Spinal Cord
Description
General
- Tubular bundle of nervous tissue extending from the brainstem to the lumbar vertebrae
- When combined with the brain, forms the central nervous system
Gross Anatomy
- Cylindrical structure, grey-white in color
- Arises as a continuation of the medulla (inferior part of the brain stem))
- Travels inferiorly within the vertebral canal
- Protected/ surrounded by meninges which contain cerebrospinal fluid
- At approximately L2, the cord tapers off forming conus medullaris
- The spinal nerves bundled together at the end of the conus are known as cauda equina
- Cervical enlargement: located at C4-T1, represents origin of brachial plexus
- Lumbar enlargement: located at T11-L1, represents origin of lumbosacral plexus
Spinal Meninges
- Three membranes that surround the spinal cord
- Function: contain cerebrospinal fluid, support and protect the spinal cord
- Dura mater: most external of the meninges
- Arachnoid mater: middle layer
- Pia Mater: innermost layer
Formation of Spinal Nerves
- Mixed nerves that originate from the spinal cord, forming the peripheral nervous system
- Each nerve begins as a anterior/motor and posterior/sensory nerve root
- They coalesce at the intervertebral foramina forming a single spinal nerve unit
- When they exit the intervertebral foramina, they divide into two rami
- Posterior rami: nerve fibers to the synovial joints of the vertebral column, deep muscles of the back, and the overlying skin
- Anterior rami: nerve fibers to much of the remaining area of the body, both motor and sensory
Vasculature
- Anterior spinal artery formed by branches of the vertebral arteries
- Posterior spinal arteries originate from the posteroinferior cerebellar and vertebral arteries
- Artery of Adamkiewicz supplies inferior 2/3 of the spinal cord
- Venous drainage is through three anterior/posterior spinal veins
See Also
References
- ↑ II, Phillip A. Swanson, and Dorian B. McGavern. "Portals of viral entry into the central nervous system." The blood-brain barrier in health and disease, Volume two: Pathophysiology and pathology 23 (2015).
- ↑ Kraan, Gerardus Arnoldus. "The extraforaminal ligaments of the human spinal nerves. Anatomical and Biomechanical study." (2012).
- ↑ Facchin, Marco, Marco Viola, and Elia Zanin. "Retiring the “Cinderella view”: the spinal cord as an intrabodily cognitive extension." Biology & Philosophy 36.5 (2021): 45.