Neuroanatomy 5 Flashcards
What are some functions of the vertebral column?
Protecting the spinal cord
Supporting the head and torso
Providing attachments for muscles and ribs
Site of haematopoesis
How many vertebrae are there in each segment of the VERTEBRAL COLUMN?
cervical 7
thoracic 12
lumbar 5
sacral 5
coccygeal 4 fuse to form the coccyx
What is a kyphosis?
What is a lordosis?
kyphosis - outwards curvature of the spine
lordosis - inwards curvature
Where are the curvatures of the spine?
Cervical lordosis in the neck
thoracic kyphosis in the upper back
Lumbar lordosis in the lower back
What are the common features of the vertebrae? Draw a picture
Body -
Pedicle -
Lamina -
Spinal canal -
Transverse processes -
What is the body of the vertebrae?
Supports the weight of the vertebrae above it
Located most anteriorly
Neighbouring ones are separated by intervertebral discs
What is the pedicle of the vertebrae?
Connects the body to the rest of the vertebra
Stems posteriorly from vertebral body
Forms the lateral wall of the spinal canal
What is the lamina of the vertebrae?
The part that forms the posterior wall of the spinal canal
The spinous process stems from the lamina
What is the spinal canal of the vertebrae?
Hole bordered by the body, pedicle, lamina
Spinal cord travels within it
What is the transverse process of the vertebrae?
Lateral protrusions of the vertebrae at the junction between pedicle and lamina
Provide an attachment for muscles
What is the articular process of the vertebrae?
Vertical protrusions of the vertebrae - 2 each
Provide a site of attachment to the vertebrae above and below
(facet joints - synovial articulations)
What is the intervertebral foramina of vertebrae?
Holes at the side of each vertebra
Formed by the spaces between the bodies and pedicles of neighbouring vertebrae
The spinal nerves leave the cord through these
Which 2 vertebrae have unique features? What are their names?
C1 - atlas - articulate directly with occipital bone - joint allows nodding of head
- space where the vertebral body should be, within the vertebra
- no spinous process
C2 - axis -
- body protrudes vertically upwards - odontoid process - takes place of body in the atlas so it can spin around axis
- joint allows turning of head (atlanto-axial joint)
Which joint allows us to turn our head?
What type of joint is it?
Atlanto-axial joint
Pivotal joint
Atalas vertebra(C1) spins around the axis vertebra (C2)
Which cervical vertebrae are different to the others?
C1 - atlas
C2 - axial
C7 - lacks transverse foramina and has a more prominent spinous process
What are the features of the (12) thoracic vertebrae?
Become increasingly larger from superior to inferior, most inferior support more weight
Unique - additional articular surfaces for ribs
Spinous processes are long, sharp and point downwards (protect spinal canal more effectively)
What are the identifiable features of cervical vertebrae?
Smaller body than other types (they support less weight)
Transverse foramina - hole in transverse processes that vertebral arteries travel through
Bifid spinous process - ‘two pronged’
How is C7 different to other cervical vertebrae?
Why is it sometimes called the ‘vertebra prominens’?
No transverse foramina
the spinous process is much more prominent, usually the most superior process you can palpate through the skin
This is why it is called ‘vertebra prominens’
spinous process might not be bifid
What are the distinctive features of the (5) lumbar vertebrae?
Largest individual vertebrae
VERY large vertebral bodies
Transverse processes project laterally, provide attachment for additional muscles
Spinous processes are large and relatively short and rectangular (comp to thoracic)
What are the features of the sacrum?
5 sacral vertebrae fused to form the sacrum
Large triangular shaped bone
Located in the central posterior part of the pelvis
Articulates with the pelvis at the sacroiliac joints
Sacral promontory - anterior prominence at the top of the sacrum
What is the coccyx?
4 bones fused together
Attaches at the inferior aspect of the sacrum
compare the table with the paragraphs and write better flashcards :)
What is the purpose of intervertebral discs?
Strong, fibrocartilaginous structures
Withstand compression forces while also allowing flexibility and movement between vertebra
What is the structure of the intervertebral discs?
Nucleus pulposus - central gelatinous core
Annulus fibrosus - concentric rings of collagen surrounding the nucleus pulposus
Separated from neighbouring vertebral bodies by thin layer of hyaline cartilage on the surface of the vertebral bodies
What are the type of joints in the vertebral column?
Pivot joint - atlanto-axial joint
Secondary cartilaginous joint - between vertebrae, involving intervertebral discs
What joints are the intervertebral discs involved in?
bone - hyaline cartilage - fibrocartilage - hyaline cartilage - bone
A secondary cartilaginous joint
What do ligaments do in the spinal column?
What are the 5?
Help maintain upright posture and prevent hyperflexion/hypertension injuries
Anterior longitudinal ligament
Posterior longitudinal ligament
Ligamentum flavum
Interspinous ligament
Supraspinous ligament
What and where is the anterior longitudinal ligament?
