CHAPTER 13 Hand147 Precision Grips-cont\'d Grip Tip-to-tip 12. Functional activi
ID: 3515617 • Letter: C
Question
CHAPTER 13 Hand147 Precision Grips-cont'd Grip Tip-to-tip 12. Functional activity analysis: In each chapter on the upper extremit, you be analyzing the activity of placing a plate in a cabinet then removing the plate and placing it on the counter. Perform those tasks and then analyze how the subject in Figures 13-22 and 13-23 performed those tasks. Description Example Tip of the thumb is touched against the tip of another digit or pincer Pad-to-side or Pad of the extended lateral prehension thumb presses an object against the radial side of the index finger Side-to-side Two adjacent fingers are adducted Lumbrical or plate FIGURE 13-22 Starting position of placing a plate in cabinet. MCP joints flex and the PIP and DIP joints extend; thumb opposes the fingers Describe the conditions that permit the extensor muscles of the wrist to produce grasp. 10. FIGURE 13-23 Starting position of placing a plate on counter This tendon action of a muscle is also known as: A. Describe the type of grasp used when the subject holds the plate 11. Hold a piece of paper between your index and middle fingers (or any two adjacent fingers) while your classmate tries to pull the paper out from between your fingers. A. Was it easy or hard to remove the paper? B. Which muscle group(s) is/are maintaining the grasp as the plate is being lowered from the cabinet shelf to the counter? C. Describe the type of muscle contraction being B. which muscles were at work and what were used and why as the plate is being lowered from the cabinet shelf to the counter their actions? C. Damage to which nerve weakens these D. Does the type of grasp change during the muscles? motion of moving the plate from the shelf to the counter and back to the shelf?Explanation / Answer
10.The main role of muscles of the wrist complex is to provide a stable base for hand while permitting positional adjustment that allows for optimal length tension relationship in the long finger muscles .The major contributor of the wrist complex controls length tension relationship in multiarticular hand muscles which in turn allows fine adjustment of grip .The primovers of wrist extension are extensor carpi radialis longus, extensor carpi radialis brevis(ECRB) and extensor carpi ulnaris.Six muscles act secondarily on the wrist and are thumb muscles which are extensor digitorum communis, the extensor indices proprius, extensor digiti minimi, extensor pollicis longus ,brevis and abductor pollicis brevis.
Extensor carpi radialis muscle arrises from the distal third supracondylar ridge of the humerus and adjacent part of the lateral intermuscular septum.Extensor carpi radialis brevis originates from the lateral epicondyle of humerus and the fascia covering common extensor origin.Extensor carpi radialis longus is innervated by radial nerve c6 c7 where it acts as a extensor and abductor at the wrist and midcarpal joints.The extensors have a role not only in providing balance force for flexor muscles but also essential for smooth and controlled opening of hand and release.The fingers wind up to make a fist, the wrist tends to extend especially when force is applied, wrist extensors have marked effect on the long flexor tendons. If this effect of wrist extensor was absent, digital flexion would require the long tendons to move more proximally in their respective with shortening of forehand muscles. Thus wrist extension tends to produce a lengthening effect of the same muscles, which in normal use is almost enough to balance the shortening due to finger flexion.The finger, palm and wrist musculature help in gripping, grasping and making a fist. The main function in gripping is finger flexion which is activated by finger flexors in forearm.
The tendon action of a muscle is called aponeurosis.
11.A. It was easy to remove the paper.
B.The muscles which were at work are palmar interossei, dorsal interossei and the lumbricals, which performed the finger's extensor mechanism. Fibers from some of the interosseiwrap around the proximal phalanges . All three intrinsic groups of muscles pass palmar to the axis of the metacarpophalangeal joints and therefore contribute to flexion there.
C.Damage to Ulnar nerve weakens these muscles.