Shoulder, Posterior Arm And Forearm, And Joints

Question 1

Superficial Back Muscles

Answer 1

Latissimus Dorsi
Teres Major

Both Muscles travel from the posterior aspect of the body to the anterior humerus. Result: both adduct and medially rotate the humerus

Trapezius

Levator Scapulae
Rhomboid Minor
Rhomboid Major
All 3 muscles attach to the medial border of the scapula

Question 2

Shoulder-Deltoid

Answer 2

3 fibers: anterior, middle and posterior

The mult. Attachment sites of the deltoid muscle allow it to perform several actions, including some that are antagonistic

Question 3

Anterior Shoulder Muscles

Answer 3

Supraspinatous

Subscapularis

Question 4

Posterior Shoulder Muscles

Answer 4

Supraspinatous*
Infraspinatus
Teres minor
Teres Major

Keep in mind the diff. Humeral attachment sites for the teres muscle. The posterior humeral attachment of the teres minor muscle allows it to LATERALLY rotate the arm, while the anterior attachment of the teres major muscle will MEDIALLY rotate the arm

(Triceps brachii)

Question 5

Rotator Cuff Muscles

Answer 5

Supraspinatus, infraspinatus, teres minor and subscapularis
(SITS)

They function to hold the humeral head in the glenoid cavity during shoulder movement. Injury can occur with overuse (e.g. Baseball pitchers, swimmers, etc.)

Question 6

Relationships between Triceps and Teres Muscles

Answer 6

Notice how the long head of the triceps brachii muscle passes posterior (or on top of) to teres major and anterior (or beneath) the teres minor. This relationship can be useful in lab to help distinguish between muscles and define their borders

Question 7

Spaces and Neurovasculature

Answer 7

Crossing of the teres muscles and long head of triceps brachii also creates three bounded spaces. These are important because they transmit neurovascular structures in the upper limb/shoulder

1. Quadrangular Space: axillary nerve and posterior circumflex humeral artery
2. Triceps hiatus: radial nerve and deep artery of the arm
3. Triangular space: circumflex scapular artery

Question 8

Posterior Arm Muscle

Answer 8

Triceps Brachii:

3 heads: long head, medial head and lateral head

Question 9

Posterior Forearm Muscles

Answer 9

Brachioradialis*
Extensor carpi radialis longus
Extensor carpi radialis brevis
Extensor digitorum
Extensor carpi ulnaris
Extensor digiti minimi 

Deep view:
Supinator
Abductor pollicis longus 
Extensor pollicis brevis
Extensor pollicis longus
Extensor Indicis

Question 10

Scapular Anastomoses

Answer 10

Involves: subclavian artery, suprascapular artery, dorsal scapular artery, subscapular artery (and circumflex scapular artery)

Sites of anastomoses: Suprascapular artery with dorsal scapular and subscapular
And the subscapular with the dorsal scapular artery
Point is: the axial artery can be clamped or have an occlusion proximal to the subscapular artery and blood can still reach the arm and forearm

Question 11

Joints of the Upper Limb

Answer 11

Sternoclavicular
Acromioclavicular
Glenohumeral 
Elbow
Radio-ulnar
Radiocarpal
Carpometacarpal
Metacarpophalangeal
Interphalangeal

Question 12

Sternoclavicular Joint

Answer 12

Parts: manubrium, articular disk, Costo-clavicular ligaments, anterior sternoclavicular ligaments

Although not often injured, the importance of the synovial sternoclavicular joint is that it’s the ONLY bone attachment of the upper limb complex to the thorax. It’s so strong (yet very mobile) that it’s more common for forceful trauma to fracture the clavicle than to injury this joint

Question 13

“Shoulder” Joint

Answer 13

Composed of: acromioclavicular joint
Glenohumeral joint
coracoacromial joint
Scapuloclavicular joint

Question 14

Acromioclavicular

Answer 14

Synovial
Upper limb attached to clavicle via the acromion: acromioclavicular ligament
And the coracoid process: coracoclavicular ligament: made up of trapezoid ligament and conoid ligament
Other stuff in the area: coracoacromial ligament

The coracoclavicular ligament stabilizes the acromioclavicular joint, even though it’s not part of the joint itself (it’s “extra-articular” or external to the joint itself)