Ligament
In the vertebral column
Along the anterior surfaces of the vertebral bodies
What and where is the posterior longitudinal ligament?
Ligament
In the vertebral column
Along the posterior surfaces of the vertebral bodies, but anterior to the spinal canal
What and where is the ligamentum flavum?
Ligament
In the vertebral column
Along the inside of the laminae (posterior to the spinal canal)
‘Flavum’ - yellow due to amount of elastin protein within it
What and where is the interspinous ligament?
Ligament
In the vertebral column
Between the spinous processes
think loose cheese texture
Might not be continuous
What and where is the supraspinous ligament?
Ligament
In the vertebral column
along the very tips of the spinous processes
runs longitudinally?
What are the paraspinal muscles?
Support the vertebral column
One group - erector spinae forms a column either side of the spinous process
contribute to upright posture, often can be palpated either side of the lumbar spine while standing
disc herniation
lumbar puncture
CSF from subarachnoid space, lumbar canal
Lower than L2 - cauda equina nerves pushed out the way not damaged
Aim for L4/L5 space - in line with iliac crests (intercristal plane)
Patient lies in foetal position and pushes out lower back
How are spinal nerves named?
Named by the level at which they leave the spine
Leave ABOVE their corresponding vertebrae up to C7
C8 leaves below C7 vertebra
From then, all remaining leave from BELOW their corresponding vertebra
Only 1 pain of coccygeal spinal nerves
How many spinal nerves are there?
31
C - 8 ( more nerve than vertebrae)
T - 12
L - 5
S - 5
Coccyx - 1
What is the conus medullaris?
Where the spinal cord tapers off into a cone shape. It is the cone shape
Approx L1/L2 it terminates the spinal cord
Where does the spinal cord terminate?
Approx L1/L2
Tapers off into conus medullaris, terminates
Dura and arachnoid meninges continue, pia mater forms filum terminale
The cauda equina continues down spinal canal
What is the filum terminale? (spinal cord)
Pia mater thickens after spinal cord terminates
Thin strand of fibrous tissue
Continues down to the coccyx, where it tethers the spinal cord in place
What is the cauda equina? (spinal cord)
Mass of spinal nerves, given off before the spinal cord terminates that are yet to leave
L3-L5, S1-S5, Co1
Mass of spinal nerves resembles a horse’s tail… hence cauda equina
Which spinal nerves are in the cauda equina?
L3-L5
S1-S5
Co1
What are the 2 roots in each spinal nere?
Dorsal and ventral roots that stem from the dorsal and ventral aspects of the spinal cord respectively
What is the dorsal root of the spinal nerves?
Carries sensory fibres INTO the spinal cord (enter through dorsal horn)
Contains the dorsal root ganglion (which is outside the vertebral column)
What is the ventral root of the spinal nerves?
Carries motor fibres OUT of the spinal cord - pass through ventral horn
Doesn’t have a ganglion
Sympathetic fibres also leave the cord via the ventral root
What is the structure of the grey and white matter in the spinal cord?
Grey matter - ‘H’ shape in the centre - two dorsal horns and two ventral horns
White matter tracts around the outside
What letter does a spinal nerve represent? Why?
X
Two roots that join and then separate pretty soon after into rami
What do spinal nerves divide into?
Dorsal rami - carries sensory and motor supplying dorsal structures
Ventral rami - LARGER - carries sensory and motor fibres to ventral structures
Thoracis ventral rami are renamed the intercostal nerves
What type of nerve fibres do ventral and dorsal rami carry?
both carry BOTH types - motor AND sensory
What are the pathways like in ascending sensory pathways? (spinal cord)
Typically 3 neurones in the pathway
1st order - receptor to CNS with cell body in dorsal root ganglion
2nd order - from spinal cord/brainstem to thalamus
3rd order - thalamus to somatosensory cortex
What are the pathways like for descending motor pathways? (spinal cord)
Typically 2 neurones
1st order(upper motor neurone) - motor cortex to ventral horn of the spinal cord
2nd order(lower motor neurone) - spinal cord to target muscle
What is decussation in the spinal cord?
Where (most) of the ascending/descending tracts cross over to the contralateral side
Not all do it
Cross at various levels
Which is larger, dorsal or ventral ramus?
Ventral
What are spinal tracts?
Bundles of axons are organised into vertical columns within the peripheral white matter of the cord
What 4 groups of spinal tracts are covered in anatomy?
Lateral corticospinal tract
Spinothalamic tract
Spinocerebellar tract
Dorsal columns
- Fasciculus gracilis (DCML)
- fasciculus cuneatus
For the dorsal columns medial lemniscus what is…
- the type of fibres
- position in an axial slice
- place of decussation
- where do the 1st order neurones originate from?
- where do the 2nd/3rd order neurones synapse?
- What do they carry information about?
