Foundations of Occupation: Kinesiology in Daily Life(week 9)

80 USC Chan Division of Occupational Science and Occupational Therapy

Foundations of Occupation: Kinesiology in Daily Life
Learning Objectives

At the end of the lecture and ELL, the learner will be able to:

  • Identify the bones and joints of the hand.

  • Describe the motions that take place at each joint in the hand and the muscles responsible for the motions.

    • Identify positions as well as motions at each joint.

  • Identify the structures that support and stabilize the metacarpophalangeal (MP) joints of the hand, including the:

    • Capsule

    • Ligaments (generally)

    • Volar plate

    • Discuss in which positions they are more/less effective.

  • Describe the architecture of the hand (arches and variations in range of motion radially to ulnarly) and how it contributes to function.

  • Describe the motions of the thumb.

  • List the extrinsic muscles of the fingers and thumb and describe their functions.

  • List the intrinsic muscles of the thumb and describe their functions.

  • View pictures or video of an activity and determine the motion(s) occurring in the hand and the muscles responsible for the action/position.

Overview

  • Wrist Review and Wrist Lab

  • Hand Anatomy: Bones, Joints, and Accessory Structures

  • Arches of the Hand

  • Motions of the Fingers and Thumb

  • Extrinsic Finger Muscles

Wrist Review
Review: The Carpal Bones

  • Scaphoid

  • Lunate

  • Triquetrum

  • Pisiform

  • Trapezium

  • Trapezoid

  • Capitate

  • Hamate

Review: Carpal Kinematics

  • Proximal row of carpals rolls in the direction of the hand movement and slides in the opposite direction (convex-on-concave; open chain movement).

  • In general:

    • Axis for flexion begins at the proximal carpal row.

    • Axis for extension begins at the distal carpal row.

Wrist Flexion & Extension

  • Positions: Neutral, Extended, Flexed

Ulnar and Radial Deviation

  • Definitions:

    • Radial Deviation (Wrist ABduction)

    • Ulnar Deviation (Wrist ADduction)

Directional Terms

  • Anterior (palmar/volar)

  • Posterior (dorsal)

Review: Wrist Muscles

  • Finger and thumb muscles also cross the wrist and may assist with wrist movement:

    • Flexor Carpi Ulnaris (FCU): Exerts greatest tension.

    • Extensor Carpi Radialis Brevis (ECRB): More centrally located, active during grasp-and-release activities.

    • Extensor Carpi Radialis Longus (ECRL): Increased activity during forceful finger flexion motions.

  • Flexors:

    • FCU

    • FCR

    • PL (Palmaris Longus)

  • Extensors:

    • ECU

    • ECRL

    • ECRB

Hand Anatomy: Bones, Joints, and Accessory Structures
Bones of the Hand

  • Phalanges:

    • Distal Phalanx

    • Middle Phalanx

    • Proximal Phalanx

  • Metacarpals: 1 to 5 (Dorsal View of the Right Hand)

The Joints of the Hand

  • Carpometacarpal Joint (CMC):

    • Articulation between distal carpal row and bases of metacarpal bones.

  • Metacarpophalangeal Joint (MCP or MP):

    • Articulation between the metacarpal and its phalanx.

  • Interphalangeal Joint (IP):

    • Articulations between the phalanges of the digits:

    • On digits 2-5, identified as either proximal (PIP) or distal (DIP).

Carpometacarpal Joints (CMC)

  • Metacarpals articulate with carpal bones, and with each other (adjacent) to some degree:

    • Digits 2 to 4: slight gliding motion (plane, synovial).

    • Digit 5: slight gliding motion and some fifth finger opposition (condyloid).

  • Thumb Carpometacarpal (CMC):

    • Articulation between the trapezium and base of the 1st metacarpal (true saddle joint).

  • CMC Stability:

    • Supported by strong transverse ligaments and weaker longitudinal ligaments volarly and dorsally.

Available Motion in CMC Joints

  • Essentially no motion at 2nd and 3rd CMCs.

  • A little motion at 1st and 4th/5th CMCs.

  • Thus, metacarpals (hand) move with distal carpal row.

