Shoulder/Arm Anatomy Flashcards
first bone to ossify
clavicle at 5 weeks gestation
when does the medial epiphysis of the clavicle fuse?
25 years of age
what type of joint is the AC?
gliding fibrocartilagenous
maximum rotation of the AC joint
5-8° (with shoulder elevation)
which displacement does the AC ligament prevent?
AP displacement
*the conoid and trapezoid prevent superior displacement
6 types of AC joint injuries
1 = sprain, no ligamentous disruption
2 = AC disrupted, CC intact, < 50% subluxation
3 = AC and CC disruption with dislocated AC joint
4 = through trapezius
5 = detachement of deltoid and trapezius, extreme elevation of clavicle
6 = inferior displacement of clavicle
what type of joint is the SC?
diarthroidal with intraarticular disk
what is the ROM of the SC joint?
30° superior/inferior/AP
45° rotational
interclavicular ligament
anterior sternoclavicular ligament (there is also a posterior, not seen here)
costoclavicular ligament
suproglenoid notch
glenoid notch
spinoglenoid notch
6 ligaments that attach to scapula
CC x 2
CA
CH
superior transverse scapular ligament (army over, navy under)
inferior transverse scapular ligament (spinoglenoid notch)
orientation of the scapula in space
30° anterior in the axial plane
3° upward tilt
7° glenoid retroversion in most (75%) people (interestingly, the other 25% have varying degrees of anteversion at 2-10°)
neck-shaft angle of humerus
130-150°
retroversion of the humerus compared to the transepicondylar axis
30°
what comprises the conjoint tendon of the shoulder?
the coracobrachialis and short head of biceps as they attach to the coracoid process
deltoid tuberosity
subscapularis
lat dorsi
teres major
coracobrachialis
brachialis
brachioradialis
deltoid
pec major
supraspinatus
transverse humeral ligament
supraspinatus
infraspinatus
teres minor
triceps brachii
deltoid
brachialis
triceps medial head
radial groove
major blood supply to the humeral head
arcuate artery from the anterior circumflex humeral artery, which comes off the axillary artery
17 muscles that attach to the scapula
rhomboid major
rhomboid minor
levator scapula
trapezius
lat dorsi
serratus anterior
supraspinatus
infraspinatus
teres minor
teres major
subscapularis
omohyoid
pec minor
coracobrachialis
biceps
triceps long head
deltoid
trapezius
deltoid
triceps long head
teres minor
teres major
lat dorsi
rhomboid major
infraspinatus
rhomboid minor
supraspinatus
levator scapulae
omohyoid
pec minor
serratus anterior
subscapularis
conjoint tendon (coracobrachialis and biceps short head)
describe the glenoid
pear-shaped
35 mm vertical height
25 mm transverse width
1/3 the surface area of the humeral head
what is the function of the glenoid labrum?
increases depth of joint 50%
anchor point for capsuloligamentous structures
4 static restraints of the glenohumeral joint
bony anatomy
labrum
negative pressure
capsular ligaments
3 dynamic restraints of the glenohumeral joint
rotator cuff
biceps tendon
scapulothoracic motion
long head of biceps tendon
SGHL
subscapularis tendon
IGHL
MGHL
weitbracht’s foramen
draw the brachial plexus
SGHL origin and insertion
originates with the superior labrum and biceps tendon
inserts to LT
function of SGHL
resists inferior translation in adducted arm
SGHL
MGHL
anterior band of IGHL
IGHL
posterior band of IGHL
MGHL origin and insertion
arises deep to subscapularis insertion
inserts anterior humerus adjacent to LT
function of MGHL
effective at 45°
limits ER, inferior translation, anterior translation
function of IGHL
prevents anterior, inferior and posterior translation at 90° abduction
*anterior band prevents anterior-inferior dislocation
*posterior band prevents posterior-inferior dislocation
what is the coracohumeral ligament?
from base of coracoid to anatomic neck of humerus
assists SGHL
restricts external rotation in adduction and inferior translation in adduction
what is a buford complex?
2% of population
congenital absence of anterosuperior labrum
MGHL becomes cord-like to replace it
can be misinterpreted as a labral tear
where is the rotator interval?
triangular portion of the capsule between supraspinatus and subscapularis tendons
reinforced by CHL and SGHL
4 muscles connecting thoracic wall to upper limb
pec minor
pec major
subclavius
serratus anterior
6 muscles connecting the vertebral column to the upper limb
trapezius
lat dorsi
rhomboid minor
rhomboid major
lev scap
SCM
SCM origin and insertion
origin: medial 1/3 clavicle and sternum
insertion: mastoid process
trapezius origin and insertion
origin: EOP, nuchal line, SPs of C7-T12
insertion: spine scapula, distal 1/3 clavicle
rhomboids origin and insertion
origin: major from T2-5 SP, minor from C7-T1 SP
insertion: medial scapula
lev scap origin and insertion
origin: TP C1-4
insertion: superomedial scapula
lat dorsi origin and insertion
origin: SP T6-S5
insertion: crest of LT
pec origin and insertion
origin: major from calvicle, sternum, ribs 1-7, minor from ribs 1-3
insertion: crest of GT and coracoid respectively
serratus anterior origin and insertion
origin: all ribs
insertion: medial scapula
subclavius origin and insertion
origin: rib 1
insertion: inferior clavicle
deltoid origin and insertion
origin: clavicle, acromion, spine of scapula
insertion: deltoid tuberosity
teres major origin and insertion
origin: lateral border of scapula
insertion: crest of LT
insertion of subscapularis
LT
insertion of coracobrachialis
proximal medial 1/2 humerus
brachialis origin and insertion
origin: anterior distal 1/2 humerus
insertion: ulnar tuberosity
origin of lateral triceps head
superolateral humerus
origin of medial head triceps
inferomedial humerus
2 posterior cord branches of the brachial plexus
radial
axillary
nerve arising from the lateral cord
musculocutaneous
the brachial plexus arises from between which two muscles?
