Shoulder, Posterior Arm And Forearm, And Joints Flashcards
Superficial Back Muscles
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
Shoulder-Deltoid
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
Anterior Shoulder Muscles
Supraspinatous
Subscapularis
Posterior Shoulder Muscles
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)
Rotator Cuff Muscles
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.)
Relationships between Triceps and Teres Muscles
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
Spaces and Neurovasculature
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
- Quadrangular Space: axillary nerve and posterior circumflex humeral artery
- Triceps hiatus: radial nerve and deep artery of the arm
- Triangular space: circumflex scapular artery
Posterior Arm Muscle
Triceps Brachii:
3 heads: long head, medial head and lateral head
Posterior Forearm Muscles
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
Scapular Anastomoses
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
Joints of the Upper Limb
Sternoclavicular Acromioclavicular Glenohumeral Elbow Radio-ulnar Radiocarpal Carpometacarpal Metacarpophalangeal Interphalangeal
Sternoclavicular Joint
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
“Shoulder” Joint
Composed of: acromioclavicular joint
Glenohumeral joint
coracoacromial joint
Scapuloclavicular joint
Acromioclavicular
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)
Glenohumeral Joint
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)
Glenohumeral-stabilizers
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
Glenohumeral Joint (cont.)
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
Glenohumeral Bursae
Subacromial bursa: (aka subdeltoid bursa) facilitates movement of deltoid and supraspinatus muscles
Glenohumeral Vasculature
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
Elbow Joint
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
Elbow-bursae
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.
Radio-ulnar joints
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
Radio-Ulnar/Radio-carpal joints
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
Wrist Joint
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
1st Carpometacarpal joint
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
Metacarpophalangeal Joints
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
Interphalangeal Joints
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
