Musculoskeletal Introduction
Table of Contents

Terms of Movement:

- flexion: bending or decreasing the angle anterior or posterior between bones or parts of the body
- extension: straightening of a flexed part of joint and placing the body back to anatomic position
- abduction: moving apart or away laterally from the median plane
- adduction: moving together or toward medially the median plane
- elevation: lifting, raising or moving a part superiorly, e.g. shrugging of shoulder
- depression: letting down, lowering or moving a part inferiorly
- protraction: movement anteriorly, e.g. shoulder forward
- retraction: movement posteriorly
- rotation: turning or revolving a part of the body around its long axis either medially or laterally
- circumduction: circular motion around a pivot joint that require a successive movement of flexion, abduction, extension and adduction.
- Supination: rotation of the radius around its long axis so that the palm of the hand faces anteriorly
- Pronation: rotation of the radius around its long axis so that the palm of the hand faces posteriorly
- Opposition: the thumb pad is brought across to a finger pad
- Reposition: the thumb in opposition is brought back to the anatomical position
 Dermatomes: area of skin supplied by cutaneous branches from predominately one single spinal nerve.
 Myotomes: all muscles derived from one somite and innervated by one segment spinal nerve. But a muscle can have more than 1 nerve innervating it and cutting off nerve will weak but not completely stop as it may have alternative.
- Hip: flexion is L2, L3 and extension is L4, L5
- Knee: extension is L3, L4 and flexion is L5, S1
- Ankle: dorsiflexion is L4, L5 and plantarflexion is S1, S2
- Toes: extension is L5, S1 and flexion is S2, S3 / inversion is L4, eversion is L5, S1
 Opposing muscles are usually supplied by subsequent levels of spinal nerves
 The neurovascular plane of the body wall exists between the inner transverse abdominis, and the middle internal oblique of the three muscles layers (other being the superficial external oblique). Both the segmental nerve and the segmental artery passes through this plane and where they cross, segmental nerve is more superficial. The nerve enters the rectus abdominis from behind the epigastric artery while the artery ends in flank muscles.
 Hilton’s Law:
- Nerve sends twig to the joint which muscles moves and another to the skin over the joints.

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