9] Synovial joints allow free movement between their bony
elements. They are classifi ed into multiple subtypes according to the shape of the articulating surfaces and/or the degree of movement allowed. Which of the following synovial joint types permits multiaxial movement?
(A) Pivot
(B) Ball and socket
(C) Condyloid
(D) Saddle
(E) Hinge

Multiaxial movement occurs
through several (more than two) axes or planes. In ball and socket joints, the rounded head of on bone moves in the concave socket of the other bone, such as the hip and shoulder (glenohumeral) joints. These highly mobile joints permit fl exion-extension,abduction-adduction, medial and lateral rotation,
and other more subtle motions. Choice A (Pivot) is incorrect.
In pivot joints (e.g., the median atlanto-axial joint between the
atlas [C1] and the dens of the axis [C2]; the proximal radioulnar
joint between the head of the radius and the proximal end of
the ulna), a rounded process of one bone fi ts into a relatively
shallow socket of the other bone and is held in place by a strong
ligament. Pivot joints allow only rotation about a single axis,
and these movements are uniaxial or single planar. Choice C
(Condyloid) is incorrect. In condyloid joints, the rounded (con-
dylar) end of one bone moves in the shallow concave end of the other bone, such as the metacarpophalangeal joints. Move-
ment is biaxial (through two planes); however, one movement
typically is dominant. Some authors make a case that condyloid
joints may be multiaxial, depending on the degree of movement
argued for in the third plane. Choice D (Saddle) is incorrect. In
saddle joints, the ends of the articulating bones are both con-
cave and form a saddle-like junction. The movement here is
biaxial (through two planes). The carpometacarpal joint located
at the base of the thumb is a prime example. Choice E (Hinge)
is incorrect. In hinge joints, the rounded end of one bone fi ts
into the concave end of the other. The lateral sides of the joint
are reinforced with strong collateral ligaments so that move-
ment is essentially limited to a hinge-like, uniaxial plane. The
humeroulnar (elbow) joint is a hinge joint.

10)A man exhibits anhydrosis (lack of sweating) and erythema (fl ushing) on his chest due to loss of sympathetic innervation. A thorough neurological analysis reveals dysfunction of presynaptic (preganglionic) sympathetic nerve cell bodies. Which of the following sites is most likely damaged in this patient?

Presynaptic sympathetic neurons originate in the pronounced lateral gray horn of the spinal cord, from spinal segments T1-L2 (or L3). Thus, the sympathetic division is described as having a thoracolumbar outfl ow. It is the sympathetic nerve fi bers that are damaged in this patient, leading to the anhydrosis and erythema. Choice A (Brainstem) is incorrect. Nuclei-housing presynaptic parasympathetic neurons are associated with four cranial nerve outfl ow tracts in the brainstem: Oculomotor nerve (CN III); Facial nerve (CN VII); Glossopharyngeal nerve (CN IX); Vagus nerve (CN X). Because parasympathetic fi bers emerge from both cranial and sacral levels of the central nervous system, this division is described as having a craniosacral outfl ow. Choice C (Sympathetic chain ganglia) is incorrect. The sympathetic chain ganglia, strung along the lateral sides of the vertebral column, contain the cell bodies of postsynaptic sympathetic neurons. These neurons project axons to the head and neck, body wall and limbs, and thoracic viscera. Choice D (Prevertebral ganglia) is incorrect. Prevertebral (preaortic) ganglia are located along the anterior aspect of the vertebral column and house mainly the cell bodies of postsynaptic sympathetic neurons. These cells project their axons to the abdominopelvic viscera and the external genitalia. Choice E (Dorsal root ganglia) is incorrect. Dorsal root (spinal) ganglia, located on each dorsal root of a spinal nerve, contain the cell bodies of general sensory (general somatic afferent; GSA) and visceral sensory (general visceral afferent; GVA) neurons. The axonal processes of these pseudounipolar cells originate as sensory receptors in the periphery and project to the dorsal grey horn in the spinal cord.

11) A 20-year-old woman is surprised to discover that she is pregnant. Following a review of her menstrual history and sexual activity, her physician determines that she is in the 4th week of pregnancy. Which of the following best describes the condition of the embryo at this time?
(A) Gastrulation is complete, resulting in two germ layers
(B) The embryo is entering a period of relative resistance to teratogenic substances
(C) Neurulation is nearly complete (D) Somites have not yet formed
(E) The trophoblast is present, but the syncytiotrophoblast has not yet formed

