Spinal Cord I Dr Ayman Abu-Tabanja

33 Vertebrae (segments): Vertebral Column 33 Vertebrae (segments): 7 Cervical 12 Thoracic 5 Lumbar 5 Sacral 4 Coccygeal

Spinal (vertebral) canal Intervertebral foramen

COVERINGS OF THE SC Dura mater Tube-like Continuous with cranial dura Extend to S2 Innervation

COVERINGS OF THE SC Arachnoid mater Oppose the inner side of dura Outer boundary of subarachnoid space Termination Lumbar cistern

COVERINGS OF THE SC Pia mater Delicate Tightly adherent to spinal cord Vascular

Epidural space: Filled with fat Venous plexus Spinal nerve roots cuadal to S2

Subarachnoid space: CSF-filled Denticulate ligament: Pia-arachnoid tissue Serrated Appearance Suspend spinal cord in middle of spinal canal

Spinal cord consist of 31 segments Vertebral column grows faster than spinal cord

SPINAL VERSUS VERTEBRAL SEGMENTS C1 nerve (suboccipital nerve) C2-C7 nerve C8 nerve ALL T & L nerves All S nerves Co nerve

Gross morphology Cylindrical Flattened dorsoventrally Has two enlargements 1. Cervical enlargement: C4-T1 2. Lumbar enlargement: L2-S3

Anterior median fissure Posterior median sulcus Motor rootlets Sensory rootlets

Conus medullaris Cauda equina Filum terminale: Internum & externum Adhere to dorsum of coccyx

Lumbar Puncture

Lateral Recumbent Position

Structure of Spinal Cord

The Gray mater H- shaped Anterior & posterior gray horns Gray commissure Lateral gray horns

Anterior Gray Columns Contain: Alpha motor neurons Larger multipolar 2. Gamma motor neurons Smaller multipolar Neurons arranged in three groups: Medial group Central group Lateral group

Anterior Gray Columns Medial group Present in all segments Supply neck, trunck, intercostal and abdominal muscles 2. Lateral group Present in enlargements Supply upper and lower limbs

Anterior Gray Columns 2. Central group: smallest Phrenic nucleus: C3-5 Accessory nucleus: C1-C5/6 C. Onuf’s nucleus: Sacral segments

Posterior gray columns Three main nerve cell groups: Substantia gelatinosa group: Most posterior All segments Somatic sensations Glogi II neurons

Posterior gray columns 2. Nucleus proprius: Largest group All segments Large neurons proprioception, two point descrimination, and vibration

Posterior gray columns 3. Nucleus dorsalis (clarke’s group): Most anterior Large neurons present from C8-L4 Associated with Proprioceptive endings (muscle and tendon spindles)

Posterior gray columns 4. Visceral afferent nucleus Lateral to nucleus dorsalis Medium neurons present from T1-L3 Receives visceral sensations

Lateral Gray Horn Present in T1 to L3 Contain intermediolateral cell group Give rise to preganglionic sympatheic fibers ***There is intermediolateral group in S2-S4

The gray commissure Connects anterior and posterior horns on each side The central canal is located in it’s center Divided into: Anterior gray commissure Posterior gray commissure The central canal present throughout the spinal cord Lined with ependyma Filled with CSF Closed inferiorly ( terminal ventricle)

White matter Divided into: Anterior funiculi 2. Lateral funiculi Posterior funiculi Gracile fasciculus Cuneate fasciculus

White matter