Anatomy 1

file:///C|/Users/drcon_000/Desktop/Textbooks%20PDF/Q%20bank/Anat%201/100_files/item.htm[2015-03-25 6:12:32 PM]

A wound to the posterior left axillary line, between the ninth and tenth rib, and extending approximately 5cm deep, will most likely damage which organ?

A. Ascending colonB. DuodenumC. Left kidneyD. Left lobe of the liverE. Spleen

The correct answer is E. The spleen follows the long axes of ribs 9 to 11 and lies mostly posterior tothe stomach, above the colon, and partly anterior to the kidney. It is attached to the stomach by a broadmesenterial band, the gastrosplemic ligament. Therefore, it is the most likely organ of the group to bepierced by a sharp object penetrating just above rib 10 at the posterior axillary line. Note that the pleuralcavity, and possibly the lower part of the inferior lobe of the lung, would be pierced before the spleen.

The ascending colon (choice A) is on the wrong side (the right) to be penetrated by a sharp instrumentpiercing the left side.

Most of the duodenum (choice B) is positioned too far to the right to be affected by this injury. Even thethird part of the duodenum, which runs from right to left, would still be out of harm's way. In addition, theduodenum lies at about levels L1 to L3, placing it too low to be injured in this case.

The superior pole of the left kidney (choice C) is bordered by the lower part of the spleen. However, it iscrossed by rib 12 and usually does not extend above rib 11. It would probably be too low and medial tobe injured in this case because this penetration is at the posterior axillary line.

The left lobe of the liver (choice D) is positioned just beneath the diaphragm, just over and anterior tothe stomach. The anterior positioning of this structure makes it an unlikely candidate for injury in thiscase. Even with deep penetration at the correct angle, it would not be penetrated before the spleen.


A patient's left hypoglossal nerve (CN XII) is injured during a carotid endarterectomy. Which of thefollowing would most likely result from this injury?

A. Decreased gag reflex on the leftB. Decreased salivation from the left submandibular and sublingual salivary glandsC. Deviation of the tongue to the left on protrusionD. Inability to elevate the pharynx on the left during swallowing

E. Inability to perceive sweet and salt taste sensation on the anterior part of the left side of thetongue

The correct answer is C. The hypoglossal nerve is a pure motor nerve (general somatic efferent) to theintrinsic and most extrinsic muscles of the tongue. If the nerve is damaged, denervation atrophy of theaffected side will permit the intact musculature of the opposite side to operate unopposed, therebyprotruding the tongue to the side of the injury.

The gag reflex (choice A) is mediated by the glossopharyngeal nerve (CN IX; afferent limb) and thevagus nerve (CN X; efferent limb).

Choice B is incorrect because the preganglionic parasympathetic fibers that regulate these two salivaryglands are carried by the chorda tympani (which joins with the lingual nerve) to the submandibularganglion. Postganglionic fibers are then distributed to these glands.

The muscles responsible for elevation of the pharynx (choice D) are innervated primarily by the vagusnerve (CN X).

Choice E is incorrect because the taste fibers for the anterior two thirds of the tongue are carried via thechorda tympani to the facial nerve (CN VII) and hence to the brainstem.


A patient with paresthesia of the medial side of the hand and forearm undergoes surgery to correct it. Ifthe anterior scalene muscle is cut during this surgery, what nearby nerve must be avoided?

A. Phrenic nerveB. Recurrent laryngeal nerveC. Superior laryngeal nerveD. Suprascapular nerveE. Vagus nerve

The correct answer is A. The patient is suffering from scalene triangle syndrome (thoracic outletsyndrome). The lower trunk of the brachial plexus and the subclavian artery are being compressedbetween the anterior scalene muscle and the middle scalene muscle. Incision of the anterior scalenemuscle will relieve this compression. The phrenic nerve lies on the anterior surface of the anterior scalenemuscle deep to the prevertebral fascia. If this nerve is cut, the diaphragm on that side of the body will beparalyzed. Anatomically, the phrenic nerve is one of the nerves of the cervical plexus. This nervedistributes to the diaphragm other nerves of the cervical plexusm including the ansa cervicalis, lesserocciptital, transverse cervical, supraclavical, and greater auricular nerves, as well as the cervical nerves.

The recurrent laryngeal nerve (choice B) is a branch of the vagus nerve. On the left side it recurs aroundthe aortic arch, and on the right side it recurs around the right subclavian artery. It ascends to the larynxin the tracheoesophageal groove. The nerve innervates several laryngeal muscles and the laryngealmucosa inferior to the vocal folds. It is not in contact with the anterior scalene muscle.

The superior laryngeal nerve (choice C) is a branch of the vagus nerve that arises just after the vagusnerve passes through the jugular foramen. It innervates the cricothyroid muscle of the larynx and thelaryngeal mucosa above the vocal folds. The superior laryngeal nerve is not in contact with the anteriorscalene muscle.

The suprascapular nerve (choice D) is a branch of the upper trunk of the brachial plexus. It arises fromthe upper trunk after the upper trunk has passed between the anterior and middle scalene muscles. Thesuprascapular nerve innervates the supraspinatus and infraspinatus muscles.

The vagus nerve (choice E) lies within the carotid sheath within the neck. The carotid sheath is anteriorto the prevertebral fascia. The vagus nerve is not in contact with the anterior scalene muscle.


Compression of a cranial nerve by a large aneurysm of the right superior cerebellar artery immediatelydistal to its origin from the basilar artery would cause which of the following clinical findings?

A. Loss of abduction of the right eyeB. Loss of adduction of the right eyeC. Loss of depression of the right eye from the adducted positionD. Loss of sensation on the right side of the faceE. Loss of visual field of the right eye

The correct answer is B. The oculomotor nerve emerges from the interpeduncular fossa of the midbrainand then passes between the superior cerebellar artery and the posterior cerebral artery immediatelylateral to the basilar artery. Aneurysm of any of these three arteries may compress the nerve. Theoculomotor nerve innervates a number of extraocular muscles in the orbit, including the medial rectusmuscle, which is responsible for adduction of the eye.

Abduction of the eye (choice A) is accomplished by the lateral rectus muscle. This muscle is innervatedby the abducens nerve, which arises more caudally from the brainstem and is not in contact with thisartery.

Depression of the eye from the adducted position (choice C) is accomplished by the superior obliquemuscle. This muscle is innervated by the trochlear nerve, which emerges from the dorsal surface of themidbrain and passes lateral to the cerebral peduncle before entering the cavernous sinus. A superiorcerebellar artery aneurysm would not compress this nerve.

Sensation on the face (choice D) is mediated by the trigeminal nerve. This nerve arises from theanterolateral surface of the pons and is not in contact with this artery.

Loss of visual field (choice E) results from lesions of the optic nerve or other elements of the visualpathway. These are not in contact with this artery.


The two most important hormones controlling Calcium metabolism are secreted from the:

A. Parathyroid and thyroid glandsB. Thyroid and thymus glandsC. Adenohypophysis and parathyroid glandsD. Adrenal cortex and thyroid glandsE. Parathyroid and adrenal glands

The correct answer is A.PTH, or parathyroid hormone, is considered to be the most important hormonecontrolling calcium metabolism. It increases serum calcium by increasing bone mineral resorption byosteoclasts, increasing digestive absorption of calcium, and decreasing calcium excretion by the kidney.PTH is secreted by principal cells of the parathyroid. The antagonist hormone, calcitonin, is secreted byparafollicular cells of the thyroid (follicular cells secrete thyroxin). It reduces serum calcium by promotingcalcium depositon in bones, decreasing digestive absorption of calcium, and promoting calcium excretion.Note that the term adenohypophysis in answer choice C refers to the anterior pituitary. This term andneurohypophysis (posterior pituitary) are often used on NBDE.


During a cranial nerve test, the patient cannot elevate her right eye from the abducted position. Which ofthe following muscles is paralyzed?

A. Right inferior obliqueB. Right inferior rectusC. Right lateral rectusD. Right superior obliqueE. Right superior rectus

The correct answer is E. The superior rectus muscle can elevate and adduct the eye from the neutralposition. From the abducted position, it is the only muscle that can elevate the eye.

The inferior oblique muscle (choice A) can elevate and abduct the eye from the neutral position. Fromthe adducted position, it is the only muscle that can elevate the eye.

The inferior rectus muscle (choice B) can depress and adduct the eye from the neutral position. From theabducted position, it is the only muscle that can depress the eye.

The lateral rectus muscle (choice C) can abduct the eye.

The superior oblique muscle (choice D) can depress and abduct the eye from the neutral position. Fromthe adducted position, it is the only muscle that can depress the eye.


Several arterial branches penetrate into the distal end of the lesser curvature of the stomach. Which of thefollowing arteries usually supplies these branches?

A. Left gastricB. Left gastroepiploicC. Right gastricD. Right gastroepiploicE. Short gastric

The correct answer is C. The arterial supply of the stomach is complex; it therefore has a goodpotential to appear on the NBDE. The right gastric artery supplies the distal lesser curvature.

