Pectoral Region and Breast Practice Quiz

In the axilla the pectoralis minor is a landmark, being closely related to several structures including:

- Cords of the brachial plexus - Lateral thoracic artery - Medial pectoral nerve - Second part of the axillary artery ------------------- The cephalic vein is the only structure listed that does not have a special relationship to pectoralis minor. The cords of the brachial plexus are found deep to pectoralis minor. The second part of the axillary artery is defined as the segment of the axillary artery which is covered by the pectoralis minor muscle. So, branches of the second part of the axillary artery, including the lateral thoracic artery, lie deep to pectoralis minor. The medial pectoral nerve pierces pectoralis minor to reach pectoralis major.

After being thrown from a motorcycle moving at high speed, a 16-year-old female was found to have a paralyzed right pectoralis major muscle. Which set of movements at the shoulder joint would be found greatly weakened?

Adduction and flexion ----------------- Pectoralis major flexes, adducts, and medially rotates the arm. It is innervated by the lateral and medial pectoral nerves, from the lateral and medial cords of the brachial plexus.

The prognosis in breast cancer is poorer as more proximal lymph nodes are found to have cancerous cells in them. Spread of cancer to which of the following axillary nodes would indicate the worst prognosis?

Apical lymph nodes ------------------ As lymph drains from the breast into the axillary system, it moves from the pectoral or anterior axillary nodes, to the central axillary nodes, and then to the apical axillary nodes, and then usually forms a subclavian lymph trunk that drains back into the venous system (although sometimes into supraclavicular nodes). Breast cancers would not usually spread to anterior axillary or humeral nodes, which receive lymph from the distal upper limb, or posterior axillary or subscapular nodes, which receive lymph from the posterior shoulder. If cancer is found in the apical axillary nodes, this is a sign that the cancer has spread through the regional lymphatic system and may have metastasized to the rest of the body.

During the planning of therapeutic intervention for a 54-year-old female patient with cancer of the right breast, a 3rd year medical student would need to first consider where most of the cancer cells would metastasize, which would be:

Axillary lymph nodes ------------- About 75% of the lymph from the breast goes to the axillary lymph nodes via the pectoral lymph nodes. This is the most important place to check for metastasis of the cancer cells! The lymph from the axillary nodes eventually drains into the subclavian lymph trunk. Most of the rest of the lymph drains into the parasternal lymph nodes, while a small amount drains to the abdominal wall and the opposite breast. The anterior mediastinum is not an important place for lymphatic drainage from the breast.

A man is in an auto accident and sustains several injuries, among them are: 1. Skin lacerations: on the back of his head in the occipital area, on his chest just above the nipple, on the lateral side of his arm, lateral forearm at midlength, dorsal hand between his thumb and index finger 2. Abrasions and contusions (bruises) about his right shoulder 3. A fractured right radius near its distal end After X-ray examination, you are called upon to suture his lacerations in the emergency room. Which laceration (from your observations in the gross anatomy lab) would you expect to be the most difficult to suture because of thick skin?

Back of his head in the occipital area ------------------ Remember back to the very early labs-- the back of the head is the one place in the body where the skin is the thickest. The skin should be thinner in all of the other locations.

A sixteen-year-old boy received a superficial cut on the ulnar side of his forearm. The superficial vein most likely affected is the:

Basilic vein ------------- The basilic vein is on the ulnar side of the forearm--near the 5th finger. The basilic vein takes rise from the medial side of the dorsal venous arch of the hand, and drains blood from the medial (ulnar) side of the arm. The cephalic vein takes origin from the lateral side of the dorsal venous arch of the hand, and then runs up the lateral (radial) forearm. The median antebrachial vein runs down the center of the anterior forearm, draining into the median cubital vein. The median cubital vein connects the cephalic vein to the basilic vein in the cubital fossa. Finally, the radial vein is a deep vein that runs with the radial artery.

