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Anatomy of the Vertebrae and Spinal Cord

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Part 1: The Vertebral Column

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Part 2: Structure of a Typical Vertebra

Key Structural Components

• Anterior, ovoid-shaped, weight-bearing part
• Linked to adjacent bodies by intervertebral discs and ligaments
• Size increases from C to L as weight load increases

• Two pedicles - bony pillars attaching arch to body; their superior/inferior notches form the intervertebral foramina
• Two laminae - flat sheets extending from each pedicle meeting in the midline; form the "roof" of the arch

• Spinous process - projects posteriorly/inferiorly from the junction of laminae; muscle and ligament attachment
• Transverse processes (2) - project posterolaterally from the pedicle-lamina junction; muscle/ligament attachment; articulate with ribs in the thoracic region
• Articular processes (4 total: 2 superior, 2 inferior) - form the facet (zygapophyseal) joints with adjacent vertebrae

• Space enclosed by the vertebral body anteriorly and arch posterolaterally
• All foramina together form the vertebral (spinal) canal, which houses and protects the spinal cord

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Part 3: Intervertebral Discs

• Nucleus pulposus - central gelatinous core; shock absorption
• Annulus fibrosus - peripheral ring of fibrocartilage lamellae; resists torsion and compression
• Hyaline cartilage endplates - interface between disc and vertebral body

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Part 4: Regional Differences

Cervical Vertebrae (C1-C7)

• Smallest vertebral bodies; square-shaped from above
• Foramen transversarium in each transverse process (transmits vertebral artery)
• Spinous processes are short and bifid (C2-C6)
• Triangular vertebral foramen
• C1 (Atlas) - no vertebral body; ring-shaped; supports the skull; atlas-occipital joints allow nodding ("yes")
• C2 (Axis) - has the dens (odontoid process) projecting superiorly from its body (the fused body of C1); pivot for rotation ("no") at the atlanto-axial joint

Thoracic Vertebrae (T1-T12)

• Heart-shaped bodies; larger than cervical
• Costal facets on vertebral bodies (superior and inferior) and on transverse processes for rib articulation
• Long spinous processes pointing sharply inferiorly
• Circular vertebral foramen

Lumbar Vertebrae (L1-L5)

• Largest, kidney-shaped bodies
• Massive rectangular spinous processes
• Large triangular vertebral foramen
• Costal processes (homologous to rudimentary ribs) instead of true transverse processes
• Greatest range of flexion/extension

Sacrum & Coccyx

• 5 sacral vertebrae fused in adults; articulates with L5 above and coccyx below
• Sacral foramina for anterior and posterior sacral nerve rami
• Coccyx is vestigial and has no clinical relevance

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Part 5: Anatomy of the Spinal Cord

General Features

• In adults, it terminates as the conus medullaris at L1-L2
• In neonates, it ends at approximately L3
• Below the conus, nerve roots form the cauda equina ("horse's tail")
• A fibrous strand called the filum terminale extends from the conus to the coccyx

• Cervical enlargement (C5-T1) - gives rise to brachial plexus for the arms
• Lumbosacral enlargement (L1-S2) - gives rise to lumbar/sacral plexus for the legs

Meninges and Spaces

1. Pia mater - innermost, adherent to cord surface
2. Arachnoid mater - middle layer
3. Dura mater - outermost, tough fibrous layer

• Subarachnoid space (between pia and arachnoid) - contains cerebrospinal fluid (CSF)
• Epidural space (between dura and vertebral canal periosteum) - contains fat and venous plexuses; clinically important for epidural anesthesia

Segments

• 8 cervical, 12 thoracic, 5 lumbar, 5 sacral, 1 coccygeal

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Part 6: Internal Structure of the Spinal Cord

Gray Matter (Central - "Butterfly" or "H" Shape)

White Matter (Surrounding Gray Matter - 3 Columns/Funiculi)

