BRS Gross Anatomy Semester 1 Flashcards
A 24-year-old carpenter suffers a crush injury of his entire little finger. Which of the following muscles is most likely to be spared?
(A) Flexor digitorum profundus
(B) Extensor digitorum
(C) Palmar interossei
(D) Dorsal interossei
(E) Lumbricals
The answer is D. The dorsal interossei are abductors of the fingers. The little finger has no attachment for the dorsal interosseous muscle because it has its own abductor. Therefore, the dorsal interosseous muscle is not affected. Other muscles are attached to the little finger; thus, they are injured.
A young toddler presents to her pediatrician with rather new onset of bowel and bladder dysfunction and loss of the lower limb function. Her mother had not taken enough folic acid (to the point of a deficiency) during her pregnancy. On examination, the child has protrusion of the spinal cord and meninges and is diagnosed with which of the following conditions?
(A) Spina bifida occulta
(B) Meningocele
(C) Meningomyelocele
(D) Myeloschisis
(E) Syringomyelocele
The Answer is C. Meningomyelocele is protrusion of the meninges and spinal cord through the unfused arch of the vertebra. A sufficient amount of folic acid during pregnancy is shown to prevent these kinds of neural tube defects. Spina bifida occulta is failure of the vertebral arch to fuse (only bony defect). Meningocele is protrusion of the meninges through the defective vertebral arch. Syringomyelocele is protrusion of the meninges and a pathologic tubular cavity in the spinal cord or brain.
After a 26-year-old man’s car was broadsided by a large truck, he is brought to the emergency department with multiple fractures of the transverse processes of the cervical and upper thoracic vertebrae. Which of the following muscles might be affected?
(A) Trapezius
(B) Levator scapulae
(C) Rhomboid major
(D) Serratus posterior superior
(E) Rectus capitis posterior major
The Answer is B. The levator scapulae arise from the transverse processes of the upper cervical vertebrae and inserts on the medial border of the scapula. The other muscles are attached to the spinous processes of the vertebrae.
A 27-year-old paratrooper lands on a pine tree. Consequently, preganglionic parasympathetic nerves leaving the central nervous system are lacerated. Which of the following structures contain cell bodies of the damaged nerve fibers?
(A) Cervical and sacral spinal cord
(B) Cervical and thoracic spinal cord
(C) Brain stem and cervical spinal cord
(D) Thoracic and lumbar spinal cord
(E) Brain stem and sacral spinal cord
The answer is E. Preganglionic neurons of the parasympathetic nervous system are located in the brain stem (cranial outflow) and sacral spinal cord segments S2 to S4 (sacral outflow). Preganglionic sympathetic neurons are located in the thoracic and lumbar spinal cord.
After an automobile accident, a back muscle that forms the boundaries of the triangle of auscultation and the lumbar triangle receives no blood. Which of the following muscles might be ischemic?
(A) Levator scapulae
(B) Rhomboid minor
(C) Latissimus dorsi
(D) Trapezius
(E) Splenius capitis
The Answer is C. The latissimus dorsi forms boundaries of the auscultation and lumbar triangles and receives blood from the thoracodorsal artery. The levator scapulae, rhomboid minor, and splenius capitis muscles do not form boundaries of these two triangles. The trapezius muscle forms a boundary of the auscultation triangle but not the lumbar triangle. The levator scapulae, rhomboid minor, and trapezius muscles receive blood from the transverse cervical artery. The splenius capitis muscle receives blood from the occipital and transverse cervical arteries.
A 7-year-old girl has difficulty breathing through her nose and is brought to her pediatrician. On examination, she is diagnosed with adenoids. Which of the following tonsils is enlarged?
(A) Palatine tonsil
(B) Pharyngeal tonsil
(C) Tubal tonsil
(D) Lingual tonsil
(E) Eustachian tonsil
The answer is B. The enlarged pharyngeal tonsil is called an adenoid. An adenoid obstructs passage of air from the nasal cavities through the choanae into the nasopharynx, thus causing difficulty in nasal breathing and phonation. The tubal tonsil is also called the eustachian tonsil. The palatine tonsil is called the faucial tonsil. The submerged tonsil is a palatine tonsil that is shrunken and atrophied and is partly or entirely hidden by the palatoglossal arch.
