Lippincott Chapter 1
Which of the following is true of a median plane of the hand? (A) It becomes a horizontal plane when the hand is medially rotated 90 degrees. (B) It becomes a coronal plane when the brachium (upper arm) is laterally rotated 90 degrees and abducted 90 degrees. (C) It is the same as a frontal plane. (D) It remains a median plane regardless of limb or body position. (E) It is oriented mediolaterally.
The answer is D: It remains a median plane regardless of limb or body position. All anatomical descriptions are relative to the anatomical position. Thus, no matter how the body is moved or postured, the observer must transpose the body into the anatomical position in order to make accurate, uniform descriptions. Choice A (It becomes a horizontal plane when the hand is medially rotated 90 degrees) is incorrect. All anatomical descriptions are relative to the anatomical position and do not change with movement. Choice B (It becomes a coronal plane when the brachium [upper arm] is laterally rotated 90 degrees and abducted 90 degrees) is incorrect. All anatomical descriptions are relative to the anatomical position and do not change with movement. Choice C (It is the same as a frontal plane) is incorrect. A median plane is a vertical anteroposterior plane that runs through the central (median) plane of the body, dividing it into equal-sized right and left parts. In the hand, the median plane runs longitudinally through the third (middle) digit. A frontal plane is a mediolateral plane that divides the body into anterior (front) and posterior (back) parts. Thus, the median plane is perpendicular to the frontal plane. Choice E (It is oriented mediolaterally) is incorrect. A median plane is a vertical anteroposterior plane that runs through the central (median) plane of the body, dividing it into equal-sized right and left parts. In the hand, the median plane runs longitudinally through the third (middle) digit. A mediolateral (frontal; coronal) plane divides the body into anterior and posterior parts. Thus, a mediolateral plane is perpendicular to the median plane.
During an exercise program, a physical therapist instructs her patient to fl ex his elbow. Which of the following terms describes the muscles that perform that desired action? (A) Agonists (B) Antagonists (C) Fixators (D) Proprioceptors (E) Synergists
The answer is A: Agonists. Muscles work in antagonistic pairings, that is, in opposition to one another. A muscle that performs a desired action is an agonist (prime mover). In this case, the muscles that act to fl ex the elbow are the agonists. Choice B (Antagonists) is incorrect. A muscle that acts in opposition to an agonist is an antagonist. During fl exion of the elbow, muscles that extend the elbow are the antagonists. Choice C (Fixators) is incorrect. Fixators are muscles that act to stabilize a joint other than the joint the agonist is affecting. In this case, muscles that hold the shoulder (glenohumeral) joint steady while elbow fl exion is occurring are the fi xators. Choice D (Proprioceptors) is incorrect. Proprioception is sense of movement and position within the muscle. Muscle spindles are the proprioceptive organs in skeletal muscles that register positional information (e.g., stretch). Choice E (Synergists) is incorrect. Synergists are muscles that act to aid agonists. They may complement the action of an agonist or act as fi xators at another joint. In this case, certain muscles that are weaker fl exors than the agonists are considered synergists because they may assist in fl exion to a lesser degree but are not the prime movers in producing fl exion.
Which of the following medical imaging techniques utilizes a beam of X-rays to transilluminate the body? (A) Computerized tomography (CT) (B) Magnetic resonance imaging (MRI) (C) Positron emission tomography (PET) (D) Ultrasonography (E) X-ray glasses
The answer is A: Computerized tomography (CT). CT scans are produced by rotating a beam of X-rays in an arc or a circle around the body, measuring the energy absorptions of the beam in different tissues in a computer, and converting the differential energy absorptions into images. CT scans are very similar to plain fi lm radiographs in that both use X-rays to image levels of radiodensity. However, CT images show radiographs that reconstruct horizontal sections of the body. Choice B (Magnetic resonance imaging [MRI]) is incorrect. MRIs are produced by pulsing radiowaves through the body in a scanner with a strong magnetic fi eld. The signals, generated from the patient, are related to excitation of magnetically aligned free protons in different tissues. These are reconstructed into images, similar to CT scans. MRIs can reconstruct anatomy in any plane and are better than CT for tissue differentiation. Choice C (Positron emission tomography [PET]) is incorrect. PET is a form of nuclear medicine imaging. In this modality, the positrons emitted from very short half-life isotopes are scanned and computed into images, which can be viewed as whole organs or horizontal sections. PET scans are used to monitor the physiological functioning of organs. Choice D (Ultrasonography) is incorrect. Ultrasounds are produced by recording and reconstructing ultrasonic waves refl ecting off tissues. A transducer in contact with the skin emits high frequency sound waves that pass through the body. These waves refl ect off different tissues as differing echoes. The echoes are collected as electrical signals, which are converted into images. Ultrasonography is less expensive than CT or MRI, highly portable, produces real-time images, and can demonstrate motion and sound (Doppler Effect). Choice E (X-ray glasses) is incorrect
In endochondral ossifi cation, bone replaces most of an initial cartilage model. Which of the following refers to the part of a bone ossifi ed from the primary ossifi cation center? (A) Diaphysis (B) Epiphysis (C) Metaphysis (D) Epiphyseal plate (E) Condyle
The answer is A: Diaphysis. The diaphysis of a bone is the region that ossifi es from the primary ossifi cation center. This area typically corresponds to the main body of the bone model, which develops from the periosteal bud. In long bones, the diaphysis forms the shaft of the bone. Choice B (Epiphysis) is incorrect. The epiphysis is the region that ossifi es from a secondary ossifi cation center. There are usually at least two epiphyses in long bones, one at each end of the diaphysis. Additional epiphyses may occur in other areas, where they are often related to sites of attachment of muscles or ligaments. Choice C (Metaphysis) is incorrect. The metaphysis is the expanded end of the diaphysis adjacent to the epiphysis. In adult long bones, the metaphysis forms a transitional area between those two areas. Choice D (Epiphyseal plate) is incorrect. The epiphyseal plate is the cartilaginous growth zone between the diaphysis and the epiphysis in growing bones. When the epiphyseal plate ossifi es, bone growth ceases and the diaphysis fuses with the epiphysis. In plain fi lm X-rays showing immature bones, the epiphyseal plate appears as a distinct radiolucent zone. In mature bone, the ossifi ed epiphyseal plate forms a dense seam that appears as a radiopaque epiphyseal line. Choice E (Condyle) is incorrect. A condyle is a rounded articular structure typically located at the epiphyseal end of a long bone (e.g., the head and capitulum of the humerus).
