Ga - Shoulder

Front 1

Clavicle Proximity

Back 1

The S-shaped clavicle is the most proximal bone of the upper limb.
It is palpable along its entire length in the upper anterior part of the shoulder.

Front 2

Parts of Scapula (5)

Back 2

-The scapula is a triangular bone in the upper posterior part of the shoulder.
-The major parts are the acromion, coracoid process, glenoid cavity, spine, and inferior angle.
-The point of the shoulder (which is the most lateral region of the shoulder's upper surface) acquires its shape from the subcutaneous acromion.

Front 3

Proximal Half of Humerus and parts (5)

Back 3

-Head, greater and lesser tuberosities, intertubercular groove, and surgical neck.
-The surgical neck is the region of the shaft immediately proximal to the insertions of the pectoralis major, teres major, and latissimus dorsi muscles.

Front 4

Axillary Nerve

Back 4

In the upper part of the arm, the axillary nerve lies medial to the surgical nexk of the humerus as it extends posteriorly through a space beneath the fibrous capsule of the shoulder joint. The axillary nerve is the major nerve of the arm most at risk of injury from a fracture of the surgical nexk of the humerus.

Front 5

Sternoclavicular Joint

Back 5

-Joins the medial end of the clavicle with the manubrium of the sternum.
-An articular disc of fibrous cartilage lies between the clavicular and sternal articular surfaces in the joint.

Front 6

Costoclavicular Ligament

Back 6

Attaches the clavicle to the first costal cartilage (which is the bar of hyaline cartilage that joins the first rib to sternum) and stabilizes the sternoclavicular joint by serving as the strongest non-muscular structure binding the clavicle to the rib cage.

Front 7

Acromioclavicular Joint

Back 7

Joins the lateral end of the clavicle to the medial margin of the acromion of the scapula.

Front 8

Coracoclavicular Ligament

Back 8

Attaches the clavicle to the coracoid process of the scapula, stabilizes the acromioclavicular joint by serving as the strongest non-muscular structure suspending the scapula from the clavicle.

Front 9

Shoulder Separations

Back 9

Simple sprains, subluxations (partial dislocations), and dislocations of the acromioclavicular joint are different grades (I - III) of injuries known as shoulder separations. These injuries generally occur as a result of a downward blow on the point of the shoulder.

Front 10

What is seen on the AP (anteroposterior) radiograph of a patient's shoulder?

Back 10

Shows a radiolucent (dark) space called the acromioclavicular space between the acromion and the lateral end of the clavicle. It represents the apposed articular cartilages in the AC joint.
It also shows another radiolucent space between the coracoid process and the clavicle, which marks the location of the coracoclavicular ligament.

Front 11

Grade I Shoulder Separation

Back 11

Is a simple sprain of the fibrous capsule of the acromioclavicular joint. Neither the fibrous capsule nor the coracoclavicular ligament is significantly damaged.
An AP radiograph of this shows acromiclavicular and coracoclavicular spaces of normal width.

Front 12

Grade II Shoulder Separation

Back 12

Subluxation of the acromioclavicular joint. Subluxation occurs when significant damage to the joint's ligamentous supports is limited to its fibrous capsule.
AP radiograph shows coracoclaviular space of normal width but an acromioclavicular space that is at least 50% wider than the contralateral uninjured shoulder.

Front 13

Grade III Shoulder Separation

Back 13

Dislocation of the acromioclavicular joint.
Occurs when both the joint's fibrous capsule and the coracoclavicular ligament are significantly disrupted.
AP radiograph shows the acromioclavicular and coracoclavicular spaces both to be at least 50% wider than the contralateral uninjured shoulder.

Front 14

Shoulder Joint and Glenoid Labrum

Back 14

The shoulder joint joins the head of the humerus with the glenoid cavity of the scapula.
The humeral head also articulates in the joint with the glenoid labrum, a ring of fibrous cartilage that rims the glenoid cavity.

