The Nervous System Spinal Cord & Spinal Nerves. Anatomy – Chapter 14 & 16 (p. 432 - 439). The Central Nervous System. The CNS is well protected by bone, CT, and fluid. Meninges – Connective tissues that surround and protect the brain and spinal cord.
Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.
Anatomy – Chapter 14 & 16
(p. 432 - 439)
The CNS is well protected by bone, CT, and fluid
Meninges– Connective tissues that surround and protect the brain and spinal cord
Three layers: Dura mater, Arachnoid, Pia mater
Arachnoid– “spidery” web-like middle layer
Subarachnoid space – between arachnoid & pia mater; contains cerebrospinal fluid (CSF)
Lumbar cistern – area of subarachnoid space below the conus medularis; site for lumbar puncture (“spinal tap”)
cervical enlargement - supplies nerves to upper extremity
The dorsal & ventral roots of each segment come together at the intervertebral foramen (IVF) to form a mixed spinal nerve
Below the conus medularis, spinal nerves must angle downward (in the subarachnoid space) before exiting their IVF. These spinal nerves make up the cauda equina
The spinal cord has a narrow central canal surrounded by “horns” of gray matter connected by a commissure. Gray matter horns contain sensory & motor nuclei (groups of cell bodies).
Gray matter is surrounded by white matter “columns” which are made up of groups of myelinated axons creating organized ascending & descending tracts.
Anterior spinothalamic tract (ASTT) – crude touch & pressure
Lateral spinothalamic tract (LSTT) – pain & temperature
Anterior spinocerebellar tract (ASCT) & Posterior spinocerebellar tract (PSCT) –
Integrated with corticospinal pathways to allow for coordination of motor activity, maintenance of posture and muscle tone
Medial pathways – unconscious control over neck, trunk & proximal limb muscles for gross muscle movements
Lateral pathways – unconscious control over distal limb muscles for precise muscle movements
Tracts include: vestibulospinal, tectospinal, reticulospinal & rubrospinal
In order for sensory information to enter the spinal cord and ascend in a sensory tract, and for motor information to get from a descending tract to reach a skeletal muscle, impulses must travel through peripheral nerves (spinal nerves & cranial nerves)
Ventral ramus – provides motor control to muscles of extremities, anterior & lateral trunk; transmits sensations from all but skin of back; found at all spinal nerves
Rami communicantes(white ramus & gray ramus) – carry autonomic motor fibers (ANS) to smooth muscles & glands in ventral body cavity; transmit visceral sensations; only found at T1-L2 spinal nerves
Adjacent ventral rami will form complex interwoven networks of nerve fibers (axons) known as a nerve plexus
Four plexuses – cervical, brachial, lumbar, & sacral
Emerging from each plexus will be specifically named peripheral nerves, which will contain fibers from multiple spinal cord levels
Ventral rami from T2-T11 do not participate in a plexus. Instead they form individual intercostal nerves