Spinal Cord Flashcards
blood supply of spinal cord where located?
-2 posterior spinal arteries (right and left)
-1 anterior spinal artery
-Located in the subarachnoid
space
Anatomical divisions of nervous system
-Central nervous system (CNS): Brain and spinal cord
-Peripheral nervous system (PNS): Nerves distributed throughout the body
• 12 cranial nerves
• 31 spinal nerves
Functional divisions: afferent vs efferent
• Afferent (Sensory)
- Somatic: body wall structures
-Visceral: organs, blood vessels
• Efferent (Motor)
- Somatic: voluntary muscle movements
Autonomic
• Sympathetic- fight or flight
• Parasympathetic- rest or digest
Spinal cord development
- Up to 8th week of development the spinal cord and vertebral column are the same length
- Spinal nerves run directly into corresponding musculoskeletal blocks (somites)
- After 3rd month vertebral column elongates
- Spinal nerves must course inferiorly
-Cell bodies for spinal nerves are at a higher vertebral level than the structures
they innervate.
-More pronounced inferiorly
Spinal cord: Extent and Regionalization?
Superior border - Foramen magnum
Inferior border – L1/L2 (spinal nerves continue)
Regionalization
• Cervical (C1-C8) • Thoracic (T1-T12) • Lumbar (L1-L5) • Sacral (S1-S5) • Coccygeal (Co1)
Spinal cord: Length and weight
Length • In males it measures 45cm • In females it measures 43 cm
Weight • Spinal cord weighs approximately 35 grams
Shape: The spinal cord is an
elongated cylindrical
structure.
The shape is obscured by a cervical
enlargement and lumber enlargement.
At the termination it is dilated forming the
conus medullaris the conus
spinal cord enlargements?
- Cervical (C5-T1)
Source of brachial plexus, upper limb innervation
- Lumbosacral (L1-S3)
Lumbar/Sacral plexus
Lower limb innervation
Spinal cord: Inferior end
-Spinal cord cell bodies end inferiorly at the conus
medullaris.
-Spinal nerves continue inferiorly forming a
structure called the cauda equina.
-The pia mater extends to form a thin filament, the
filum terminale.
Spinal cord: Surface features
Anterior median fissure: Contains anterior vessels
Posterior median sulcus
Anterolateral sulcus: ventral rootlets emerge
Posterolateral sulcus: dorsal rootless emerge
Posterior intermediate sulcus: Present in cervical/upper thoracic levels
-Divides gracile and cuneate fibers of the posterior trac
spinal cord cross section
- central canal
- white matter: myelinated axons
- grey matter: contains neuron cell bodies
Grey matter: what does posterior (dorsal) horn consist of?
• Afferent/Sensory
afferent/sensory fibers
what does the anterior or ventral horn consist of?
somatic efferent/motor fibers
what does the lateral column of grey matter consist of and give the anatomy/function?
Autonomic Efferent fibers
- T1-L2 – Intermediolateral column (sympathetics), constitutes the thoracolumbar outflow
-S2-4 – Parasympathetics
• Give rise to pelvic splanchnic nerves.
Posterior horn: Cross-sectional anatomy, explain the marginal zone (MZ, posterior
marginalis)?
• located at the tip of the dorsal
horn ((Laminae I)
• Important for relaying pain and
temperature sensation to the
brain.
Posterior horn: Cross-sectional anatomy, explain Substantia gelatinosa of Rolando
- Present at the tip of the posterior horn
- It extends the entire length of spinal cord.
explain the dorsolateral tract of Lissauer
- White mater dorsal to the substantia gelatinosa
- It extends the entire length of spinal cord
explain nucleus proprius
- Ventral/anterior to substantia gelatinosa
- It extends the entire length of spinal cord
- it occupies the head and neck of the posterior horn
Posterior horn: Cross-sectional anatomy, nucleus thoracis or the dorsal nucleus of clarke
- Ventral to the nucleus proprius
- Present in T1 - L3/L4 cord segment
- It occupies the base of the posterior horn (Laminae VII)
‘• Composed mostly of large neurons
• Concerned with information from muscle spindles and tendon organs (relays unconscious
proprioceptive information to the brain)
Visceral Afferent Nucleus
- Anterolateral to the dorsal nucleus of clarke ((Lamina VII)
- Contains autonomic neurons similar to lateral horn.
