Lecture 9 Hand

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A patient presents with weakness in flexing their index and middle fingers, and a thenar eminence that appears flattened. Which nerve is MOST likely affected?

Ulnar nerve
Median nerve (correct)
Musculocutaneous nerve
Radial nerve

Following a bicycle accident, a cyclist has difficulty adducting their thumb and exhibits weakness in finger abduction and adduction. Which nerve is MOST likely injured?

Superficial branch of the radial nerve
Common digital branch of the ulnar nerve
Deep branch of the ulnar nerve (correct)
Proper digital nerves from the median nerve

A surgeon accidentally severs a nerve during a procedure near the wrist. Post-operatively, the patient cannot feel the skin on the back of their hand near the base of the thumb. Which nerve was MOST likely damaged?

Proper digital branch of the ulnar nerve
Superficial branch of the radial nerve (correct)
Deep branch of the ulnar nerve
Motor branch to the 3rd and 4th lumbricals

A patient has a lesion that affects the function of the 3rd and 4th lumbricals. Which nerve is MOST likely affected by this lesion?

Ulnar nerve (C) Signup and view all the answers

A patient displays a 'Hand of Benediction' when attempting to make a fist. Which nerve is MOST likely damaged and what specific function is lost that causes this sign?

Median nerve; loss of lumbrical function to digits 2 and 3 (A) Signup and view all the answers

Which of the following best describes the primary function enabled by the unique 90-degree rotation of the first digit (thumb)?

Opposition, allowing for grasping and manipulation. (B) Signup and view all the answers

A patient presents with limited hand movement after cast removal for a fractured forearm. Which carpal bone articulation is most likely restricted, impacting their ability to perform grasping movements?

Intercarpal articulations (C) Signup and view all the answers

Why is the 3rd metacarpal particularly vulnerable to fracture when punching a hard surface?

It is the longest of the metacarpal bones. (B) Signup and view all the answers

Which type of joint connects the phalanges, permitting flexion and extension exclusively?

Hinge joint (C) Signup and view all the answers

What is the functional significance of the fibrous digital sheaths that originate from the palmar aponeurosis?

They envelop flexor tendons, ensuring efficient gliding during finger flexion. (C) Signup and view all the answers

Dupuytren's contracture primarily affects which structure in the hand, leading to contracture of the 4th and 5th digits?

Palmar aponeurosis (D) Signup and view all the answers

What is the primary function of the flexor retinaculum?

To hold flexor tendons in place, preventing bowstringing (D) Signup and view all the answers

Which anatomical structure forms the roof of the carpal tunnel?

Flexor retinaculum (C) Signup and view all the answers

What is the function of the palmaris brevis muscle?

Wrinkling the skin over the hypothenar eminence and protecting the ulnar artery/nerve (B) Signup and view all the answers

Where are the digital flexor tendons located in relation to the palmar aponeurosis?

Deep to the palmar aponeurosis in the central compartment (D) Signup and view all the answers

What is the clinical significance of the midpalmar and thenar spaces?

They facilitate tendon gliding between compartments. (D) Signup and view all the answers

Which compartment houses the adductor pollicis muscle?

Adductor compartment (C) Signup and view all the answers

Despite their name, where are the dorsal interossei muscles located and considered to be part of?

Located between metacarpals and considered part of the palmar surface (A) Signup and view all the answers

A patient has difficulty with precision movements of the thumb, particularly opposition. Which group of muscles is most likely affected?

Thenar muscles (C) Signup and view all the answers

Where do the thenar muscles typically originate?

Flexor Retinaculum and lateral carpal bones (A) Signup and view all the answers

Which of the following muscles contributes to the complex movement of thumb opposition, drawing the pulp of the thumb towards the other fingers?

Opponens Pollicis (C) Signup and view all the answers

A patient presents with weakness in thumb adduction. Which muscle is MOST likely affected?

Adductor Pollicis (C) Signup and view all the answers

Following a laceration on the medial side of the hypothenar eminence, a patient experiences difficulty abducting their little finger. Which muscle is MOST likely injured?

Abductor Digiti Minimi (C) Signup and view all the answers

What is the MOST likely consequence of paralysis affecting both lumbrical and interossei muscles?

Claw finger/hand deformity (C) Signup and view all the answers

Which of the following statements BEST describes the function of the palmar interossei muscles?