A 19-year-old woman complains of numbness of the nasopharynx after surgical removal of the adenoid. A lesion of which of the following nerves would be expected?
(A) Maxillary nerve
(B) Superior cervical ganglion
(C) External laryngeal nerve
(D) Glossopharyngeal nerve
(E) Vagus nerve
The answer is D. The glossopharyngeal nerve supplies sensory innervation to the mucosa of the upper pharynx, whereas the vagus nerve supplies sensory innervation to the lower pharynx and larynx. The maxillary nerve supplies sensory innervation to the face below the level of the eye and above the level of the upper lip and the palate and nasal mucosa. The superior cervical ganglion contributes to a formation of the pharyngeal plexus but contains no afferent fibers. The external laryngeal nerve innervates the cricothyroid and inferior pharyngeal constrictor muscles.
A 60-year-old man is unable to open his eye because of a rare neuromuscular disease. Which of the following muscles would most likely be paralyzed?
(A) Orbicularis oculi
(B) Orbicularis oris
(C) Frontalis
(D) Levator palpebrae superioris
(E) Superior rectus
The answer is D. The levator palpebrae superioris muscle opens the eye by elevating the upper eyelid. The orbicularis oculi closes the eye, the orbicularis oris closes the lips, the frontalis elevates the eyebrow, and the superior rectus elevates the eyeball.
A 24-year-old woman presents to her physician with weakness in flexing the hip joint and extending the knee joint. Which muscle is most likely involved in this scenario?
(A) Sartorius
(B) Gracilis
(C) Rectus femoris
(D) Vastus medialis
(E) Semimembranosus
The Answer is C. The rectus femoris flexes the thigh and extends the leg. The sartorius can flex both the hip and knee joints. The gracilis adducts and flexes the thigh and flexes the leg, the vastus medialis extends the knee joint, and the semimembranosus extends the hip joint and flexes the knee joint.
A patient experiences paralysis of the muscle that originates from the femur and contributes directly to the stability of the knee joint. Which of the following muscles is involved?
(A) Vastus lateralis
(B) Semimembranosus
(C) Sartorius
(D) Biceps femoris (long head)
(E) Rectus femoris
The Answer is A. The vastus lateralis muscles arise from the femur and all the other muscles originate from the hip (coxal) bone. The biceps femoris inserts on the fibula, and other muscles insert on the tibia; thus, all of them contribute to the stability of the knee joint.
A 65-year-old man with multiple vision problems comes to the local eye clinic. The pupillary light reflex can be eliminated by cutting which of the following nerves?
(A) Short ciliary, ophthalmic, and oculomotor nerves
(B) Long ciliary, optic, and short ciliary nerves
(C) Oculomotor, short ciliary, and optic nerves
(D) Optic and long ciliary nerves and ciliary ganglion
(E) Ophthalmic and optic nerves and ciliary ganglion
The answer is C. The efferent limbs of the reflex are involved in the pupillary light reflex (i.e., constriction of the pupil in response to illumination of the retina) and are composed of parasympathetic preganglionic fibers in the oculomotor nerve, parasympathetic fibers and ganglionic cells in the ciliary ganglion, and parasympathetic postganglionic fibers in the short ciliary nerves. The afferent limbs of this reflex are optic nerve fibers. The long ciliary nerves contain postganglionic sympathetic fibers. The ophthalmic nerve contains GSA fibers.
The police bring in a murder suspect who has been in a gunfight with a police officer. The suspect was struck by a bullet in the arm; his median nerve has been damaged. Which of the following symptoms is likely produced by this nerve damage?
(A) Waiter’s tip hand
(B) Claw hand
(C) Wrist drop
(D) Ape hand
(E) Flattening of the hypothenar eminence
The answer is D. Injury to the median nerve produces the ape hand (a hand with the thumb permanently extended). Injury to the radial nerve results in loss of wrist extension, leading to wrist drop. Damage to the upper trunk of the brachial plexus produces waiter’s tip hand. A claw hand and flattening of the hypothenar eminence or atrophy of the hypothenar muscles result from damage to the ulnar nerve.
A 17-year-old boy was stabbed during a gang fight, resulting in the transection of the obturator nerve. Which of the following muscles is completely paralyzed?