The left gastric artery (choice A) supplies the proximal lesser curvature.

The left gastroepiploic artery (choice B) supplies the proximal greater curvature below the splenic artery.

The right gastroepiploic artery (choice D) supplies the distal greater curvature.

The short gastric artery (choice E) supplies the proximal greater curvature above the splenic artery.


Contraction of which of the following muscles contributes most to the backward movement of the lowerjaw during the process of mastication?

A. DigastricB. Lateral pterygoidC. Medial pterygoidD. MylohyoidE. Temporalis

The correct answer is E. Mastication is a complex process involving alternating elevation, depression,forward movement, and backward movement of the lower jaw. The backward-movement step isaccomplished by the posterior fibers of the temporalis muscle. The temporalis originates along thetemporal lines of the temporal bone and inserts into the coronoid process of the mandible. It is innervatedby the manibular branch of the trigeminal nerve.

The digastric (choice A) helps to depress (open) the lower jaw during chewing.

The lateral pterygoid (choice B) helps to move the lower jaw forward, laterally, or downward duringchewing.

The medial pterygoid (choice C) helps to elevate (close) the lower jaw during chewing.

The mylohyoid (choice D) helps to depress (open) the lower jaw during chewing.


Most fascia of the body that attach to bones attach by which of the following mechanisms?

A. Blending with the covering periosteumB. Inserting deeply into the cancellous boneC. Inserting deeply into the cartilageD. Inserting deeply into the diaphysisE. Inserting deeply into the marrow

The correct answer is A. Fascial straps (retinacula) and fascial coverings of muscles or muscle groupscharacteristically attach to nearby bones by blending with the covering periosteum. No deep attachmentsare usually made by fascia.

Cancellous bone (choice B) is spongy bone, which is usually found in marrow and is not the site forfascial attachment.

Fascia do not usually attach to cartilage (choice C).

Fascia attaches to bony shafts, or diaphyses (choice D), superficially via the periosteum.

Fascia do not penetrate the bone to reach the marrow (choice E).


A newborn baby is noted to have a left unilateral cleft lip. There are no abnormalities of the baby's palate.Which of the following developmental defects accounts for this occurrence?

A. Failure of the left lateral palatine process to fuse with the median palatine processB. Failure of the left maxillary prominence to unite with the left medial nasal prominenceC. Failure of the primary palate to fuse with the secondary palateD. Failure of the right and left medial nasal prominences to mergeE. Failure of the right palatine process to fuse with the left palatine process

The correct answer is B. In the formation of the upper lip, the right and left medial nasal prominencesmerge to form the philtrum of the upper lip. The lateral maxillary prominence then merges with themerged medial nasal prominences. Failure of this merger to occur results in a unilateral cleft lip.

Failure of a lateral palatine process to fuse with the median palatine process (choice A), which issynonymous with a failure of the primary palate to fuse with the secondary palate (choice C), results in aprimary cleft palate. Primary clefts of the palate are found anterior to the incisive foramen of the palate.Primary cleft palates may occur along with cleft lips but are the result of a separate developmental defect.

Failure of the right and left medial nasal prominences to merge (choice D) results in a median cleft lip.This is a rare anomaly. Normally, the right and left medial nasal prominences merge into a singleprominence that forms the philtrum of the lip.

Failure of the right and left palatine processes to fuse (choice E) results in a secondary cleft palate.Secondary cleft palates are found posterior to the incisive foramen. Normally, the right and left palatineprocesses fuse together and fuse to the primary palate.


A patient experiences visual difficulties. When a light is shined in her right eye, there is no pupillaryresponse in either eye. However, upon shining a light in her left eye, both ipsilateral and contralateralpupillary responses are apparent. Her extraocular movements are intact. What is the most likely location ofher lesion?

A. Oculomotor nerve, left sideB. Oculomotor nerve, right sideC. Optic nerve, left sideD. Optic nerve, right sideE. Trochlear nerve, left side

The correct answer is D. Know your cranial nerves! This woman has a "Marcus-Gunn pupil" with adefect in the afferent pathway of the optic nerve (in this case, on the right side). Recall that the afferentlimb of the pupillary light reflex is the optic nerve (CN II); the efferent limb is the oculomotor nerve (CNIII; parasympathetic fibers). When light is shined into her right eye, because her right optic nerve is notfunctioning properly, the light signal is not transmitted to the central nervous system (CNS), resulting in nopupillary response. As light is shined into her left eye, the left optic nerve transmits the signal to the CNS,which then sends an outbound signal through both the right and left oculomotor nerves to cause pupillaryconstriction in both eyes. Anatomically, the optic nerve is a special sensory nerve that originates in theretina of the eye, passes through the optic foramen of the sphenoid bone, and has a destination in thediencephalon via the optic chiasm.

The oculomotor nerve (choices A and B) innervates all extraocular muscles except the lateral rectus(innervated by the abducens nerve) and the superior oblique (innervated by the trochlear nerve choiceE). The oculomotor nerve also mediates pupillary constriction (parasympathetic fibers), eyelid opening(levator palpebrae), and innervates the ciliary muscle (allowing accommodation).

A patient with a lesion of the left optic nerve (choice C) would have no pupillary responses in either eyewhen shining a light in the left eye; pupillary responses would be present in both eyes when shining alight in the right eye.


At which of the following ages does fetal movement first occur?

A. 1 monthB. 2 monthsC. 4 monthsD. 6 monthsE. 7 months

The correct answer is B. Neuromuscular development is sufficient to allow fetal movement in the eighthweek of life. Other features of Week 8 include the first appearance of a thin skin, a head as large as therest of the body, forward-looking eyes, appearance of digits on the hands and feet, appearance of testesand ovaries (but not distinguishable external genitalia), and a crown-rump length of approximately 30mm. By the end of the eighth week, nearly all adult structures have at least begun to develop, and thefetus "looks like a baby."


If the tongue deviates to the right side when protruded, the most likely cause is paralysis of which of thefollowing muscles?

A. Left genioglossusB. Left hyoglossusC. Left palatoglossusD. Right genioglossusE. Right hyoglossus

The correct answer is D. The genioglossus muscle is innervated by the hypoglossal nerve. The functionof the genioglossus muscle is to pull the tongue forward (protrude) and toward the opposite side. Whenthe right genioglossus muscle is paralyzed, the left genioglossus muscle pulls the tongue forward and tothe right.

If the left genioglossus muscle were paralyzed (choice A), the tongue would deviate toward the left onprotrusion because of the unopposed action of the right genioglossus muscle. The left genioglossus muscleis innervated by the left hypoglossal nerve.

The hyoglossus muscles (choices B and E) are innervated by the hypoglossal nerves. The function ofthese muscles is to retract the tongue. These muscles are not active during protrusion of the tongue.

The palatoglossus muscle (choice C) are innervated by the vagus nerves rather than the hypoglossalnerves. Their function is to pull the tongue back (retract) and upward toward the palate.


Which of the following is a derivative of the second pharyngeal arch?

A. Eustachian tubeB. External auditory meatusC. Palatine tonsilD. Stylohyoid muscleE. Tensor tympani

The correct answer is D. The stylohyoid is derived from the second pharyngeal arch, which also givesrise to the muscles of facial expression, the stapedius, the posterior belly of the digastric muscle,Reichert's cartilage, and the facial nerve.

The Eustachian tubes (choice A) are derived from the first pharyngeal pouch, which also gives rise to themiddle ear cavity and the inner epithelial lining of the tympanic membrane.

The external auditory meatus (choice B is derived from the first pharyngeal cleft, which also gives rise tothe outer epithelial lining of the tympanic membrane.

The palatine tonsil (choice C) is derived from the epithelial lining of the second pharyngeal pouch.

The tensor tympani (choice E) is derived from the first pharyngeal arch, which also gives rise to themuscles of mastication, the anterior belly of the digastric muscle, the mylohyoideus, the tensor velipalantini, the maxillary and mandibular bones, and the maxillary and mandibular divisions of the trigeminalnerve.

Note that knowing the embryology of these structures helps you remember the innervation of the musclesof the face.

First pharyngeal arch muscles of mastication trigeminal nerve

Second pharyngeal arch muscles of facial expression facial nerve


Damage to the parasagittal region and falx cerebri will most likely result in which of the followingneurologic deficits?

A. Altered tasteB. Leg paralysisC. Loss of facial sensationD. PtosisE. Unilateral deafness

The correct answer is B. A meningioma of the parasagittal region and the falx cerebri would be locatedat the top of the brain, near the midline. In this position, it could compress the sensory or motor cortexsupplying the lower extremities. The falx cerebri is a fold of dura mater that projects between the cerebralhemispheres in the longitudinal tissues. Its interior portions attach anteriorly to the crista galli andposteriorly to the internal occipital crest.