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Part 7: Spinal Nerve Roots

• Dorsal (posterior) root - sensory; contains the dorsal root ganglion (DRG) just outside the cord, which houses sensory neuron cell bodies
• Ventral (anterior) root - primarily motor; lower motor neuron axons

1. Posterior (dorsal) ramus - back muscles and skin
2. Anterior (ventral) ramus - limbs and anterior trunk

Nerve Root Exit Levels (Clinically Important)

• C1-C7: exit above the pedicle of the same number (C6 root exits between C5-C6)
• C8: exits between C7 and T1 (there is no C8 vertebra)
• T1 and below: exit below the pedicle of the same number (L4 root exits between L4-L5)

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Summary Table

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Vertebrae (ریڑھ کی ہڈی) aur Spinal Cord ki Anatomy

Roman Urdu mein

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Hissa 1: Vertebral Column (Ridh ki Haddi ka Silsila)

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Hissa 2: Ek Aam Vertebra ki Banawat

Mushkil Alfaaz ki Definitions:

• Vertebral Body (Vertebral Body) = Haddi ka agla, mota, gol hissa jo bojh uthata hai. Sochein ek drum ki tarah.
• Vertebral Arch (Vertebral Arch) = Pichli taraf ka mehra/darwaza — yeh spinal cord ko dhakta hai.
• Pedicle (Pedicle) = Chhoti sii tang/stalk jo body ko arch se jodti hai. Do hoti hain — daien aur baien.
• Lamina (Lamina) =납ti plate jo dono pedicles ko peeche milati hai aur arch ki "chhat" banati hai.
• Spinous Process (Kanta) = Pichhe ki taraf nikla hua kanta — yahi aap peeth par tangent feel karte hain. Muscles aur ligaments yahan chipakti hain.
• Transverse Process (Side Wala Kanta) = Dono taraf laterally niklta hai — muscles ka attachment point.
• Articular Process (Jor wala hissa) = Upar-neeche ki vertebrae se milne ka hissa — Facet Joint banata hai.
• Vertebral Foramen (Surakh) = Arch aur body ke beech ka khulli jagah jahan spinal cord guzarti hai.
• Vertebral Canal (Nali) = Tamam vertebral foramina mil kar ek nali banati hain — spinal cord is nali mein mehfooz hoti hai.

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Hissa 3: Intervertebral Disc (Do Haddiyon ke Darmiyan Takiya)

• Nucleus Pulposus = Disc ka beech wala geeli mitti/jelly jaisa part. Pressure absorb karta hai.
• Annulus Fibrosus = Bahari sakht ring jo nucleus ko ghyerti hai. Fiber ki tahen hoti hain. Jab yeh phate to slip disc hoti hai.
• Hyaline Cartilage Endplate = Disc aur haddi ke beech ki chikni teh.

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Hissa 4: Alag Alag Ilaqon ki Vertebrae

Cervical (Gardan) — C1 se C7

• Sab se chhoti haddiyan
• Foramen Transversarium = Transverse process mein ek chota surakh jis se Vertebral Artery (gardan ki khoon ki nali) guzarti hai
• Spinous process bifid (kanta do hisson mein banta hai) hota hai C2 se C6 tak
• Atlas (C1) = Sab se upar wali haddi, iska koi body nahi hota — sirf ring hai. Sar ko agay pichay hila ne deta hai ("haan" wali harkat)
• Axis (C2) = Iske upar ek keel jaisi haddi niklti hai jise Dens/Odontoid Process kehte hain. Sar ko ghumane deta hai ("naa" wali harkat)

Thoracic (Seena) — T1 se T12

• Costal Facets = Pasliyon se jorne ke liye chote jod (facets) hote hain
• Spinous processes lambe aur neeche ki taraf jhuke hote hain

Lumbar (Kamar) — L1 se L5

• Sab se bari aur moti vertebrae
• Sab se zyada movement (jhukna, seedha khara hona)
• Koi pasli wala hissa nahi

