spinal cord

Question 1

gross anatomy of spinal cord

Answer 1

• Cylindrical in shape -~45cm long, 2cm diameter
• Spinal cord is shorter than the vertebral column
• Covered by meninges and enclosed by the vertebral column
• Filum terminale anchors the spinal cord to the coccyx

Question 2

spinal nerves

Answer 2

• Arising from the spinal cord are 31 pairs of spinal nerves (these branch extensively and constitute the peripheral nervous system)
• Points of attachment to the cord are called Roots
• Posterior (dorsal) root - afferent (sensory)
• Anterior (ventral) root - efferent (motor)

Question 3

functions of spinal cord

Answer 3

• A link between the brain and the rest of the body -a function of the white matter
• Participation in neural responses -SPINAL REFLEXES -a function of the gray matter

Question 4

sensory and motor tracts

Answer 4

• White matter divided into tracts
• Links between the brain and the periphery
• Ascending (Sensory) tracts convey impulses to the brain
• Descending (Motor) tracts convey impulses from the brain

Question 5

spinothalamic tract

Answer 5

• cross in spinal cord
• crude touch, pain, temperature sensation to brain

Question 6

dorsal column pathway

Answer 6

• cross in medulla
• information about joint sense and fine discriminatory touch

Question 7

spinal reflexes

Answer 7

• Gray matter serves as an integrating centre for spinal reflexes
• Reflexes are fast, predictable automatic responses to stimuli in the environment
• Somatic reflexes, which result in muscle movement are the most obvious type

Question 8

components of a reflex

Answer 8

• Receptor
• Afferent Neuron
• Integrating Centre
• Efferent Neuron
• Effector

Question 9

stretch reflex

Answer 9

• A simple monosynaptic reflex
• Muscle stretch is detected by muscle spindles
• Afferent neurons synapse directly with motor neurons.
• Motor neurons are activated resulting in muscle contract which returns it back to its original length
• Simple spinal reflexes
(a) Stretch reflex e.g. knee jerk. This is a monosynaptic reflex
(b) Withdrawal reflex -polysynaptic reflex

Question 10

crossed exterior reflex

Answer 10

• Polysynaptic, contralateral, intersegmental reflex
• Stepping on a pin
• Flexor muscles of the thigh contract and withdraw the leg from the painful stimulus
• At the same time, the extensor muscles on the other leg contract allowing all the weight of the body to be supported on one leg