anatomy #3

clinical importance of shoulder and upper limb

-frequent trauma to these regions

-vessels used as pressure sites

-vessels used for drawing blood, administering fluids, nutrients, medicine

shoulder and upper limb divided into these areas

-shoulder

-axilla (armpit)

-arm

-forearm

-hand

appendicular skeleton

includes bones of the limbs and the girdles of bones that attach limbs to axial skeleton

shoulder girdle 

-articulates with the trunk and supports the upper limbs

-serve as a base for function of upper extremity

shoulder girdle consists of 

clavicles and scapulae

key bony landmarks of shoulder girdle

-manubrium

-clavicle

-coracoid process

-acromion process

-glenoid fossa

-lateral border

-inferior angle

-medial border

clavicle

-collarbone

-s-shaped bone

-easily palpated

-braces shoulder

-most commonly fractured bone

conoid tubercle of clavicle

articulates medially with the manubrium of sternum and laterally with the acromion

scapula

-shoulder blade

-scapula is a broad, flat triangle; three borders and two angles, superior, medial, lateral borders, inferior, superior angles

-spine of the scapula

-glenoid fossa (cavity)

glenoid fossa (cavity)

articulates with head of humerus

other features of scapula (for muscle and ligament attachment)

-posterior: bony ridge= spine; supraspinous fossa is above it, intraspinous fossa is below it

-lateral: acromion process

-anterior projection: coracoid process; biceps attachment

-subscapular fossa is anterior surface

shoulder girdle joints

-sternoclavicular (SC) joint

-acromioclavicular (AC) joint

-scapulothoracic joint

sternoclavicular (SC) joint

-joint between manubrium of sternum and sternal end of the clavicle

-articular disc separates two joint cavities

-wide range of movements; anteriorly 15 degrees with protraction, posteriorly 15 degrees with retraction, in some slight rotary gliding movements

sternoclavicular ligaments

-sternoclavicular

-costoclavicular

-interclavicular

acromioclavicular (AC) joint

-joint between acromial end of clavicle and acromion of scapula

-articular disc within joint cavity

-20 to 30 degree total gliding and rotational motion accompanying other shoulder girdle and shoulder joint motions

-often injured

AC ligaments

-acromioclavicular

-Coracoclavicular

acromioclavicular ligament

hold joint together

coracoclavicular ligament

-trapezoid (lateral)

-conoid (medial); limit movement

shoulder separation

acromioclavicular and coracoclavicular ligaments

scapulothoracic joint

-scapula moves on the rib cage

-movement depends on SC and AC joints which allows the scapula to move; 25 degree abduction-adduction, 60 degree upward-downward rotation, 55 degree elevation-depression

-supported dynamically by its muscles

-no ligamentous support

scapula ligaments

-superior transverse scapular

-inferior transverse scapular

-coracoacromial

superior transverse scapular ligament

suprascapular nerve passes through

inferior transverse scapular ligament

suprascapular nerve passes through

coracoacromial ligament

limits superior movement of humeral head

shoulder girdle movements= scapula movements

-wherever scapula goes, clavicle follows

-elevation

-depression

-protraction

-retraction

-upward rotation

-downward rotation

protraction

upward rotation and lateral tilt

retraction

downward rotation and medial tilt

upward rotation

turning glenoid fossa upward and moving inferior angle superiorly and laterally away from spinal column to assist in raising arm

downward rotation

returning inferior angle medially and inferiorly toward spinal column and shoulder to its normal position

shoulder girdle muscles

-5 muscles are primarily involved in shoulder girdle movements

-all originate on axial skeleton and insert on scapula or clavicle

-do not attach to humerus and do not cause shoulder joint actions

-essential in providing dynamic stability of scapula so it can serve as base of support for shoulder joint activities

scapula muscles are important in spinal posture

-forward shoulder is due to scapular protractors and depressors becoming stronger and tighter and retractors becoming weaker; contributes to kyphosis, less function position for shoulder joint

-important to maintain lumbar lordosis and keep the head over the trunk in a balanced position

-good posture enhances inspiration

anterior shoulder girdle muscles

-pectoralis minor

-serratus anterior

-subclavius

pectoralis minor

O: 3rd-5th ribs

I: coracoid process (scapula)

