Snell Hand Anatomy Quiz

Questions and Answers

Which compartment of the hand primarily contains muscles involved in thumb opposition?

Thenar compartment (correct)

Hypothenar compartment

Interosseous compartment

Dorsal/extensor compartment

What differentiates intrinsic muscles from extrinsic muscles in the hand?

Intrinsic muscles originate in the forearm.

Extrinsic muscles insert within the hand.

Intrinsic muscles both originate and insert within the hand. (correct)

Extrinsic muscles are located in the palmar aspect only.

Which of the following structures is NOT located in the palmar aspect of the hand?

Interosseous compartment

Deep palmar arch

Thenar compartment

Dorsal/Extensor compartment (correct)

Which of the following describes the relationship between extrinsic muscles and tendons in the hand?

Extrinsic muscles originate outside the hand and insert within it via long tendons. Signup and view all the answers

Which muscle group is majorly responsible for movement within the central compartment of the hand?

Interossei muscles Signup and view all the answers

Which muscle is responsible for pulling the thumb medially and forward?

Opponens pollicis Signup and view all the answers

What is the origin of the adductor pollicis?

Second and third metacarpal bones Signup and view all the answers

What is the primary cause of tenosynovitis of flexor tendons?

Infection due to bacterial entry through a penetrating wound Signup and view all the answers

Which statement accurately describes the lumbrical muscles?

Each lumbrical is numbered from lateral to medial, but attached to its corresponding digit. Signup and view all the answers

Which nerve supplies the abductor digiti minimi?

Deep branch of ulnar nerve Signup and view all the answers

What is the primary function of the palmaris brevis?

To corrugate the skin at the base of the hypothenar eminence Signup and view all the answers

Which muscle action primarily involves abducting the little finger?

Abductor digiti minimi Signup and view all the answers

Which tendon arrangement results in the 'buttonhole effect'?

Superficialis tendon splitting to accommodate the profundus tendon Signup and view all the answers

Which structure acts as a strong fibrous sheath attached to the sides of the phalanges?

Fibrous flexor sheath Signup and view all the answers

What action does the opponens digiti minimi perform?

Pulls the fifth metacarpal forward Signup and view all the answers

How many interosseous muscles are present in the hand?

Eight Signup and view all the answers

Which nerve roots primarily supply the muscles of the little finger?

C8; T1 Signup and view all the answers

What occurs if the pressure within a tenosynovial sheath rises significantly?

It may compress the blood supply to the tendons Signup and view all the answers

Which of the following statements about the interosseous muscles is incorrect?

The interosseous muscles attach directly to the proximal phalanx only. Signup and view all the answers

In the thumb, what does the osseofibrous tunnel contain?

Tendon of flexor pollicis longus Signup and view all the answers

Which structure does the tendon of the flexor digitorum profundus pass through?

The split of the flexor digitorum superficialis tendon Signup and view all the answers

What is the effect of tenosynovitis on finger movement?

It causes extreme pain upon extension of the finger. Signup and view all the answers

What is the function of the interosseous muscles during finger movements?

To produce flexion at the metacarpophalangeal joints and extension at the interphalangeal joints Signup and view all the answers

Which muscle does NOT belong to the hypothenar compartment?

Abductor pollicis brevis Signup and view all the answers

What is the primary action of the dorsal interossei?

Abduction of fingers Signup and view all the answers

Which nerve supplies the adductor pollicis muscle?

Ulnar nerve (deep branch) Signup and view all the answers

What is the action of the palmaris brevis muscle?

Improves grip of the palm Signup and view all the answers

Which intrinsic hand muscle is responsible for flexing the metacarpophalangeal joints and extending the interphalangeal joints of the fingers except the thumb?

Lumbricals Signup and view all the answers

Which of the following muscles is NOT innervated by the ulnar nerve?

Flexor pollicis brevis Signup and view all the answers

Which muscle's origin is from the anterior surface of the shafts of metacarpal bones?

Palmar interossei Signup and view all the answers

What specific function does the opponens pollicis serve?

Opposition of the thumb Signup and view all the answers

What is the main consequence of delayed diagnosis in forearm compartment syndrome?

