Hand Practice Quiz

The extensor expansion of the ring finger receives which tendons?

Dorsal interosseous Extensor digitorum Lumbrical Palmar interosseous ---------------- The tendons from the extensor digitorum muscles flatten to form extensor expansions on the distal ends of the metacarpals and along the phalanges. The dorsal and palmar interosseus muscles and the lumbricals are inserting into these extensor expansions. Extensor carpi ulnaris inserts on the medial side of the base of the 5th metacarpal--it is not inserting near the extensor expansions.

What sesamoid bone develops in the tendon of flexor carpi ulnaris and is therefore not a part of the wrist joint?

Pisiform ------------ The pisiform is a sesamoid bone in the tendon of the flexor carpi ulnaris muscle. It is in the proximal row of carpal bones. It bears the forces generated by the tendon as the tendon rides across triquetrum, especially during wrist extension. Capitate is the largest carpal bone. It is in the distal row of carpal bones, and it transmits forces generated in the hand to lunate and then to the radius. Lunate is a carpal bone in the proximal row which articulates with capitate. Scaphoid is the most lateral carpal bone in the proximal row. It is found in the floor of the anatomical snuff box and it is the most frequently fractured carpal bone.

A person carrying a soft drink in their right hand slipped on some ice and the bottle broke in their hand. A shard (jagged piece) of glass entered the hand and severed all of the tissue from the skin down to the metacarpal bone. The cut extended on the lateral side of the index finger, following the proximal transverse crease, clear to the proximal portion of the head of the second metacarpal bone. It did not extend over the third metacarpal. The clinical manifestations were as follows: 1. The subject could not flex any part of the index finger 2. The subject had trouble abducting and adducting the index finger 3. The subject had total anesthesia on the palmar side of the index finger and the dorsal side of the distal part of the same digit 4. There was considerable bleeding from severed vessels Repair proceeded and required six hours of surgery. Which nerve was most likely cut?

Common palmar digital branches of the median nerve ---------------- Since the patient has total anesthesia on the palmar side of the index finger, you should know that there has been an injury to a superficial branch of the median nerve, and most likely to the radial two common palmar digital branches of median. Remember, the median nerve innervates the radial side of the palm, including the radial 3.5 fingers. So, the only answer that makes sense is common digital branches of the median nerve. The deep branch of the ulnar nerve travels deep in the hand to innervate the intrinsic muscles of the hand. An injury to this nerve would cause a greater motor deficit in the hand. Dorsal digital branches of the radial nerve innervate the radial 3.5 fingers on the dorsum of the hand, but not on the palmar side. The motor branch of the median nerve innervates the thenar compartment. If this nerve was injured, the most important symptom would be that the patient would no longer be able to oppose her thumb. Finally, the proper digital branches of the ulnar nerve are found on the dorsal and palmar side of the 1.5 fingers closest to the ulnar side of the hand, which is far from the injury.

A patient sustained multiple deep lacerations on the palm of his hand and anterior surface of his wrist. During examination, the physician put a piece of paper between adjacent surfaces of the patient's index and middle fingers and found him unable to squeeze them together with sufficient force to hold the paper. The most specific nerve branch to the muscles being tested is the:

Deep branch of the ulnar nerve ------------------- The deep branch of the ulnar nerve is the specific branch of the ulnar nerve that innervates the intrinsic muscles of the hand, with the exception of the thenar compartment and the radial two lumbrical muscles. This includes the interossei, which abduct and adduct the fingers. The median nerve innervates most of the muscles in the anterior compartment of the forearm, with the exception of half of flexor digitorum profundus and flexor carpi ulnaris. Both of these muscles are innervated by the ulnar nerve. The recurrent motor branch of the median nerve innervates the thenar compartment of the hand, including abductor pollicis brevis, flexor pollicis brevis, and opponens pollicis. Finally, the superficial branch of the ulnar nerve provides sensory innervation to the skin on the medial side of the wrist and hand and the medial 1.5 digits on the palmar side of the hand.

