Shoulder and Scapular Region Flashcards
What bones comprise the pectoral girdle?
- Scapula (shoulder blade)
- Clavicle (collarbone)
Define Articulation
- Place where two or more bone meet
- Can be immovable, slightly moveable or freely moveable
Synovial Joint
- Freely Moveable
- Surrounded by a joint capsule
- Contains synovial fluid that lubricates the bone ends
Describe the relationship between stability and mobility of joints. Define close pack and loose pack positioning.
- Inverse relationship
- Close Pack:
- Position of greatest stability (least mobility) of a joint
- Ligaments are taught, bones in greatest contact
- Loose Pack:
- Position of greatest mobility (least stability)
- Ligaments are lax, less contact between bones
Hilton’s Law
- Nerves supplying a joint also supply the muscles moving the joint and skin covering insertion of muscles
“O’Loughlin’s Law”
- If a muscle crosses a joint, it must move that joint
Shoulder Joint
- Consists of three joints:
- Sternoclavicular Joint
- Acromioclavicular Joint
- Glenohumeral Joint (shoulder joint proper)
- Very mobile (relatively unstable)
Sternoclavicular Joint
- Joint between clavicle and sternum (manubrium)
-
Strong, Stable Joint (reinforced by many ligaments)
- Rarely dislocates
Acromioclavicular Joint
- Synovial joint between acromion and lateral end of clavicle
- Stabilized superiorly by the acromioclavicular ligament
- Lateral part of clavicle attached to coracoid process by coracoclavicular ligament
Shoulder Separation
-
Dislocation of acromioclavicular joint
- Graded on Severity:
- Type 1: mild sprain
- Type 2: subluxation of joint (partial dislocation)
- Type 3: complete dislocation and tear of cracoclavicular ligament
- Graded on Severity:
Symptoms:
- Pain when arm is aBducted more than 90 degrees
- Tenderness and edema
- Acromion prominent (sticks laterally) and superior movement of clavicle
Glenohumeral Joint
“Shoulder Joint Proper”
-
Ball and socket synovial joint
- Between head of humerus and scapula
-
Most mobile joint in body (most unstable)
- Most frequently dislocated
- Stability comes from rotator cuff muscles
Structure:
- Thin capsule
- Several bursae (synovial fluid filled sacs)
- Located where tendons rub against bone/ligaments or where skin moves over bony (areas of friction)
- Inflammation leads to bursitis
Shoulder Dislocation
- Dislocation of glenohumeral joint
- Inferior, anterior movement of humerus
- Unable to move joint (difference from shoulder separation)
Deltoid Region
- Skin of posterior shoulder innervated by posterior rami
- Skin of lateral/anterior shoulder innervated by anterior rami
What are the extrinsic muscles of the shoulder?
- Superficial Back Muscles
What are the intrinsic muscles of the shoulder? Why are they called intrinsic?
-
Muscles that both originate and insert on upper limb
- Deltoid
- Teres Major
- Rotator Cuff Muscles
Deltoid
Innervation:
- Axillary n. (Brachial Plexus; C5-C6)
Insertion:
- Deltoid tuberosity of humerus
Action:
- Primary aBductor of upper limb
Blood Supply:
- Posterior circumflex humeral a.
Teres Major
Innervation:
- Lower subscapular n.
Origin:
- Inferior angle of scapula
Insertion:
- Intertubercular sulcus of humerus
Action:
- Extends, adducts and medially rotates humerus
Blood Supply:
- Circumflex scapular a.
Which muscles comprise the rotator cuff?
- Subscapularis
- Supraspinatus
- Infraspinatus
- Teres Minor
Subscapularis
Innervation
- Subscapular nn. (Upper and Lower)
Origin:
- Subscapular fossa
Insertion:
- Lesser tubercle of humerus
Action:
- Medially rotate arm
Blood Supply:
- Subscapular a.
Supraspinatus
Innervation:
- Suprascapular n. (Brachial Plexus; Superior Trunk)
Origin:
- Supraspinous fossa
Insertion:
- Greater tubercle of humerus
Action:
- ABduct arm
Blood Supply:
- Suprascapular a.
Infraspinatus
Innervation:
- Suprascapular n.
Origin:
- Infraspinous fossa
Insertion:
- Greater tubercle of the humerus
Action:
- Adduct and laterally rotates arm
Blood Supply:
- Suprascapular a.
Teres Minor
Innervation:
- Axillary n.
Origin:
- Lateral border of scapula
Insertion:
- Inferior greater tubercle
Action:
- Adduct and laterally rotates arm
Blood Supply:
- Circumflex scapular a.
Triangular Space Contents and Borders
- Circumflex Scapular a.
- Borders:
- Teres Major
- Teres Minor
Quadrangular Space Contents and Borders
- Axillary Nerve
- Posterior Humeral Circumflex a.
- Borders:
- Teres Minor
- Teres Major
- Long Head Triceps Brachii
- Humerus
Triceps Hiatus Contents and Borders
- Radial n.
- Deep Brachial a.
- Borders:
- Triceps brachii
- Humerus
- Teres Major
Arterial Supply to Upper Limb
-
Subclavian a.
-
At lateral border of first rib renamed axillary a.
- At inferior border of teres major renamed brachial a.
-
At lateral border of first rib renamed axillary a.
Venous Drainage of Upper Limb
- Deep veins have same names as arteries
- Superficial veins:
- Cephalic Vein: on preaxial border (thumb side)
- Basilic Vein: on postaxial border (pinky side)
- Median cubital vein: location of venipuncture
