Lecture 5
What is the shoulder complex?
the shoulder complex is the shoulder girdle and shoulder joint.
- scapula, clavicle, sternum, humerus, rib cage
- sternoclavicular, acromiclavicular, glenohumeral joints
- scapulothoracic articulation
What is the function of the scapula?
-orient the glenoid fossa for maximal use of upper extremities
- provide a stable base for ball and socket movements of glenohumeral joint
- scapula and glenohumeral joint are always discussed together
(lots of mobility less stability, it is an articulation not a real joint)
What is the steernoclavicular joint?
- plane synovial joint: three degrees of freedom
- 3 major ligaments and joint disk
- anterior and posterior sternoclavicular ligaments reinforce joint capsule
- costoclavicular ligament: located between first rib and clavicle
- interclavicular ligament: runs from the sternal end of one clavicle to the sternal end of the other
What is the acromioclavicular joint?
-primarily maintains relationship between the scapula and clavicle
- identified as a gliding or plane joint; 3 degrees of freedom
- produces longitudinal rotation of clavicle necessary for full ROM and elevation of upper extremity
- ligaments:
- superior and inferior acromioclavicular ligaments: maintain relationship between clavicle and scapula
- coracoclavicular ligament: provides stability; prevents superior dislocation of clavicle
- coracoacromial ligament: provides support to head of humerus
What is the position of the scapula?
What plane is the scapula in?
-scapula rests at a 30 degree angle from the frontal plane to the rib cage (due to its curves)
- scaption: elevation of the arm in the plane of the scapula (between flexion and abduction)
What is scapulothoracic articulation?
-not a true anatomic joint (does not have true characteristics)
- maintains a direct relationship of scapula to the thorax
- moving away from midline in upward reach
What is the glenohumeral joint?
What are the ligaments of the GH joint?
- articulation of head of humerus and glenoid fossa, glenoid fossa, glenoid labrum, joint capsule of glenohumeral joint
- 3 ligaments reinforce capsule
- coracohumeral ligament: passive support of UE versus gravity
- coracoacromial arch: acromion + coracoacromial ligament... prevents superior dislocation
What are the scapular movements?
-elevation/ depression
- abduction/ protraction
- adduction/ retraction
- upward rotation
- downward rotation
- upward lift/ lateral tilt
What is scapular tilt?
- occurs with hyperextension of the shoulder
- inferior angle tilts posteriorly, away from the thorax
- when arms are behind us the scapula tilts
What is scapulohumeral rhythm?
- humerus must coordinate with the scapula to provide smooth, full range of motion without impingement
- 180 degrees of shoulder flexion/ abduction=
- 120 degrees of glenohumeral motion
- 60 degrees of scapulothoracic motion
What is the purpose of scapulohumeral rhythm?
- maintain glenoid fossa in optimal position to receive head of humerus
- increase joint congruency and decrease shear forces
- distributes motion between two joints permitting a larger ROM with more stability
- [ermits muscles acting on humerus to maintain a good length tension relationship
What are the clinical implications?
- shoulder cannot fully flex/ abduct without scapulothoracic motion
- attempting ROM without movement at ST articulation will cause damage
- damage at sternoclavicular ligament/ joint
--> clavicle cannot elevate--> limited shoulder motion
- damage at coroclavicular ligament
--> clavicle will not rotate --> limited shoulder motion
What are the muscles of the scapula/ shoulder?
- serrates anterior
- pectoralis minor
- upper trap
- middle trap
- lower trap
- rhomboids
- levator scapulae
What is scapular winging?
Some people's scapulas will pop out posteriorly which is winging
What is a linear force system?
Linear force systems: 2 or more forces act upon an object in the same line
- ex:soleus muscle and gastrocnemius muscle
What is a parallel force system?
Parallel force system is when 2 or more parallel forces act on the same object in the same plane and in the same or opposite direction
- example: abdominals and extensors on the trunk
What are concurrent force systems?
concurrent force systems are 2 or more forces that act at a common point of application but in divergent directions
Example: pecs in action
- clavicular portion of pectorals major, sternalportion of pectorals major, pectorals major both parts
why are force couples?
Force couples are when two or more forces act with neutralizing force in different in different directions resulting in a turning effect
- example: upward rotation of scapula, downward rotation of scapular
Do the lab again
I don't like lab though
how is your day
not good I hate Kines
How are we feeling?
strong about the exam
Will we pass tomorrow?
Conner is annoying me anyone else?
yes everyone, good I kicked him out
Are you hungry?
yes I am hungry
LETS ACE THI EXAM
goodbye everyone please leave while I cry