Hand (Thumb and Fangers) Flashcards
Contrast the CMC joints 2 & 3 with 4 & 5 . What is the functional significance of the more mobile ulnar CMC joints?
Base of hand meeting with the wrist. Pg 250 fig 8-10
2&3 are essentially immobile or stiff and rigid.
4&5 are much more mobile
When grasping something, the thumb and 4&5 wrap around an object to create more contact and get a better grip.
What type of joint structure is the thumb CMC joint? Name the primary motions that occur at this joint, give the degrees of freedom, arthrokinematics, and planes of motion as well as the direction of joint axes of each primary motion of the thumb
Thumb is saddle joint, just like the SC joint.
2 Degrees of freedom.
Flex across palm or frontal plane/Ext,
Abduction moves perpendicular to palm. Sagittal plane for abd/add.
Flex/Ext concave metacarpal on convex carpal. Roll and slide ulnarly. Frontal plane. Anterior/Posterior axis
Abd/Add medial/Lateral axis. Convex on concave base of metacarpal (pg 253 fig 8-16). Roll is anterior. Slide is posterior.
What is opposition? reposition? how is each derived?
Opp…A type of functional circumduction. Thumb crossing the palm of the hand in a circumducting motion to reach the CMP 5 joint. 1. Abd, flex, and some medial rotation to midline of the hand.
Reposition… Return thumb to neutral.
Extend, adduct, and lateral rotation.
Name the osteokinematic motions, degrees of freedom and planes of motion for “all” MCP joints. MCP or MP joints.
All flex/ext, and abd/add.
2 degrees of freedom
Sagittal/Frontal
(Thumb is different)–Frontal/Sagittal.
Identify the location and direction of axes of rotation for each motion of MCP joints.
Metacarpals are convex in both planes. Axis of rotation and direction of flex/ext 2-5 is medial-lateral through metacarpal head.
Axis of rotation and direction of abd/add is anterior/posterior through metacarpal head.
Describe the location, composition and shape of the Palmar or Volar Plate at the MCP joints 2-5 and explain its primary function.
Page 256. They are on the anterior side of MCP, PIP, and DIP. Fribrocartilage structure. Commonly injured. Long skinny triangle shape. Distal is thicker and proximal is thinner. Functions to protect and strengthen the MCP joint by acting like ligaments and limit extension.
Write out the arthrokinematics of MCP joints for the osteokinematic motions. Note the difference in mobility at the MCp joints in neutral vs 90 degrees of flexion. What is/are the concept(s) we are relating when nothing this difference?
Flex/Ext concave on convex. Roll and slide together.
Abd/Add concave on convex. roll and slide together.
Radially and Ulnarly (specify the finger first).
Neutral is open-packed. 90 degrees is close-packed.
Identify the motions, degrees of freedom, plane of motion and axis of rotation location/direction for the IP joints.
Finger axis-medial/lateral. Thumb axis-anterior/posterior.
Flex/Ext only for PIP and DIP. Thumb IP.
1 degree of freedom.
Sagittal plane. Frontal plane (thumb).
Medial/lateral axis of PIP is distal end of proximal phalanx.
Medial/lateral axis of DIP is distal end of middle phalanx.
Identify the functional position of the hand. (pg 261)
Why do we need to know this position?
What is the exception to using this position?
The position used for splinting the hand to preserve the functional position of the hand. It is a neutral position from which all other motions come from. A natural resting position of the hand.
A little wrist extension, MCP, PIP, and DIP are at slight flexion. Thumb is slightly flexed.
Casts are an exception because they are isolating the bone.
How do the concepts of active insufficency and passive insufficency relate to the function of the finger flexors and extensors?
Active Insufficiency–Too short. A muscle is too short. Contracted too short.
Passive Insufficiency–Too long. A muscle is too long. Stretched out too long.
Muscles in the fingers cross multiple joints. If one joint makes the muscle too short or too long, the length-tension relationships further distal are disrupted and less efficient.
Name the additional structure involved in aiding the FDS/FDP’s function in flexing IP joints of digits 2-5. What would be the effect on these tendons without these additional structures? What would be the negative implication of the joints without these additional structures?
Annular pulleys and cruciate pulleys. Non-contractile tissues, act like ligaments because they hold tendons to the bone. Pg. 266 fig 8-36. As the flexor digitorum superficialis flexes, the tendons act as a conduit to keep the tendons really close to the finger bones to maximize efficieny. pg 292 fig 8-64.
If one of the ligaments breaks, the result is a decrease in a ROM. There are diseases that damage tissue and weaken ligaments in the hand Rheumatoid Arthritis causes ulnar drift because MCP joints are weakened.
What potential joint motion(s) [of the finger/s, not at the wrist] occur for a given finger as a result of contraction of the extrinsic finger extensor musculature (EDC)? Explain your response.
Extensor Digitorum can only extend to MCP joints. Other muscles have to work synergistically to exend the rest of the finger. While the ED attaches to the hood of the finger, it does not have the ability to extend the PIP and DIP.
What action do each of the EPL. EPB, APL have on thumb CMC, MCP, and IP joints? What potential action(s) might these muscles have at the wrist and how is this/are these potential action(s) controlled to allow isolation of thumb function/motion?
pg 270 fig 8-42
EPL – at CMC extension (w/ some lateral rotation) and potential adduction. MCP and IP extend.
EPB – CMC and CMP extend. Does not abduct because it crosses the axis where abduction would occur. Stabilizes that particular joint.
APL – CMC extend and abduct.
The wrist wants to radial deviate. We Need wrist ulnar deviators to counteract just a little bit to counter act radial deviation.
Describe how the primary function of the thenar eminence muscles is accomplished and how the common function of the hypothenar muscles is accomplished as well.
Pg 272, Fig 8-44
The thenar eminence muscles produce varying amounts of opposition for fine/gross motor control of grasping. They do this based on their line of pull relative to the axis of rotation of the bone.
Hypothenar muscles cup the palm or deepen the transverse arch of the palm to deepen the ability/contact to grasp. This is done by their line of pull relative to the axis of rotation of the bone.
Considering the interossei and lumbricals together as hand intrinsics, identify and describe where the line of pull is in relationship to the axes of rotation of the MCP, PIP, and DIP joints.
pg 268 fig 8-40 Extensor expansion consists of the hood and bands.
Pg 27 fig 8-48. In relation to the MCP joint, Lumbricals are anterior–flexion. The lumbricals also pull on the extensor expansion. It pull the PIP and DIP joints posteriorly to the axis of rotation–extension.
The interossei and others insert into the hood and they will always want to flex at the MCP.
