Pectoral Region & Shoulder Flashcards
Osteology in the pectoral region and shoulder
sternum
Clavicle
Scapula
Humerus
Clavicle
Sternal End and Acromial End
Acromial end of clavicle
as travel lateral - this aspect is more flattened
posterior scapula
where there are a lot of bony landmarks
spine - can palpate
Acromium process of scapula
more lateral aspect and will come from the spine as it flattens out and will ARTICULATE with the acromium process of the clavicle
Acromium process of scapula
more lateral aspect and will come from the spine as it flattens out and will ARTICULATE with the acromium process of the clavicle
inferior angle of scapula
where the medial and lateral borders of the scapula come together
suprascapular notch
allow passage of the artery and nerves to pass to the posterior aspect of the scapula
Glenoid Cavity
articulatiung with the head of the humerus
Humeral Head
smooth articular surface
anatomical neck
fused growth plate - proximal and immediately below head
intertubercular groove
bicipital groove
between greater and lesser tubercle
surgical neck
common site of fracture
as you transfer from bulky/bulbous to more narrow shaft to more thin bone
aka site of surgeries
deltoid tuberosity
site of distal attachement of the deltoid
Four joints of the shoulder complex
Sternoclavicular
Acromioclavicular
Glenohumeral
Scapulothoracic
Sternoclavicular Joint Type Articular components Associated structures movements
Articular components: Sternal end of the clavicle and manubrium of sternum MODIFIED TYPE SADDLE JOINT FIBROCARTILAGE DISC Movements: Elevation/Depression Protraction/Retraction
Sternoclavicular Joint Type Articular components Associated structures movements
Articular components: Sternal end of the clavicle and manubrium of sternum MODIFIED TYPE SADDLE JOINT/synovial FIBROCARTILAGE DISC Movements: Elevation/Depression Protraction/Retraction
Fibrocartilage disc in the sternoclavicular joint
This is the ONLY site of bony attachment between the appendicular upper skeleton and the axial skeletion so there is a lot of force coming through to this joint so this fibrocartilage disc helps with that
Acromioclavicular Joint Type Articular components Associated structures movements
Articular components : Acormial end of the clavicle and acromium process of the scapula
Type : plan type synovial joint
Associated structure : fibrocartilage disc (but not as substantial as the sternoclavicular fibrous disc)
Movements: GLIDING between the clavicle and scapula
Glenohumeral Joint Type Articular components Associated structures movements
Articular : Humeral head and glenoid fossa
Type: Ball and socket synovial joint
Movement : THREE PLANES
- flexion and extension
-abduction/adduction
-internal/external rotation
Features: then glenoid fossa is about 1/3 the size of the humeral head
BOTH NON-CONTRACTILE AND CONTRACTILE STRUCTURES ENHANCE THE G-H STABILITY
How does the shoulder joint compensate for being unstable with the difference in size of the glenoid fossa and the bigger size of the humeral head?
Having contractile and non contractile structures to enhance
What plane are the movements of flexion/extension
abduction/adduction and
internal and external rotation in respectively
Sagital
frontal/coronal
Transverse
Non-contractile of the glenhumeral joint
Coracoacromial ligament
Glenohumeral Ligaments
Glenoid labrum
Contractile supporting of the glenhumeral joint
Muscles of rotator cuff
Coracoacromial Ligament
NON-CONTRACTILE
prevents an upward glide
between the coracoid and acromium process and preventing upwards shift when doing over head activities
coracoacromial arch
what forms it and what features are associated with it
tendon?
preventing what?
