Spinal cord D.Nimer D.Rania Gabr D.Safaa D.Elsherbiny

Objectives Describe the gross anatomical features of the spinal cord. Describe the level of the different spinal segments comparing to the level of their respective vertebrae. Identify important gross features of spinal cord, nerve roots, and spinal ganglia. Describe the internal features of spinal cord (gray matter and white matter) in the different regions.

External features o Length: 45cm in adult male & 42cm in adult female. o Location: upper 2/3 of vertebral column. o Begins: continuation of at level of C1. o Ends: its lower end called conus medullaries.  in newborn: al the level of L3.  In the adult: at the lower border of L1.

External features

o Fissures and sulci:  Anterior & posterior median fissure.  Anterolateral fissure: marks the attachment of ventral root.  Posterolateral fissure: marks the attachment of dosral root.  Posterior intermediate fissure: separate gracil from cuneate tracts.

Spinal Enlargements Enlargements: two 1.Cervical enlargement : (C5-T1) in the cervical region & gives origin to brachial plexus. 2.Lumbar enlargement : (L1-S2) in the lumbar region & gives origin to lumbosacral plexus.

Spinal meninges o Dura matter: outer, ends at level of S2 vertebra. o Arachnoid matter: middle, ends at level of S2 vertebra. o Pia matter: inner and forms 2 ligaments  Filum terminale: from conus medullaris to back of coccyx. Divided by lumbar cistern into filum terminale interna and externa.  2 denticulate ligaments: Extend from pia to dura. It s lateral edge have 21 process.

Dura arachnoid S.C

lumbar cistern o It is lower part of subarachnoid space. o Extends from L2-S2. o Contents:  CSF.  Cauda equina (roots of lumbar and sacral nerves).  Filum terminlae interna.

Spinal cord segments o 31 segments:  8 cervical.  12thorcic.  5 lumbar.  5 sacral.  1 coccyxgeal.

Relation of spinal nerves to vertebrae. Each cervical nerve emerge above its corresponding vertebra.  C1 above atlas.  C4 above C4 vertebra.  C8 above T1.  All other spinal nerves from T1 downward emerge below corresponding vertebrae.

Relation of spinal nerves to vertebrae.

Internal structure of S.c. S.C. divide into 2 halves by anterior and posterior median fissure. Each half formed of inner grey matter and outer white matter. 2 halves connected together by:  white commissure.  Anterior grey commissure.  Posterior grey commissure.

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The white matter is formed primarily of the axons of the nerve cells called tracts. It is organized into three funiculi: dorsal, lateral and ventral. The name of the tract denotes its origin and termination such as: Spinocerebellar tract: from the spinal cord to the cerebellum. Corticospinal tract: from the cerebral cortex to the spinal cord. SPINAL CORD WHITE MATTER

SPINAL CORD GRAY MATTER The gray matter is H-shaped contains the nerve cell bodies. It is formed of 3 horns on each side: 1.Ventral horns (motor): contains motor neurons 2.Dorsal horns (sensory): contains four nuclear groups: a)Posteromarginal nucleus: mediates pain and temperature sensations. b)Substantia gelatinosa of Rolandi: It is associated with pain & temperature sensation. c)Nucleus proprius: It mediates pain, temperature, touch and pressure sensations. d)Nucleus dorsalis (Clarke s nucleus): extends from C8 to L2 segments. It is associated with unconscious proprioception. 3.Lateral horns (sympathetic): present only in the thoracic & upper lumbar segments (T1 to L2 or L3 segment. It contains the preganglionic sympathetic nerve cells.