Permanent muscle damage after four hours Signup and view all the answers

Which muscles are primarily affected in Volkmann's ischemic contracture?

Flexor muscles of the forearm Signup and view all the answers

What is a common cause of tennis elbow?

Partial tearing of the superficial extensor muscles Signup and view all the answers

What condition arises from edema and fibrosis of the synovial sheath of the abductor pollicis longus and extensor pollicis brevis tendons?

Stenosing tenosynovitis Signup and view all the answers

What is the typical result of a rupture of the extensor pollicis longus tendon?

Excessive friction on the tendon Signup and view all the answers

Which sign is NOT an early indicator of forearm compartment syndrome?

Clawing of the fingers Signup and view all the answers

What is the main action of the biceps brachii muscle?

Flexor of elbow joint Signup and view all the answers

Which nerve supplies the brachialis muscle?

Musculocutaneous nerve Signup and view all the answers

What anatomical structure is commonly associated with the absence of the palmaris longus?

Flexor digitorum superficialis Signup and view all the answers

Which muscle's action includes both flexion and adduction at the wrist joint?

Flexor Carpi Ulnaris Signup and view all the answers

What is the origin of the long head of the triceps muscle?

Infraglenoid tubercle of scapula Signup and view all the answers

Which type of deformity occurs when both flexor and extensor muscles are contracted historically?

Flexed wrist, extended metacarpophalangeal joints Signup and view all the answers

What is the primary action performed by the Pronator Teres?

Pronates the forearm Signup and view all the answers

What leads to localized ischemic necrosis in Volkmann's ischemic contracture?

Arterial spasm reducing blood flow Signup and view all the answers

Which muscle group mainly produces flexion or pronation in the forearm?

Anterior compartment muscles Signup and view all the answers

Which nerve supplies both the Flexor Carpi Radialis and the Palmaris Longus?

Median nerve Signup and view all the answers

Which of the following muscles is considered part of the superficial group of the anterior compartment?

Flexor carpi radialis Signup and view all the answers

What characteristic symptom is associated with tennis elbow?

Radiating pain down the forearm Signup and view all the answers

Which muscle can flex the distal phalanx of the thumb?

Flexor Pollicis Longus Signup and view all the answers

What is the primary action of the lateral head of the triceps muscle?

Extension of elbow joint Signup and view all the answers

Which muscle is primarily responsible for flexing the middle phalanx of the medial four fingers?

Flexor Digitorum Superficialis Signup and view all the answers

Which nerve is responsible for innervating the muscles in the lateral compartment of the forearm?

Radial nerve Signup and view all the answers

What is a common origin for the muscles in the superficial group of the anterior compartment?

Medial epicondyle of humerus Signup and view all the answers

Which muscle originates from the medial epicondyle of the humerus and the medial border of the coronoid process of the ulna?

Flexor Digitorum Superficialis Signup and view all the answers

Which muscle is innervated by the anterior interosseous branch of the median nerve?

Flexor Pollicis Longus Signup and view all the answers

Which pair of muscles acts to flex the distal phalanx of the fingers?

Flexor Digitorum Profundus and Flexor Pollicis Longus Signup and view all the answers

Which muscle primarily acts to flex the forearm at the elbow joint?

Brachioradialis Signup and view all the answers

Which nerve supplies the extensor pollicis longus muscle?

Deep branch of radial nerve Signup and view all the answers

What is the primary action of the extensor carpi ulnaris?

Extends and adducts the hand at the wrist joint Signup and view all the answers

Which muscle's origin is from the lateral supracondylar ridge of the humerus?

Brachioradialis Signup and view all the answers

What is the predominant nerve root supply for the extensor carpi radialis longus?

C6, 7 Signup and view all the answers

Which structure is responsible for extending the metacarpophalangeal joint of the little finger?

Extensor digiti minimi Signup and view all the answers

What is the action of the supinator muscle?

Supinates the forearm Signup and view all the answers

Which muscle primarily assists in abduction and extension of the thumb?

Abductor pollicis longus Signup and view all the answers

What is the primary function of the synovial flexor sheaths in the hand?