Taste (choice A) is supplied by cranial nerves VII, IX, and X. These nerves arise from the brainstem.

Facial sensation (choice C) is supplied by cranial nerve V, the nuclei of which are in the brainstem.Furthermore, the area of the sensory cortex that subserves the face is on the lateral aspect of the cortexand would not be affected by a tumor in the parasagittal region.

Ptosis (choice D) can be caused by a deficit in cranial nerve III, which arises from the brainstem.

Unilateral deafness (choice E) suggests damage to cranial nerve VIII, which arises from the brainstem.


In which of the following structures are the opacifications located with cataract formation?

A. Aqueous humorB. CorneaC. LensD. Optic nerveE. Retina

The correct answer is C. Cataracts are lens opacifications. It is not known whether senile cataractsrepresent disease or normal opacification with age. Cataracts may occur as a consequence of diabetesmellitus, long-term steroids, or congenital infections. They are successfully treated at present with lensextraction and implantation of prosthetic lenses. The diagnostic characteristics for cataracts are as follows:1) blurred vision that is progressive over months to years, 2) no pain or redness is seen, and 3) lensopacities may be invisible or grossly visible.

Aqueous humor (choice A) is continually replaced due to active secretion by the ciliary body. As such, itdoes not undergo opacification; it is in constant flux.

Corneal opacification (choice B) is generally a consequence of squamous metaplasia, in which thetransparent, nonkeratinized, squamous cells are replaced by opaque, keratinized, squamous cells.Squamous metaplasia is a reparative process, usually due to friction injury to the cornea or a vitamin Adeficiency.

The optic nerve (choice D) is not transparent, and it does not undergo opacification injury. It may,however, atrophy due to ischemic, traumatic, infective, or metabolic insults.

The retina (choice E) consists of multiple layers of neural cells. The retina is transparent but is not thesite of cataract formation.


A sharp instrument passing through the superior orbital fissure would most likely sever which of thefollowing structures?

A. Abducens nerveB. Facial nerveC. Mandibular nerveD. Maxillary nerveE. Middle meningeal artery

The correct answer is A. A good way to remember what passes through the superior oribital fissure isthat everything that innervates the eye, other than the optic nerve, passes through this fissure. Thisincudes the oculomotor nerve(CN III), the trochlear nerve (CN IV), the ophthalmic nerve (V1), and theabducens nerve (CN VI).

The facial nerve (CN VII; choice B) passes through the internal auditory meatus.

The mandibular nerve (V3; choice C) passes through the foramen ovale.

The maxillary nerve (V2; choice D) passes through the foramen rotundum.

The middle meningeal artery (choice E) passes through the foramen spinosum.


A knife wound to the neck damages the posterior cord of the brachial plexus. Which of the followingmuscles would be most likely be paralyzed?

A. DeltoidB. Flexor carpi ulnarisC. Flexor digitorum superficialisD. Flexor pollicis brevisE. Palmaris longus

The correct answer is A. The posterior cord supplies the axillary and radial nerves. Of the muscleslisted, only the deltoid is supplied by one of these two nerves, specifically the axillary nerve. The deltoidoriginates from the clavicle and scapula. It inserts into the deltoid tuberosity of the humerus. This muscleis responsible for abduction of the arm.

The flexor carpi ulnaris (choice B) is supplied by the ulnar nerve.

The flexor digitorum superficialis (choice C), the flexor pollicis brevis (choice D), and the palmarislongus (choice E) are supplied by the median nerve.


During the process of meiosis, a single homologous chromosome pair fails to separate during the firstmeiotic division. This failure would be most likely to produce which of the following conditions iffertilization occurs and an embryo later develops?

A. Balanced translocationB. TriploidyC. TrisomyD. Unbalanced translocationE. Uniploidy

The correct answer is C. Meiosis is cell division that produces gametes with half of the normal somaticchromosome complement. The process described is nondisjunction, which will cause one daughter cell tohave 24 chromosomes, while the other will have 22 chromosomes. When a gamete with the normal 23chromosomes combines at fertilization with a gamete with 22 or 24 chromosomes, the embryo will have47 chromosomes (trisomy) or 45 chromosomes (monosomy). Nondisjunction can occur in either the firstor second meiotic division.

Balanced translocation (choice A) occurs when non-homologous chromosomes exchange genetic materialin such a way that no critical genetic material is lost.

Triploidy (choice B) is the term used when a cell has 69 chromosomes (3N or 3 sets), and can occur intumors or when an egg is fertilized by two sperm.

An unbalanced translocation (choice D) occurs when non-homologous chromosomes exchange geneticmaterial with a net loss or gain of critical genetic material.

Uniploidy (choice E) is the state of having 23 chromosomes, seen normally in sperm and eggs.


The superior ophthalmic vein directly communicates with which of the following dural venous sinuses?

A. Cavernous sinusB. Occipital sinusC. Sigmoid sinusD. Superior petrosal sinusE. Straight sinus

The correct answer is A. The anterior continuation of the cavernous sinus, the superior ophthalmic vein,passes through the superior orbital fissure to enter the orbit. Veins of the face communicate with thesuperior ophthalmic vein. Because of the absence of valves in emissary veins, venous flow may occur ineither direction. Cutaneous infections may be carried into the cavernous sinus and result in a cavernoussinus infection, which may lead to an infected cavernous sinus thrombosis. The cavernous sinus is lateralto the pituitary gland and contains portions of cranial nerves III, IV, V1, V2, and VI, and the internalcarotid artery.

The occipital sinus (choice B) is at the base of the falx cerebelli in the posterior cranial fossa. It drainsinto the confluence of sinuses.

The sigmoid sinus (choice C) is the anterior continuation of the transverse sinus in the middle cranialfossa. The sigmoid sinus passes through the jugular foramen and drains into the internal jugular vein.

The superior petrosal sinus (choice D) is at the apex of the petrous portion of the temporal bone and is aposterior continuation of the cavernous sinus. The superior petrosal sinus connects the cavernous sinuswith the sigmoid sinus.

The straight sinus (choice E) is at the intersection of the falx cerebri and the falx cerebelli in theposterior cranial fossa. The straight sinus connects the inferior sagittal sinus with the confluence ofsinuses.


In preparation for a procedure to remove the fingernail on an index finger, the physician would most likelyanesthetize a branch of the

A. anterior interosseus nerveB. median nerveC. musculocutaneous nerveD. radial nerveE. ulnar nerve

The correct answer is B. The median nerve supplies the surface of the lateral palm, the palmar surfaceof the first three digits, and the distal dorsal surface of the index and middle fingers (including the nailbeds). Therefore, prior to performing surgery in this area, it is essential to anesthetize a branch of thisnerve (possibly a proper digital branch) to eliminate pain sensation around the nail bed of the indexfinger. The median nerve of the branchial plexus distributes to the flexor muscles on the forearm (flexorcarpi radialis and palmaris longus), the pronators (p. quadratus and p. teres), digital flexors, and skin overthe lateral surface of the hand.

Neither the anterior interosseus (choice A) nor the musculocutaneous (choice C) nerves supplies thehand. The anterior interosseous nerve supplies the flexor pollicis longus, the lateral half of flexor digitorumprofundus, and pronator quadratus. The musculocutaneous nerve supplies the coracobrachialis, biceps,and most of the brachialis muscle, then becomes the lateral cutaneous nerve of the forearm.

The radial nerve (choice D) supplies skin on the radial side of the dorsal surface of the hand, but not thefingertips.

The ulnar nerve (choice E) supplies the palmar and dorsal surfaces of the medial hand, including thepalmar and dorsal surfaces of the fourth and fifth digits.


Which glandular area secretes hormones which are products of tyrosine metabolism?

A. Alpha cells of pancreasB. Beta cells of pancreasC. Adrenal cortexD. Adrenal medullaE. Testes

The correct answer is D.The products of the adrenal medulla are epinephrine (adrenalin) andnorepinephrine (noradrenalin). The pathway of production of these compunds is a s follows: tyrosine toDOPA to dopamine to norepinephrine to epinephrine. The hormone secreted by alpha cells of thepancreas is glucagon, while beta cells secrete insulin. Both are peptide hormones. The adrenal cortexsecretes a variety of hormones including cortisol and aldosterone, both steroid hormones. The testessecrete testosterone, also a steroid hormone.


Most of the oocytes in the ovary of a prepubescent girl are in which meiotic stage?

A. Anaphase of the second meiotic divisionB. Metaphase of the first meiotic divisionC. Metaphase of the second meiotic divisionD. Prophase of the first meiotic divisionE. Telophase of the first meiotic division

The correct answer is D. The first meiotic division is the "reduction" meiotic division, in which thediploid complement of DNA is reduced to a haploid complement. The bulk of oocytes in premenopausalwomen, girls, and babies are arrested at prophase of the first meiotic division. Postmenopausal womenhave very few viable oocytes. It is important to note that ovulation occurs before the oocyte is completelymature. The secondary oocyte leaving the follicle is in metaphase of the second meiotic division (choiceC). The cell's metabolic operations have been discontinued and the oocyte drifts in a state of "suspendedanimation," awaiting the necessary stimulus for further development. If fertilization does not occur, theoocyte disintegrates without completing meiosis.