The fourth dorsal interosseous muscle is innervated by the:

Deep branch of the ulnar nerve ------------------------ The deep branch of the ulnar nerve innervates the intrinsic muscles of the hand (with the exception of the thenar compartment). This includes the dorsal interosseous muscles, the palmar interosseous muscles, the two lumbrical muscles on the medial side of the hand, and the muscles to the 5th digit (digiti minimi). The dorsal branch of the ulnar nerve innervates the skin of the dorsal surface of the medial 1.5 digits and the skin of the medial side of the back of the hand. The recurrent motor branch of the median nerve innervates the thenar compartment. The superficial branch of the radial nerve provides sensory innervation to the skin on the radial side of the dorsum of the hand, including the radial 3.5 digits. Finally, the superficial branch of the ulnar nerve innervates the skin of the palmar surface of the medial 1.5 digits as well as the skin of the medial side of the front of the hand.

What arterial vessel accompanies the deep branch of the ulnar nerve across the palm?

Deep palmar arterial arch -------------------- The deep palmar arterial arch is made by the radial artery and the deep branch of the ulnar artery. It runs deep in the hand, along with the deep ulnar nerve which innervates the intrinsic muscles of the hand. Although the radial artery contributes to the deep palmar arterial arch, it does not run with the deep branch of the ulnar nerve. Radialis indicis is a branch of the radial artery that runs up the radial side of the index finger, similar to a proper digital artery. The superficial palmar arterial arch is made of the ulnar artery and a superficial branch of the radial artery. Because it is located close to the surface of the hand, it is not related to deeper structures like the deep branch of the ulnar nerve.

After suffering a cut deep to the hypothenar eminence, the patient is unable to hold a sheet of paper between the second and third digits. The nerve most likely injured was the:

Deep ulnar nerve -------------------- To hold the piece of paper between the second and third digits, this patient needs to abduct the middle finger (pull it away from the midline) and adduct the second finger (pull it towards the midline). So, the patient wants to use the palmar interosseous muscles to adduct the second finger and the dorsal interosseous muscles to abduct the third finger. Both of these sets of muscles are innervated by the deep ulnar nerve, so that must be the nerve that was injured. The deep radial nerve is a branch of the radial nerve to innervates the extensor compartment of the arm. The recurrent branch of the median nerve innervates the thenar compartment of the hand; the superficial radial nerve provides cutaneous innervation to the lateral 3.5 fingers on the dorsal side of the hand. Remember--the deep ulnar nerve innervates all the muscles in the hand, except for the thenar compartment and the first two lumbricals. Those muscles are innervated by the median nerve!

While watching her boyfriend split wood, a teenager was struck on the back of her carpals by a sharp- edged flying wedge. Her extensor digitorum tendons were exposed, though not severed, indicating that the surrounding synovial sheath had been opened. What other muscle has its tendon surrounded by the same synovial sheath?

Extensor indicis muscle ------------ Extensor indicis is a deep forearm extensor that extends the index finger only. Its tendon joins the tendon of the extensor digitorum which goes to the second digit, and both tendons insert into the extensor expansion. Since these tendons insert together, it would make sense that they would be contained in a common synovial sheath. All of the other tendons listed have their own synovial sheaths. To visualize these concepts, see Netter 453.

In order to check the pulse of a child whose forearm is in a cast, the pediatrician presses her finger into the depth of the "anatomical snuffbox". The tendon lying immediately medial (ulnar) to the physician's finger belongs to what muscle?

Extensor pollicis longus muscle ---------------- The anatomical snuff box is bounded on the ulnar side by the tendon of extensor pollicis longus. It is bounded radially by the tendons of abductor pollicis longus and extensor pollicis brevis. The radial artery lies in the floor of the snuff box, and scaphoid can be felt in the floor of the anatomical snuff box. Extensor carpi radialis longus and brevis attach their tendons to the base of the second and third metacarpals, respectively. Brachioradialis inserts its tendon on the lateral side of the base of the styloid process of the radius.

What movement of the thumb would be most affected by lesion of the median nerve in the cubital fossa:

Flexion ----------- If the median nerve was injured in the cubital fossa, all the muscles innervated by the median nerve which are found distal to the cubital fossa would be injured. The thenar compartment of the hand and the flexor muscles of the forearm would be denervated (with the exception of flexor carpi ulnaris and the ulnar half of flexor digitorum profundus--both of these muscles are innervated by the ulnar nerve). This means that none of the muscles which allow for flexion of the thumb would be intact. Flexor pollicis brevis is innervated by the recurrent branch of the median nerve and flexor pollicis longus is innervated by the median nerve. Both of these muscles would be denervated. Abduction is performed by abductor pollicis longus (innervated by the radial nerve) and abductor pollicis brevis (innervated by the median nerve). So, abduction might be weakened, but it would not be completely lost following damage to the median nerve. Adduction is performed by adductor pollicis, which is a muscle in the medial compartment of the hand, innervated by the deep ulnar nerve. Extending the thumb is accomplished by extensor pollicis longus and brevis, which are both innervated by the deep radial nerve.