A physician discovers that his 72-year-old patient is leaking blood from a vessel that normally carries oxygen depleted blood. Which of the following vessels is most likely damaged? (A) Pulmonary trunk (B) Pulmonary veins (C) Abdominal aorta (D) Coronary arteries (E) Common carotid arteries
The answer is A: Pulmonary trunk. The right side of the heart receives oxygen-depleted blood from the systemic and coronary veins. The pulmonary trunk is the large artery that drains the right ventricle and sends that blood to the lungs for aeration. Remember, the critical difference between arteries and veins is that arteries carry blood away from the heart, whereas veins carry blood toward the heart. In the systemic vessels, arterial blood is typically oxygen-rich and venous blood oxygen-poor. However, in the pulmonary circuit, that oxygenation relationship is reversed. Choice B (Pulmonary veins) is incorrect. The pulmonary veins carry oxygen-rich blood from the lungs to the left atrium. They represent the fi nal step in the pulmonary circuit. Choice C (Abdominal aorta) is incorrect. The abdominal aorta conveys oxygenrich blood to supply the abdomen, pelvis and perineum, and lower limbs. Choice D (Coronary arteries) is incorrect. The coronary arteries convey oxygen-rich blood to supply the myocardium of the heart. Choice E (Common carotid arteries) is incorrect. The common carotid arteries convey oxygen-rich blood to supply structures of the brain, head, and neck.
Under normal conditions, lymphatic vessels periodically contain elevated amounts of fat droplets (chyle). The highest concentration of chyle is found in the lymphatics that drain which of the following organs? (A) Small intestine (B) Brain (C) Heart (D) Long bones (E) Spleen
The answer is A: Small intestine. Lymphatic capillaries (lacteals) collect the lipids and lipid-soluble vitamins absorbed by the gut and send that chyle through larger lymphatic vessels to the thoracic duct. Thus, the greatest concentration of chyle is found in the intestinal lymphatics (e.g., those draining the small intestine) following meals. Choice B (Brain) is incorrect. The brain and spinal cord (i.e., the entire central nervous system) do not have a lymphatic drainage. The surplus tissue fl uid from these organs drains into the cerebrospinal fl uid rather than into lymphatic vessels. Choice C (Heart) is incorrect. The heart does not produce chyle. Its lymphatic drainage is via standard lymph capillaries to
Synovial joints allow free movement between their bony elements. They are classifi ed into multiple subtypes according to the shape of the articulating surfaces and/or the degree of movement allowed. Which of the following synovial joint types permits multiaxial movement? (A) Pivot (B) Ball and socket (C) Condyloid (D) Saddle (E) Hinge
The answer is B: Ball and socket. Multiaxial movement occurs through several (more than two) axes or planes. In ball and socket joints, the rounded head of one bone moves in the concave socket of the other bone, such as the hip and shoulder (glenohumeral) joints. These highly mobile joints permit fl exion-extension, abduction-adduction, medial and lateral rotation, and other more subtle motions. Choice A (Pivot) is incorrect. In pivot joints (e.g., the median atlanto-axial joint between the atlas [C1] and the dens of the axis [C2]; the proximal radioulnar joint between the head of the radius and the proximal end of the ulna), a rounded process of one bone fi ts into a relatively shallow socket of the other bone and is held in place by a strong ligament. Pivot joints allow only rotation about a single axis, and these movements are uniaxial or single planar. Choice C (Condyloid) is incorrect. In condyloid joints, the rounded (condylar) end of one bone moves in the shallow concave end of the other bone, such as the metacarpophalangeal joints. Movement is biaxial (through two planes); however, one movement typically is dominant. Some authors make a case that condyloid joints may be multiaxial, depending on the degree of movement argued for in the third plane. Choice D (Saddle) is incorrect. In saddle joints, the ends of the articulating bones are both concave and form a saddle-like junction. The movement here is biaxial (through two planes). The carpometacarpal joint located at the base of the thumb is a prime example. Choice E (Hinge) is incorrect. In hinge joints, the rounded end of one bone fi ts into the concave end of the other. The lateral sides of the joint are reinforced with strong collateral ligaments so that movement is essentially limited to a hinge-like, uniaxial plane. The humeroulnar (elbow) joint is a hinge joint.