anterior and middle scalene
function of the dorsal scapular nerve
lev scap
rhomboid major
rhomboid minor
function of the suprascapular nerve
supraspinatus
infraspinatus
function of the LTN
serratus anterior
function of nerve to subclavius
subclavius
course of the suprascapular nerve
through the scapular notch then the spinoglenoid notch to innervate supra and infra
*also supplies sensory function to the shoulder joint
where does the LTN travel?
superficial to serratus anterior on the chest wall
what is Horner syndrome?
avulsion/compression of C8-T1 roots
leads to anhydrosis, ptosis and miosis
medial scapular winging
LTN palsy
lateral scapular winging
either dorsal scapular nerve or accessory nerve palsy
where is the nerve to subclavius?
anterior to plexus but posterior to clavicle
5 short branches of the brachial plexus that leave inferior to the clavicle (i.e. at cord level)
subscapular
thoracodorsal
medial and lateral pectoral
MBC
MABC
source of subscapular nerve
C5-6 via the posterior cord
travels on subscapularis
source of thoracodorsal nerve
C6-8 via posterior cord between the upper and lower subscapular nerves
runs inferolateral along posterior axillary wall to lat dorsi
source of pec nerves
C5-T1
discuss musculocutaneous nerve
from C5-7
to coracobrachialis, biceps and brachialis
lateral antebrachial cutaneous nerve sensation lateral forearm
articular branches to anterior joint capsule
arises from lateral cord
pierces CB 5-8 cm distal to coracoid
travels between biceps and brachialis
discuss axillary nerve
from C5-6
for deltoid, teres minor
sense for herald patch (superior lateral brachial cutaneous nerve)
from posterior cord
wraps around surgical neck
through quad space
gives off superior and inferior branches to delt and T minor respectively
discuss radial nerve
C5-T1
from posterior cord
joins deep brachial artery in triangular interval
goes posterior 10-14 cm from lateral condyle
goes medial to lateral in the spiral groove
enters anterior compartment
travels between brachialis and brachioradialis
emerges anteriorly and bifurcates at radiocapitellar joint
deep branch goes into supinator canal and continues as PIN
superficial branch follows the radial artery along brachioradialis
contributes to brachialis* + all extensors
is functionally PIN for ECRB and everything distal
sensory to shoulder, wrist, 4 MCP joints
sensory post BC, inf lat BC, post ABC, dorsal digitals, ulnar comm branch
discuss ulnar nerve
from C8-T1
sensory for capsule of elbow and CMC joints
sensory for dorsal digital nerves, palmar branch to common and proper palmar branches
arises from medial cord
pierces medial intermuscular septum 8 cm from medial condyle to go posterior
behind medial epicondyle in the cubital tunnel
travels between FCU heads
penetrates the deep flexor-pronator aponeurosis
travels deep to FDS and FCU on FDP
enters the wrist at Guyon’s canal
discuss median nerve
C6-T1
from medial and lateral cords
runs along anterior surface of medial intermuscular septum
crosses medial to brachial artery in cubital fossa
passes between 2 heads of pronator teres
runs between FDS and FDP
through carpal tunnel
muscles of hand direct from median, FPL, PQ and 1/2 FDP are AIN
sensory for elbow and wrist joints
sensory via palmar branch, comm branch, common and proper digital nerves
what is Erb palsy?
C5/6 lesion
results in deltoid/ anterior arm weakness as the axillary and MSK nerves are taken out
looks like a waiter’s tip because of unopposed extensors and pronators
what is klumpke palsy?
C8-T1 lesion
results in unopposed flexion, loss of intrinsic hand strength and possible Horner’s syndrome
will look like flexed arm with clawed hand
which portion of the axillary artery is most vulnerable to injury?
third part - lateral to pec minor
5 important branches of the axillary artery
supreme thoracic
thoracoacromial
lateral thoracic
subscapular
anterior and posterior circumflex humeral
thoracoacromial artery
supreme thoracic artery
lateral thoracic artery
subscapular artery
posterior and anterior humeral circumflex arteries
quadrangular space
triangular interval
triangular space
borders of the quadrangular space
superior: teres minor
inferior: teres major
lateral: humerus
medial: long head of triceps
what passes through the quadrangular space?
axillary nerve
posterior humeral circumflex artery
borders of the triangular space
superior: teres minor
inferior: teres major
lateral: long head triceps
what travels through the triangular space?
circumflex scapular artery
borders of the triangular interval
superior: teres major
lateral: humerus
medial: long head triceps
what passes through the triangular interval?
radial nerve
profunda brachii artery
