Shoulder and Brachial Plexus Anatomy Flashcards
what movements can the shoulder perform?
-flexion and extension
-abduction/adduction
-interal/external rotation
-circumduction
what movements can the elbow perform?
-flexion/extension
-pronation and supination
what movements can the wrist perform?
-flexion/extension
-abduction/adduction
what is circumduction?
circular movement a ball and socket joint
what is pronation/supination?
rotating the forearm
-moves palm from ant to post facing or vice versa
-not medial rotation, requires arm to be Half flexed
what is aposition?
gripping between fingers and thumb
-reposition = release
-opposition of thumb = only when thumb meets 5th digit
what are the possible movements of digits?
-flex
-extend
-abduct
-adduct
-circumduct
what is the pectoral girdle?
the scapula and humerus working around the shoulder
what is the shoulder joint?
glenohumeral joint
where is the clavicle located?
from the manubrium to the acromion
sits just above humerus
what classifies the clavicle?
-has slight sigmoid curves
-conccave lat convex med
-has space for vessels and nerves
-transmits weight
-acts as strut (holds limb out and transfers weight)
-strong ligaments of SC joint (bone is more likely to break rather than muscles or tendons)
what is the scapula?
-large flat triangular bone
what ribs does the scapula overlap?
2-7
what is the spine of the scapula?
the sharp ridge that goes laterally across, supraspinous fossa and infraspinous fossa
what is the acromion process?
lateral, high point of the shoulder, articulates with the clavicle
what is the coracoid process?
lateral & anterior, where muscles attach
what is the glenoid cavity?
laterally, inferior to acromion, articulates with humerus
where does the scapula have a joint connection to the axial skeleton?
it does not.
which muscles hold the scapula in place?
-trapezius
-levator scapulae
-rhomboid major and minor
-serratus anterior
-pectoralis minor
what happens when the scapula moves?
moves around AC and SC joints, generated by muscles that attach scapula to trunk
-indirectly also muscles trunk to humerus when shoulder fixed
what is protraction/retraction?
pushing and retracting
what happens when there is a lateral rotation/abduction of the scapula?
tilts the glenoid cavity upwards
what happens when there is a medial rotation/ adduction of the scapula?
brings arm back down
what is the floor of the axilla?
upward arching sheet skin
what is the apex of the axilla?
points up and medially, continuous with neck root
what is the anterior wall of the axilla?
pectoral muscles
what is the posterior wall of the axilla?
subscapularis, tires major and lat dorsi
what is the medial wall of the axilla?
chest wall and serrates ant
what is the lateral wall of the axilla?
the humerus and muscles
what is the pectoralis major?
fan shaped superficial muscle
what are the attachments of the pectoralis major?
has 2 heads
-medial clavicle
-sternum and upper 6 costal cartilages, aponeurosis of external obliques
-humerus (crest of greater tubercle & lat lip of inter tubercle groove
lower fibres trust to form U shaped tendon
what are the actions of the pectoralis major?
both heads together
-protracts and depresses scapula
-adducts & medial rotation humerus
-clav head - flexes humerus
-sternocostal - extends humerus
what nerve innervates pectoralis major?
medial and lateral pectoral nerves
what is the pectoralis minor?
a triangular muscle, deep to major
what are the attatchments of the pectoralis minor?
3-5th ribs
coracoid process of scapula
what are the actions of the pectoralis minor?
-depresses shoulder
-pulls scapula (&shoulder) forward
-raises ribs (inspiration) when scapula fixed
what nerve innervates the pectoralis minor?
medial pectoral nerve
what is the brachial plexus?
nerve supply to the upper limb
what makes up the brachial plexus?
ventral rami of nerves from C5-T1 spinal nerve roots
has some minor contributions from C4 and T2
extends inferiorally and lateral through the neck/axilla and into arm
what does the brachial plexus do?
provides sensory, motor and sympathetic nerve supply to the pectoral girdle and upper limb except for trapezius.
the complex re-routing gives back up mechanism
what comes off from the lateral cord?
musculo cutaneous nerve and the axillary nerve
what comes off the posterior cord?
axillary nerve and radial nerve
what makes up the median cord?
fibres from the lateral and medial cord
where does the ulnar nerve come off?
medial cord
what are the roots of the brachial plexus?
