairs of spinal nerves
(8 cervical | 12 thoracic | 5 lumbar | 5 sacral | 1 coccygeal)
Why do we have 7 Cervical Vertebraes but 8 Cervical nerves
The first pair pass between the skull and C1 so we possess 7 cervical vertebrae but 8 cervical nerves
Movements of the spine
The anterior longitudinal ligament (ALL)
{The anterior ligament}
Purpose: Allow the flexion and extension of the spine while keeping the bones aligned
Arises from the occipital bone
Structure:
- Traverses (makes up/travels) the entire length of the spine along the anterior aspect of the body of the vertebrae and ends on the antero-superior portion of the sacrum
- It broadens as it descends.
The posterior longitudinal ligament (PLL)
{The posterior ligament}
Purpose: Allow the flexion and extension of the spine while keeping the bones aligned
Arises from the back of the axis (C2) body
Structure:
- Travels downward & attaches posteriorly to the vertebral bodies and intervertebral discs, attaching to the back of the sacrum.
- It narrows as it descends.
The interspinous ligament
{The posterior ligament}
Purpose: Allow the flexion and extension of the spine while keeping the bones aligned
- Joins the spinous processes
- Fuses with the strong, supraspinous ligament
The supraspinous ligament
{The posterior ligament}
Purpose: Allow the flexion and extension of the spine while keeping the bones aligned
- Joins the tips of the spinous processes.
The ligamentum flavum
{The posterior ligament}
Purpose: Allow the flexion and extension of the spine while keeping the bones aligned
- A paired ligament which runs between the adjacent lamina of the vertebral bodies
It is a paired, yellowish, elastic ligament.
- It starts off relatively thin in the cervical spine to progressively become thicker in the lumbar spine
The intertransverse ligaments
{The posterior ligament}
Purpose: Allow the flexion and extension of the spine while keeping the bones aligned
- Join transverse processes of adjacent vertebrae
- These are very thin fibrous cords
The ligamentum nuchae
{The posterior ligament}
Purpose: Allow the flexion and extension of the spine while keeping the bones aligned
A large median ligament composed of tendons & fascia located between the posterior muscles of the neck
It spans from the external occipital protuberance and median nuchal line to the spinous process of C7, attaching all the posterior tips of C1 to C6 spinous processes.
It is an extension of the supraspinous ligament
It is thick & strong, limiting hyperflexion of the neck.
Ligaments of the spine
(do questions for this later)
- There are multiple ligaments in the spine. What do ligaments hold together?
- What is a ligament composed of?
- What function do ligaments play?
- Bone
- Skeletal ligaments are defined as dense bands of collagenous tissue (fibres) that span a joint.
- Increase stability of the spine, restrict movements that may damage the joint
The muscles of the back
What are the 2 superficial intrinsic muscles that rotate the head & extend the neck?
The splenius capitis & splenius colli (or splenius cervicis)
Function: rotation of the head (same side); extension of the neck; also involved in lateral flexion of the neck (same side).
What muscle is being circled in the cadaver picture?
Splenius capitis
How many intermediate intrinsic back muscles are there?
Tell me about them.
3
Spinalis, Longissimus & Iliocostalis,
They are quite long, large muscles running along the back of the spine. Together these muscles form a column - erector spinae.
Function
They all act unilaterally to cause lateral flexion of the vertebral column. They also contract bilaterally to extend the vertebral column and head. In addition, the connection with the pelvis also helps stabilise the column.
The deep intrinsic muscles
The deep intrinsic muscles are located underneath the erector spinae, and are known collectively as the transversospinales
They are a group of muscles associated with the transverse and spinous processes of the vertebral column
Function
Stabilise the spine by holding together the vertebrae; the semispinalis extend (bilateral contraction) & rotate (unilateral contraction) the head, neck and trunk
Interspinales
There are minor deep intrinsic muscles or segmental muscles
Spans between adjacent spinous processes. Acts to stablise the vertebral column
Intertranversari
There are minor deep intrinsic muscles or segmental muscles
Spans between adjacent transverse processes. Acts to stablise the vertebral column.
Levatores costarum
There are minor deep intrinsic muscles or segmental muscles
Originates from the transverse processes of C7-T11, and attaches to the rib immediately below. Acts to elevate the ribs.
Honourable Mentions