- sensory (so ascending)
- located on dorsal section of white matter in spinal cord
- within the medulla, after the synapse
- fasciculus gracilis (medial) - lower limbs
fasciculus cuneatus(lateral) - upper limbs - gracile and cuneate nuclei > synapse in thalamus > via internal capsule to primary somatosensory cortex (parietal lobe)
- fine touch, two point discrimination, vibration and proprioception
Why is the dorsal column medial lemniscus in the spinal column called this?
It is made up of the dorsal columns in the spinal cord (fasciculus gracilis and cuneatus)
And the medial lemniscus (after they synapse with gracile/cuneate nuclei, decussate and continue to thalamus)
What is the medial lemniscus? (DCML spinal cord)
Part of the DCML tract
After the two distinct dorsal tracts synapse with their respective nuclei, they decussate and continue contralaterally up to the thalamus where they synapse again
this part is called the medial lemniscus
How many orders of neurones does the DCML in the spinal cord have?
3
1st - limb to medulla
2nd - medulla to thalamus
3rd - thalamus to primary somatosensory cortex
For the spinothalamic tract what is…
- the type of fibres
- position in an axial slice
- place of decussation
- where do the 1st order neurones originate from?
- where do the 2nd/3rd order neurones synapse?
- what information does the tract carry?
- sensory (so ascending)
- antero-laterally (around side of ventral horns)
- decussate in the spinal cord, usually after 1-2 vertebral levels
- All over, enter through dorsal root synapse in the horn
- Dorsal horn > thalamus > via internal capsule to primary somatosensory cortex (parietal lobe)
- crude touch, pain, temperature (check that it may be dodgy)
How many orders of neurones does the spinothalamic tract in the spinal cord have?
3
1st - synapses in the dorsal horn
2nd - decussates, spinal cord to thalamus
3rd - thalamus to somatosensory cortex
For the lateral corticospinal tract what is…
- the type of fibres
- position in an axial slice
- place of decussation
- where do the 1st order neurones originate from?
- where do the 2nd/3rd order neurones synapse?
- information it transmits?
- motor (descending)
- located laterally (immediately anterior to dorsal horns)
- medulla at medullary pyramid level
- Upper motor neurones from motor cortex through internal capsule
- Synapse with 2nd in ventral horn, leave via ventral root
- carry motor impulses
How many orders of neurones does the lateral corticospinal tract have?
2
1st - Motor cortex via internal capsule to ventral horn
2nd - Ventral horn through ventral root to target muscle
For the anterior and posterior spinocerebellar tracts what is…
- the type of fibres
- position in an axial slice
- place of decussation
- what information does it carry?
- sensory tracts (ascending)
- most laterally (curve around outline at the sides)
anterior decussation… - 1 - at level of entry into the cord
2 - as soon as it enters the cerebellum through superior peduncle
so terminates ipsilaterally
posterior decussation… - DOESN’T, terminates ipsilaterally also
- unconscious proprioceptive information to the cerebellum
What is the difference between the anterior and posterior spinocerebellar tracts?
Anterior dessucates twice - at level of entry then as it enters cerebellum (cerebellar peduncle)
Posterior doesn’t decussate
Both enter ipsilaterally to starting point
Brown-Sequard syndrome… what is it?
Damage to one side of the cord only (hemisection)
Rare injury in practice
Damage on left side - descending lateral corticospinal tract left side damage, DCML ascending left side damage, ascending spinothalamic damage ‘effect’ on right side
What symptoms would Brown-Sequard syndrome present with if the lesion was on the left?
Loss of motor control of muscles on the left
Loss of 2 point discriminative touch, vibration and proprioception sensation on the left
Loss of pain and temperature sensation on the right from one or 2 levels below lesion
Where do each of the tracts decussate?
DCML?
Spinothalamic
Lateral Corticospinal
Anterior and Posterior spinocerebellar tracts
- medulla
- 1-2 levels above entry to the cord
- medullary pyramids
- anterior - at level of entry AND at entry to cerebellum through superior cerebellar peduncle
- posterior - doesn’t decussate
What information do each of the spinal tracts carry?
- DCML - 2 point touch discrimination, vibration, proprioception
- Spinothalamic -
LOOK IT UP
From where do the sympathetic nerves leave the spinal cord grey matter?
Which root do they take to leave the cord?
Where do they go after this?
T1 - L2 levels of the spinal cord
Leave by ventral root alongside motor fibres towards the sympathetic trunk
In trunk they either synapse at that level, travel up/down sympathetic trunk to synapse at another level or pass through it as a splanchnic nerve
The ligamentum flavum connects which part of the vertebrae together? 2
Which arteries supply the spinal cord?/6
What deficits would a lesion in the right side of the spinal cord only, cause? 7a
What deficits would a lesion in the posterior third of the spinal cord bilaterally, cause?/7b
What deficits would a lesion in the left sided the dorsal root cause? /7c
