SHOULDER
ANATOMY
BONY
ANATOMY
Humerus
• proximal end articulates
with scapula to from
shoulder
• distal end articulates with
bones of the forearm to
form elbow
Scapula
• the shoulder blade
Glenoid fossa has ring of
cartilage called labrum to
deepen the articular surface
• the glenoid fossa of the
scapula articulates with the
humerus to form the
glenohumeral joint (shoulder)
• the acromion process
articulates with the clavicle to
from the acromioclavicular
joint (tip of the shoulder)
Clavicle
• distally articulates with the
acromion process to form the
AC joint
• Proximally articulates with
the sternum to form SC joint
Review of Joints
• Glenoid fossa+humerus=glenohumeral joint (GH)
(scapula)
• Acromion process + clavicle =acromioclavicular
(scapula)
(AC)
• Sternum + clavicle=sternoclavicular (SC)
• Scapula+rib cage= scapulothoracic articulation
MUSCLATURE
Trapezius
• large, triangular
muscle
• starts at base of
skull, runs out to tip
of shoulder and
down to the 12th
thoracic vertebrae
• functions to shrug
and square the
shoulders
Rhomboids
• group of two
muscles that run
diagonally from the
spine to the medial
border of the scapula
• they function to
retract the scapula
Latissimus Dorsi
• the “lats”
• gives wing like
appearance to sides
• starts along the
thoracic vertebrae of
back and inserts on the
anterior aspect of
humerus
• functions extend ,
adduct and medially
rotate the arm
Pectoralis Major
• the chest muscle
• originates along the
sternum and clavicle,
inserts on the humerus
• it functions to:
~ adduct
~ flex
~medially rotate
the arm.
Deltoid
• the muslce that gives
contour to the shoulder
• originates along the
spine of the scapula and
clavicle, inserts on the
humerus
• all fibers abduct the
arm
• anterior fibers: flex
and medially rotate arm
• posterior fibers: extend
and laterally rotate arm
Biceps
• the “popeye” muscle
• on anterior aspect of
arm
• crosses both the
shoulder and elbow
• flexes the arm
Triceps
• on the posterior aspect
of the arm
• crosses both the
shoulder and elbow
• extends the arm
Rotator Cuff
• Group of four muscles
that act to hold the
head of the humerus
into the glenoid fossa
– Supraspinatus
– Infraspinatus
– Teres Minor
– Subscapularis
Rotator Cuff cont.
•
•
•
•
Supraspinatus: 1st 10 degrees of abduction
Infraspinatus: external rotation
Teres minor: external rotation
Subscapularis: internal rotation
** Note that there are no muscles on
the inferior aspect of the shoulder!!
This will be important when we talk
about shoulder injuries
Labrum
• Ring of cartilage similar to the menisci of the
knee.
• Deepens the articular surface of the genoid
fossa and adds to the stability of the shoulder