A newborn infant has some of its abdominal viscera protruding through a defect in the abdominal wall.Which of the following is the likely cause of this defect?

A. Failure of the intestinal loop to retract from the umbilical cordB. Failure of the yolk stalk to degenerateC. Failure of peritoneal fusionD. Incomplete fusion of the lateral body foldsE. Umbilical herniation

The correct answer is D. During the fourth week of development, the lateral body folds move ventrallyand fuse in the midline to form the anterior body wall. Incomplete fusion results in a defect that allowsabdominal viscera to protrude from the abdominal cavity, a condition known as gastroschisis.

During development, the midgut normally herniates into the umbilical cord and then subsequently retractsinto the abdominal cavity. Failure of the intestinal loop to retract from the umbilical cord (choice A)results in omphalocele.

Failure of the yolk stalk to degenerate (choice B) results in an ileal (Meckel's) diverticulum or a vitellinefistula or cyst. In the early embryo, the gut tube is connected to the yolk sac by a narrow connectionknown as the yolk stalk. Normally, this connection degenerates.

During development, certain peritoneal organs fuse with the posterior abdominal wall to becomesecondarily retroperitoneal. Failure of this peritoneal fusion (choice C) will result in certain organs thatare normally immobile being mobile (e.g., mobile cecum).

Umbilical herniation (choice E) results from abdominal viscera protruding through a weakness in theabdominal wall after development. Such protrusions are covered by subcutaneous fascia and skin,distinguishing them from gastroschisis.


If a patient has a drooping right eyelid and a dilated right pupil, which of the following neural structures ismost likely affected?

A. Cervical sympathetic chainB. Facial nerveC. Oculomotor nerveD. Superior cervical ganglionE. Trigeminal nerve

The correct answer is C. The oculomotor nerve innervates the levator palpebrae superioris, whichelevates the eyelid. This nerve also innervates the inferior oblique muscles, as well as the superior,inferior, and medial rectus muscles. The oculomotor nerve also contains preganglionic parasympatheticfibers that synapse, in the ciliary ganglion, on postganglionic parasympathetic nerve fibers that innervatethe sphincter pupillae muscle, which constricts the pupil. A lesion of the oculomotor nerve may thereforeresult in both drooping of the eyelid (ptosis) and dilation of the pupil (mydriasis).

The cervical sympathetic chain (choice A) contains preganglionic sympathetic nerve fibers, arising fromthe upper thoracic spinal cord, which ascend to the cervical sympathetic ganglia. A lesion of these nervesmay result in Horner's syndrome, which includes a ptosis and miosis (pupillary constriction) and, often,anhidrosis (lack of sweating).

The facial nerve (choice B) innervates the muscles of facial expression, including the orbicularis oculimuscle. A lesion of this nerve may therefore result in the inability to close the eye.

The superior cervical ganglion (choice D) contains the cell bodies of postganglionic sympathetic nervesthat innervate structures in the head. A lesion of this structure will cause Horner's syndrome.

The trigeminal nerve (choice E) provides sensory innervation to much of the head. A lesion of this nervemay interfere with the corneal blink reflex.


An injection to anesthetize pain from a fracture of the seventh rib should be gien in what area?

A. Seventh intercostal space immediately below the seventh rib in the midclavicular lineB. Seventh intercostal space immediately below the seventh rib just lateral to the angle of the ribC. Seventh intercostal space immediately below the seventh rib just medial to the angle of the ribD. Sixth intercostal space immediately above the seventh rib in the midclavicular lineE. Sixth intercostal space immediately above the seventh rib just lateral to the angle of the rib

The correct answer is B. The seventh intercostal nerve (the anterior ramus of the seventh thoracicspinal nerve) innervates the seventh rib. After passing through the intervertebral foramen between theseventh and eighth thoracic vertebrae, the nerve lies in the seventh intercostal space. After passing theangle of the rib, it occupies a position along the lower border of the rib, in the costal groove. Use of alocal anesthetic at this point will anesthetize the rib.

By the time the intercostal nerve has reached the midclavicular line (choice A), it has already innervatedmost of the rib. Use of an anesthetic at this point would not be effective.

While the intercostal nerve is in the intercostal space medial to the angle of the rib (choice C), it is notalong the lower border of the rib.

The intercostal nerve does not lie along the upper border of the rib (choices D and E). Thus, injection atthese sites would not be effective.


The nucleus that lies immediately medial (and deep) to the uncus is the

A. amygdalaB. caudate nucleusC. claustrumD. hippocampusE. putamen

The correct answer is A. The uncus, which is the medial protrusion of the parahippocampal gyrus, is anexternal structure seen on the ventral surface of the temporal lobe. The amygdala is a collection of nucleithat lies directly beneath the uncus.

The caudate nucleus (choice B) is a deep nuclear structure that lies lateral to the lateral ventricles.

The claustrum (choice C) is a thin and elongated nucleus that lies just medial to the insular cortex.

The hippocampus (choice D) is a nuclear structure that lies in the interior of the parahippocampal gyrus.

The putamen (choice E) is a nuclear structure that resides lateral to the caudate and medial to theclaustrum.


A nursing home patient who aspirates while lying on his back would be most likely to develop pneumoniainvolving which of the following sites?

A. Anterior segment of the right upper lobeB. Apical segment of the right lower lobeC. Inferior lingular segment of the left upper lobeD. Lateral segment of the right middle lobeE. Superior lingular segment of the left upper lobe

The correct answer is B. Aspiration pneumonia is a common complication observed in nursing homepatients. The most probable site of the pneumonia can be anticipated by knowing the anatomy of thebronchial tree because the aspirated fluid usually flows downhill. In a supine or nearly supine patient, thefluid flows into the trachea and then into either of the (typically the right) main bronchi. The firstposteriorly located branch is the one leading to the apical aspect of (either) lower lobe. The lateral andposterior segments of the lower lobes are also supplied by posteriorly branching segmental bronchi. Incontrast, the posterior aspects of the upper lobes are somewhat protected by an initial anteriorly directedbifurcation before their segmental bronchi arise. All other segments of the bronchial tree and theircorresponding portions of lung are more anterior.


The hormone most responsible for regulating sodium balance is secreted from:

A. Zona glomerulosa of the adrenal cortexB. Zona reticularis of the adrenal medullaC. Zona fasiculata of the adrenal medullaD. Zona fasiculata of the adrenal cortexE. Zona glomerulosa of the adrenal medulla

The correct answer is choice A.Firstly, the hormone involved is aldosterone, which acts to increasesodium resorption in the kidney. Note that aldosterone (a mineralcorticoid) and the glucocorticoids(cortisol, cortisone) are produced by the adrenal cortex, not medulla. The medulla, with a differentdevelopmental origin and cell type, produces catecholamines such as epinephrine and norepinephrine. Thecortex, which is outside the medulla, is in three regions. On the outside is the Zona Glomerulosa, sourceof the mineralcorticoids. Inside of that is the Zona Fasiculata, which together with the innermost layer ofthe cortex, the Zona Reticularis, produce glucocortoids. Remember that interior to the Zona Reticularis,you will find the adrenal medulla. Also note that as a memory aid, the cortex layers from the outside inare G-F-R, like the GFR of the kidney.


During embryological development, hematopoiesis occurs in different organs at different times. Which ofthe following are the correct organs, in the correct sequence, at which hematopoiesis occursembryologically?

A. Amnion, yolk sac, placenta, bone marrowB. Placenta, liver and spleen, yolk sac, bone marrowC. Placenta, spleen and lymphatic organs, bone marrowD. Yolk sac, bone marrow, liver and spleenE. Yolk sac, liver, spleen and lymphatic organs, bone marrow

The correct answer is E. By the third week of development, hematopoiesis begins in the blood islandsof the yolk sac. Beginning at 1 month of age and continuing until 7 months of age, blood elements arealso formed in the liver. Hematopoiesis occurs in the spleen and lymphatic organs between 2 and 4months, and in the bone marrow after 4 months.


A woman suffers a fracture of the left tenth and eleventh ribs. Which of the following organs is most likelyto have been injured by these fractured ribs?

A. Descending colonB. JejunumC. Left adrenal glandD. Left kidneyE. Spleen

The correct answer is E. The spleen is a soft, friable organ with a thin capsule and is subject to injuryupon trauma to the left side of the abdomen. It is located in the upper left quadrant of the abdomen,deep to the left ninth, tenth, and eleventh ribs. It is the most commonly injured organ in the abdomen.The adult spleen contains the largest number of lymphoid tissues in the human body.

The descending colon (choice A) lies in a retroperitoneal position on the left side of the posteriorabdominal wall. The descending colon begins at the splenic flexure immediately inferior to the spleen.

