Friday, 7 December 2018

Bone surface markings

Most bones have grooves, indentations and protrusions. These are known as surface markings and are necessary structures for the musculoskeletal system. Not only do they help increase the stability of joints, they also provide muscle attachment sites.

The two categories of surface markings are depressions and processes.

Depressions

Depressions are flattened or indented parts of the bone. A common one is called a fossa, such as in the back of the scapula (shoulder blade) where the infraspinatus muscle attaches. Another one is a sulcus, which is a groove, such as that between the processes at the top of the humerus, to which the long-head of the biceps tendon runs through.

Processes

Processes are projections that protrude from a bone, which allow muscles, tendons and ligaments to attach. The most common forms of processes are:

  • Condyle: Prime example being found at the knee joint where they consist of the inner and outer portions of the top of the hip and bottom of the femur.
  • Epicondyle: Prime example being found at the elbow joint where they consist of the inner and outer portions of the bottom of the humerus.
  • Process: Examples of processes include the acromion and coracoid of the collarbone. The vertabrae also contain processes.
  • Trochanters: The bony projections at the top of the femur, with the great trochanter known as the hip-bone as it connects to the hip. The trochanters allow for the attachment of the hip musculature.
  • Tubercles: Also known as tuberosities, the prime examples are the tubercles at the top of the humerus that help form the shoulder joint.
Surface markings of the humerus bone
Picture of the humerus bone depicting some of its tubercle's (tuberosity), epicondyle's and fossa's. (click to enlarge). Image from Wikipedia.

Articles within this series

Lyle Richardson,
Gym Pal - Unlock Your Potential

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