LEARNING OBJECTIVES
Unit II - Trunk
Clinical Content
1. Describe the most likely surrounding structures to be injured in a fracture of the 1st rib, a middle rib or a lower rib.
-“The short broad 1st rib, posteroinfreior to the clavicle, is rarely fractured because of its protected position (it cannot be palpated). When it is broken, however, structures crossing its superior aspect may be injured, including the brachial plexus of nerves and subclavian vessels that serve the upper limb. The middle ribs are most commonly fractured. Rib fractures usually result from blows or from crushing injuries. The weakest part of a rib is just anterior to its angle; however, direct violence may fracture a rib anywhere, and its broken end may injure internal organs such as a lung and/or the spleen. Fractures of the lower ribs may tear the diaphragm and result in a diaphragmatic hernia. Rib fractures are painful because the broken parts move during respiration, coughing, laughing, and sneezing.” (COA p 83)
2. Define "flail chest" and describe the paradoxical movement of the chest wall that often accompanies this injury.
-“Multiple rib fractures may allow a sizable segment of the anterior and/or lateral thoracic wall to move freely. The loose segment of the wall moves paradoxically (inward on respiration and outward on expiration). Flail chest is an extremely painful injury and impairs ventilation, thereby affecting oxygenation of the blood. During treatment, the loose segment may be fixed by hooks and/or wires so that it cannot move.” (COA p 83)
3. Name the most common site of a sternal fracture and describe the possible consequences of such an injury including myocardial contusion, cardiac rupture, cardiac tamponade and lung injury.
“Despite the subcutaneous location of the sternum, sternal fractures are not common. Crush injuries can occur after traumatic compression of the thoracic wall in automobile accidents when the driver’s chest is forced into the steering column, for example. The installation and use of airbags in vehicles has reduced the number sternal fractures. A fracture of the sternal body is usually a comminuted fracture (a break resulting in several pieces). Displacement of the bone fragments is uncommon because the sternum is invested by deep fascia (fibrous continuities of the radiate sternocostal ligaments); and the sternal attachments of the pectoralis major muscles. The most common site of sternal fracture in elderly people is at the sternal angle, where the manubriosternal joint has fused. The fracture results in dislocation of the manubriosternal joint.
“The concern in sternal injuries is not primarily for the fracture itself but for the likelihood of heart injury (myocardial contusion, cardiac rupture, tamponade) or lung injury. The mortality (death rate) associated with sternal fractures is 25-45%, largely owing to these underlying injuries. Patients with sternal contusion should be evaluated for underlying visceral injury.” (COA p 84)
4. Describe the weak areas of the pelvic bones that are most commonly fractured and name the clinical implications of a pubo-obturator fracture.
-“Anteroposterior compression of the pelvis occurs during crush accidents (as when a heavy object falls on the pelvis). This type of trauma commonly produces fractures of the pubic rami. When the pelvis is compressed laterally, the acetabula and ilia are squeezed toward each other and may be broken.
Fractures of the bony pelvic ring are almost always multiple fractures or a fracture combined with a joint dislocation. To illustrate this, try breaking a pretzel ring at just one point. Some pelvic fractures result from the tearing away of bone by the strong ligaments associated with the sacroiliac joints.
“Pelvic fractures can result from direct trauma to the pelvic bones, such as occurs during an automobile accident, or be caused by forces transmitted to these bones from the lower limbs during falls on the feet. Weak areas of the pelvis, where fractures often occur, are the pubic rami, the acetabula (or the area immediately surrounding them), the region of the sacroiliac joints, and the alae of the ilium.
“Pelvic fractures may cause injury to pelvic soft tissues, blood vessels, nerves, and organs. Fractures in the pubo-obturator area are relatively common and are often complicated because of their relationship to the urinary bladder and urethra, which may be ruptured or torn.