  • Plane joints allow multiaxial movements; however, CMCs have very limited movement due to tight fit together and surrounding structures (e.g., robust ligamentous support).

Thumb CMC

  • Comparison: Like 2 Pringles stacked together, allowing movement in two planes.

  • Increased ROM: As move to ulnar side, helps to form hand around object.

Metacarpophalangeal Joints (MP or MCP)

  • Articulation between:

    • Convex head of metacarpal bones and concave base of proximal phalanges.

  • MCP/MCPs in digits 2-5:

    • Condyloid joints with two degrees of freedom:

    • Flexion/Extension

    • Abduction/Adduction

  • MCP of thumb operates more like an IP joint.

    • Somewhat of a condyloid joint functions like a hinge joint due to limited abduction/adduction; one degree of freedom.

    • Thumb CMC functions like a freer version of MCP of other digits.

MCP Stability

  • Provided by:

    • Volar Plate (palmar)

    • Collateral Ligaments

    • Transverse Metacarpal Ligament

  • Joint capsule is not considered to contribute to joint stability, except when MCPs are in the position of flexion.

Interphalangeal Joints (IP)

  • Comprised of:

    • Proximal head of phalanx

    • Base of adjacent distal phalanx

  • True synovial hinge joints (1 degree of freedom–flexion/extension):

    • Most PIPs have >90° of flexion.

    • Thumb IP is identical to DIPs of digits 2-5.

Volar Plate

  • Fibrocartilaginous structure which restricts hyperextension at MCPs, PIPs, and DIPs.

  • Primary restraint against dorsal subluxation or dislocation.

  • Necessary due to the joint structure (not a deep joint like the shoulder).

  • Each plate runs from the distal end of one bone to the proximal end of the adjacent bone at MCPs, PIPs, and DIPs.

Ligamentous Support

  • 5th MC, 2nd MC, 1st MC.

  • Functional components include:

    • FDS/FDP tendons

    • Annular pulleys

    • Digital tendon sheath

    • Transverse metacarpal ligament

    • Ulnar bursa

    • Flexor retinaculum

    • Radial bursa.

Transverse Metacarpal Ligament

  • Tethers heads of metacarpals, holding heads together.

Annular Pulleys

  • Channel ligaments to maintain ideal tendon positioning while allowing tendon movement.

  • Example: A3 pulley (ruptured) leads to bowstring phenomenon.

Collateral Ligaments

  • One ulnar and one radial at each MCPs and IPs.

  • Limit side-to-side movement, resisting lateral impact forces.

  • Each side has two branches:

    • Proper: bone to bone (e.g., metacarpal to proximal phalanx).

    • Accessory: bone to volar plate (e.g., metacarpal to corresponding volar plate).

Joint Capsule

  • Contributes to the overall stability in conjunction with collateral ligaments and other structures.

Palmar Arch System

  • Functionality:

    • Allows palm and digits to optimally conform to shapes of objects.

    • Increased surface contact enhances stability of grasp and sensory information for skilled interaction.

  • Arches:

    • Transverse Arches: run across palm at both distal and proximal ends.

    • Longitudinal Palmar Arch: runs the length of the palm, vertically, parallel to metacarpals.

    • Oblique Palmar Arch: runs from the thumb across palm diagonally to base of the 5th digit.

  • Hollowing of palm accompanies finger flexion, while flattening accompanies finger extension.

  • Muscles crossing over CMC joints contribute to hollowing/flattening of palmar arches and palm cupping.

Motions of the Digits and Thumb

MCP Motions

  • Base of proximal phalanx glides and rolls anteriorly during flexion (same direction as the movement) and glides and rolls posteriorly during extension (concave-on-convex).

  • Abduction: 2nd, 4th, and 5th fingers move away from 3rd finger.

  • Adduction: 2nd, 4th, and 5th fingers move towards the 3rd finger.

IP Motions

  • Only movements observed are flexion and extension due to hinge joint classification.

Thumb Motion: CMC Joint

  • Extended: with forearm supinated, extend thumb to touch table.

  • Flexed: thumb sweeps the palm cleanly with contact.

  • Neutral: when thumbs align with 2nd metacarpal and rest on palm (concave-on-convex movement).

