Exam #6: Scapular & Pectoral Regions Flashcards
Review the bony landmarks of the clavicle.
Netter card
Review the bony landmarks of the scapula.
Netter card
Review the bony landmarks of the humerus.
Netter card
What is the difference between the anatomical and surgical necks of the humerus?
Anatomical= just distal to the humeral head; separates the head from the tubercles
Surgical= thinnest part of the humerus is commonly injured & most commonly requires surgery
List the 3 major joints of the shoulder from medial to lateral. What types of joints are these?
Medial= Sternoclavicular (saddle)
Intermediate= Acromioclavicular (plane)
Lateral= Glenohumeral (ball & socket)
Review the radiographic anatomy of the shoulder.
N/A
What is the function of the sternoclavicular joint?
Transmission of force from the thorax to the arm
What ligaments compose the sternoclavicular joint?
- Anterior & posterior sternoclavicular ligaments
- Interclavicular ligaments
What is the function of the acromioclavicular joint?
Holds the clavicle onto the scapula
What ligaments form the acromioclaicular joint?
1x Acromioclavicular ligament
2x Coracoclavicular ligaments
What is an AC separation?
Tearing of the acromioclavicular & coracoclavicular ligaments
Where does a clavicle fracture usually occur?
Weakest point= between medial 2/3 & lateral 1/3 of the clavicle
What are the typical mechanisms for an AC joint separation & clavicle fracture?
1) Fall onto an outstretched arm
2) Fall onto a shoulder
Clinically, how can you tell the difference between AC separation and clavicle fracture?
With a clavicle fracture the patient will naturally have a tendency to hold the injured arm “up” to take weight off of it
What ligaments form the glenohumeral joint?
Superior= coracoacromial ligament–>superior reinforcement
Anterior= glenohumeral ligaments–>joint capsule
- Superior
- Middle
- Inferior
Glenoid labrum
What is the most common presentation of a shoulder dislocation?
Inferior & anterior b/c of a lack of inferior ligaments + posterior muscles (rotator cuff)
What are the axio-appendicular muscles of the shoulder?
Muscles that attach from the body (thorax) to the shoulder; these are the “extrinsic” muscles of the shoulder
What are the scapulohumeral muscles of the shoulder?
Muscles of the shoulder itself; these are the intrinsic muscles of the shoulder
List the anterior axio-appendicular muscles of the shoulder.
Pectoralis major
Pectoralis minor
Subclavius
Serratus anterior
List the posterior axio-appendicular muscles of the shoulder.
Trapezius Lat. dorsi Levator scapulae Rhomboid major Rhomboid minor
List the scapulohumeral muscles of the shoulder.
Deltoid Teres major Supraspinatus Infraspinatus Teres minor Subscapularis
What is the function of the pectoralis major muscle?
Adduction and medial rotation arm
What nerves innervates the pectoralis major?
Medial & lateral branches of the pectoral nerve
What is the function of the pectoralis minor?
Stabilization of the scapula on the trunk
What nerve innervates the pectoralis minor?
Medial pectoral nerve
*Remember minor= only 1 branch b/c its small & “m” for medial
What is the function of the subclavius?
Depression of the clavicle
What nerve innervates the subclavius?
Nerve to the subclavius
What is the function of the serratus anterior?
- Protracts the scapula
- Rotates the scapula
- Holds the scapula onto the rib cage
What nerve innervates the serratus anterior?
Long thoracic nerve
What is clinically important to remember about the anatomical location of the long thoracic nerve? What happens when there is damage to this nerve?
- The long thoracic nerve (serratus anterior) is a very superficial structure contained within the subcutaneous tissue; thus it is commonly injured
- Damage= “winged scapula” & the individual is unable to abduct the arm past 90 degrees i.e. overhead
What is the function of the trapezius?
Elevates, retracts, rotates (with serratus anterior), and depresses the scapula
*Note that the trapezius has a very large origin; thus, it has the widest variety of functions
What is the only muscle not innervated by brachial plexus?
Trapezius
What nerve innervates the trapezius muscle?
Accessory nerve or CN XI
What is the function of the levator scapulae, rhomboid minor, and rhomboid major?
Elevation and retraction of the scapula
What muscles are innervated by the dorsal scapular nerve?
Levator scapulae
Rhomboid major
Rhomboid minor
What is the function of the Latissimus Dorsi?
Adduction, extension, and medial rotation of the humerus
What nerve innervates the Latissimus Dorsi?
