Nerve & Tendon MCQs

The milking test, as seen in the photograph, elicits pain when a tear is present in the medial collateral ligament. Complete rupture is possible but unlikely when there is no history of trauma and the patient is able to throw pain-free for several innings. Subluxation of the ulnar nerve and triceps tendon subluxation present as a painful snapping over the medial aspect of the elbow.

DISCUSSION: The PCBMN originates from the median nerve proper between 3 and 21 cm proximal to the wrist with moderate variation. It virtually always originates from the radial side of the nerve and travels distally with the median nerve, radial to the palmaris longus, and ulnar to the flexor carpi radialis. REFERENCES: Hobbs RA, Magnussen PA, Tonkin MA: Palmar cutaneous branch of the median nerve. J Hand Surg Am 1990;15:38-43. Netter F: The Ciba Collection of Medical Illustrations: The Musculoskeletal System: Part 1, Anatomy, Physiology and Metabolic Disorders. West Caldwell, NJ, Ciba-Geigy, 1991, vol 8, p 52.

The patient’s symptoms and examination findings are consistent with ulnar neuritis/cubital tunnel syndrome, most probably exacerbated by javelin throwing. The first step includes rest and extension splinting. Surgical intervention should only be considered after failure of nonsurgical management.

The MRI scan shows a large mass (lipoma) in the thenar muscles of the palm. The recurrent motor branch of the median nerve innervates the thenar muscles. The anterior interosseous nerve (AIN) in the proximal forearm innervates the flexor pollicis longus, pronator quadratus, and flexor digitorum pollicis to the index and frequently the middle finger. The terminal branch of the AIN innervates only the wrist capsule. The palmar cutaneous branch of the ulnar nerve is a sensory structure to the hypothenar area. There is no commonly described recurrent branch of the ulnar nerve.

DISCUSSION: The injury shown is a flexion-type supracondylar humerus fracture. The most commonly interposed anatomic structure is the ulnar nerve. The brachialis muscle is often interposed in extension-type fractures, as are the median nerve and radial artery.

DISCUSSION: The posterior cord of the brachial plexus terminates into the radial and axillary nerves.  The lateral cord terminates in branches to the musculocutaneous and the lateral root of the median nerve.  The medial cord terminates in branches to the ulnar and medial roots of the median nerve.REFERENCE: Hollinshead WH: Anatomy for Surgeons: The Back and Limbs, ed 3.  Philadelphia, PA, Harper and Row, 1982, pp 228-236.

This high level throwing athlete has a full-thickness injury to the ulnar collateral ligament and is most likely to be able to return to competitive throwing with an ulnar collateral ligament reconstruction. There is no radiographic evidence of a medial epicondyle fracture. The clinical presentation and lack of a posteromedial olecranon osteophyte makes valgus extension overload unlikely, and therefore, makes arthroscopic osteophyte excision a suboptimal choice. Whereas ulnar nerve pathology can coexist with an ulnar collateral ligament injury, isolated ulnar nerve transposition without addressing the ligament injury is not warranted in this patient. Initial nonsurgical management with activity modification and physical therapy is appropriate for partial-thickness injury to the ulnar collateral ligament in a nonthrowing athlete, and in athletes whose sporting activity places them at low risk.

