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2-Shoulder and Axilla


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Which muscle forms most of the anterior wall of the axilla?
pectoralis major
The pec major forms which border of the anterior axillary fold?
inferior border
Which vein runs through the deltopectoral groove?
What helps form the deltopectoral triangle?
deltoid muscle, pec major and clavicle
What is the action of the pec major?
adducts and medially rotates humerus
What innervastes the pec major?
lateral and medial pectoral nerve
What is the action of the pec minor?
fixes the scapula and stretches the arm forward to touch an object that is just out of reach, helps w/ inspiration by lifting ribs
What innervates the pec minor?
medial pectoral nerve
Discuss the function of the subclavius. Which nerve innervates it?
it has a minor function, but does give some protection to the subclavian artery, also anchors & depresses the clavicle
nerve to subclavius
What is the origination and insertion of the serratus anterior?
o-lateral surface of 1-3 ribs
i-anteromedial border of scapula
Which muscle forms the medial wall of the axilla?
serratus anterior
What is the function of the serratus anterior?
protracts the scapula-when punching or reaching anteriorly
rotates the inferior angle of the scapula so glenoid cavity is raised ie combing hair
holds scapula against thoracic wall-when doing push-ups
What nerve innervates the serratus anterior? What can result when this nerve is injured?
long thoracic nerve
paralysis of serratus anterior-winged scapula, medial border and inferior angle of scapula are pulled away from posterior thoracic wall, esp when arm is raised
cannot abduct above horizontal position (comb hair)
Which muscles are in the superficial posterior thoracoappendicular subgroup?
trapezius and latissimus dorsi
What is the action of each level of the trapezius?
superior-elevates scapula
middle-retracts scapula
inferior-depress scapula and lowers shoulder
cooperation of superior and inferior can rotate scapula
How can the trapezius be tested for injury?
have patient shrug shoulder against resistance
What innervates the trapezius? What is the result if this nerve is damaged?
cranial nerve XI (accessory)
patient cannot shrug shoulder
What is the action of the latissimus dorsi?
extends, adducts, and medially rotates humerus, brings body toward arms when climbing (monkey bars)
What innervates the latissimus dorsi? What can the patient not do if this nerve is injured? What is a common way for this nerve to be injured?
thoracodorsal nerve
can't use crutches
surgical operations
Describe the location of the triangle of auscultation and name its borders. What can be auscultated here?
Near the inferior angle of the scapula, bordered by superior border of the latissimus dorsi, inferior border of trapezius, and medial border of the scapula
listen to posterior segments of lungs
What are the muscles in the deep posterior thoracoappendicular subgroup?
levator scapulae
Discuss the location of the levator scapulae. What nerve innervates it? What is the action of this muscle?
superior third lies deep to sternocleidomstoid, inferior third is deep to trapezius
dorsal scapular nerve
assits trapezius in shrugging shoulders
What is the location of the rhomboids? What nerve innervates it?
deep to trapezius
dorsal scapular nerve
What is the result of a dorsal scapular nerve injury? How can this be tested?
scapula on affected side is further away from midline
put hands on butt facing out and flap elbows back
What muscles are in the scapulohumeral subgroup? (6)
deltoid, teres major, rotator cuff muscles
Name the rotator cuff muscles.
supraspinatus, infraspinatus, teres minor, subscapularis
Describe the muscles that help w/ abduction of the arm when the arm is initially fully adducted.
the initial 15 degrees of abduction is assisted by supraspinatus muscle, deltoid helps after that
What innervates the deltoid muscle? What can cause this nerve injury?
axillary N
shoulder joint dislocation, humeral surgical neck fx and intramuscular injection of medication
Describe how a person is able to swing their arm while walking.
the deltoid assists w/ both flexion (move anterior) and extension (posterior)
pec major assists w/ flexion, latissimus dorsi assists w/ extension
What are common appearances if the axillary N is injured?
loss of shoulder contour, hollow inferior to the acromion, loss of sensation on the lateral side of the proximal arm skin
Which border of the axilla does the teres major form?
What are the functions of the teres major?
stabilizes humeral head in socket, counteracts deltoid during abduction of the arm
What innervates the teres major?
lower subscapular N
Which nerves innervate the rotator cuff muscles?
supraspinatus & infraspinatus-suprascapular N
teres minor-axillary N
subscapularis-upper & lower subscapular N
Which of the rotator cuff muscles inserts at the lesser tubercle? Where do the others insert?
greater tubercle
Which of the rotator cuff muscles assists the deltoid in abducting the arm?
Which of the rotator cuff muscles adduct the arm? Which one assists?
subscapularis, teres minor assists
Which of the rotator cuff muscles medially rotates the arm? Laterally?
subscapularis and teres minor
infraspinatus and teres minor
Which of the rotator cuff muscles forms part of the posterior wall of the axilla?
