Week 9 - Spinal Cord

Question 1

What are the 3 embryological tissues?

Answer 1

Ectoderm
Mesoderm
Endoderm

Question 2

Describe the process of neurulation.

Answer 2

Notochord and neuroepithelium induce the formation of the neural plate.
The neural plate begins to fold creating the neural groove.
Groove closes to form neural tube.
Neural tube is open at both ends forming an anterior and posterior neuropore.

Question 3

What are the primary and secondary brain vesicles?

Answer 3

Prosencephalon - Telencephalon and Diencephalon.
Mesencephalon.
Rhombencephalon - Metencephalon and Myelencephalon.

Question 4

What do the secondary vesicles form?

Answer 4

Telencephalon = Cerebrum and Lateral Ventricles.
Diencephalon = Thalamus, eye cup and 3rd ventricle.
Mesencephalon = Midbrain and cerebral aqueduct.
Metencephalon = Pons, cerebellum and 4th ventricle.
Myelencephalon = Medulla and 4th ventricle.

Question 5

What is Anencephaly?

Answer 5

Cranial/anterior neuropore fails to close.
No brain vesicles develop.
Death.
Increased in alpha fetoprotein.

Question 6

What is the difference between spina bifida occulta, meningocele and menigomyelocoele?

Answer 6

Occulta = Vertebral arch fails to fuse but spinal cord is intact. Usual tuft of hair present at base of spine. NO SYMPTOMS.
Meningocele = Meninges protrude.
Meningomyelocoele = Most sever form where spinal cord and meninges protrude - causes paralysis below level of protrusion.
Both ‘ocele’ cause increase in alpha fetoprotein and skin overlies the defect.

Question 7

Name the primary and secondary curvatures of the spine.

Answer 7

Thoracic
Sacrococcygeal
Lumbar
Cervical

Question 8

What pathologies are involved in the curvatures of the spine?

Answer 8

Kyphosis = Increase posterior thoracic curve due to osteoporosis.
Lordosis = Increased anterior lumbar curve.
Scoliosis = Lateral curvatures and twisting.

Question 9

Name the ligaments of the spinal cord and their locations.

Answer 9

Anterior Longitudinal - Anterior to the vertebral body.
Posterior Longitudinal - Between vertebral body and spinal cord.
Supraspinous - Along spinous processes.
Infraspinous - Between spinous processes.
Denticulate - Between dorsal and ventral roots of spinal cord. Formed from PIA MATER.
Ligamentum Flavum - Yellow ligament between the lamina of adjacent vertebrae.

Question 10

What structure forms the anterior median fissure and what roots are present there?

Answer 10

Basal Plate

Motor roots

Question 11

What structure forms the posterior median sulcus and what roots are present there?

Answer 11

Alar plate

Sensory roots

Question 12

What are the enlargements of the spinal cord and why are they present?

Answer 12

Cervical = brachial plexus
Lumbar = lumbrosacral plexus

Question 13

Where does the spinal cord end?

Answer 13

L1/L2

Question 14

Where does the subarachnoid space end?

Answer 14

S2

Question 15

What is the space called between where the spinal cord ends and the subarachnoid space ends and what is its purpose?

Answer 15

Lumbar cistern

Where needle is placed in epidural to paralyse the nerves during childbirth or surgery.

Question 16

What are the 3 important structures at the end of the spinal cord?

Answer 16

Cauda equina = lumbrosacral roots.
Conus medulalris = tapered end of spinal cord.
Filum Terminale = Tube of pia mater that anchors spinal cord to sacrum.

Question 17

What is different about the thoracic spinal cord structure?

Answer 17

Has a lateral horn present.

Question 18

What are dermatomes and myotomes?

Answer 18

Dermatomes = areas of innervation of skin from spinal nerves.
Myotomes = innervation of groups of muscles from spinal cord.

Question 19

What are the main arteries involved in supplying the spinal cord and where do they originate?

Answer 19

Anterior spinal artery = Ventral horns and motor tracts.
Posterior spinal artery = Dorsal horns and sensory tracts.
Radicular = Spinal N roots.
Anterior and posterior spinal branch from basilar artery.
Radicular branch form anterior and posterior spinal.

Question 20

What is the role of the dorsal column medial lemniscus pathway?

Answer 20

Touch and proprioception.

Question 21

What is the pathway of the DCML?

Answer 21

Dorsal Root Ganglia
Dorsal Column
Fasciculus/Nucleus Gracilis and Cuneatus.
Decussation to medial lemniscus.
VPL of thalamus.
Posterior Internal Capsule.
Primary Somatosensory Cortex.

Question 22

What is the role of the spinothalamic pathway?

Answer 22

Pain and temperature perception.

Question 23

What is the pathway of the spinothalamic tract?

Answer 23

Dorsal root ganglia.
Lissauers tract.
Decussate at white anterior commissure.
VPL of thalamus
Post internal capsule.
Primary somatosensory cortex.

Question 24

What are the 4 spinocerebellar tracts and what are they involved in?

Answer 24

Dorsal
Ventral
Cuneo
Rostral
All involved in fine motor control.
D and V both lower limb.
C and R both upper limb.

Question 25

What is the corticospinal tract involved in?

Answer 25

Conscious and voluntary movement.

Question 26

What are the differences between UMN and LMN damage?

Answer 26

UMN = spasticity and change in muscle tone, increased tendon reflex/hyperreflexia, loss of voluntary control.
LMN = Arryflexia/decreased tendon reflex, muscular atrophy and fasciculations.

Question 27

What happens in a cerebellar lesion and what is the difference between a vermis lesion and a hemispheric lesion?

Answer 27

Damage to SAME side of body.
Anterior Lobe Vermis = Affects lower limbs - gait problems.
Hemispheric = Affects upper limb - issues with rapid movement, hypotonia, ataxia, intention tremor.

Question 28

What happens in a lesion in the basal ganglia and what are the differences between the direct and indirect pathway?

Answer 28

Damage to the OPPOSITE side of the body. Involuntary Movements.
Indirect = Too much movement, no inhibition - HUNTINGTONS.
Direct = Too little movement, no activation - PARKINSONS.