BT_RA 1.7 Describe the pain and sensory pathways

T/F  the sensory pathway (including pain) consists of three separate neurons: 1. periphery to spinal cord, 2. spinal cord to thalamus, 3. thalamus to cortex (see also Discussion Point 1)

T/F  sharp, well localised pain is transmitted via A-delta nerve fibres

T/F  C fibres are polymodal, and respond to thermal, chemical and mechanical stimuli

T/F  C fibres synapse in the dorsal horn at laminae I and II

T/F  all sensory information (including pain) is transmitted in the spinal cord via the spinothalamic tract

T/F  the primary sensory cortex (in the brain) lies anterior to the primary motor cortex

References:

1. Kam & Power 3rd edition Chapter 13
2. Ganong 24th Edition Chapter 8

Discussion Point 

• does this basic scheme still apply for sensation/pain transmitted via cranial nerves?

SS_OB 1.8 Describe the anatomy and physiology of pain in labour and childbirth

T / F  Pain associated with the first stage of labour is visceral pain – dull, poorly localised, and felt in the lower abdomen or back. It is caused by cervical dilation, and increasing pressure in the lower uterine segment.

T / F  Nociception in the first stage occurs via A-delta and C fibres that travel with the sympathetic efferents. They eventually enter the neuraxis via the T10 – L1 nerve roots.

T / F  Pain associated with the second stage of labour is predominantly somatic pain – localised to the perineum. It is caused by stretching and tearing of the vagina and perineal skin.

T / F  Nociception in the second stage is transmitted via the pudendal nerves, which enter the neuraxis via the S2 – S4 nerve roots.

T / F  An epidural block to T10 would be adequate for labour, but needs to be extended to T4 for a Caesarian, in order to cover most of the peritoneal contents.

T / F  Ice is used to assess an epidural or spinal block, because input from thermoreceptors is transmitted via the same A-delta and C fibres that transmit pain.

References:
1. Macintyre etal. Clinical Pain Management: Acute Pain, 2nd edition 2008, Chapter 26.
2. Guyton 12th edition, Fig 46-6

 

BT_RA 1.5 Describe the dermatomal innervations

Not a very exciting post today, I’m afraid. Some key facts in medicine just have to be rote learned.

T/F   the back of the neck is supplied by C2

T/F  the thumb is supplied by C7

T/F  the inguinal crease is supplied by T12

T/F  the sole of the foot is supplied by L5

T/F  the posterior thigh is supplied by S2