Thumb Motion: Abduction/Adduction

  • Abduction and Adduction occur with the forearm in neutral.

  • Adduction brings thumb in contact with palm, abduction extends outward to create an 'L' shape.

  • Movements occur in the sagittal plane around “x” axis (convex-on-concave).

Thumb Motion: Opposition/Reposition

  • Opposition: Movement of thumb from palm to other digits so pads touch.

  • Defined as placing the palmar surface of the tip of the thumb in contact with the palmar surface of the tips of other fingers.

Summary of Joints of the Hands

Adapted from Lippert (2016), Table 13-1, p. 199:

  • Classification and Movement:

    • CMC joints (digits 2-5): Plane, Gliding/Sliding, Nonaxial.

    • MCP joint (digit 1): Hinge, Flexion/Extension, Uniaxial.

    • IP joint (digit 1): Hinge, Flexion/Extension, Uniaxial.

    • PIP joints (digits 2-5): Hinge, Flexion/Extension, Uniaxial.

    • DIP joints (digits 2-5): Hinge, Flexion/Extension, Uniaxial.

    • CMC joint (digit 1): Saddle, Flexion/Extension, Abduction/Adduction, Biaxial.

    • MCP joints (digits 2-5): Condyloid, Flexion/Extension, Abduction/Adduction, Biaxial.

Muscles of the Fingers - Extrinsics

  • Extrinsic Finger Muscles:

    • Flexor digitorum superficialis

    • Flexor digitorum profundus

    • Extensor digitorum communis

    • Extensor digiti minimi

    • Extensor indicis

Extrinsic Finger Flexors

  • Flexor digitorum superficialis (FDS):

    • Origin: common flexor tendon from medial epicondyle of humerus.

    • Insertion: sides of middle phalanges of digits 2 through 5.

    • Action: prime mover for MCP and PIP flexion of all fingers; assists with wrist flexion.

  • Flexor digitorum profundus (FDP):

    • Origin: anterior and medial surfaces of the ulna.

    • Insertion: distal phalanx of fingers.

    • Action: prime mover for flexion of MCPs, PIPs, and DIPs of fingers; assists with wrist flexion.

    • Note: FDP is the only muscle that flexes the DIP joint.

Review: Palmar Accessory Structures

  • Consists of flexor retinaculum, ligaments, bursae, and tendon sheaths that tether long flexor tendons to hand while permitting friction-free excursion.

    • Key Components:

    • Ulnar bursa

    • Radial bursa

    • Digital tendon sheaths

    • Flexor retinaculum and annular ligaments prevent bowstringing.

Extrinsic Finger Extensors

  • Extensor digitorum communis (EDC):

    • Origin: common extensor tendon on lateral epicondyle of humerus.

    • Insertion: base of 2nd – 5th middle & distal phalanges via extensor hood.

    • Action: extends all 3 joints of the fingers.

  • Extensor digiti minimi (EDM):

    • Origin: common extensor tendon on lateral epicondyle of humerus.

    • Insertion: base of 5th distal phalanx.

    • Action: extends all 3 joints of the 5th digit.

  • Extensor indicis (EI):

    • Origin: distal ulna.

    • Insertion: Base of 2nd distal phalanx.

    • Action: extends 3 joints of the second digit.

Conclusion

  • EDC, EDM, and EI serve as prime movers for extension of MCP joints and assist in wrist extension.

  • The extensor retinaculum holds extensor tendons close to the wrist, permitting friction-free excursion during extension.

Foundations of Occupation: Kinesiology in Daily Life

Learning Objectives

At the end of the lecture and ELL, the learner will be able to:

  • Identify the bones and joints of the hand.

  • Describe the motions that take place at each joint in the hand and the muscles responsible for the motions.

  • Identify positions as well as motions at each joint.

  • Identify the structures that support and stabilize the metacarpophalangeal (MP) joints of the hand, including the:

    • Capsule

    • Ligaments (generally)

    • Volar plate

    • Discuss in which positions they are more/less effective.

  • Describe the architecture of the hand (arches and variations in range of motion radially to ulnarly) and how it contributes to function.

  • Describe the motions of the thumb.

  • List the extrinsic muscles of the fingers and thumb and describe their functions.

