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Questions and Answers
Which bone is located on the lateral side of the forearm?
Which bone is located on the lateral side of the forearm?
What is the function of the pivoting of the radius?
What is the function of the pivoting of the radius?
Which of the following correctly describes the ulna's position?
Which of the following correctly describes the ulna's position?
How many carpal bones are there in the wrist?
How many carpal bones are there in the wrist?
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Which of the following bones is NOT part of the hand's 19 bones?
Which of the following bones is NOT part of the hand's 19 bones?
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Which bone is the longer of the two in the forearm?
Which bone is the longer of the two in the forearm?
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What describes the shape of the shafts of the radius and ulna on cross section?
What describes the shape of the shafts of the radius and ulna on cross section?
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Which end of the ulna is wider?
Which end of the ulna is wider?
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What role does the ulna serve during pronation and supination?
What role does the ulna serve during pronation and supination?
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Which feature is NOT associated with the radius?
Which feature is NOT associated with the radius?
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What is the significance of the olecranon in relation to the ulna?
What is the significance of the olecranon in relation to the ulna?
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Which border of the ulna shaft is associated with being anterior?
Which border of the ulna shaft is associated with being anterior?
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What is the primary characteristic of the radius's proximal end?
What is the primary characteristic of the radius's proximal end?
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What characteristic distinguishes the distal ulna?
What characteristic distinguishes the distal ulna?
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Which structure articulates with the rounded head of the distal ulna?
Which structure articulates with the rounded head of the distal ulna?
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What is the primary function of the styloid process on the ulna?
What is the primary function of the styloid process on the ulna?
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What shape is the proximal end of the radius described as?
What shape is the proximal end of the radius described as?
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Which statement is correct regarding the movement of the radius during pronation and supination?
Which statement is correct regarding the movement of the radius during pronation and supination?
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What structure fits into the olecranon fossa of the humerus?
What structure fits into the olecranon fossa of the humerus?
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Which part of the ulna articulates with the radial head?
Which part of the ulna articulates with the radial head?
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What type of joint is formed by the interosseous membrane?
What type of joint is formed by the interosseous membrane?
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Which of the following structures serves as the attachment site for the brachialis muscle?
Which of the following structures serves as the attachment site for the brachialis muscle?
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What is the primary function of the interosseous membrane?
What is the primary function of the interosseous membrane?
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Which structure of the proximal ulna articulates with the trochlea of the humerus?
Which structure of the proximal ulna articulates with the trochlea of the humerus?
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What is the function of the supinator crest?
What is the function of the supinator crest?
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Which of the following borders the interosseous membrane?
Which of the following borders the interosseous membrane?
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What is the primary function of sesamoids in tendons?
What is the primary function of sesamoids in tendons?
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Which of the following sesamoids is considered a normal variant?
Which of the following sesamoids is considered a normal variant?
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How many sesamoids are typically found in the human hand?
How many sesamoids are typically found in the human hand?
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Where is a sesamoid located in the thumb?
Where is a sesamoid located in the thumb?
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Which tendon is associated with the most common sesamoid in the thumb?
Which tendon is associated with the most common sesamoid in the thumb?
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What is a mechanical advantage provided by sesamoids?
What is a mechanical advantage provided by sesamoids?
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Which sesamoid is located at the radial side of the index finger MCP joint?
Which sesamoid is located at the radial side of the index finger MCP joint?
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Which of the following statements about sesamoids is true?
Which of the following statements about sesamoids is true?
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What is the function of the capitate bone in the wrist?
What is the function of the capitate bone in the wrist?
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Which carpal bone is located in line with the middle finger?
Which carpal bone is located in line with the middle finger?
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What distinct feature does the hamate bone have?
What distinct feature does the hamate bone have?
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Which mnemonic can help remember the order of the carpal bones?
Which mnemonic can help remember the order of the carpal bones?
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Which of the following statements about the trapezoid bone is true?
Which of the following statements about the trapezoid bone is true?
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How many metacarpals are present in the human hand?
How many metacarpals are present in the human hand?
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Which carpal bone forms part of the anatomical snuff box?
Which carpal bone forms part of the anatomical snuff box?
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What is the anatomical position of the capitate bone?
What is the anatomical position of the capitate bone?
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Study Notes
Ulna, Radius & Hand Bones
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The Ulna and Radius are the two bones of the forearm.
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The Radius is on the lateral (thumb) side of the forearm.
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The Ulna is on the medial (pinky) side of the forearm.
