Axilla and Brachial Plexus, and Posterior Shoulder Flashcards
what are the borders of the axilla
what are 2 of the main muscles of climbing
latissimus dorsi and pectoralis major
what is the axillary vein a continuation of
brachial vein (deep vein of arm)
it becomes the axillary vein at the lower border of teres major muscle
teres major
where can pulsations of the subclavian artery be palpated
where it crosses the first rib
what are the cords of the brachial plexus named in relation to
the axillary artery
where do the roots and trunks of the brachial plexus lie
mainly between the anterior and middle scalene muscles in the root of the neck
where do the divisions of the brachial plexus lie
deep to the clavicle (posterior to subclavian vessels in root of neck)
where do the cords of the brachial plexus lie
around the axillary artery
what supplies the anterior muscles of the arm
musculocutaenous nerve
what muscle does the musculocutaenous nerve pierce on its way down to arm
coracobrachialis
where does the axillary nerve lie in relation to the radial nerve
superior
describe the path of the axillary nerve around the humerus
wraps around the posterior aspect of the surgical neck of the humerus - vulnerable to injury in shoulder dislocation or fractured neck of humerus
describe the path of the radial nerve around the humerus
wraps around posterior aspect of mid shaft of the humerus - in the radial groove
what compartment of the arm are the axillary and radial nerves in
posterior
what is the deltoid muscle innervated by
axillary nerve
function of the posterior part of deltoid
extend the shoulder
function of the middle part of deltoid
abduction at shoulder
anterior part of deltoid action
flexion of shoulder
(clavicular part)
what is the trapezius innervated by
CNXI (spinal accessory nerve)
also innervates the sternocleidomastoid
function of the trapezius
descending (superior) part - elevates scapula
middle - retracts scapula
ascending (inferior) part - depresses scapula
what parts of the trapezius produce superior rotation of glenoid fossa
ascending and descending (abduction movement)
what is the action of the levator scapulae
elevation of scapula and inferior rotation of glenoid fossa (adduction movement)
what is the action of the rhomboid muscles
retraction of scapula and inferior rotation of glenoid fossa
action of rotator cuff muscle
- supraspinatus - first 15 degrees abduction of shoulder
- infra spinatus and teres minor - external rotation
- sub scapularis - internal rotation
innervation of the rotator cuff muscles
- supra and infra spinatus - suprascapular nerve
- subscapularis - upper and lower subscapular nerve
- teres minor - axillary nerve
painful arc syndrome
impingement of supraspinatus tendon between the humerus and the acromion process can lead to this
patients typically complain of pain during 50-130 degrees of abduction
patient will tend to throw upper limb to the side to initiate abduction
elevation of scapula
descending part of trapezius
depression of scapula
gravity
and ascending trapzius etc
protraction of scapula
serratus anterior
retraction of scapula
middle part of trapezius and rhomboids
upward rotation of scapula
descending and ascending part of trapezius and serratus anterior
downward rotation of scapula
mainly latissimus dorsi
also rhomboids
what is the deltoid muscle supplied by
axillary nerve
what is the teres minor suplied by
axillary nerve
attachments of the deltoid
lateral 1/3 of clavicle
deltoid tuberosity of humerus
where does the subacromial bursa lie
between supraspinatus tendon and acromion process of scapula
inflammation may give rise to shoulder pain, especially on abduction
medially, what is the sensory innervation to the posterior aspect of the arm
anterior rami of spinal nerves C8, T1 and T2
intercostal brachial nerve, medial and posterior cutaneous nerves of arm and medial cutaneous nerve of forearm
where is a common site for referred cardiac pain
left upper limb
laterally, what is the sensory innervation to the posterior aspect of the arm
anterior rami of spinal nerves C5 and C6 via the axillary nerve
muscle in pos compartment of the arm
triceps brachii
what is the triceps brachii innervated by
radial nerve
attachments of the triceps brachii
proximal:
long head - infraglenoid tubercule of scapula
superior (lateral head) and inferior (medial head) to radial groove of humerus
distal:
all 3 heads combine to form triceps tendon, which attaches to olecranon process of the ulna
what nerve roots is the axillary nerve made up of
C5 and C6
what muscles does the axillary nerve supply
deltoid and teres minor
what is the sensory function of the axillary nerve
give rise to superior lateral cutaenous nerve of arm - innervates badge area
what is the quadrangular space
gap in muscles of posterior scapular region
the axillary nerve passes through this space
what should patients who have sustained an inferior dislocation of the shoulder joint undergo
assessment of sensation in region of badge patch to test function of axillary nerve
it can also be tested by asking patient to abduct their limb above 15 (middle deltoid)
what nerve roots make up the radial nerve
C5- T1
where is the radial nerve found in the humerus
in the radial groove
how does the radial nerve enter the forearm
through the cubital fossa
what is the radial nerve vulnerable to
mid shaft fracture of humerus
its function can be tested by testing the triceps barchii
what is the action of the superficial muscles of the posterior forearm
extension, adduction, abduction of the wrist
extension of fingers
what is the action of the deep muscles of the forearm
extension and abduction of the thumb
supination of the forearm
where do the deep muscles of the anterior forearm attach
shafts of radius and ulna and the interosseous membrane
what holds the tendons in place as they cross the wrist
extensor retinaculum
brachioradialis
- classified as posterior as supplied by radial nerve, but located in boundary between anterior and posterior compartments
- main action is flexion of semi-pronated arm
- eg when drinking from cup
where does the radial nerve split into superficial and deep branch
anterior to lateral epicondyle (cubital fossa)
describe the course of the deep branch of radial nerve
