Lecture 16 - Muscles Of The Pectoral & Scapular Regions Flashcards
What are the 4 muscles of the anterior axio-appendicular region?
- pectoralis major/minor
- subclavius
- Serratus anterior
What are the 2 origins of the pectoralis major?
- Clavicular Head: Anterior surface of medial half of clavicle
- Sternocostal Head: Anterior surface of sternum, Costal cartilages 1-6 (or 1-7)
What is the insertion of the pectoralis major?
- Lateral lip of the bicipital groove on humerus (both heads)
- Attachments twist on one another so that the sternal head comes to be superior to the clavicular head on the bicipital groove
What is the innervation of the pectoralis major?
- Medial Pectoral Nerve
- Lateral Pectoral Nerve
What are the main actions of the pectoralis major?
- Shoulder adduction & medial rotation
- Clavicular head only: shoulder Flexion from an extended position
- Sternal head only: shoulder extension from a flexed position
What is the origin/insertion/innervation/main action of the pectoralis minor?
- O: Anterior and superior surfaces of ribs 3, 4, 5, just lateral to costal cartilages
- I: Coracoid process of scapula
- Inn: Medial Pectoral Nerve
- MA: Protraction of scapula
What is the origin/insertion/innervation/main action of the subclavius?
- O: Rib 1 at junction of rib & costal cartilage
- I: Groove on inferior surface of middle 1/3 clavicle
- Inn: Nerve to Subclavius
- MA: Anchors & depresses clavicle when upper limb is moving
What is the origin/insertion/innervation/main action of the Serratus anterior?
- O: External lateral surfaces of first 8 (or 9) ribs
- I: Anterior surface of medial border scapula
- Inn: Long Thoracic Nerve
- MA: Scapular protraction & upward rotation
What are the 5 muscles of the posterior axio-appendicular & scapulohumeral regions
- trapezius
- latissimus dorsi
- levator scapulae
- rhomboids major/minor
What are the origins of the trapezius?
- External occipital crest
- Ligamentum nuchae
- Spinous processes of C7-T12 (aponeurotic) & supraspinous ligament
What are the insertions of the trapezius?
- Upper fibers descend to the lateral 1/3 of posterior clavicle
- Middle fibers run horizontally along scapular spine to the acromion process of scapula
- Lower fibers ascend to the scapular spine
What is the innervation of the trapezius?
- CN XI (accessory nerve)
What are the main actions of the trapezius?
- Upper scapular elevation & upward rotation, neck extension & side flexion
- Middle scapular retraction
- Lower scapular depression & upward rotation
What is the origins of the latissimus dorsi?
- Spinous processes of inferior 6 thoracic vertebrae & interspinous ligaments
- Thoracolumbar fascia
- Posterior iliac crest lower 3 or 4 ribs
What is the insertion/innervation of the latissimus dorsi?
- I: Floor of bicipital groove
- Inn: Thoracodorsal nerve
What are the main actions of the latissimus dorsi?
- Shoulder extension back to neutral from a flexed position
- Shoulder medial rotation
- Shoulder adduction
What is the origin/insertion/innervation/main action of the levator scapulae?
- O: C1 to C4 transverse processes
- I: Superior portion of medial border of scapula
- Inn: Dorsal Scapular nerve
- MA: Scapular elevation & downward rotation
What is the origin/insertion/innervation/main action of the rhomboids major?
- O: T2 to T5 spinous processes
- I: Medial border of scapula
- Inn: Dorsal Scapular nerve
- MA: Scapular retraction, downward rotation & elevation
What is the origin/insertion/innervation/main action of the rhomboids minor?
- O: Lower portion of ligamentum nuchae, C7 & T1 spinous processes
- I: Medial end of scapular spine at medial border of scapula
- Inn: Dorsal Scapular nerve
- MA: Scapular retraction, downward rotation & elevation
What are the 6 muscles of the scapulohumeral region?
- Supraspinatus
- Infraspinatus
- teres minor/major
- subscapularis
- deltoid
What is the rotator cuff?
- made up of 4 muscles
- use the acronym “SITS”; Supraspinatus, infraspinatus, teres minor, subscapularis
- made up of 1 anterior cuff muscle; subscapularis
- made up of 3 posterior cuff muscles; Supraspinatus, infraspinatus, teres minor
What is the origin/insertion/innervation/main action of the Supraspinatus?
- O: Supraspinous fossa of the scapula
- I: Superior portion of greater tubercle of humerus
- Inn: Suprascapular nerve
- MA: Initiates abduction of the shoulder (first 150 degrees), Assists with lateral rotation of the shoulder
What is the origin/insertion/innervation/main action of the infraspinatus?
- O: Infraspinous fossa of the scapula
- I: Middle portion of greater tubercle of humerus
- Inn: Suprascapular nerve
- MA: Lateral rotation of the shoulder
What is the origin/insertion/innervation/main action of the teres minor?
- O: Mid-portion of lateral border of scapular
- I: Inferior portion of greater tubercle of humerus
- Inn: Axillary Nerve
- MA: Lateral rotation of the shoulder
What is the origin/insertion/innervation/main action of the subscapularis?
- O: Subscapular fossa of the scapula
- I: Lesser tubercle of the humerus
- Inn: Upper & Lower Subscapular nerve
- MA: Shoulder medial rotation
What is the origin/insertion/innervation/main action of the teres major?
- O: Poserior surface of inferior angle of scapula
- I: Medial lip of bicipital groove of humerus
- Inn: Lower Subscapular nerve
- MA: Shoulder medial rotation, Shoulder adduction & Shoulder extension from a flexed position
What is the origins of the deltoid?
- Anterior portion of lateral 1/3 clavicle
- Lateral portion of acromion process – Inferior edge of scapular spine
- Forms 3 distinct portions:
- Anterior - front of the joint
- Middle - top of the joint
- Posterior - behind the joint
What is the insertion/innervation/main action of the deltoid?
- I: Deltoid tuberosity of humerus
- Inn: Axillary Nerve
- MA: Abduction of Shoulder (beyond 15°), Anterior head - assists with shoulder flexion & medial rotation, Posterior head - assists with shoulder extension & lateral rotation