A radiologist orders a posteroanterior (PA) plain fi lm of the chest. This image should provide the greatest resolution of which of the following structures? (A) Transverse processes of vertebrae (B) Heart (C) Esophagus (D) Primary bronchi (E) Descending aorta
The answer is B: Heart. The PA plain fi lm is the standard radiographic view of the thorax, and probably the most commonly obtained medical image. In basic terminology, a PA radiograph is one in which the X-ray beam penetrates from the patient's posterior side to the anterior side, as shown in the given illustration. The X-ray projector is located posterior to the patient, and the X-ray fi lm is positioned anterior. The part of the body under study should be as close as possible to the X-ray fi lm in order to optimize the resolution of that part and minimize magnifi cation artifacts. Thus, in the PA orientation, the heart is closest to the X-ray fi lm and appears sharper than the other structures in question. Choice A (Transverse processes of the vertebrae) is incorrect. In the PA orientation, the vertebral column (being in the posterior aspect of the body) is further away from the X-ray fi lm. Also, the vertebrae are in line with several other overlapping structures
A 17-year-old boy engages in an intensive weight-lifting program to build muscle strength. The growth of his muscles is the result of which of the following processes? (A) Atrophy (B) Hypertrophy (C) Hyperplasia (D) Tonus (E) Shunting
The answer is B: Hypertrophy. Postnatal growth in size of skeletal muscles in response to exercise is the result of increased size (hypertrophy) of existing muscle fi bers rather Lambert_Chap01.indd 10 Lambert_Chap01.indd 1
A man exhibits anhydrosis (lack of sweating) and erythema (fl ushing) on his chest due to loss of sympathetic innervation. A thorough neurological analysis reveals dysfunction of presynaptic (preganglionic) sympathetic nerve cell bodies. Which of the following sites is most likely damaged in this patient? (A) Brainstem (B) Lateral gray horn of the spinal cord (C) Sympathetic chain ganglia (D) Prevertebral ganglia (E) Dorsal root ganglia
The answer is B: Lateral gray horn of the spinal cord. Presynaptic sympathetic neurons originate in the pronounced lateral gray horn of the spinal cord, from spinal segments T1-L2 (or L3). Thus, the sympathetic division is described as having a thoracolumbar outfl ow. It is the sympathetic nerve fi bers that are damaged in this patient, leading to the anhydrosis and erythema. Choice A (Brainstem) is incorrect. Nuclei-housing presynaptic parasympathetic neurons are associated with four cranial nerve outfl ow tracts in the brainstem: Oculomotor nerve (CN III); Facial nerve (CN VII); Glossopharyngeal nerve (CN IX); Vagus nerve (CN X). Because parasympathetic fi bers emerge from both cranial and sacral levels of the central nervous system, this division is described as having a craniosacral outfl ow. Choice C (Sympathetic chain ganglia) is incorrect. The sympathetic chain ganglia, strung along the lateral sides of the vertebral column, contain the cell bodies of postsynaptic sympathetic neurons. These neurons project axons to the head and neck, body wall and limbs, and thoracic viscera. Choice D (Prevertebral ganglia) is incorrect. Prevertebral (preaortic) ganglia are located along the anterior aspect of the vertebral column and house mainly the cell bodies of postsynaptic sympathetic neurons. These cells project their axons to the abdominopelvic viscera and the external genitalia. Choice E (Dorsal root ganglia) is incorrect. Dorsal root (spinal) ganglia, located on each dorsal root of a spinal nerve, contain the cell bodies of general sensory (general somatic afferent; GSA) and visceral sensory (general visceral afferent; GVA) neurons. The axonal processes of these pseudounipolar cells originate as sensory receptors in the periphery and project to the dorsal grey horn in the spinal cord.
