Part 5

Types of Body MovementsMuscles are attached to no less than two

pointsOrigin – The attachment to the immovable or

less movable bone Insertion – The attachment

to the movable bone When the muscle contracts

the insertion moves towards the origin

Common Types of Body MovementsFlexion – A movement that decreases

the angle of the joint and brings two bones closer togetherExample – Bending the knee or

elbow, bending forward at the hip

Common Types of Body MovementsExtension – Opposite of flexion;

Movement that increases the angle, or the distance, between two bones or parts of the bodyExample – Straightening the knee or elbow If extension is greater than 180

degrees, it is hyperextension

Common Types of Body MovementsRotation – The movement of a bone

around its longitudinal axisCommon movement of ball-and-

socket joints Example – Movement of the atlas

around the dens of the axis (as in shaking your head “no”)

Common Types of Body MovementsAbduction – The movement

of a limb away from the midline of the bodyExample – Moving your leg

laterally away from your body; Also applies to the fanning movement of the fingers and toes when they are spread apart

Common Types of Body MovementsAdduction – Opposite of

abduction; The movement of a limb towards the midline of the bodyExample – Moving your leg

medially toward your body

Special Types of Body MovementsDorsiflexion and

Plantar Flexion – Up and down movements of the foot at the ankleDorsiflexion – Lifting the

foot so that its superior surface approaches the shin (standing on your heels)

Plantar Flexion – Depressing the foot (pointing the toes)

Special Types of Body MovementsInversion and Eversion – Also special

movements of the footInversion – The turning of the sole medially Eversion – The turning of the sole laterally

Special Types of Body MovementsSupination and Pronation – Refer to

movements of the radius around the ulna Supination – Movement that occurs when the

forearm rotates laterally so that the palm faces anteriorly, and the radius and ulna are parallel

Pronation – Movement that occurs when the forearm rotates medially so that the palm faces posteriorly, and the radius and ulna form an “X”

Special Types of Body MovementsOpposition – Refers to the action of the

saddle joint between metacarpal 1 and the carpals; The action by which you move your thumb to touch the tips of the other fingers on the same handIt is this unique action that

makes the human hand such a fine tool for grasping and manipulating things

Types of MusclesMuscles can’t push, they can only pull as

they contract.Most often body movements are the result of

the activity of two or more muscles acting together or against each other.

Muscles are arranged in such a way that whatever one muscle can do, other muscles can reverse.

Types of MusclesMuscles work in pairs:

Prime Mover – The muscle that has the major responsibility for causing a particular movement

Antagonist – Muscles that oppose or reverse a movement When a prime mover is active, its antagonist is

stretched and relaxed. Antagonists can be movers in their own right

For example, the biceps of the arm (prime mover of elbow flexion) is antagonized by the triceps (a prime mover of elbow extension).

Types of MusclesSynergists – Help prime movers by

producing the same movement or by reducing undesirable movementsWhen a muscle crosses two or more joints, its

contraction will cause movement in all joints crossed unless synergists are there to stabilize them.

Example – The finger-flexor muscles cross both the wrist and the finger joints. You can make a fist without bending your wrist because synergist muscles stabilize the wrist joints and allow the prime mover to act on the finger joints.

Types of MusclesFixators – Specialized synergists; Hold

bones still or stabilize the origin of a prime mover so all the tension can be used to move the insertion boneExamples –

The postural muscles that stabilize the vertebral column

The muscles that anchor the scapula to the thorax

Naming Skeletal MusclesMuscles are named on the basis

of several criteria:1. Direction of muscle fibers

Rectus (straight) – Its fibers run parallel to that imaginary line

Oblique (slanted) – Its fibers run slanted to the imaginary line

2. Relative size of the muscleMaximus (largest), Minimus (smallest),

Longus (long)For example, the gluteus maximus is the

largest muscle of the gluteus muscle group

Naming Skeletal MusclesMuscles are named on the

basis of several criteria:3. Location of the skull

Some muscles are named for the bone with which they are associated

For example, the temporalis and the frontalis muscles overlie the temporal and frontal bones of the skull

Naming Skeletal MusclesMuscles are named on the

basis of several criteria:4. Number of origins

When the term biceps, triceps, or quadriceps forms part of a muscle name, one can assume that the muscle has 2, 3, or 4 origins, respectively.

For example, the biceps muscle of the arm has two heads, or origins, and the triceps muscle has three.

Naming Skeletal MusclesMuscles are named on the basis of

several criteria:5. Location of the muscle’s origin and

insertionOccasionally, muscles are named for their

attachment sites. For example, the sternocleidomastoid muscle

has its origin on the sternum (sterno) and inserts on the mastoid process of the temporal bone

Naming Skeletal MusclesMuscles are named on the basis of

several criteria:6. Shape of the muscle

Some muscles have a distinctive shape that helps to identify them

For example, the deltoid muscle is roughly triangular (deltoid means triangular)

Naming Skeletal MusclesMuscles are named on the basis of

several criteria:7. Action of the muscle

When muscles are named for their actions, terms such as flexor, extensor, and adductor appear in their names.

Examples - The adductor muscles of the thigh all bring about its adduction; The extensor muscles of the wrist all extend the wrist