Ch. 8 Pectoral Gridle Flashcards
Skeleton of Upper Limb
- each upper limb has 32 bones
- form pectoral girdle and free part
Pectoral Girdle- Clavical
- convex in shape anteriorly near the sternal junction
- clavicle is concave anteriorly on its lateral edge near the acromion
- it is S shaped
- medial end articulates with the manubrium of the sternum forming the sternoclavicular joint
- lateral end articulates with the acromion forming the acromioclavicular joint
- acrominal end articulates with acromion of the scapula
- a coniod tubercle and impression for the costoclavicular ligament serve as attachments for ligaments
Pectoral Girdle- Scapula
- shoulder blade, triangular in shape
- spine: large process on the posterior of the scapula that ends laterally as the acromion (splits into two)
- acromion: flattened lateral portion of the spine of the scapula
- coracoid process: a protuding projection on the anterior surface just inferior to the lateral aspect of the clavicle that tendons of muscle attach to
- glenoid cavity: shallow concavity that articulates with the head of the humerus to form the glenohumeral joint
Appendicular Skeleton
- primary function is movement
- includes bones of the upper and lower limbs
- girdles attach the limbs to the axial skeleton
- girdles of bones that attach the upper and lower limbs to the axial skeleton:
- pectoral girdle consists of bones that hold upper limbs in place
- pelvic girdle consists of bones that hold lower limbs
- pelvic girdle is adaptive for various movements and muscle attachments
free part of upper= (clavicle, scapula, humerus, radius, ulna, carpals, metacarpals, phalanges)
Medial (vertebral) border
closest to the vertebral spine
Lateral Border
closest to the arm, thick edge
Superior Border
superior edge, joins vertebral border at superior angle
Inferior Angle
where medial and lateral borders meet inferiorly
Superior Angle
uppermost aspect of scapula where medial border meets superior border
Subscapular Fossa
anterior concavity where the subscapularis muscle attaches
Supraspinous Fossa
posterior concavity superior to the scapular spine, attachment site for supraspinatus muscle
Infraspinous Fossa
Posterior concavity inferior to the scapular spine, site of infraspinatus muscle (shoulder)
Shoulder Joint
- ball and socket joint formed by the head of the humerus and the glenoid cavity of the scapula
- articular cartilage
- coracohumeral, glenohumeral, transverse humeral ligaments
- glenoid labrum
- bursae
- flexion/extension, abduction/adduction, circumdation
Muscles that Move the Pectoral Girdle
- stabilizing the scapula so it can function as a stable origin for the muscles that move that humerus
- scapular movements increase the range of motion of the humerus
- many humeral movements would not be possible without scapular movements accompanying those of the humerus
- muscles work in groups that are either synergistic or antagonistic
Movements by muscles at the Scapula
- protraction, retraction, elevation, depression, superior rotation, inferior rotation
Anterior Thoracic Muscles
Serratus Anterior: abducts scapula and rotates it upward
Pectoralis Minor: abducts scapula and rotates it downward
Subclavius: depresses and moves clavicle anteriorly and helps stabilize pectoral girdle
Posterior Group Thoracic Muscles
Trapezius: superior rotate scapula, middle adduct, inferior depress, upward rotate
Levator Scapulae: elevates scapula and rotates it downward
Rhomboideus: elevates and adducts, stabilizes scapula, major- downward, minor- upward
Scapular Notch
bring blood vessels to pectoral girdle
Subclavius
- anterior thoracic muscle
- rib 1
- clavicle
- depresses and moves clavicle anteriorly and helps stabilize pectoral girdle
Pectoralis Minor
- ribs 2-5
- coracoid process of scapula
- abducts scapula and rotates it downward
Serratus Anterior
- ribs 1-8 or 1-9
- Vertebral border and inferior angle of scapula
- abducts scapula and rotates it upward
Trapezius
- superior nuchal line of occipital lobe, ligamentum nuchae, and spines of C7-T12
- clavicle and acromion and spine of scapula
- superior fibers upward rotate scapula; middle fibers adduct scapula; inferior fibers depress and upward rotate scapula; superior and inferior fibers together rotate scapula upward, stabilizes scapula
Levator Scapulae
- transverse processes
- superior vertebral border of scapula
- elevates scapula and rotates it downward
Rhomboid Major
- spines of T12-T5
- vertebral border of scapula inferior to spine
- elevates and adducts scapula and rotates it downward; stabilizes scapula
Rhomboid Minor
- spines of C7-T1
- vertebral border of scapula superior to spine
- elevates and adducts scapula and rotates it downward; stabilizes scapula
Pectoralis Major
- clavicle, sternum, and costal cartilages of ribs 2-6 and sometimes of ribs 1-7
- greater tubercle and lateral lip of the intertubercular sulcus of humerus
- as a whole, adduct and medially rotates arm at shoulder joint, clavicular head flexes arm, and sternocostal head extends the flexed arm to side of trunk
Latissimus Dorsi
- spines of T7-L5, crests of sacrum and ilium, ribs 9-12
- intertubercular sulcus of humerus
- extends, adducts, and medially rotates arm at shoulder joint; draws arms arm inferiorly and posteriorly
Scapular Muscles the Move the Humerus
- Deltoid
- Subscapularis
- Supraspinatus
- Infraspinatus
- Teres Major
- Teres Minor
- Coracobrachialis
