The digits are named in a similar fashion to the metacarpals, moving lateral to medial, and starting at the thumb. With the exception of the thumb, each digit contains a proximal, intermediate, and distal phalange; the thumb lacks an intermediate phalange.
The length of the phalanges decreases distally. Human hand bones : Fingers are made up of proximal, intermediate, and distal phalanges. The thumb lacks an intermediate phalange. Learning Objectives Describe the types of bones in the hand.
Key Points There are eight carpal bones in each wrist. There are five metacarpal bones in each hand. There are proximal, intermediate, and distal phalanges in each digit except for the thumb, which lacks an intermediate phalange.
Key Terms metacarpal : Any of the bones of the palm. Carpals The eight, irregularly shaped carpals are the most proximal bones of the hand. Metacarpals The hand contains five metacarpal bones that articulate proximally with the carpals and distally with the proximal phalanges.
Free E-newsletter Subscribe to Housecall Our general interest e-newsletter keeps you up to date on a wide variety of health topics. Sign up now. Mayo Clinic Press Check out these best-sellers and special offers on books and newsletters from Mayo Clinic.
IMG Home Wrist bones. Legal Conditions and Terms Any use of this site constitutes your agreement to the Terms and Conditions and Privacy Policy linked below. Advertising Mayo Clinic is a nonprofit organization and proceeds from Web advertising help support our mission. Advertising and sponsorship policy Advertising and sponsorship opportunities. Structurally, the femur is a long bone, meaning its length is greater than its width, while the patella, a sesamoid bone, is small and round.
Functionally, the femur acts as a lever, while the patella protects the patellar tendon from compressive forces. Skip to content Bone Tissue and the Skeletal System.
Learning Objectives By the end of this section, you will be able to: Classify bones according to their shapes Describe the function of each category of bones. Short Bones A short bone is one that is cube-like in shape, being approximately equal in length, width, and thickness. Irregular Bones An irregular bone is one that does not have any easily characterized shape and therefore does not fit any other classification. Sesamoid Bones A sesamoid bone is a small, round bone that, as the name suggests, is shaped like a sesame seed.
Bone Classifications Bone classification Features Function s Examples Long Cylinder-like shape, longer than it is wide Leverage Femur, tibia, fibula, metatarsals, humerus, ulna, radius, metacarpals, phalanges Short Cube-like shape, approximately equal in length, width, and thickness Provide stability, support, while allowing for some motion Carpals, tarsals Flat Thin and curved Points of attachment for muscles; protectors of internal organs Sternum, ribs, scapulae, cranial bones Irregular Complex shape Protect internal organs Vertebrae, facial bones Sesamoid Small and round; embedded in tendons Protect tendons from compressive forces Patellae.
Chapter Review Bones can be classified according to their shapes. Which category of bone is among the most numerous in the skeleton? Critical Thinking Questions What are the structural and functional differences between a tarsal and a metatarsal? Glossary flat bone thin and curved bone; serves as a point of attachment for muscles and protects internal organs irregular bone bone of complex shape; protects internal organs from compressive forces long bone cylinder-shaped bone that is longer than it is wide; functions as a lever sesamoid bone small, round bone embedded in a tendon; protects the tendon from compressive forces short bone cube-shaped bone that is approximately equal in length, width, and thickness; provides limited motion.
Previous: The Functions of the Skeletal System. Next: Bone Structure.
0コメント