In the process of escaping from T. rex in Jurassic Park the heroine punctures the skin on the medial side of her wrist on a spiny bush. A few days later, due to the toxin, an infection is seen spreading up the medial side of her arm along the large cutaneous vein extending from the dorsum of her hand to the medial side of her arm. The vein involved is the:

Basilic vein ---------------- There are two large cutaneous veins running up the forearm. Both veins take origin from the dorsal venous arch of the hand and run up the lateral and medial sides of the forearm. On the medial side (near the 5th digit) there is the basilic vein. On the lateral side, there is the cephalic vein. Since the infection is on the medial side, the correct answer is the basilic vein. (Remember that the hands are supinated in the anatomical position--this comes in handy when you are thinking about the medial and lateral sides of the forearm.) The brachial vein runs with the brachial artery-- it is a deep vein that ends at the level of the elbow. The ulnar vein runs with the ulnar artery, draining the ulnar side of the forearm. Neither of these veins are located in superficial tissue. The median cubital vein is a cutaneous vein, but it is short and only found in the median cubital fossa. It provides a connection between the cephalic vein and basilic vein.

A woman with breast cancer subsequently develops metastases in her vertebral column. The most direct route for spread of the tumor to the vertebral column was via:

Branches of the intercostal veins ------------------- The most likely route for the cancer to reach the vertebral column is through the intercostal veins, i.e. hematogenous spread. The cephalic vein and thoracoacromial vein would not be draining the breast, and the lateral thoracic vein would not be directing blood toward the vertebral column. Lymphatic vessels may carry some tumor cells to the axillary lymph nodes and may participate in the spread of the cancer, but this isn't the best answer for this question. The most direct way for the cancer to spread to the vertebral column is through the venous system.

In lymphatic drainage of the breast, the major portion (about 75%) enters eventually into which group of nodes?

Central axillary lymph nodes ---------------- About 75% of the lymph draining the breast goes to the axillary lymph nodes, via the pectoral lymph nodes. All of this lymph from the pectoral lymph nodes must drain to the central lymph nodes as well. This is why it is so important to examine all these groups of axillary lymph nodes when performing a breast exam. Most of the rest of the lymph drainage from the breast goes to the parasternal nodes, although a small amount goes to the opposite breast and a small amount drains to the abdominal wall.

A sixteen-year-old boy receives a superficial cut on the thumb side of his forearm. The superficial vein most likely affected is the:

Cephalic vein ------------ There are two large cutaneous veins running up the arm. Both veins take origin from the dorsal venous arch of the hand and run up the lateral and medial sides of the arm. On the medial side (near the 5th digit) there is the basilic vein. On the lateral side (by the thumb), there is the cephalic vein. Since the infection is on the thumb side of the forearm, the correct answer is the cephalic vein. The median antebrachial vein runs down the center of the anterior forearm. The median cubital vein connects the cephalic vein to the basilic vein in the cubital fossa. Finally, the radial vein is a deep vein that runs with the radial artery.

A man is in an auto accident and sustains several injuries, among them are: 1. Skin lacerations: on the back of his head in the occipital area, on his chest just above the nipple, on the lateral side of his arm, lateral forearm at midlength, dorsal hand between his thumb and index finger 2. Abrasions and contusions (bruises) about his right shoulder 3. A fractured right radius near its distal end The injured nerve (from the skin of his hand) contains afferent nerve fibers that travel through which part of a spinal nerve?

Dorsal root -------------- The dorsal root of a spinal nerve contains afferent sensory fibers, while the ventral root of a spinal nerve contains efferent motor fibers. The dorsal primary ramus, which is the first dorsal nerve branching from the spinal nerve, contributes motor innervation to the muscles of the back and gives off posterior cutaneous nerves which innervate the skin of the back. Although these cutaneous sensory nerves contain afferent fibers, there are no posterior cutaneous nerves on the skin of the hand, so this is not the correct answer. Finally, a gray ramus communicans is a structure that postganglionic sympathetic fibers use to leave the sympathetic chain ganglion to reach a ventral primary ramus.

Mastitis is a condition which involves:

Inflammation of the breast ---------------- Mastitis is an inflammation of the breast. It usually occurs during lactation and breast feeding and is usually caused by the organism Staphylococcus aureus. Treating a patient with mastitis that involves infection would include antibiotics, draining an abcess, and excising the diseased mammary duct.

Breast cancer cells can spread directly to the cranial cavity and brain via the vertebral venous plexus. Through which route can they reach this plexus?