A: downward scapular rotation

serratus anterior

O: anterior/ lateral aspects of upper 9 ribs

I: anterior surface of medial scapula border

A: scapular abduction, upward rotation

subclavius

O: 1st rib

I: subclavian (inferior) groove of clavicle

A: stabilization of SC joint

posterior shoulder girdle muscles

-levator scapulae

-rhomboids (major and minor)

-trapezius

levator scapulae

O: transverse processes of 1st-4th cervical vertebrae (C1-C4)

I: medial, superior vertebral border of scapula

A: scapular elevation, downward rotation

rhomboids (major and minor)

O: spinous processes of the C7-T5

I: medial border of the scapula

A: scapular elevation, downward rotation

*also has function on the spine

trapezius

O: external occipital protuberance and C7-T12 vertebrae

I: spine of scapula, acromion process, posterior surface of clavicle

A: upper- scapular elevation, middle- scapular adduction, lower- scapular depression, upward rotation

*also has function on the spine

humerus proximal features

-head

-anatomical and surgical necks

-greater and lesser tuberosities

-intertubercular groove

head of humerus

articulates with scapula

greater and lesser tuberosities

for muscle attachment

intertubercular groove

for passage of biceps brachii tendon and muscle attachment

shaft of humerus

deltoid tuberosity

deltoid tuberosity

attachment of deltoid muscle

glenohumeral joint

-shoulder joint

-diarthrodial ball-and-socket joint between head of humerus and glenoid cavity of scapula

-attached to axial skeleton via SC joint

features of glenohumeral joint

-fibrocartilaginous glenoid labrum

-ligaments: capsular, glenohumeral, coracohumeral

-tendon of biceps brachii

-rotator cuff muscles

-bursae: subacromial, subcoracoid, sub deltoid, and sub scapular

glenoid lip

glenoid labrum

glenoid labrum

-ligament forms edge around glenoid of scapula

-helps deepen glenoid fossa for shoulder joint

-increases stability

-injured with sudden overhead movements and with trauma

capsular (glenohumeral joint ligaments)

anatomical neck of humerus and glenoid fossa

glenohumeral (glenohumeral joint ligaments)

beneath capsule

-superior glenohumeral

-middle glenohumeral

-inferior glenohumeral

coracohumeral (glenohumeral joint ligaments)

anatomical neck and coracoid

humerus ligaments

transverse humeral

transverse humeral

-crosses intertubercular groove

-holds tendon

-O: long head of bicep is groove

shoulder injury

-frequently injured due to anatomical design

-posterior instability problems somewhat common

-anterior dislocation most common (excess abduction, external rotation)

-posterior dislocation (excess adduction, internal rotation)

-downward dislocation (abduction)

stability of shoulder is sacrificed for mobility

-shallowness of glenoid fossa

-laxity of ligamentous structures

-lack of strength and endurance in muscles

shoulder joint movements

-flexion

-extension

-abduction

-adduction

-internal rotation

-external rotation

shoulder joint muscles

-intrinsic glenohumeral muscles

-extrinsic glenohumeral muscles

intrinsic glenohumeral muscles

-originate on scapula and clavicle

-deltoid, coracobrachialis, teres major

-rotator cuff group 

rotator cuff group

-subscapularis

-supraspinatus

-infraspinatus

-teres minor

extrinsic glenohumeral muscles

latissimus dorsi and pectoralis major

anterior shoulder muscles are

major shoulder flexors

anterior shoulder muscles

-pectoralis major

-coracobrachialis

-subscapularis

-biceps brachii

pectoralis major

O: 1st-6th ribs, sternum, medial half of clavicle

I: anterior area of surgical neck of humerus (intertubercular groove of humerus)

A: shoulder flexion, adduction, internal rotation

coracobrachialis

O: coracoid process of scapula

I: medial side of humerus

A: shoulder flexion, adduction

subscapularis

O: sub scapular fossa of scapula

I: lesser tubercle of humerus

A: shoulder internal rotation

biceps brachii

O: long head- supraglenoid tubercle of scapula; short head- coracoid process of scapula

I: radial tuberosity

A: long head- shoulder flexion, abduction; short head- shoulder flexion, adduction

