Mod5-Obj1: The spinal cord Flashcards
The spinal cord
Structurally and functionally integrated with the brain
The spinal cord is composed of
Interneurons
The spinal cord receives and directs…
Incoming sensory information to processing centres in the brain
The spinal cord receives and relays…
Motor output from the brain
The spinal cord initiates…
Spinal reflexes
The vertebral column
The spinal cord is encased within the vertebral canal, formed by alignment of multiple vertebral foramen
Spinal cord runs through here
Vertebral foramen
Spinal nerves exit here
Intervertebral foramen
Gross anatomy of the spinal cord
Approximately 42cm long and 14mm wide
-Extends from foramen magnum to L2 in adults and L4 in infants
The spinal cord terminates in a cone shaped structure called the
Conus medullaris
Filum terminale
Fibrous connective tissue extending from the conus medullar is to anchor the spinal cord to the coccyx
Divided into 31 segments
1.) Cervical (C1-C8)
2.) Thoracic (T2-T12)
3.) Lumbar (L1-L5)
Conus medullaris
4.) Sacral (S1-S5)
5.) Coccygeal (CO1)
Lumbar, sacral and coccygeal segments of the spinal cord are
“squeezed” into the conus medullaris
Spinal nerves
Short nerves
- Contain both sensory & motor axons
- Connect to the spinal cord at one end and branch to form peripheral nerves at the other
Spinal nerves attach to the spinal cord by paired nerve roots
Ventral and dorsal roots
Ventral root
Contains the axons of motor neurons (issues motor commands to effector glands and muscles)
Dorsal root
Contains the axons of sensory neurons (relays input from receptors to the spinal cord)
-Cell bodies of these sensory neurone lie within the dorsal root ganglion
Example of dorsal root (way into spinal cord) and the ventral root (way out)
Sensory receptors in the skin move through peripheral nerves into the dorsal root ganglion, into the cell body and axon of sensory neurons. From the dorsal root interneurons connect to the ventral root, thus the axon of motor neuron, moves through spinal nerves, into the neuromuscular junction
Cauda equina
While the spinal cord ends at L2, the lumbar, sacral and coccygeal nerve roots, extend inferiorly to reach the point of spinal nerve exit from the vertebral column
-Conus medullaris, cauda equina, filum terminale
The spinal cord is protected by the
- ) Vertebral column
- ) Spinal meninges
- ) Cerebrospinal fluid
The spinal meninges
Are continuous with the brain meninges (dura, arachnoid and pia mater)
- Contain CSF within the subarachnoid space
- Provide stability and protection for the spinal cord
- Contain blood vessels that delver oxygen&nutrients to cord tissue
The spinal meninges location…
The dura and arachnoid mater extend beyond the end of the spinal cord (at L2) to the level of S2
A lumbar puncture (spinal tap)
Involves the insertion of a needle into the subarachnoid space beyond L3 (L4&L5)
- does not damage the spinal cord
- Is used to withdraw CSF for fluid for diagnostic testing or to reduce ICP
- May be used to administer medications
The spinal meninges are separated from the vertebral column by an
Epidural space
-Filled with adipose tissue and blood vessels
-Site of anaesthetic injection
Are secured to the spinal cord by denticulate ligaments