“Falls on the feet or buttocks from a high ladder may drive the head of the femur through the acetabulum into the pelvic cavity, including pelvic viscera, nerves, and vessels. In individuals younger than 17 years of age, the acetabulum may fracture through the triradiate cartilage into its three developmental parts or the bony acetabular margins may be torn away.” (COA p 335)
5. Describe the most common path/route of lymphatic drainage from the following cancers:
(A) Breast: “Breast cancer typically spreads by means of lymphatic vessels (lymphogenic metastasis), which carry cancer cells from the breast to the lymph nodes, chiefly those in the axilla. The cells lodge in the lymph nodes, producing nests of tumor cells (metastases). Abundant communication among lymphatic pathways and among axillary, cervical, and parasternal nodes may also cause metastases from the breast to develop in the supraclavicular lymph nodes, the opposite breast, or the abdomen. Because most of the lymphatic drainage of the breast is to the axillary lymph nodes, they are the most common site of metastasis from a breast cancer. Enlargement of these palpable nodes suggests the possibility of breast cancer and may be key to early detection. However, the absence of enlarged axillary lymph nodes is no guarantee that metastasis from a breast cancer has not occurred because the malignant cells may have passed to other nodes, such as the infraclavicular and supraclavicular lymph nodes.” (COA p 104)
(B) Bronchogenic: “The term bronchogenic carcinoma was once a specific designation for cancer arising in a bronchus—usually squamus- (oat) or small-cell carcinoma(cancer)—but now the term refers to any lung cancer. … The primary tumor, observed radiologically as an enlarging lung mass, metastasizes early to the bronchopulmonary lymph nodes and subsequently to other thoracic lymph nodes. … Often the lymph nodes superior to the clavicle—the supraclavicular lymph nodes—are enlarged when bronchogenic carcinoma develops owing to metastases of cancer cells from the tumor. Consequently, the supraclavicular lymph nodes were once referred to as sentinel lymph nodes because their enlargement alerted the physician to the possibility of malignant disease in the thoracic and/or abdominal organs. More recently, the tern sentinel lymph node has been applied to a node or nodes that first receive lymph drainage from a cancer-containing area, regardless of location, following injection of blue dye containing radioactive tracer.” (COA p 125)
(C) Ovarian: Ovaries typically drain to the Lumbar node group (COA p 401)
(D) Testicular: “metastasizes initially to the retroperitoneal lumbar lymph nodes, which lie just inferior to the renal veins. Subsequent spread may be to mediastinal and supraclavicular nodes.” (COA p 215) (different drainage than that of scrotum)
(E) Sigmoid colon: The sigmoid colon typically drains to the Inferior mesenteric node group (COA p 401)
(F) Rectal: Superiormost rectum drains to Inferior mesenteric, Superior rectum drains to Pararectal (then to Inferior mesenteric), Inferior rectum drains to Sacral (and then to/or straight to Internal iliac) (COA p 401)
(G) Anal: Anal canal (above pectinate line drains to Internal iliac). Anal canal (below pectinate line drains to superficial inguinal). (COA p 401)
6. Name the nerve injury most commonly associated with paralysis of a hemidiaphragm and describe normal and paradoxical diaphragm movements at rest and with inspiration.
-“Paralysis of half of the diaphragm (one dome or hemidiaphragm) because of injury to its motor supply from the phrenic nerve does not affect the other half because each dome has a separate nerve supply. One can detect paralysis of the diaphragm radiologically by noting its paradoxical movement. Instead of descending as it normally would during inspiration owing to diaphragmatic contraction, the paralyzed dome ascends as it is pushed superiorly by the abdominal viscera that are being compressed by the active contralateral dome. Instead of ascending during expiration, the paralyzed dome descends in response to the positive pressure in the lungs.” (COA p 85)
7. Describe the desired location, procedure and most common reasons a clinician performs the following types of nerve blocks:
(A) Intercostal: “Local anesthesia of an intercostals space is produced by injecting an anesthetic agent around the intercostals nerves between the paravertebral line and the area of required anesthesia. This procedure, an intercostals nerve block, involves infiltration of the anesthetic around the intercostals nerve trunk and its collateral branches. The term block indicates that the nerve endings in the skin and transmission of impulses through the sensory nerves carrying information about pain are interrupted (blocked) before the impulses reach the spinal cord and brain. Because any particular area of skin usually receives innervations from two adjacent nerves, considerable overlapping of contiguous dermatomes occurs. Therefore, complete loss of sensation usually does not occur unless two or more intercostals nerves are anesthetized.” (COA p 97)