What is often the cause of a fracture/dislocation of the proximal humeral epiphysis?
when arm or shoulder is directly hit by a blow
How can you test for a rotator cuff injury?
have patient lower their fully abducted arm slowly, when they reach 90 degrees the arm will suddenly drop
Name what makes up each part of the axilla.
Apex, Base, Anterior, Posterior, Medial and Lateral.
Apex-entrance from neck to axilla
Base-skin, subcutaneous tissue, axillary fascia
anterior-pec major&minor
posterior-scapula, subscapularis, teres major, latissimus dorsi
medial-thoracic wall (ribs 1-4), serratus anterior
The axillary artery is a continuation of which artery? When does the name change? When does it end? What name does it change to?
-when it passes the lateral border of the 1st rib
-ends at inferior border of teres major
-brachial artery
Describe the three parts of the axillary artery marked by the pec minor.
first-between lateral border of 1st rib and medial border of pect minor, enclosed in axillary sheath
second-posterior to pec minor
third-between lateral border of pec minor and inferior border of teres major
What are the branches of the axiallry artery?
first-superior thoracic
second-thoracoacromial and lateral thoracic
third-subscapular, anterior circumflex humeral, posterior circumflex humeral
Describe the superior thoracic artery and what it supplies.
small vessel, supplies muscles in 1st and 2nd rib intercostal spaces and serratus anterior
Describe the thoracoacromial artery and where it is located.
-short wide trunk, deep to clavicular head of pec minor
Which branches does the thoracoacromial artery give off?
acromial, deltoid, pectoral, clavicular
What does the lateral thoracic artery supply?
pec muscles, axillary lymph nodes and breast
What is the largest branch of the axillary artery? What does it supply? What does it divide into?
subscapular artery
supplies subscapularis, teres major, serratus anterior and latissimus dorsi
circumflex scapular artery and thoracodorsal artery
Which of the branches of the subscapular artery is larger? What does it supply?
circumflex scapular artery-supplies muscles in dorsal side of scapula
What does the thoracodorsal artery supply? What does it branch from?
supplies muscles in inferior angle of the scapula esp latissimus dorsi
branches from subscapular
What do the circumflex humeral arteries supply?
shoulder muscles ie deltoid, teres major and minor, and long head of triceps
What are the 2 compression areas of the axillary artery?
-third part of the artery-palpate inferior part of lateral wall of axilla against humerus
-at beginning of artery-downward pressure in angle between clavicle and attachment of sternocleidomastoid muscle aginst 1st rib
Why are anastomoses important in the area surrounding the shoulder region?
allow collateral circulation in case axillary artery is narrowed or ligated
At what spot can ligation stop blood supply to the arm w/o collateral circulation establishment?
distal to subscapular artery and proximal to deep artery
Where can an aneurysm of the axillary artery occur? What can it cause? Who is it likely to occur in?
-first part of artery
-may compress brachial plexus, causes pain
-baseball pitchers
Where is the axillary vein located w/ regards to the axillary artery?
anterior and medial
Where does the axillary vein begin and end? (what does it form from and merge into)
begins at inferior border of teres major by union of brachial vein and basilic vein, ends at lateral border of 1st rib and merges into subclavian vein
Does the axillary artery have more branches or does the vein have more tributaries? anastomoses? variations?
The axillary vein receives directly or indirectly from which vein?
Where does the venous blood in the superficial anterior abdominal wall drain?
above to the thoracoepigastric vein, which via axillary vein drains into superior vena cava or below to inguinal region where blood drains to IVC
Which veins are used to introduce catheters?
axillary and subclavian
What are the five principle groups of axillary lymph nodes?
apical, pectoral (anterior), subscapular (posterior), humeral (lateral), central
Where is the apical group located?
at the apex of the axilla, located on the medial side of the axillary vein
Which part of the axillary artery receives lymph from all other axillary lymph nodes? What does it empty into?
first part, empties into subclavian lmphatic trunk, which at right empties into right lymphatic duct, left empties into thoracic duct
Where is the pectoral group located? What does it collect lymph from?
-medial wall of axilla around lateral thoracic vein and inferior border of pec minor
-anterior thoracic wall including breast
What does the pectoral group empty into?
central then to apical group
Where is the subscapular group located? What does it collect lymph from?
-posterior axillary fold and subscapular vessels
-posterior thoracic wall and scapula region
Where is the humeral group located? What does it collect lymph from?
-lateral wall of axilla, medial posterior to the axillary vein
-all upper limb except lymph carried by lymphatic vessels running along the cephalic vein
Where is the central group located? What does it collect lymph from? Where does it empty?
