Chapter 13 - Spinal Cord & Reflexes Flashcards
4 Functions of the Spinal Cord
- Conduction
- Neural Integration
- Locomotion
- Reflexes
Conduction
nerve fibers send sensory and motor information ↑ and ↓ the spinal cord.
Neural integration
spinal neurons receive input from multiple sources, integrate (compute!) it, and execute appropriate output (e.g., bladder control)
Locomotion
spinal cord contains central pattern generators. Ex. groups of neurons that coordinate repetitive sequences of contractions for walking.
Reflexes
involuntary responses to stimuli that are vital to posture, coordination, and protection.
Spinal Cord
cylinder of nervous tissue that arises from the brainstem at the foramen magnum of the skull.
– Occupies the upper 2/3 of vertebral canal
– Inferior margin of SC ends at the L1 vertebral bone or slightly beyond!!!!
The Spinal Cord
- Cervical 8
- Thoracic 12
- Lumbar 5
- Sacrum 5
1 Coccygeal nerve
Why are there 8 cervical nerves, but only 7 cervical vertebrae (bones) ?
Cl nerve comes out between the skul and first vertebrae. Then there numbered after that
Why is there little risk of spinal cord damage with these procedures?
The spinal cord does not extend lower than L1/L2
Surface Anatomy
31 pairs of spinal nerves enter/exit between the vertebrae on both sides.
Cervical Enlargement
- nerves to upper limb
- takes care of the arm
Lumbar enlargement
- nerves to pelvic region and lower limbs
- for your legs, sensory and motor regions make this place larger
Medullary cone
- cord tapers to a point inferior to lumbar enlargement
- tip of spinal cord
Cauda equina
- bundle of nerve roots that occupy the vertebral canal from L2 to S5
- horse tail. bunch of nerves coming down from cone
Where are the Enlargements?
In the cervical & Lumbar regions
- skinner in thoracic because you have neuron that controls posture, core muscles.
- in very large motor unit groups
P.A.D.
-Pia mater
- Arachnoid mater
- Dura mater
- These same 3 fibrous membranes surround the spinal cord
Dural sheath
surrounds spinal cord and is separated from vertebrae by epidural space.
Arachnoid
membrane adheres to dura and is separated from pia by fibers spanning the subarachnoid space that is filled with cerebrospinal fluid (CSF)
Lumbar puncture
spinal tap) takes sample of CSF
Pia
delicate membrane that follows contours of spinal cord.
Safe place to do lumbar puncture
L3/L4 or L4/L5
Spina Bifida
congenital defect in which one or more vertebrae fail to form a complete vertebral arch for enclosure of the spinal cord.
Prevention of Spina Bifida
Folic acid (a B vitamin now added to flour), also in prenatal vitamins
– Note:
Defect occurs during the first 4 wks of devel., so folic acid supplements for mothers must begin 3 mo. before conception.
Gray Matter
neuron cell bodies with little myelin
– Site of information processing, synaptic integration