Module Notes: Bones of the Hand and Wrist

General Bone Count and Small Bones

• The human skeleton contains $206$ bones.
• A significant majority of these are small bones, particularly in the hands and feet.
• Each hand contains numerous metacarpals and phalanges; with $15$ to $19$ of these structures per hand, equating to approximately $40$ per hand and another $40$ in the toes and feet.
• Removing these $80$ bones from the total reduces the count to around $120$ bones.
• The presence of $12$ pairs of ribs further allows for quick reduction in the overall bone count when focusing on specific regions.

Carpal Bones (Wrist)

• There are eight bones in the wrist that students are responsible for knowing.
• These are collectively known as the carpal bones.
• All carpal bones are classified as irregular bones.
• They are arranged in two rows.
• Mnemonic for learning carpal bones: "Straight line to pinky, here comes the thumb."
• Identification Aids:
  • Students may find it helpful to use other mnemonics or learn them visually based on their pattern.
  • In a lab setting, physical identification of individual bones (e.g., from a box) requires knowledge of small physical differences.
  • Pisiform: The easiest one to identify due to its small size and round, pebble-like appearance.
  • Hamate: Features a very distinct "hook of the hamate" that protrudes.

Metacarpals (Hand)

• Students should be able to identify a bone as a metacarpal when seen.
• No numbering of individual metacarpals (i.e., metacarpal $1$, $2$, $3$, etc.) is required.

Phalanges (Fingers)

• Students should be able to identify bones as phalanges.
• No numbering of individual phalanges is required (e.g., knowing it's phalanx $1$, $2$, or $3$ is not necessary).
• Proximal vs. Distal Identification:
  • Students need to differentiate between proximal and distal phalanges.
  • Distal phalanges are characterized by having small tips at their ends.
  • The thumb is unique, possessing only two phalanges (a proximal and a distal phalanx), lacking the third middle phalanx found in other digits.

Learning Resources and Strategy

• A new PowerPoint presentation titled "Analogies and Mnemonics of the Skeletal System" will be made available to provide visual guides and analogies for learning these bones.
• The focus for assessment regarding hand bones will primarily be on the eight carpal bones, with less emphasis on the individual bones of the fingers.

Carpal Tunnel Syndrome

• This condition is commonly known and involves a fluid buildup in the wrist region.
• This fluid buildup creates pressure on the nerves and blood vessels passing through the carpal tunnel.
• The median nerve is particularly susceptible to this pressure.
• Symptoms include tingling, numbness, and considerable pain in the hand.
• The mechanism involves the pressure exerted within the confined gap area between the bones in the wrist.