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Anatomy of spinal cord
1. ANATOMY OF SPINAL CORD
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REFERENCES: Snells anatomy; Dejongâs neurologic examination, Hendelman atlas of functional neuroanatomy; Waxnan clinical neuroanatomy
Dr YELDHO EASON
Transverse section of spinal cord
The adult spinal cord is normally 42 to 45 cm long in
adults and is continuous with the medulla at its upper end.
The conus medullaris is the conical distal (inferior) end of
the spinal cord. In adults, the conus ends at the L1 or L2
level of the vertebral column.
The spinal cord is divided into approximately 31 segments
â8 cervical (C) segments, 12 thoracic (T) segments, 5
lumbar (L) segments, 5 sacral (S) segments, and a few
small coccygeal (Co) segmentsâthat correspond to
attachments of groups of nerve roots
LAMINATIONS OF THE SPINAL CORD
2. ANATOMY OF SPINAL CORD
REFERENCES: Snells anatomy; Dejongâs neurologic examination, Hendelman atlas of functional neuroanatomy; Waxnan clinical neuroanatomy
Dr YELDHO EASON
VENOUS DRAINAGE OF SPINAL CORD.
Venous drainage is by
- six irregular plexiform channels
- There is one each along the, anterior and posterior
midlines and along the line of attachment of dorsal
and ventral roots.
- These are drained by radicular veins into epidural
venous plexus
- Batsonâs plexus (valveless spinovertebral venous
plexus) continues upwards into the intracranial cavity,
which may be a means of transport of tumor cells.
ARTERIAL SUPPLY OF SPINAL CORD.
Arterial supply is via
1) One anterior spinal artery
â a branch of vertebral artery
â descends the entire length of spinal cord at the
anterior median fissure
â supplies anterior 2/3rd
of spinal cord
2) Unpaired anterior medullary arteries
- branch of lateral spinal artery, which in turn
is a branch of intercostal artery
- divides into anterior and posterior radicular
branches to anastamose with anterior
spinal and posterior spinal arteries
respectively
- supply the peripheral areas of the cord
3) A pair of posterior spinal arteries
- branches of vertebral arteries
- supply posterior horns and dorsal funiculi
4) Central arteries
- branch of anterior spinal artery
- supply central portions of the cord on both
sides
5) Artery of Adamkiewicz
- largest medullary artery
- arises between T9 to L2 levels
- reinforces the supply to lumbar segments
Special points::
1. Anastomosis is least efficient at the region of lateral
columns
2. Cervical and lumbar segments have rich vascular supply
3. T1 to T4 segments are most vulnerable to ischemia
4. Anterior spinal artery thrombosis causes ischemia of
anterior 2/3rd
of the cord, sparing the posterior column,
hence leads to dissociated sensory loss.