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Flashcards in Innervation of Extremities Deck (47):
1

Brachial Plexus

Roots (5) = C5-T1
Trunks (3) = Upper, middle, lower
Divisions (6)
Cords (3) = lateral, medial, posterior
Terminal Branches (5) = musculocutaneous, median, ulnar, radial, axillary

2

Randy Travis Drinks Cold Beer

Roots
Trunks
Divisions
Cords
Branches

3

Roots

C5
C6
C7
C8
T1

4

Trunks

upper = C5, C6
middle = C7
lower = C8, T1

5

musculocutaneous nerve (C5-C7)

injury = upper trunk compression, shoulder dystocia
motor deficit = biceps, brachialis, coracobrachialis, flexion of arm at elbow
"Erb-Duschenne Palsy" - "waiter's tip"
sensory deficit = lateral forearm

6

axillary nerve (C5, C6)

location = lateral edge of the shoulder
innervates the deltoid = abduction at the shoulder
injury = fracture of surgical neck of humerus or needle injection
motor deficit = loss of deltoid muscle
sensory loss = over deltoid muscle

7

median nerve (C5-T1)

injury - supracondylar fracture of humerus
pronator teres syndrome
proximal injury = supracondylar humorous fracture; pronator teres syndrome
motor deficit = lateral finger flexion, wrist flexion, thumb opposition ("ape hand") *proximal and distal injury
sensory deficit= dorsal and palmar lateral 3.5 digits
thenar eminence = innervated by median nerve branch PROXIMAL to carpal tunnel

8

radial nerve (C5-T1)

injury
proximal = axilla injury (compression from crutches)
"Saturday night palsy"
motor deficit = wrist drop, triceps weakness
distal = fracture of midshaft of humerus (nerve runs in radial groove)
aggressive stretching of the forearm with radial subluxation (dislocation of radius) and radial nerve injury
motor deficit = wrist drop ONLY
sensory deficit = loss of sensation over posterior arm and dorsum of the hand and thumb

9

ulnar nerve (C8, T1)

injury = medial epicondyle of humorus
repetitive minor trauma (funny bone)
proximal injury = fracture of medial epicondyle
motor deficit= medial finger flexion, medial ulnar wrist flexion (radial deviation noted with wrist flexion)
sensory deficit = medial 1.5 fingers & hypothenar eminence
distal injury = hamate hook fracture (fall on outstretched hand)
motor deficit = extension of 4th and 5th fingers - lumbrical muscle impairment
"ulnar claw hand", "pope's blessing" = 4th and 5th fingers can't fully extend

10

lateral antebrachial cutaneous nerve

branch from musculocutaneous nerve - lateral cord
fxn: sensory innervation to the lateral forearm

11

medial antebrachial cutaneous nerve

branches off the medial cord - before ulnar branch
fxn: sensory innervation to medial forearm

12

upper trunk injury

etiology: violent stretch of the upper brachial plexus
Shoulder dystocia: neonatal injury during delivery
Sports injury: following a fall, landing onto the area between the head and shoulder

13

lower trunk injury of brachial plexus

cervical rib: congenital extra rib compresses lower trunk
pancoast tumor of lung = tumor at the apex of the lung

14

anterior interosseous nerve

branch of median nerve
distal injury = compression from hemorrhage or hematoma, following radius or ulnar fracture

15

median nerve carpal tunnel

carpal tunnel syndrome - median nerve injury
entrapment of median nerve in carpal tunnel
nerve compression --> paresthesia, pain, and numbness in distribution of median nerve

16

sensory innervation of upper extremities

Dermatomes
C4, C5 = shoulder
C6 = lateral forearm
T1 = medial forearm
T2 = Axilla

17

sensory innervation shoulder

C4, C5
C5 = axillary nerve

18

sensory innervation lateral forearm

C6 = lateral antibrachial cutaneous nerve

19

sensory innervation medial forearm

T1 = medial antibrachial cutaneous nerve (medial cord)

20

sensory innervation axilla

T2

21

sensory innervation of palmar hand

lateral 3.5 digits = MEDIAN NERVE (C7)
medial 1.5 digits = ULNAR NERVE (C8)

22

sensory innervation of dorsal hand

tips of lateral 3.5 digits = MEDIAN NERVE (C7)
lateral 3.5 digits = RADIAL NERVER (C6)
medial 1.5 digits = ULNAR NERVE (C8)

23

ape hand injury

proximal or distal median nerve injury
motor deficit: loss of opponents pollicis muscle = unopposable thumb