NON-CONTRACTILE
formed by the smooth inferior aspect of the actomion and the coracoid process of the scapula, with the coracoacromial ligament spanning between them
Preventing SUPERIOR displacement from the glenoid cavity
THE TENDON OF THE SUPRASPINATUS MUSCLE PASSES UNDERNEATH THIS ARCH AND IS AT RISK FOR GETTING SQUEEZED -rotator cuff injury
Glenohumeral ligaments
NON-CONTRACTILE Superior Middle inferior Three reinforcement on the anterior portion which aid in holding the humerus head into the glenoid fossa - helps in the size difference between the two
Glenoid labrum
NON-CONTRACTILE
fibrocartilagenous ring attaching to the margins of the glenoid fossa
-deepens the glenoid cavity
Scapulothoracic (ST) Joint
physiological joint in which movement occurs between muscoskeletal structures (b/w the scapula and associated muscles and the thoracic wall), rather than an ANATOMICAL JOINT
no direct articulation
Coracobrachialis
Attachments
Action
Innervation
Intrinsic muscle of the shoulder Attaches to tip of coracoid process and medial, middle 1/3 of humerus action : flex and adduct the shoulder Innervation by musculocutaneous nerve
POSTERIOR Superficial extrinisc muscles of the shoulder
Trapezius
Latissimus Dorsi
POSTERIOR -Deep layer extrinsic muscles of the shoulder
Levator Scapulae
Rhomboid Major
Rhomboid Minor
POSTERIOR -Deep layer extrinsic muscles of the shoulder
Levator Scapulae
Rhomboid Major
Rhomboid Minor
Trapezius
Attachments
Action
Innervation
Attachments: Superior nuchal line, external occipital protruberance, spinous processes c7-t12
to scapula spine, acromion, and lateral 1/3 clavicle
Action : Upper - elevates and upwardly rotates scapula
middle: adducts/retracts scapula
Lower : depresses and upwardly rotates scapula
Arthrokinematics
refers to movement of joint surfaces
Scapulothoracic movements
Elevation / Depression
Adduction/Retraction and Abduction/Protraction
Upward and Downward rotation
rotation occurs with respect to what
the inferior angle of the scapula which is the joining of the medial border and the lateral/axillary border of the scapula
what joints are moving when we shrug shoulders up and down
elevation/depression
we use the scapulothoracic joint, Sternoclavicular Joint (SC) and the acromiclavicular joint (AC)
shoulder abduction /abduction limitations and planes
coronal plane (0-180 degrees)
Horizontal plane Adduct - 0-45 degrees
Abduct 0-90 degrees
details relating to FULL shoulder abduction
since the subacromial space is so small with the coracoacromial arch with the tough band of fibrous tissue - during full abduction of the arm - we have to laterally rotate our humerus to move the greater tuberosity out of the way - put the lesser in this position.
in neutral position - the grester tubercle is IMMEDEATILY UNDER THIS ARCH. - easier to move with lesser in this area
occurs when putting arm over head
Scapulohumeral Rhythm
Motion available to the glenohumeral joint alone would not account for the full range of motion
Remaineder of motion is CONTRIBUTED BY THE SCAPULOTHORACIC JOINT (VIA THE SC AND AC JOINTS - each joint making its contribution in a specific and consistent pattern known as the scapulohumeral rhythm
if scapula didnt move - humerus would fall right out of the small articulating surface - basically the scapula chasing around the humerus
Range of motion by the GH joint alone
0-30 degrees
Full range of motion of GH with ST contribution - details on contribution
30-180 degrees
past 30 degrees the ST joint has to conribute at least 1 degree of movement for every 2 degress of the GH movement
180 degree arm abduction - what are contributions of the GH and scapula?
GH = 120
ST joints = 60
moves in a 2/1 ration
how does the lower muscle group in the trapezius muscle upwardly rotate the scapula?