*additional actions at the elbow

superior shoulder muscles are

major shoulder abductors

superior shoulder muscles

-deltoid

-suprapinitus (beneath the deltoid)

deltoid

O: anterior- (clavicular) lateral/ anterior clavicle; middle- (acromial) acromion process of scapula; posterior (scapular) inferior edge of scapular spine

I: deltoid tuberosity of humerus

A: entire deltoid- abduction; regions- several actions

*frequent site for IM injections

supraspinitus

O: supraspinous fossa of scapula

I: greater tuberosity of humerus

A: shoulder abduction

posterior shoulder muscles are

major shoulder extensors

posterior shoulder muscles

-infraspinatus

-teres minor

-rotator cuff muscles

infraspinatus

O: infraspinous fossa of scapula

I: middle facet of the greater tubercle of humerus

A: shoulder external rotation, extension

teres minor

O: upper/ middle portion of lateral border of scapula

I: greater tubercle of humerus

A: shoulder external rotation, extension

SITS

helps remember insertions (superior, middle, inferior facets of the greater tubercle, lesser tubercle of humerus)

rotator cuff muscles

-insert on musculotendinous structure running between facets located on lesser and greater tuberosities on humerus

-give movement and stability

rotator cuff injury

rotator cuff is frequently injured

rotator cuff is frequently injured

-not very large

-vital in maintaining humeral head in correct position while more powerful muscles move humerus through its wide range of motion

-must possess strength and muscular endurance

-conducting repetitious overhead activities (throwing, swimming, pitching) with poor technique, muscle fatigue or inadequate warm-up and conditioning leads to failure of rotator cuff muscle group in dynamically stabilizing humeral head in glenoid cavity

-leads to further rotator cuff problems such as tendinitis and rotator cuff impingement within subacromial space

inferior shoulder muscles are

major shoulder adductors

inferior shoulder muscles

-latissimus dorsi

-teres major

-triceps brachii

latissimus dorsi

O: spinous processes of lower 6 thoracic and all lumbar vertebrae, posterior ilium, sacrum, lower 3 ribs, inferior angle of scapula

I: intertubercular groove on anterior aspect of humerus

A: shoulder internal rotation, extension, adduction

*also has function on the spine

teres major

O: inferior angle of the scapula

I: inferior to the lesser tuberosity on the humerus (intertubercular groove)

A: shoulder internal rotation, extension, adduction

triceps brachii

O: long head- infraglenoid tubercle of scapula, lateral head- posterior shaft of the humerus, medial head- posterior shaft of the humerus

I: common tendon into the olecranon process of the ulna

A: shoulder extension, adduction

distal features of humerus

condyles that articulate with forearm bones

-capitulum

-trochlea

medial and lateral epicondyles for muscle attachments

capitulum

round, lateral projection for articulation with radius

trochlea

pulley-shaped, medial projection for articulation with ulna

fossae to accommodate projections of forearm bones (humerus)

radial fossa (on anterior humerus): accommodates head of radius

coronoid fossa (on anterior humerus): accommodates coronoid of ulna

olecranon fossa (on posterior humerus): large basin that accommodates olecranon of ulna

forearm

bones of the forearm

-in the anatomic position, they are parallel= in supination

• the radius is lateral to the ulna

-pronation involves the radius crossing over the ulna

• palm faces posteriorly

-ulna is much larger proximally than radius

-radius is much larger distally than ulna

radius

proximal features:

-head

-neck

-radial tuberosity

distal features:

-styloid process

-ulnar notch

head of radius

articulates with capitulum of humerus

neck of radius

narrowest region

radial tuberosity of radius

for biceps brachii muscle attachment

styloid process of radius

lateral “wrist bump”

ulnar notch of radius

medial dent for head of ulna

ulna

proximal features:

-trochlear notch

-olecranon

-coronoid process

-radial notch

distal features:

-head

styloid process

trochlear notch of ulna

accommodates trochlea of humerus

olecranon of ulna

projection that forms the posterior “bump” of the elbow; attachment site for triceps brachii

coronoid process of ulna

inferior lip of trochlear notch

radial notch of ulna

lateral; accommodates head of radius