Adduction of digits 2, 4, and 5 towards digit 3 (D) Signup and view all the answers

During a hand surgery, the surgeon identifies a structure bifurcating and attaching bilaterally to the base of the middle phalanges. Which tendon is the surgeon MOST likely observing?

Flexor Digitorum Superficialis Tendon (B) Signup and view all the answers

The central band of the extensor digitorum tendon inserts at the base of which phalanx?

Middle phalanx (D) Signup and view all the answers

A patient is diagnosed with tenosynovitis in the synovial sheath of the 5th digit. Which anatomical structure allows this infection to potentially spread to the carpal tunnel?

Continuous synovial sheath between the 5th digit and the common flexor sheath (A) Signup and view all the answers

What is Raynaud syndrome?

Idiopathic ischemia of digital arteries, typically in response to cold or stress (B) Signup and view all the answers

Which artery is typically compressed to prevent excessive bleeding during surgical repair of severe lacerations to arteries of the hand?

Brachial artery (D) Signup and view all the answers

What is the MOST likely outcome of damage to the recurrent branch of the median nerve?

Loss of function in the thenar eminence progressing to ape-hand deformity (D) Signup and view all the answers

Which of the following structures is NOT located within the carpal tunnel?

Extensor Digitorum Tendons (B) Signup and view all the answers

Which artery provides the primary blood supply to the lateral aspect of the second digit (index finger)?

Radialis indicis artery (A) Signup and view all the answers

What is the primary function of the fibrous sheath that covers the flexor tendons in the hand?

To prevent bowstringing of the tendons during flexion (B) Signup and view all the answers

In the context of the superficial and deep palmar arches, which statement BEST describes the contribution of the radial and ulnar arteries?

The superficial palmar arch is primarily ulnar artery dominant, while the deep palmar arch is primarily radial artery dominant. (B) Signup and view all the answers

A patient presents with decreased sensation on the dorsal surface of their hand near the base of the thumb, but no motor deficits. Which nerve is MOST likely affected?

Superficial branch of the radial nerve (A) Signup and view all the answers

A surgeon is performing a carpal tunnel release and accidentally damages a nerve. Post-operatively, the patient exhibits weakness in flexing digits 2 and 3. Which of the following is the MOST likely nerve damaged?

Median nerve (C) Signup and view all the answers

After a knife wound to the wrist, a patient demonstrates weakness in adduction of the thumb and difficulty with finger abduction and adduction. Which nerve is MOST likely injured?

Ulnar nerve (A) Signup and view all the answers

A patient has loss of sensation in their fifth digit and the medial half of their fourth digit. Which nerve is MOST likely affected?

Ulnar nerve (C) Signup and view all the answers

Following a crush injury to the hand, a patient demonstrates a clawing of the 4th and 5th digits. Which nerve is MOST likely damaged?

Ulnar nerve (A) Signup and view all the answers

What specific movement is primarily generated by the opponens pollicis muscle?

Flexion and internal rotation of the thumb at the carpometacarpal joint. (D) Signup and view all the answers

Which statement accurately describes the location and function of the abductor digiti minimi?

Found superficial and medial in the hypothenar eminence, it abducts the metacarpophalangeal joint of the little finger. (C) Signup and view all the answers

What is the primary action of palmar interossei muscles?

Adduction of digits 2, 4, and 5 towards the midline of the hand. (D) Signup and view all the answers

What key feature distinguishes the dorsal interossei muscles from the palmar interossei muscles in terms of their action on the digits?

Dorsal interossei abduct the digits, while palmar interossei adduct them. (D) Signup and view all the answers

How do the tendons of the Flexor Digitorum Superficialis (FDS) and Flexor Digitorum Profundus (FDP) interact in the region of the proximal interphalangeal joint?

The FDS tendon bifurcates and attaches to the base of the middle phalanx, allowing the FDP tendon to pass through and insert on the distal phalanx. (A) Signup and view all the answers

A patient presents with trigger finger in their right index finger. Which anatomical structure is MOST likely involved in this condition?

Thickening and stenosis of the fibrous sheath surrounding the flexor tendons. (B) Signup and view all the answers

Why is compression of the brachial artery often necessary during surgical repair of severe hand lacerations?

To minimize excessive bleeding due to the extensive arterial anastomoses in the hand. (D) Signup and view all the answers

What is the primary source of blood supply to the lateral aspect of the second digit (index finger)?