Front 15

Shoulder Dislocations - Most Common Type

Back 15

The shoulder joint is the most commonnly dislocated in adults. Anterior Dislocation of the Humeral Head is the most common type of shoulder joint dislocation.
Anterior dislocation is produced by trauma that drives the humeral head anteroinferiorly from its articulation with the glenoid cavity (head of humerus lies anterior to glenoid cavity and inferior to the coracoid process).

Front 16

Most common type of shoulder dislocation - Injury Description and Associated Nerve

Back 16

The patient presents with a shoulder that has lost its normal rounded contour and acquired the contour of the acromion.
The axillary nerve (which extends posteriorly through a space beneath the fibrous capsule of the shoulder joint) is the major nerve of the arm most at risk of injury from an anterior dislocation of the humeral head.

Front 17

Mechanical role of the clavicle

Back 17

Serves as a strut for the shoulder b/c of its position, shape, and ligamentous attachements to the rib cage and scapula. If no clavicle were present, the shoulder would hang more inferiorly, anteriorly, and medially. But it's there to brace the shoulder superiorly, posteriorly, and laterally.

Front 18

Pectoral Girdle - what is it, how is it moved, and what does it serve as

Back 18

The clavicle and scapula together form a mobile boom called the pectoral girdle for the upper limb.
It is moved about by the muscles that suspent it from the head, neck, back, and chest wall.
It serves as a boom for the upper limb b/c its movements at the sternoclavicular and acromioclavicular joints greatly extend the range of movments of the arm. There are limits to the extent to which the humeral head can be moved in certain directions of the shoulder joint. The muscles that move the pectoral girdle, however, can change the position and orientation of the shoulder joint, and thus extend the range of movements for the arm.

Front 19

Three anatomical features that account for the movement range of the Shoulder Joint

Back 19

The shoulder joint provides more range and freedom of movement than any other synovial joint in the body - for 3 reasons:
1) The shoulder joint has a ball-and-socket configuration in which the humeral head is free to rotate in any direction on the surface of the glenoid cavity
2) The comparatively small surface area of the glenoid cavity enhances the extent to which the humeral head can rotate in any direction on the glenoid cavity. (However, since the surface area of the glenoid cavity is not sufficiently extensive to hold the humeral head in place of the shoulder joint, the joint can be easily dislocated)
3) The joint has a comparatively lax fibrous capsule (another factor as to why the joint can be easily dislocated)

Front 20

Shoulder Arm Movements provided by the sternoclavicular joint

Back 20

-It permits upward and downward rotation of the clavicle at the joint. Upward and downward rotation of the clavicle at the sternoclavicular joint raises and lowers the pectoral girdle, which in effect Raises And Lowers The Shoulder.
-It permits forward and backward rotation of the clavicle at the joint. Forward and backward rotation of the clavicle at the sternoclavicular joint moves the pectoral girdle horizontally forward and backward around the rib cage. These movments move the shoulder horizontally forward and backward around the rib cage. Horizontal forward movement of the shoulder is called Protraction of the Shoulder, and horizontal backward movement is called Retraction of the Shoulder.

Front 21

The sternoclavicular, acromioclavicular, and shoulder joints are all involved in...

Back 21

Abduction and Adduction of the Arm.
During arm abdction, the clavicle and scapula together are rotated upward at the sternoclavicular joint at the same time as the humerus is rotated upward at the shoulder joint. These movements are all reversed in arm adduction.

Front 22

Lateral and Medial Rotation of the Scapula

Back 22

The upward rotation of the clavicle and scapula at the sternoclavicular joint during arm abduction swings the inferior angle of the scapula upward and laterally called Lateral Rotation of the Scapula.
The reverse movment which occurs during arm adduction is called Medial Rotation of the Scapula.

Front 23

Scapulorhumeral Rhythm

Back 23

On average during arm abduction, lateral rotation of the scapula contributes 1 degree arm abduction for every 2 degree arm abduction provided by upward rotation of the humerus. Orthopedic surgeons refer to the coordinated movements of the scaupla and humerus during arm abduction and adduction as Scapulohumeral Rhythm.