The jejunum (choice B) is a peritoneal structure suspended by a long mesentery. It is located primarily inthe upper left quadrant of the abdomen. Its long mesentery allows the jejunum to be highly mobile andthus is not likely to be injured by trauma to the body wall.

The left adrenal gland (choice C) is a retroperitoneal structure that lies near the upper pole of the leftkidney. It is embedded within fat and is thus well protected from injury.

The left kidney (choice D) is a retroperitoneal structure that is well protected by fat.


The tongue will move in which direction when protuded with surgical damage to the right hypoglossalnerve?

A. DownwardB. UpwardC. Directly forwardD. To the rightE. To the left

The correct answer is D. There are two ways to answer this question. The formula method is that atongue with muscle or nerve injury will protrude toward the side of injury, in this case the right side. Thisis similar to the case of the mandible protruding toward the side of injury when a lateral pterygoid isinjured.The logical method is to imagine intrinsic muscles and extrinsic protruders of the tongue on theright side not receiving stimulation from innervation. In this case, only the left side protruders will operate.The tongue will protrude only on the left side, with the immobile right side acting as a stationary pivotwhile the tongue moves from left to right (toward the injured side).


You are asked to hold your upper arm against your lateral chest wall, with the palm upward. You thenrotate the hand so that the palm faces downward, without bending the wrist. This motion is known as:

A. abduction of the forearmB. adduction of the forearmC. flexion of the forearmD. pronation of the forearmE. supination of the forearm

The correct answer is D. When the forearm is rotated from anatomic position (palms facing forward,thumbs out) so that the palm faces posteriorly, the forearm is said to be pronated.

Abduction (choice A) raises the arm to a horizontal position away from the body; adduction (choice B)is the reverse.

Flexion (choice C) brings the arm or forearm forward, in front of the plane of the body.

Rotation of the forearm so that the palm faces forward (i.e., into anatomic position) is referred to assupination (choice E).


An abrasion results in the total loss of epidermis over a large area of an arm, but one month later, theabrasion has healed, with regrowth of the epidermis. Which of the following mechanisms accounts for therestoration of the epidermis over the abraded area?

A. Growth of epidermis from hair follicles and sweat glands in the dermisB. Migration of endothelial cells from newly grown capillariesC. Transformation of dermal fibroblasts into epidermal cellsD. Transformation of macrophages into epidermal cellsE. Transformation of melanocytes into epidermal cells

The correct answer is A. The dermis contains skin appendages (e.g., hair follicles), which containepithelial stem cells. In the process of healing a large area where the epidermis has been lost but thedermis is intact, re-epithelialization occurs by growth of epidermal cells from the underlying skinappendages, as well as from the intact epidermis along the wound edges. Physiologically, the dermis liesbeneath the epidermis. It has two major components, a superficial papillary layer and a deeper reticularlayer. The papillary layer contains the capillaries and the sensory neurons, which supply the surface of theskin. The reticular layer consists of an interwoven meshwork of dense irregular connective tissue.

None of the other cell types are known to directly contribute to the regeneration of epidermis overabraded skin.


An otherwise healthy student taking no medications is concerned because he has noticed several painlessuniform "large bumps" at the back of his tongue. These are most likely

A. aphthous ulcersB. candidal coloniesC. circumvallate papillaeD. filiform papillaeE. fungiform papillae

The correct answer is C. The large bumps at the back of his tongue are circumvallate papillae. Theseare large circular structures surrounded by moat-like depressions. The lateral surfaces of these papillaecontain taste buds. There are also small serous-only salivary glands in these papillae.

Aphthous ulcers (choice A) are small, white, or red mouth lesions.

Candidal colonies (choice B) appear in thrush, which occurs more commonly in the immunocompromisedhost or in those taking antibacterial drugs. You are told that the patient is healthy and not takingmedications, making this condition unlikely.

Filiform papillae (choice D) are the most numerous papillae of the tongue. They are small, elongatedcones that create the tongue's rough texture. They do not contain taste buds.

Fungiform papillae (choice E) are mushroom-shaped structures scattered among the filiform papillae.They frequently contain taste buds. They are intermediate in size between filiform and circumvallatepapillae.


Attempts to straighten out a flexed thigh cause great pain in a patient with appendicitis. This is due to theposition of the appendix near which muscle?

A. Adductor magnusB. Biceps femorisC. Gluteus maximusD. GracilisE. Psoas major

The correct answer is E. The path of the psoas major lies in the retroperitoneum and comes close tothe appendix. Acute appendicitis can cause either infection or a sympathetic inflammation of the psoas.This produces clinically a "positive psoas sign," in which attempts to straighten the patient's flexed (torelieve pain) hip produce sometimes marked exacerbation of the pain. None of the other muscles listedpass near the appendix.


Which of the following structures does the fetal allantoic duct become in the adult?

A. CloacaB. Medial umbilical ligamentC. UrachusD. UreterE. Urethra

The correct answer is C. The urachus is a fibrous remnant that extends from the umbilicus to theurinary bladder. It is also known as the median umbilical ligament of the anterior abdominal wall.

The cloaca (choice A) is the primitive, endoderm-lined region that receives the terminal portion of thehindgut. It is later subdivided into urogenital and anal areas.

The medial umbilical ligament (choice B) is a paired structure located deep to the peritoneum of theanterior abdominal wall. It is formed by the obliterated umbilical artery.

The ureter (choice D) is the muscular tube that conveys urine from the kidney to the urinary bladder.

The urethra (choice E) is the passageway that carries urine from the bladder to the perineum.


The smooth part of the right atrium derives from which of the following embryonic structures?

A. Bulbus cordisB. Primitive atriumC. Primitive ventricleD. Sinus venosusE. Truncus arteriosus

The correct answer is D. The smooth part of the right atrium (the sinus venarum) is derived from thesinus venosus. The coronary sinus and the oblique vein of the left atrium also derive from the sinusvenosus.

The bulbus cordis (choice A) gives rise to the smooth part of the right ventricle (conus arteriosus) andthe smooth part of the left ventricle (aortic vestibule).

The primitive atrium (choice B) gives rise to the trabeculated part of the right and left atria.

The primitive ventricle (choice C) gives rise to the trabeculated part of the right and left ventricles.

The truncus arteriosus (choice E) gives rise to the proximal part of the aorta and the proximal part of thepulmonary artery.


Microscopic examination of a PAS-stained histological section of a Graafian follicle demonstrates a brightreddish-pink, acellular ring around the ovum. Which of the following terms most accurately describes thisring?

A. Corona radiataB. Cumulus oophorusC. Theca externaD. Theca internaE. Zona pellucida

The correct answer is E. The ring described is the zona pellucida, which surrounds the ovum. The zonapellucida is rich in polysaccharides and glycoproteins and consequently stains brightly pink or red with PASstain. Binding of the sperm cell membrane to the zona pellucida triggers the acrosome reaction, duringwhich acrosomal enzymes are released that digest the zona pellucida, allowing the spermatozoon tocontact and fuse with the ovum cell membrane. Anatomically, as layers of granulosa cells develop aroundthe primary oocyte, microvilli from the surrounding granulosa cells intermingle with cells of the primaryoocyte. The microvilli are surrounded by a layer of glycoproteins, and the entire region is called the zonapellucida.

The follicular cells immediately outside the zona pellucida form the corona radiata (choice A). The largercumulus oophorus (choice B) is the hill of follicular cells that surrounds the ovum.

The theca interna (choice D) and externa (choice C) are formed from the connective tissue surroundingthe follicle.


Following a surgical procedure on the right side of the neck, a patient can no longer raise his right armabove the horizontal position. The patient also cannot shrug his right shoulder. Which of the followingnerves was injured?

A. Axillary nerveB. Great auricular nerveC. Greater occipital nerveD. Spinal accessory nerveE. Transverse cervical nerve

The correct answer is D. The spinal accessory nerve crosses the posterior triangle of the neckimmediately deep to the investing fascia of the neck. This nerve innervates the trapezius muscle, which isresponsible for upward rotation and elevation of the scapula. A lesion of this nerve in the posterior triangleleads to paralysis of the trapezius. Without the ability to upwardly rotate the scapula, abduction andflexion of the arm above the horizontal plane is not possible. Also, shrugging of the shoulder is impairedwith paralysis of the trapezius muscle.

The axillary nerve (choice A) does not pass through the neck. It is a branch of the brachial plexus, and itleaves the axilla to innervate the deltoid and teres minor muscles.

The great auricular nerve (choice B) and transverse cervical nerve (choice E) are branches of thecervical plexus, which provide cutaneous innervation to the skin of the neck. No muscles are innervated bythese nerves.

The greater occipital nerve (choice C) is the dorsal ramus of the second cervical spinal nerve. It providescutaneous innervation to the skin of the back of the head. No muscles are innervated by this nerve.