Radialis indicis artery. (A) Signup and view all the answers

How does the arrangement of the digital synovial sheaths contribute to the potential spread of infection in the hand?

The synovial sheath of the 5th digit is continuous with the common flexor sheath, allowing infection to spread to the carpal tunnel. (D) Signup and view all the answers

What is the most likely consequence of damage to the recurrent branch of the median nerve?

Impaired function of the thenar muscles, progressing to ape-hand deformity. (E) Signup and view all the answers

A patient has difficulty flexing at the MCP joint and extending at the interphalangeal joints. Which muscle group is MOST likely affected?

Lumbricals and interossei. (C) Signup and view all the answers

A patient is diagnosed carpal tunnel syndrome. What anatomical structure is directly affected in this condition?

The median nerve. (A) Signup and view all the answers

How does the origin of the two lateral lumbricals differ from the two medial lumbricals?

The lateral lumbricals have a single origin off the tendons to the 2nd and 3rd digits, while the medial lumbricals have a bipennate origin off the tendons to digits 3 through 5. (A) Signup and view all the answers

A patient presents with idiopathic ischemia of the digital arteries in response to cold exposure. Which condition is MOST consistent with these symptoms?

Raynaud syndrome. (A) Signup and view all the answers

Which carpal bone articulates directly with the radius?

Lunate (A) Signup and view all the answers

Following a wrist fracture and subsequent cast removal, a patient is experiencing difficulty with fine motor movements of their hand. Which of the following interventions would BEST address the underlying cause of this difficulty?

Carpal joint mobilization (D) Signup and view all the answers

A boxer sustains a fracture at the base of their 3rd metacarpal. Why is the 3rd metacarpal particularly vulnerable to this type of injury?

The 3rd metacarpal is relatively long and exposed. (C) Signup and view all the answers

Which type of joint is found between the metacarpals and phalanges, allowing for flexion, extension, abduction, and adduction of the fingers?

Condyloid (D) Signup and view all the answers

What is the primary function of the fibrous digital sheaths found on the palmar side of the digits?

To facilitate the gliding of flexor tendons (B) Signup and view all the answers

Dupuytren's contracture, a condition affecting the palmar fascia, primarily results in the contracture of which digits?

4th and 5th (B) Signup and view all the answers

The flexor retinaculum, a key structure in the wrist, spans between which two bony landmarks?

Scaphoid/Trapezium to Pisiform/Hook of Hamate (A) Signup and view all the answers

What is the functional significance of the palmaris brevis muscle?

It wrinkles the skin over the hypothenar eminence and protects the ulnar artery/nerve. (A) Signup and view all the answers

Which statement accurately describes the dorsal fascia of the hand compared to the palmar fascia?

The dorsal fascia is thinner than the palmar fascia and primarily thickens at the extensor retinaculum. (C) Signup and view all the answers

The midpalmar space is located between which two compartments of the hand?

Central and Interosseous compartments (C) Signup and view all the answers

Despite their name, where are the dorsal interossei muscles located in relation to the palmar surface of the hand?

They are considered part of the palmar surface, located between the metacarpals. (A) Signup and view all the answers

What is the common origin of the thenar muscles?

Flexor retinaculum and lateral carpal bones (D) Signup and view all the answers

Which of the following lists the carpal bones in the proximal row, from radial to ulnar?

Scaphoid, Lunate, Triquetrum, Pisiform (B) Signup and view all the answers

In a patient presenting with difficulty flexing their distal interphalangeal (DIP) joint of the index finger, which compartment and associated tendons are MOST likely involved?

Central compartment; flexor digitorum profundus (A) Signup and view all the answers

Median Nerve (Hand)

Supplies motor function to lumbricals 1 and 2, which contribute to flexion at the MCP joint and extension at the IP joints of digits 2 and 3.

"Hand of Benediction"

Inability to fully flex digits 2 and 3 when making a fist, due to loss of function in lumbricals 1 and 2.

Deep Branch of Ulnar Nerve

Supplies motor branches to the interossei, adductor pollicis, and deep head of the flexor pollicis brevis, intrinsic muscles of the hand.

Ulnar Nerve Injury

Most of the hand muscles are supplied; injury results in significant loss of hand function and "ulnar nerve claw" deformity, affecting digits 4 and 5 more severely.