even though fibers come from below - they attach superior to the point of rotation - the inferior angle
point of rotation on the scapula
inferior angle
Latissimus Dorsi
Attachments
Action
Innervation
Attachments : Spinous process t7-t12, iliac crest, ribs 9-12
to intertubercular groove of humerus MEDIAL ASPECT
Action - shoulder extension, adduction and internal rotation
Fibers come medially from the back - why we see internal rotation
Innervation : thoracodorsal nerve
Levator Scapulae muscle
Attachments
Action
Innervation
Reflect the trapezius
Attachments : transverse process of C1-C4 to superior medial border of scapula
Action - elevates and downwardly rotates scapula
Innervation - dorsal scapular nerve C5 (think dorsal/deep)
as this is a deep muscle
Rhomboid minor
Attachments
Action
Innervation
Attachments : spinous processes of C7 and T1 to medial scapular border at the level of root scapular spine
Action: Adduct/retract and downwardly rotate scapula
Innervation: Dorsal scapular nerve
Rhomboid Major Attachments
Attachments: Spinous processes T2-T5 to medial scapular border from level of spine to inferior angle
Action and Innervaiton is same as the rhomboid minor
Pectoralis Major
Attachments
Action
Innervation
Attachments - Sterno costal head- anterior sternum, upper six costal cartilages
Clavicular Head - Medial half of clavicle
Action- adducts and medially rotates humerus
Innervation - Medial and Lateral Pectoral Nerves
Pectoralis Minor
Attachments
Action
Innervation
Attachments - Coracoid process of scapula
Ribs 3-5
Action - stabalizes scapula
Innervation - Medial Pectoral Nerve
Serratus Anterior
Attachments
Action
Innervation
Attachments - external surfaces of lateral parts of ribs 1-8 and ANTERIOR surface of medial border of scapula
Action- Protracts and upwardly rotates the scapula, holds scapula against thoracic wall
Innervation - long thoracic nerve (which comes off roots of C5,6,7)
Subclavius
Attachments
Action
Innervation
Attachments - junction of first rib and costal cartilage to inferior surface of medial third of clavicle
Action - anchors and depresses clavicle
Innervation - nerve to subclavius
Intrinisic muscles of the shoulder
- Coracobrachialis
- Deltoid
- Teres Major
- Teres major
- Supraspinatus
- Infraspinatus
- Subscapularis
- These will all have attachments in the shoulder complex bone
Corachobrachialis
Attachments
Action
Innervation
Attachments - Tip of coracoid process to the medial/middle 1/3 of the humerus
Action - flexion and weak adduction
Innervation - Musculocutaneous nerve *FLEXION
Deltoid
Attachments
Action
Innervation
Attachments - Scapula spine, acromium, lateral 1/3 of clavicle to deltooid tuberosity of the humerus
Action - Anterior: shoulder flexion
Middle : Shoulder ABduction
Posterior : shoulder extension
Innervation - AXILLARY NERVE
Teres Major
Attachments
Action
Innervation
Attachments : Inferior lateral aspect of posterior surface of scapula to intertubercle groove of humerus
Action - MEDIAL/ internal rotation (IR)
Innervation - Lower subscapular nerve
Rotator cuff muscles
last 4 acting in a group - SItS Supraspinatus Infraspinatjus teres MINOR Subscapularis
Supraspinatus
Attachments
Action
Innervation
Attachments - supraspinous fossa and greater tubercle
Action - shoulder abduction
Innervation - suprascapular nerve
Infraspinatus
Attachments
Action
Innervation
Attachments - infraspinous fossa and great tubercle
Action - shoulder lateral/external rotation
Innervation - suprascapular nerve
Teres minor
Attachments
Action
Innervation
Attachments - middle part of lateral border of scapula to greater tubercle
Action - shoulder lateral/external rotation
Innervation - axillary nerve
Subscapularis
Attachments
Action
Innervation
Attachments - subscapular fossa to lesser tubercle
Action - shoulder medial/internal rotation (IR)
Innervation - upper subscapular nerve and lower subscapular nerve
quandrangular space
superior border - teres minor
inferior border = teres major
medial border = long head of the triceps brachii
lateral border = surgical neck of the humuerus
How does the GH joint maintain dynamic stability?
Muscles of the Rotator Cuff
- the tendons of the 4 muscles blend with the fibrous capsule forming a cuff which reinforces the joint capsule and provides stability
all four of these muscles provide compressive forces across the GH joint, which provides dynamic stability and maintain the humerus centered within the glenoid fossa
during shoulder elevation which rotator cuff muscles help to stabalize
infraspinatous
teres minor
subscapularis
- all of these have a downaward direction pull thus depress the head of the humerus - this prevents impingement of the rotator cuff under the coracoacromial arch
rotator cuff injury
repetative use of rotator cuff muscles - when using limb above the horizontal - swimming/baseball - may move the humeral head and rotator cuff to impinge under the coracoacromial arch
inflammation of the supraspinatous tendon
