MUSCULAR SYSTEM (2)

type body movements- naming

**origin**

is attached to the immovable or less movable bone. Think of it as the anchor, or leverage, point.

**insertion**

is attached to the movable bone. When the muscle contracts, the insertion moves toward the origin

**Flexion**

is a movement, generally in the sagittal plane, that decreases the angle of the joint and brings two bones closer together

**Extension**

is the opposite of flexion, so it is a movement that increases the angle, or distance, between two bones or parts of the body (straightening the knee or elbow).

**hyperextension**

Extension that is greater than 180° (as when you move your arm posteriorly beyond its normal anatomical position, or tip your head so that your chin points toward the ceiling) is called

**Rotation**

is movement of a bone around its longitudinal axis. a common movement of ball-and socket joints and describes the movement of the atlas around the dens of the axis (as in shaking your head “no”).

**Abduction**

is moving a limb away (generally in the frontal plane) from the midline, or median plane, of the body. also applies to the fanning movement of your fingers or toes when they are spread apart.

**Adduction**

is the opposite of abduction, so it is the movement of a limb toward the body midline. “adding” a body part by bringing it closer to the trunk

**Circumduction**

is a combination of flexion, extension, abduction, and adduction commonly seen in ball-and-socket joints, such as the shoulder

**(1) Dorsiflexion and plantar flexion, (2)Inversion and eversion, (3) Supination and pronation, and (4) Opposition**

Special Movements, certain movements do not fit into any of the previous categories and occur at only a few joints: (4)

**Dorsiflexion and plantar flexion**

Up-and down movements of the foot at the ankle are given special names.

**dorsiflexion**

Lifting the foot so that its superior surface approaches the shin (pointing your toe toward your head) is

**plantar flexion**

whereas pointing the toes away from your head is

**dorsiflexion of the foot**

corresponds to extension and hyperextension of the hand at the wrist

**plantar flexion of the foot**

corresponds to flexion of the hand.

**Inversion and eversion**

To invert the foot, turn the sole medially, as if you were looking at the bottom of your foot. To evert the foot, turn the sole laterally.

**Supination and pronation**

refer to movements of the radius around the ulna

**Supination**

“turning backward”

**pronation**

**“turning forward”**

**Supination**

occurs when the forearm rotates laterally so that the palm faces anteriorly (or up) and the radius and ulna are parallel, as in anatomical position

**pronation**

occurs when the forearm rotates medially so that the palm faces posteriorly (or down). brings the radius across the ulna so that the two bones form an X.

**Opposition**

In the palm of the hand, the saddle joint between metacarpal 1. This is the action by which you move your thumb to touch the tips of the other fingers on the same hand. This unique action makes the human hand a fine tool for grasping and manipulating objects.

**prime mover**

The muscle that has the major responsibility for causing a particular movement is called

**antagonists**

Muscles that oppose or reverse a movement are

**Synergists**

help prime movers by producing the same movement or by reducing undesirable movements.

**Fixators**

are specialized synergists. They hold a bone still or stabilize the origin of a prime mover so all the tension can be used to move the insertion bone

**flexion**

A muscle that crosses on the anterior side of a joint produces:

**extension**

A muscle that crosses on the posterior side of a joint produces:

**abduction**

A muscle that crosses on the lateral side of a joint produces:

**adduction**

A muscle that crosses on the medial side of a joint produces:

**muscle action**

The action of a muscle can be inferred by the muscle’s position as it crosses a joint.

**Direction of the muscle fibers**

Some muscles are named in reference to some imaginary line, usually the midline of the body or the long axis of a limb bone. When a muscle’s name includes the term rectus (straight), its fibers or whole structure run parallel to that imaginary line.

**Relative size of the muscle**

Such terms as maximus (largest), minimus (smallest), and longus (long) are sometimes used in the names of muscles—for example, the gluteus maximus is the largest muscle of the gluteus muscle group

**Location of the muscle**

Some muscles are named for the bone with which they are associated. For example, the temporalis and frontalis muscles overlie the temporal and frontal bones of the skull, respectively.

**Number of origins**

When the term biceps, triceps, or quadriceps forms part of a muscle name. For example, the biceps muscle of the arm has two heads, or origins, and the triceps muscle has three.

**Location of the muscle’s origin and insertion**

Occasionally, muscles are named for their attachment sites. For example, the sternocleidomastoid muscle has its origin on the sternum (sterno) and clavicle (cleido) and inserts on the mastoid process of the temporal bone.

**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”), like the Greek letter delta (Δ).

**Action of the muscle**

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

(1) **Direction of the muscle fibers**, (2) **Relative size of the muscle**, (3) **Location of the muscle**, (4) **Number of origins**, (5) **Location of the muscle’s origin and insertion**, (6) **Shape of the muscle**, (7) **Action of the muscle**

List seven criteria used in naming muscles:

**(1) circular, (2) convergent, (3) fusiform, (4) parallel, (5) multipennate, (6) bipennate, and (7) unipennate**

the most common patterns of fascicle arrangement: (7)

**circular pattern**

how are the fascicles arranged in concentric rings

**Circular muscles**

are typically found surrounding external body openings which they close by contracting, creating a valve.