Facilitate smooth tendon movement with minimal friction Signup and view all the answers

Which statement correctly describes the relationship between the flexor pollicis longus tendon and the common synovial sheath?

It communicates with the common synovial sheath in approximately 50% of subjects. Signup and view all the answers

What anatomical structure contains the tendon of the flexor pollicis longus?

Osseofibrous tunnel Signup and view all the answers

How do the fibrous and synovial sheath structures differ?

Fibrous sheaths are thick over the phalanges, while synovial sheaths provide tendon lubrication. Signup and view all the answers

What role do the vincula longa and brevia serve in relation to the tendons?

Convey blood vessels to the tendons Signup and view all the answers

Which tendons invaginate a common synovial sheath from the lateral side?

Flexor digitorum superficialis and flexor digitorum profundus Signup and view all the answers

Where does the lateral part of the common synovial sheath stop?

Abruptly at the middle of the palm Signup and view all the answers

In which location are the fibrous sheaths the thickest?

Over the phalanges of the fingers Signup and view all the answers

Which structure lies between the thenar and midpalmar spaces?

Medial fibrous septum Signup and view all the answers

What is a potential consequence of infection in the fascial spaces of the palm?

Distension with pus Signup and view all the answers

Which muscle is found in the thenar space?

First lumbrical muscle Signup and view all the answers

How is the blood supply to the terminal phalanx structured?

Both the diaphysis and epiphysis receive branches from the digital artery. Signup and view all the answers

What role does the palmar aponeurosis play in the palm?

Divides the palm into thenar and midpalmar spaces Signup and view all the answers

Which structural feature helps prevent infection spread in the fingers?

Septa within the pulp space Signup and view all the answers

What primarily occupies each pulp space in the fingers?

Connective tissue and fat Signup and view all the answers

What structure is closed off from the forearm by the walls of the carpal tunnel?

Thenar and midpalmar spaces Signup and view all the answers

Study Notes

Osseofascial Compartments of the Hand

The hand contains both extrinsic muscles (originating from the forearm) and intrinsic muscles (originating and inserting within the hand).
Organized into five compartments: thenar, hypothenar, central (midpalmar), interosseous (palmar and dorsal), and extensor (dorsal aspect).
Thenar compartment includes muscles related to thumb movement; hypothenar is responsible for little finger mobility.

Tenosynovitis

Tenosynovitis arises from bacterial infection in synovial sheaths, typically via penetrating wounds.
Symptoms include finger swelling, pain on extension, and semi-flexed positions due to pus distention.
If untreated, increased pressure might lead to tendon ischemia and potential rupture.

Flexor Tendon Anatomy

Flexor digitorum superficialis splits into two halves around tendeons of the flexor digitorum profundus, creating the "buttonhole effect."
Each superficialis tendon re-divides into slips toward the middle phalanx, while the profundus tendon attaches to the distal phalanx.

Palmaris Brevis Muscle

Palmaris brevis originates from the flexor retinaculum, improving grip by corrugating skin at hypothenar.
Innervation via the superficial branch of the ulnar nerve.

Lumbrical Muscles

Four lumbricals arise from flexor digitorum profundus tendons, inserting into digits 2-5.
They flex metacarpophalangeal joints while extending interphalangeal joints, identified by position (medial to lateral).

Interosseous Muscles

Composed of eight muscles: four palmar (adduct fingers towards the third digit) and four dorsal (abduct fingers away).
Innervated by the deep branch of the ulnar nerve.

Synovial Flexor Sheaths

Flexor tendons of the hand are sheathed in synovial membranes, allowing smooth movement.
Sheath continuity differs between digits; the little finger has uninterrupted sheath, while the index, middle, and ring fingers acquire individual sheaths.

Fibrous Flexor Sheaths

Each finger has a fibrous sheath that attaches to phalanges, facilitating tendon movement and stability.
The sheath's thick over phalanges and closes around the distal phalanx.

