W2 Practical

Question 1

What structures form the anterior and posterior walls of the vertebral canal?

Answer 1

• anterior wall (floor): vertebral bodies, intervertebral discs and posterior longitudinal ligament
• posterior wall (roof): laminae (+ inferior articular processes) and ligamenta flava (connects laminae)

Question 2

Where is the epidural space? What is found in this space and what is its function?

Answer 2

• epidural space - surrounds dural (thecal) sac
• contents
  
  • internal vertebral venous plexus (and epidural fat): cushion to protect the dural sac and its contents (incl. spinal cord)
  • epidural fat: extends into intervertebral foramen + intervertebral veins → cushion emerging spinal nerves
  • recurrent meningeal (sinuvertebral) nerves: supplies posterior longitudinal ligament, adjacent periosteum of vertebral body, outer part of annulus fibrosus, dura mater and blood vessels

Question 3

What are the name of the 3 layers of meninges? Which is outermost and strongest?

Answer 3

• dura mater, arachnoid mater and pia mater
• outermost and strongest: dura mater

Question 4

Between which two layers of meninges is CSF located? What is the name of this CSF-filled space?

Answer 4

• between the arachnoid mater and the pia mater
• the sub-arachnoid space

Question 5

conus medullaris

Answer 5

caudal tip of the spinal cord

Question 6

How much of the vertebral column does an adult spinal cord occupy?

Answer 6

The upper two thirds

Question 7

filum terminale

Answer 7

pia mater that continues in the vertebral canal like a long thing string that anchors the spinal cord inferiorly

Question 8

At which level is the conus medullaris typically located in an adult?

Answer 8

Between L1 and L2

Question 9

cauda equina

Answer 9

• name for all nerve roots inferior to the spinal cord, but still in the vertebral canal
• contained in dural sac ∴ bathed in CSF

Question 10

columns (in the spinal cord)

Answer 10

regions of spinal cord white matter with ascending and descending axons

Question 11

Which constituent of white matter makes it white in colour?

Answer 11

The myelin surrounding the axons

Question 12

spinal cord segment

Answer 12

• gives rise to pair of spinal nerve roots
• innervates exactly one dermatome and myotome on either side of the body

Question 13

Label:

dorsal horn, ventral horn, central canal, ventral and dorsal nerve roots

Answer 13

Question 14

Cell bodies in ventral/anterior horns

Answer 14

lower motor neuron cell bodies - sends axons through ventral nerve roots to control skeletal muscle

Question 15

Where are the thickenings of the spinal cord? Why do these enlargements exist?

Answer 15

• lumbo-sacral and cervical enlargements
• Increased function required, also they are usually the innervation for muscles in the limbs which require more control

Question 16

tract

Answer 16

bundle of axons in the CNS that serve a particular function

note: a white matter colums usually contains multiple tracts (tracts are hard to distinguish by simple inspection)

Question 17

What can a functional pathway be made of?

Answer 17

series of tracts, combined with peripheral nerves

Question 18

anterior, posterior, superior and inferior boundaries of the intervertebral foramina

Answer 18

• anterior: body of vertebra, intervertebral disc
• posterior: zygopophyseal joints and articular processes
• superior: inferior vertebral notch of pedicle of the superior vertibrae
• inferior: superior vertebral notch of pedicle of the inferior vertibrae

Question 19

contents of the intervertebral foramen

Answer 19

• anterior and posterior nerve roots (with dorsal root ganglia)
• dural sleeve (around nerve roots)
• recurrent meningeal nerve
• radicular artery (to nerve roots)
• intervertebral (communicating) veins
• connective tissue (continuous with epidural fat)

Question 20

Which spinal nerves come out above the vertebra of the same name?

Answer 20

C1 to C7

Question 21

Which spinal nerves come out below the vertebra of the same name?

Answer 21

thoracic, lumbar and kinda sacral and coccygeal

Question 22

Which spinal nerve has no named vertebra to correspond with?

Answer 22

C8

Question 23

identify:

• dorsal horn, dorsal root, dorsal root ganglion
• ventral horn, ventral root
• spinal nerve proper, posterior ramus and anterior ramus

Answer 23

Question 24

Which nerve root is motor and which is sensory?

Answer 24

• motor = ventral
• sensory = dorsal

Question 25

What does a dorsal root ganglion contain? Where are DRGs located in relation to vertebrae?

Answer 25

* cell bodies of sensory neurons * dorsolaterally to vertebral body (in intervertebral foramen)

Question 26

What type of fibres does the spinal nerve proper contain?

Answer 26

Mixed sensory and motor nerves

Question 27

What type of fibres are within the dorsal and ventral rami?

Answer 27

mixed sensory and motor nerve fibres

Question 28

What is the recurrent meningeal nerve? What is its function?

Answer 28

* nerve that reroutes from emerging spinal nerve (is mixed) * supplies posterior longitudinal ligament, adjacent periosteum of vertebra, outer part of annulus fibrosus, dura mater (and blood vessels)

Question 29

Draw: roots, trunks, anterior and posterior division, cords and branches of the **brachial plexus**

Answer 29

Question 30

Where is the C2 dermatome?

