Nerves MD3

Question 1

Brachial Plexus

Answer 1

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• Roots: C5 & C6, C7, C8 & T1
• Trunks: Superior, Middle, Inferior
• Divisions: Anterior (flexors), Posterior (extensors)
• Cords: Lateral, Posterior, Medial
• Branches: Musculocutaneous (lat), Median (lat & med), Ulnar (med), Axillary (post), Radial (post)
• also medial cutaneous nerve of arm & forearm (med)

Question 2

Axillary nn

Answer 2

• branch off posterior cord of brachial plexus
• C5 & C6
• shoulder abduction & shoulder sensation
• traverses quadrangular space

Question 3

Radial nn

Answer 3

• branches off of posterior cord of brachial plexus
• runs under brachioradialis
• C5-T1
• extension (elbow, wrist, fingers)

sensation to back of hand (radial/lateral aspect of fingers 1-4)

Question 4

Musculocutaneous nn

Answer 4

branch off lateral cord of brachial plexus

• C5-C6
• elbow flexion & chief supinator
• gives rise to lateral cutaneous nerve of forearm

Question 5

Median nn

Answer 5

branch off lateral & medial cords of brachial plexus

• C5-T1
• wrist & digit flexion, chief pronator, hand sensation (primarily)
• motor of hand (LOAF): lumbricals 1&2, opponens pollicis, abductor pollicis brevis, flexor pollicis brevis

Question 6

Ulnar nn

Answer 6

branch off of medial cord of brachial plexus

• C8 & T1
• hand intrinsics

Question 7

Long Thoracic nn

Answer 7

• C5-C7 (mainly 6 & 7) roots of brachial plexus
• supplies serratus anterior

Question 8

Suprascapular nn

Answer 8

• C5, C6 (5 mainly), branches off from superior trunk of brachial plexus
• supplies supra & infraspinatus
• passes through scapular notch under the transverse scapular ligament

Question 9

Thoracodorsal nn

Answer 9

C6-C8 (mainly 6 & 7), branch off from posterior cord of brachial plexus

-supplies latissimus dorsi

Question 10

Upper & Lower Subscapular nn

Answer 10

C5 & C6 (6 mainly)

• upper supplies only subscapularis
• lower supplies subscapularis & teres major

Question 11

Medial cutaneous nerve of the forearm

Answer 11

• C8 & T1, branches off from medial cord of brachial plexus (axilla)
• supplies anteromedial skin of forearm up to wrist

Question 12

Lateral Cutaneous Nerve of Forearm

Answer 12

from: musculocutaneous (C5, C6)

supplies skin of dorsolateral forearm

Question 13

Recurrent Median nn

Answer 13

from: median nn

supplies the thenar muscles

Question 14

Common Palmar Digital nn

Answer 14

from median nn (x 3) and ulnar nn (x 1)

supply lumbricals on adjacent sides of digits 2-4

Question 15

Proper Digital nn

Answer 15

branches off of common palmar digital nn,

runs on both sides of phalanges, supplies skin of distal phalanges?

Question 16

Dorsal Digital nn

Answer 16

from radial nn, and some ulnar nn

supplies skin on dorsal surface of proximal & middle phalanges

Question 17

Superficial & Deep Ulnar nn

Answer 17

from ulnar nn

deep supplies hypothenar, all interossei, lumbricals 4 & 5

superficial supplies palmaris brevis, skin on ulnar side of hand

Question 18

Interosseus nn

Answer 18

anterior (median nn) innervates deep muscles of anterior forearm (FDP, PQ, FPL)

posterior (radial nn ) innervates all muscles of posterior forearm

Question 19

Superficial branch of radial nn

Answer 19

supplies skin on the dorsolateral hand up to the proximal digits and proximolateral 4th digit

Question 20

Superficial Cluneal/Gluteal nn.

Answer 20

Superior & Middle: off of lateral branches of posterior rami (L1-S3)

Inferior: off of posterior cutaneous nn of thigh

-all innervate skin of buttocks (superior = superior buttock, middle = sacrum, inferior = inferior buttock)

Question 21

Superior Gluteal nn. (7)

Answer 21

branch off of sacral plexus

runs b/w glute medius & minimus, w/ superior gluteal aa.

superior branch supplies glute med, inferior branch supplies glute med, min, & TFL

Question 22

Inferior Gluteal nn.

Answer 22

branch off of sacral plexus

• superficial to sciatic nn., deep to glute max
• supplies glute max
• travels w/ inferior gluteal aa & vv.

Question 23

Sciatic nn.

Answer 23

off of sacral plexus

• has own arterial supply (branch off inferior gluteal aa)
• supplies all muscles of posterior thigh via tibial branch, except short head of biceps femoris (common peroneal branch)
• supplies all muscles of leg & foot, most skin of leg & foot, joints of lower limb
• splits into tibial & common peroneal nn.

