In an emergency tracheotomy, the cricothyroid membrane is incised in order to establish a direct airway for the patient. This procedure is also called a cricothyrotomy or cricothyroidotomy, and it is used as a last resort to circumvent upper airway obstructions. The cricothyroid membrane is an important component of the conus elasticus, which is composed of the vocal ligaments, median cricothyroid membrane, and lateral cricothyroid membranes. The cricothyroid membrane is the perfect location to perform an emergency tracheotomy because of several nearby palpable landmarks, and it is located below the (true) vocal folds, which serve as the main inspiratory sphincter of the larynx. Do not confuse the emergency tracheotomy with a tracheostomy, which is a procedure performed in a hospital setting and involves surgically creating a hole in the cartilaginous rings of the trachea. Choice A (Cricoid cartilage) is incorrect. Due to the thickness of the cricoid cartilage, incising through this cartilage would be diffi cult outside the hospital setting. Moreover, an incised cricoid cartilage would need surgical intervention to heal due to its lack of blood supply. Moreover, damaging the cricoid cartilage would be detrimental to the integrity of the larynx and the laryngeal skeleton. Choice B (Thyrohyoid membrane) is incorrect. Though it is easily palpated due to its position above the laryngeal prominence (or the “Adam’s apple”), the thyrohyoid membrane is located between vertebral levels C3 and C4 and may not establish a direct airway. To combat against an upper airway obstruction, the cricothyroid membrane (between vertebral levels C5 and C6) would be a better option. Damage to the thyrohyoid membrane could also compromise the superior laryngeal artery and the internal branch of the superior laryngeal nerve, which pierce this membrane to enter the larynx. Choice D (Tracheal rings) is incorrect. In a tracheostomy, a hole is created surgically in the cartilaginous rings of the trachea. However, this procedure is usually performed in a hospital setting under sterile conditions. Damage to the thyroid gland and infrahyoid muscles can easily occur if a tracheostomy is not performed correctly. Incising the cricothyroid membrane would be a much easier means of establishing an airway, especially considering the emergency conditions surrounding this patient’s choking incident. Choice E (Isthmus of the thyroid gland) is incorrect. Cutting through the isthmus of the thyroid gland would not establish an airway for this patient, so this option can be easily eliminated. Due to its location at the seventh cervical vertebra, this glandular tissue is often transected or resected during a tracheostomy, when the tracheal rings are incised. However, a tracheostomy is performed in a hospital setting under sterile conditions.

16) A pregnant woman is in a car accident and goes into premature labor. Her fetus is approximately 24 weeks in gestation. Her physicians administer her steroids and try to delay the birth of her baby. The survival rate of a premature baby rises signifi cantly if the baby can reach 28 weeks gestation mainly due to the maturation of the lungs. What stage of lung maturation are the doctors hoping to reach, in which the blood-air barrier is beginning to be established?

The simple cuboidal epithelium within the terminal sacs differentiates into pneumocytes within the terminal sac period. The rapidly proliferating capillary network makes intimate contact with the terminal sacs, and the blood-air barrier is established with Type I pneumocytes (or alveolar epithelial cells). These events take place in the terminal sac period, which runs from embryonic week 24 until birth and are crucial for the survival of an infant born prematurely. Administration of steroids to the infant in utero can promote lung maturation by increasing the proliferation of Type II pneumocytes (or alveolar epithelial cells), which secrete surfactant, a fl uid capable of decreasing the surface tension at the air-alveolar interface. Due to the terminal sac period of lung maturation, a premature infant’s survival rate will increase considerably from week 24 to 28 as the bloodair barrier continues to be established. Choice A (Embryonic period) is incorrect. At approximately 4 weeks of gestation, the respiratory diverticulum, or lung bud, begins to arise from the ventral wall of the foregut. Two longitudinal tracheoesophageal ridges fuse in the midline to form the tracheoesophageal septum, which separates the lung bud away from the foregut, specifi cally the esophagus, forming the trachea. The distal end of the trachea divides into two lateral bronchial buds. At the beginning of week 5, the bronchial buds elongate to form the primary (left and right main stem) bronchi, which further divide into the secondary bronchi. Choice B (Pseudoglandular period) is incorrect. The pseudoglandular period occurs from week 5 to 16 of gestation. During this period of lung maturation, the terminal bronchioles, which were established in the embryonic period of lung development, continue to divide to establish respiratory bronchioles and alveolar ducts. The vascular supply to the lungs also increases; however, respiration is not possible until there are enough capillaries within the lungs to enable suffi cient gas exchange. Adequate gas exchange is not possible until the terminal sac period is reached at approximately the seventh month of gestation. Choice C (Canalicular period) is incorrect. The canalicular period of lung maturation occurs from week 16 to 26 of gestation. During this period of lung development, the terminal sacs (primitive alveoli) form, and capillaries within the lung tissue begins to establish close contact with the primitive alveoli. However, respiration is not possible until the terminal sac period when an adequate supply of capillaries exist to enable suffi cient gas exchange. Adequate gas exchange is not possible until the seventh month of gestation. Choice E (Alveolar period) is incorrect. The alveolar period of lung maturation continues from month 8 of gestation and/ or birth until well into childhood. During this period of lung development, the number of mature alveoli within the lungs continues to increase in number and the blood-air barrier is now well established. However, it is during the terminal sac period of lung development (week 26–birth) when adequate gas exchange is established, making respiration possible in a premature infant.

