Chapter 13 Hand

Power grips

(isometric contractions) used when object needs to be held forcefully. ex- holding a hammer or doorknob.

Precision grips

(precision prehension) used for manipulating objects using finer movements. Ex- holding a pen or threading need.

Side-to-side grip

* Similar to pad-to-side grip * Requires adduction of two fingers --Usually the index or middle fingers * Weak grip --Does not require much precision --Can be used in the absence of the thumb * Example: --Holding a cigarette or pencil

Smith's fracture

A fracture of distal radius secondary to fall on back of hand.

Accessory Movement

A movement that accompanies the active movement and is essential to normal motion.

CMC Thumb

Allows more mobility then the CMC joints of the other four fingers, yet it also provides as much stability.

pad-to-side grip

Also called lateral prehension has the pad of the extended thumb pressing an object against the radial side of the index finger. Example-holding a key.

Extensor expansion ligament

Also called the extensor hood is a. small triangular, flat aponeurosis covering the dorsum and sides of the proximal phalanx of each finger. Covers the head of the metacarpal and keeps extensor tendon in midline. Attachment for extensor digitorum tendon proximally. Attachment for lumbricals and interossei at distal PIP joint. The extensor hood mechanism is where the extrinsic tendons and intrinsic tendons merge to control PIP and MCP motions.

Longitudial arch

Begins at the wrist and runs the length of the metacarpal and phalanges for each digit. It is perpendicular to the other twp arches. These arches contribute to the function of various GRASPS.

What are CMC joints of the 2nd & 5th digits?

Classified as a nonaxial, plane-shaped synovial joints that provide slight gliding motion. They provide more stability than mobility. The trapeziod articulates with the base of the second metacarpal, the capitate with the base of the third metacarpal, and the hamate with the bases of the fourth and fifth metacarpals. the second and third CMC joints have very little mobility. The fourth CMC joint allows slightly more motion. The fifith CMC joint is the most mobile of the first fingers because of its more condyloid shape, which allows for small amounts of fifth finger opposition.

Thumb joint motions-->CMC joint

Does the following motions: Flexion/Extension; Abduction/Adduction; Oppostion/ Reposition. Occurs in Sagittal Plan; Frontal Axis.

Arthrokinematics

During flexion and extension, the concave base of the first metacarpal glides in the same direction as the distalk end of the metacarpal (concave-on-convex articulation). When flexion occurs, the base of the metacarpal glides medially. During extension the base glides laterally, along with lateral movement of the distal metacarpal. During abduction and adduction (sagittal plane motion) occurs, the convex base of the first metacarpal glides on the concave trapezium in the opposite direction from the distal end of the metacarpal. During abduction, the distal end of the metacarpal moves anteriorly while the base of the metacarpal glides posteriorly, whereas adduction causes posterior movement of the distal end of the metacarpal with an anterior glide of the base.

Thumb motions

Flexion and Extension occur in the frontal plan ( a plane parallel to the palm). Abduction/ adduction occur in the sagittal plane (a plane perpendicular to the palm). Oppostion is a combination of Flexion and abduction in which the tips of the first and fifth digits move toward one another, with the "built-in" accessory motion of rotation. Reposition, using a combination of extension, adduction and "rotation", is the return to anatomical position.

Thumb joint motions-->MCP joint

Flexion/Extension ; occurs in the Frontal Plan; Sagittal Axis.

Thumb joint motions-->IP joint

Flexion/Extension; occurs in the Frontal plane; Sagittal Axis.

Extensor hood area

Formed by the extensor expansion proximally, covers the head of the metacarpal and keeps the extensor tendon in midline.

Colles' fracture

Fracture of distal radius secondary on outstretched hand.

Functional position of the hand

In this position, the wrist is in a slightly hyperextended (dorsiflexed) position, the MCP and PIP joints of the fingers are slightly flexed, the thumb is in opposition, and the the transverse and longitudinal arches are normal. Position allows hand to be most effective in stength & position.

DeQuervain's Tenosynovitis

Inflammation and thickening of sheath containing Extensor Pollicis Brevis and Adductor Pollicis Longus. - Pain on radial side of the wrist -Tenosynovitis -Finkelstein test

Hook grip

Involves the second through fifth fingers flexed around an object in a hooklike manner, the MCP joints are extended and the PIP and DIP joints are in some degree of flexion. Ex--> holding a suitcase

Flexor retinaculum

Is a fibrous band of connective tissue that spans the anterior surface of the wrist in a mediolateral (horizontal) direction. It attaches to the styloid processes of the radisu and ulna and crosses over the flexor muscle tendons. Its main function is to hold these tendons close to the wrist, thus preventing the tendons from pulling. This also called "Tie Beam".