  • List the intrinsic muscles of the thumb and describe their functions.

  • View pictures or video of an activity and determine the motion(s) occurring in the hand and the muscles responsible for the action/position.

Overview

  • Wrist Review and Wrist Lab

  • Hand Anatomy: Bones, Joints, and Accessory Structures

  • Arches of the Hand

  • Motions of the Fingers and Thumb

  • Extrinsic Finger Muscles

Wrist Review

Review: The Carpal Bones

  • Scaphoid

  • Lunate

  • Triquetrum

  • Pisiform

  • Trapezium

  • Trapezoid

  • Capitate

  • Hamate

Review: Carpal Kinematics

  • Proximal row of carpals rolls in the direction of the hand movement and slides in the opposite direction (convex-on-concave; open chain movement).

  • In general:

    • Axis for flexion begins at the proximal carpal row.

    • Axis for extension begins at the distal carpal row.

Wrist Flexion & Extension

  • Positions: Neutral, Extended, Flexed

Ulnar and Radial Deviation

  • Definitions:

    • Radial Deviation (Wrist ABduction)

    • Ulnar Deviation (Wrist ADduction)

Directional Terms

  • Anterior (palmar/volar)

  • Posterior (dorsal)

Review: Wrist Muscles

  • Finger and thumb muscles also cross the wrist and may assist with wrist movement:

    • Flexor Carpi Ulnaris (FCU): Exerts greatest tension, contributing significantly to wrist flexion and ulnar deviation.

    • Extensor Carpi Radialis Brevis (ECRB): More centrally located, active during grasp-and-release activities. A prime mover for wrist extension.

    • Extensor Carpi Radialis Longus (ECRL): Increased activity during forceful finger flexion motions; contributes to wrist extension and radial deviation.

  • Flexors:

    • FCU

    • FCR (Flexor Carpi Radialis)

    • PL (Palmaris Longus)

  • Extensors:

    • ECU (Extensor Carpi Ulnaris)

    • ECRL

    • ECRB

Hand Anatomy: Bones, Joints, and Accessory Structures

Bones of the Hand

  • Phalanges: The long bones of the digits. Each finger (digits 2-5) has a distal phalanx, a middle phalanx, and a proximal phalanx. The thumb (digit 1) has only a distal and a proximal phalanx.

    • Distal Phalanx (P3)

    • Middle Phalanx (P2)

    • Proximal Phalanx (P1)

  • Metacarpals: Five long bones (1 to 5) that form the palm of the hand. They articulate proximally with the carpal bones and distally with the proximal phalanges.

    • Metacarpals 1-5 (Dorsal View of the Right Hand)

The Joints of the Hand

  • Carpometacarpal Joint (CMC): Articulation between the distal carpal row and the bases of the metacarpal bones.

  • Metacarpophalangeal Joint (MCP or MP): Articulation between the metacarpal head and the base of its corresponding proximal phalanx.

  • Interphalangeal Joint (IP): Articulations between the phalanges of the digits.

    • On digits 2-5, identified as either proximal (PIP) or distal (DIP).

    • The thumb (digit 1) has only one IP joint.

Carpometacarpal Joints (CMC)

  • Metacarpals articulate with carpal bones, and with each other (adjacent) to some degree.

    • Digits 2 to 4: Exhibit slight gliding motion, classified as plane synovial joints with minimal movement. The 2nd CMC connects to the trapezoid, the 3rd to the capitate, forming the rigid central pillar of the hand.

    • Digit 5: Shows slight gliding motion and some fifth finger opposition, functioning as a condyloid joint, allowing more mobility for grasping.

  • Thumb Carpometacarpal (CMC): Articulation between the trapezium and the base of the 1st metacarpal. This is a true saddle joint, providing significant mobility crucial for thumb function.

    • It allows two degrees of freedom: flexion/extension and abduction/adduction, which combine to produce opposition.

  • CMC Stability:

    • Supported by strong transverse intermetacarpal ligaments and weaker longitudinal ligaments volarly and dorsally.

    • The deep transverse metacarpal ligament connects the heads of metacarpals 2-5, stabilizing them.

Available Motion in CMC Joints

  • Essentially no motion at the 2nd and 3rd CMCs, which form a stable central pillar for the hand's functional axis.