**convergent muscle**

the fascicles converge toward a single insertion tendon. is triangular or fan-shaped, such as the pectoralis major muscle of the anterior thorax

**parallel arrangement**

the length of the fascicles run parallel to the long axis of the muscle, as in the sartorius of the anterior thigh.

**fusiform**

A modification of the parallel arrangement, called--- results in a spindle-shaped muscle with an expanded belly (midsection) and tapered ends.

**pennate pattern**

short fascicles attach obliquely to a central tendon. (“feather”)

**unipennate**

In the extensor digitorum muscle of the leg, the fascicles insert into only one side of the tendon, and the muscle is

**bipennate**

If the fascicles insert into opposite sides of the tendon, the muscle is

**multipennate**

If the fascicles insert from several different sides, the muscle is

**muscle power**

depends more on the total number of muscle fibers in the muscle

**muscle’s fascicle arrangement**

determines its range of motion and power

**stocky bipennate and multipennate muscles**

pack in the most fibers, shorten very little but are very powerful, like the rectus femoris of the anterior thigh.

(1) **facial muscles** and (2) **chewing muscles**

head muscles are usually grouped into two large categories:

**facial muscles**

are unique because they insert into soft tissues, such as other muscles or skin. When they pull on the skin of the face, they permit us to express ourselves by frowning, smiling, and so forth

**chewing muscles**

begin to break down food for the body

(1) **platysma**, (2) **orbicularis oris**, (3) **frontalis**, and (4) **occipitalis**

All head and neck muscles we describe are paired except for the: (4)

**frontalis**

covers the frontal bone, runs from the cranial aponeurosis to the skin of the eyebrows, where it inserts. This muscle allows you to raise your eyebrows, as in surprise, and to wrinkle your forehead

**occipitalis muscle**

covers the posterior aspect of the skull and pulls the scalp posteriorly. At the posterior end of the cranial aponeurosis

**Orbicularis Oculi**

the fibers run in circles around the eyes. It allows you to close your eyes, squint, blink, and wink

**Orbicularis Oris**

is the circular muscle of the lips. Often called the “kissing” muscle, it closes the mouth and protrudes the lips

**Buccinator**

runs horizontally across the cheek and inserts into the orbicularis oris. It flattens the cheek (as in whistling or blowing a trumpet). It is also listed as a __chewing muscle__ because it compresses the cheek to hold food between the teeth during chewing

**zygomaticus**

extends from the corner of the mouth to the cheekbone. It is often referred to as the “smiling” muscle because it raises the corners of the mouth.

**masseter**

covers the angle of the lower jaw. This muscle elevates the mandible to close the jaw.

**temporalis**

is a fan-shaped muscle overlying the temporal bone. It inserts into the mandible and acts as a synergist of the masseter in closing the jaw.

**neck muscle**

move the head and shoulder girdle, are small and straplike

(1) **Platysma**, (2) **Sternocleidomastoid**

what are considered the 2 neck muscles:

**Platysma**

is a single sheetlike muscle that covers the anterolateral neck. Its action is to pull the corners of the mouth inferiorly, producing a downward sag of the mouth (the “sad clown” face)

**Sternocleidomastoid**

are two-headed muscles, one found on each side of the neck. when this contract together, they flex your neck. (It is this action of bowing the head that has led some people to call these muscles the “prayer” muscles.)

(1) **Frontalis and Occipitalis**, (2) **Orbicularis Oculi**, (3) **Orbicularis Oris**, (4) **Buccinator**, (5) **Zygomaticus**, (6) **Masseter**, (7) **Temporalis**

what are the 7 facial muscles:

**torticollis**

In some difficult births, one of the sternocleidomastoid muscles may be injured and develop spasms. A baby injured in this way has:

(1) **posterior antigravity muscles**, (2) **anterior thorax muscles**, (3) **muscles of the abdominal wall**

The trunk muscles include (3):

**Pectoralis Major**

is a large fan-shaped muscle covering the upper part of the chest. Its origin is from the sternum, shoulder girdle, and the first six ribs. It inserts on the proximal end of the humerus. This muscle forms the anterior wall of the axilla (armpit) and acts to adduct and flex the arm

**Intercostal Muscles**

are deep muscles found between the ribs.

**external intercostals**

which lie toward the lateral edge of the rib cage, are important in breathing because they help to raise the rib cage when you inhale

**internal intercostals**

which lie deep and medial to the external intercostals, depress the rib cage, helping to move air out of the lungs when you exhale forcibly.