Extensor retinaculum

Is a fibrous band traversing the posterior side of the wrist in a horizontal mediolateral direction. It attaches medially to the styloid process of the ulna and to the triquetrum, pisiform, and lateral side of the radius. It holds the extensor tendons close to the wrist, especially during wrist extension.

Metacarpophalangeal Joints (MCP)

Is a hinge joint that allows only flexion and extension, and is therefore a uniaxial joint.

carpal tunnel syndrome

Is an extremely common condition caused by compression of the median nerve within the carpal tunnel. Symptoms include numbness and tingling in the hand, which often begins at night. Transverse carpal ligament surgically cut to relieve the symptoms.

Distal interphalangeal joint (DIP)

Is formed by the base of the distal phalanx articulating with the head of the middle phalanx. Uniaxial joint.

Proximal carpal arch

Is formed by the proximal end of the metacarpals (base) and carpal bones and is maintained by the flexor retinaculum.

Distal carpal arch

Is made up of the metacarpal heads

Carpometacarpal Joint CMC

Is made up of the trapezium bone, which articulates with the base of teh first metacarpal. It is most commonly described as a modified biaxial saddle joint. Both joint surfaces are consave and convex, can be compared to a pringles chip. The rotation at the CMC joint is a passive, not voluntary, motion. This rotation occurs as a result of joint's shape and not by any muscle action. This commly referred to as accessory movement.

Proximal interphalangeal joint (PIP)

Is the articulation between the base of the middle phalanx and the head of the proximal phalanx. Uniaxial joint.

MCP Joints

Known as "knuckles". Bi-axial condyloid its with 2 degrees of freedom. Convexsurface of metacaroal articulation of the phalanx. The 3rd finger is point of reference for abduction/adduction. Abduction: 2nd, 4th, & 5th fingers return from abduction. No adduction in the middle finger.

Lumbrical grip

Known as the plate grip; MCP joints are flexed DIP extended and thumb opposes finger holding object horizontally (plate).

The hand is made up of what structures?

Metacarpals & phalanges

CMC Joints

Non-axial synovial joints that provide slight gliding motions (provide more stability then mobility).

Three-jaw chuck

Pad-to-pad grip between thumb and two fingers. Ex-holding a pencil.

4 commonly recognized types of precision grips

Pad-to-pad grip; pinch grip; three-jaw chuck; tip-to- tip grip.

Two types of prehension

Power grips and precision grips

What is the primary function of the hand?

Primary function of the hand is to grasp or prehension. -Shoulder girdle and shoulder joint position hand in space. -Elbow allows hand to move toward or away from body -Wrist provides stability during object manipulation Also has non-prehensile fuctions: scratching, pushing with open palm etx.

Sensory Innervations of the Hand

Radial Nerve--> Dorsum of 1st-lateral 4th finger and volar aspect of thumb. Median Nerve--> Dorsum of 2nd-4th finger tips and volar aspect of 1st-lateral 4th finger. Ulnar nerve--> Medial 4th finger and 5 finger on dorsal/volar aspects.

CMC Joint

The 5th MC is most mobile & allows same 5th finger opposition. 4th MC less mobile. 2nd/ 3rd MC non-mobile.

Pad-to-pad grip

The MCP and PIP joints of the finger(s) are flexed, the thumb is abducted and opposed, and the distal joints of both are extended, bringing the pads of the finger(s) and thumb together.

The hand is made up of how many structures?

The hand is made of the thumb and four fingers, has five metacarpals, five proximal phalanges, and five distal phalanges, but only four middle phalanges.

Interphalangeal Joints (IP)

The only phalangeal joint of the thumb, also allows only flexion and extension. Uniaxial hinge joints.

What are three commonly described power grips?

The three commonly described power grips are cylindrical, spherical, and hook.

Joint structures for the index, middle, ring, and little finger

These joints are the CMC joint, MCP Joint, proximal interphalangeal (PIP) joint, and distal interphalangeal (DIP) joint.

Arthrokinematics for MCP & ICP Joints

They have a concave-on-convex articulation where the concave base on the proximal end of the distal segment articulates with the convex head on the distal end of the proximal segment.

Dupuytren's Contracture

Thickening of palmar aponeurosis at the 4th-5th digits, resulting in flexion contractors.

How many phalanges do the finger have?

Three phalanges

How many phalanges does the thumb have?

Two phalanges

What hinge joint is the PIP and DIP?

Uniaxial hinge joints, allowing for flexion and extension, which occurs in the sagittal plane.

Spherical grip

all the fingers and thumb abducted around an object and unlike cylindrical grip, the fingers are more spread apart. Ex- picking up a glass by its top.

Phalen's test

carpal tunnel syndrome- compression of median nerve

Cylindrical grip

has all the fingers flexed around the object, which usually lies at the right angle to the forearm. Example holding screwdriver.

Pinch grip

pad to pad grip with thumb and one finger usually index finger