The arrows in the figure show the deep branch of the ulnar nerve (more radial) and the superficial branch of the ulnar nerve within Guyon’s canal. Guyon’s canal is approximately 4 cm long beginning at the proximal extent of the transverse carpal ligament and ends at the aponeurotic arch of the hypothenar muscles. Many structures comprise the boundaries of Guyon’s canal. The floor, for example, consists of the transverse carpal ligament, the pisohamate and pisometacarpal ligaments, and the opponens digiti minimi. Within Guyon’s canal, the ulnar nerve bifurcates into the superficial and deep branches. The ulnar artery is immediately adjacent and radial to the ulnar nerve. The median nerve is visualized within the carpal tunnel, and the palmar cutaneous branch is more radial to Guyon’s canal and volar to the carpal tunnel. The radial and ulnar digital nerves to the little finger are branches off of the superficial branch of the ulnar nerve distal to its emergence from Guyon’s canal. The ulnar artery is the round structure located radial to the branches of the ulnar nerve within Guyon’s canal. Adjacent to the ulnar artery are two small veins. The dorsal cutaneous branch of the ulnar nerve branches from the ulnar nerve in the distal forearm, well proximal to Guyon’s canal. The common digital artery to the fourth web branches from the superficial palmar arch distal to Guyon’s canal. The hook of the hamate is clearly seen in the figure, orienting the observer to the ulnar side of the wristA 37-year-old patient with type I diabetes mellitus has a flexor tenosynovitis of the thumb flexor tendon sheath following a kitchen knife puncture wound to the volar aspect of the thumb. Left unattended, this infection will likely first spread proximally creating an abscess in which of the following spaces of the palm?Central spaceHypothenar spaceCarpal tunnelPosterior adductor spaceThenar spaceCORRECT ANSWER: 5Flexor tenosynovitis of the thumb flexor tendon sheath can spread proximally and form an abscess within the thenar space of the palm. The flexor pollicis longus tendon does not pass through the central space of the palm or the hypothenar space of the palm. The flexor pollicis longus tendon does pass through the carpal tunnel, but this is not a palmar space. The three palmar spaces include the hypothenar space, the thenar space, and the central space. The posterior adductor space would likely only be involved secondarily after spread from a thenar space infection.New painful paresthesias near the site of the incision after an ulnar nerve transposition is the result of injury to what nerve?Medial antebrachial cutaneousLateral antebrachial cutaneousPosterior antebrachial cutaneousMedial brachial cutaneousDorsal antebrachial cutaneousBranches of the medial antebrachial cutaneous nerve can often be identified during routine ulnar nerve surgery crossing the medial aspect of the elbow. It should be preserved to avoid development of painful paresthesias.A 21-year-old man who was injured in a snowboarding accident 18 months ago now reports wrist pain. An MRI scan is shown in Figure

Swan neck deformity describes a posture of the finger in which the PIP joint is hyperextended and the DIP joint is flexed. Initially this is a dynamic imbalance that occurs when a patient attempts maximal digital extension. This dynamic finger imbalance can progress to a static deformity. There are many etiologies for SND and include injuries resulting in volar plate laxity (e.g. dorsal dislocation of the PIP.), spastic conditions such as stroke & CP, RA, fractures of the middle and proximal phx healed in extension.Question 199 -Examination of a 3-year-old boy who slammed his finger in a door 3 months ago reveals 0 to 40 degrees of proximal interphalangeal joint motion. Radiographs are shown in Figures 47a and 47b. Management should consist ofVolar osteotomyObservation onlyFlexor tenolysisVolar plate arthoplastyA hinged distraction external fixatorSubcondylar fractures of the proximal and middle phalynx occur at the neck of the phalynx, usually as a result of a crush injury, and almost exclusively in the pediatric age group. The distal fragment rotates dorsally and the degree of displacement may be misjudged if a true lateral is not obtained. If malunion occurs there is block to flexion. Subcondylar fossa reconstruction by removal of bone through a palmar approach removes this boney block.

The median nerve passes through the pronator teres and deep to the flexor digitorum superficialis. The ulnar artery passes deep to both.

DISCUSSION: Branches of the medial antebrachial cutaneous nerve can often be identified during routine ulnar nerve surgery crossing the medial aspect of the elbow. It should be preserved to avoid development of painful paresthesias.

The ulnar nerve divides alongside the pisiform, and the deep branch supplies the three hypothenar muscles and crosses the palm with the deep palmar arch to supply the two ulnar lumbricals, all interossei, and finally the adductor pollicis.

The MR images show a lesion consistent with a ganglion cyst located near the hook of the hamate. The ulnar nerve divides into motor and sensory branches just proximal to this lesion. In this case, the ganglion cyst compresses the ulnar nerve motor branch but not the sensory branch, resulting in motor dysfunction but no sensory disturbance. Excision of the ganglion cyst should alleviate his symptoms. Compression of the ulnar nerve proximal to the motor branch take-off (in either the cubital tunnel or proximal Guyon’s canal) would cause both sensory and motor dysfunction. Although chronic nonunion of the hook of the hamate can cause ulnar nerve symptoms, the hook of the hamate appears intact on the MR image. The MR image shows a lesion that is well circumscribed with high intensity on T1 and T2 images, consistent with a benign ganglion cyst, and ganglion cysts are relatively common lesions in this area.