- Afferents: Visceral afferents
- Composed mostly of medium size neurons
- Extends from T1 to L3 segments
White mater of spinal cord: Cross-sectional anatomy
• The white mater of the spinal cord subdivides into columns termed ________ and designated as ________
Funiculi is designated as:
- Anterior funiculus
- Lateral funiculus
- Dorsal funiculus
Anterior funiculus location
- lies in between the anterior median fissure and ventral nerve
root.
- Across the midline the anterior funiculi of both sides interconnect by way of
ventral white commissure
White mater of spinal cord: Cross-sectional anatomy • The white matter of
spinal cord contain? which vessels? What are the nerve fibers called?
-blood vessels & bundles
of nerve fibres.
- These bundles of nerve
fibres are called
tracts/fasciculi.
-A tract has a common function and fasciculi has diverse functions.
Anterior funiculus contains two tracts the ________ and the ________
ascending tract and descending tract
the ascending tract of the anterior funiculus is the _____
anterior spinothalamic tract
the descending tract of anterior funiculus contains:
Anterior corticospinal tract: lying most medial to the anterior median fissure
• Tectospinal tract
• Vestibulospinal tract
• Olivospinal tract
the lateral funiculus ascending tract contains:
- Lateral spinothalamic tract
- Anterior spinocerebellar tract
- Posterior spinocerebellar tract
Posterior funiculus:
A posterior intermediate septum subdivides the posterior funiculus into
medial and lateral part
• Contains dorsal column–medial lemniscus
pathway (DCML)
• Conveys fine touch, vibration, two-point
discrimination, and proprioception (position) from the skin and joints.
Dura mater:
- Tough outer covering
- It is mesodermal in origin
- Attaches to the coccyx, CC1 via filum terminale
• A subdural space separates dura mater
from arachnoid mater
arachnoid mater:
-Web-like
- Ends at S2 vertebra
- Attached to dura though denticulate ligments
-contains CSF (subarchnoid space)
pia mater:
- Thin layer on surface on spinal cord
- Adherent to the surface of the spinal cord by pia-glia membrane
- Attached to dura by denticulate ligaments
the pia and arachnoid mater are called _____ and are derived from ________
Leptomeninges derived from neural crest cells
Other Arteries of spinal cord other are the_____ and originate from the ______ branches of _____
- anterior segmental medullary arteries
- posterior segmental medullary arteries
originate from cervical vertebral artery at level of branches C3-C8
The largest anterior segmental medullary
artery is the ________
The largest anterior segmental medullary
artery is the artery of Adamkiewicz arteria (radicularis magna)
venous blood supply of spinal cord in archanoid space:
- Anterior spinal vein
- Posterior spinal vein
venous blood supply in epidural space:
venous plexus (internal vertebral plexus)
the epidural space contains ______ and ______ (blood supply)
extradural fat and internal vertebral venous plexus
the epidural space is only located around ______ and not found in the _______
spinal cord, no epidural space in skull
spinal nerves regionalization and numbering
- 8 cervical
- 12 thoracic
- 5 lumbar
- 5 sacral
- 1 coccygeal
• Number matches superior vertebral body
• EXCEPT – Cervicals
Nomenclature of Spinal Nerves
note change in relation between spinal nerve number and vertebral number in cervical region
- C1 exits superior to atlas.
- C7 exits superior to C7 vertebra.
- C8 exits between C7 and T1 exits inferior to T1 vertebrae.
Cervical spinal nerves are _____ and ____ oriented
short and horizontally
the cauda equina in dural sac. The dural sac extends from _____ to approximately ______ along with the ______mater and creates a large cistern of ______.
• Dural sac extends from foramen magnum to ~ S2, along
with arachnoid; creates a large cistern of CSF.
pia mater from _________ extends within the dural sac, then externally to attach to the ______ known as the ______
pia mater from conus medullaris extends to externally attach to the filum terminale
Spinal nerves in the cauda equina exit _____ to
vertebra of the _____ number
inferior, to same number of vertebrae
lumbar cord lies within:
sacral cord lies within:
lumbar cord lies within: T11 and T12
sacral cord lies within: L1 and L2 vertebrae