11)Neurulation (the process of formation of the neural tube) begins late in week 3 with formation of the neural groove and neural folds. However, most of the process, including formation and completion of the neural tube, occurs during week 4. Additional major events during this week include much of somite differentiation, the appearance of the pharyngeal (branchial) apparatus, and the appearance of the upper limb bud. Choice A (Gastrulation is complete, resulting in two germ layers) is incorrect. Gastrulation is the process of formation of the trilaminar germ disc, that is, establishing the three germ layers: ectoderm, endoderm, and mesoderm. Gastrulation is the defi ning characteristic of week 3 of development. Remember “threes”: three germ layers in week 3. Choice B (The embryo is entering a period of relative resistance to teratogenic substances) is incorrect. Weeks 3 to 8 constitute the embryonic period of development, which is the period of organogenesis during which the three germ layers form all tissues and organs. By the end of week 8, the main organ systems are formed and the major external body features are established. This is also regarded as the sensitive period of development because the organ primordia are very sensitive to teratogenic agents. As a result, most gross structural organ defects are induced during this time. Choice D (Somites have not yet formed) is incorrect. Somite formation is normally well underway during the 4th week. Segmentation of the paraxial mesoderm into somitomeres and somites begins late in week 3, with 4 to 7 pairs of somites formed at the cranial end of the embryo at day 21. New somites are added in a craniocaudal sequence at a rate of about 3 pairs per day. There are typically 26 to 29 pairs by the end of week 4, increasing to 42 to 44 pairs at the end of week 5. Because somites appear at a very specifi c rate, their number can be used to determine the age of the embryo with great accuracy during weeks 3 to 5. Choice E (The trophoblast is present, but the syncytiotrophoblast has not yet formed) is incorrect. Differentiation of the trophoblast (the outer cell mass of the blastocyst) into cytotrophoblast and syncytiotrophoblast areas occurs early in week 2. These layers form the fetal component of the placenta and thus are critical to full implantation. At the same time, the embryoblast (the inner cell mass of the blastocyst) differentiates into the bilaminar germ disc, consisting of the epiblast and hypoblast.

12) A child is born at home without diffi culty. Two weeks later, the mother takes the infant to her doctor, reporting that he “turns blue” when he cries. Physical examination reveals the infant is cyanotic and has a distinct systolic heart murmur. The physician suspects the baby has a tetralogy of Fallot (TOF). Which of the following conditions is a component of this syndrome?

An abnormally narrowed right ventricular outfl ow tract (pulmonary infundibular stenosis) is one of the four components of TOF. This syndrome is the most common malformation complex resulting from unequal division of the conus cordis and truncus arteriosus by the spiraling conotruncal septum. This septum contributes signifi cantly to the formation of the ventricular outfl ow tracts and the proximal parts of the aorta and pulmonary trunk. Anterior displacement of the developing conotruncal septum results in a narrow right ventricular outfl ow (pulmonary infundibular stenosis), plus an overriding aorta, ventricular septal defect (VSD), and hypertrophied right ventricle. The four classic characteristics of TOF are pictured in the given fi gure. Children with TOF are typically cyanotic due to the mixing of right and left side blood through the VSD and the overriding aorta. Also, the systolic heart murmur is typical due to the VSD. Choice A (Transposition of the great vessels) is incorrect. Failure of the conotruncal septum to follow its normal spiral course results in transposition of the great vessels. When the septum runs directly downward through the conotruncal region instead of spiraling, the aorta originates from the right ventricle and the pulmonary trunk arises from the left ventricle. Choice B (Hypertrophy of the left ventricle) is incorrect. In TOF, the combination of backpressure from the infundibular stenosis and systemic pressure needs from the overriding aorta and VSD results in hypertrophy of the right ventricle. Choice C (Interatrial septal defect) is incorrect. The conotruncal septum contributes to the formation of the upper (membranous) part of the interventricular septum. Thus, malformation of the conus septum commonly results in a membranous VSD, not an atrial septal defect. Choice E (Aortic valvular atresia) is incorrect. In this condition, the valvular orifi ce into the aorta is absent, and the aorta and left side chambers are underdeveloped. In TOF, the conotruncal septum is displaced, resulting in an open, overriding aorta

13)A young boy who was driving motorcycle at a high speed collided with a tree and was thrown on his right shoulder. Though there was no fracture, his right arm was medially rotated and forearm pronated. The following facts concerning this patient are correct, EXCEPT:

The median nerve also called the 'eye of the hand,' is a mixed nerve with a role of primary importance in the functionality of the hand. It innervates the group of flexor-pronator muscles in the forearm and most of the musculature present in the radial portion of the hand, controlling abduction of the thumb, flexion of the hand at the wrist, flexion of the digital phalanx of the fingers. Again the nerve allows the sensory innervation to the flying face of the thumb, index, middle and radial side of the ring finger and the entire palmar region of the radial half of the hand. It also provides sensitivity to the dorsal skin of the last two phalanges of the index and middle fingers.