Front 24

Shoulder Arm Movements provided by the Shoulder Joint

Back 24

-Permits forward and backward rotation of the humerus at the joint, which in turn Flexes and Extends the Arm.
-Permits internal and external rotation of the humerus at the joint, which in turn Internally Rotates and Externally Rotates the Arm.

Front 25

Cleidocranial Dysostosis

Back 25

A hereditary condition characterized by defective ossification of cranial bones and the clavicle; the defect can cuase complete absence of the clavicles. Without clavicles, the individual can move his shouldersso far anteriorly and medially that they come almost in contact with each other in front of the chest.

Front 26

Clavicular Fractures - why, where

Back 26

The clavicle is always involved in transmitting forces from the upper limb to the body trunk when a person uses the upper limb to brace the body during accidental collisions and falls. This is one reason why the clavicle is the most commonly fractured bone of the body. Most clavicular fractures occur between the clavicular attachments of the costoclavicular and coracoclavicular ligaments. Because a fracture of the clavicle proximal to the coracoclavicular ligament abolishes the clavicle’s strut role for the shoulder, a person with such a fracture presents with a shoulder that (by virtue of its mass and lack of support) is displaced inferiorly, anteriorly, and medially.

Front 27

Shoulder Muscles that Suspend the Pectoral Girdle from the Vertebral Column (4)

Back 27

1) Trapezius
2) Levator Scapular
3) Rhomboid Major
4) Rhomboid Minor

Front 28

Trapezius - innervation, responsibities/functions (3)

Back 28

-Is the major muscle that suspends the upper limb from the vertebral column
-Innervated by the Accessory Nerve.
-It is chiefly responsible for the ability to raise (to shrug) the shoulder.
-It is 1 of 2 prime movers for lateral roation of the scapula, thus providing much of the force required to raise the arm above the shoulder.
-It can also lower the shoulder and retract the shoulder.

Front 29

Levator Scapulae - innervation, responsibities/functions (2)

Back 29

-It is innervated by the Dorsal Scapular Nerve (C5) and Nerve Fibers from C3 and C4
-It assists the trapezius in raising the shoulder.
-Can medially rotate the scapula (opposite of lateral rotation of scapula)

Front 30

Rhomboid Major and Minor - innervation, responsibities/functions (2)

Back 30

-Innervated by the Dorsal Scapular Nerve (C5)
-Both can retract the shoulder
-Both can medially rotate the scapula

Front 31

Shoulder Muscles the Pull on the Pectoral Girdle from the Anterior Chest Wall (3)

Back 31

1) Serratus Anterior
2) Pectoralis Minor
3) Subclavius

Front 32

Serratus Anterior - innervation, responsibities/functions (3)

Back 32

-Innervated by the Long Thoracic Nerve
-one of the two prime movers for lateral rotation of the scapula, and thus provides much of the force required to raise the arm above the shoulder.
-prime mover for protraction of the shoulder
-holds the scapula firmly against the rib cage when the outstretched upper limb pushes anteriorly (such an anterior push occurs during push-up exercises).

Front 33

Serratus Anterior Paralysis

Back 33

resulting from transection of the long thoracic nerve may occur during a radical mastectomy (a surgical procedure in which the entire breast as well as the pectoral muscles and the axillary lymph nodes are excised). Serratus anterior paralysis results in pronounced flaring of the scapula (in particular, the inferior angle) when the outstretched upper limb pushes anteriorly. The pronounced flaring is frequently referred to as a Winged Scapula.

Front 34

Pectoralis Minor - innervation, functions (2)

Back 34

-Innervated by the Medial Pectoral Nerve
-Can lower the shoulder and protract the shoulder.