Question 15

Glenohumeral Joint

Answer 15

Ball-and-socket, synovial joint
It’s very mobile and unstable
It’s stabilized by some ligaments, 1 ring of fibrocartilage, and a variety of muscles
There are a variety of bursae associated with the glenohumeral joint. Bursae contain synovial fluid and help lubricate structures (e.g. Tendons and ligaments) that may move over a bony features
(Need to understand their location)

Question 16

Glenohumeral-stabilizers

Answer 16

Coracoacromial arch: prevents superior movement. Limits abduction of the humerus unless the humerus is rotated laterally

Capsule of the glenohumeral joint: attaches to humerus and glenoid fossa, reinforced by glenoid labrum (fibrocartilage ring around glenoid fossa) and glenohumeral ligaments.
The inferior portion of the glenohumeral ligament is thickened, and is the strongest deterrent to anterior dislocation of the humeral head

Rotator cuff muscles: tonic muscles that stabilize the humeral head and keep it from slipping inferiorly and posteriorly

Question 17

Glenohumeral Joint (cont.)

Answer 17

The tendon of the long head of biceps brachii muscles travels in the intertubercular sulcus and through the glenoid capsule on its path to attach on the supraglenoid tubercle

This tendon is held in place by the: transverse humeral ligament
If this ligament ruptures, the tendon of the long head of biceps brachii can become displaced

Question 18

Glenohumeral Bursae

Answer 18

Subacromial bursa: (aka subdeltoid bursa) facilitates movement of deltoid and supraspinatus muscles

Question 19

Glenohumeral Vasculature

Answer 19

Posterior humeral circumflex artery is the main supply to the glenohumeral joint capsule

*remember this runs posteriorly with the axillary nerve. They appear posteriorly in the quadrangular space

Question 20

Elbow Joint

Answer 20

This synovial joint is actually composed of multiple bony articulations
Vascular-there is no primary blood supply, instead all collateral and recurrent elbow vessels are involved equally
Ligaments of the elbow: ulnar collateral ligament and radial collateral ligament

Question 21

Elbow-bursae

Answer 21

There are olecranon bursae posterior to the ulna (cutaneous), deep to the triceps brachii (subtendinous) and within the triceps brachii tendon (intratendinous)

These bursae protect the triceps brachii and the olecranon process
They can become inflamed due to repetitive use, acute injury, etc.

Question 22

Radio-ulnar joints

Answer 22

There are multiple articulations between the radius and ulna with multiple joint types
The radio-ulnar joints allow supination and pronation
The proximal radio-ulnar joint is stabilized by the angular ligament, which keeps the radial head in place as it rotates during supination/pronation
The radio-ulnar joint is also stabilized by an interosseous ligament (syndesmosis) between the shafts of the bones

Question 23

Radio-Ulnar/Radio-carpal joints

Answer 23

The distal radio-ulnar joint is synovial

The ulna is relatively fixed (distally) and the radius moves around it

The articular disc of the distal radio-ulnar joint unites the radius and ulna

The wrist join is reinforced by radiocarpal ligaments anteriorly and posteriorly

Question 24

Wrist Joint

Answer 24

Actually the radiocarpal joints, in which the radius articulates with the scaphoid and lunate, the articular disc and the triquetrum (the proximal carpal bones except the pisiform)
It’s stabilized by a radial and ulnar collateral ligament and a variety of fibrous ligaments (radiocarpal ligs) difficult to distinguish from one another
Additionally, the intercarpal joints are stabilized by interosseous ligaments
Both the wrist and intercarpal joints are synovial joints

Question 25

1st Carpometacarpal joint

Answer 25

The thumb has a saddle-shaped joint at the carpometacarpal junction, which permits biaxial movement AND circumduction all to about the same degree

There are carpometacarpal ligaments that stabilize this joint, but they are hard to distinguish from other carpometacarpal and intercarpal ligaments

Question 26

Metacarpophalangeal Joints

Answer 26

Metacarpophalangeal joints are condylar in shape, which permits movement in two planes. Flexion and extension AND abduction and abduction is permitted
Extend your fingers and abduct them. Abduction takes place at the metacarpophalangeal joint
Abduction (and abduction) must be limited, so that the proximal phalanx doesn’t “fall off” of the metacarpal

Medial and lateral collateral ligaments restrict abduction at these joints
They’re lax when the digit is extended but taut when the digit is flexed

Question 27

Interphalangeal Joints

Answer 27

Interphalangeal are hinge joints, permitting flexion and extension

The joints are stabilized by medial and lateral collateral ligaments, which further restrict other motions outside of flexion and extension