17) A 12-year-old girl is examined by a school nurse who notices the girl’s right scapula is more prominent than the left, her head is not centered directly over the pelvis, and her right hip is raised and more prominent. When the girl is asked to bend forward at the waist, the nurse observes asymmetry of the trunk. Which of the following diagnoses is most likely?

Scoliosis (G: crookedness) is abnormal lateral and rotational curvature of the spine that may present with uneven hips, shoulders, and rib cage, a head that is not centered over the pelvis, the entire body leaning to one side, back pain, and/or fatigue. The given AnteriorPosterior (AP) X-ray shows an S-shaped curvature of the spine or vertebral column in this patient. In this X-ray, no apparent vertebral anomaly is apparent, so the diagnosis is most likely adolescent idiopathic scoliosis, which has an onset of 10 to 18 years of age and has no known cause. Most cases of adolescent idiopathic scoliosis (with curvatures of less than 20 degrees) require no treatment; however, if the curvature goes above 25 degrees, a back brace can be implemented to slow the progression of scoliosis. Choice B (Lordosis) is incorrect. Lordosis (G: bending backward) is an anteriorly convex curvature of the vertebral column (spine). The cervical and lumbar vertebral curvatures are normally lordotic; however, excessive lordotic curvature (also called hollow back, swayback, and saddleback) can be caused by tight lower back muscles, excessive abdominal fat, and pregnancy. Excessive lordosis can lead to lower back pain and can be treated with strengthening of the abdominal muscles and hamstrings. Choice C (Kyphosis) is incorrect. Kyphosis (G: hump-back) is an anteriorly concave curvature of the vertebral column (spine). The thoracic and sacral vertebral curvatures are normally kyphotic; however, deformities of the spine, due to degenerative arthritis, osteoporosis with compression fractures of the vertebrae, trauma, and developmental problems, can lead to excessive kyphotic curvature (or hunchback). Excessive kyphosis can cause pain and breathing diffi culties. The given lateral X-ray shows an example of abnormal kyphotic curvature of the lumbar spine due to benign compression fractures of the L1 and L3 vertebrae secondary to osteoporosis. This disease is characterized by compromised bone strength and decreased bone mass. The affected L1 and L3 vertebrae depict an anterior wedging deformity, which would cause the patient to appear shorter (lose height). Choice D (Osteoporosis) is incorrect. Osteoporosis is a disease characterized by compromised bone strength and decreased bone mass, which can lead to an increased rate of fracture in the vertebral column, the mid-forearm, and more frequently the proximal femur resulting in hip fractures. Women are four times more likely to receive the prognosis of osteoporosis, with approximately 25% of women between 65 and 85 years old being diagnosed with osteoporosis. Due to the age of this 14-year-old patient and the fi ndings of the nurse, osteoporosis is not likely. Choice E (Osteoarthritis) is incorrect. Osteoarthritis (or degenerative arthritis) erodes the articular cartilage in primarily weight-bearing joints. Because this type of arthritis is found in older populations, this diagnosis is not likely in this 14-year-old patient, especially due to the symptoms noted by the nurse.

This plain fi lm of the lateral knee indicates an avulsion fracture of the tibial tuberosity (white arrowhead), which is the insertion site for the quadriceps femoris muscles (rectus femoris and the vastus muscles [lateralis, medialis, and intermedius]) via the patellar ligament. Sudden, powerful muscle actions may cause avulsion fractures of the attachments of muscles. In this case, the push out of the starting blocks involves sudden, powerful extension of the right knee, which is the main action of the quadriceps. Because of the insertion onto the tibial tuberosity (via the patella), the force of the contraction of the quadriceps muscles may avulse the tibial tuberosity off the anterior surface of the tibia, resulting in the fragmented tibial tuberosity (white arrow), being pulled superiorly above the knee joint into the anterior thigh. The inability to straighten the leg refl ects the loss of extension of the knee from detachment of the quadriceps. Choice A (Gastrocnemius) is incorrect. The gastrocnemius is included in the posterior superfi cial compartment of the leg. It lies across the posterior aspect of the knee and contributes to fl exion of that joint. Because it inserts into the calcaneal tendon (tendo calcaneus; Achilles tendon), contraction of the gastrocnemius may cause an avulsion fracture of the calcaneal tuberosity. However, an avulsion fracture of the tibial tuberosity was shown on the given radiograph. Choice B (Tibialis anterior) is incorrect. The tibialis anterior is a member of the anterior compartment of the leg. It has an extensive origin from the lateral condyle and upper half of the lateral surface of the tibia and the interosseous membrane of the leg, and it crosses the anterior aspect of the ankle to insert onto the dorsum of the foot, thus producing dorsifl exion and inversion of the foot. It is commonly involved in the painful condition of shin splits. Choice C (Adductor magnus) is incorrect. This muscle is contained in the medial (adductor) compartment of the thigh. It runs from the ischial tuberosity to an extensive insertion along the linea aspera, medial supracondylar line, and adductor tubercle of the femur. It acts to adduct and fl ex the hip. Choice E (Semitendinosus) is incorrect. This hamstring muscle is part of the posterior compartment of the thigh. It originates from the ischial tuberosity and inserts via its long cord-like tendon onto the medial side of the proximal tibia, acting to extend the hip and flex the knee.

