Thoracic, Lumbar, and Sacral spinal nerves

Question 1

thoracic spinal nerves

Answer 1

each mixed nerve will divide into a posterior and anterior primary ramus

Question 2

posterior primary ramus

Answer 2

divides into medial and lateral branch
medial branch - motor and sensory function, supply
semispinalis (upper 6), longissimus (lower 6), multifidi, and sensory to the skin paraspinally
lateral branch - increase in size from superior to inferior, also motor and sensory, supply - longissimus, iliocostalis, levator costarum, and provide sensory innervation to the skin near the costal angle

Question 3

anterior primary ramus

Answer 3

anterior primary ramus follow the course of the rib above the nerve. each intercostal nerve gives off a lateral cutaneous branch which divides into an anterior and posterior branch that supplies the overlying skin.
intercostal nerves supply the following muscles - internal intercostals, external intercostals, seratus posterior, transversus thoracis, transverse abdominal (7-11), internal abdominal oblique (7-11), external abdominal oblique (7-11), rectus abdominus (7-11)

Question 4

intercostobrachial nerve

Answer 4

anterior primary rami of T2 and sometimes T1

Question 5

Subcostal nerve

Answer 5

T12, is the largest of the thoracic nerves and also contributes to the lumbar plexus. may supply skin as far inferior as the superior buttocks

Question 6

thoracic communication

Answer 6

each thoracic nerve communicates with the sympathetic trunk by both grey and white rmus comunicans grey ramus is medial to white ramus

Question 7

lumbar spinal nerves

Answer 7

each lumbar root divides into anterior and posterior primary ramus
posterior - divide into medial and lateral branches. medial supplies multifidi
lateral supplies erector spinae group
anterior - contribute to the lumbar and sacral plexus

Question 8

lumbar Sympathetic communication

Answer 8

4 lumbar sympathetic ganglia

white ramus communicans associated with L1 and L2, grey ramus communicans associated with all lumbar nerves

Question 9

sacral spinal nerves

Answer 9

nerves descend inside dura and form much of the cuada equina

divide into an anterior and posterior primary ramus

Question 10

sacral posterior primary ramus

Answer 10

S1 - S3 posterior rami divide into medial and lateral branches
medial branches - supply adjacent multifidi
lateral branches - sensory supply to skin over buttocks (with L5 and S4)
S4 and S4 unit with the coccygeal posterior rami and supply the skin over the coccyx

Question 11

sacral spinal nerves

Answer 11

nerves descend inside dura and form much of the cuada equina

divide into an anterior and posterior primary ramus

Question 12

sacral posterior primary ramus

Answer 12

S1 - S3 posterior rami divide into medial and lateral branches
medial branches - supply adjacent multifidi
lateral branches - sensory supply to skin over buttocks (with L5 and S4)
S4 and S4 unit with the coccygeal posterior rami and supply the skin over the coccyx