(1) **Rectus abdominis**, (2) **External oblique**, (3) **Internal oblique**, (4) **Transversus abdominis**

What are the 4 Muscles of the __*Abdominal Girdle*__:

**anterior abdominal muscles**

forms a natural “girdle” that reinforces the body trunk

**rectus abdominis**

The paired straplike rectus abdominis muscles are the most superficial muscles of the abdomen. They run from the pubis to the rib cage, enclosed in an aponeurosis. Their main function is to flex the vertebral column. They also compress the abdominal contents during defecation and childbirth (they help you “push”) and are involved in forced breathing.

**external oblique**

are paired superficial muscles that make up the lateral walls of the abdomen. Their fibers run downward and medially from the last eight ribs and insert into the ilium.

**internal obliques**

are paired muscles deep to the external obliques. Their fibers run at right angles to those of the external obliques. They arise from the iliac crest and insert into the last three ribs. Their functions are the same as those of the external obliques.

**Transversus abdominis**

The deepest muscle of the abdominal wall. Has fibers that run horizontally across the abdomen. It arises from the lower ribs and iliac crest and inserts into the pubis. This muscle compresses the abdominal contents like a wide belt.

(1) **Trapezius**, (2) **Latissimus Dorsi**, (3) **Erector Spinae**, (4) **Quadratus Lumborum**, (5) **Deltoid**

what are the 5 posterior muscles?

**Trapezius**

are the most superficial muscles of the posterior neck and upper trunk. When seen together, they form a diamond- or kite-shaped muscle mass. Their origin is very broad. extend the head (thus they are antagonists of the sternocleidomastoids). They also can elevate, depress, adduct, and stabilize the scapula.

**Latissimus Dorsi**

are the two large, flat muscles that cover the lower back. They originate on the lower spine and ilium and then sweep superiorly to insert into the proximal end of the humeru. These are very important muscles when the arm must be brought down in a power stroke, as when swimming or striking a blow.

**Erector Spinae**

is the prime mover of back extension. These paired muscles are deep muscles of the back.

(1) **longissimus**, (2) **iliocostalis**, (3) **spinalis**

Each *erector spinae* is a composite muscle consisting of __three muscle columns:__

**Quadratus Lumborum**

form part of the posterior abdominal wall. Acting separately, each muscle of the pair flexes the spine laterally. Acting together, they extend the lumbar spine. These muscles arise from the iliac crests and insert into the upper lumbar vertebrae

**Deltoid**

are fleshy, triangle-shaped muscles that form the rounded shape of your shoulders. Because they are so bulky, they are a favorite injection site when relatively small amounts of medication (less than 5 ml) must be given intramuscularly (into muscle). are the prime movers of arm abduction.

(1) **first group includes muscles that arise from the shoulder girdle and cross the shoulder joint to insert into the humerus**, (2) **The second group causes movement at the elbow joint**., (3) **The third group of upper limb muscles includes the muscles of the forearm, which insert on the hand bones and cause their movement**

The *upper limb muscles* fall into __three groups:__

(1) **the pectoralis major**, (2) **latissimus dorsi**, and (3) **deltoid**.

muscles that moves the arm: (3)

**All anterior muscles**

what muscles of the humerus cause elbow flexion

(1) **Biceps Brachii**, (2) **Brachialis**, (3) **Brachioradialis**, (4) **Triceps Brachii**

what are the __four__ Muscles Causing Movement at the __*Elbow Joint*__

**Biceps Brachii**

is the most familiar muscle of the arm because it bulges when you flex your elbow. This muscle is a powerful prime mover for flexion of the forearm and acts to supinate the forearm. The best way to remember its actions is to think of opening a bottle of wine. The biceps supinates the forearm to turn the corkscrew and then flexes the elbow to pull the cork.

**Brachialis**

s lies deep to the biceps brachii and, like the biceps, is a prime mover in elbow flexion. lifts the ulna as the biceps lifts the radius.

**Brachioradialis**

is a fairly weak muscle that arises on the humerus and inserts into the distal forearm. Hence, it resides mainly in the forearm and aids elbow flexion.

**Triceps Brachii**

is the only muscle fleshing out the posterior humerus. Being the powerful prime mover of elbow extension, it is the antagonist of the biceps brachii and brachialis. This muscle straightens the arm—for instance, to deliver a strong jab in boxing.

**pelvic girdle**

is composed of heavy, fused bones that allow little movement, no special group of muscles is necessary to stabilize it

**origin and insertion**

are often interchangeable depending on the action being performed.

**massive muscles**

Muscles acting on the thigh that help hold the body upright against the pull of gravity and cause various movements at the hip joint

(1) **Gluteus Maximus**, (2) **Gluteus Medius**, (3) **Iliopsoas**, (4) **Adductor Muscles**

__Four__ Muscles Causing Movement at the __*Hip Joint*__