Bones are often classifi ed according to their shape and/or developmental pattern. Which of the following choices is an example of a fl at bone? (A) Humerus (B) Sternum (C) Hamate (D) Maxilla (E) Patella
The answer is B: Sternum. The sternum (breastbone) and the bones that form the cranial roof, or calvaria, are fl at bones. These bones are typically located subcutaneously and are easily accessible. The sternum is a notable fl at bone because it is Lambert relatively thick for this type of bone, and it is commonly used for collecting bone marrow. Choice A (Humerus) is incorrect. The humerus is a long bone. Long bones are usually elongated and tubular, with a distinct medullary (marrow) cavity. Long bones are characteristic of the limbs. Choice C (Hamate) is incorrect. The hamate is a short bone. Short bones do not have a medullary cavity. Short bones include the carpal bones of the wrist and the tarsal bones, located in the ankle. Choice D (Maxilla) is incorrect. The maxilla is an irregular bone, which makes up the "none-of-the-above" category. Irregular bones have shapes that are not readily classifi ed as long, short, or fl at. Examples of irregular bones include the facial bones (including the paired maxillae) and the vertebrae. Choice E (Patella) is incorrect. The patella (kneecap) is a sesamoid bone. This type of bone is formed within tendons. Sesamoid bones serve to protect tendons where they cross over joints and/or change the angle of tendons to improve their mechanical advantage at joints. The patella is the largest sesamoid bone. Other sesamoid bones are typically found at the bases of the thumb and the great toe.
Which of the following is a characteristic feature of the venous system? (A) The direction of blood fl ow in veins is away from the heart (B) Veins in the limbs tend to be double or multiple vessels (C) Veins are less abundant than arteries (D) The walls of veins are thicker than those of their companion arteries (E) Veins tend to spurt blood when cu
The answer is B: Veins in the limbs tend to be double or multiple vessels. The veins in the limbs tend to occur as two or more smaller vessels tightly surrounding their accompanying artery. This feature is especially true of the deep vessels, where the veins are denoted as accompanying veins (venae comitantes). This arrangement works as a physiological countercurrent heat exchange mechanism, in which outfl owing warmer arterial blood warms the infl owing cooler venous blood. Choice A (The direction of blood fl ow in veins is away from the heart) is incorrect. Regardless of any anatomical or physiological characteristics, veins always carry blood toward the heart. Conversely, arteries always carry blood away from the heart. This simple rule helps in interpreting issues with fetal-adult circulatory patterns and with many
Which of the following statements is true regarding the resultant imagery in standard CT (computerized tomography) fi lms? (A) Air appears white (B) Muscle appears black (C) Bone appears white (D) Fluids appear black (E) Fat appears white
The answer is C: Bone appears white. Both plain fi lm radiographs and CT scans utilize X-ray beams to penetrate the body and measure different levels of radiodensity. Thus, both techniques produce similar images. More radiodense tissue (e.g., compact bone) appears white, whereas less radiodense substances (e.g., air) appear black. Tissues of intermediate degrees of radiodensity appear as varying shades of gray. Choice A (Air appears white) is incorrect. Air is the least dense (most radiolucent) substance. Therefore, air appears black. Choice B (Muscle appears black) is incorrect. Muscle is composed of an intermediate density compared to the extremes of air, which appears black because it is the most radiolucent substance, and compact bone, which appears white because it is the most radiodense substance. Therefore, muscle would appear as a shade of gray in a standard CT scan. Choice D (Fluids appear black) is incorrect. Fluids are composed of an intermediate density compared to the extremes of air, which appears black because it is the most radiolucent substance, and compact bone, which appears white because it is the most radiodense substance. Therefore, fl uids would appear as a shade of gray in a standard CT
Assuming normal health and imaging conditions, which of the labeled structures in the given posteroanterior (PA) radiograph of the chest is the most radiopaque?
The answer is C: Coracoid process of the scapula. The image is a conventional plain fi lm radiograph of the thorax. This fundamental imaging technique utilizes a beam of X-rays to penetrate the body, producing an image of different degrees of light to dark on the X-ray fi lm located past the body. The degrees of light to dark correspond to differing densities of tissue mass. Tissue that is relatively dense in mass (e.g., compact bone) absorbs more X-rays than less dense tissue (e.g., fat). As a result, fewer X-rays reach the silver salt emulsion in the X-ray fi lm, and fewer grains of silver are developed when the fi lm is processed. The areas where less silver is developed appear more white on the fi lm and are referred to as "radiopaque". The areas where more silver is developed appear more black on the fi lm and are referred to as "radiolucent". Therefore, dense tissue (e.g., compact bone, dental enamel) appears white and is radiopaque. The least dense substance (air) appears black and is radiolucent. Tissues of intermediate densities (e.g., fat, fl uids, most