(B) Pudendal: “To relieve pain during childbirth, pudendal nerve block anesthesia may be performed by injecting a local anesthetic agent into the tissues surrounding the pudendal nerve. The injection is made where the pudendal nerve crosses the lateral aspect of the sacrospinous ligament, near its attachment to the ischial spine. The needle may be passes through the overlying skin or, more commonly perhaps, through the vagina parallel to the palpating finger. Because the fetus’s head is usually stationed within the lesser pelvis at this stage, it is important that the physician’s finger is always positioned between the needle tip and the baby’s head during the procedure.” (COA p 433) “A pudendal nerve block is a peripheral nerve block that provides local anesthesia over the S2-S4 dermatomes (the majority of the perineum) and the inferior quarter of the vagina. It does not block pain from the superior birth canal (uterine cervix and superior vagina), so the mother is able to feel uterine contractions.” (COA p 398)
8. Describe the location, most common causes and clinical implications of the following hernias:
(A) Umbilical: “Most hernias occur in the inguinal, umbilical and epigastric regions. Umbilical hernias are common in newborns because the anterior abdominal wall is relatively weak in the umbilical ring, especially in low-birth-weight infants. Umbilical hernias are usually small and result from increased intraabdominal pressure in the presence of weakness and incomplete closure of the anterior abdominal wall after ligation of the umbilical cord at birth. Herniation occurs through the umbilical ring. Acquired umbilical hernias occur most commonly in women and obese people. Extraperitoneal fat and/or peritoneum protrude into the hernia sac. The lines along which the fibers of the abdominal aponeuroses interlace are also potential sites of herniation. Occasionally, gaps exist where these fiber exchanges occur—for example, in the midline or in the transition from aponeurosis to rectus sheath. The gaps may be congenital, the result of the stresses of obesity and aging, or the consequence of surgical or traumatic wounds.” (COA p 197)
(B) Hiatal (para-esophageal and sliding types): “A hiatal (hiatus) hernia is a protrusion of part of the stomach into the mediastinum through the esophageal hiatus of the diaphragm. The hernias occur most often in people after middle age, possibly because of weakening of the muscular part of the diaphragm and widening of the esophageal hiatus. Although clinically there are several types of hiatal hernias, the two main types are paraesophageal hiatal hernia and sliding hiatal hernia.
“In the less common paraesophageal hiatal hernia, the cardia remains in its normal position. However, a pouch of peritoneum, often containing part of the fundus, extends through the esophageal hiatus anterior to the esophagus. In these cases, usually no regurgitation of gastric contents occurs because the cardial orifice is in its normal position.
“In the common sliding hiatal hernia, the abdominal part of the esophagus, the cardia and parts of the fundus of the stomach slide superiorly through the esophageal hiatus into the thorax, especially when the person lies down or bends over. Some regurgitation of stomach contents into the esophagus is possible because clamping action of the right crus of the diaphragm on the inferior end of the esophagus is weak.” (COA p 254)
(C) Congenital diaphragmatic: “In congenital diaphragmatic hernia (CDH), part of the stomach and intestine herniated through a large posterolateral defect (foramen of Bochdalek) in the region of the lumbocostal trigone of the diaphragm. Herniation almost always occurs on the left owing to the presence of the liver on the right. This type of hernia results from the complex development of the diaphragm. Posterolateral defect of the diaphragm is the only relatively common congenital anomaly of the diaphragm, occurring approximately once in 2200 newborn infants. With abdominal viscera in the limited space of the prenatal pulmonary cavity, one lung (usually the left lung) does not have room to develop normally or to inflate after birth. Because of the consequent pulmonary hypoplasia, the mortality rate in these infants is high (approximately 76%). (COA p 317)
(D) Inguinal (direct and indirect): “The majority of abdominal hernias occur in the inguinal region. Inguinal hernias account for 75% of abdominal hernias. These herniations occur in both sexes but most inguinal hernias (approximately 86%) occur in males because of the passage of the spermatic cord through the inguinal canal.
“An inguinal hernia is a protrusion of parietal peritoneum and viscera, such as the small intestine, through a normal or abnormal opening from the cavity in which they belong. Most hernias are reducible, meaning they can be returned to their normal place in the peritoneal cavity by appropriate manipulation. The two types of inguinal hernias are direct and indirect inguinal hernias. More than two thirds are indirect hernias.
“Normally, most of the processus vaginalis obliterates before birth, except for the distal part that forms the tunica vaginalis of the testis. The peritoneal part of the hernia sac of an indirect inguinal hernia is formed by the persisting processus vaginalis. If the entire stalk of the processus vaginalis persists, the hernia extends into the scrotum superior to the testis, forming a complete indirect inguinal hernia.
“The superficial inguinal ring is palpable superolateral to the pubic tubercle by invaginating the skin of the upper scrotum with the index finger. The examiner’s finger follows the spermatic cord superolaterally to the superficial inguinal ring. If the ring is dilated, it may admit the finger without causing pain. Should a hernia be present, a sudden impulse is felt either against the tip or pad of the examining finger when the patient is asked to cough. However, because both inguinal hernia types exit the superficial ring, palpation of an impulse at this site does not discriminate type.