A person carrying a soft drink in their right hand slipped on some ice and the bottle broke in their hand. A shard (jagged piece) of glass entered the hand and severed all of the tissue from the skin down to the metacarpal bone. The cut extended on the lateral side of the index finger, following the proximal transverse crease, clear to the proximal portion of the head of the second metacarpal bone. It did not extend over the third metacarpal. The clinical manifestations were as follows: 1. The subject could not flex any part of the index finger 2. The subject had trouble abducting and adducting the index finger 3. The subject had total anesthesia on the palmar side of the index finger and the dorsal side of the distal part of the same digit 4. There was considerable bleeding from severed vessels Repair proceeded and required six hours of surgery. Which muscle tendons were involved?

Flexor digitorum profundus muscle Flexor digitorum superficialis muscle First dorsal interosseous muscle First lumbrical muscle ------------------------ The palmar interosseous muscles adduct the 2nd, 4th, and 5th fingers to the middle finger. So, the second palmar interosseous muscle is found on the lateral side of the 4th finger, far away from the site of injury. Since the subject cannot flex the index finger, you can assume that the tendons of flexor digitorum profundus and superficialis were cut. The first dorsal interosseous muscle is located on the lateral side of the index finger; given its location (and that the subject has trouble abducting the index finger), it seems that this tendon was damaged. The first lumbrical muscle is also on the lateral side of the index finger--it was also injured by the cut.

What muscle tendon is enclosed within its own synovial sheath in the carpal canal?

Flexor pollicis longus muscle ---------------- Flexor pollicis longus is enclosed in its own synovial sheath in the carpal canal, called the radial bursa. The tendons from flexor digitorum profundus and flexor digitorum superficialis are all contained in a common synovial sheath, called the ulnar bursa. The ulnar bursa and radial bursa are both in the carpal tunnel, along with the median nerve. (Are you getting the idea that you really need to know about the carpal tunnel?!) Flexor carpi ulnaris and palmaris longus are not located in the carpal tunnel.

The signs and symptoms of carpal tunnel syndrome may vary among patients, but they always result from compression of what structure in the carpal canal?

Median nerve --------------- Carpal tunnel syndrome is caused by a compression of the median nerve within the carpal tunnel. The carpal tunnel is a canal on the anterior side of the wrist. It is made of the carpal bones which are covered by the flexor retinaculum. It contains the tendon of flexor pollicis longus, the tendons of flexor digitorum superficialis and profundus, and the median nerve. If the sheath over the common flexor tendons, the ulnar bursa, becomes inflamed, this can compress the median nerve in the canal, leading to pain and weakness in the hand. None of the other structures mentioned in the question are contained in the carpal tunnel, so they would not be compressed in that space.

The point of insertion of the flexor digitorum superficialis tendon to the index finger is on the:

Middle phalanx --------------- The flexor digitorum superficialis tendon inserts on the middle phalanx of fingers 2-5; the flexor digitorum profundus tendon inserts on the base of the distal phalanx of fingers 2-5. Both muscles flex the metacarpophalangeal and proximal interphalangeal joints, but flexor digitorum profundus is the only muscle that flexes the distal interphalangeal joints.

In carpal tunnel syndrome, compression of the median nerve in the carpal tunnel affects which hand muscle?

Opponens pollicis Abductor pollicis brevis Flexor pollicis brevis ---------------- The recurrent branch of the median nerve innervates the thenar compartment, including abductor pollicis brevis, flexor pollicis brevis, and opponens pollicis. If the median nerve was damaged, any of these muscles might be denervated. Adductor pollicis, the palmar interosseus muscles, and opponens digiti minimi are all innervated by the deep branch of the ulnar nerve.

