SHOULDER

ANATOMY

Shoulder

• It is a ball and socket

joint that moves in all

three planes:

– Most mobile and least

stable joint.

BONY

ANATOMY

Humerus

• proximal end articulates

with scapula to from

shoulder

• distal end articulates with

bones of the forearm to

form elbow

Shoulder Landmarks

• Humerus-

– Head- is the semi round

proximal end,

articulates with the

scapula.

– Shaft- body of the

humerus is the area

between the neck and

the epicondyles.

Shoulder Landmarks

• Surgical Neck- where the

head meets the body.

• Anatomical neck- where

the head meets the

tubercles.

Shoulder Landmarks• Greater Tubercle/Tuberosity- large

projection lateral to the head.

Supraspinatus, infraspinatus and teres minor

attach here.

Shoulder Landmarks• Lesser Tubercle/Tuberosity- smaller projection on

the anterior surface, subscapularis attaches here.

Shoulder Landmarks• Deltoid tuberosity- lateral side, near the

midpoint, deltoid attaches here.

Shoulder Landmarks

• Bicipital Groove- groove between the

tubercles containing the long head of the

biceps tendon.

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)

Specific Scapular Landmarks

• Medial Border

• Lateral Border

• Superior Border

• Inferior Angle

• Supraspinatus fossa

• Infraspinatus fossa

• Subscapular fossa

• Spine

• Coracoid Process

• Acromion Process

• Glenoid Fossa

• Refer to previous slide

for exact locations

• Also in QUIZLET

Shoulder LandmarksScapula

Glenoid labrum-fibrocartilage ring attached to

the rim of the glenoid fossa, which deepens the

cavity.

Clavicle

• distally articulates with the

acromion process to form the

AC joint

• Proximally articulates with

the sternum to form SC joint

Sternum

• Midline

• Attached to clavicle to

allow for elevation &

depression

MUSCLATURE

Movements

• Flexion & Extension

• Abduction & Adduction

• Internal Rotation & External Rotation

• Horiz. Abduction & Horiz. Adduction

• Protraction & Retraction

• Elevation & Depression

• Circumduction

Group 1 - Muscles

• From the Skeleton to the Humerus

– Latissimus Dorsi

– Pectoralis Major

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

Muscles of the Shoulder Joint

• Latissimus Dorsi-

means widest, back, so

the widest back

muscle. It is mostly

superficial and is

involved with shoulder

extension , adduction

and internal rotation

Pectoralis Major

• the chest muscle

• originates along the

sternum and clavicle,

inserts on the humerus

• it functions to:

~ adduct

~ flex

~medially rotate

the arm.

Muscles of the Shoulder Joint

• Pectoralis Major-

– Clavicular portion-most effective during

flexion from 0-90

– Sternal portion- most effective in extension

180-120 degrees of shoulder extension

– Both of them adduct, internally rotate and

horizontally adduct the shoulder.

Group 2 Muscles

• Scapula to Humerus

– Deltoid

– Teres Major

– Rotator Cuff (SITS)

• Supraspinatus

• Infraspinatus

• Teres Minor

• Subscapularis

– Biceps

– Triceps

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

Muscles of the Shoulder Joint

• Deltoid is superficial muscle. All three parts of it

attach to the deltoid tuberosity.

Rotator Cuff.

• Supraspinatus: 1st 10 degrees of abduction

and external rotation

• Infraspinatus: external rotation

• Teres minor: external rotation

• Subscapularis: internal rotation

Rotator Cuff• Group of four muscles

that act to hold the

head of the humerus

into the glenoid fossa

– Supraspinatus

– Infraspinatus

– Teres Minor

– Subscapularis

** Note that there are no muscles on

the inferior aspect of the shoulder!!

CUFF

• The four rotator cuff

muscles cover the humeral

head and hold the head

against the glenoid fossa.

Rotator Cuff Muscles

• Know these muscles if you remember

nothing else.

– Supraspinatus

– Infraspinatus

– Teres Minor

– Subscapularis

SITS muscles

Rotator Cuff Muscles

• Supraspinatus-anterior superior shoulder. It is superior to the

spine of the scapula.

– abduction

Rotator Cuff Muscles

• Infraspinatus-

– posterior inferior shoulder

region

– Inferior to the spine of the

scapula

– External rotation

– Insertion is greater tubercle of

humerus

Rotator Cuff Muscles

• Teres Minor- posterior

shoulder

– External rotation

– Insertion on greater tubercle

of humerus

Rotator Cuff Muscles

• Subscapularis-anterior

shoulder

– Internal rotation

– Insertion is lesser tubercle of

humerus

Rotator Cuff Muscles

Teres Major

• Teres Major- it is the

little helper of the lats.

It runs from the axillary

boarder of the scapula to

the lesser tubercle of the

humerus.

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

Muscles of the shoulder

• Triceps brachii-

entire muscle mass

of posterior arm. It

attaches to the

olecranon process

when all 3 heads of

the muscle combine.

Function is

extension. Radial

nerve.

Group 3 Muscles

• Scapular Muscles – From the skeleton to the

scapula

• Provides dynamic stability to the shoulder

– Levator Scapula

– Trapezius

– Rhomboids

– Serratus Anterior

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

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

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