1st lecture Spinal cord.pdf

Anatomy of the Spinal cord By: Dr. Mariam Atef Lecturer of Anatomy  Nervous System Central nervous system Autonomic nervous system Peripheral nervous system Brain Spinal cord  The Neuron Is the Functional and the Str...

Anatomy of the Spinal cord By: Dr. Mariam Atef Lecturer of Anatomy  Nervous System Central nervous system Autonomic nervous system Peripheral nervous system Brain Spinal cord  The Neuron Is the Functional and the Structural unit of the nervous system  Spinal cord Site and Length: It occupies the upper 2/3 of the vertebral column It is about 45 cm in length in males and 42 cm in females  Extent of the spinal cord It begins as a continuation of the medulla oblongata at the lower border of the foramen magnum of the skull. Below: the lower end of the cord tapers forming Conus medullaris By the 3rd month of IU life , it occupies the whole length of vertebral column At birth: it ends at the level of L3 vertebra In adults: it ends at the level of the disc between L1/L2 vertebrae Foramen Magnum of the skull Shape: Cylindrical and shows 2 enlargments Cervical enlargement: C5-T1 segments Lumbar enlargement: L1-S3 segments Spinal cord extent  Horizontal section of the spinal cord H- shaped gray matter surrounded by the white matter  External features of the Spinal cord Its external surface shows 6 longitudinal grooves or sulci: 1- Anterior median fissure: deepest 2- Posterior median sulcus. 3- Two anterolateral sulci: for exit of the ventral (motor) root 4- Two posterolateral sulci: for entry of the dorsal (sensory) root Spinal nerves What is Cauda Equina? A leash of the long lumbar and sacral nerve roots, surrounding the filum terminal together forming the cauda equine which float in the CSF filling the subarachnoid space. Length of the roots and the cauda equina: Since the spinal cord is shorter than the vertebral column: - Therefore, the roots of the spinal nerves have to descend for some distances in the subarachnoid space to reach their intervertebral foramina. Accordingly, the roots of the spinal nerves become progressively longer and more oblique as we go downwards. - Below the end of the spinal cord (below L1 vertebra), the vertebral canal is occupied only by a leash of the long lumbar and sacral nerve roots, surrounding the filum terminal together forming the cauda equine which float in the CSF filling the subarachnoid space. Lumbar puncture can be safely done below L2 vertebra without any danger of injury of the spinal cord. Spinal meninges Spinal cord meninges Spinal pia mater  Arachnoid mater Very important space Dura mater Fixation of spinal cord in position Blood supply of Spinal cord Blood supply of the Spinal cord 3- Radicular spinal arteries: They arise from the Vertebral arteries, Posterior intercostal arteries, Lumbar arteries and Lateral sacral arteries on either side. They enter the vertebral canal through the intervertebral foramina and divide into anterior and posterior branches which run along the ventral and dorsal spinal nerve roots. They are the main source of blood supply to the lower 1/3 of the Spinal cord. One of the radicular arteries is very large and supplies the lumbar enlargement called Arteria radicularis magna  Venous drainage They are 6 longitudinal venous channels: Anteromedian and posteromedian channels Rt and Lt anterolateral channels Rt and Lt posterolateral channels These channels are drained by radicular veins which drain into the internal vertebral venous plexus present in the epidural space.  MCQ’s 1- 2-  MCQ’s 3- Thank you