Brachial Plexus and Pectoral

Question 1

3 main transition zones in upper limb

Answer 1

axilla- armpit

cubital fossa- depression anterior to elbow

carpal tunnel- flexor tendons and median nerve gateway to wrist

Question 2

fn of clavicle

Answer 2

moveable strut allowing scapula to move

helps transmit shock from upper limb to axial skeleton

Question 3

most common fracture

Answer 3

clavicle- usually through middle third of bone

shoulder falls lower than other side, pts hold and support arm

Question 4

subclavian muscle

Answer 4

lays under clavicle, protects brachial plexus and other structures under clavicle

Question 5

SC joint

Answer 5

synovial joint b/w clavicle and manubrium- only articulation b/w upper limb and axial skeleton

very strong articulation w/ rare dislocation, but have around 60 degree ROM

Question 6

SC dislocaitons

Answer 6

can be an emergency, heart and trachea lie behind the joint

Question 7

SC ligaments

Answer 7

anterior and posterior SC ligaments

interclavicular ligement along superior aspect of both joints

intra articular fiborcartilagenous disc acts as shock absorber (helps w/ FOOSH)

Question 8

AC joint

Answer 8

synovial joint b/w acromion and clavicle, surrounded by loose fibrous capsule

Question 9

AC ligaments

Answer 9

AC ligament- superior strength to capsue

coracoclavicular ligaments (trapezoid and conoid ligaments)- provides main strength

coracoacromial ligament- arch, bw/ coracoid and acromion processes

Question 10

contrast 3 degrees of AC injuries

Answer 10

first- stretch or minor tear of AC ligament, still intact

second- subluxation, not totally separate

third- both AC and coracoclavicular ligaments torn, shoulder separation (essentially similar to broken clavicle)

Question 11

insertion of pec major

Answer 11

lateral lip of intertubercular sulcus or bicipital groove

Question 12

fn of pec major

Answer 12

internal rotation and adduction and flexor of arm

Question 13

innervation of pec major

Answer 13

medial and lateral pec nerves

Question 14

pec minor

Answer 14

inserts coracoid process

stabilizes scapula against thoracic wall

innervated by medial pec nerve

Question 15

pec minor “bridge”

Answer 15

arches over axillary artery, axillary vein, brachial plexus

Question 16

axillary artery progression

Answer 16

from subclavian as passes first rib, then 3 parts by pec minor as axillary, then brachial artery as passes lateral to teres major

Question 17

2 key branches of axillary

Answer 17

subscapular- largest branch, anastamoses around scapula

anterior and posteriorr humeral circumflex- vascularize humerus and surrounding msucles

Question 18

key role of suprascapular artery

Answer 18

can provide collateral circulation if axillary artery is thrombosed

Question 19

5 segments of brachial plexus

Answer 19

roots
trunks
divisions
cords
 branches

Question 20

BP roots

Answer 20

formed by ventral rami of C5 thru T1

Question 21

formation of BP trunks

Answer 21

C5 and C6 form superior trunk

C7 is middle trunk

C8 and T1 form inferior trunk

Question 22

formation of BP divisions

Answer 22

each trunk forms anterior and posterior divisions

anterior forms nerves that innervate anterior compartments, posterior form posterior nerves

Question 23

formation of BP cords

Answer 23

anterior divisions of superior and middle trunk form lateral cord

anterior division of inferior trunk is medial cord

posterior of all three form posterior cord

Question 24

formation of BP terminal branches

Answer 24

lateral cord rise to musculocutaneous and lateral root of median nerve

posteriror cord gives rise to radial and axillary nerves

medial cord gives rise to ulnar nerve and medial root of median nerve

Question 25

innervation of 5 terminal branches of BP

Answer 25

musculocutaneous- flexors of arm ulnar- intrinsic muscles of hand and some forearm flexors axillary- deltoid and teres minor radial- extensors of arm and forearm median- most forearm flexors and thenar (thumb) muscles

Question 26

spinal nerve origins for each BP terminal branch

Answer 26

musculocutaneous- C5,6,7 axillary- C5,6 radial- C5,6,7,8, T1 median- C5,6,7,8 T1 ulnar- C8, T1 (sometimes C7)

Question 27

muscles that BP and subclavian must pass thru

Answer 27

anterior and middle scalene, prevertebral fascia surrounds these muscles

Question 28

axillary sheath

Answer 28

extension of prevertebral fascia extending laterally, surrounds BP and axillary artery

Question 29

names of BP cords depend on

Answer 29

location relative to axillary artery- ie lateral cord is lateral to axillary artery

Question 30

exception to BP innervation in upper limb

Answer 30

intercostobrachial nerve- lateral cutaneous sensory nerve, branch of T2 intercostal nerve supplies region of skin along medial aspect of arm not affected by BP nerve block

Question 31

components of BP below clavicle

Answer 31

cords and terminal branches, everything else is cranial

Question 32

sensory info from dermatomes to spinal cord enter..

Answer 32

via dorsal root, cell bodies in DRG

Question 33

site of dormancy of VZV

Answer 33

DRG of certain spinal nerves, reactivate along dermatomes, usually unilateral

Question 34

key dermatomes for MSK

Answer 34

``` C5- tip of shoulder C6- thumb C7- middle finger C8- little finger T1- medial arm ```

Question 35

8 branches of BP

Answer 35

``` long thoracic dorsal scapular suprascapular upper subscapular middle subscapular lower subscapular medial and lateral pectoral medial cutaneous nerves (arm and forearm) ```

Question 36

long thoracic

Answer 36

from C5,7 serratus anterior

Question 37

dorsal scapular

Answer 37

C5, rhomboids and levator scapula

Question 38

suprascapular

Answer 38

C5,6 supra and infraspinatus

Question 39

upper subscapular

Answer 39

C5,6 | subscapularis

Question 40

middle subscapular

Answer 40

C6,7,8 | latissimus dorsi

Question 41

lower subscapular

Answer 41

C5,6 | teres major and subscapularis

Question 42

medial and lateral pectoral

Answer 42

medial C8, T1 lateral C5,6,7 pectoral muscles

Question 43

medial cutaneous nerves of arm and forearm

Answer 43

C8, T1 sensation to medial arm and forearm