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60 Cards in this Set

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  • Back
What are the skeletal components of the pectoral girdle?
Clavicle + Scapula
What is the function of the pectoral girdle?
-Attaches upper limb to trunk
-Support base (mobile OR fixed) for limb motions
-Shock absorber
-Protects neurovascular structures passing through axilla from neck
How does the pect. girdle act as a shock absorber?
It transfers force from the upper limb to the trunk.
what is the most commonly fraactured bone in the body?
Clavicle - at the outer (lateral) 1/3
What does the clavicle do?
1. Acts as a rotatable strut to keep the limb away from the trunk.
2. Transmits weight of upper limb to trunk
3. Bony attchmt for muscles
What does the humerus articulate with?
The scapula - only by muscles
What rami innervate the shoulder muscles?
All are ventral rami innervated
What are the 4 muscle groups affecting shoulder movement?
1. Trapezius
2. Latissimus Dorsi
3. Levator Scapulae
4. Rhomboids
3 functions of trapezius:
1. Suspends upper limb
2. Controls scapular descent
3. Squaring of the shoulder
What are the 3 components of the trapezius?
1. Superior fibers
2. Middle fibers
3. Inferior fibers
What is trapezius innervated by?
CN 11, C3-C4
What is the action of the superior fibers of trapezius?
-Scapular elevation
-Upward rotation
What is the action of the middle fibers of trapezius?
Scapular retraction
What are the actions of the inferior fibers?
Scapular depression
Upward rotation
What innervates the Latissimus Dorsi?
Thoracodorsal nerve (C6-C8)
What innervates levator scapulae?
Dorsal scapular (C3-C5)
What innervates the rhomboids?
dorsal scapular nerve(C5)
What are the actions of the latissimus dorsi?
Extension, Adduction, and Medial Rotation of the Humerus.
What are the actions of Levator Scapulae?
Scapular elevation (duh) and inferior rotation of the glenoid fossa.
What are the actions of the Rhomboids?
Scapular retraction, elevation, fixation (of its medial border), and inferior rotation.
What are the muscles passing from the thoracic wall to the pectoral girdle or humerus?
1. Pectorals (major/minor)
2. Serratus Anterior
What innervates the pecs?
Medial and Lateral Pectoral Nerves (from Lat/Med CORDS, C5-T1)
What innervates Serratus Anterior?
Roses are red, violets are blue, the Long Thoracic Nerve goes to Serratus Anterior.
(C5-C7 - branch of ROOTS)
What are the actions of the Pectorals?
1. Humerus: Adduction, Medial rotation, and Flexion (when adducting).
2. Scapula: Depress/Protract
What are the actions of Serratus Anterior?
1. Scapular protraction, fixation, and rotation.
What is the origin/insertion of Serratus Anterior?
Origin: Ribs 1-9
Insertion: Vertebral border and inferior angle of scapula
What is a Winged Scapula?
Dorsal protrusion (out the back) of the scapula's inferior angle - your chicken bone sticks out without you trying.
How would you know your winged scapula is caused by injury to the long thoracic nerve (to serratus anterior)?
If winging occurs while the arm is flexed and dorsal pressure is applied.
How would you know your winged scapula is caused by injury to the nerve to the Trapezius (CN11, C3-C4)?
If winging occurs while arm is abducted.
What 6 muscles pass from the pectoral girdle to the humerus?
1. Deltoid
2. Supraspinatus
3. Infraspinatus
4. Teres minor
5. Teres major
6. Subscapularis
What innervates the deltoid?
Axillary nerve - C5-C6
So what does the axillary nerve innervate?
Teres minor + Deltoid muscle
What motions are achieved by the deltoid's:
-Anterior portion
-Middle portion
-Posterior portion
Anterior: flexion and medial rotation of the humerus
Middle: humeral abduction
Posterior: extension and lateral rotation of humerus
Is the deltoid responsible for all the abduction of the ul?
No; first 10 degrees is done by supraspinatus.
Speaking of that, what innervates supraspinatus? What else does this innervate?
Suprascapular nerve (C5-C6)
-Also infraspinatus
What motion does Supraspinatus achieve?
Humeral abduction, flexion, and stability
What motion does infraspinatus achieve?
Humeral lateral rotation, and stability in extension.
What innervates:
-Teres minor
-Teres major
Minor = axillary nerve
Major = subscapular nerve
What all does the subscapular nerve innervate?
-Teres major
What are the motions of Teres minor?
Same as infraspinatus:
-Humeral lateral rotation (in abduction)
-Stability in extension
What are the motions of Teres major?
Humeral adduction
Medial rotation
Extension from flexed position.
What causes Teres major to lose its power?
If humeral extension went beyond its origin.
What innervates Teres major?
What 2 muscles does the Subscapular nerve innervate?
-Teres major
What are the motions of Subscapularis?
-Primary humeral medial rotation
What 4 muscles make up the rotator cuff?
-Teres minor
What innervates all of the muscles passing from the pectoral girdle -> humerus?
Which 2 nerves are the oddballs in the previous statement?
Subscapular nerve
-To teres major = C6-C7
-To subscapularis = C5-C7
What is the main responsibility of the rotator cuff?
To stabilize the glenohumeral joint.
What stabilizes the inferior part of the glenohumeral joint?
The triceps longhead.
What is the scapulothoracic articulation?
Where the scapula interacts with the posterior wall of the thorax. (chicken bone + back)
What movements occur at the scapulothoracic articulation?
-Upward/downward rotation
What 4 muscles cause Elevation of the scapula?
Trapezius (upper fibers)
Levator Scapulae
Rhomboids (major/minor)
What 6 muscles cause Depression of the scapula?
-Pec minor
-Trapezius (lower fibers)
-Serratus anterior
-Latissimus dorsi
-Pectoralis major (indirectly via sternocostal head)
What are the prime movers that cause depression?
The first three:
Pec minor, Lower Trapezius, Serratus anterior
What 2 muscles cause Upward rotation of the scapula? when?
-Trapezius (upper/lower) during limb abduction
-Serratus anterior (lower) during limb flexion
What 4 muscles cause downward rotation of the scapula?
-Rhomboid major
-Levator scapulae
-Pec minor
-Pec major - sternocostal head
What 3 muscles cause protraction of the scapula?
Serratus anterior
Pec minor
Pec major (sternocostal head)
What 4 muscles cause retraction of the scapula?
Trapezius (mid/lower fibers)
Rhomboid major
Rhomboid minor
Latissimus dorsi
What is the PURPOSE of moving the scapula on the posterior thoracic wall????
Positioning of the glenoid fossa.