Intercostal veins ---------------- Hematogenous spread through the intercostal veins is the easiest way for breast cancer to reach the internal vertebral venous plexus. It is true that the axillary lymph nodes drain 75% of the lymph from the breast, and the parasternal lymph nodes drain most of the remaining lymph. However, these lymphatic channels are not the major way that cancer would be transmitted to the internal vertebral venous plexus. This plexus of veins would be most likely to receive cancer cells transmitted through the blood. The internal thoracic vein drains some blood from the breast, but it would not direct the blood toward the vertebral column. The thoracromial artery and other arteries do not drain the breast; hence, they would not provide a route for spreading cancer.

While observing a mastectomy on a 60-year-old female patient, a medical student was asked by the surgeon to help tie off the arteries that supply the medial side of the breast. The artery that gives origin to these small branches is the:

Internal thoracic artery --------------- Small branches from the internal thoracic artery, known as medial mammary branches, supply the medial side of the mammary gland. The lateral side of the mammary gland is supplied by the lateral thoracic artery. The musculophrenic artery is a branch of the internal thoracic artery--it travels laterally and supplies blood to the 7th through 9th intercostal spaces. The posterior intercostal arteries are branches from the descending aorta--they supply the lateral and posterior portions of the intercostal space. The superior epigastric artery is a branch of the internal thoracic artery--it supplies the upper rectus abdominis muscle and the upper abdominal wall. The thoracoacromial artery supplies blood to the pectoral muscles, deltoid, subclavius, and the shoulder joint.

During insertion of an IV cannula in the median cubital vein, the patient suddenly lost feeling on the radial side of the forearm. What nerve was injured?

Lateral antebrachial cutaneous nerve ---------------- There are 3 nerves that might be damaged due to a venipuncture in the median cubital fossa. If the needle goes a bit lateral, the lateral antebrachial cutaneous nerve might be injured. This nerve is a branch of the musculocutaneous nerve which supplies the skin of the lateral side of the forearm. The patient's symptoms (loss of feeling on the radial side of the forearm) match with an injury to the lateral antebrachial cutaneous nerve. If the needle goes a bit medial, it could injure the medial antebrachial cutaneous nerve. This nerve is a direct branch of the medial cord of the brachial plexus--it innervates skin on the medial side of the forearm. If the needle goes too deep, the median nerve might be injured. This would cause the patient to lose sensation on the palmar side of the lateral 3.5 digits. The posterior antebrachial cutaneous nerve is a branch of the radial nerve which supplies the posterior forearm. The superficial radial nerve is a terminal branch of the radial nerve which supplies the dorsum of the hand and the dorsal side of the lateral 2.5 digits. Neither of these nerves would be affected by a venipuncture in the median cubital fossa!

While having an IV needle inserted into the cephalic vein of the forearm, the patient suddenly screamed in pain and felt tingling in part of the skin of the forearm supplied by the nerve accompanying the vein. What nerve was injured?

Lateral antebrachial cutaneous nerve ------------------ The lateral and medial antebrachial cutaneous nerves supply the skin of the lateral and medial side of the anterior forearm, respectively. The lateral antebrachial cutaneous nerve is a branch of the musculocutaneous nerve, which runs on the lateral forearm near the cephalic vein. So, this is the nerve that must have been injured. The medial antebrachial cutaneous nerve is a direct branch of the medial cord of the brachial plexus--it runs near the basilic vein. This nerve could be injured during a venipuncture to the basilic vein. The posterior antebrachial cutaneous is a branch of the radial nerve that supplies the skin on the posterior forearm--it is not located near any sites for venipuncture. Finally, the superficial radial nerve supplies cutaneous innervation to the dorsal side of the hand, including the dorsal side of the radial 2 1/2 digits.

During a motorcycle accident, an 18-year-old male landed on the right lateral side of his rib cage with his right upper limb abducted. In the hospital he was found to have "winging" of the right scapula. Which nerve was likely damaged in the accident?

