Muscles of the Hand Anatomy Quiz

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Questions and Answers

What is the primary nerve supply for the dorsal interossei muscles?

Deep branch of ulnar nerve (correct)

Median nerve

Radial nerve

Musculocutaneous nerve

How many abductors are present for the pollex?

1 (correct)

Which finger does the 1st dorsal interossei muscle primarily insert into?

Thumb

Ring finger

Middle finger

Index finger (correct)

In terms of action, what is the primary function of the dorsal interossei muscles?

Abduction of the fingers Signup and view all the answers

Which of the following statements is true about the organization of the dorsal interossei?

They are arranged from lateral to medial. Signup and view all the answers

How many adductors are present for the digiti minimi?

1 Signup and view all the answers

The insertion point for the 4th dorsal interossei muscle is located on which part of the hand?

Medial side of the ring finger Signup and view all the answers

What is the origin of the dorsal interossei muscles?

Shafts of adjacent metacarpal bones Signup and view all the answers

What is the primary role of the intrinsic muscles of the hand?

To execute precision movements with fingers and thumb Signup and view all the answers

Which of the following muscles is NOT categorized as a thenar muscle?

Adductor Pollicis Signup and view all the answers

Which of the following statements about innervation of the intrinsic muscles of the hand is true?

The deep branch of the ulnar nerve innervates most intrinsic muscles Signup and view all the answers

What distinguishes dorsal interossei muscles from palmar interossei muscles?

Dorsal interossei facilitate abduction and palmar interossei facilitate adduction Signup and view all the answers

How many lumbrical muscles are present in the hand?

Four Signup and view all the answers

Which muscle is responsible for the abduction of the little finger?

Abductor Digiti Minimi Signup and view all the answers

What is the relationship between the thenar muscles and other intrinsic muscles regarding innervation?

Thenar muscles are solely innervated by the median nerve, unlike other intrinsic muscles Signup and view all the answers

Which muscles contribute to the precision grip of the fingers?

Intrinsic muscles of the hand Signup and view all the answers

What is the primary action of the palmar interossei muscles?

Adduct the thumb, index, ring, and little fingers Signup and view all the answers

Which palmar interosseus is considered rudimentary and has a specific origin?

1st palmar interosseus from the medial side of metacarpal I Signup and view all the answers

What is the nerve supply for the palmar interossei?

Deep branch of ulnar nerve Signup and view all the answers

Where do the 3rd and 4th palmar interossei insert?

Lateral sides of the extensor hoods of the respective fingers Signup and view all the answers

From where do the lumbricals originate?

The tendons of the flexor digitorum profundus Signup and view all the answers

Which lumbricals are associated with the index and middle fingers?

1st and 2nd Signup and view all the answers

In what arrangement are the palmar interossei numbered?

Lateral to medial Signup and view all the answers

What joint movements do the palmar interossei primarily act upon?

Metacarpophalangeal joints Signup and view all the answers

Which carpal bone is most likely fractured when a patient presents with pain in the floor of the anatomical snuffbox?

Scaphoid Signup and view all the answers

What clinical significance does the anatomical snuffbox have apart from the palpability of the scaphoid?

Area where radial artery pulse can be felt Signup and view all the answers

What mechanism of injury is commonly associated with scaphoid fractures in athletes?

Fall with the wrist in extension Signup and view all the answers

Which of the following carpal bones is least likely to be involved in a wrist fracture presenting with pain in the anatomical snuffbox?

Trapezoid Signup and view all the answers

In context of hand injuries, why is the scaphoid bone particularly significant?

It has a high rate of non-union after fracture Signup and view all the answers

What is the primary function of the lumbricals in the hand?

Flex the metacarpophalangeal joints and extend interphalangeal joints Signup and view all the answers

Which nerve innervates the 1st and 2nd lumbricals?

Muscular and cutaneous branches of the median nerve Signup and view all the answers

What structure does the extensor hood NOT include?

Flexor carpi ulnaris tendon Signup and view all the answers

Where does the apex of each extensor hood point?

Distally towards the tip of the fingers Signup and view all the answers

What do the collateral ligaments of the extensor hood attach to?

The distal phalanx Signup and view all the answers

Which of the following correctly describes the base of the extensor hood?

It is directed distally and wrapped around the sides of the metacarpophalangeal joint Signup and view all the answers

What is the origin of the 3rd and 4th lumbricals?

From the sides of flexor digitorum profundus tendons associated with the respective fingers Signup and view all the answers

In terms of their insertion, how are lumbricals unique?

