Chapter 9 - Shoulder Girdle Flashcards
What makes up the shoulder complex?
scapula, clavicle, sternum, humerus, and rib cage
What joints are found the shoulder complex?
SC, AC, GH, Scapulothoracic articulation
What makes up the shoulder girdle?
scapula and clavicle
What makes up the shoulder joint?
scapula and humerus - make up the GH joint
Scapulothoracic articulation
a unit that gathers the SC and AC joints and the junction between the anterior surface of the scapula and the thoracic cage (connected indirectly by the clavicle and several muscles)
Scapula
Triangular-shaped bone located superficially on the posterior side of the thorax and located between ribs 2 and 7
Sternum
Flat bone located in the midline of the ant. thorax
Sternoclavicular joint (SC)
- formed by the articulation between the manubrium of the sternum and the medial end of the clavicle
- synovial joint that provides the shoulder girdle with its only direct attachment to the trunk
Sternoclavicular ligament
connects the clavicle to the sternum on both the anterior (anterior sternoclavicular ligament) and posterior (posterior sternoclavicular ligament) surfaces
Costoclavicular ligament
a short, flat, rhomboid-shaped ligament that connects the inferior clavicle surface to the superior surface of the costal cartilage of the first rib
Interclavicular ligament
located on top of the manubrium, connecting the superior sternal ends of the clavicles
Acromioclavicular joint (AC)
connects the acromion process of the scapula and the lateral (acromion) end of the clavicle
- plane-shaped synovial joint that allows a gliding motion to occur, contributing toward movement in three planes of motion
Acromioclavicular ligaments
Reinforce the AC joint by holding the acromion process to the clavicle which helps prevent dislocation of the clavicle
Coracoclavicular ligament
accessory ligament to the AC joint that provides stability to the joint and allows the scapula to be suspended from the clavicle
Coracoacromion ligament
forms a roof over the head of the humerus and serves as a protective arch, providing support to the head when an upward force is transmitted along the humerus
Scapulothoracic articulation
provides motion necessary for normal function of the scapula
Scapular elevation
scapula moves superior
Scapular depression
scapula moves inferiorly
Scapular protraction
scapula moves away from posterior midline
Scapular retraction
scapula moves back toward the posterior midline
Scapular upward rotation
inferior angle of the scapula rotates up and away from the vertebral column
Scapular downward rotation
Return to the resting anatomical position from upward rotation
Scapular tilt
shoulder joint goes into hyperextension
Scapular winging
vertebral border of the scapula moves away from the rib cage, happening primarily at the AC joint but can also occur at the scapulothoracic articulation
Scapulohumeral rhythm
- movement relationship between the shoulder girdle and the shoulder joint
- first 30 degrees of shoulder joint motion is pure
- after that, for every 2 degrees of shoulder flexion or abduction, the scapula must rotate 1 degree upward
- 2:1 ration
What muscles make up the shoulder girdle?
trapezius, levator scapula, rhomboids, serratus anterior, pectoralis minor
Upper Trapezius origin
occipital bone, nuchal ligament on upper cervical spinous processes
Upper Trapezius insertion
the outer third of clavicle, acromion process
Upper Trapezius action
scapular elevation and upward rotation
Middle Trapezius origin
spinous processes of C7-T3
Middle Trapezius insertion
scapular spine
Middle Trapezius action
scapular retraction
Lower Trapezius origin
spinous processes of middle and lower thoracic vertebrae
Lower Trapezius insertion
base of scapular spine
Lower Trapezius action
scapular depression and upward rotation
Levator Scapulae origin
transverse processes of C1-4
Levator Scapulae insertion
vertebral border of scapula between the superior angle and spine
Levator Scapulae action
scapular elevation and downward rotation
Rhomboid origin
spinous process C7-T5
Rhomboid insertion
vertebral border of scapula between the spine and inferior angle
Rhomboid action
scapular retraction, elevation, downward rotation
Serratus Anterior origin
lateral surface of the upper 8 ribs
Serratus Anterior insertion
vertebral border of the scapula, anterior surface
Pectoralis Minor origin
anterior surface, ribs 3-5
Pectoralis Minor insertion
coracoid process of the scapula
Pectoralis Minor action
scapular depression, protraction, downward rotation, and tilt
Force couple
muscles pulling in different directions to accomplish the same motion
Reverse muscle action
if the insertion is stabilized, the origin will move
Clavicular fractures
account for the most frequently broken bone in children as a result of a fall on the lateral aspect of the shoulder or an outstretched hand