Zygomycosis, a destructive fungal infection of the sinuses, is likely to reach the brain by which of thefollowing routes?

A. Cavernous sinusB. External carotid arteryC. Internal carotid arteryD. Superior sagittal sinusE. Superior vena cava

The correct answer is A. This question requires knowledge of pathophysiology with a basicunderstanding of anatomy. The cavernous sinuses are located on either side of the body of the sphenoidbone and become a potential route of infection because they receive blood both from the face (via theophthalmic veins and sphenoparietal sinus) and from some of the cerebral veins. The spread of infectioninto the cavernous sinus can produce either central nervous system (CNS) infection or cavernous sinusthrombosis, both of which are potentially fatal.

The route from the face to the brain is not arterial (choices B and C).

The superior sagittal sinus (choice D) is located in the falx cerebri and drains venous blood from thebrain to other dural sinuses, from which it eventually drains into the jugular vein. Zygomycosis does notreach the brain by way of the superior sagittal sinus.

The superior vena cava (choice E) drains blood from the upper part of the body into the heart.


A surgeon inadvertently sections the recurrent laryngeal nerve during a procedure. Which of the followingmuscles would retain its innervation subsequent to this injury?

A. CricothyroidB. Lateral cricoarytenoidC. Posterior cricoarytenoidD. ThyroarytenoidE. Vocalis

The correct answer is A. The recurrent laryngeal nerve is a branch of the vagus nerve, whichinnervates all of the intrinsic laryngeal muscles, except for the cricothyroid muscle. The cricothyroid isattached to the cricoid cartilage and the thyroid cartilage; contraction of this muscle tends to stretch andadduct the vocal ligament. The cricothyroid is innervated by the external laryngeal nerve.

The lateral cricoarytenoid muscle (choice B) is innervated by the recurrent laryngeal nerve and isattached to the cricoid cartilage and the arytenoid cartilage. Its contraction causes adduction of the vocalligament.

The posterior cricoarytenoid muscle (choice C) is innervated by the recurrent laryngeal nerve and isattached to the cricoid cartilage and the arytenoid cartilage. Its contraction causes abduction of the vocalligament.

The thyroarytenoid muscle (choice D) is innervated by the recurrent laryngeal nerve and is attached tothe thyroid cartilage and the arytenoid cartilage. Its contraction causes slackening of the vocal ligament.

The vocalis muscle (choice E) is the most medial part of the thyroarytenoid muscle. It attaches to eitherthe thyroid cartilage and the vocal ligament, or the arytenoid cartilage and the vocal ligament. It isinnervated by the recurrent laryngeal nerve. Its contraction causes tension on segments of the vocalligament.


As a result of a viral infection, a patient has swelling of the left facial nerve within the facial canal. Thepatient's face appears asymmetrical, and he complains that saliva drips from his mouth while he ischewing. Paralysis of which of the following muscles accounts for these symptoms?

A. BuccinatorB. MasseterC. PalatoglossusD. PalatopharyngeusE. Temporalis

The correct answer is A. Compression of the facial nerve within the facial canal may result in facialpalsy (Bell's palsy). Because the muscles on one side of the face are paralyzed, the face appearsasymmetrical. The buccinator muscle, which is located within the cheek and is innervated by the facialnerve, functions to hold food against the teeth while it is being chewed. Paralysis of this muscle can resultin food and saliva accumulating between the teeth and the cheek. The buccinator originates from thealveolar processes of the maxilla and mandible. It inserts into the fibers of the obicularis oris.

The masseter and temporalis muscles (choices B and E) are innervated by the mandibular division of thetrigeminal nerve. These muscles of mastication function to elevate the mandible.

The palatoglossus (choice C) and palatopharyngeus (choice D) muscles are innervated by the vagusnerve. The palatoglossus, with its mucosal covering, forms the palatoglossal fold (anterior pillar of thefauces), immediately anterior to the palatine tonsil. This muscle functions to draw the tongue and softpalate closer together, as occurs during swallowing. The palatopharyngeus, with its mucosal covering,forms the palatopharyngeal fold (posterior pillar of the fauces), which is immediately posterior to thepalatine tonsil. This muscle causes elevation of the pharynx, as occurs during swallowing.


Biopsy demonstrates epithelial metaplasia. Which of the following cell types was most likely observed inthe involved areas?

A. Ciliated columnar epitheliumB. Cuboidal epitheliumC. Keratinizing squamous epitheliumD. Nonciliated columnar epitheliumE. Nonkeratinizing squamous epithelium

The correct answer is D. The medical condition is Barrett's esophagus, in which the normallynonkeratinizing squamous epithelium (choice E) of the esophagus undergoes metaplasia to gastric orintestinal-like epithelium composed of nonciliated columnar epithelial cells. Barrett's esophagus typicallydevelops in the setting of chronic gastroesophageal reflux and significantly increases the risk of laterdevelopment of adenocarcinoma of the distal esophagus.

Ciliated columnar epithelium (choice A) is found in the respiratory tract.

Cuboidal epithelium (choice B) is found in the kidney, peritoneal lining, and pleural lining.

Keratinizing squamous epithelium (choice C) is found in skin.

Nonkeratinizing squamous epithelium (choice E), in addition to being the normal epithelium of theesophagus, is found in mouth, nose, and vagina.


Hirschsprung's disease indicates a developmental abnormality in which of the following embryonic tissues?

A. EctodermB. EndodermC. Neural crestD. Neural ectodermE. Splanchnic mesoderm

The correct answer is C. The baby has Hirschsprung's disease, which is due to an absence of ganglioncells in the wall of the colon. Neural crest cells contribute to the formation of many adult structures.Among these are all of the postganglionic neurons of the autonomic nervous system and the sensoryneurons of the peripheral nervous system.

Ectoderm (choice A) forms the epidermis of the skin and the parenchymal cells of glands associated withthe skin such as the sweat glands, sebaceous glands, and mammary glands.

Endoderm (choice B) forms the epithelial lining of the gut tube and the parenchymal cells of glandsassociated with the gut tube, such as the liver and pancreas.

Neural ectoderm (choice D) forms the central nervous system, the somatic motor neurons of theperipheral nervous system, and the preganglionic neurons of the autonomic nervous system.

Splanchnic mesoderm (choice E) forms the visceral peritoneum, visceral pleura, visceral pericardium, andthe stroma and muscle of the wall of the gut, among other structures.


Despite blockage of the celiac trunk, the organs receiving their blood supply from the trunk continue tooperate normally. This is due to anastomoses between which vessels?

A. Left gastroepiploic artery and right gastroepiploic arteryB. Left gastroepiploic artery and right gastroepiploic arteryC. Proper hepatic artery and gastroduodenal arteryD. Right colic artery and middle colic arteryE. Superior pancreaticoduodenal artery and inferior pancreaticoduodenal artery

The correct answer is E. The superior pancreaticoduodenal artery is a branch of the gastroduodenalartery, which is a branch of the common hepatic artery, itself a branch of the celiac trunk. The inferiorpancreaticoduodenal artery is a branch of the superior mesenteric artery. Occlusion of the celiac trunkwould allow blood from the superior mesenteric artery to reach the branches of the celiac trunk via theconnections between the superior and inferior pancreaticoduodenal arteries.

The left gastric and right gastric arteries (choice A) both receive their blood from the celiac trunk. Theleft gastric artery is a direct branch of the celiac trunk. The right gastric artery is usually a branch of theproper hepatic artery, which is a branch of the common hepatic artery (a branch of the celiac trunk).

The left and right gastroepiploic arteries (choice B) both receive their blood supply from the celiac trunk.The left gastroepiploic artery is a branch of the splenic artery, which is a branch of the celiac trunk. Theright gastroepiploic artery is a branch of the gastroduodenal artery, which is a branch of the commonhepatic artery (a branch of the celiac trunk).

The proper hepatic and gastroduodenal arteries (choice C) are branches of the common hepatic artery,which is a branch of the celiac trunk.

The right colic and middle colic arteries (choice D) are both branches of the superior mesenteric artery.


Damage to which of the following structures might produce hair cell loss?

A. Basilar membraneB. Organ of CortiC. Reissner's membraneD. Scala tympaniE. Scala vestibuli

The correct answer is B. Hearing is the detection of sound, which consists of pressure waves conductedthrough air or water. The receptors of the cochlear duct provide us with a sense of hearing that allows usto detect the quietest whisper and yet remain functional in a crowded, noisy environment. The organ ofCorti contains hair cells from the cochlear branch of the vestibulocochlear nerve (CN VIII). These cells reston the basilar membrane (choice A), which separates the scala tympani (choice D) from the scalamedia. The hair cells are embedded in the tectorial membrane, and movement of the basilar membranebelow the cells causes the hairs to bend, which generates action potentials. The tectorial membrane thatlies on the hair cells does not form a boundary between the different scala; the membrane separating thescala media from the scala vestibuli (choice E) is Reissner's (vestibular) membrane (choice C).