Long thoracic nerve -------------- An injury to the long thoracic nerve denervates serratus anterior, meaning that there will be no muscle protracting the scapula and counteracting trapezius and the rhomboids, powerful retractors of the scapula. This means that the scapula will be winged backwards, which is this patient's main symptom. The long thoracic nerve is derived from the nerve roots of C5-7. This nerve is particularly vulnerable to iatrogenic injury during surgical procedures, such as mastectomies, because it is located on the superficial side of serratus anterior. The accessory nerve innervates trapezius--an injury to this nerve might lead to an inability to raise the acromion of the shoulder. The lateral pectoral nerve is a small nerve that provides innervation to pectoralis major. The phrenic nerve innervates the diaphragm. The vagus nerve provides parasympathetic innervation to the thorax and much of the abdominal viscera. The patient's symptoms do not fit with an injury to any of these nerves.

Because of scarring of a patient's median cubital vein, the technician chooses to insert an infusion needle into her basilic vein at the level of the medial epicondyle. Despite the certainty that the needle does not pass through the deep (investing) fascia, there is still a chance that it might nick or impale which nerve?

Medial antebrachial cutaneous nerve -------------- The basilic vein is on the medial side of the arm, so a venipuncture into the basilic vein might damage the medial antebrachial cutaneous nerve which also runs on the medial side of the arm. The brachial artery, median nerve, and radial nerve are deeper structures that would not be damaged during a venipuncture. The lateral antebrachial cutaneous nerve is near the cephalic vein, not the basilic vein.

In withdrawing a blood sample from the median cubital vein the needle passes slightly deep and medial; which nerve might possibly be injured?

Medial antebrachial cutaneous nerve ------------------ The medial antebrachial cutaneous nerve is a direct branch from the medial cord of the brachial plexus. Since it provides cutaneous sensation to the medial side of the anterior forearm, it is slightly medial to the medial cubital vein and could be injured by a needle. If the needle had gone laterally, it might have injured the lateral antebrachial cutaneous nerve, which is running down the lateral side of the anterior forearm. This nerve is a branch of the musculocutaneous nerve. The posterior antebrachial cutaneous nerve runs on the posterior surface of the arm--it comes from the radial nerve. The dorsal ulnar cutaneous nerve is the nerve which runs on the dorsal side of the hand, providing cutaneous innervation to the ulnar side of the wrist, hand, and the medial 1.5 fingers. Finally, the superficial radial nerve innervates the dorsum of the radial side of the hand.

In the process of doing an axillary lymph node dissection in a 50 year-old patient, the surgery resident cleans the space between the pectoralis major and minor muscles, in an attempt to remove all of the lateral pectoral lymph nodes. Upon recovery it is noted that the patient's lower pectoralis major is paralyzed. The nerve most likely injured is the:

Medial pectoral nerve ------------------- Since the medial pectoral nerve pierces pectoralis minor to reach pectoralis major, it seems likely for this nerve to be injured from trauma to the space between pectoralis minor and major. Also, remember that the medial pectoral nerve innervates the inferior part of pectoralis major, while the lateral pectoral nerve innervates the superior part of pectoralis major. The medial pectoral nerve innervates both pectoralis major and pectoralis minor, while the lateral pectoral nerve innervates pectoralis major only. These two nerves are named after their origin from two different cords of the brachial plexus. (This explains why their names and relative locations are reversed from what you might expect.) The thoracodorsal nerve (which is also derived from the brachial plexus) innervates latissimus dorsi, and is not involved with the pectoral muscles. The other two nerves, axillary and suprascapular, are also derived from the brachial plexus and will be studied along with the upper limb.

The vein of choice for withdrawing blood is the:

Median cubital vein --------------- The median cubital vein connects the cephalic and basilic veins in the cubital fossa. This vein shunts blood from the cephalic vein to the basilic vein. Venipunctures are usually done in the median cubital vein, so this is the best answer to pick. Another reason that median cubital vein is a favorite is the fact that it is anchored in place by a perforating vein connecting to the brachial veins - so that it doesn't move out of the way of the venipuncture needle. However, don't forget that venipunctures can be done in other veins, including the basilic and cephalic veins. Both of these veins arise from the dorsal venous arch of the hand--the basilic vein travels up the medial side of the arm and the cephalic vein travels up the lateral side of the arm. The median antebrachial vein travels in the center of the forearm and drains into the median cubital vein.