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The Radius helps position the hand.
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Pivoting of the radius allows for pronation and supination movements.
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The Radius is the smaller of the two forearm bones.
- Its proximal end is narrower.
- Its distal end is wider.
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The Ulna is the longer of the two forearm bones.
- Its proximal end is wider.
- Its distal end is narrower.
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The shafts of both bones are triangular in cross-section.
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The Ulna is the medial stabilizing bone of the forearm.
- It remains stationary during pronation/supination.
- Its larger proximal end forms the elbow.
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The Ulna's shaft is triangular.
- It has three borders (anterior/volar, posterior/dorsal, and interosseous).
- It has three surfaces (anterior/volar, posterior/dorsal, and medial).
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The proximal Ulna has these landmarks:
- Olecranon process: fits into the olecranon fossa of the posterior humerus.
- Coronoid process: fits into the coronoid fossa of the humerus.
- Trochlear/semilunar notch: articulates with the trochlea of the humerus.
- Radial notch: articulates with the radial head.
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The Ulna (brachial) tuberosity is the insertion point for the brachialis muscle.
- The supinator crest is inferior to the ulnar tuberosity.
- The supinator muscle attaches at the supinator fossa.
- The interosseous border is a ridge or crest along the sharp lateral edge of the ulnar shaft.
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The distal Ulna is narrower.
- Its rounded head articulates with the ulnar notch of the radius.
- It has a styloid process.
- It has an ulnar collateral ligament.
Radius
- The Radius is located on the thumb side of the forearm.
- It moves during pronation/supination.
- Its proximal end is circular (disc shaped) and covered with hyaline cartilage.
- Its distal end is biconcave, triangular, and covered with hyaline cartilage.
- It articulates with two carpal bones.
- Radius has these landmarks:
- Head
- Neck
- Radial (bicipital) tuberosity (insertion point for biceps muscle)
- Styloid process
- Distal end (lateral side)
- Shaft (triangular shape)
- 3 borders (Anterior, Medial or interosseous, Posterior)
- 3 surfaces (Anterior, Posterior, Lateral)
- The Proximal End of the Radius has these components:
- Head
- Articular Fovea
- Superior surface of radial head
- Deep, concave fossa that articulates with the capitulum of the humerus.
- Circumferential articulation: articulates with radial notch of ulna.
- The Pronator tubercle of the Radius is on the middle of the lateral surface.
- The Interosseous border (ridge,crest) is the sharp medial edge of the radial shaft.
Radius: Distal End
- The Dorsal (Lister's) tubercle is on the back/dorsum of the wrist.
- The styloid process is the insertion point of the brachioradialis and radial collateral ligament
- The ulnar/sigmoid notch is the distal radioulnar joint.
- The groove for extensor pollicis longus muscle, extensor digitorum and extensor indicis muscles, can be found on the radius's distal end.
Carpals:
- The carpals are the short bones of the wrist.
- There are 8 carpals in total.
- They are arranged in two rows.
- The mnemonic "Some Lovers Try Positions That They Can't Handle" can help remember the order. (Lateral to medial, and proximal to distal).
- Scaphoid, Lunate, Triquetrum, Pisiform are in the proximal row.
- Trapezium, Trapezoid, Capitate, Hamate are in the distal row.
Metacarpals
- There are 5 metacarpal bones.
- They are numbered I through V (thumb to pinky).
- Each metacarpal has a base (proximal), shaft/body, and head (distal).
- The metacarpals articulate with the distal row of carpals and the phalanges.
Phalanges
- There are 14 phalanges in total.
- The thumb has 2 phalanges (proximal and distal).
- Other fingers have 3 phalanges (proximal, middle, and distal).
- Each phalanx has a base (proximal), body (intermediate), and head (distal).
Sesamoids
- Sesamoids develop in tendons at the ends of long bones.
- They protect tendons from friction and change the angulation of the tendon for mechanical advantage.
- The patella is a well-known example of a sesamoid.
- The most frequent location for sesamoids in the hand are within the thumb's MCP joint.
- 1-2, in the interphalangeal joint of the thumb..
- 1-2, at radial and ulnar side of index and little finger's MCP joint.
Surface Anatomy (Hand)
- Information about the hand's creases and landmarks for examination of the hand are mentioned.
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Description
Test your knowledge about the anatomy of the forearm bones, including the radius and ulna. This quiz covers their positions, functions, and characteristics. Perfect for students studying anatomy or anyone interested in human body structure.
