Save my name, email, and website in this browser for the next time I comment. Detailed complex concepts explanation through clear and concise discussions. Review your learning with practice review questions. It presents 53 real-life clinical cases that illustrate essential concepts in gross anatomy.
Each case includes an easy-to-understand discussion correlated to key basic science concepts, definitions of key terms, anatomy pearls, and USMLE-style review questions. With this interactive system you'll learn instead of memorize.
Moreover Cmecde. An axillary-type crutch that is too long can compress the pos- terior cord, leading to radial nerve palsy. He presents with his right upper arm at his side due to loss of abduction.
Which of the following muscles are primarily responsible for abduction of the arm at the shoulder? Deltoid and biceps brachii B. Deltoid and supraspinatus C. Deltoid and infraspinatus D. Supraspinatus and infraspinatus E. Coracobrachialis and supraspinatus [1. Which of the following find- ings would you observe in a patient with this injury? Weakness of abduction of the arm at the shoulder B. Weakness of adduction of the arm at the shoulder C. Weakness of extension of the forearm at the elbow D.
Weakness of flexion of the forearm at the elbow E. Weakness of supination of the forearm and hand [1. The physician suspects injury to the lower brachial plexus. Which of the following nerves is most likely to be affected? Axillary B. Musculocutaneous C. Vagus D. Radial E. The deltoid and supraspinatus muscles, which are innervated by the axillary and suprascapular nerves, respectively, are the primary abductors of the arm at the shoulder.
Injury to the musculocutaneous nerve will result in loss or weak- ness of flexion at the elbow due to paralysis of the biceps brachii and brachialis muscles. The C8 and T1 portions of the lower brachial plexus make up the majority of the ulnar nerve. In ulnar nerve palsies, the patent is unable to abduct and adduct the fingers.
Clinically Oriented Anatomy, 5th ed. Netter FH. Atlas of Human Anatomy, 4th ed. Philadelphia, PA : Saunders, plates , Snell RS. Clinical Anatomy by Regions, 8th ed. He used three-point restraints and was driving a sedan.
The patient has multiple injuries including a displaced frac- ture of the left humerus. He complains of an inability to open his left hand and loss of sensation to a portion of his left hand.
He has motor and sensory losses to his left hand. Humeral fractures involving the midshaft region are of particular concern. There is loss of innervation of the posterior extensor muscles in the forearm, resulting in wrist drop and an inability to extend the digits at the metacarpophalangeal joints. The sensory loss on the dorsum of the hand and digits reflects the distal cutaneous distri- bution of the radial nerve.
The triceps muscle extensor of the elbow is typi- cally spared; however, the patient usually will not attempt to move the limb due to pain from the fracture. The deep brachial artery has the same path as the radial nerve in the radial groove and has a similar risk for injury. Be able to describe the origin, course, muscles innervated, and distal cutaneous regions supplied by the radial nerve.
Be able to describe the arterial blood supply to the upper limb. Be able to describe the origin, course, muscles innervated, and distal cutaneous regions supplied by the five major terminal branches of the brachial plexus Cases 1, 2, and 4.
Definitions Fracture: A break in the normal integrity of a bone or cartilage. Blunt trauma: Injury due to a crushing force as opposed to a sharp pene- trating force. It gives off multiple muscular branches to the triceps muscle in the posterior compartment. The nerve then pierces the lateral intermuscular septum to return to the anterior compartment of the arm and descends to the level of the lateral epicondyle of the humerus; at this level, it lies deep to the brachio- radialis muscle, where it divides into its two terminal branches.
The deep branch of the radial nerve is entirely motor to the muscles of the posterior compartment of the forearm. The other terminal branch, the superficial branch of the radial nerve, is sensory to the dorsum of the hand and to the dorsum of the thumb, index finger, and the radial side of the middle finger.
The radial nerve also has cutaneous sensory branches to the posterior and lateral arm and to the posterior forearm. The blood supply to the upper limb is derived from the brachial artery, a direct continuation of the axillary artery. It begins at the lower border of the teres major muscle and accompanies the median nerve on the medial aspect of the humerus, where its pulsations can be palpated or the artery occluded to control hemorrhage.
In its descent toward the elbow, it gives off the deep brachial artery, which supplies the posterior compartment of the arm, and passes around the radial groove of the humerus with the radial nerve. It also has ulnar collateral branches to the elbow joint. The brachial artery shifts anteriorly as it enters the forearm, lying just medial to the tendon of the biceps brachii muscle in the cubital fossa.
