ANAT337-L Pectoral Girdle & Arm

Pectoral girdle

includes clavicle and scapula; articulates with the trunk and serves to support the upper limb

Clavicle

S shaped bone that articulates medially with sternum and laterally with acromion

Sternoclavicular joint

super stable saddle joint between manubrium and sternal end of these two bones

contains a fibrocartilage disc; only articular capsule attaching arm to body

movements include elevation, depression, protraction, retraction and posterior rotation

Rarer but has the potential to damage important neurovasculature like subclavian artery

Why is a posterior clavicle fracture potentially life threatening?

Scapula

broad, flat, triangular bone that overlies ribs 2-7 of back thoracic cage

Glenoid fossa

socket of GH ball and socket; more dish shaped in its size and shallowness

Scapulothoracic joint

functional joint (no capsule/articulation) between the ventral surface of the scapula and the posterior thoracic wall

requires movement from AC/SC joints

Acromioclavicular joint

plane joint between scapula and acromial end clavicle that contains a fibrocartilage disc and two distinct ligaments

AC joint sprain

there are many grades of this sprain, the most severe of which results in a complete tearing of the ligaments that stabilize it and a characteristic “drop shoulder”

Sprained; strained

Ligaments are ___, muscles are ___.

Glenohumeral joint

ball and socket joint between humerus and scapula

most freely mobile joint in the human body

Glenoid labrum

fibrocartilaginous rim of scapula fossa that helps with the instability of the GH joint by deepening the socket

Anteriorly and inferiorly (when arm is extended and abducted)

In what direction does shoulder dislocation usually occur?

Scapulohumeral rhythm

when limb reaches 180 degree abduction ⅔ of that movement comes from the GH joint, and the other ⅓ comes from the SC joint (scapula’s rotation upwards)

8

How many carpal bones are in wrist?

5

How many metacarpal bones are there?

14

How many phalanges in fingers?

trapezius, levator scapulae, rhomboid minor, rhomboid major, pectoralis minor, serratus anterior, subclavius

Muscles that stabilize the scapula

latissimus dorsi, pectoralis major, deltoid, coracobrachialis, teres major, rotator cuff muscles, triceps brachii, biceps brachii

Muscles that insert on the humerus and cause movement of the arm

• Anterior circumflex humeral artery

• posterior circumflex humeral artery

• axillary nerve

The surgical neck of the humerus is the location of these three vessels.

Levator scapulae

• actions: elevates and superiorly rotates scapula

• insertion: superior medial border of scapula

• innervation: dorsal scapular nerve

• blood supply: dorsal scapular artery

Rhomboid minor

• actions: elevates, retracts, and inferiorly rotates scapula

• insertion: medial border of scapula

• innervation: dorsal scapular nerve

• blood supply: dorsal scapular artery

Rhomboid major

• actions: elevates, retracts, and inferiorly rotates scapula

• insertion: superior medial border of scapula

• innervation: dorsal scapular nerve

• blood supply: dorsal scapular artery

Trapezius (superior fibers)

• actions: elevate and superiorly rotate scapula

• innervation: CN XI

• blood supply: dorsal scapular artery

Trapezius (middle fibers)

• actions: retract scapula

• innervation: CN XI

• blood supply: dorsal scapular artery

Trapezius (inferior fibers)

• actions: depress scapula

• innervation: CN XI

• blood supply: dorsal scapular artery

Deltoid (anterior fibers)

• actions: flex and medially rotate GH joint

• insertion: deltoid tuberosity of humerus

• innervation: axillary nerve

Deltoid (middle fibers)

• actions: GH abduction

• insertion: deltoid tuberosity of humerus

• innervation: axillary nerve

Deltoid (posterior fibers)

• actions: extend and laterally rotate GH joint

• insertion: deltoid tuberosity of humerus

• innervation: axillary nerve

Teres major

• actions: extends, adducts, and medially rotates GH joint

• origin: inferior lateral border and inferior angle of scapula

• insertion: lesser tubercle and intertubercular groove of humerus

• innervation: lower subscapular nerve

Latissimus dorsi

• actions: extends, adducts, and medially rotates GH joint

• insertion: intertubercular groove of humerus

• innervation: thoracodorsal nerve

• blood supply: thoracodorsal artery

Pectoralis major

• actions: arm flexion, adducts and medially rotates GH joint

• insertion: intertubercular groove of humerus

• innervation: lateral and medial pectoral nerves

Serratus anterior

• actions: protracts and superiorly rotates scapula, stabilizes scapula

• insertion: anterior medial border of scapula

• innervation: long thoracic nerve

• blood supply: lateral thoracic artery

Coracobrachialis

• actions: adducts and flexes GH joint

• origin: coracoid process

• insertion: middle medial shaft of humerus

• innervation: musculocutaneous nerve

Pectoralis minor

• actions: protracts and depresses scapula

• insertion: coracoid process of scapula

• innervation: medial pectoral nerve

Subclavius

• actions: stabilizes and depresses clavicle

• innervation: nerve to the ___