-deep to pec minor near base of axilla
-receives lymph from pectoral subscapular, and humeral groups
-empties into apical group
Which part of the axillary artery is the central group associated with?
second part
Describe the axillary lymph node drainage.
pectoral, subscapular and humeral all drain into the central group. The central group drains to the apical group which drains to the subclavian lymphatic trunk
What can cause enlargement of the axillary nodes? Which group is the first to be affected?
infections of the upper limb or cancer of the shoulder and thoracic region
humeral group
Enlargement of which lymph node group can cause obstruction to the cephalic vein?
apical group
Which 2 nerves ar vulnerable during dissection of the axillary lymph nodes?
long thoracic nerver
thoracodorsal nerve
What forms the brachial plexus? Where does it begin and end?
union of the ventral rami of C5,6,7,8 and T1
begins in the neck and extends into axilla
What are the 3 components of the brachial plexus?
motor and sensory neurons and ANS (sympathetic) neurons
What are the five sections of the brachial plexus?
roots, trunks, divisions, cords and terminal branches (peripheral nerves)
What are the three branches in the roots? Which ventral rami make up each? What does each innervate?
dorsal scapular nerve (C5)-rhomboid and occasisonally levator scapulae
long thoracic nerve (C5,6,7)-serratus anterior
phrenic N-(C3,4,5)-diaphram
Name the 3 trunks and what each forms from.
superior-from union C5&6
middle-continuation of C7
inferior-from union of C8&T1
What branches from the superior trunk? What does each nerve innervate?
nerve to subclavius (C5&6)-subclavius
suprascapular N (C4,5,6)-supraspinatus, infraspinatus and glenoid joint
What forms the divisions of the brachial plexus? Where is this section located?
each trunk divides (no branching) into anterior and posterior divisions=6 bundles
located junst posterior to clavicle
What do the anterior and posterior divisions innervate?
anterior-muscles in anterior region of upper limb (flexors)
posterior-posterior region of upper limb (extensors)
Name the cords in the brachial plexus. What does each form from?
lateral-union of anterior division of superior and middle trunks (C5,6,7)
posterior-posterior divisions of all 3 trunks (C5-T1)
medial-continuation of anterior division of inferior trunk (C8-T1)
Name the 3 branches of the lateral cord and what each innervates.
lateral pectoral N (C5,6,7)-pec major and minor
musculocutaneous N (C5,6,7)-coracobrachialis, biceps brachii, brachialis and lateral cutaneous region of forearm
median N-flexor muscles of anterior compartment of forearm, 5 muscles in hand, skin of part of hand
Name the 5 branches of the medial cord and what each innervates.
medial pectoral (C8, T1)-pec major and minor
medial cutaneous nerve of arm and forearm (C8, T1)-skin on medial side
ulnar (C8, T1)-flexor carpi ulnaris and flexor digitorum profundus, medial side of hand
medain N-
Name the 5 branches of the posterior cord and what each innervates.
upper subscapular (C5,6)-subscapularis
thoracodorsal (C6,7)-latissimus dorsi
lower subscapular (C6,7)-teres major and inferior part of subscapularis
axillary (C5,6)-teres minor, deltoid
redial (C5,6,7,8,T1)-extensor muscles of posterior compartment of upper limb, skin of posterior arm and forearm
What does the axillary nerve become? What will it supply?
superior lateral cutaneous nerve, supplying skin over inferior half of deltoid
What is the largest branch of the brachial plexus?
What nerve can be injured during humeral fracture b/c of its groove along the humerus?
What is meant by a prefixed brachial plexus? postfixed?
plexus forms from C4-8 instead of C5-T1
What can happen in a postfixed brachial plexus?
inferior trunk of plexus may be compressed by 1st rib, producing neurovascular symptoms in upper limb
What can cause injury to the superior (C5,6) part of the brachial plexus?
excessive separation of head and neck such as falling w/ shoulder on ground or excessive stretching during baby delivery
What is the characteristic appearance of a person w/ superior injury to the brachial plexus (Erb palsy, Erb-Cuchenne palsy, upper radicular syndrom)?
waiter's tip position, injured limb hangs by side in medial rotation
In a superior injury to the brachial plexus what part of the body loses sensation? Which muscles are paralyzed?
lateral aspect of upper limb
deltoid, biceps, brachialis, and brachioradialis
Describe Backppacker's palsy. What nerves are involved?
micro injury of superior trunk of brachial plexus, sensory deficits in distribution of musculocutaneous and radial nerve, may produce muscle spasms
What can cause compression of the cords of the brachial plexus? What are the effects?
hyperabduction of the arm (painting a ceiling)
pain running down arm, numbness, tingling and erythema
What can cause an injury to the inferior part (C8, T1) of the brachial plexus? Which muscles are affected and what is the characteristic appearance?
sudden pull of the arm superiorly (grasping a tree branch to stop a fall)
short muscles of hand are affected = clawhand
Which nerve is affected w/ clawhand? Which fingers can't flex?
ulnar N
pinkie and ring finger
Where is a local anesthetic administed when doing a brachial plexus block? What structures must be avoided? What gets blocked?
angle between the posterior border of sternocleidomastoid and clavicle, into the axillary sheath containing the cords
don't inject into vessels and watch lungs
blcoks all deep structures of upper limb and skin distal to middle of arm

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