(A) Pectineus
(B) Adductor magnus
(C) Adductor longus
(D) Biceps femoris
(E) Semimembranosus
The Answer is C. The adductor longus is innervated by only the obturator nerve. Thus, injury here could completely paralyze the adductor longus. The pectineus is innervated by both the obturator and femoral nerves. The adductor magnus is innervated by both the obturator nerve and tibial part of the sciatic nerve. The biceps femoris is innervated by the tibial portion (long head) and common peroneal portion (short head) of the sciatic nerve. The semimembranosus is innervated by the tibial portion of the sciatic nerve.
A 24-year-old man falls from his motorcycle and lands in a creek. Death may result from bilateral severance of which of the following nerves?
(A) Trigeminal nerve
(B) Facial nerve
(C) Vagus nerve
(D) Spinal accessory nerve
(E) Hypoglossal nerve
The answer is C. Bilateral severance of the vagus nerve (CN X) causes a loss of reflex control of circulation because of an increase in heart rate and blood pressure; poor digestion results because of decreased gastrointestinal motility and secretion; and difficulty in swallowing, speaking, and breathing occurs because of paralysis of laryngeal and pharyngeal muscles. All of these effects may result in death. Bilateral severance of other nerves does not cause death.
A 21-year-old woman walks in with a shoulder and arm injury after falling during horseback riding. Examination indicates that she cannot adduct her arm because of paralysis of which of the following muscles?
(A) Teres minor
(B) Supraspinatus
(C) Latissimus dorsi
(D) Infraspinatus
(E) Serratus anterior
The answer is C. The latissimus dorsi adducts the arm, and the supraspinatus muscle abducts the arm. The infraspinatus and the teres minor rotate the arm laterally. The serratus anterior rotates the glenoid cavity of the scapula upward, abducts the arm, and elevates it above a horizontal position.
An automobile body shop worker has his middle finger crushed while working on a transmission. Which of the following muscles is most likely to retain function?
(A) Extensor digitorum
(B) Flexor digitorum profundus
(C) Palmar interosseous
(D) Dorsal interosseous
(E) Lumbrical
The answer is C. The extensor digitorum, flexor digitorum profundus, dorsal interosseous, and lumbrical muscles are attached to the middle digit, but no palmar interosseous muscle is attached to the middle digit.
A 24-year-old woman complains of weakness when she extends her thigh and rotates it laterally. Which of the following muscles is paralyzed?
(A) Obturator externus
(B) Sartorius
(C) Tensor fasciae latae
(D) Gluteus maximus
(E) Semitendinosus
The Answer is D. The gluteus maximus can extend and rotate the thigh laterally. The obturator externus rotates the thigh laterally. The sartorius can flex both the hip and knee joints. The tensor fasciae latae can flex and medially rotate the thigh. The semitendinosus can extend the thigh and medially rotate the leg.
A thoracic surgeon is going to collect a portion of the greater saphenous vein for coronary bypass surgery. He has observed that this vein runs
(A) Posterior to the medial malleolus
(B) Into the popliteal vein
(C) Anterior to the medial condyles of the tibia and femur
(D) Superficial to the fascia lata of the thigh
(E) Along with the femoral artery
The Answer is D. The greater saphenous vein ascends superficial to the fascia lata. It courses anterior to the medial malleolus and posterior to the medial condyles of the tibia and femur and terminates in the femoral vein by passing through the saphenous opening. The small saphenous vein drains into the popliteal vein. The greater saphenous vein does not run along with the femoral artery.
A 52-year-old woman slipped and fell and now complains of being unable to extend her leg at the knee joint. Which of the following muscles was paralyzed as a result of this accident?
(A) Semitendinosus
(B) Sartorius
(C) Gracilis
(D) Quadriceps femoris
(E) Biceps femoris
The Answer is D. The quadriceps femoris muscle includes the rectus femoris muscle and the vastus medialis, intermedialis, and lateralis muscles. They extend the leg at the knee joint. The semitendinosus, semimembranosus, and biceps femoris muscles (the hamstrings) extend the thigh and flex the leg. The sartorius and gracilis muscles can flex the thigh and the leg.
A 14-year-old boy hits his head on the asphalt road after falling off his skateboard. His radiograph reveals damage to the sella turcica. This is probably due to fracture of which of the following bones?