organs, spongy bone) appear as varying shades of gray. In this radiograph, the coracoid process of the scapula (composed of both compact and spongy bone) is the densest of the labeled structures, is most radiopaque, and appears as a distinctly defi ned white image. Choice A (Right atrium) is incorrect. The right atrium produces an intermediate density, between the radiolucent lung and the radiopaque bone, so it appears on the X-ray as a shade of gray. Choice B (Right lung) is incorrect. Because the lung contains a large volume of air and is composed largely of spongy tissues, it typically appears black (radiolucent) on conventional plain fi lms. Choice D (Arch of the aorta) is incorrect. The arch of the aorta produces an intermediate density, between the radiolucent lung and the radiopaque bone, so it appears on the X-ray as a shade
In examining a radiograph of the right shoulder of a 32-year-old male car accident victim, the radiologist identifi es the head of the humerus located below the coracoid process of the scapula in a subcoracoid position. Which of the following terms best describes the condition of the humerus? (A) Avulsed (B) Comminuted (C) Dislocated (D) Reduced (E) Subluxated
The answer is C: Dislocated. The head of the humerus normally articulates with the glenoid fossa of the scapula to form the glenohumeral (shoulder) joint. Therefore, the subcoracoid position is abnormal. A dislocation is a complete displacement of the bones at a joint. In this case, the head of the humerus is completely removed from its normal position. Repositioning of the humerus may require anesthesia and/or muscle relaxants
A radiologist wishes to image the body in a plane parallel to both scapulae. Which of the following choices best describes the desired sectioning? (A) Horizontal section (B) Transverse section (C) Frontal section (D) Sagittal section (E) Oblique section
The answer is C: Frontal section. The scapulae (shoulder blades) lie across the back. An imaging plane passing parallel to both these bones divides the body into anterior (front) and posterior (back) parts. A frontal (coronal) section divides the body into anterior (front) and posterior (back) portions. It runs perpendicular to the median and horizontal planes. Choice A (Horizontal section) is incorrect. A horizontal section passes at right angles to both the median and coronal planes, dividing the body into superior (upper) and inferior (lower) parts. Choice B (Transverse section) is incorrect. A transverse section (cross section) passes perpendicular to the long axis of a structure. While often the same as a horizontal section, it is not always equivalent. For example, a transverse section through the foot is equivalent to a coronal (frontal) section, dividing the foot into anterior and posterior parts. However, a horizontal section of the foot divides it into superior and inferior parts, as shown in the given illustration. Choice D (Sagittal section) is incorrect. A sagittal section runs parallel to the median plane of the body, dividing it into unequal right and left parts. Choice E (Oblique section) is incorrect. Oblique sections run at offset angles from the median, coronal, and horizontal planes. Horizontal sections of the abdomen produce mostly oblique (not transverse) sections of the small intestine because of the coiled nature of the bowel.
Which of the following is an example of a cartilaginous joint? (A) Humeroulnar joint (B) Middle radioulnar joint (C) Intervertebral disc joint (D) Cranial sutural joint (E) Tibiotalar joint
The answer is C: Intervertebral disc joint. Three major classes of joints exist, based on the nature of the articulation: (1) Synovial, (2) Fibrous, and (3) Cartilaginous. In cartilaginous joints, the articulating bones are joined together by hyaline cartilage or fi brocartilage. The intervertebral discs are pads of largely fi brocartilage that bind together the bodies of adjacent vertebrae. Other examples include the pubic
A 65-year-old woman develops blood clots in her lower limbs. If one of these were to break loose and fl ow through the venous system, it would embed in capillaries in which of the following locations? (A) Brain (B) Kidneys (C) Lungs (D) Liver (E) Heart
The answer is C: Lungs. Vascular drainage of the lower limbs is through the systemic veins and into the right side of the heart. The right heart sends blood to the lungs, where the fi rst capillary beds are encountered. Thus, the clot (thrombus) would lodge in the capillary beds of the lungs, producing a thromboembolism. Choice A (Brain) is incorrect. Blood returning from the lower limbs must fi rst pass through the pulmonary circuit of the heart (through the lungs) and then into the cranial systemic arterial circuit in order to reach the brain. Choice B (Kidneys) is incorrect. Blood returning from the lower limbs again must fi rst pass through the pulmonary circuit of the heart (through the lungs) and into the descending aorta in order to reach the kidneys. Choice D (Liver) is incorrect. Venous blood entering the liver is derived from the drainage of the gut tube and spleen. This circuit constitutes the hepatic portal system. The systemic veins draining the lower limbs do not run through the hepatic portal system or liver. Choice E (Heart) is incorrect. Blood returning from the lower limbs must fi rst pass through the pulmonary circuit of the heart (through the lungs), then through the left side of the heart, and into the ascending aorta in order to enter the coronary arteries and the heart wall.
