Chapter 12 - Spinal cord, meninges, tissue Flashcards
Conus medullaris
Tapered inferior end of spinal cord
Cauda equina
Origins of spinal nerves extending inferiorly from lumbosacral enlargement and conus medullaris
Layers of meninges (superficial to deep)
-Dura mater
-Arachnoid mater
-Pia mater
Dura mater
-Layer of CT around spinal cord
-Continuous with the epineurium of spinal nerves
-Most superficial layer
Arachnoid mater
-Layer of CT around spinal cord
-Thin and wispy
-Middle layer
Pia mater
-Layer of CT around spinal cord
-Bound tightly to surface of brain and spinal cord
-Deepest layer
Epidural space
-Space between periosteum and dura mater
-Contains blood vessels, areolar CT, and fat
Subdural space
-Space between dura mater and arachnoid mater
-Contains serous fluid
Subarachnoid space
-Space between arachnoid mater and pia mater
-Contains CSF and blood vessels within web-like strands of arachnoid tissue
Commissures
Connections between left and right halves of the spinal cord
Roots
-Spinal nerves arise as rootlets, then combine to form roots
-Dorsal and ventral root that merge laterally to form a spinal nerve
-Dorsal root has a ganglion
Components of the reflex arc
-Sensory receptor
-Sensory neuron
-Interneuron
-Motor neuron
-Effector organ
Stretch reflex
-Muscles contract in response to a stretching force applied to them
-No interneuron
Golgi tendon reflex
-Prevents contracting muscles from applying excessive tension to tendons
-Prevents damage to tendons
-Produces sudden relaxation of muscles
Withdrawal reflex
-Removes a body part from a painful stimulus
-Reciprocal innervation
Reciprocal innervation
-Causes relaxation of extensor muscle when flexor muscle contracts
-Involved in stretch and withdrawal reflexes
Endoneurium
Layer of CT that surrounds individual neurons
Perineurium
Layer of CT that surrounds axon groups to form fasicles
Epineurium
Layer of CT that surrounds the entire nerve
Dorsal ramus
Innervates deep muscles of the trunk responsible for movements of the vertebral column, and CT/skin near the midline of the back
Ventral ramus
What they innervate depends on which part of the spinal cord is being considered
Cervical plexus
-C1-C4
-Innervates superficial neck structures, skin of neck, posterior portion of head
-Ansa cervicalis
-Phrenic nerve
Phrenic nerve
-In cervical and brachial plexuses
-C3-C5
-Innervates diaphragm
Brachial plexus
-C5-T1
-5 ventral rami form 3 trunks that split into 6 divisions that form cords that give rise to 5 nerves
-Branches: Axillary, radial, musculocutaneous, ulnar, median, etc