24

Erb-Duchenne Palsy

"waiter's tip"
loss of arm abduction = held by side
paralysis of lateral rotators = held medially rotated
loss of biceps function = forearm held in pronation
injury to C5 to C6 = musculocutaneous, axillary and radial nerve injury

25

Klumpke's palsy

injury to lower trunk of brachial plexus (C8 to T1)
cervical rib
pancoast tumor = apex tumor of lung
abduction injury = sudden upward pull of arm
**thoracic outlet syndrome

26

thoracic outlet syndrome

compression of the neuromuscular bundle entering the thoracic cavity
affects: C8 & T1, subclavian artery and vein
1. thenar and hypothenar eminence atrophy (median and ulnar nerve injury)
2. interosseous muscle atrophy (ulnar nerve)
3. sensory deficits of medial forearm and hand (ulnar n.)
4. radial pulse disappears with ipsilateral head turn (subclavian artery)

27

lumbrical muscles

function: flexion of the metacarpal phalangeal (MCP) joint
extend the distal interphalangeal (DIP) and proximal interphalangeal (PIP) joints

28

ulnar claw injury

distal ulnar nerve lesion
loss of 4th and 5th digit lumbrical function
"Pope's blessing"
loss of flexion at MCP
loss of flexion and extension at PIP and DIP in 4th and 5th digits

29

median claw injury

distal median nerve (post carpal tunnel)
motor deficit: loss of lateral lumbrical function (2nd and 3rd digits)
loss of flexion at MCP
loss of flexion and extension at PIP and DIP
function normal in 4th and 5th digits

30

Klumpke's total claw

lower trunk of brachial plexus (C8 and T1)
motor deficit: loss of function of all lumbrical muscles (2nd -5th digits)
loss of extension (clawing) of ALL digits

31

long thoracic nerve injury

C5, C6, C7 roots
innervates = serratus anterior - anchors scapula to thoracic cage
injury = winged scapula and ipsilateral lymphedema

32

lubroscaral plexus

nerve roots of the lumbar and sacral spine
FEMORAL N. = L2-L4
OBTURATOR N. = L2-L4
SUPERIOR GLUTEAL N. = L4-S1
INFERIOR GLUTEAL N. = L5-S2
COMMON FIBULAR N. = L4-S2
TIBIAL N. = L4-S3
SCIATIC N. = L4-S3

33

Femoral Nerve

L2-L4 nerve roots
injury = fracture of pelvis
motor deficit = thigh flexion and leg extension
sensory deficit = anterior thigh and medial leg

34

Obturator Nerve

L2-L4
injury = anterior hip dislocation - externally rotated & abducted hip
femoral artery injury ass
motor deficit = thigh adduction
sensory deficit = medial thigh

35

common peroneal nerve

L4-S2
branch of sciatic nerve
injury - trauma to lateral aspect of leg or fibular neck fracture
motor deficit = foot eversion and dorsiflexion, toe extension, foot drop, foot slap, stoppage gait
sensory anteriolateral leg and dorsal aspect of foot

36

Tibial Nerve

L4-S3
branch of sciatic nerve
injury - knee trauma
motor deficit -foot inversion and plantar flexion; toe flexion
sensory deficit - sole of foot

37

superior gluteal nerve

L4, L5, S1
gluteus medius muscle
gluteus minimus muscle
injury = posterior hip dislocation (car accident) ass. w/ avascular necrosis of hip; polio
motor deficit = thigh abduction (positive Trendelenburg sign)

38

inferior gluteal nerve

L5-S2
innervates gluteus maximus muscle
can't jump, climb stairs, or rise from seated position, can't push inferiorly (downward)

39

trendelenburg sign

superior gluteal nerve injury (gluteus minimus and medius)
contralateral hip drops when standing on leg ipsilateral to site of injury

40

ankle anatomy

talus bone = joins navicular bone
calcaneus bone = joins cuboid bone

41

inversion ankle injury

anterior talofibular ligament - links talus bone to fibula
fibula fracture
avulsion of 5th metatarsal

42

eversion ankle injury

less common than inversion due to strong deltoid ligament (covers medial aspect of ankle joint)
- avulsion of medial malleous OR
fibular fracture

43

calcaneous fracture

fall onto the heels from high height

44

common fibular nerve

branches into the deep fibular nerve and superficial fibular nerve

45

deep fibular nerve

innervates muscle in anterior compartment of the leg that extends the big toe and dorsiflex (extend) the foot
damage = foot-drop

46

superficial fibular nerve

innervates most of the skin of the dorsum of the foot

47

sural nerve

cutaneous branch of the tibial and common fibular nerves tat innervates skin of the posterior leg