During removal of a neurogenic tumor in the posterior mediastinum, the indicated structure in the given diagram was damaged. What type of nerve fi bers were affected by this iatrogenic injury? X (A) Presynaptic sympathetic axons (B) Presynaptic parasympathetic axons (C) Postsynaptic sympathetic axons (D) Postsynaptic parasympathetic axons (E) Somatic motor axons
The answer is C: Postsynaptic sympathetic axons. The indicated structure is a gray ramus communicans. Gray rami communicantes are located along the entire length of the sympathetic chain, connecting sympathetic chain ganglia with individual spinal nerves. They convey postsynaptic sympathetic fi bers from the sympathetic chain to spinal nerves, for
A research scientist at a pharmaceutical company discovers a new drug that selectively blocks the release of norepinephrine from nerve endings. At which of the following sites would this drug have the greatest effect on normal synaptic transmission? (A) Somatic neuron motor end plates (B) Postsynaptic parasympathetic nerve terminals (C) Postsynaptic sympathetic nerve terminals (D) Synapses between presynaptic and postsynaptic parasympathetic neurons (E) Synapses between presynaptic and postsynaptic sympathetic neurons
The answer is C: Postsynaptic sympathetic nerve terminals. Postsynaptic sympathetic neurons typically release the neurotransmitter norepinephrine/noradrenaline from their endings, so the sympathetic division is described as a noradrenergic system. Blocking the release of norepinephrine would disrupt normal neurotransmission at these terminal sites. An important exception to this rule is that the postsynaptic sympathetic neurons supplying sweat glands typically release acetylcholine from their endings. Choice A (Somatic neuron motor end plates) is incorrect. The somatic motor neurons that supply skeletal muscle fi bers utilize acetylcholine as their neurotransmitter at motor end plates. Choice B (Postsynaptic parasympathetic nerve terminals) is incorrect. Postsynaptic parasympathetic neurons typically release acetylcholine as the neurotransmitter at their endings, so the parasympathetic division is described as a cholinergic system. Choice D (Synapses between presynaptic and postsynaptic parasympathetic neurons) is incorrect. Both sympathetic and parasympathetic divisions utilize acetylcholine as the neurotransmitter between their presynaptic and postsynaptic cells. Choice E (Synapses between presynaptic and postsynaptic sympathetic neurons) is incorrect. Both sympathetic and parasympathetic divisions utilize acetylcholine as the neurotransmitter between their presynaptic and postsynaptic cells.
A surgeon mistakenly lacerates the thoracic duct during lung surgery. Which of the following would be the immediate consequence of this iatrogenic action? (A) High blood pressure (B) Low blood pressure (C) Decreased immunity (D) Chylothorax (E) Lymphedema
The answer is D: Chylothorax. Because it is thin walled and often appears colorless, the thoracic duct may be diffi cult to recognize and is subject to accidental injury. If lacerated, lymph and chyle drain into the pleural cavity, creating a condition termed "chylothorax." If the thoracic duct requires ligation, lymph enters the venous system via alternative lymphatic vessels. Choice A (High blood pressure) is incorrect. Laceration of the thoracic duct does not in itself alter blood pressure relationships. Choice B (Low blood pressure) is incorrect. Laceration of the thoracic duct does not in itself alter blood pressure relationships. Choice C (Decreased immunity) is incorrect. Even though lymphocytes are produced by lymphatic organs and travel through lymph vessels, laceration of the thoracic duct does not result in compromised immunity. Again, the numerous alternative lymphatic drainage routes to the venous system offer effective lymph fl ow. Choice E (Lymphedema) is incorrect. Lymphedema (edema) is localized swelling caused by the buildup of tissue fl uid when lymph does not drain. Cutting the thoracic duct allows lymph to drain out into body cavities but not to accumulate within tissues. If the thoracic duct were ligated or obstructed, edema would result from back pooling of tissue fl uid.
A physician delivers an intramuscular injection into the lateral aspect of the shoulder. Which of the following sequences describes the correct order of tissue layers pierced by the needle, passing from superfi cial to deep? (A) Epidermis, dermis, superfi cial fascia, epimysium, deep fascia (B) Dermis, epidermis, superfi cial fascia, deep fascia, epimysium (C) Dermis, epidermis, superfi cial fascia, epimysium, deep fascia (D) Epidermis, dermis, superfi cial fascia, deep fascia, epimysium (E) Epidermis, superfi cial fascia, dermis, deep fascia, epimysium
The answer is D: Epidermis, dermis, superfi cial fascia, deep fascia, epimysium. The epidermis is the superfi cial cellular layer of the skin. The dermis is the deeper, dense connective tissue layer of the skin. The superfi cial fascia (subcutaneous tissue) is the fatty loose connective tissue layer that underlies the skin. The deep fascia is the relatively dense, fat-free connective tissue layer that lies deep to the skin and superfi cial fascia. The epimysium is a deep extension of the deep fascia that tightly invests the surface of individual muscles. Choice A (Epidermis, dermis, superfi cial fascia, epimysium, deep fascia) is incorrect. In this sequence, the epimysium incorrectly overlies the deep fascia. Choice B (Dermis, epidermis, superfi cial fascia, deep fascia, epimysium) is incorrect. Here, the dermis is incorrectly superfi cial to the epidermis. Choice C (Dermis, epidermis, superfi cial fascia, epimysium, deep fascia) is incorrect. Again, the dermis is incorrectly listed as the most superfi cial layer. Also, the epimysium incorrectly overlies the deep fascia. Choice E (Epidermis, superfi cial fascia, dermis, deep fascia, epimysium) is incorrect. In this sequence, the superfi cial fascia is incorrectly interposed
