The spinal cord’s own motor responses: a stretched muscle contracts, a muscle under strong tension relaxes, and a painful stimulus makes a limb pull away while the opposite limb braces. Your book says long essays are rarely set from this chapter; it is a short-note chapter, and the stretch reflex is the one asked most, followed by the inverse stretch and withdrawal reflexes.
Topics, in the book’s order
- Stretch reflex · pp. 1054–1056 · asked 5 times
- Inverse stretch reflex and muscle tone · pp. 1056–1057 · asked once
- Withdrawal reflex · pp. 1057–1058 · asked once
- Properties of spinal reflexes · p. 1059
When you’ve read them: Quiz 128 · Spinal Reflexes, 15 questions.
After this chapter you should be able to
- name the spinal reflexes: stretch (phasic and tonic), inverse stretch, and withdrawal with crossed extension
- draw the arcs of the stretch and inverse stretch reflexes, and explain what each does for movement and posture
- explain why the withdrawal reflex matters
- list the differences between the stretch and withdrawal reflexes
- explain how afterdischarge arises in the withdrawal reflex, and what it is for
- list the properties of spinal reflexes
- explain how inhibition works in the spinal cord
Going further: the properties of spinal reflexes in detail, and the part spinal reflexes play in motor control.
Viva checklist
- The spinal reflexes, by name
- Stretch reflex: receptor, afferent, number of synapses and response
- Phasic vs tonic stretch reflex
- Reciprocal innervation and reciprocal inhibition
- What brisk or depressed jerks say about the γ motor neurons
- Inverse stretch reflex: receptor, afferent, and why it is disynaptic
- Spindle measures length; tendon organ measures tension
- Clasp-knife phenomenon and the lengthening reaction
- The mechanism of clonus
- Crossed extensor (Phillipson’s) reflex
- Special features of the withdrawal reflex: protective, prepotent, local sign, afterdischarge
- The two mechanisms of afterdischarge
- Stretch vs withdrawal reflex: at least five differences
- Summation, occlusion, convergence and divergence; the types of inhibition