5 of them, vetral rami of C5-T1 spinal nerves, unite in a pattern to form 3 trunks
-emerge between scalene anterior and medius muscles
what are the trunks of the brachial plexus?
3 of them, each trunk divides to give an anterior and posterior division
located within the neck
what are the divisions of the brachial plexus?
6 of them, regroup and restructure to give cords
-pass deep to middle 1/3 of clavicle
-into apex of axilla and regroup to form cords
what are the cords of the brachial plexus?
3 of these, give rise to 5 terminal branches
-lie posteriorly to axillary artery
what do the anterior divisions of the brachial plexus do?
supply FLEXOR muscles &skin on FRONT OF UL
what do the posterior divisions of the brachial plexus supply?
EXTENSORS and skin on BACK of UL
where does the brachial plexus end?
lower border pectoralis minor by dividing into nerves
what does the lateral cord consist of?
-musculocutaneous nerve, pierces coracobrachialis muscle
-supplies it, biceps brachia and brachialis
-lateral root of median nerve supplies forearm flexors & thenar eminence
-continues as lateral cut of forearm
what makes up the medial chord?
-medial root of median nerve, forearm flexors and thenar eminence
-ulnar nerve intrinsic muscles of the hand
-also continues as 3 sensory cutaneous nerves
what comes from the posterior cord?
-radial nerve, largest and innervates all extensor muscles in arm and forearm
-axillary nerve - innervates teres minor and deltoid
what are the main supraclavicular branches?
dorsal scapular
long thoracic
supra scapular
where is the dorsal scapular?
from ramus of C5, supplies rhomboids
where is the long thoracic nerve?
from the ventral rami of C5-C7, supplies serratus anterior
where is the supra scapular nerve?
from the superior trunk, supplies suprasinatus & infraspinatus
what are the main infraclavicular branches of the brachius plexus?
-medial and lateral pectoral
-upper and lower subscapular
-thoracodorsal
where do the upper and lower sub scapular nerves come from?
come from posterior cord, sub scapular and tires major
where does the thoracodorsal nerve come from?
lattismus dorsi
what is crutch palsy?
prolonged use of crutches, compression to radial nerve, affects extensor muscles
what happens when there is damage to the radial nerve?
drop wrist, can’t extend hand it is caused by intramuscular injections into the deltoid and hits radial nerve
what is carpal tunnel syndrome?
median nerve damage
compression of the nerve
can cause numbness, tingling and pain in palm and fingers
caused by repetitive wrist flexion
where is the axillary nerve?
comes from the posterior cord C5-C6
what muscles does the axillary nerve innervate?
teres minor - laterally rotates arm
deltoid - abducts arm
(cutaneous (sensory) innervation to inferior lateral shoulder)
where is the ulnar nerve?
comes off the medial cord, C8-T1
what does the ulnar nerve do?
-flex and adduct wrist
-flex fingers
-adducts thumb
-controls hypothenar muscles
-flexes metocarpalphalangeal joints and extends interphalangeal joints
-abducts and adducts fingers
where is the median nerve?
comes from the median and lateral cords, C5-T1
what does the medial nerve do?
-pronates forearm and hand
-flexes and abducts wrist
-flexes fingers
-controls thumb muscle
controls thenar muscle
-flexes metacarpophalangeal joints and extends interphalangeal joints
what are the joints of the pectoral girdle?
sternoclavicular joint
acromioclavicular joint
what is the sternoclavicular joint?
-notch of manubrium and medial clavicle
-acts like ball and socket
-accompanies scapula joint
-highly strengthened by ligaments
-synovial joint
why is the sternoclavicular joint so strong?
-caspule thickened ant and post by sternoclavicular ligaments
-intraclavicular ligament - med end of clavicle, connects them along the middle
-joint extends superiorly to 1st costal cartilage
-costoclavicular ligament strengthens inferior aspect of this joint.
what is the acromioclavicular joint/
-from the lateral clavicle to the acromion process
-sliding synovial joint
what strenghtens the AC joint?
ligaments
-coracoclavicular
-acromioclavicular
-corocoacromial
what kind of joint is the gelnohumeral joint?
synovial multiracial ball and socket joint
limited stability due to poor bony fit and loose capsule and ligaments
what stabilises the glenohumeral joint?
the rotator cuff muscles
where does the radius articulate with the humerus?
the capitulum
where does the ulna articulate with the humerus?
trochlea
where does the synovial capsule of the glenohumeral joint attatch?
proximally
-scapula beyond supraglenoid tubercle
-margin of labrum
distally
-anatomical neck of humerus
what are bursae?
fluid filled sac lined by synovial membrane
-found around most major joints
-reduce friction
what muscles help flex the arm?
pectoralis major
anterior fibres of deltoid
assisted by short head of biceps and coracobrachialis
what are the bursae of the glenohumeral joint?