Thoracodorsal nerve
What muscles are involved in the elevation of the shoulder?
Mainly the trapezius
- levator scapulae
- rhomboids
What forces and muscles are involved in the depression of the shoulder?
Mainly gravity
- Pectoralis muscles
- Lat. dorsi
- Trapezius
- Serratus anterior
What muscles are involved in the protraction of the scapula?
Mainly the serratus anterior
- Pectoralis muscles
What muscles are involved in the retraction of the scapula?
Mainly the trapezius
- Rhomboids
- Lat. dorsi
What muscles are involved in superior rotation of the scapula?
Trapezius
Serratus anterior
What muscles are involved in inferior rotation of the scapula?
Mainly the Lat. Dorsi
- gravity
- Levator scapulae
- Rhomboids
- Pectoralis muscles
What is the function of the deltoid?
Deltoid= flexes, abducts, & extends the arm at the shoulder
- Lateral= abduct - Anterior= flex - Posterior= extend
What nerve innervates the deltoid?
Axillary nerve
What is the function of the teres major?
Adducts & medially (internally) rotates the humerus *assists the latissimus dorsi
What nerve innervates the teres major?
Lower subscapular nerve
What two intrinsic muscles of the shoulder DO NOT form the rotator cuff?
Deltoid
Teres major
What four muscles make the rotator cuff?
Remember SITS
S= Supraspinatus I= Infraspinatus T= Teres minor S= Subcapularis
What is the function of the supraspinatus?
Abduction of the humerus (first 15 degrees) & then the deltoid kicks in
*Note that this is the only intrinsic muscle of the shoulder that DOES NOT rotate the humerus
What is the function of the infraspinatus?
lateral rotator of the humerus
What is the function of the teres minor?
lateral rotator of the humerus
What two muscles perform lateral rotation of the humerus?
Infraspinatus
Teres minor
*There are NO other muscles laterally rotate the humerus; if there is damage, humerus is medially rotated at rest because of a lack of tonic innervation
What is the function of the subscapularis?
Medial rotation of the humerus
What are the three major branches of the subclavian artery?
Common carotid
Vertebral
Thyrocervical trunk
What are the branches of the thyrocervical trunk?
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What is the axillary artery?
Continuation of the subclavian artery past the lateral border of the 1st rib
Where does the axillary artery end? What does it become?
Ends at the inferior border of the teres major
*Becomes the brachial artery
What are the borders of the first part of the axillary artery?
1st rib–> medial pectoralis minor
What are the borders of the second part of the axllary artery?
Posterior to the pectoralis minor
What are the borders of the third part of the axillary artery?
Lateral pectoralis minor–> teres major
What artery branches from the first part of the axillary artery?
Superior thoracic a. (1st & 2nd intercostal spaces)
What arteries branch from the second part of the axillary artery?
Thoraco-acromial artery
- Pectoral
- Deltoid
- Acromial
- Clavicular
Lateral thoracic artery (serratus anterior m.)
What arteries branch from the third part of the axillary artery?
- Subscapular artery
1) Circumflex scapular
2) Thoracodorsal (Lat. dorsi m.) - Anterior circumflex humeral artery
- Posterior circumflex humeral artery
What arteries anastomose in the region of the scapula?
- Dorsal scapular & thoracodorsal–in the region of the inferior angle of the scapula
- Suprascapular & circumflex scapular–in the region of the posterior arcomion
What arteries anastomose in the region of the humerus?
Anterior & posterior circumflex humeral
What is the triangular space? What are the borders?
This is a surgical landmark for the circumflex scapular artery
- Lateral= long head of the biceps
- Superior= teres minor
- Inferior= teres major
What are the borders of the quadrangular space?
- Lateral= surgical neck of the humerus
- Medial= long head of the triceps
- Superior= teres minor
- Inferior= teres major
What are the contents of the quadrangular space?
1) Axillary nerve
2) Circumflex humeral artery
What is the clinical importance of the quadrangular space?
Fracture of the surgical neck of the humerus damages the contents of this space
- Damage to the axillary nerve leads to atrophy of the deltoid muscle
What deep veins accompany the axillary artery?
Axillary vein
Inferior= brachial Superior= subclavian
Describe the superficial veins of the upper limb.
- Lateral cephalic vein & medial basilic vein join at the medial cubital vein
- BOTH continue into the upper arm as the veins of the same name
Describe the association between the axillary lymph nodes & cancer.
The more lateral the lymph nodes with metastasis, the better the prognosis for cancer