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Block 1 - Gross - Dissector Pectoral Region & Breast

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What is the mammary gland?
A modified sweat gland
Where is the mammary gland entirely contained within?
It is entirely contained within the subcutaneous tissue
What are the 3 important glandular internal gross features?
The secretory glands, lactiferous ducts, and lactiferous sinuses
What is the reason that the breast is a common site fo rthe development of cancer?
The fact that it is glandular
What is the externally important feature of the breast?
The nipple
What surrounds the nipple?
The areola
Each of the approximately 20 _________ sinuses have an individual opening on the nipple.
Lactiferous
Where is a breasts arterial supply derived from?
It is derived from branches of the internal thoracic artery, lateral thoracic artery, the thoracoacromial artery, and posterior intercostal arteries
Venous drainage follows what?
Arterial supply
Where does venous drainage primarily drain into?
The axillary vein
Secondarily, where does the venous drainage go?
Into the internal thoracic vein
Where does lymph pass from, and where does it end up?
It passes from the nipple, areola, and lodules to the subareolar lymphatic plexus
From the subareolar lymphatic plexus, where does most (75%) of it go?
It goes to the axillary lymph nodes
How does this lymph get to the axillary lymph nodes?
It travels via the pectoral lymph nodes
What is very important to consider when performing a breast exam on a patient?
It is important to consider the axillary nodes during a breast exam
Where does the other 25% go?
It goes to the parasternal lymph nodes
Does lymph travel anywhere else?
A small amount of lymph goes to the opposite breast and to the abdominal wall and downward
Where do lymphatic vessels of the skin of the breast drain into?
They drain into the axillary, inferior deep cervical, infraclavicular, and parasternal lymph nodes
Where does lymph from the axillary lymph nodes subsequently drain into?
It drains into the subclavian lymph trunk
Where does lymph from the parasternal nodes enter?
It enters the bronchomediastinal trunk
What is the origin of the pectoralis major?
The crest of the greater tubercle of the humerus
What is the action of the pectoralis major?
It flexes and adducts the arm, and medially rotates the arm
What innervates the pectoralis major?
The medial and lateral pectoral nerves (C5-T1)
What artery feeds the pectoralis major?
The pectoral branch of the thoracoacromial trunk
What does it mean if the deep faschia of the anterior surface is fused to the faschia of the mammary gland?
It is an important clinical indication of breast disease
What is the origin of the pectoralis minor?
Ribs 3-5
What is the insertion of the pectoralis minor?
The coracoid process of the scapula
What is the action of the pectoralis minor?
It draws the scapula forward, medialward, and downward
What innervates the pectoralis minor?
The medial pectoral nerve (C8, T1)
What artery feeds the pectoralis minor?
The pectoral branch of the thoracoacromial trunk
Branches of what nerve usually pierce the pectoralis minor in order to reach the pectoralis major?
The medial pectoral nerve
What is the origin of the serratus anterior?
Ribs 1-8 or 9
What is the insertion of the serratus anterior?
The medial border of the scapula on its costal (deep) surface
What is the action of the serratus anterior?
It draws the scapula forward, and the inferior fibers rotate the scapula superiorly
What innervates the serratus anterior?
The long thoracic nerve (from ventral rami C5-C7)
What is the artery that feeds the serratus anterior?
The lateral thoracic artery
What does a lesion of the long thoracic nerve cause, and where?
It causes winging in the medial border of the scapula
What is winging?
It is when the scapula falls away from the posterior chest wall and looks like an angel's wing
What does the human circulatory system contain two of?
It contains two complete circuits
From where do the lateral cutaneous branches (anterior and posterior) of intercostal nerves arise and to where do they distribute?
The lateral cutaneous branches of a typical intercostal nerve arise lateral to the angles of the ribs, divide into anterior and posterior branches, and supply the skin of the thoracic and abdominal walls.
Is any pinkish mammary glandular tissue visible?
It is likely that your cadaver does not have any appreciable mammary tissue. Most of the cadavers are elderly.
What are suspensory ligaments of the mammary glands?
The suspensory ligaments are fibrous condensations of the connective tissue stroma which are prominent in the superior part of the mammary gland. These help support the lobules of the gland and attach it to the dermis of the overlying skin.
Why are the lateral pectoral and medial pectoral nerves reversed?
Both of these nerves supply the pectoralis major. The "medial" and "lateral" designations of these two nerves refers to the cords of the brachial plexus from which they are derived. (Do not worry about this now, but it will haunt you later!) They are not topographic designations. (To remember which is which, think about the Medial pectoral nerve being a Major nerve which supplies both the pectoralis Major and the pectoralis Minor. The Lateral nerve is a Little nerve, and only innervates pectoralis major.)
They are medial
What is the origin of the deltoid?
