Brachial plexus Flashcards by 1994tso .

the brachial plexus contains nerve roots from where

anterior (ventral) rami of C5-T1

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axillary nerve is what roots

C5 C6

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what would the implication of damaged C5 be in terms of the axillary nerve and deltoid

C6 fibres would still allow some innervation of deltoid - abduction of arm would be weaker but still possible

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the brachial plexus is found where

in the axilla

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the brachial plexus originates where

nerves originate from C5-T1 nerve roots in the neck and upper thorax (for T1)

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where do the brachial plexus nerve roots lie

posterior triangle of neck

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the brachial plexus nerve roots pass between what muscles

anterior and middle scalene

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what innervation do the nerve roots of the brachial plexus receive

grey rami communicantes so carry post-ganglionic sympathetic fibres

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what forms the superior trunk

C5 and C6

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what forms the middle trunk

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what forms the inferior trunk

C8 and T1

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the trunks of the brachial plexus pass where

over rib 1 and enter axilla

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what makes up the phrenic nerve

C3 and C4 fibres from above the brachial plexus but also includes C5 fibres from C5 root

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what other nerve gets its C5 component directly from this root

dorsal scapular nerve

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what is the long thoracic nerve derived from

directly from C5 6 7 roots

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what trunks give rise to nerves

middle and inferior do not, superior does

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what nerves does the superior trunk form

suprascapular nerve
nerve to subclavius

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the phrenic nerve innervates what

diaphragm

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the dorsal scapular nerve innervates what

rhomboid major and minor

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long thoracic nerve innervates what

serratus anterior

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suprascapular nerve supplies

infraspinatus and supraspinatus

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suprascapular nerve and nerve to subclavius roots

C5 6

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nerve to subclavius innervates what

subclavius muscle

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each trunk divides into an anterior and posterior ____ as they enter the axilla

division

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all of the posterior divisions form the

posterior cord

the anterior division from the superior and middle trunks forms what

lateral cord

anterior division from inferior trunk forms

medial cord

what forms the posterior cord

all the posterior divisions of the trunks

what forms the lateral cord

anterior division of superior and middle trunk

what forms the medial cord

anterior division of inferior trunk

are there any peripheral nerves direct from the divisions

the 3 posterior divisions are the ultimate pathway for what

nerves assoc. with the posterior compartments of the arm and forearm

the 3 anterior divisions are the ultimate pathway for what

nerves assoc. with anterior compartments of the arm and forearm

what nerves will the anterior divisions form

musculocutaneous median and ulnar nerves

what nerves will the posterior divisions form

radial nerve and axillary nerve

what is the nerve of the posterior compartment of the arm and forearm

radial nerve

the cords are named dependent on what

relation to the axillary artery

which cord lies closer to the humerus

lateral cord

what cord lies closer to the body wall

medial cord

what cord lies behind the axillary artery

posterior cord

the lateral cord has what fibres

C5 - C7

the lateral cord originates from what

anterior divisions of the superior and middle trunks

lateral cord is origin of what nerve

lateral pectoral nerve

the posterior cord originates from what

posterior divisions from all trunks

the posterior cord has what fibres

C5-T1

the posterior cord is the origin of what nerves

subscapular and thoracodorsal

the medial cord is formed from what

continuation of anterior division of inferior trunk

medial cord has what fibres

C8 T1

how does the medial cord get C7 fibres

often communication with middle trunk or its divisions which allows some C7 fibres in its terminal branches - some texts will say ulnar nerve has (C7) C8 T1 fibres meaning minor contribution from C7 root

is it common to see non-standard patterns of the nerves of the brachial plexus

yes especially for lateral cord and median nerve

anterior compartments of arm and forearm supplied by what cords

medial and lateral cords

posterior compartments of arm and forearm supplied by what cords

posterior cord

the medial cord is the origin of what nerves

medial pectoral and cutaneous nerves

all of the cords of the brachial plexus form branches and terminal branches where

branches in the axilla and terminal branches as they exit the axilla

what does the lateral cord form

lateral pectoral nerve before it forms the musculocutaneous nerve and the lateral part of the median nerve

the lateral pectoral nerve supplies what

pec major

the musculocutaneous nerve supplies what

anterior compartment of arm

the median nerve supplies what

main nerve of anterior compartment of forearm

the posterior cord forms what

subscapular nerves and thoracodorsal nerve before forming terminal branches of axillary nerve and radial nerve

subscapular nerves supply what

subscapularis and teres major

thoracodorsal nerve supplies what

latissimus dorsi

axillary nerve supplies what

deltoid and teres minor

radial nerve supplies what

posterior compartment of arm and forearm

the medial cord forms what

medial pectoral nerve and 2 cutaneous nerves to the arm and forearm before ending in the ulnar nerve and medial root of the median nerve

the medial pectoral nerve supplies what

pec major and minor

ulnar nerve supplies what

anterior compartment of forearm and many intrinsic muscles of the hand

what nerve supplies anterior compartment of the arm

musculocutaneous nerve

what nerve supplies the posterior compartment of the arm

radial nerve

what nerve supplies the posterior compartment of the forearm

radial nerve

what nerve supplies the anterior compartment of the forearm

mainly median nerve but also ulnar nerve

each terminal branch also carries ____ fibres

sensory

the axillary nerve supplies motor and sensory to what

motor - deltoid and teres minor sensory - skin of upper lateral arm (badge patch area)

what nerve goes from the lateral cord and disappears into the coracobrachialis

musculocutaneous nerve

how can you identify the median nerve

forms from the lateral and medial cords in the M shape

what is the course of the median nerve

descends the anterior compartment of the arm to pass through cubital fossa and later also carpal tunnel at the wrist to pass into the hand

the ulnar nerve lies _____ in arm

medially

describe the course of the ulnar nerve

lies medially in the arm before passing behind the medial epicondyle of the humerus to lie in medial side of forearm and then pass into hand

how can the posterior cord be identified

lies behind the axillary artery and forms terminal branches deep to the M shape

what nerve wraps around the neck of the humerus

axillary nerve

describe the course of the axillary nerve

wraps around neck of the humerus to pass through the quadrangular space to enter deltoid and teres minor

when might axillary nerve be damaged

antero-inferior dislocation of glenohumeral joint as it lies close to the joint

describe the course of the radial nerve

passes deep in the arm before leaving the anterior surface of the humerus and passing through the triangular hiatus to reach posterior compartment of arm. It then travels at the lateral side of the cubital fossa to reach the posterior compartment of forearm

what nerve passes through the quadrangular space

axillary nerve

what nerve passes through the triangular hiatus

radial nerve

anterior compartments of the arm and forearm are often called

flexor compartments

posterior compartments of the arm and forearm are often called

extensor compartments

how is the spiral groove created

radial nerve courses around the humerus in the arm creating the spiral groove

what attaches either side of the spiral groove

lateral and medial heads of the triceps brachii attach to humerus either side of spiral groove

how can radial nerve be damaged

mid-shaft fracture of humerus as it is close to the bone here

musculocutaneous nerve fibres

C5-7

axillary nerve fibres

C5 C6

radial nerve fibres

C5-T1

median nerve fibres

lateral root: C6,C7 medial root: C8,T1

ulnar nerve fibres

C8 T1 (often C7)

the lateral root of the median nerve is a terminal branch of what

lateral cord (C6 7)

the medial root of the median nerve is a terminal branch of what

medial cord (C8 T1)