In order to evaluate the carpal-metacarpal joint of the thumb, the median nerve must be deadened at the wrist (causing paralysis of the muscles supplied by it distal to the injection) to test the joint. Which movement of the thumb would be most affected by the anesthetic?

Opposition --------------- If the median nerve was deadened at the wrist, a patient would lose the use of the thenar compartment of the hand. Abductor pollicis brevis, flexor pollicis brevis, and opponens pollicis would be paralyzed. Opponens is the only muscle that allows for opposition of the thumb, so a patient would no longer be able to oppose the thumb to the fingers. Although abductor pollicis brevis would be paralyzed, abductor pollicis longus would still be functional and the patient could still abduct the thumb. Adductor pollicis is in the adductor compartment, and it is innervated by the deep branch of the ulnar nerve. This means that adduction would not be affected by deadening the median nerve. Extensor pollicis brevis and longus are innervated by the deep radial nerve, so extension would still be intact. Although flexor pollicis brevis would be denervated, flexor pollicis longus could still flex the thumb. It is a muscle of the forearm which is innervated by the median nerve proximal to the site of the anesthesia.

A girl playing softball cuts the palm of her hand as she scoops up a piece of glass along with the ball. If the only nerve damaged is the recurrent branch of the median nerve, she would lose what movement of the thumb?

Opposition of the thumb ------------ If the recurrent branch of the median nerve was injured, abductor pollicis brevis, flexor pollicis brevis, and opponens pollicis would be denervated. Opponens is the only muscle that allows for opposition of the thumb. So, by denervating opponens, the girl would no longer be able to oppose her thumb. Although abductor pollicis brevis would be denervated, abductor pollicis longus would still be functional, so she could abduct her thumb. Adductor pollicis is in the adductor/interosseous compartment, deep in the center of the hand, and it is innervated by the deep branch of the ulnar nerve. This means that adduction would not be affected by the injury to the recurrent branch of the median nerve. Although flexor pollicis brevis was denervated, this is not the flexor that is responsible for flexion at the distal phalanx. Flexor pollicis longus controls flexion at the distal phalanx, and it is a muscle of the forearm which is innervated by the median nerve.

A person carrying a soft drink in their right hand slipped on some ice and the bottle broke in their hand. A shard (jagged piece) of glass entered the hand and severed all of the tissue from the skin down to the metacarpal bone. The cut extended on the lateral side of the index finger, following the proximal transverse crease, clear to the proximal portion of the head of the second metacarpal bone. It did not extend over the third metacarpal. The clinical manifestations were as follows: 1. The subject could not flex any part of the index finger 2. The subject had trouble abducting and adducting the index finger 3. The subject had total anesthesia on the palmar side of the index finger and the dorsal side of the distal part of the same digit 4. There was considerable bleeding from severed vessels Repair proceeded and required six hours of surgery. The excessive bleeding most likely came from which of the following arteries?

Radialis indicis artery -------------------- The radialis indicis artery is the equivalent of a proper digital artery on the lateral side of the index finger, which is the site of the injury. It is a direct branch of the radial artery. The deep palmar arterial arch is made by the radial artery and the deep branch of the ulnar artery. It is found deep in the hand, so it's not near the area of injury. Princeps pollicis is a branch of the radial artery that provides blood to the thumb; it is similar to a proper digital artery. Since it supplies blood to the thumb, it would not have been cut along the lateral side of the index finger. The radial artery and ulnar artery supply blood to the hand through the deep and superficial palmar arterial arches; they do not extend up to the fingers.

A student is rollerblading on the Diag and while trying to avoid a bicyclist falls heavily on his right wrist. After the fall he notes severe pain in the anatomical snuff box. Radiological studies reveal a fracture of the bone deep to the snuff box called the

Scaphoid bone ---------------- The scaphoid is the bone found at the floor of the anatomical snuff box. It is in the proximal row of carpals and it is frequently fractured. Capitate, hamate and trapezium are three carpal bones located in the distal row of carpals. Capitate is the largest carpal bone; it transmits force from the hand to the lunate and the radius. Hamate has a distinct hook; it is an attachment point for the flexor retinaculum. Trapezium is the carpal bone that articulates with the metacarpal bone of the thumb, forming a saddle joint. Lunate is in the proximal row of carpal bones, located next to scaphoid. It articulates with the capitate.