A 16-year-old boy crashes his mountain bike and suffers a fractured tibia. Which of the following damaged structures would most likely produce the acute pain emanating from the fractured tibia? (A) Nerves in compact bone (B) Nerves in trabecular bone (C) Surrounding muscle and tendon receptors (D) Periosteal nerves (E) Vascular nerves
The answer is D: Periosteal nerves. The periosteum contains a dense population of pain fi bers and is very sensitive to tearing, tension, or torsion. Thus, the severe pain associated with bone injury emanates mainly from trauma to the periosteum. Choice A (Nerves in compact bone) is incorrect. Bone tissue has relatively few sensory nerve endings, regardless of the type of bone. Thus, little (if any) pain would be derived from the fractured bone tissue. Choice B (Nerves in trabecular bone) is incorrect. Bone tissue has relatively few sensory nerve endings, regardless of the type of bone. Thus, little (if any) pain would be derived from the fractured bone tissue. Choice C (Surrounding muscle and tendon receptors) is incorrect. Pain from a bony fracture does not originate from surrounding muscle or tendon because the sensory receptors in those tissues are primarily proprioceptive (e.g., muscle spindles, Golgi tendon organs). However, if muscles and tendons are damaged as well, pain will emanate from these tissues as a secondary event. Choice E (Vascular nerves) is incorrect. Bones receive a rich vascular supply. However, the nerves that accompany the vessels are primarily vasomotor nerves that regulate blood fl
A teenage boy breaks a pane of glass with his fi st and receives a laceration to the posterior aspect of his wrist. He notices the tendons that cross his wrist lift out of place (or bowstring) when he extends his wrist. Which of the following structures was most likely cut by the broken glass? (A) Investing deep fascia (B) Intermuscular septum (C) Bursa (D) Retinaculum (E) Synovial tendon sheath
The answer is D: Retinaculum. A retinaculum is a thickened band of deep fascia that serves to hold tendons in place where they cross joints, as shown in the illustration. The presence of a retinaculum is important in muscle mechanics because it prevents tendons from lifting up out of place and bowstringing across the shortened joint angle created when the muscles crossing that joint contract. Because the tendons of the wrist lift out of place when the teenager extends his wrist, the retinaculum was damaged by the broken glass. Choice A (Investing deep fascia) is incorrect. The deep fascia is the relatively dense, organized connective tissue layer that lies deep to the skin and subcutaneous connective tissue (superfi cial fascia). Deep fascia is located in virtually all regions of the body, and deep extensions of this fascia may tightly enclose underlying structures (e.g., muscles, neurovascular bundles) to form investing deep fascia. Deep fascia may be specialized in certain places in order to serve specifi c functions (e.g., a retinaculum). Choice B (Intermuscular septum) is incorrect. An intermuscular septum is a deep, thickened extension of deep fascia that runs between muscles down to a central skeletal attachment. The organized arrangements of deep fascia, intermuscular septa, and skeleton, notably pronounced in the limbs, are termed osseo-fascial compartments. These compartments serve to group muscles with similar functions and generally similar innervation into larger working units. The compartment walls may add surface area for attachment of muscle fi bers and aid in creating musculovenous pumps to return blood to the heart. Choice C (Bursa) is incorrect. A bursa is a closed, collapsed sac with a serous membrane lining that contains a thin fi lm of synovial fl uid. Bursae serve to decrease friction and facilitate movement between structures that rub against one another (e.g., between skin and bony projections; between tendons and bones). Choice E (Synovial tendon sheath) is incorrect. A synovial tendon sheath is a specialized, elongate bursa that encloses a tendon. These sheaths are common where tendons cross joints (e.g., wrist and ankle) and serve to decrease friction between the tendons and the bony surfaces.
Which of the following is true of the anatomical position? (A) The humerus is proximal to the scapula. (B) The radius is medial to the ulna. (C) The vertebral arch is ventral to the vertebral body. (D) The femur is superior to the fi bula. (E) The phalanges of the foot are cranial to the metatarsals.
The answer is D: The femur is superior to the fi bula. In the anatomical position, a person is standing erect, facing anterior (forward), with the upper limbs by the sides, the palms facing anterior, the lower limbs placed together with the soles on the ground, and the toes pointing anterior. In this position, the thigh is superior to (above) the lower leg. Thus, the femur is superior to both the tibia and fi bula. Choice A (The humerus is proximal to the scapula) is incorrect. The humerus hangs from the lateral corner of the scapula; thus, it is lateral and inferior to the scapula. The humerus also may be described as distal to the scapula because it is further away from the attachment of the upper limb to the trunk. Choice B (The radius is medial to the ulna) is incorrect. The radius is the bone in the forearm located further away from the midline. Therefore, the radius is located lateral to the ulna. Choice C (The vertebral arch is ventral to the vertebral body) is incorrect. The vertebral arch, which is composed of the paired pedicles and laminae, is located dorsal (posterior; behind) to the body of the vertebra. Choice E (The phalanges of the foot are cranial to the metatarsals) is incorrect. The phalanges (toes) are positioned anterior to (or in front of) the metatarsals, which are located in the body of the foot. The phalanges also can be described as being distal to the metatarsals in that they are further away from the attachment/origin of the foot.