The recurrent motor branch of the median nerve supplies the thenar muscles (abductor pollicis brevis, flexor pollicis brevis, and opponens pollicis) that are primarily responsible for thumb opposition. The nerve can be injured in carpal tunnel release. A branch of the nerve also supplies the first lumbrical. The adductor pollicis and the interossei are supplied by the ulnar nerve.

DISCUSSION: The radial nerve is only 4 mm from the anterolateral portal, while the median nerve is 11 mm away from the anteromedial portal. The ulnar nerve is only at risk on the medial side of the elbow. Anterior and posterior interosseous nerves are more distal within the forearm and are not in danger during portal placement.

DISCUSSION: In the thrower’s elbow, ulnar neuritis is felt to result from both chronic compression and traction on the nerve that occurs during the throwing motion. Occasionally, subluxation of the nerve also can lead to symptoms. If nonsurgical management fails to provide relief, transposition of the nerve to an anterior subcutaneous location is the surgical procedure of choice. The nerve is held in its new position by one or two fascial slings created from the fascia of the common flexor origin. REFERENCES: Schickendantz MS: Diagnosis and treatment of elbow disorders in the overhead athlete. Hand Clin 2002;18:65-75. Eaton RG, Crowe JF, Parkes JC III: Anterior transposition of the ulnar nerve using a non-compressing fasciodermal sling. J Bone Joint Surg Am 1980;62:820-825.

During surgical repair of a distal biceps tendon rupture, regardless of the surgical approach or technique, an understanding of the regional anatomy is important. The tendon passes distally into the antecubital fossa. The antecubital fossa is defined by the brachioradialis radially and the pronator teres ulnarly. A sheath surrounds the biceps tendon as it passes through the antecubital fossa toward its insertion on the radial tuberosity. The lateral antebrachial cutaneous nerve lies superficially in the subcutaneous tissue of the antecubital fossa. The nerve parallels the brachioradialis. While still superficial, the tendon is contiguous with the lacertus fibrosus that becomes confluent medially with the fascia overlying the flexor-pronator mass. The brachial artery lies just beneath the lacertus fibrosus at the level of the elbow flexion crease. The tendon travels just lateral (radial) to the median nerve within the antecubital fossa and passes posterior (deep) to the recurrent radial artery before it attaches to the radial tuberosity. Full forearm supination allows visualization of the tendinous insertion on the radial tuberosity.

The superior ulnar collateral, inferior ulnar collateral, and posterior ulnar recurrent arteries provide consistent vascular supply to the ulnar nerve. This supply is segmental in nature. The inferior ulnar collateral artery provides the only direct vascularization to the nerve and is located in the region just proximal to the cubital tunnel. The segmental nature of the blood supply to the ulnar nerve underscores the importance of its preservation during transposition.

Discussion: In the midforearm, the ulnar nerve travels deep to the flexor carpi ulnaris muscle and ulnar to the ulnar artery as it lies on the flexor digitorum profundus muscle. In this region, the ulnar nerve and artery lie side-by-side, whereas more proximal in the forearm, the ulnar artery originates from the brachial artery in the antecubital fossa, and the ulnar nerve lies within the cubital tunnel.

Hypothenar atrophy is a nonspecific sign that can be seen in ulnar neuropathy, C8 radiculopathy, or even cervical myelopathy; however, the atrophy usually is not unilateral and includes other muscle groups. The Spurling test is an excellent method of eliciting cervical radicular pain but involves hyperextension and ipsilateral rotation of the cervical spine, resulting in nerve root compression by reducing the cross-sectional area of the ipsilateral neuroforamen. Tinel’s sign at the levator scapulae, if present, is indicative of an upper cervical (C3 or C4) radiculopathy. A subluxable ulnar nerve at the cubital tunnel, while often asymptomatic, points toward cubital tunnel syndrome as an etiology for this patient’s pain. The shoulder abduction relief (SAR) sign (relief of upper extremity pain with shoulder abduction) is virtually pathognomic of cervical radiculopathy because this maneuver results in relaxation of a compressed and/or inflamed cervical nerve root. The SAR sign is the converse analog of the straight leg raising sign in the lumbar examination for lumbar radiculopathy, as it relieves tension in the nerve root, thereby relieving symptoms.