NSSB TBL 2 - Spinal Cord and Peripheral Nervous System

What vertebral level does the spinal cord end in adults?

L1–L2 (conus medullaris)

What vertebral level does the dural sac end?

S2

What structure anchors the spinal cord inferiorly?

Filum terminale

What structure laterally stabilises the spinal cord?

Denticulate ligaments

What is the cauda equina composed of?

Lumbar and sacral nerve roots (LMN fibres)

Which spinal cord enlargement innervates the upper limb?

Cervical enlargement (C5–T1)

Which spinal cord enlargement innervates the lower limb?

Lumbosacral enlargement (L2–S3)

What is the central canal?

A CSF-filled channel running through the spinal cord

What is the function of the dorsal horn?

Sensory processing

What is the function of the ventral horn?

Motor neuron output (LMN cell bodies)

Where are sympathetic preganglionic neurons located?

Lateral horn (T1–L2)

Which tract carries vibration and proprioception?

Dorsal columns

Which tract carries pain and temperature?

Spinothalamic tract

Which tract carries motor UMN fibres?

Lateral corticospinal tract

Where do corticospinal fibres decussate?

Medullary pyramids

What sensation is lost in dorsal column damage?

Vibration and proprioception

What sensation is lost with spinothalamic damage?

Pain and temperature

Which lesion produces ipsilateral dorsal column loss below the lesion?

Brown-Séquard syndrome

Which lesion produces contralateral pain and temperature loss below the lesion?

Brown-Séquard syndrome (spinothalamic tract)

Which lesion causes bilateral cape-like loss of pain and temperature?

Syringomyelia

What fibres are first affected in syringomyelia?

Decussating spinothalamic fibres (anterior white commissure)

Is vibration sense preserved in syringomyelia?

Yes (dorsal columns intact)

What motor neurons are affected in advanced syringomyelia?

Anterior horn cells (LMN)

What is the clinical presentation of LMN hand involvement in syringomyelia?

Weakness, wasting, fasciculations

What is the conus medullaris?

Terminal end of the spinal cord

What are the typical symptoms of conus medullaris syndrome?

Early bladder dysfunction, saddle anaesthesia, mixed UMN/LMN signs

What is cauda equina syndrome?

Compression of lumbosacral nerve roots (LMN lesion)

What is the hallmark of cauda equina syndrome?

Saddle anaesthesia

Which condition presents with urinary retention and LMN leg weakness?

Cauda equina syndrome

Is cauda equina syndrome an emergency?

Yes—requires urgent decompression

Which spinal level is most commonly involved in disc herniation causing cauda equina?

L4–L5

What type of motor signs occur below a complete spinal cord transection?

UMN signs below the lesion after spinal shock resolves

What type of motor signs occur at the level of the lesion in spinal cord injury?

LMN signs (ventral horn damage)

What is spinal shock?

Temporary flaccid paralysis and areflexia after acute cord injury

What is the typical timeline of spinal shock?

Days to weeks before reflexes return

What returns first after spinal shock?

Babinski sign (UMN)

What is a dermatome?

Area of skin supplied by a single spinal nerve

What is a myotome?

Muscle group supplied by a single spinal nerve root

What are the dorsal roots responsible for?

Sensory input

What are the ventral roots responsible for?

Motor output

What type of neurons reside in the dorsal root ganglion?

Pseudounipolar sensory neurons

What does the dorsal ramus supply?

Deep back muscles and posterior skin

What does the ventral ramus supply?

Limbs and anterolateral trunk

Where is the spinal cord largest?

Cervical region (most white matter)

Where is the spinal cord smallest?

Sacral region

Which tract conveys fine touch information?

Dorsal columns (gracile and cuneate fasciculi)

What is the gracile fasciculus?

Medial dorsal column carrying lower limb sensory info

What is the cuneate fasciculus?

Lateral dorsal column carrying upper limb sensory info

What artery supplies the anterior two-thirds of the spinal cord?