19) A 17-year-old boy comes to the emergency room after a hard fall onto the lateral aspect of his left shoulder during a high school basketball game. He complains of generalized pain during shoulder motion. On physical examination, the distal end of the clavicle is prominent and distinctly palpable. Radiological fi ndings confi rm the diagnosis of a severe (grade 3) shoulder separation. Which of the following features is a component of this condition?

“Shoulder separation” describes a dislocation of the acromioclavicular joint. In its most severe form (grade 3), the condition includes a tearing of both the intrinsic acromioclavicular ligament and the extrinsic coracoclavicular ligament. As a result, the scapula separates from the clavicle and falls away due to the weight of the upper limb. Thus, the distal end of the clavicle is prominent. Choice A (Dislocated head of the humerus) is incorrect. Dislocations of the GH joint easily occur inferiorly due to its lack of muscular and ligamentous support. Thus, damage to the axillary nerve often occurs following inferior displacment of the head of humerus from the GH joint. However, the acromioclavicular joint, which is more proximal, was injured in this patient. Dislocations of the glenohumeral joint in other directions are more diffi cult (but not impossible) because of the support of the rotator cuff muscles (anteriorly and posteriorly) and the coracoacromial arch (superiorly). Choice C (Fractured clavicle) is incorrect. Radiological imaging would have detected a fractured clavicle, but these tests confi rmed a shoulder separation and not a fractured clavicle. Choice D (Dislocated sternal end of the clavicle) is incorrect. Due to its intrinsic strength, dislocation of the sternoclavicular (SC) joint is rare. Most dislocations of the SC joint occur in persons less than 25 years of age following a fracture of the epiphysial plate of the clavicle. The epiphysis at the proximal end of the clavicle does not close until approximately age 25. Though this patient was under the age of 25, his injury was localized to the acromioclavicular joint. Choice E (Torn anterior glenohumeral [GH] ligament) is incorrect. Three GH ligaments reinforce the anterior part of the joint capsule; however, the GH joint was not involved in this patient.

20) A 1-year-old girl is brought to the clinic for a routine checkup. The child appears normal except for a dimpling of the skin in the lumbar region with a tuft of hair growing over the dimple. You reassure the mother that this condition is seen in 10% to 25% of births and normally has no ill effects. What is this relatively common condition that results from incomplete embryologic development?

Spina bifi da is a developmental condition resulting from incomplete fusion of the vertebral arches within the lumbar region. Spina bifi da occulta commonly presents asymptomatically with a tuft of hair and a small dimple in the overlying skin. More severe forms (spina bifi da cystica) are categorized into three types: Spina bifi da cystica with meningocele presents with protrusion of the meninges through the unfused vertebral arches. Spina bifi da with meningomyelocele is characterized by protrusion both of the meninges and CNS tissues and is often associated with neurologic defi cits. Rachischisis, also known as spina bifi da cystica with myeloschisis, results from a failure of neural folds to fuse and is characterized by protrusion of the spinal cord or spinal nerves and meninges.

The patient’s complaint is due to her case of hammer toes. Hammer toe can affect any toe but most commonly the second toe, then the third or fourth toes. It results most commonly from wearing shoes that are too short or shoes with heels that are too high. In hammer toe, the metatarsophalangeal joint is extended, the proximal interphalangeal joint is fl exed, and the distal phalanx points downward, looking like a hammer. Hammer toe can occur as a result of a bunion. Calluses, or painful corns, can form on the dorsal surface of the joints. In claw toe, both the proximal and distal interphalangeal joints are strongly fl exed, the result of muscle imbalance in the foot. Either hammer toe or claw toe can occur from arthritic changes. Pes cavus is the opposite of flat foot—the patient has a high, flexed plantar arch; it occurs as a result of hereditary motor and sensory neural problems. It is painful because of metatarsal compression.

22) A 23-year-old woman is admitted with severe abdominal pain, nausea, and vomiting. History taking shows that the pain is acute and has been constant for 4 days. The pain began in the epigastric region and radiated bilaterally around the chest to just below the scapulae. Currently the pain is localized in the right hypochondrium. A CT scan examination reveals calcifi ed stones in the gallbladder. Which of the following nerves is carrying the afferent fi bers of the referred pain?