passes into pos compartment of the forearm by winding around the neck of radius and passing through supinator muscle, which it supplies
now renamed posterior interosseous nerve
what are the muscles in the anterior compartment of the arm supplied by
musculocutaneous nerve
what do muscles does the spinal accessory nerve supply
sternocleidomastoid and trapezius
what muscles act to externally rotate the shoulder
supra and infraspinatus and teres minor
what muscles act to internally rotate the shoulder
sub scapularis
action of the triceps brachii
weak extension of the arm at shoulder joint
extension of the forearm at elbow joint
what are the attachments of the biceps brachii
proximally: long head to supraglenoid tubercule of scapula and short head to coracoid process of scapula
distally: biceps tendon to radial tuberosity
bicipital aponeurosis blends into deep (antebrachial fascia) on the medial side of proximal forearm
what are the 3 muscles that attach to the coracoid process
pec minor
CORACObrachialis
short head of biceps
path of long head of biceps brachii
passes superiorly in the intertubercular groove of humerus and then becomes enclosed within the fibrous layer of the shoulder joint capsule to reach the supraglenoid tubercule of scapula
what can cause biceps tendinitis
movement of the long head of biceps in the intertubercular groove
causes shoulder pain that is reproduced on direct palpation of the tendon
what nerve roots is musculocutaneous nerve made up of
C5, 6, 7
what does a positive biceps deep tenon (myotactic) reflex confirm
- function of muscle, musculocutaneous nerve, central connections at spinal cord level and above
- C5 and 6
how is a biceps deep tendon reflex elicited
placing thumb on biceps tendon in cubital fossa and striking thumb with a hammer
muscle should involuntarily contract - flexion of forearm at elbow
attachments of the coracobrachialis
coracoid process
humerus
coracobrachialis
how is the coracobrachialis separated from the triceps
medial intermuscular septum
attachments of brachialis
humerus
coronoid process of ulna
how is the brachialis separated from the triceps
lateral intermuscular septae
biceps brachii action
powerful supinator and flexor (supination is most powerful in flexion)
innervation of the muscles of the forearm anterior
median nerve
except flexor carpi ulnaris and medial half of flexor digitorum profundus - ulnar nerve
superficial muscles of anterior forearm from lat to medial
where does the palmaris longus attach to distally
palmar aponeurosis
where do the flexor carpi ulnaris and radialis attach distally
metacarpals on ulnar and radial side, respectively
where do the superficial muscles of ant compartment of the forearm attach proximally
via common flexor tendon to medial epicondyle of the humerus
flexor digitorum superficialis
where does the FDS attach
proximally to distal humerus, coronoid process of ulna and radial head
what is the palmar aponeurosis
thickened central area of palmar fascia
usually continuation of palmaris longus (superficial layer anterior compartment)
proximal attachment of FPL
shaft of radius and ulna and interosseous membrane
proximal attachment of PQ
distal anterior surfaces of radius and ulna
where does teh common flexor tendon attach
medial epicondyle of humerus (superficial anterior muscles of forearm)
what is pain in the medial epicondyle of the humerus referred to as
golfers elbow
can be a result of tendonitis of the flexor tendon
what are the borders of the cubital fossa
what is the superficial contents of the cubital fossa
median cubital vein, cephalic vein, basilic vein
what is the deep contents of the cubital fossa
distal tendon and aponeurosis of the biceps brachii
median nerve, brachial artery and radial nerve
describe the location of the cephalic and basilic veins and how they communicate
median cubital vein
what does the brachial artery do at the apex of the cubital fossa
bifurcate into radial and ulnar arteries
where is the ulnar nerve found and readily injured
posterior surface of the medial epicondyle of the humerus - funny bone site
passes through the flexor carpi ulnaris to reach the anterior compartment of the forearm
how is the shoulder joint stabilised (static)
labrum and joint capsule
bankart lesion
injury of anterior (inferior) glenoid labrum of the shoulder due to anterior disocation of the humerus
adhesive capsulitis
eg frozen shoulder
capsule of joint necomes really tight - restricts motion (particularly external rotation) and causes chronic pain
wrist drop
cant extend arm due to injury to the radial nerve (supplies all the extensor muscles (posterior) in the upper limb)
where is radial nerve susceptible to injuries
humeral shaft fractures
where do the extensors(posterior) of the forearm attach
lateral epicondyle
where do the flexors (anterior) of the forearm attach
medial epicondyle
tennis elbow
lateral epincondylitis
how does tennis elbow occur
repetitive strain injury in tennis players and those who often perform resisted extension at the wrist
can also be a degenerative enthesopathy
same for golf elbow
pathology of tennis elbow
micro tears in the common extensor origin
golf elbow
medial epicondylitis
what risk does injection into the area of golf elbow carry
injury to ulnar nerve
what joints in the arm facilitate supination and pronation
proximal and distal radio-ulnar (pivot type joints)
monteggia fracture
high energy fracture
mid shaft of ulna
galeazzi fracture dislocation
fracture of radius and dislocation of ulna
triceps jerk
C6-7, radial nerve
what fracture is notoriously difficult to spot on x ray and has a risk of AVN
scaphoid fracture (falling on outstretched hand)
risk of AVN due to retrograde blood supply
duputyrens contracture
thickening of the palmar fascia
cant be gotten rid of
trigger finger
fingers catch or lock when bent
happens when tendons become inflamed
how does one test the function of the median nerve
how does one test the adductor pollicus
froment’s test
describe the dermatomal distribution of the arm
- C6 - make a 6 with thumb and finger
- C8 - pinkie
describe the sensory supply of the arm
supraspinatus
infraspinatus
teres minor
teres major
brachioradialis reflex
C5-6, radial nerve
