Week 6 Flashcards
What kind of joint is the shoulder joint?
Ball and socket joint
Characteristics of the shoulder joint
- one of the most mobile yet unstable joints in the body
- Movement in 3 planes
Sagittal, frontal, transverse
3 degrees of freedom
What is the function of the rotator cuff?
- Helps to rotate the shoulder against the glenoid fossa during shoulder motion
- Stabilize the head of humerus during shoulder joint motion
True or false: the rotator cuff is more a generator of rotation than a facilitator of rotation
False
More facilitators of rotation as opposed to generators of rotation
What is the origin of the anterior deltoid?
Lateral 1/3 of clavicle
What is the insertion of the anterior deltoid?
Deltoid tuberosity
What is the action that the anterior deltoid performs?
- Abduction
- Flexion
- Medial rotation
- Horizontal adduction
What are some characteristics/functions of the anterior deltoid
Front portion of deltoid fibres
Deltoid is its own antagonist
What is the origin of the middle deltoid?
Acromion process
What is the insertion of the middle deltoid?
Deltoid tuberosity
What action does the middle deltoid perform?
Abduction
What is the origin of the posterior deltoid?
Spine of scapula
What is the insertion of the posterior deltoid?
Deltoid tuberosity
What action does the posterior deltoid perform?
- Abduction
- Extension
- Hyperextension
- Lateral rotation
What are some characteristics/functions of the posterior deltoid?
- Back portion of deltoid fibres
-Runs on a diagonal (obliquely)
What is the origin of the pectoralis major?
Medial 1/3 clavicle
Sternum
Costal cartilage of ribs 1-6
What is the insertion of the pectoralis major?
Bicipital groove (lateral lip)
What action does the pectoralis major perform?
Shoulder flexion (first 60 degrees)
-Shoulder extension (first 60 degrees)
-Adduction
- Medial rotation
-Horizontal adduction
What is the origin of the latissimus dorsi?
- Spinous process of T7-L5
- posterior sacrum
- iliac crest
- lower 3 ribs
What is the insertion of the latissimus dorsi?
Bicipital groove
What action does the latissimus dorsi perform?
- Shoulder extension
- Adduction
- Medial rotation
- Hyperextension*
What are some characteristics/functions of the latissimus dorsi?
Broad, sheet-like muscle
Superficial
What is the origin of the teres major?
Inferior lateral border of scapula
What is the insertion of the teres major?
Bicipital groove, below lst tubercle under latissimus dorsi
What action does the teres major perform?
Extension, adduction, and medial rotation
What are some characteristics/functions of the teres major?
- Follows latissimus dorsi to humerus
Nicknamed as latissimus dorsi’s little helper
What are the rotator cuff muscles?
SITS muscle
S - supraspinatus
I - infraspinatus
T – teres minor
S – subscapularis
What is the origin of the supraspinatus?
Supraspinous fossa
What is the insertion of the supraspinatus?
Greater tubercle
What action does the supraspinatus perform?
Abduction and stabilizes shoulder
What are some characteristics/functions of the supraspinatus?
Above the spine
Passes underneath acromion to its insertion
doesn’t generate rotation
Initiates abduction (helps it get started before deltoid takes over)
All rotator cuff muscles are weak
What is the origin of the infraspinatus?
Infraspinous fossa
What is the insertion of the infraspinatus?
Greater tubercle
What action does the infraspinatus perform?
lateral rotation and horizontal abduction
What is the origin of the teres minor?
Lateral border of scapula
What is the insertion of the teres minor?
Greater tubercle
What action does the teres minor perform?
lateral rotation and horizontal abduction
What are some characteristics/functions of the teres minor?
Very similar to infraspinatus
Attaches to back part of humerus just below infraspinatus
What is the origin of the subscapularis?
Subscapular fossa
What is the insertion of the subscapularis?
Lesser tubercle
What action does the subscapularis perform?
Medial rotation of humerus
What are some characteristics/functions of the subscapularis?
Starts out on the anterior side of the scapula
Horizontal line of pull –> prime mover for medial rotation as it inserts on lesser tubercle
What is the origin of the coracobrachialis?
coracoid process
What is the insertion of the coracobrachialis?
medial humerus halfway down
What action does the coracobrachilais perform?
Stabilizes shoulder
Assists in flexion
What are some characteristics/functions of the coracobrachialis?
Weak flexor
Vertical line of pull
What is the difference between a first class, second class, and third class lever?
First class lever: has the fulcrum in the middle
Second class lever: have the load in the middle
Third class lever: has the effort in the middle
Levers: refer to a bone
Fulcrum: refers to the joint that is formed by the connection between two or more bones.
Effort: refers to the force generated by the contraction of the muscles in the lever system
What is the most popular type of lever in the body?
Third class levers
What is a force arm?
the distance between the point where the force or effort is applied and the axis. Also called moment arm
What is a resistance arm?
the distance between the point where the resistance or load is applied and the axis.
What is a joint capsule made of?
- Thin wall
- Outer fibrous membrane
- Inner synovial membrane
- Attaches around rim of glenoid fossa and anatomical neck of humerus