(A) Frontal bone
(B) Ethmoid bone
(C) Temporal bone
(D) Basioccipital bone
(E) Sphenoid bone
The answer is E. The sella turcica is part of the sphenoid bone and lies superior to the sphenoid sinus. Therefore, none of the other bones listed is fractured.
A 3-year-old girl is admitted to the hospital with pain and hearing defect. An MRI examination reveals that she has developmental defects in the auditory tube and middle ear cavity. Which of the following pharyngeal pouches is most likely developed abnormally?
(A) First pouch
(B) Second pouch
(C) Third pouch
(D) Fourth pouch
(E) Second and fourth pouches
The answer is A. The first pharyngeal pouch gives rise to the auditory tube and middle ear cavity. The second pouch forms the palatine tonsils. The third pouch gives rise to the inferior parathyroid gland and thymus. The fourth pouch develops into the superior parathyroid gland and ultimobranchial body of the thyroid.
A 16-year-old boy fell from a motorcycle, and his radial nerve was severely damaged because of a fracture of the midshaft of the humerus. Which of the following conditions would most likely result from this accident?
(A) Loss of wrist extension leading to wrist drop
(B) Weakness in pronating the forearm
(C) Sensory loss over the ventral aspect of the base of the thumb
(D) Inability to oppose the thumb
(E) Inability to abduct the fingers
The answer is A. Injury to the radial nerve results in loss of wrist extension, leading to wrist drop. The median nerve innervates the pronator teres, pronator quadratus, and opponens pollicis muscles and the skin over the ventral aspect of the thumb. The ulnar nerve innervates the dorsal interosseous muscles, which act to abduct the fingers.
An elderly man at a nursing home is known to have degenerative brain disease. When cerebrospinal fluid (CSF) is withdrawn by lumbar puncture for further examination, which of the following structures is most likely penetrated by the needle?
(A) Pia mater
(B) Filum terminale externum
(C) Posterior longitudinal ligament
(D) Ligamentum flavum
(E) Annulus fibrosus
The Answer is D. The cerebrospinal fluid (CSF) is located in the subarachnoid space, between the arachnoid layer and the pia mater. In a lumbar puncture, the needle penetrates the skin, fascia, ligamentum flavum, epidural space, dura mater, subdural space, and arachnoid mater. The pia mater forms the internal boundary of the subarachnoid space; thus, it cannot be penetrated by needle. The posterior longitudinal ligament lies anterior to the spinal cord; thus, it is not penetrated by the needle. The filum terminale externum is the downward prolongation of the spinal dura mater from the second sacral vertebra to the dorsum of the coccyx. The annulus fibrosus consists of concentric layers of fibrous tissue and fibrocartilage surrounding and retaining the nucleus pulposus of the intervertebral disk, which lies anterior to the spinal cord.
A 29-year-old man comes in with a stab wound, cannot raise his arm above horizontal, and exhibits a condition known as “winged scapula.” Which of the following structures of the brachial plexus would most likely be damaged?
(A) Medial cord
(B) Posterior cord
(C) Lower trunk
(D) Roots
(E) Upper trunk
The answer is D. Winged scapula is caused by paralysis of the serratus anterior muscle that results from damage to the long thoracic nerve, which arises from the roots of the brachial plexus (C5–C7).
A patient has weakness when flexing both her thigh and leg. Which of the following muscles is most likely injured?
(A) Rectus femoris
(B) Semitendinosus
(C) Biceps femoris
(D) Sartorius
(E) Adductor longus
The Answer is D. The sartorius can flex and rotate the thigh laterally, and flex and rotate the leg medially. The rectus femoris flexes the thigh and extends the leg. The semimembranosus extends the thigh and flexes and rotates the leg medially. The biceps femoris extends the thigh and flexes and rotates the leg laterally. The adductor longus adducts and flexes the thigh.
A patient presents with sensory loss on adjacent sides of the great and second toes and impaired dorsiflexion of the foot. These signs probably indicate damage to which of the following nerves?
