BACK AND AUTONOMIC NERVOUS SYSTEM

Question 1

VERTEBRAL COLUMN

Embryology

Answer 1

• week 4 → sclerotome cells of somites (mesoderm)
• migration cells → surround notochorda and spinal cord + proliferation
• vertebra → caudal part of one sclerotome + cephalic part of another

Question 2

VERTEBRAL COLUMN

Generalities

Answer 2

• spinal cord protection + movements + weight distribution to lower limbs
• 32-32 vertebrae
  
  • 7 cervical
  • 12 thoracic
  • 5 lumbar
  • 5 sacral
  • 3-4 coccygeal
• 31 spinal nerves
• ligaments + synovial articulations + intervertebral disk

Question 3

VERTEBRAL COLUMN

Typical Vertebrae

Answer 3

Question 4

VERTEBRAL COLUMN

Intervertebral disk

Answer 4

• 25% of the lenght of the vertebral column
• numberd by the vertebral body above
• allows limited movement between vertebral bodies
• composition:
  
  • anulus fibrosus - concentric rings of fibrocartilage and fibrous connective tissue
  • nucleus pulposus - shock absorber, inner soft tissue, postnatal remnant of the notochorda

Question 5

VERTEBRAL COLUMN

Ligaments and Intervertrebral Foramen

Answer 5

• longitudinal ligaments → firmly attached to the intervertebral disks and vertebral bodies
  
  • anterior - stronger, prevents hyperextension and are involved with “whiplash” accidents
  • posterior - in the vertebral canal, limitis flexion and are involved with herniation
• intervertebral foramen: passage of the spinal nerve
  
  • anterior - vertebral body + disk
  • posterior - articulation
  • superior/inferior - pedicles

Question 6

VERTEBRAL COLUMN

Clinical Correlate: Herniated Disk

Answer 6

• nucleus pulposus herniates through anelus fibrosus
• posterolaterally (due to the strengh of anterior longitudinal ligament)
• compression of spinal nerve roots → pain along the nerve (one number below nerve)
• most commom:
  
  • lower lumbar (L4/L5 and L5/S1 - sciatica)
  • lower cervical (C5/C6 and C6/C7)

Question 7

SPINAL MENINGES

Dura Mater

Answer 7

• tough + cylindrical
• dural sac
• termination: S2 (vertebral level)
• epidural space → internal vertebral venous plexus
  
  • valveless
  • connection with pelvic, thoracic and abdominal veins + dural venous sinuses (foramen magnum)
  • route of metastasis

Question 8

SPINAL MENINGES

Arachnoid

Answer 8

• delicate membrane
• termination: S2
• subarachnoid → cerebrospinal fluid

Question 9

SPINAL MENINGES

Pia Mater

Answer 9

• tightly attached to spinal cord
• termination: L1/L2 (vertebral level) - conus medullaris
• specializations
  
  • denticulate ligament - separation of ventral/dorsal roots + anchor dura mater
  • filum terminale - part of cauda equina (with ventral and dorsal roots of lumbar and sacral spinal nerves)

Question 10

SPINAL MENINGES

Clinical Correlate: Lumbar Puncture

Answer 10

• epidural anesthesia
• withdrawn CSF in subarachnoid space
• L4/L5 interspace → horizontal line top of iliac crest (L4 vertebrae)
• needle pass through interlaminar space: skin → fascia → supraspinous ligament → intraspinous ligament → interlaminar space (ligamenta flava) → epidural space → dura → arachnoid → subarachnoid space

Question 11

SPINAL NERVES

Generalities

Answer 11

• 31 pairs
  
  • 8 cervical
  • 12 thoracic
  • 5 lumbar
  • 5 sacral
  • 1 coccygeal
• C1-C7 → exit the intervertebral foramena superior
• C8 → transition point, exits the intervertebral foramen inferior to the C7 pedicle
• T1 and below → exit the intervertebral foramena inferior

Question 12

MUSCLES

Back Muscles

Answer 12