The nerve forms in the cervical area of the spinal cord from the medial and lateral cord of the brachial plexus. These cords form from the ventral primary rami of cervical nerve roots five to eight, as well as, the first thoracic spinal segment. The median nerve descends medially to the brachial artery at the level of the humerus and enters the forearm between the two heads of pronator teres. The nerve is very superficial in the cubital fossa and lies deep to bicipital aponeurosis. In the forearm, the median nerve lies deep to the flexor digitorum superficialis and superficial to flexor digitorum profundus. It then enters the palm under the flexor retinaculum lateral to the tendon of flexor digitorum superficialis and posterior to the tendon of palmaris longus. Pathology and injury to the median nerve can occur anywhere along the length of the median nerve.

Of note, in the arm, there are no muscles innervated by the median nerve. Although a branch to pronator teres is innervated proximal to the elbow joint, there are a few vascular branches of the median nerve that supply to the brachial artery and articular branches of the median nerve innervates the elbow joint. In the forearm, the median nerve innervates the flexor digitorum superficialis, pronator teres, the medial half of the pronator quadratus, the palmaris longus, flexor carpi ulnaris, and flexor carpi radialis. Furthermore, in the hand, the flexor pollicis longus and flexor digitorum profundus are innervated by the anterior interossei branch of the median nerve. Articular branches of the median nerve feed the carpal joints, distal radioulnar, and radiocarpal joint. Multiple communicating branches of the median nerve connect to the ulnar nerve. The median nerve innervates the muscles of the thenar compartments of the palm, flexor pollicis longus, abductor pollicis brevis, opponens pollicis, and adductor pollicis. Also, the palmar cutaneous branch of the median nerve innervates the skin over the thenar eminences and lateral two and a half fingers on the palmar aspect of the hand and the skin over the two and a half fingers over the dorsum of the hand.

The median nerve can be affected by acute traumatic, chronic micro traumatic, and compressive lesions. The nerve can also become damaged during multiple-cause degenerative processes and neuropathies. The different types of lesions can affect the median nerve at various levels along its long path from the brachial plexus and axilla to the hand. Neuropathies mainly concern the distal territory. Peripherally, the median nerve can become compressed under the fascial sheath of the flexor retinaculum, which often causes burning pain, numbness, and tingling (neuropathic pain). This condition is known as entrapment syndrome or carpal tunnel syndrome. The carpal tunnel syndrome pain is explainable as a needle and pin sensation, along with the distribution of the median nerve. The condition is idiopathic and is also associated with hypothyroidism, pregnancy, and diabetes. Decreased sensation over a patient's thenar eminence is an indication of a medial nerve injury that is proximal to the carpal tunnel. The sensation of the thenar eminence receives its nerve supply by a branch of the median nerve, which is proximal to the carpal tunnel, the palmar cutaneous branch of the median nerve.

Clinically, symptoms can be intermittent with flares and remissions.

14) An 18-year-old boy is brought to the ER after suffering a gunshot wound to his back. Radiographic imaging reveals extensive damage to the neural arches of the L1 and L2 vertebrae, with bone and bullet fragments lodged in the vertebral canal at these levels. Comprehensive neurologic examination indicates destruction of the sacral segments of the spinal cord. Which of the following functional outcomes is most likely present?

Destruction of the sacral spinal cord will eliminate parasympathetic outfl ow to the hindgut, pelvic organs, and perineum as well as somatic innervation to much of the pelvis and lower limbs. Because it stimulates gut motility and tone, loss of parasympathetic input will result in relaxation and inactivity of the teniae coli in the descending colon. Choice A (Reduced sweat gland secretion in the abdominal wall) is incorrect. Sweat gland secretion is controlled by the sympathetic system, without parasympathetic balance. Sympathetic outfl ow is from the thoracolumbar spinal cord (T1-L2), and it would not be affected by loss of the sacral spinal cord segments. Choice B (Decreased motility in the duodenum) is incorrect. Decreased gut motility may be the result of loss of parasympathetic input. However, the duodenum is innervated by the vagus nerves, not the sacral spinal cord. Choice C (Increased motility in the ileum) is incorrect. Increased gut motility may result from the interruption of sympathetic input. However, the ileum receives its sympathetic input from the thoracolumbar spinal cord (T1-L2/3), not the sacral spinal cord. Choice D (Paralysis of the psoas major muscle) is incorrect. The psoas major is a large muscle in the posterior abdominal wall. It is a skeletal muscle supplied by somatic motor fi bers via spinal nerves L2-3. Thus, the psoas major is not affected by loss of the sacral spinal cord segments.

15) A 68-year-old man was choking on a piece of steak at a family restaurant. Despite attempts to dislodge the food via abdominal thrusts (or the Heimlich maneuver), his upper airway remained blocked. An emergency medical technician (EMT), eating at the scene, performed an emergency tracheotomy to enable the man to breathe. Which subcutaneous structure was most likely cut during this procedure?