-subacromial
-subscapular
-subdeltoid
-subcoracoid bursae
what muscles would be involved in extension of the arm?
from anatomical position
-posterior fibres of deltoid and lat dorsi
extension to return to anatomical position
-lat dorsi, tires major, pectoralis major
what muscles control abduction of arm?
first 15-30 bu supraspinatous
after it is deltoid
over head requires lat rotation of scapula (serious anterior and trap)
what muscles control adduction of arm?
lat dorsi and lowers sternocostal fibres of pectoralis major
what muscles control medial rotation of the arm?
TRUNK TO ANT HUMERUS
pectoralis major
lat dorsi
SCAPULA TO ANT HUMERUS
subscapularis
teres major
what muscles are involved in the lateral rotation of the arm?
infraspinatus
deltoid
teres minor
what muscles attach some distance from the shoulder?
(considerable mechanical effect on shoulder)
deltoid
terms major
short head biceps Brachi
which muscles lie close to the shoulder?
(smaller mechanical effect on shoulder)
-stabilise joint
-act as main ligaments
long head biceps
-triceps brachii
-rotator cuff
what are the rotator cuff muscles?
-supraspinatus
-infraspinatus
-teres minor
-subscapularis
what do the rotator cuff muscles do?
contract together, major stabilising force shoulder
contract individually to cause movement
join scapula to humerus
what does the infraspinatus muscle do?
-scapula -post/sup greater tubercle humerus
-lat rotation and stabilisiation
-innervated by subscapular nerve
what does teres minor do?
-scapula (lat margin)- post greater tubercle humerus
-lateral rotation and stabilisation
-innervated by axillary nerve
what is the supraspinatus muscle?
-from scapula to sup greater tubercle humerus
-abduction and stabilisation
-innervated by supra scapular nerve
what is the subscapularis muscle?
-from scapula to lesser tubercle humerus
-medial rotation and stabilisation
-innervated by subscapular nerve
what is dislocation?
most frequently in shoulder
humeral head pushes against weakest part of capsule
tears ligaments and articular capsules
what are rotator cuff injuries?
common if limb was above head
tear supraspinous tendon
frozen shoulder
what is the axillary nerve injury?
may be injured with dislocations by the head of the humerus
-paralysis of deltoid and loss of sensation in small area of skin over deltoid
which muscle is located immediately deep to the trapezius and connects vertebral spinous processes to the medial margins of the scapulae?
rhomboids
What is the name of the fascial layer that envelops the muscles which are part of the erector spinae?
thoraco-lumbar fascia
What actions does the latissimus dorsi muscle effect on the shoulder joint?
Adduction, extension, and medial rotation
Which muscle is needed for starting arm abduction from the anatomical position?
supraspinatus
Where on the scapula does the levator scapulae attach?
superior angle
What part of the trapezius has a role in rotating (tilting) the scapula so that the inferior angle swings laterally, and, what is it needed for?
The superior (descending) part and this is needed to allow full elevation of the arm
What is the name of the gap located between teres major and minor, humerus, and long head of the triceps, through which the axillary nerve travels?
quadrangular space
Which nerve travels close to the shaft of the humerus between the lateral and medial heads of the triceps?
radial
what makes up the borders of the quadrangular space?
teres minor
teres major
long head of triceps
surgical neck of the humerus
which part of the scapula is closest to the ribs?
sub scapular fossa
which muscle is responsible for external/lateral rotation of the glenohumeral joint?
infraspinatus
what cords of the brachial plexus contribute to the median nerve?
medial and lateral cords
what rotator cuff muscle is essential for the initiation of shoulder abduction?
supraspinatus
which part of the brachial plexus gives off the long thoracic nerve?
roots of C6, C7 and C5