Question 24

nn to quadratus femoris

Answer 24

• off of sacral plexus, anterior to sciatic nn & obturator internus, posterior to hip joint
• supplies hip joint, inferior gemellus, quadratus femoris

Question 25

nn to Obturator Internus

Answer 25

branch off sacral plexus (anterior division of anterior rami), runs parallel course to pudendal nn. -supplies superior gemellus, obturator internus

Question 26

Pudendal nn. (2)

Answer 26

- branch off of sacral plexus, exits greater sciatic foramen, wraps around sacrospinous ligament, enters back in via lesser sciatic foramen - suppies perineum - most medial structure to pass thru GSF

Question 27

Posterior Cutaneous nn of Thigh

Answer 27

- supplies skin of inferior buttocks, posterior thigh, popliteal fossa, upper medial thigh, lateral perineum - branch off sacral plexus, exits GSF deep to glute max & inferior to piriformis, descends posterior thigh beneath fascia lata

Question 28

Deep Peroneal nn.

Answer 28

- branch off common peroneal, runs anteriorly w/ anterior tibial aa. - runs through extensor digitorum longus lesion-\> drop foot (no dorsiflexion)

Question 29

Superficial Peroneal nn.

Answer 29

branch off common peroneal, lateral side of leg, continues to supply skin of dorsal foot

Question 30

Tibial nn.

Answer 30

larger branch off sciatic nn. runs b/w heads of gastroc (supplies posterior leg), runs w/ popliteal aa., runs b/w flexor hallucis longus & flexor digitorum longus near ankle -splits into medial & lateral plantar nn in bottom of foot

Question 31

Saphenous nn.

Answer 31

largest/longest branch of femoral nn. passes anterior to medial malleolus supplies cutaneous innervation to medial lower leg & medial foot

Question 32

Superficial Peroneal nn.

Answer 32

branch off common peroneal nn. supplies motor innervation to lateral leg, cutaneous innervation to most of dorsum of foot & anterolateral leg (2) -ALPs in the DiSTance anterior compartment of leg: deep peroneal nn lateral: superficial peroneal nn posterior: tibial nn

Question 33

Deep Peroneal nn.

Answer 33

branch off of common peroneal nn. supplies motor to anterior leg, all extensors supplies cutaneous innervation to webbing b/w 1st and 2nd toes (3)

Question 34

Medial Plantar nn.

Answer 34

branch off of tibial nn., larger than lateral, analogous to median nn in hand supplies motor to Abductor hallucis, FDB, FHB, lumbrical #1 supplies cutaneous innervation to medial 3.5 digits of sole of foot -more skin, less muscle (4)

Question 35

Lateral Plantar nn.

Answer 35

branch off of tibial nn. deep to abductor hallucis, analogous to ulnar nn in hand more muscle, less skin supplies motor to all muscles in sole of foot except those by medial plantar nn (1st lumbrical, abductor hallucis, FDB, FHB) supplies cutaneous innervation to lateral 1.5 digits (5)

Question 36

Lower extremity myotomes

Answer 36

L2-\> S2 (joint movements toward inspector down leg, then back up leg away) L2: hip flexion L3: knee extension L4: dorsiflexion L5: great toe extension S1: plantar flexion/eversion S2: knee flexion Patellar DTR (L4), Achilles DTR (S1)

Question 37

Nerves near Hip Joint

Answer 37

_Lumbar Plexus_ **Femoral** -quadriceps femoris, iliopsoas, pectineus, sartorius **Obturator** -adductors (magnus, longus, brevis), gracilis, pectineus, obturator externus _Sacral Plexus_ **nn to quadratus femoris** -inferior gemellus, quadratus femoris **nn to obturator internus** -obturator internus, superior gemellus **superior gluteal** -glute min & medius, tensor fascia latae **inferior gluteal** -glute max

Question 38

Nerves near knee joint

Answer 38

**Sciatic nn** from lumbar & sacral plexus splits into common peroneal & tibial nn @ apex of popliteal fossa - **common peroneal** wraps around lateral fibular neck, susceptible to injury (superficial), gives rise to lateral sural cutaneous (skin posterolateral leg) - splits into **superficial (lateral leg: peroneus longus & brevis) & deep peroneal (anterior leg: tom dick & harry, dorsal foot) nn.** - **tibial nn** supplies muscles of back of leg (popliteus too) & plantar foot

Question 39

Overview of lower extremity nn

Answer 39

**Femoral nn** (anterior thigh (quads, pectineus, iliopsoas, sartorius) -\> **saphenuos nn** -anterior **Sciatic nn**-\> **common peroneal (superficial & deep peroneal) & tibial (lateral & medial plantar)** -posterior

Question 40

Lower extremity dermatomes

Answer 40