At about the level of the neck of the radius, it divides into the ulnar and radial arteries, the main arteries of the forearm and hand. Near their origin, each sends recurrent arterial branches to supply the elbow joint.
The radial artery supplies the lateral aspects of the forearm and at the wrist passes dorsally deep through the anatomical snuff box see Case 3 to become the deep palmar arch. The ulnar artery is the larger branch of the brachial, and it supplies the medial aspect of the forearm. A branch close to its origin, the common interosseous artery, divides into anterior and posterior interosseous arteries.
The latter artery is the main blood supply to the posterior compartment. At the wrist, the ulnar artery enters the hand to form the super- ficial palmar arch. The superficial and deep palmar arches form an arte- rial anastomosis and give rise to arteries to the digits. Also see Case 1. The radial nerve. Which of the following terminal nerves would most likely be affected?
Axillary nerve B. Musculocutaneous nerve C. Median nerve D. Radial nerve E. Ulnar nerve [2. Which of the following muscle tests would you perform to test the integrity of the radial nerve? Flexion of the forearm at the elbow B.
Flexion of the hand at the wrist C. Extension of the hand at the wrist D. Abduction of the index, middle, ring, and little fingers E. Adduction of the index, middle, ring, and little fingers [2. If you are planning to draw the sample from the brachial artery, where should you insert the needle? In the lateral aspect of the arm, between the biceps and triceps brachii muscles B.
Just lateral to the biceps tendon in the cubital fossa C. Just medial to the biceps tendon in the cubital fossa D. Just medial to the tendon of the flexor carpi radialis muscle at the wrist E. Just lateral to the tendon of the flexor carpi ulnaris muscle at the wrist Answers [2. The radial nerve is a direct continuation of the posterior cord and is affected by injuries to the posterior cord.
The radial nerve innervates the muscles of the posterior compart- ment, which contains the extensors of the wrist. The brachial artery lies superficial and just medial to the tendon of the biceps brachii in the cubital fossa. Injury to the radial nerve results in wrist drop. Philadelphia, PA: Saunders, plates , —8. Two days later, he phoned his anatomist father and related that his right wrist was painful.
Later that day, he visited his father who noted that the wrist was slightly swollen, tender, but without deformity. His father told him a radiograph is needed. The wrist is slightly swollen, tender, but not deformed. However, deep palpation of the anatomical snuff box elicits extreme tenderness. His hand, with the palm down and probably deviated to the side of the radius, took the brunt of the fall, resulting in significant impact force to the wrist. This results in pain and swelling of the wrist, espe- cially on the radial side, with point tenderness deep in the anatomical snuff box.
This is the common mechanism for a fracture of the scaphoid carpal bone, the most commonly fractured carpal bone. Point tenderness over a bone or bony process is a hallmark of a fracture at that site. Radiologic confirma- tion of a fracture is important. The scaphoid bone has a unique blood supply, and proper reduction and alignment of the segments is necessary to decrease the risk of avascular necrosis.
A fall on an outstretched hand in a way that produces hyperextension of the wrist may result in dislocation of the lunate bone. The lunate is usually displaced anteriorly into the carpal tunnel and may impinge on the median nerve.
The lunate is the most commonly dislocated carpal bone. A fall on an outstretched palm may also result in a transverse frac- ture of the distal radius or a Colles fracture.
A Smith fracture of the radius in the same region of younger individuals is less common. Be able to describe the bones and joints of the wrist. Be able to describe the anatomy of the radius and ulnar as it relates to the transmission of forces in the upper limb and its effect on the fore- arm bones. Be able to describe the boundaries of the anatomical snuff box and its clinical significance.
Fracture: A break in the normal integrity of a bone or cartilage. Avascular necrosis: Death of cells, tissues, or an organ due to insufficient blood supply.
The articulation of the distal radius with the ulna, called the distal radioulnar joint, is the site of movement of the radius anteriorly around the ulna during pronation. The radius and ulna are united by an articular disc or triangular fibrocartilage and associated ligaments, which intervenes between the ulna and carpal bones.
The wrist joint proper is formed between the distal radius, the triangular fibrocartilage, and the proximal row of carpal bones.
The eight carpal bones are arranged in prox- imal and distal rows of four bones each. Approximately 50 percent of movement at the wrist occurs at the wrist joint proper, with the remaining 50 percent occurring at the intercarpal joint, between the two rows of carpal bones. A capsule, reinforced by palmar and dorsal radiocarpal ligaments, sur- rounds the joint.