A 20-year-old college student on spring break suffers a fi rstdegree sunburn on her back and upper limbs. Which of the following integumentary structures/functions is most likely affected? (A) Hair follicles (B) Subcutaneous fat (C) Vitamin A production (D) Parasympathetic nerve endings (E) General sensory nerve endings
The answer is E: General sensory nerve endings. Burns are classifi ed in increasing order of severity, according to the depth of damage to the skin. First-degree burns are superfi cial depth injuries (e.g., most sunburns) that damage only the epidermis. Second-degree burns are partial-thickness injuries that affect the epidermis and superfi cial part of the dermis. Thirddegree burns are full-thickness injuries that damage the entire depth of the skin and may include deeper structures as well. General sensory (General Somatic Afferent; GSA) nerves are the general sensory nerves that register pain and other general
Which of the following structures are innervated by somatic motor neurons? (A) Meissner corpuscles (B) Arrector pili muscles of hair follicles (C) Myocardium of the left ventricle (D) Wall of the axillary artery (E) Semispinalis muscle
The answer is E: Semispinalis muscle. The system of identifying functional components of nerves is used to organize neuron types according to their anatomical distribution, functional properties, and developmental patterns. Five defi ned functional components exist, including general sensory, visceral sensory, visceral motor, somatic motor, and special sensory. Somatic motor (General Somatic Efferent; GSE) neurons are motor neurons that supply skeletal muscles derived from embryonic myotomes, such as the semispinalis muscle in the back. Choice A (Meissner corpuscles) is incorrect. Meissner corpuscles are widely distributed (generalized) sensory receptors that carry general sensory (General Somatic Afferent; GSA) fi bers from the body wall and limbs to the central nervous system. Choice B (Arrector pili muscles of hair
A young boy uses his right hand to screw-in a new light bulb. Which of the following terms best describes the screw-home movement of his forearm? (A) Flexion (B) Abduction (C) Pronation (D) Adduction (E) Supinatio
The answer is E: Supination. The screw-home movement is the clockwise motion that drives a screw into its receptacle, in this case the bulb into the socket. When using the right hand, the palm and forearm turn laterally and the palm moves from facing posterior to facing anterior, which is supination. Choice A (Flexion) is incorrect. Flexion is the action of decreasing the angle between parts while moving through the median or sagittal planes. Choice B (Abduction) is incorrect. Abduction refers to movements going away from the midline in the coronal plane. Choice C (Pronation) is incorrect. Pronation is the opposite of supination. When pronating the right hand, the palm and forearm turn medially so that the palm moves from facing anterior to facing posterior. In this case, right-handed pronation is a counter-clockwise movement that would unscrew the light bulb. However, when using the left hand, pronation produces the screw-home movement. Choice D (Adduction) is incorrect. Adduction refers to movements going toward the midline in the coronal plane.
A 55-year-old woman presents with ulceration and pain in the skin around and including her right nipple. Her physician correctly identifi es the affected area as that of the T4 dermatome. The pain this woman is suffering could be related to which of the following spinal segmental levels? (A) T3 only (B) T4 only (C) T3 and T4 (D) T4 and T5 (E) T3, T4, and T5
The answer is E: T3, T4, and T5. A dermatome is the area of skin innervated by sensory fi bers (i.e., by the dorsal root) from a single spinal segment. The classic anatomical dermatome map shown in the illustration indicates a barber-pole-like distribution of discrete bands of cutaneous territories. However, this standard map is somewhat deceiving in that there is actually considerable overlap between the dermatomes supplied by adjacent spinal cord segments. Thus, any one dermatome is actually supplied by three spinal segments: one major supplying segment plus two smaller supplying adjacent segments that overlap with the main segment. Choice A (T3 only) is incorrect. While this spinal segment contributes to the supply of the T4 dermatome (with T4 the major component), it does not account for the entire innervation. Choice B (T4 only) is incorrect. Damage to only the T4 dermatome would be hard to detect due to the overlap of innervation from the T3 and T5 spinal nerves. Choice C (T3 and T4) is incorrect. While this combination of damaged nerves more fully accounts for the supply of the T4 dermatome, it does not account for the entire supply due to the overlap of innervation from T5. Choice D (T4 and T5) is incorrect. While this combination of damaged nerves more fully accounts for the supply of the T4 dermatome, it does not account for the
If the body were sectioned along a ___ plane, it would be divided into ___ portions. (A) sagittal...anterior and posterior (B) sagittal...superior and inferior (C) coronal...superior and inferior (D) coronal...right and left (E) horizontal...superior and inferior
The answer is E: horizontal...superior and inferior. A horizontal plane lies perpendicular to both the median and coronal (frontal) planes. It divides the body into superior (upper) and inferior (lower) portions. Choice A (sagittal...anterior and posterior) is incorrect. A sagittal plane runs parallel to the median sagittal plane. It divides the body into right and left portions. Choice B (sagittal...superior and inferior) is incorrect. A sagittal plane runs parallel to the median sagittal plane. It divides the body into right and left portions. Choice C (coronal...superior and inferior) is incorrect. A coronal (or frontal) plane runs perpendicular to the median plane. It divides the body into anterior (front) and posterior (back) portions. Choice D (coronal...right and left) is incorrect. A coronal (or frontal) plane runs perpendicular to the median plane. It divides the body into anterior (front) and posterior (back) portions.