Anterior spinal artery

What artery supplies the dorsal columns?

Posterior spinal arteries

What is anterior spinal artery syndrome?

Infarction causing bilateral motor + pain/temp loss with preserved dorsal columns

What is preserved in anterior spinal artery syndrome?

Vibration and proprioception

What are symptoms of posterior column damage?

Ataxia, positive Romberg, loss of vibration sense

What is the Romberg test used to assess?

Proprioception (dorsal column function)

What is Brown-Séquard syndrome?

Hemisection of the spinal cord

What are key signs of Brown-Séquard?

Ipsilateral motor + dorsal column loss, contralateral pain/temp loss

What spinal cord disease causes painless burns on hands?

Syringomyelia

What spinal condition worsens in extension and improves in flexion?

Lumbar spinal stenosis

What is neurogenic claudication?

Leg pain from lumbar stenosis relieved by spinal flexion

Which structure is compressed in spinal stenosis?

Spinal canal/neural foramina narrowing

What are the symptoms of cervical myelopathy?

UMN leg signs + hand clumsiness + gait disturbance

Which tract damage causes spasticity?

Lateral corticospinal tract

Which tract damage causes loss of proprioception?

Dorsal columns

Which pathway transmits crude touch?

Anterior spinothalamic tract

Which reflex is missing with S1 root damage?

Ankle jerk

Which reflex is missing with L4 root damage?

Knee jerk

Which reflex is missing with C5–C6 damage?

Biceps reflex

Which reflex is missing with C7 damage?

Triceps reflex

Which descending tract modulates reflex activity?

Corticospinal tract

What type of lesion produces hyperreflexia?

UMN lesion

What type of lesion produces fasciculations?

LMN lesion

Where are LMNs located in the spinal cord?

Ventral horn

Which horn contains motor neurons?

Ventral horn

Which horn contains sensory relay neurons?

Dorsal horn

What is the function of interneurons in the spinal cord?

Coordinate reflexes and integration

What does the spinocerebellar tract transmit?

Unconscious proprioception

What type of lesion produces ipsilateral limb ataxia?

Spinocerebellar tract lesion

What sensation is lost first in central cord syndrome?

Pain and temperature

What is central cord syndrome?

Cervical canal injury causing arm > leg weakness

Which condition causes arm weakness more than leg weakness?

Central cord syndrome

What is Lissauer’s tract?

Pain and temp fibres ascending/descending 1–2 segments

Why is pain/temp loss often below the lesion?

Spinothalamic fibres ascend before crossing

Which spinal tract is affected by a lesion causing contralateral pain loss?

Spinothalamic tract

Which spinal tract is affected by a lesion causing ipsilateral vibration loss?

Dorsal columns

What fibre type is selectively damaged in diabetic neuropathy?

Distal small and large fibres (but this belongs to Chunk 3—avoid)

Which tract decussates in the spinal cord?

Spinothalamic tract

Which tract decussates in the brainstem?

Corticospinal tract

Where do dorsal column fibres synapse before crossing?

Nucleus gracilis & cuneatus (medulla)

What is the somatotopy of the dorsal columns?

Legs medial (gracile), arms lateral (cuneate)

What is the somatotopy of the corticospinal tract?

Arms medial, legs lateral

What is the somatotopy of the spinothalamic tract?

Legs lateral, arms medial

Which spinal column is most vulnerable in vitamin B12 deficiency?

Dorsal columns

What is the hallmark of dorsal column dysfunction?

Positive Romberg test

What is the hallmark of corticospinal dysfunction?

Spasticity + hyperreflexia

What is the hallmark of spinothalamic dysfunction?

Loss of pain and temperature

What is the function of the cervical enlargement?

Upper limb innervation

What is the function of the lumbar enlargement?

Lower limb innervation

What is the function of the conus medullaris?

Terminates cord; gives rise to cauda equina

What is the most common cause of spinal cord compression?

Cervical spondylosis

Which root carries sensory signals?

Dorsal root