The radial collateral ligament strengthens the capsule lat- erally and limits adduction ulnar deviation. The ulnar collateral ligament strengthens the capsule medially and limits abduction radial deviation Figure In addition to the distal radioulnar joint, the proximal radioulnar joint allows pivot movement of the radius with the humerus and the ulna during prona- tion and supination.
The radius and ulna are also joined by the interosseous membrane and its fibers to form a syndesmosis. The individual fibers are attached proximally on the radius but distally on the ulna. Impact forces on an outstretched hand are transmitted at the wrist to the radius, through the interosseous membrane to the ulna, to the humerus, and then to the shoulder, which is attached to the trunk primarily by muscle. In this fashion, impact forces are transferred distally in the upper limb, with dissipation of the forces as they move proximally.
A fall on an outstretched hand may cause frac- ture of the radial head under the right circumstances. Fracture of one forearm bone frequently results in dislocation of the other bone through forces trans- ferred by the interosseous membrane. Articulations of the bones of the wrist. Reproduced, with permis- sion, from Lindner HH.
Clinical Anatomy. The anatomical snuff box is bounded anteriorly by the tendons of the abductor pollicis longus and the extensor pollicis brevis and posteriorly by the tendon of the extensor pollicis longus. The scaphoid bone and the radial artery a branch of which supplies the scaphoid lie in the floor of the snuff box. A carpal bone fracture is suspected. Which of the fol- lowing bones is most likely fractured?
Scaphoid B. Lunate C. Triquetrum D. Pisiform E. Which of the following is most likely to be the dislocated carpal bone? Capitate E. Hamate [3. Flexion B. Extension C. Abduction D. Adduction E. Pronation [3. Which of the following structures transmits the force from the radius to the ulna? Triangular fibrocartilage B. Interosseous membrane C. Scaphoid bone D. Ulnar collateral ligament E. Radial collateral ligament Answers [3.
The scaphoid bone is the most frequently fractured carpal bone. The lunate bone is the most frequently dislocated carpal bone. The medial or ulnar collateral ligament limits abduction or radial deviation of the wrist, which would be increased if the ligament were severely torn. The interosseous membrane conducts force from the radius to the ulna when the force originates from the wrist.
Philadelphia, PA: Saunders, plates —7. She notes some weakness of her right hand and has begun to drop items such as her coffee cup. She has otherwise been healthy and denies any trauma or neck pain. The carpal tunnel is a confined, rigid space at the wrist that contains nine tendons with their synovial sheaths and the median nerve. Any condition that further reduces the available space within the tunnel may compress the median nerve, producing numbness and pain in the areas of cutaneous distri- bution, muscle weakness especially in the thumb , and muscle atrophy after long-term compression.
However, we are not given the distribution of neu- ropathy of this case. The median nerve may be compressed in several sites along its length between the brachial plexus and the hand, but the carpal tun- nel is the most common site. Carpal tunnel syndrome has been associated with endocrine conditions such as diabetes, hypothyroidism, hyperthyroidism, acromegaly, and pregnancy.
Other causes include autoimmune disease, lipo- mas within the canal, hematomas, and carpal bone abnormalities. Females are more commonly affected than males in a ratio of Initial treatment is a nighttime splint of the wrist and avoidance of excessive activity with the hand.
If symptoms do not decrease, division of the flexor retinaculum carpal tunnel release may be necessary. Be able to describe the structures that form and pass through the carpal tunnel. Be able to describe the course, branches, and muscles innervated by the median nerve in the forearm and hand.
Be able to describe the skin areas supplied by the median nerve in the hand. Be able to describe the course of the ulnar nerve at the wrist as it relates to the carpal tunnel. Carpal tunnel syndrome: Entrapment of the median nerve within the carpal tunnel, resulting in pain, sensory paresthesia, and muscle weakness. Muscle atrophy: Wasting of muscle tissue, often the result of disuse sec- ondary to interference with its motor innervation.
The anterior boundary of the tunnel is formed by a thickening of the deep fascia, the flexor retinaculum transverse carpal ligament. The flexor retinaculum is attached laterally to the tubercles of the scaphoid and trapezium and medially to the pisiform and hook of the hamate. The carpal tunnel is a passageway for the nine tendons and their investing synovial sheaths of the flexor mus- cles of the thumb and fingers: four tendons each of the flexor digitorum superficialis FDS and flexor digitorum profundus FDP , the tendon of the flexor pollicis longus FPL , and the median nerve.