(A) Superficial peroneal
(B) Lateral plantar
(C) Deep peroneal
(D) Sural
(E) Tibial
The Answer is C. The deep peroneal nerve supplies the anterior muscles of the leg, including the tibialis anterior, extensor hallucis longus, extensor digitorum longus, and peroneus tertius muscles, which dorsiflex the foot. The medial branch of the deep peroneal nerve supplies the skin of adjacent sides of the great and second toes, whereas the lateral branch supplies the extensor digitorum brevis and extensor hallucis brevis. The superficial peroneal nerve innervates the peroneus longus and brevis, which plantar flexes the foot, and supplies the skin on the side of the lower leg and the dorsum of the ankle and foot. The tibial nerve innervates the muscles of the posterior compartment that plantar flexes and supplies the skin on the heel and plantar aspect of the foot. The lateral plantar nerve innervates muscles and skin of the lateral plantar aspect of the foot. The sural nerve supplies the skin on the posterolateral aspect of the leg and the lateral aspect of the foot and the little toe.
A patient experiences weakness in dorsiflexing and inverting the foot. Which of the following muscles is damaged?
(A) Peroneus longus
(B) Peroneus brevis
(C) Tibialis anterior
(D) Extensor digitorum longus
(E) Peroneus tertius
The Answer is C. The tibialis anterior can dorsiflex and invert the foot. The peroneus longus and brevis muscles can plantar flex and evert the foot, the peroneus tertius can dorsiflex and evert the foot, and the extensor digitorum longus can dorsiflex the foot and extend the toes.
A 51-year-old woman traveling through British Columbia can see the beautiful blue sky with white clouds but is unable to focus on her face in the mirror. Her lack of accommodation results from paralysis of which of the following muscles?
(A) Tarsal muscle
(B) Sphincter pupillae
(C) Dilator pupillae
(D) Ciliary muscles
(E) Orbitalis muscles
The answer is D. Near focus (accomodation) occurs with contraction of the ciliary muscles and is mediated by parasympathetic fibers running within the oculomotor nerve. The levator palpebrae superioris inserts on the tarsal smooth muscle plate in the upper eyelid and skin of the upper eyelid and opens the eye by elevating the upper eyelid. The sphincter pupillae and dilator pupillae constrict and dilate the pupil, respectively. The orbitalis muscle is a smooth muscle that bridges the inferior orbital fissure and protrudes the eye.
A patient presents with a thrombosis in the popliteal vein. This thrombosis most likely causes reduction of blood flow in which of the following veins?
(A) Greater saphenous
(B) Lesser saphenous
(C) Femoral
(D) Posterior tibial
(E) Anterior tibial
The Answer is C. The popliteal vein drains blood into the femoral vein; thus, blood flow in the femoral vein is reduced. The great saphenous vein drains into the upper part of the femoral vein. Other veins empty into the popliteal vein.
Which structure has numerous small cavities and lies between the orbit and the nasal cavity?
The answer is D. The ethmoid sinus has numerous small cavities and lies between the orbit and the nasal cavity
A 16-year-old patient has weakness flexing the metacarpophalangeal joint of the ring finger and is unable to adduct the same finger. Which of the following muscles is most likely paralyzed?
(A) Flexor digitorum profundus
(B) Extensor digitorum
(C) Lumbrical
(D) Dorsal interosseous
(E) Palmar interosseous
The answer is E. The dorsal and palmar interosseous and lumbrical muscles can flex the metacarpophalangeal joints and extend the interphalangeal joints. The palmar interosseous muscles adduct the fingers, while the dorsal interosseous muscles abduct the fingers. The flexor digitorum profundus flexes the distal interphalangeal (DIP) joints.
A 35-year-old man walks in with a stab wound to the most medial side of the proximal portion of the cubital fossa. Which of the following structures would most likely be damaged?
(A) Biceps brachii tendon
(B) Radial nerve
(C) Brachial artery
(D) Radial recurrent artery
(E) Median nerve
The answer is E. The contents of the cubital fossa from medial to lateral side are the median nerve, the brachial artery, the biceps brachii tendon, and the radial nerve. Thus, the median nerve is damaged. The radial recurrent artery ascends medial to the radial nerve.
A 42-year-old woman with metastatic breast cancer is known to have tumors in the intervertebral foramina between the fourth and fifth cervical vertebrae and between the fourth and fifth thoracic vertebrae. Which of the following spinal nerves may be damaged?