Which of the following locations in the embryo later forms the dorsal horn of the spinal cord?

A. Alar plateB. Basal plateC. Neural crestD. Rostral end of neural tubeE. Sulcus limitans

The correct answer is A. The spinal cord arises from the caudal end of the neural tube. Duringdevelopment, an alar and a basal plate is formed, separated by a longitudinal groove called the sulcuslimitans (choice E). The alar plate forms the dorsal (posterior) part of the spinal cord and becomes thesensory or afferent portion of the cord. The basal plate (choiceB) is the ventral (anterior) part of the cordand becomes the motor, or efferent, portion of the spinal cord and therefore would contain anterior horncells.

The neural crest (choice C) develops into multipolar ganglion cells of autonomic ganglia, pseudounipolarcells of spinal and cranial nerve ganglia, leptomeningeal cells, Schwann cells, melanocytes, chromaffincells of the adrenal medulla, and odontoblasts.

The brain forms from the rostral end of the neural tube (choice D).


From which of the following fetal vessels do the umbilical arteries arise?

A. AortaB. Carotid arteriesC. Ductus arteriosusD. Iliac arteriesE. Pulmonary arteries

The correct answer is D. The paired umbilical arteries arise from the iliac arteries. They supplyunoxygenated fetal blood to the placenta. The single umbilical vein takes the newly oxygenated fetal bloodfrom the placenta to the liver and then to the inferior vena cava via the ductus venosus. Near the level ofvertebra L4, the terminal segment of the abdominal aorta divides to form the right and left common iliacarteries. These arteries carry blood to the pelvis and lower limbs. As these arteries travel along the innersurface, they descend behind the cecum and sigmoid colon, where each divides to form the internal iliacartery and external iliac artery.


A mass in the anterior midline of the neck, slightly above the larynx is mobile and elevates uponprotrusion of the tongue. This mass is most likely a cyst that developed from which of the followingembryonic structures?

A. First pharyngeal cleftB. First pharyngeal pouchC. Second pharyngeal cleftD. Second pharyngeal pouchE. Thyroglossal duct

The correct answer is E. The thyroglossal duct develops as an evagination of the floor of the pharynx inthe region where the tongue develops. The adult foramen cecum of the tongue marks the site of thisevagination. The distal end of this duct normally forms the thyroid gland; the proximal part of the ductnormally degenerates. Failure of a part of the duct to degenerate may lead to a thyroglossal duct cyst or amedian cervical cyst, as seen in this patient.

The first pharyngeal cleft (choice A) forms the external ear canal. This cleft normally remains patent.

The first pharyngeal pouch (choice B) forms the middle ear cavity and the auditory tube. This pouchnormally remains patent.

The second pharyngeal cleft (choice C) normally does not remain patent. It is typically covered over bythe overgrowth of the second pharyngeal arch. If part of this pouch does remain patent, it may form alateral cervical cyst, which is seen on the lateral side of the neck along the anterior border of thesternocleidomastoid muscle.

The second pharyngeal pouch (choice D) forms the tonsillar fossa of the pharynx. The pharyngealmucosa in this area arises from the endoderm of the pouch. Ingrowth of mesoderm cells results in theformation of the palatine tonsil.


Which of the following sites contains striated muscle that is not under voluntary control?

A. BladderB. ColonC. EsophagusD. GallbladderE. Stomach

The correct answer is C. Striated (skeletal) muscle not under voluntary control is an unusual feature ofthe upper and middle thirds of the esophagus. The middle third of the esophagus contains roughly halfstriated and half smooth muscle; the lower third contains only smooth muscle. All the other structureslisted in the answer choices contain smooth muscle.

As a side note, cardiac muscle cells do not rely on nerve activity to start a contraction. Instead, specializedpacemaker cells establish a regular rate of contraction. Because these pacemaker cells regulate the heartand the central nervous system does not, cardiac muscle is also considered striated, involuntary muscle.


An ulcer damages an artery supplying the area of the greater curvature of the stomach. Which artery isinvolved?

A. Left gastricB. Left gastroepiploicC. Right gastricD. Right gastroepiploicE. Short gastric

The correct answer is D. The right gastroepiploic artery, off the gastroduodenal artery, supplies theright half of the greater curvature of the stomach and could be directly affected by ulceration of thegreater curvature of the stomach at a site this close (4 cm) to the pyloric sphincter.

The left gastric artery (choice A), off the celiac trunk, supplies the left half of the lesser curvature of thestomach.

The left gastroepiploic artery (choice B), off the splenic artery, supplies the left half of the greatercurvature of the stomach. Although it anastomoses with the right gastroepiploic artery, it is unlikely thatthis artery would be directly damaged by ulceration of the stomach near the pyloric sphincter.

The right gastric artery (choice C), off the proper hepatic artery, supplies the right half of the lessercurvature of the stomach.

The short gastric artery (choice E), actually one of several (4 to 5) short gastric arteries, off the splenicartery (occasionally the left gastroepiploic), supplies the fundus of the stomach, which is the most distantfrom the pylorus.


An elderly patient has had multiple small strokes lending to an absence of the gag reflex. These findingssuggest involvement of the nucleus of which of the following cranial nerves?

A. Facial (VII)B. Glossopharyngeal (IX)C. Hypoglossal (XII)D. Spinal accessory (XI)E. Vestibulocochlear (VIII)

The correct answer is B. Cranial nerve IX is the glossopharyngeal nerve, which has a nucleus in themedulla and is necessary for the gag reflex. The gag reflex is elicited by touching either side of theposterior pharynx with a tongue blade, producing bilateral elevation of the palate and bilateral contractionof the pharyngeal muscles. The afferent of this reflex arc consists of the ipsilateral glossopharyngealnerve, while the vagus nerve, bilaterally, supplies the efferent limb. Although the glossopharyngeal nervemay seem to be one of the less important cranial nerves, you should remember to test for its function, asa loss of gag reflex can lead to the patient's death secondary to an aspiration pneumonia. Theglossopharyngeal nerve is a mixed sensory and motor nerve to the head and neck. It originates from theposterior 1/3 of the tongue, pharynx, palate, and carotid arteries of the neck. Its destination includessensory nuclei of the medulla oblongata, as well as the pharyngeal muscles involved in swallowing.

Cranial nerve VII (choice A) is the facial nerve, which supplies motor function to the face, but it does notsupply the oropharynx.

Cranial nerve XII (choice C) is the hypoglossal nerve, which supplies the intrinsic and most extrinsicmuscles of the tongue. It is not involved in the gag reflex.

Cranial nerve XI (choice D) is the spinal accessory nerve, which supplies the trapezius andsternocleidomastoid.

Cranial nerve VIII (choice E) is the vestibulocochlear nerve, responsible for hearing and equilibrium.


Which of the following respiratory system components is derived from neural crest?

A. Endothelial cellsB. Epithelium of primary bronchiC. Laryngeal cartilageD. Tracheal glandsE. Type I pneumocytes

The correct answer is C. Laryngeal cartilages are derived from neural crest. The larynx is composed ofthree cartilages that form the "body of the larynx": the thyroid cartilage, the cricoid cartilage, and theepiglottis. The larynx also contains three pairs of smaller hyaline cartilages: the arytenoid, corniculate, andcuneiform cartilages.

The endothelial cells (choice A), in the simple squamous epithelium that lines the pulmonary capillaries,are derived from visceral mesoderm.

The epithelial lining of primary bronchi (choice B) is derived from endoderm.

Tracheal glands (choice D) and epithelium both derive from endoderm.

Type I pneumocytes (choice E) are derived from endoderm.


The extraocular muscles are derived from which of the following structures?

A. Branchial archesB. Optic cup ectodermC. SomitesD. SomitomeresE. Splanchnic mesoderm

The correct answer is D. The somitomeres are specialized masses of mesoderm found in the headregion that give rise to the muscles of the head. The extraocular muscles are derived from somitomeres 1,2, 3, and 5.

The branchial arches (choice A) give rise to muscles of mastication (arch 1), muscles of facial expression(arch 2), and muscles of the pharynx and larynx (arches 3-6), as well as additional small muscles.

The optic cup ectoderm (choice B) gives rise to the muscles of the iris (sphincter and dilator pupillae).These are the only muscles not formed from mesoderm.

Somites (choice C) give rise to the inferior muscles of the neck.

Splanchnic mesoderm (choice E) gives rise to smooth muscle of the viscera and the heart muscle.


Injury at the lower border of a rib will most likely damage which structure?

A. intercostal arteryB. intercostal nerveC. intercostal veinD. internal intercostal muscle

The correct answer is B. The three structures in the intercostal space are, from superior to inferior, theintercostal vein, artery, and nerve. The proper site for insertion of an intercostal drain is superior to a rib,not directly at the level of the superior border but slightly higher to avoid the collateral branches of thenerve, artery, and vein. The nerve is the most inferior structure and thus most likely to be damaged bythe drain (producing an anesthetic dermatome). In addition, the nerve is the least protected by the costalgroove.