It passes distally along the arm with the brachial artery and enters the cubital fossa medial to that artery. The nerve is at some risk in the cubital fossa region. It enters the forearm by passing between the heads of the pronator teres muscle and then descends in the forearm between the FDS and the FDP.
In the forearm, the nerve innervates all the muscles of the anterior compartment except the flexor carpi ulnaris and the bellies of the FDP to the ring and little fingers. As it approaches the carpal tunnel at the wrist, the median nerve lies just medial to the tendon of the flexor carpi radialis muscle and slightly posterior to the tendon of the palmaris longus muscle, if it is present.
The median nerve enters the hand through the carpal tunnel together with the tendons of the FDS, FDP, and FPL and is at risk of laceration at the wrist and of compression within the carpal tunnel, deep to the flexor retinaculum transverse carpal ligament. Typically, the recurrent branch of the median nerve arises distal to the flexor retinaculum and the tunnel to innervate the three thenar muscles: flexor pollicis brevis, abduc- tor pollicis brevis, and the opponens pollicis.
The lumbrical muscles of the index and middle fingers receive their motor branches from adjacent com- mon palmar digital branches. The remainder of the median nerve divides into the common palmar dig- ital nerves to the skin of the thumb and the index, middle, and radial side of the ring fingers, including their dorsal nail beds. The skin of the palm of the hand and thenar eminence is supplied by the palmar cutaneous branch of the median nerve, which typically arises from the median nerve in the distal forearm and does not traverse the carpal tunnel.
Intact skin sensation in the palm of the hand suggests carpal tunnel entrapment of the median nerve, whereas loss of palmar skin sensation suggests a higher nerve lesion. Damage to the median nerve in the upper forearm results in loss of pronation, weakness in flexion at the wrist, and medial ulnar deviation. There will also be loss of flexion at the proximal interphalangeal joint of the index, middle, ring, and little fingers and loss of flexion at the distal interphalangeal joints of the index and middle fingers.
Damage to the median nerve in the upper forearm or at the wrist will also result in loss of flexion, abduction and opposition of the thumb, and flexion at the metacarpal phalangeal joints of the index and middle fingers. The ulnar nerve, which innervates all the other intrinsic hand muscles not noted above, enters the hand anterior to the flexor retinaculum with and medial to the ulnar artery. The artery and nerve are covered anteriorly by a condensation of the fascia of the forearm, called the volar carpal ligament.
Thus the ulnar nerve and artery come to lie in the Guyon canal, bounded ante- riorly by the volar carpal ligament, posteriorly by the flexor retinaculum, medially by the pisiform, and laterally by the hook of the hamate. The median nerve. Which of the following is the structure that forms the anterior wall of the tunnel? Palmar aponeurosis B.
Volar carpal ligament C. Flexor retinaculum D. Extensor retinaculum E. Deep fascia [4. Where is the median nerve located?
Just lateral to the flexor carpi radialis tendon B. Must medial to the flexor carpi radialis tendon C. Case Files: Anatomy provides 58 true-to-life cases thatillustrate essential concepts in this field. Each case includes an easy-tounderstand discussion correlated to essential basic science concepts, definitions of key terms, anatomy pearls, and USMLE-style review questions.
Experience with clinical cases is central to excelling on the USMLE Step 1 and shelf exams, and ultimately to providing patients with competent clinical care. Case Files: Anatomy provides 58 true-to-life cases thatillustrate essential concepts in this field.
Each case includes an easy-tounderstand discussion correlated to essential basic science concepts, definitions of key terms, anatomy pearls, and USMLE-style review questions. Learn from 58 high-yield cases, each with board-style questions and key-point pearls Master complex concepts through clear and concise discussions Practice with review questions to reinforce learning Polish your approach to clinical problem-solving Perfect for medical, dental, and physician assistant students preparing for gross anatomy course exams and the Boards.
Section II: Clinical Cases 1. Brachial Plexus Injury 2. Radial Nerve Injury 3. Wrist fracture 4. Carpal Tunnel Syndrome 5. Shoulder Dislocation 6. Posterior Hip Dislocation 7. Anterior Cruciate Ligament Rupture 8. Common Fibular Nerve Injury 9. Deep Venous Thrombosis
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