Front 35

Subclavius - innervation, functions (1)

Back 35

-Innervated by the Nerve to Subclavius
-Can lower the shoulder

Front 36

Muscles of the Rotator Cuff (4) and why they are called so (2)and how they deal with their lack of power

Back 36

1) Supraspinatus
2) Infraspinatus
3) Teres Minor
4) Subscapularis
These are called the called the muscles of the rotator cuff because (a) their tendons of insertion form a musculotendinous cuff about the shoulder joint and (b) three of the muscles can externally or internally rotate the arm.
These muscles serve to stabilize the dynamic integrity of the shoulder joint by maintaining the humeral head in proper apposition to the glenoid cavity when the powerful prime movers of the arm extert their forces across the joint.

Front 37

Supraspinatus - Innervation and function (2)

Back 37

-innervated by the Suprascapular Nerve (C5 and C6)
-initiates abduction of the arm at the shoulder joint from the anatomical position
-assists deltoid in further arm abduction at the shoulder joint

Front 38

Infraspinatus - Innervation and function (1)

Back 38

-innervated by the Suprascapular Nerve (C5 and C6)
-Can externally rotate the arm.

Front 39

Teres Minor - Innervation and function (1)

Back 39

-Innervated by the Axillary Nerve (C5 and C6)
-Can externally rotate the arm

Front 40

Subscapularis - Innervation and function (1)

Back 40

-Innervated by the Upper and Lower Subscapular Nerves.
-Can internally rotate the arm.

Front 41

Subacromial Space

Back 41

o When the arm is abducted at the shoulder joint, the supraspinatus muscle and the soft tissues about it are drawn proximally into the subacromial space, which is the space underlying the acromion and coracoacromial ligament

Front 42

Coracromial Ligament

Back 42

a ligament that extends from the coracoid process of the scapula to the acromion; the ligament overlies the shoulder joint.

Front 43

Variations in height of the subacromial space

Back 43

The height of the subacromial space varies with the position of the arm at the shoulder joint;
It becomes narrowest when the arm is simultaneously abducted, flexed, and internally rotated.
This position is called the Impingement Position because it is the arm position in which supraspinatus’s insertion tendon and the subacromial bursa both become compressed, or impinged, against the overlying acromion and coracoacromial ligament.

Front 44

Subacromial Bursa

Back 44

a bursa that separates the supraspinatus tendon of insertion from the overlying acromion and deltoid muscle)

Front 45

Subacromial Impingement Syndrome

Back 45

-Can lead to a number of primary lesions, such as an incomplete tear of the supraspinatus tendon of insertion, supraspinatus tendonitis, or subacromial bursitis.
-Is also called the painful arc syndrome because a patient suffering from one of the most common primary lesions of the syndrome typically experiences subacromial pain when the arm is abducted (either actively or passively) through the 60o to 120o arc.

Front 46

Prime Movers of Abduction and Adduction of the Arm at the Shoulder Joint (4)

Back 46

1) Deltoid
2) Pectoralis Major
3) Teres major
4) Latissimus Dorsi

Front 47

Deltoid - Innervation and functions (2)

Back 47

-Innervated by the Axillary Nerve (C5 and C6 spinal nerves supply this innervation nerve)
-the prime mover for abduction of the arm at the shoulder joint.
-Deltoid can also flex, internally rotate, extend, and externally rotate the arm.

Front 48

Abduction of the arm at the shoulder joint is controlled mainly by which spinal nerve fibers and why?

Back 48

Abduction of the arm at the shoulder joint is controlled mainly by C5 nerve fibers because supraspinatus and deltoid, which are the only muscles involved in abduction of the arm at the shoulder joint, each receive more innervation from C5 than C6 nerve fibers.

Front 49

Pectoralis Major - Innervation and function (1)

Back 49

-Innervated by the Medial and Lateral Pectoral Nerves
-Can flex, adduct, and internally rotate the arm

Front 50

Teres Major - Innervation and function (1)

Back 50

-Innervated by the Lower Subscapular Nerve.
-Can adduct and internally rotate the arm

Front 51

Latissimus Dorsi - Innervation and function (1)

Back 51

-Innervated by the Thoracodorsal Nerve.
-Can extend, adduct, and internally rotate the arm.