The lateral 1/3 of the clavicle, acromion, the lower lip of the crest of the spine of the scapula
What is the insertion of the deltoid?
The deltoid tuberosity of the humerus
What is the action of the deltoid?
The deltoid abducts the arm
What do the anterior fibers of the deltoid do?
They flex and medially rotate the arm
What do the posterior fibers of the deltoid do?
They extend and laterally rotate the arm
What innervates the deltoid?
The axillary nerve (C5,6) from the posterior cord of the brachial plexus
What artery feeds the deltoid?
The posterior circumflex humeral artery
What is the deltoid the principle abductor of?
The arm
Unfortunately for the deltoid, it cannot initiate the action of abducting the arm. What assists it?
The supraspinous muscle
What is the origin of the supraspinatis muscle
The supraspinatous fossa
What is the insertion of the supraspinatus?
The greater tubercle of the humerus (highest facet)
What is the action of the supraspinatus?
It abducts the arm (initiates abduction)
What innervates the supraspinatus?
The suprascapular nerve (C5,6) from the superior trunk of the brachial plexus
What artery supplies the supraspinatus?
The suprascapular artery
What is the supraspinatus a member of?
The rotator cuff group
What is the origin of the teres major?
The dorsal surface of the inferior angle of the scapula
What is the insertion of the teres major?
The crest of the lesser tubercle of the humerus
What is the action of the teres major?
It adducts the arm, medially rotates the arm, and assists in arm extension
What innervates the teres major?
The lower subscapular nerve (C5,6) from the posterior cord of the brachial plexus
What artery feeds the teres major?
The circumflex scapular artery
Where does the teres major insert relative to the latissimus dorsi?
It inserts beside the tendon of the latissimus dorsi
How does the teres major relate to the latissimus dorsi from a physical perspective?
It assists the latissimus dorsi in its actions
What is the origin of the teres minor?
The upper 2/3 of the lateral border of the scapula
What is the insertion of the teres minor?
The greater tubercle of the humerus (lowest facet)
What is the action of the teres minor?
It laterally rotates the arm
What innervates the teres minor?
The axillary nerve (C5,6) from the posterior cord of the brachial plexus
What artery feeds the teres minor?
The circumflex scapular artery
What does the teres minor do relating to the humerus and the glenoid fossa?
The teres minor fixes the head of the humerus in the glenoid fossa during the abduction & flexion of the arm
What group is the teres minor a member of?
The rotator cuff group
What is the superior lateral brachial cutaneous nerve?
It is a nerve that has branches entering the skin at the posterior border of the
What is the source of the axillary nerve?
The posterior cord of the brachial plexus
What is the branch of the axillary nerve
The superior lateral brachial cutaneous nerve
What is the motor function of the axillary nerve?
The deltoid and teres minor
What is the sensory function of the axillary nerve?
The skin of the upper lateral arm
What is the source
What branches off the posterior circumflex humeral artery?
The axillary artery
What does the posterior circumflex humeral vessels supply?
They supply the deltoid, arm muscles near the surgical neck of the humerus
What does the posterior circumflex humeral artery pass through?
It passes through the quadrangular space with the axillary nerve
What is the origin of the long head triceps brachii?
On the long head the infraglenoid tubercle of the scapula
What is the origin of the lateral head of the triceps brachii?
The posterolateral humerus & lateral intermuscular septum
What is the origin of the medial head of the triceps brachii?
Posteromedial surface of the inferior 1/2 of the humerus
What is the insertion of the triceps brachii?
The olecranon process of the ulna
What is the action of the triceps brachii?
It extends the forearm. The long head extends and adducts the arm
What innervates the triceps brachii?
The radial nerve
What artery supplies to the triceps brachii?
The deep brachial artery
What does the long head of the triceps separate into?
The triangular and quadrangular spaces
All three heads of the triceps brachii insert by what?
A common tendon
The long head of the triceps brachii muscle is closely related to the posterior border of what muscle?
The deltoid muscle
A branch of what artery can be found in the triangular space?
Branches of the circumflex scapular artery
What is the origin of the infraspinatus?
The infraspinatous fossa
What is the insertion of the infraspinatus?
The greater tubercle of the humerus
What is the action of the infraspinatus?
It laterally rotates the arm
What innervates the infraspinatus?
The suprascapular nerve
What artery feeds the infraspinatus?
The suprascapular artery
The infraspinatus, supraspinatus, teres minor and subscapularis are what muscles?
The rotator cuff muscles
What accessory nerve and vessels are attached to the deep surface of the trapezius, and must be cut before dissecting the supraspinatus?
The subtrapezial plexus and transverse cervical arteries
What does the transverse scapular ligament span?
It spans the suprascapular notch of the scapula
What does the transverse scapular ligament convert the suprascular notch into?
Into a foramen
What artery passes superior to the transverse scapular ligament?