They link flexor tendons with extensor tendons Signup and view all the answers

Study Notes

### Muscles of the Hand

The muscles of the hand are divided into superficial and deep muscles.
Superficial muscles include:Palmaris Brevis, Thenar muscles, Intermediate muscles, Hypothenar muscles.
Deep intrinsic muscles of the hand include: Thenar muscles, Intermediate muscles, Hypothenar muscles.
Thenar muscles include: Abductor Pollicis Brevis, Flexor Pollicis Brevis, Opponens Pollicis.
Intermediate muscles include: Adductor Pollicis, Four Dorsal Interossei, Four Palmar Interossei.
Hypothenar muscles include: Abductor Digiti Minimi, Flexor Digiti Minimi, Opponens Digiti Minimi.
The deep intrinsic muscles of the hand are mainly responsible for precision movements of the fingers and thumb.
The deep intrinsic muscles of the hand are innervated by the deep branch of the ulnar nerve, except for the following which are innervated by the median nerve: 1) Three thenar muscles. 2) Two lateral lumbrical muscles.

Interossei and Lumbrical muscles
Dorsal interossei have double heads and are abductors.
Palmar interossei have single heads and are adductors.
Dorsal Interossei:
- There are 4 dorsal interossei.
- They are located on the dorsum of the hand.
- They originate from the shafts of two adjacent metacarpal bones.
- The insertion of the dorsal interossei muscles depends on their position:
  - 1st dorsal interossei is inserted onto the lateral side of the index finger.
  - 2nd and 3rd dorsal interossei are inserted onto the lateral and medial sides of the middle finger, respectively.
  - 4th dorsal interossei is inserted onto the medial side of the ring finger.
- The dorsal interossei are innervated by the deep branch of the ulnar nerve.
- This muscle group functions to abduct the index, middle, and ring fingers at the metacarpophalangeal joints.
Palmar Interossei:
- There are 3 (or four) palmar interossei muscles.
- They are found in the anterior to the dorsal interossei.
- They originate from the metacarpal bones.
- The insertion of the palmar interossei muscles depends on their position:
  - 1st palmar interossei is rudimentary. If present, it originates from the medial side of the palmar surface of metacarpal I and is inserted onto both the base of the proximal phalanx of the thumb and the extensor hood.
  - 2nd palmar interossei originates from the medial surface of metacarpal II and is inserted onto the medial side of the extensor hood of the index finger.
  - 3rd and 4th palmar interossei originate from the lateral surfaces of metacarpals IV and V, respectively, and are inserted onto the respective lateral sides of the extensor hoods.
- Palmar interossei are innervated by the deep branch of the ulnar nerve.
- They adduct the thumb, index, ring, and little fingers at the metacarpophalangeal joint.
Lumbricals:
- There are four lumbricals.
- They are arranged from lateral to medial.
- They originate from the tendons of the flexor digitorum profundus in the palm, with 1st and 2nd lumbricals originating from the lateral side of the flexor digitorum profundus tendons associated with the index and middle fingers, respectively, and the 3rd and 4th lumbricals originating from the sides of the flexor digitorum profundus tendons associated with the middle and ring fingers and the ring and little fingers , respectively.
- The insertion of all lumbrical muscles is onto the extensor hood.
- The lumbricals connect flexor tendons with extensor tendons.
- The 1st and 2nd lumbrical muscles are innervated by the muscular and cutaneous branches of the median nerve in the hand.
- The 3rd and 4th lumbrical muscles are innervated by the deep branch of the ulnar nerve in the hand.
- The lumbricals flex the metacarpophalangeal joint and extend the interphalangeal joint.
Extensor Hood
The extensor hood, also known as the dorsal digital expansion, is a connective tissue mass that is formed by the tendons of all the long extensors of the forearm, the interossei, and the lumbricals.
The extensor hood extends over the proximal phalanx to form the "extensor hood" which has two collateral ligaments, a central ligament, and a base.
The extensor hood flexes the metacarpophalangeal joints and extends the interphalangeal joints.

Clinical Correlation

The scaphoid bone is palpable in the anatomical snuffbox.
The anatomical snuffbox is the depression on the radial, dorsal aspect of the hand, formed by the tendons of the abductor pollicis longus and extensor pollicis brevis.
Assessing the snuffbox can help diagnose a scaphoid fracture.
This position also allows for the palpation of the radial artery pulse.

Clinical Case

A 25-year-old male athlete presented with a fractured carpal bone in the floor of the anatomical snuffbox after a bad landing. The fractured bone is likely to be the scaphoid bone.

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Description

Test your knowledge on the muscles of the hand, including the superficial and deep intrinsic muscles. This quiz covers detailed information about the thenar, hypothenar, interossei, and lumbrical muscles, their functions, and innervation. Perfect for students and professionals in anatomy and physiotherapy!