  • A little motion at the 1st (thumb) and 4th/5th CMCs, contributing to the hand's ability to conform to objects.

  • Thus, the metacarpals (hand) move largely with the distal carpal row, with slight mobility on the radial and ulnar sides.

  • Plane joints typically allow multiaxial movements; however, CMCs have very limited movement due to a tight fit and robust surrounding ligamentous support, except for the highly mobile thumb CMC.

Thumb CMC

  • Comparison: Like 2 Pringles stacked together, its unique saddle shape allows complex movements in two primary planes (flexion/extension and abduction/adduction), leading to circumduction and opposition.

  • Increased ROM: Movement on the ulnar side (4th and 5th CMCs) facilitates the formation of a deeper palmar arch (cupping) to conform the hand around larger objects, enhancing grip stability.

Metacarpophalangeal Joints (MP or MCP)

  • Articulation between:

    • The convex head of the metacarpal bones and the concave base of the proximal phalanges.

  • MCPs in digits 2-5:

    • Condyloid joints with two degrees of freedom:

      • Flexion/Extension: The primary motion.

      • Abduction/Adduction: Movement away from/towards the 3rd digit (axial line of the hand).

  • MCP of the thumb (digit 1):

    • Functions primarily like a hinge joint due to robust collateral ligaments that limit abduction/adduction.

    • It primarily allows one degree of freedom: flexion/extension (up to 50°-70° of flexion), similar to an IP joint.

MCP Stability

  • Provided by:

    • Volar Plate (Palmar): A thick fibrocartilaginous plate on the palmar aspect, which prevents hyperextension and reinforces the joint capsule.

    • Collateral Ligaments: Strong fibrous bands on the radial and ulnar sides of each joint. These ligaments are taut in flexion, providing maximal side-to-side stability, and relatively lax in extension, allowing for some accessory movement like abduction/adduction in digits 2-5.

    • Transverse Metacarpal Ligament: Connects the heads of metacarpals 2 to 5, preventing excessive splaying of the metacarpals.

  • The joint capsule alone is not considered to contribute significantly to joint stability, except when the MCPs are in the position of flexion, where it becomes taut in conjunction with the collateral ligaments.

Interphalangeal Joints (IP)

  • Comprised of:

    • The convex proximal head of one phalanx and the concave base of the adjacent distal phalanx.

  • True synovial hinge joints (1 degree of freedom – flexion/extension):

    • Most PIPs have >90° of flexion, crucial for finger curling into a fist.

    • DIPs generally have 70°-90° of flexion.

    • The thumb IP is structurally and functionally identical to the DIPs of digits 2-5, allowing only flexion and extension.

Volar Plate

  • A dense, fibrocartilaginous structure that reinforces the joint capsule on the palmar side of MCP, PIP, and DIP joints.

  • Its primary function is to restrict hyperextension and prevent dorsal subluxation or dislocation by providing a strong static restraint.

  • It is essential due to the joint structure not being a deep socket, like the shoulder.

  • Each plate runs from the distal end of one bone (e.g., metacarpal) to the proximal end of the adjacent bone (e.g., proximal phalanx).

Ligamentous Support

  • The hand and wrist are extensively supported by a network of ligaments, including:

    • Carpometacarpal ligaments: Connect carpal bones to metacarpals.

    • Intermetacarpal ligaments: Bind adjacent metacarpals.

    • Collateral ligaments: Provide medial and lateral stability to MCP and IP joints.

    • Volar (palmar) ligaments: Reinforce the palmar aspect of joints.

  • Functional components listed previously (FDS/FDP tendons, annular pulleys, digital tendon sheath, transverse metacarpal ligament, ulnar bursa, flexor retinaculum, radial bursa) are integral to tendon mechanics and overall function, not strictly joint-supporting ligaments.

Transverse Metacarpal Ligament

  • A strong ligament that tethers the heads of metacarpals 2-5 together, preventing excessive spreading (splaying) of the metacarpal heads, especially during grasping actions.

Annular Pulleys

  • These are fibrous tunnels or sheaths that hold the flexor tendons close to the phalanges.

  • They prevent

An