The lateral antebrachial cutaneous nerve comes from the:

Musculocutaneous nerve -------------------- The musculocutaneous nerve provides cutaneous innervation to the skin of the anterolateral side of the forearm through the lateral antebrachial cutaneous nerve. The axillary nerve supplies the skin of the upper lateral arm with the superior lateral brachial cutaneous nerve. The radial nerve supplies cutaneous innervation to the skin of the posterior arm, forearm, and hand through many different cutaneous nerves. The ulnar nerve supplies sensory innervation to the skin of the medial side of the wrist and hand and skin of the medial 1 1/2 digits on the palmar side, and 2 1/2 digits on the dorsum of the hand. If you are having problems conceptualizing these areas of cutaneous innervation, check out on-line color pictures in the dissector answers, or plate 481 in Netter's!

Upon finding a malignant tumor in the medial portion of the breast of a 40-year-old female, the surgeon began to search for the lymph nodes that would be the first ones reached by metastatic spread of cancer cells from this site. Which group(s) would have to be examined to determine whether metastasis had occurred?

Parasternal and pectoral lymph nodes ---------------- As lymph drains from the breast, the majority of fluid travels to two groups of lymph nodes: the axillary and the parasternal. 75% of the lymph goes to the axillary lymph nodes, with the pectoral nodes being the first axillary nodes to receive the drainage. So, the pectoral nodes would need to be inspected to determine whether cancer had spread to the axillary system. Central and apical nodes are also part of the axillary system. These nodes might receive cancerous cells, but they are more distal sites of drainage. Cancer would be most likely to metastasize to the pectoral nodes first. The parasternal nodes receive most of the lymph that does not drain into the axillary nodes. They are an especially important route of drainage from the medial side of the breast. So, it is also important to survey these nodes to determine whether cancer has spread into the lymphatics.

After a jarring blow to the left anterior shoulder region, a young field hockey player was told by an examining physician that she had a muscle tear that resulted directly from the superolateral distraction of a fractured coracoid process. Which muscle was torn?

Pectoralis minor -------------- Of the muscles listed, pectoralis minor is the only one which is attached to the coracoid process. The deltoid originates from the clavicle, acromion and scapular spine and inserts on the deltoid process of the humerus. Pectoralis major originates from the clavicle, sternum, and ribs and inserts on the crest of the greater tubercle of the humerus. Serratus anterior originates on the ribs and inserts on the medial border of the costal surface of the scapula. Subclavius originates on the first rib and inserts on the clavicle. So, none of these other muscles would be detached by a fracture of the coracoid process. What other muscles are attached to the coracoid process? Coracobrachialis and the short head of the biceps.

You are in the emergency room when a patient is brought in, the loser in a street fight. He has received a stab wound about 1.5 cm long in the right side of the chest about 1.5 cm below and 1 cm medial to the coracoid process of the scapula. He has lost a lot of bright red blood from a large (~1.2 cm in diameter) severed artery found deep at this location. Intravenous fluids are immediately administered and a surgeon is called in to repair the artery. He begins by making an incision through the skin and subcutaneous tissue just below the clavicle, then cuts the clavicular head of the pectoralis major muscle and retracts it downward to obtain sufficient exposure of the area. He next encounters a partially severed muscle running downward and medially from the coracoid process. He divides the remaining fibers of the muscle and has you retract it downward. This exposes a bloody fat-filled space full of vessels and nerves. The muscle running downward and medially from the coracoid process which was partially severed was the:

Pectoralis minor muscle --------------- Pectoralis minor inserts on the coracoid process of the scapula. Its origin is ribs 3-5, so it runs downward and medially from the coracoid process. Coracobrachialis is a muscle of the upper limb which takes origin from the coracoid process. However, it attaches to the shaft of the humerus and runs laterally. The long head of the biceps, subclavius, and subscapularis are not attached to the coracoid process.

