Spinal Cord

Definition:
Elongated and cylindrical part of the central nervous system which is contained in the upper two-third of the vertebral canal.

Function:
Integration and association of sensory modalities.


Extent :
Begin as continuation of the medulla oblongata at the level of the upper border of posterior arch of Atlas above (rostral) to first pair of cervical nerve , cuts middle of dens Axis vertebrae and end as a pointed end -conus medularis at the level of L1.


Dimension :
Length - 45cm in male and 42 cm in female
Weight- 30 gm

Enlargements :
Cervical C4-T2
Lumbosacral L1-S3

SEGMENT
Part of the spinal cord where a pair of spinal nerves is attached.

Coverings:
Duramater (endosteal + meningeal)
Acachnoid mater
Piamater

Contents of epidural space
fat
connective tissue
internal vertebral venous plexus


Filum terminale:
Continuation of piamater .
starts from the lower end of spinal cord at level of L1.
Has 2 parts : Filum terminale internum-15cm and filum terminale externum-5cm

Best site for lumbar puncture :
Adult : between L3-L4
Infant: between L4-L5

Protection of spinal cord
Vertebral canal
Meninges
Hydrostatic pressure of CSF
Filum terminale
Ligamentum denticulatum


Arterial supply of spinal cord.
2 sources
1. Longitudinally oriented vessels
anterior spinal artery
posterior spinal artery

2. segmental spinal arteries derived from:
verterbral artery
deep cervical arteries
posterior intercostal arteries
lumbar arteries


Structure of spinal cord :
Inner core of the Grey matter and outer white matter


Nerve cell groups in :
Anterior grey column
alpha efferent
and
gamma efferent

Posterior grey column
substantia Gelatinosa
Nucleus proprius
Nucleus dorsalis
Visceral affarent nucleus