(A) Fourth cervical and fourth thoracic nerves
(B) Fifth cervical and fifth thoracic nerves
(C) Fourth cervical and fifth thoracic nerves
(D) Fifth cervical and fourth thoracic nerves
(E) Third cervical and fourth thoracic nerves
The Answer is D. All cervical spinal nerves exit through the intervertebral foramina above the corresponding vertebrae, except the eighth cervical nerves, which run inferior to the seventh cervical vertebra. All other spinal nerves exit the intervertebral foramina below the corresponding vertebrae. Therefore, the fifth cervical nerve passes between the fourth and fifth cervical vertebrae, and the fourth thoracic nerve runs between the fourth and fifth thoracic vertebrae.
A man is unable to hold typing paper between his index and middle fingers. Which of the following nerves was likely injured?
(A) Radial nerve
(B) Median nerve
(C) Ulnar nerve
(D) Musculocutaneous nerve
(E) Axillary nerve
The answer is C. To hold a typing paper, the index finger is adducted by the palmar interosseous muscle, and the middle finger is abducted by the dorsal interosseous muscle. Both muscles are innervated by the ulnar nerve.
A 58-year-old woman comes to the hospital and complains of progressive loss of voice, numbness, loss of taste on the back part of her tongue, and difficulty in shrugging her shoulders. Her MRI scan reveals a dural meningioma that compresses the nerves leaving the skull. These nerves leave the skull through which of the following openings?
(A) Foramen spinosum
(B) Foramen rotundum
(C) Internal auditory meatus
(D) Jugular foramen
(E) Foramen lacerum
The answer is D. A loss of voice is due to an injury to the recurrent laryngeal nerve of the vagus nerve; numbness and loss of taste on the posterior part of the tongue are due to a lesion of the glossopharyngeal nerve; an inability to shrug the shoulder is due to damage of the accessory nerve. These three CNs exit the skull through the jugular foramen. The foramen spinosum transmits the middle meningeal artery. The foramen rotundum transmits the maxillary division of the trigeminal nerve. The internal auditory meatus transmits the facial and vestibulocochlear nerves. The foramen lacerum transmits nothing, but its upper part is traversed by the internal carotid artery with sympathetic nerve plexus.
A 44-year-old man with “crocodile tears syndrome” has spontaneous lacrimation during eating because of misdirection of regenerating autonomic nerve fibers. Which of the following nerves has been injured?
(A) Facial nerve proximal to the geniculate ganglion
(B) Auriculotemporal nerve
(C) Chorda tympani in the infratemporal fossa
(D) Facial nerve at the stylomastoid foramen
(E) Lacrimal nerve
The answer is A. “Crocodile tears syndrome” (lacrimation during eating) is caused by a lesion of the facial nerve proximal to the geniculate ganglion resulting from misdirection of regenerating parasympathetic fibers, which formerly innervated the salivary glands, to the lacrimal glands. An injury to the auriculotemporal nerve may result in Frey syndrome (sweating while eating), which results from misdirection of regenerating parasympathetic and sympathetic fibers. The chorda tympani carries preganglionic parasympathetic fibers to the submandibular ganglion and taste fibers to the anterior two-thirds of the tongue. The facial nerve innervates the muscles of facial expression. The terminal part of the lacrimal nerve contains postganglionic parasympathetic fibers for lacrimation
A 35-year-old man has difficulty in dorsiflexing the foot. Which of the following muscles is most likely damaged?
(A) Tibialis posterior
(B) Flexor digitorum longus
(C) Tibialis anterior
(D) Peroneus longus
(E) Peroneus brevis
The Answer is C. The tibialis anterior muscle can dorsiflex the foot, whereas all other muscles are able to plantar flex the foot.
A 37-year-old man is brought to the emergency department with a crushed second cervical vertebra (axis) that he suffered after a stack of pallets fell on him at work. Which of the following structures would be intact after the accident?
(A) Alar ligament
(B) Apical ligament
(C) Semispinalis cervicis muscle
(D) Rectus capitis posterior minor
(E) Obliquus capitis inferior
The Answer is D. The rectus capitis posterior minor arises from the posterior tubercle of the atlas and inserts on the occipital bone below the inferior nuchal line. The alar ligament extends from the apex of the dens to the medial side of the occipital bone. The apical ligament extends from the dens of the axis to the anterior aspect of the foramen magnum of the occipital bone. The semispinalis cervicis arises from the transverse processes and inserts on the spinous processes. The obliquus capitis inferior originates from the spine of the axis and inserts on the transverse process of the atlas.