Clinical Considerations

Early detection of compartment syndrome in the forearm is crucial due to secondary blood vessel compression.
Symptoms include altered sensation, disproportionate pain, and tenderness. Delay in intervention can lead to irreversible muscle damage.
Volkmann's contracture may follow forearm fractures, causing deformities based on muscle group contractions.

Muscle Tables

Intrinsic Muscles of the Hand: Includes the palmaris brevis, lumbricals, and interossei, each with a specific origin, insertion, innervation, and function.
Short Muscles of the Thumb: Abductor pollicis brevis, flexor pollicis brevis support thumb mobilization and are innervated primarily by the median and ulnar nerves.
Muscles of the Anterior Forearm: Comprised of various flexor muscles, innervated by the median and ulnar nerves, facilitating flexion and pronation at wrist and elbow.

Summary of Forearm Muscles

Organized into anterior, lateral, and posterior compartments impacting elbow and wrist functions.
Anterior compartment predominantly flexes and pronates, while lateral and posterior principally extend and supinate.
Comprised of key muscles including biceps brachii, triceps, and various flexors relating to wrist and digit movement.### Anterior Osseofascial Compartment Muscles
Muscles are categorized into superficial, intermediate, and deep groups.
Superficial group: Includes flexor carpi ulnaris, palmaris longus, flexor carpi radialis, and pronator teres, all sharing a common tendon of origin from the medial epicondyle of the humerus.
Intermediate group: Comprises the flexor digitorum superficialis.
Deep group: Features flexor digitorum profundus, flexor pollicis longus, and pronator quadratus.

Lateral Osseofascial Compartment Muscles

Contains two main muscles: brachioradialis and extensor carpi radialis longus.
Some classifications consider this group as part of the posterior compartment.
Brachioradialis:
- Origin: Lateral supracondylar ridge of humerus
- Insertion: Base of styloid process of radius
- Action: Flexes the forearm and rotates to midprone position.
Extensor carpi radialis longus:
- Origin: Lateral supracondylar ridge of humerus
- Insertion: Base of second metacarpal
- Action: Extends and abducts the hand at the wrist.

Posterior Forearm Osseofascial Compartment Muscles

Extensor carpi radialis brevis: Extends and abducts the hand; originates from the lateral epicondyle.
Extensor digitorum: Extends fingers and hand; affects the medial four fingers.
Extensor digiti minimi: Specifically extends the little finger.
Extensor carpi ulnaris: Extends and adducts the hand; inserts at the base of the fifth metacarpal.
Anconeus: Extends the elbow joint; extends from lateral epicondyle to ulna.
Supinator: Supinates the forearm; works with the deep branch of the radial nerve.
Abductor pollicis longus: Abducts and extends the thumb.
Extensor pollicis brevis: Extends the thumb at the metacarpophalangeal joint.
Extensor pollicis longus: Extends the distal phalanx of the thumb.
Extensor indicis: Extends the index finger.

Clinical Notes on Compartment Syndrome

Compartment syndrome occurs due to edema causing compression within tight forearm compartments.
Initially affects vein compression, followed by arterial compression.
Commonly caused by soft tissue injury; early detection is vital.

Fascial Spaces of the Palm and Infection

The fascial spaces are significant as they can become infected, leading to conditions such as acute suppurative tenosynovitis.
Infections may arise from penetrating injuries, such as dirty nails.
Finger pulp spaces: Each pulp space is enclosed; subdivided by septa passing from deep fascia to the periosteum.

Palmar and Pulp Fascial Spaces

The wrist and palm have thickened deep fascia forming structures like the flexor retinaculum and palmar aponeurosis.
Palmar aponeurosis: A triangular structure dividing the palm into the thenar and midpalmar spaces.
The thenar space contains the first lumbrical muscle, while the midpalmar space hosts the second, third, and fourth lumbrical muscles.
Lumbrical canals surround each lumbrical muscle tendon, normally filled with connective tissue and continuous with palmar spaces.

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Description

Test your knowledge on the anatomy of the hand, particularly focusing on the muscles involved in thumb opposition and the differences between intrinsic and extrinsic muscles. This quiz covers the structures located in the palmar aspect of the hand and the relationship between muscle groups and their tendons.