You are in the emergency room when a patient is brought in, the loser in a street fight. He has received a stab wound about 1.5 cm long in the right side of the chest about 1.5 cm below and 1 cm medial to the coracoid process of the scapula. He has lost a lot of bright red blood from a large (~1.2 cm in diameter) severed artery found deep at this location. Intravenous fluids are immediately administered and a surgeon is called in to repair the artery. He begins by making an incision through the skin and subcutaneous tissue just below the clavicle, then cuts the clavicular head of the pectoralis major muscle and retracts it downward to obtain sufficient exposure of the area. He next encounters a partially severed muscle running downward and medially from the coracoid process. He divides the remaining fibers of the muscle and has you retract it downward. This exposes a bloody fat-filled space full of vessels and nerves. Postoperative examination revealed that the medial border and inferior angle of the left scapula became unusually prominent (projected posteriorly) when the arm was carried forward in the sagittal plane, especially if the patient pushed with outstretched arm against heavy resistance (e.g., a wall). What muscle must have been denervated during the axillary dissection?

Serratus anterior muscle ------------- Serratus anterior, innervated by the long thoracic nerve, draws the scapula forward. If it is denervated, there is no muscle to oppose the motion of the trapezius which is elevating and retracting the scapula. The medial border of the scapula falls away from the posterior chest wall and begins to look like an angel's wing. This is termed a "winged scapula." A winged scapula commonly occurs after an injury to the long thoracic nerve, which runs on the superficial surface of serratus anterior and is particularly vulnerable to trauma. The long thoracic nerve contains contributions from C5, 6, and 7, so remember the saying "C5, 6, and 7 keep the wings from heaven." This is a classic scenario to remember!

A man is in an auto accident and sustains several injuries, among them are: 1. Skin lacerations: on the back of his head in the occipital area, on his chest just above the nipple, on the lateral side of his arm, lateral forearm at midlength, dorsal hand between his thumb and index finger 2. Abrasions and contusions (bruises) about his right shoulder 3. A fractured right radius near its distal end While you are stitching up his hand, he notes that you did not have to give him an anesthetic since the area between his thumb and index finger on the dorsal side was already numb. Which nerve must have been injured (most likely by the fracture of his wrist) for this area to be numb?

Superficial radial nerve ------------------- The superficial radial nerve provides cutaneous innervation to the radial side of the dorsum of the hand for the first 2 1/2 digits. An injury to this nerve would correlate to the loss of sensation between the thumb and index finger on the dorsum of the hand. The lateral antebrachial cutaneous innervates the lateral anterior side of the forearm--it is a branch of the musculocutaneous nerve. The medial antebrachial cutaneous nerve comes off the medial cord of the brachial plexus--it innervates the medial anterior side of the forearm. The median nerve provides cutaneous branches that innervate the radial side of the palmar or volar surface of the hand for the first 3 1/2 digits. Finally, the superficial ulnar nerve innervates the ulnar side of the hand on both the palm and the dorsum, covering the final 1 1/2 fingers on the volar surface and 2 1/2 fingers on the dorsum.

The clavipectoral fascia is penetrated by which artery?

Thoracoacromial artery ---------------- The thoracoacromial artery pierces the clavipectoral fascia before giving off its four branches: pectoral, clavicular, deltoid, and acromial. It supplies pectoralis major, pectoralis minor, the deltoid muscle, and the acromioclavicular joint. It is a branch off of the axillary artery. The axillary artery and all its other branches, including the anterior circumflex humoral and subscapular arteries, run deep to the clavipectoral fascia. The thoracodorsal artery is a branch of the subscapular artery which also runs deep to the fascia.

After trying to throw a curve ball, a pitcher lost sensation from the tip of the little finger. This indicates injury to which nerve?

Ulnar nerve ------------ The ulnar nerve innervates the medial 1.5 digits on the palmar surface of the hand, and 2.5 digits on the dorsal side. So, this is the nerve responsible for innervating the tip of the little finger. The radial nerve innervates the dorsal side of the lateral 2.5 digits, but does not innervate the tips of these fingers. The median nerve, which innervates the palmar side of the lateral 3.5 digits, also innervates the fingertips of these 3.5 fingers. The musculocutaneous nerve does not provide cutaneous innervation to the skin, but its branch, the lateral antebrachial cutaneous nerve, innervates the lateral skin of the forearm. The medial antebrachial cutaneous nerve innervates the medial skin of the forearm - this nerve is a direct branch of the medial cord of the brachial plexus.