The suprascapular artery
What artery passes inferior to the transverse scapular ligament?
The suprascapular ligament inferior
What is the mnemonic to remember which goes over and which goes under?
The Army (A for artery) goes over the bridge, and the Navy (nerve) goes under the bridge
What is the source of the suprascapular nerve?
The superior trunk of the brachial plexus (C5-C6)
What branches off the suprascapular nerve?
None named
What does the suprascapular nerve motorize?
The supraspinatus muscle and the infraspinatus muscle
Sensory information if provided via the suprascapular nerve from what?
Nothing
What does the suprascapular nerve pass through?
It passes through the suprascapular notch inferior to the superior transverse scapular ligament
What is the origin of the platysma muscle?
The faschia overlying the pectoralis muscle and deltoid muscles
What is the insertion of the platysma?
The inferior border of the mandible and lower face
What is the action of the platysma?
It draws the corners of the mouth down. It aids in depression of the mandible
What innervates the platysma?
The cervical branch of the facial nerve (VII)
What artery supplies the platysma?
The facial artery
What are the tributaries of the cephalic vein?
The dorsal veins of the hand laterally, and superficial veins of the forearm
What does the cephalic vein drain into?
The axillary
What region is drained via the cephalic vein?
The lateral hand & forearm
What structure usually shunts some blood to the basilic vein?
The median cubital
Where do the cephalic and basilic veins begin from the lateral and medial sides of?
They begin from the lateral and medial sides of the dorsal venous arch
Is the cephalic vein anterior or posterior to the elbow?
Anterior
The cephalic vein penetrates the __________ membrane deep to the superior fibers of the pectoralis major muscle and terminates deeply into the _________ vein of the axilla
costocoracoid, axillary
While the basilic vein ascends the medial side of the forearm, the cephalic vein passes the ____ side of the forearm?
Lateral
Before reaching the axilla, the basilic vein travels through what compartment?
The neurovascular compartment of the arm
Once at the axilla, the basilic vein joints the brachial veins to form what vein?
The axillary vein
What vein connects the cephalic and basilic veins in the superficial faschia covering the cubital fossa at the elbow?
The median cubital vein
What are the 8 major cutaneous nerves that can be identified in the upper limb?
Posterior brachial, medial brachial, intercostobrachial, lateral brachial, medial antebrachial, lateral antebrachial, posterior antebrachial, and superficial brachial
Immediately deep to the clavicular fibers are branches of what 3 things?
The thoracoacromial arterial trunk, the lateral pectoral nerve, and the terminal course of the cephalic vein
The thoracoacromial trunk is a branch of the second part of what artery?
The axillary artery
What is the source of the pectoral artery?
The thoracoacromial trunk
What does the pectoral artery supply to?
Pectoralis major and pectoralis minor
The pectoral artery accompanies what nerve?
The lateral pectoral nerve
What four branches of the arterial trunk are in the clavipectoral faschia?
Pectoral branches, deltoid branch, acromial branch, and clavicular branch
The acromial branch is small and passes deep to the border of what muscle?
The deltoid muscle
What branch passes between the deltoid and the pectoralis major muscles and accompanies the cephalic vein?
The deltoid branch
What branch supplies the subclavius muscle and the sternoclavicular joint?
The clavicular branch
What nerve courses with the pectoral vessels through the costocoracoid membrane?
The lateral pectoral nerve
What does the lateral pectoral nerve innervate?
It innervates the pectoralis major muscle
What is the source of the lateral pectoral nerve?
The lateral cord of the brachial plexus
What is motorized by the lateral pectoral nerve?
The pectoralis major
The lateral pectoral nerve pierces through a faschia. What is this faschia called?
The clavipectoral
The lateral pectoral nerve communicates with the medial pectoral nerve, which is (anterior / posterior) to the axillary artery
Anterior
What is the deep faschia of the pectoralis minor?
The clavipectoral faschia
The clavipectoral faschia covers what two muscles extending superioly from the clavicle to the axillary faschia superiorly?
The subclavius and pectoralis minor muscles
The axillary faschia forms the base what?
The axilla
The axillary faschia is continuous with the faschia of what muscle posteriorly?
The latissimus dorsi
What is the part of the clavipectoral faschia called that lies between the clavicle and the pectoralis minor muscle?
The costocaracoid membrane
What vein pierces the costocoracoid membrane?
The cephalic vein
What else pierces the costocoracoid membrane?
The lateral pectoral nerve and the thoracoacromial trunk
What is the suspensory ligament of the axilla called?
The calvipectoral faschia
What does the calvipectoral faschia help support?
The axillary faschia
What pierces the medial pectoral nerve?
The pectoralis minor
Why is the pectoralis minor muscle an important landmark in the axilla?
Its position divides the axillary artery into 3 parts

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