Lecture 2 Flashcards
(33 cards)
What is the role of posterior axil-appendicular muscles?
- Connect axial skeleton (trunk) to upper appendicular skeleton (upper limb) on the posterior side of the body
- act on the pectoral girdle and/or arm
What are the 3 groups of muscles in the back?
- Extrinsic (superficial) muscles: move upper extremity
- Intermediate Layer: respiratory muscles
- Intrinsic (deep) muscles: move trunk and back
Which are the 4 muscles that act on the pectoral girdle?
- Trapezius
- Levator Scapulae
- Rhomboid Major
- Rhomboid Minor
Where does the trapezius attach? What are its actions? What innervates the muscle? What is its blood supply?
Attach: Midline from occipital to spinous process of T12 vertebrae –> lateral 1/3 clavicle, spine of scapula
Actions:
- Upper portion: elevate and upward rotate scapula
- Middle portion - retract scapula
- Lower portion: depress and downward rotate scapula
Innervation:
-Accessory Nerve (CN XI) *
Blood supply:
-branches of thyrocervical trunk
What happens when the whole trapezius muscle contracts?
- just retraction of scapula
- upper and lower portions cancel each other out
Where does the levator scapulae attach?
Transverse processes of C1-C4 –> superior angle of scapula
Where does the rhomboid minor attach?
Spinous processes of C7-T1 –> medial border of scapula
Where does rhomboid major attach?
Spinous process of T2-T5 vertebrae –> medial border of scapula
What is the action, innervation, and blood supply of the levator scapulae, rhomboid minor, and rhomboid major?
Action: elevate and retract scapula
Innervation: dorsal scapular nerve
Blood supply: dorsal scapular artery (from thyrocervical trunk)
What is the difference in the cross-section of rhomboid minor and rhomboid major?
Rhomboid minor: round
Rhomboid major: flat
Where does the latissimus dorsi act?
on the arm
Where does latissimus dorsi attach? What is its action? What innervates the muscle? What supplies blood?
Attachment: spinous processes of T7-T12 vertebrae, thoracolumbar fascia, iliac crest –> anterior shaft of humerus *
Action: adducts, extends, and medially rotates arm
Innervation: thoracodorsal nerve
Blood supply: thoracodorsal artery
What is the triangle of auscultation? What is its clinical significance?
- No large muscles, good place to listen for respiratory sounds with stethoscope
- inferior: latissimus dorsi
- superior: trapezius
- Lateral:rhomboid major
Where do intrinsic muscles of the shoulder act? Where do they originate?
- Act on the arm at the glenohumeral joint
- Orginate at the scapula
What are the 4 rotator cuff muscles?
-Supraspinatus, infraspinatus, teres minor, subscapularis (SITS)
Where does the supraspinatus attach? What is its action? What nerve innervates it? What blood supply?
Attachment
- Scapula: Supraspinous fossa
- Humerus: Greater tubercle (superior side)
Action: abduction of arm (first 15 degrees)
Nerve: Suprascapular nerve
Blood: Suprascapular artery
Where does the infraspinatus attach? What is its action? What nerve innervates it? What is the blood supply?
Attachment:
- Scapula: Infraspinous fossa
- Humerus: Greater tubercle (lateral side)
Action: Lateral rotation of arm
Nerve: Suprascapular nerve
Blood: Suprascapular and circumflex scapular arteries
Where does the teres minor attach? What is its action? What nerve innervates it? What is the blood supply?
Attachment:
- Scapula: Lateral border
- Humerus: Greater tubercle (lateral side)
Action: Lateral rotation of arm
Nerve: Axillary nerve
Blood: Circumflex scapular and posterior circumflex humeral arteries
Where does the subscapularis attach? What is its action? What nerve innervates it? What is the blood supply?
Attachment:
- Scapula: Subscapular fossa
- Humerus: Lesser tubercle *
Action: Medial rotation of arm
Nerve: Upper and lower subscapular nerves
Blood: Subscapular artery
What is a typical rotator cuff tear?
- Typically a tear in the supraspinatus
- due to overuse
Where does the teres major attach? What is its action? What nerve innervates it? What is the blood supply?
Attachment:
- Scapula: inferior angle
- Humerus: anterior humeral shaft
Action: medial rotation of arm
Nerve: Lower sub scapular nerve
Blood: Circumflex scapular and subscapular arteries
Differentiate teres major from teres minor.
- Only thing in common is both have round (terse) cross sections
- Teres Major: synergist of latissimus dorsi, both medially rotate the arm
- Teres minor: synergist of infraspinatus, both act to laterally rotate the arm
Where does the deltoid attach? What is its action? What nerve innervates it? What is the blood supply?
Attachment:
- Scapula: spine and acromion
- Clavicle: lateral 1/3
- Humerus: deltoid tuberosity * (deltoid tuberosity often tagged in lab according to prof)
Action:
- Anterior (clavicular): flexes and medially rotates arm
- Middle (acromial): abduct arm (15-90 degrees) * primary role is of powerful abductor
- Posterior (spinal): extends and laterally rotates arm
Nerve: Axillary nerve
Blood: Thoracoacromial artery, anterior and posterior humeral circumflex arteries
Explain arm abduction. What is the ratio of scapular/humeral movement?
- First 15 degrees: supraspinatus
- 15-90 degrees: deltoid
- must rotate scapula to raise arm about 90 degrees, using trapezius and serrates anterior
- adduction involves coordinated muscle actions in 1:2 scapular/humeral ratio (both move concurrently)
