Brachial Plexus

Front 1

Define plexus.

Back 1

area of the peripheral nervous system where there is branching & interconnecting of nerves, resulting in redistribution of nerve fibres.

Front 2

What does each spinal nerve have to make up its common root?

Back 2

dorsal root = sensory root of the nerve
ventral root = motor root of the nerve

Front 3

What does the common root of a spinal nerve branch into?

Back 3

posterior primary ramus - small, innervates trunk overlying spinal column
anterior primary ramus - has majority of nerve fibres

Front 4

does the anterior or posterior primary ramus innervate most activity of a particular segmental nerve?

Back 4

anterior primary ramus - has the majority of nerve fibres

Front 5

name 2 areas where anterior primary rami distribution is modified as they go out to limbs.

Back 5

brachial plexus
lumbrosacral plexus

Front 6

Which nerve roots are involved in the brachial plexus?

Back 6

C5 6 7 8 + T1

Front 7

which roots merge to become trunks?

Back 7

C5+6 - upper trunk
C7 - middle trunk
C8+T1 - lower trunk

Front 8

What parts of the brachial plexus pass behind the clavicle?

Back 8

trunks

Front 9

What does each trunk divide into as it enter the axilla?

Back 9

anterior + posterior divisions

Front 10

What do the divisions merge into to form?

Back 10

cords

Front 11

Which divisions make up the lateral, medial & posterior cords?

Back 11

lateral - 2 upper/lateral anterior divisions
medial - anterior lower/medial divisions
posterior - 3 posterior divisions, in the middle of the other 2 cords

Front 12

What do the cords become?

Back 12

branches that are peripheral nerves of the upper limb

Front 13

List the changes in name of the brachial plexus

Back 13

roots trunks divisions cords branches

Front 14

What are cords named in relation to?

Back 14

axillary artery

Front 15

What is the most vital area of the plexus anatomically and what part lies in this region?

Back 15

axilla - cords lie here

Front 16

What are the 2 branches from the roots?

Back 16

dorsal scapular nerve (C5)
long thoracic nerve (C5,6+7)

Front 17

Only the upper trunk has branches. What are these 2?

Back 17

suprascapular nerve
insignificant nerve to subclavius

Front 18

What branches do divisions have?

Back 18

None, they only redistribute fibres into cords

Front 19

What are branches mostly named in relation to?

Back 19

which cord they arise from

Front 20

upper middle lower or lateral medial posterior or anterior posterior, which are cords, which are divisions and which are trunks?

Back 20

trunks - upper, middle, lower
cords - lateral, medial, posterior
divisions - anterior, posterior

Front 21

What are the 3 branches coming off the lateral cord?

Back 21

lateral pectoral nerve
lateral head of median nerve
musculocutaneous nerve

Front 22

What are the 5 branches of the medial cord?

Back 22

medial pectoral nerve
2 cutaneous nerves - arm + forearm
medial head of median nerve
ulnar nerve

Front 23

what are the 5 branches of the posterior cord/

Back 23

upper + lower subscapular nerve
thoracodorsal nerve
axillary nerve
radial nerve

Front 24

what is the main single branch of the lateral cord?

Back 24

musculocutaneous nerve

Front 25

Describe the distribution of the musculocutaneous nerve

Back 25

arises from lateral cord
enters coracobrachialis
arises deep to biceps, superficial to brachialis & supplies these elbow flexors
becomes lateral cutaneous nerve lateral & proximal to elbow joint
no motor function below this point

Front 26

Name 4 functions of musculocutaneous nerve

Back 26

elbow flexor
shoulder flexor
forearm supinator
sensation on lateral forearm

Front 27

what is the main nerve continuing from the medial cord?

Back 27

ulnar nerve

Front 28

describe the passage of the ulnar nerve

Back 28

branch of medial cord
passes down medial arm towards elbow posteriorly
behind medial epicondyle of humerus
between 2 heads of flexor carpi ulnaris (supplies)
supplies medial half of flexor digitorum profundus
dorsal cutaneous branch to medial 1.5 fingers posteriorly
2 branches at hand - superficial (cutaneous) & deep - between hypothenar eminence to supply intrinsic muscles of hand

Front 29

What muscles does the ulnar nerve supply?

Back 29

flexor carpi ulnaris
medial half of flexor digitorum profundus
deep branch - intrinsic muscles of heand except thenar & lateral 2 lumbricals

Front 30

What areas does the ulnar nerve give sensation?

Back 30

dorsal cutaneous branch - medial side of hand & medial 1.5 fingers on posterior surface
superficial branch - palmar surface of 1.5 medial digits

Front 31

what muscle does the thoracodorsal nerve supply?

Back 31

latissimus dorsi

Front 32

what is the main nerve continuing from the posterior cord?

Back 32

radial nerve

Front 33

Describe the radial nerve's passage

Back 33

branch of posterior cord
behind humerus shaft in radial groove
in front of triceps - supplies 3 heads
posterior & lower lateral cutaneous branches supply skin above elbow joint
behind elbow then through brachialis & muscles arising from lateral epicondyle to enter forearm
2 branches - superficial cutaneous & deep posterior interosseous nerve

Front 34

what muscles does the radial nerve supply/

Back 34

triceps
brachialis
extensor muscles of forearm
supinator
(???)

Front 35

what areas does the radial nerve give cutaneous supply?

Back 35

lower part of arm above elbow joint - posterior & lower lateral cutaneous nerves of arm
lateral aspect of forearm posteriorly
back of hand under fingers 123

Front 36

What cords does the median nerve arise from?

Back 36

lateral & medial cords

Front 37

Describe median nerve passage

Back 37

follows axillary artery
into cubital fossa - medial to brachial artery
under pronator teres
under flexor digitorum superficialis & on top of profundus in forearm
superficial towards wrist
under flexor retinaculum at wrist & into hand
supplies lateral 2 lumbricals & thenar eminence

Front 38

What muscles does median nerve supply?

Back 38

all muscles of flexor origin (except flexor carpi ulnaris & medial half of digitorum profundus)

Front 39

What section of palm does median or ulnar nerve supply, & which is more important for sensory/motor function?

Back 39

median - lateral palm
ulnar - medial palm
median - sensory importance
ulnar - motor importance (small muscles of hand)

Front 40

If a lesion involves a root, are dermatomes or cuteneous nerve maps more important?

Back 40

dermatomes indicate areas of skin supplied by nerve roots

Front 41

Learn cutaneous nerve map of upper limb

Back 41

Front 42

Learn nerve root supply of upper limb (dermatomes)

Back 42