Upper - Clinical

Question 1

what are HOX genes

Answer 1

complex interplay of gene activation and transcription via many growth and signalling proteins
make sure the boys is in the right places etc, layout of the body

Question 2

what do the somites develop into

Answer 2

limb muscle

Question 3

what does the lateral plate mesoderm develop into

Answer 3

limb bones and connective tissue

Question 4

what are the two divisions of the somites

Answer 4

ventral sclerotome - vertebral column

dorsolateral dermomyotome - dermatome (dermis of skin) and myotome - skeletal muscles

Question 5

the ventral part of a myotome migrates into limb buds and divides into what two buds

Answer 5

anterior part - muscles of the front of the limb ( flexors)

posterior part - muscles of the back of the limb extensors

Question 6

what is the upper limb innervated by

Answer 6

branches of the ventral primary rami of nerves C5 to T1

Question 7

what are the 3 axis of limb development

Answer 7

proximodistal - from the shoulder to the hand (from hip to foot)
craniocaudal - the thumb is the most cranial and the little finger is the most caudal
dorsoventral - the palm of the hand and sole of the foot are ventral and the back of the hand and top of the foot are the dorsal

Question 8

what is FGF10

Answer 8

fibroblast growth factor which is secreted by mesenchymal core of the limb bud which induces thickening to the overlying ectoderm

Question 9

what is the progress zone

Answer 9

area of mesenchymal cells underlying the apical ectodermal ridge (AER)
this area maintains proximodistal outgrowth of the limb

Question 10

what happens when AER is interrupted or removed

Answer 10

inhibits proximodistal outgrowth and forms deformities

Question 11

what is amelia and meromelia

Answer 11

a - complete absence of limb

m - partial absence of limb

Question 12

what is supernumerary limbs

Answer 12

ectopic FGF causes growth of another limb

Question 13

what happens when the central part of the AER fails

Answer 13

caused cleft hand or foot

Question 14

what is polydactyly

Answer 14

craniocaudal issue

extra fingers or toes

Question 15

what is nail patella syndrome

Answer 15

defect in LMX1B - abnormality of the nail with small, absent or irregular patellae

Question 16

what is syndactyly

Answer 16

dorsoventral issue

fused digits due to failure of normal apoptosis

Question 17

what are some causes of limb abnormalities

Answer 17

genetics - herediatary or spontaneous 
drugs 
environmental poisons 
maternal illness
amniotic band syndrome

Question 18

what is phocomelia

Answer 18

malformation which was caused by thalidomide
digits develop prematurely
proximal elements of limb absent
it inhibits expression of FGF10 and 8 and is thought to inhibit angiogenesis - prevents proximodistal lengthening of the limbs

Question 19

describe anterior shoulder dislocation and the risks

Answer 19

most common - axillary nerve implicated - first posterior branch of brachial plexus goes behind surgical head - movement of head causes damage to nerve
axillary supplies deltoid
loss of C5-6 sensation (upper limb lateral arm)

Question 20

describe midshaft humeral fracture and the risks

Answer 20

20% associated with nerve damage - radial nerve runs in radial groove - risk of damage
inability of extensors of arm and wrist

Question 21

who are more affected by supracondylar humeral fractures and the risks

Answer 21

common in children

distal humeral fracture

Question 22

what are fat pads

Answer 22

visible anterior small ones are normal
- large anterior fat pads indicate fracture
small or large on posterior indicates fracture

Question 23

what are ossification centres

Answer 23

ends of long bones in children aged 2-10 may be misinterpret as fractures

Question 24

what is a colles’ fracture

Answer 24

distal radius fracture but dorsal displacement fragment

Question 25

what is a smith fracture

Answer 25

opposite of colles - fall on flexed hand (uncommon) distal radius fracture where the dorsal displacement goes palmar

Question 26

what is a carpal bone fracture and what are the risks

Answer 26

missing carpal bone fracture is most common cause of litigation
include scaphoid fracture
risk of avascular necrosis of radiocarpal joint
(no fat pads to indicate fracture in wrist)

Question 27

what is a dermatome

Answer 27

skin region innervated by a single nerve or vertebral level

Question 28

what is a myotome

Answer 28

muscle/groups innervated by a single nerve or vertebral level

Question 29

what can cause brachial plexus damage

Answer 29

injuries at birth
blunt trauma
penetrating wounds into axilla or neck
disease

Question 30

what are the different diseases of upper and lower brachial plexus injury

Answer 30

superior - C5/6 - erbs palsy

inferior - C8, T1 - klumpkes palsy

Question 31

what part of the brachial plexus will 1st rib injuries cause compared to cervical cord injuries

Answer 31

1st rib - affect trunks

CC - affects roots

Question 32

what is erbs palsy

Answer 32

excessive starching of neck during delivery - damage C5/6
often due to shoulder dystocia
paralysis of shoulder and arm muscles supplied by C5/6 (axillary and musculocutaneous)
causes atrophy of deltoid, biceps and lateral rotator shoulder

Question 33

how do you acquire erbs palsy as an adult

Answer 33

falls on side of head and shoulder forcing apart - motorbike accidents
MRI shows nerve damage

Question 34

what is klumpkes palsy in children

Answer 34

damage to inferior trunk of plexus ie c8 and t1 - ulnar nerve
less common than erbs
occurs in delivery if upper limb is excessively pulled

Question 35

how does klumpkes palsy get acquired in adults

Answer 35

when upper limb is suddenly pulled superiorly - graphing to prevent fall
MRI shows rot damage

Question 36

what does the ulnar nerve innervate and therefore what muscles are affected by klumopke palsy

Answer 36

nothing in the arm
forearm - FCU, medial half of FDP
in hand - hypothenar eminence, adductor pollicis, all interossei, medial 2 lumbricals

Question 37

what areas of the skin does klumpkes palsy affect

Answer 37

ulnar nerve damage which provide sensation to medial side of hand and forearm

Question 38

what is klumpkes palsy commonly associated with

Answer 38

horners syndrome (ptosis, mitosis, anhidrosis, vasodilation) 
T1 provides some sympathetic input to head and may be damaged