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Hissa 5: Spinal Cord (Ridh ki Nali ke Andar ki Naas)

Aam Jaankari

• Spinal cord dimaag se shuru hoti hai aur L1-L2 tak khatam hoti hai (adults mein)
• Wahan ek makhrooti nok banati hai jise Conus Medullaris kehte hain
• Uske baad nerve roots ka guchha hota hai jise Cauda Equina ("ghore ki dum") kehte hain
• Ek patli dhaga Filum Terminale conus se coccyx tak jata hai

Spinal Cord ke 2 Motape (Enlargements)

• Cervical Enlargement (C5-T1) = Baazuon ke liye nerves yahan se nikalti hain (Brachial Plexus)
• Lumbosacral Enlargement (L1-S2) = Taangon ke liye nerves yahan se nikalti hain (Lumbar/Sacral Plexus)

Meninges (Jhalliyan — Spinal Cord ki Hifazat)

• Subarachnoid Space = Pia aur Arachnoid ke darmiyan jagah — CSF (Cerebrospinal Fluid) yahan hota hai
• CSF = Dimaag aur spinal cord ke aas paas bahnay wala saaf paani jaisa maaya — hifazat karta hai aur ghiza pohanchata hai
• Epidural Space = Dura ke bahar ki jagah — epidural injection yahin di jati hai (dard kam karne ke liye)

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Hissa 6: Spinal Cord ka Andar ka Dhanca

Gray Matter (Bhoori Mitti wala Hissa — Butterfly Shakal)

• Rexed's Laminae = Gray matter ko aur bhi chote hisson (I se X) mein taqseem kiya gaya hai — har lamina ka alag kaam hai

White Matter (Safed Hissa — 3 Columns)

Mushkil Alfaaz ki Definitions:

• Tract = Naason ka rasta ya raah — jaise motorway par ek lane
• Ascending Tract (Upar wala rasta) = Mehsoosat (sensory signals) jism se dimaag ki taraf jati hain
• Descending Tract (Neeche wala rasta) = Hukum (motor signals) dimaag se jism ki taraf aata hai
• Dorsal Column = Pichhe wala column — fine touch, vibration, proprioception carry karta hai
• Spinothalamic Tract = Dard aur temperature ki information carry karta hai — pehle ulti taraf jaata hai phir upar
• Corticospinal Tract = Dimaag se voluntary muscle movement ka hukum laata hai
• Proprioception = Apne jism ki position aur harkat ka andazi ilm — aankhein band ho tab bhi pata hota hai haath kidhar hai
• Somatotopic Organization = Cord ke andar har body part ki apni jagah hoti hai — cervical (gardan wali) naasein center mein, sacral (neeche wali) bahar ki taraf — isliye central cord injury mein zyada haath mutaasir hote hain taangon se

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Hissa 7: Nerve Roots (Naason ki Jarein)

• Dorsal Root (Sensory Root) = Mahsoosat ki jad — jism se cord mein daakhil hoti hai. Iska ek Dorsal Root Ganglion (DRG) hota hai jahan sensory neurons ke cell bodies hote hain. Ganglion = Naason ke cell bodies ka guchha
• Ventral Root (Motor Root) = Harkat ki jad — cord se nikal kar muscles ko signal deti hai

• Posterior Ramus = Peeth ki muscles aur skin
• Anterior Ramus = Haath, paon aur aage ka hissa

Klinical Niqta — Nerve kahan se nikalti hai?

• C1-C7: Apni vertebra ke UPAR se nikalti hai (C6 root C5-C6 ke darmiyan se)
• C8: C7 aur T1 ke darmiyan (C8 vertebra hoti hi nahi!)
• T1 se neeche sab: Apni vertebra ke NEECHE se nikalti hain (L4 root L4-L5 ke darmiyan)

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Mukhtasar Matlab — Mushkil Alfaaz Ek Jagah

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