Lecture 29 Shoulder Flashcards
What does the brachial plexus consist of?
- ventral rami of C5, C6, C7, C8, T1
what provides the motor innervation to the trapezius?
- CN11
What provides the sensory innervation to the trapezius?
- C3 and 4
What innervates the latissimus dorsi?
- thoracodorsal nerve
What makes up layer one of posterio axio appendicular muscles?
- trapezius and latissimus dorsi
What makes up layer 2 of posterio axio appendicular muscles?
- levator scapulae
- rhomboid minor
- rhomboid major
What makes up layer 3 of posterior axio-appendicular muscles
- serratus posterior superior and inferior
what nerve innerates the rhomboid major and minor?
- dorsal scapular nerve
What nerves innervate levator scapulae?
- 3rd and 4th cervical spinal nerves and dorsal scapular nerve
What is the proximal attachment of the trapezius?
- external occipital protuberance of skull, nuchal ligament, spinous processes of C7-T12 vertebrae
What is the distal attachment of the trapezius?
- lateral third of clavicle (anterior), acromion, and spine of scapula
What is the function of the trapezius?
- elevates, depresses, and retracts scapula, rotates glenoid fossa superiorly
What is the motor innervation of the trapezius?
- CN 11
What is the sensory innervation of trapezius?
- C3 and C4
Where is the anterior attachment of trapezius?
- lateral 1/3 of clavicle
What is the posterior attachment of trapezius?
- spine and acromion of scapula
what movements can the trapezius facilitate on the scapula?
- elevation/depression
- retraction
- upward rotation
What is the proximal attachment of the latissimus dorsi?
- spinous processes of inferior 6 thoracic vertebrae, thoracolumbar fascia, iliac crest and inferior 3 ribs
What is the distal attachment of the latissimus dorsi?
- floor of intertubercular sulcus (bicipital groove) of humerus
_____ muscle extends, adducts, and medially rotates the humerus; raises torso towards arms during climbing
- latissimus dorsi
What innervates the latissimus dorsi?
- thoracodorsal nerve (from brahcial plexus)
What are the actions of the latissimus dorsi on the arm?
- extends humerus
- adducts humerus
- medially rotates humerus
How does the latissimus dorsi act during a pull up?
- raises torso towards arms when climbinh or doing a pull up (raises or pulls torso up when hands/arm is fixed)
What does the latissimus dorsi do when the torso is fixed?
- pulls humerus down
Where is the origin of rhomboid major and minor?
- spinous process of C7-T5
Where is the proximal attachment/origin of rhomboid major?
- T2-T5
Where is the proximal attachment/origin of rhomboid minor?
- C7-T1
- nuchal ligament
Where is the distal attachment of r. major?
- medial border of scapula from level of spine to inferior angle
Where is the distal attachment for r. minor?
- medial end of scapular spine
what are the actions of r. minor and major?
- BOTH retract, elevate, and rotate scapula downward as well as fix it to thoracic wall
What innervates the r. major and minor muscle?
- Dorsal scapular nerve
What are the main muscles in shoulder shrug?
- trapezius
- levator scapulae
Where is the proximal attachment of the levator scapulae?
- posterior tubercules of transverse processes of C1-4
Where is the distal attachment of the levator scapulae?
- medial border of scapular, superior part of scapular spine
______ muscle elevates scapula and tilts glenoid fossa inferiorly by rotating scapula
- levator scapulae
What innervates the levator scapulae?
- dorsal scapular nerve and cervical spinal nerves (C3-C4)
Can the levator scapulae retract the scapula?
- NOPE
What actions do the rhomboid major and minor have on the scapula?
- elevate
- retract
- downward rotation
What actions does the levator scapulae have on the scapula?
- elevates
- downward rotation
What innervates the pec major, minor, subclavius, and serratus anterior?
- brachial plexus
What is the proximal attachment of the pectoralis major?
- clavicular and sternocostal attachments
- ant. surface of medial 1/2 of clavicle
- an. surface of sternum and superior 6 costal cartilages
What is the distal attachment of the pec. major?
- lateral lip of intertubercular sulcus
what are the actions of the pec major?
- adducts and medially rotates humerus
- draws scapula anteriorly and inferiorly (via clavicle)
- clavicular portion flexes humerus
- sternal portion can extend humerus while it is in this flexed position
What portion of the pec major extends humerus?
- sternal portion
What portion of pec major flexes humerus?
- clavicular portion
What muscle is innervated by the lateral and medial pectoral nerves?
- pectoralis major
Where does the pectoralis minor attach proximally?
- 3rd - 5th ribs near costal cartilages
Where is the distal attachment of the pec minor?
- coracoid process of scapula
What are the actions of the pec minor?
- stabilizes scapula by pulling it anteriorly and inferiorly against posterior thoracic wall
What innervates the pec minor?
- medial pectoral nerve (usually pierced by this nerve)
Where is the proximal attachment of the serratus anterior?
- external surfaces of lateral parts of ribes 1-9
Where is the distal attachment of serratus anterior?
- anterior surface of medial border of scapula
What are the actions of serratus anterior?
- protracts scapula
- rotates scapula
- holds scapula against thorax
What innervates the serratus anterior?
- long thoracic nerve
What are the actions of the serratus anterior on scapula?
- protraction and upward rotation of scapula
- allows full abduction of humerus; arms raised above head
- holds scapula against thorax
What causes a medial wining of scapula?
- damage to long thoracic nerve
- serratus anterior affected
- protrudes
Where is the proximal attachment of subclavius?
- junction of 1st rib and its costal cartilage
Where is the distal attachment of subclavius?
- inferior surface of middle 1/3 of clavicle
What does the subclavius do?
- anchors and depresses clavicle
- does not move it stabilizes clavicle
what is the innervation of subclavius?
- nerve to subclavius
- off of superior trunk