The intercostal artery (choice A) is the middle structure and thus is not the most likely to be damaged.

The intercostal vein (choice C) is the most superior structure and is thus the least likely to be damaged.In addition, the vein is the structure best protected by the costal groove (the further superior thestructure, the more protected by the costal groove).

The internal intercostal fibers (choice D) will tend to be separated by the drain. In addition, the internalintercostal muscle is membranous (internal intercostal membrane) posteriorly, from the neck of the rib toits angle; therefore, many drains, when inserted, will not even pass through a layer of internal intercostalmuscle.


A CT scan reveals a small tumor at the cerebellopontine angle of the brain. Which of the following nervesis most likely to be affected by this tumor?

A. Facial nerveB. Glossopharyngeal nerveC. Optic nerveD. Trigeminal nerveE. Vagus nerve

The correct answer is A. The facial nerve and the vestibulocochlear nerves emerge from the brain stemat the cerebellopontine angle. These are the two nerves that will be initially affected by a tumor in thisregion. The entire anatomy of the facial nerve is as follows: the facial nerve originates from the tastereceptors on the anterior 2/3 of the tongue (sensory) and from nuclei of the pons (motor). It passesthrough the internal acoustic canal of the temporal bone to reach the stylomastoid foramen.

The glossopharyngeal and vagus nerves (choices B and E) emerge from the brain stem at thepostolivary sulcus. This is caudal to the cerebellopontine angle.

The optic nerve (choice C) exits from the optic chiasm on the ventral surface of the diencephalon. This isrostral to the cerebellopontine angle.

The trigeminal nerve (choice D) emerges from the brain stem at the anterolateral surface of the pons.This is rostral and ventral to the cerebellopontine angle.


A patient is unable to close her right eye. Physical examination reveals weakness of the right orbicularisoculi. Which of the following additional symptoms would likely also be present?

A. Blurred visionB. HyperacusisC. Inability to chewD. Inability to feel the faceE. Inability to shrug the shoulder

The correct answer B. The facial nerve innervates the muscles of facial expression. The visceral motorportion innervates the lacrimal gland and nasal mucous glands via the sphenopalatine ganglion. Thesubmandibular and sublingual salivary glands are innervated via the submandiublar ganglion. This patienthas a lesion of the facial nerve (VII), which leads to an inability to close the ipsilateral eye because ofdamaged motor fibers to the orbicularis oculi. This patient would also lose her corneal reflex on that sidebecause of an inability to blink and would have ipsilateral paralysis of the muscles of facial expressiondistal to the lesion. If the lesion affected the facial nerve more proximally, additional findings would behyperacusis (increased sensitivity to sound because of stapedius muscle paralysis), lack of taste sensationin the anterior two-thirds of the tongue, and disturbed lacrimation and salivation.

Blurred vision (choice A) could occur with lesions of the oculomotor (CN III), abducens (CN VI), ortrochlear (CN IV) nerves, which innervate the extraocular muscles. CN III innervates the medial rectus,inferior rectus, superior rectus, and inferior oblique muscles. CN VI innervates the lateral rectus and CN IVinnervates the superior oblique.

An inability to chew (choice C) would probably be the result of a lesion of the trigeminal nerve (CN V).Motor fibers of CN V innervate the muscles of mastication (temporalis, masseter, and medial and lateralpterygoid muscles), and a lesion of these fibers may cause the jaw to deviate to the side of the weakmuscles.

An inability to feel the face (choice D) would also be the result of a CN V lesion. This lesion could resultin the ipsilateral loss of general sensation of the face and also of the mucous membranes of the oral andnasal cavities.

A lesion of the accessory nerve (CN XI) would cause paralysis of the trapezius muscle, which results in asagging of the shoulder and a weakness in attempting to shrug the shoulder (choice E).


A patient received a severe blow to the lateral side of the head, resulting in an epidural hematoma. Whichof the following blood vessels was most likely torn?

A. Anterior cerebral arteryB. Middle cerebral arteryC. Middle meningeal arteryD. Superficial temporal arteryE. Superior cerebral vein

The correct answer is C. The middle meningeal artery is in the interior of the lateral portion of thecranial cavity, embedded in the periosteal (outer) layer of the dura. A tear of this artery results in bloodentering the potential space between the outer dural layer and the skull (epidural space), causing anepidural hematoma.

The anterior cerebral artery and middle cerebral artery (choices A and B) lie on the surface of the brain.The anterior cerebral arteries supply the medial surface of the cerebral hemispheres, and the middlecerebral arteries supply the lateral surface of the cerebral hemispheres. A tear of either of these arterieswould result in blood entering the subarachnoid space (subarachnoid hemorrhage).

The superficial temporal artery (choice D) is a branch of the external carotid artery and is external to theskull. This artery supplies the skin and other tissue of the temple region.

The superior cerebral veins (choice E) drain the cerebral hemisphere and enter the superior sagittalsinus. A tear of these veins results in blood entering the potential space between the dura and arachnoid(subdural space), causing a subdural hematoma.


The x-ray of a child's arm after a fall appears to show a fracture near, but not at, the distal end of theulna. Before diagnosing a fracture, you should also consider the possibility that this is actually which of thefollowing?

A. Articular cartilageB. Epiphyseal plateC. PerichondriumD. Primary ossification centerE. Secondary ossification center

The correct answer is B. The epiphyseal plate of the bone contains cartilage that is radiolucent. Theplate in a bone that is not yet fully ossified can produce a "line" crossing the bone near the end. This maybe easily mistaken for a fracture by the inexperienced. Anatomically, the epiphyseal plate separates theepiphysis from the diaphysis.

Articular cartilage (choice A) is radiolucent, but occurs at the very tip of the long bones.

Perichondrium (choice C) is usually difficult to see on x-ray.

Primary (choice D) and secondary (choice E) ossification centers are radiopaque.


Which of the following embryonic structures gives rise to the adrenal cortex?

A. EctodermB. EndodermC. MesodermD. MesonephrosE. Neural crest cells

The correct answer is C. The mesoderm gives rise to the adrenal cortex. In addition, it also gives riseto connective tissue, cartilage, bone, muscle, blood and lymph vessels, kidneys, gonads, serousmembranes lining body cavities, and the spleen.

The ectoderm (choice A) gives rise to the central nervous system, peripheral nervous system, epidermisand its appendages, mammary glands, pituitary gland, tooth enamel, and the neural crest.

The endoderm (choice B) gives rise to the parenchyma of the tonsils, thyroid and parathyroid glands,thymus, liver, pancreas, the epithelial lining of the gastrointestinal and respiratory tracts, urinary bladder,urethra, and auditory tube.

The mesonephros (choice D) functions as an interim kidney in the embryo.

The neural crest cells (choice E) give rise to cells of the spinal and cranial nerves, autonomic ganglia,melanocytes, leptomeninges, connective tissue and bone of branchial arch origin, and the adrenal medulla.


The major structural component of the sperm flagellum is the:

A. microtubuleB. microfilamentC. actin filamentD. mysosin filamentE. ciliary body

The correct answer is choice A. This is a basic histological question of a type found commonly onNBDE, which asks about basic cellular organelles and structures. The sperm cell flagellum is notable for a9+2 arrangement of fibers formed from microtubules. The 9 single fibers form a circular ring in crosssection around the 2 doubled fibers in the center. One of the significant facts about the fibers is that theyare composed of microtubules, made up of tubulin. The other significant fact is that all eucaryotic flagellaand cilia have this same structure (for example, cilia form the tracheal lining). Note that procaryotic(bacterial) flagellea do NOT share this structure.


In cases of dysphagia where the esophagus is compressed, which structure would be most likely to causethe compression?

A. Left atriumB. Left ventricleC. Pulmonary trunkD. Right atriumE. Right ventricle

The correct answer is A. The left atrium forms most of the posterior wall of the heart. The esophaguspasses immediately posterior to the heart. Enlargement of the left atrium may compress the esophagusand cause dysphagia. Anatomically, the esophagus begins posterior to the cricoid cartilage, at the level ofvertebrum C6. From this point, it descends toward the thoracic cavity posterior to the trachea, passesinferiorly along the dorsal wall of the mediastinum, and enters the abdominopelvic cavity through anopening in the diaphragm, the diaphragmatic hiatus.

The left ventricle (choice B) forms most of the left border of the heart and most of the diaphragmaticsurface of the heart. The left ventricle is not related to the esophagus.

The pulmonary trunk (choice C) emerges from the right ventricle on the anterior surface of the heart.The pulmonary trunk is not related to the esophagus.

The right atrium (choice D) forms the right border of the heart. It is not related to the esophagus.

The right ventricle (choice E) forms most of the anterior wall of the heart and a small portion of thediaphragmatic surface of the heart. It is not related to the esophagus.


Which of the following tissues normally has the highest percentage

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Anatomy 1