A patient sustained multiple deep lacerations on the palm of his hand and anterior surface of his wrist. During examination, the physician put a piece of paper between adjacent surfaces of the patient's index and middle fingers and found him unable to squeeze them together with sufficient force to hold the paper. What muscles are being tested?

Second dorsal and first palmar interosseous muscles ------------------ When you are thinking about abducting and adducting digits in the hand, remember that the midline extends through the middle digit. So, this patient is trying to adduct his index finger by pulling it towards the midline and abduct his middle finger by pulling it away from the midline. This means that the patient is using the palmar interosseous muscle (the adductor) on his index finger and the dorsal interosseous muscle (the abductor) on his middle finger. So, the patient has damaged the first palmar interosseous muscle and the second dorsal interosseous muscle. Take a look at Netter 465 for a picture of the dorsal and palmar interosseous muscles and their numbering.

Bleeding from a superficial cut in the middle of the palm of the hand near the proximal transverse crease comes mainly from what vessel?

Superficial palmar arch ------------------- The superficial palmar arch is a superficial arterial arch found on the palm of the hand--it is mostly formed by the ulnar artery, but it is completed by the superficial branch of the radial artery. This arch crosses along the palm of the hand, so a cut in the middle of the palm would be likely to disrupt this vessel. Princeps pollicis is a branch of the radial artery--it supplies blood to the thumb, and is similar in function to a proper digital artery. The radial artery is a major artery supplying the forearm--in the hand, the radial artery is the primary source of blood to the deep palmar arterial arch. Radialis indicis is a branch of the radial artery that supplies blood to the radial side of the index finger. Finally, the ulnar artery is the other major artery of the forearm--it is the artery that supplies the blood to the superficial palmar arch.

Structures within the carpal tunnel include:

Tendon of the flexor digitorum superficialis Tendon of the flexor digitorum profundus (contained in the ulnar bursa) Tendon of the flexor pollicis longus (contained in the radial bursa) Median nerve ---------------- The flexor retinaculum spans between the carpal bones to make the carpal tunnel. The contents of the carpal tunnel are: the tendons of flexor digitorum superficialis and flexor digitorum profundus (all contained in the ulnar bursa); the tendon of flexor pollicis longus (contained in the radial bursa) and the median nerve. So, the radial bursa is the only listed structure that is found in the carpal tunnel. The ulnar nerve is superficial to the flexor retinaculum - it's not in the carpal tunnel. The palmar aponeurosis and superficial palmar arterial arch are found on the superficial surface of the palm of the hand--they are not structures found at the wrist. Adductor pollicis is a muscle in the adductor-interosseous compartment of the hand - it is not found near the wrist.

The main source of blood to the superficial palmar arterial arch is the:

Ulnar artery ------------- The ulnar artery is the main source of blood to the superficial palmar arterial arch; the arch is completed on the radial side by the superficial palmar branch of the radial artery. The radial artery is the main source of blood to the deep palmar arterial arch, which is completed on the ulnar side by the deep branch of the ulnar artery.

A deep puncture wound in the palmar surface of the little finger near the proximal IP joint might introduce infection into which synovial cavity:

Ulnar bursa ----------------- The ulnar bursa is a synovial sheath covering the digital flexor tendons--it covers the flexor tendons as they pass under the flexor retinaculum and terminates near the center of the palm for the second, third, and fourth fingers. However, the portion of the ulnar bursa which is concerned with the fifth finger does not terminate in the middle of the palm--instead, it continues all the way into the insertion of the profundus tendon into the fifth digital phalanx. This means that a superficial cut on the palmar side of the fifth digit can introduce an infection into the ulnar bursa. The radial bursa is the other bursa associated with the flexor tendons--it is a synovial sheath for flexor pollicis longus that extends to the point where this tendon inserts on the distal phalanx of the thumb. A superficial cut on the palmar side of the thumb might introduce an infection into the radial bursa. See Netter Plate 446 to get a good idea of these bursae Flexor carpi ulnaris inserts on the pisiform, hamate, and the fifth metacarpal--so, the bursa associated with this tendon would not be found near the digits. The fibrous digital sheath of the fingers covers the ulnar bursa and the flexor tendons--these sheaths hold the tendons on the fingers. The intercarpal joint space is the space between the carpal bones.