Answer 30

back of head and neck closest to the jaw

Question 31

What are the dermatomes for lower limb sensation?

Answer 31

L1-S2 (S3 and S4 are more arse)

Question 32

dermatome

Answer 32

area of skin mainly supplied by a single spinal nerve

Question 33

myotome

Answer 33

group of muscles that a single spinal nerve innervates

Question 34

Can you demonstrate the movement of the T1 myotome? Compare this to the T1 dermatome.

Answer 34

* T1 myotome: finger abduction * T1 dermatome: ventral area of forearm (not the hand at all)

Question 35

Which spinal cord segments innervate the upper limb muscles? Which innervate the lower limb muscles?

Answer 35

* upper limb: C5 to T1 (brachial plexus) * lower limb: T12 to S4 (lumber and sacral plexus)

Question 36

(Draw a diagram to demonstrate or) describe the pathway of a LMN leaving the spinal cord to supply the muscle of the forearm.

Answer 36

* possible originating spinal segment: any from C5 to T1 * nerve root: ventral * rami: ventral (anterior) * peripheral nerve: most likely median

Question 37

Explain in general terms the motor and sensory deficits that would be created by damage to a peripheral nerve

Answer 37

* complete loss of motor and sensory nerve to muscles and areas innervated by the peripheral nerve

Question 38

Explain in general terms the motor and sensory deficits that would be created by damage to a spinal nerve

Answer 38

* may not be prominent, especially in nerves involved in nerve plexus * dermatome innervation may be affected, so sensory deficit may be obvious in areas dedicated to a specific dermatome

Question 39

identify: cerebral hemisphere, cerebellum and brainstem Which of these join directly to the cervical spinal cord?

Answer 39

* brainstem joins directly to the cervical spinal cord

Question 40

identify: midbrain, pons and medulla

Answer 40

Question 41

cerebral cortex

Answer 41

continuous sheet of grey matter on the outer layer of each cerebral hemisphere

Question 42

identify lobes of the brain and also their boundaries

Answer 42

missing: * lateral fissure between frontal + parietal lobes and temporal lobe * longitudinal fissure between the two hemispheres of the brain

Question 43

precentral gyrus

Answer 43

* primary motor cortex * from medial to lateral: lower limb, upper limb and then face

Question 44

postcentral gyrus

Answer 44

primary sensory cortex

Question 45

corticospinal tract

Answer 45

important upper motor neuron route that allows key neurons (UMN) in the primary motor cortex to control lower motor neurons in appropriate spinal cord segments

Question 46

At what level of the CNS does the corticospinal tract decussate?

Answer 46

* if lateral corticospinal tract (the majority): decussation below the medullary pyramids * if anterior corticospinal tract, do not decussate until they synapse with LMN

Question 47

stroke

Answer 47

* focal lesion of in CNS * almost always unilateral

Question 48

hemiparesis

Answer 48

* aka hemiplegia, weakness of one side * hemiparetic gait - characteristic abnormality * if lesion is before decussation → affects contralateral limbs

Question 49

If the disability shown here is due to a focal brain lesion, on which side is the lesion?

Answer 49

right side of the brain

Question 50

cerebellum

Answer 50

* second brain: has own cortex and deep nuclei * operations are all below consciousness of cerebrum * compares info from brain and spinal cord → coordinate smooth movement * damage = impaired coordination of limb movements and unsteady gait ataxia (*not weakness though*)

Question 51

basal ganglia

Answer 51

* group of nuclei surrounding the thalamus * important for timing and programming of movements → control balance between action and stillness * does not receive direct sensory feedback

Question 52

How does one palpate for L2 spinal segment?

Answer 52

1. palpate for iliac crest 2. apex of iliac crest lines up (usually) with L4 spinal segment (can feel the spinous process) 3. count two up

Question 53

lumbar cistern

Answer 53

subarachnoid space for lumbar region and cauda equina

Question 54

How does one tell the difference between the anterior median fissure and the posterior median sulcus?

Answer 54

anterior median fissure is deeper, also sometimes the posterior median sulcus is actually hard to define

Question 55

lumbar plexus roots and sciatic nerve roots

Answer 55

* **lumbar plexus:** T12 - L5 * **sciatic nerve roots:** L4 - S3

Question 56

What is the clinical significance of the brainstem?

Answer 56

* primary respiratory centre * many sensory centres reside/pass here * pressing against brainstem → lack of respiratory activity → *DEATH*

Question 57

What is the clinical significance of the honumculus?

Answer 57

stroke signs align with the largest areas of the homunculus

Question 58

Layers from skin to brain

Answer 58

* SCALP * **S**kin * **C**onnective tissue (blood vessels, sensory neurons etc.) * **A**poneurosis * **L**oose connective tissue * **P**eriosteum * Skull (Bone) * three meningeal layers