Muscle 7

1. In a pennate (feather like) muscle the ______ are arranged at an angle to the tendon. Because the muscle cells pull at an angle, contracting pennate muscles do not move their tendons as far as parallel muscles do. 2. However, a pennate muscle contains more muscle fibers-- and, as a result, produces more _______ than a parallel muscle of the same size. Tension production is proportional to the number of contracting sarcomeres. Where there are a high number of muscle fibers there are more myofibrils and sarcomeres. 3.If all the muscle fibers are on the same side of the tendon the muscle is ________. The extensor digitorum muscle (a forearm muscle that extends the finger joints) is unipennate. More commonly, a pennate muscle has fibers on both sides of the tendon and is referred to as bipennate. The rectus femoris muscle (a muscle that extends the knee) is bipennate. 4.If the tendon _______ within a pennate muscle, the muscle is called multipennate. The triangular deltoid muscle of the shoulder is multipennate.

1. fascicles; 2. tension 3. unipennate 4. branches *looks like fishtail braid

1. Convergent muscle fibers are spread over a broad area, but all the fibers converge at one common attachment site. The _______ muscle has this shape. 2. The main advantage of this muscle is that when only one portion of the muscle is stimulated it can change the direction of pull. The entire muscle can contract in unison, however the muscle fibers do not pull as hard on the attachment site as would a parallel muscle of the same size because the convergent muscle fibers pull in different directions. This ______ their overall force production in any single direction. Parallel muscle fascicles are designed to all pull in the same direction. 3. Body builders find training pectoralis major is a challenge because the fascicles form three major lines of action. There is a superior portion, a middle portion, and inferior portion all producing a slightly different arm action. Pectoralis major internally rotates the arm, abducts the arm and flexes the elbow so you can see that it is a very diverse muscle. Its diversity is due to _______ fascicle architecture.

1. pectoralis; 2. reduces ; 3. divergent

Which type of fascicle arrangement would you expect in a muscle guarding the opening between the stomach and the small intestine?

Circular

Hypertrophy is a term that describes the concentric action of a muscle: T/F

FALSE- an increase in size of the muscle (especially when trained)

An agonist is a muscle whose action.....

Is chiefly responsible for producing a particular movement

Naming criteria: Ex. of "relative position"

Muscles at the body surface are often called externus or superficialis, whereas deeper muscles are termed internus or profundus. Superficial muscles that position or stabilize an organ are called extrinsic. Muscles located entirely within an organ are called intrinsic.

What type of fascicle arrangement does biceps brachia have?

Parallel

______ muscles (fusiform) are the most common. The fibers run parallel to each other along the long axis of the muscle. An example is the _____ muscle. There are parallel muscles that are relatively flat and ending in broad attachments (aponeurosis) at each end. Others are cylindrical with tendons on one, or both ends. In muscles with tendons on both ends the muscle appears spindle-shaped, with a central body (gaster or belly where gaster means stomach). The biceps (an upper arm muscle) is a good example of this type of muscle. An example of a flat muscle is tensor fasciae latae where a thin fibrous sheet takes the place of a tendon. When a parallel muscle contracts, it gets shorter and ______ in diameter. Parallel muscle can move the bone a long distance shortening up to 30% of their overall length.

Parallel; biceps; larger

Rectus means _______ Transverses means ________ oblique means ________

Rectus is straight, transverses is across and oblique is at an angle.

__________ is the form of atrophy of a muscle due to aging and this cannot be reversed.

Sarcopenia

How ar the biceps brachii, triceps, and quadriceps representative of the "number of origins" muscle naming category ?

The biceps brachii for example has two tendons of origin (bi two + caput, head). The triceps muscle has three tendons and the quadriceps has four tendons.

Give an example of the "actions" muscle naming category

The flexor muscle decreases the angle between bones, such as when you are lifting a dumbbell. SOOOO -->The flexor flexes. The extensor increases the angle between two bones (e.g. when you are lowering the dumbbell). The extensor EXTENDS

How does the sternocleidomastoid muscle represent the skeletal naming category of Origins/ insertions?

This muscle originates from the sternum and clavicle. That's the beginning of the muscle. The sternocleidomastoid eventually inserts itself on part of the temporal bone called the mastoid process. We get "sterno" from sternum, and "cleido" from clavicle. Then we get "mastoid" from mastoid process.

An isometric contraction produces muscle tension but there is no movement: T/F

True

The ________ is the muscle causing the movement and the ________ is the muscle on the other side causing the opposite movement

agonist; antagonist

The biceps brachii is the _______ responsible for producing flexion at the elbow. The triceps brachii muscle is an agonist muscle that extends the elbow. It is therefore an ________ to biceps brachii muscle and the biceps brachii muscle is the antagonist of the triceps brachii.

agonist; antagonist

Other rules are used when the origins and insertions cannot be determined easily on the basis of movement. When a muscle extends between a broad aponeurosis and a narrow tendon, the _________ is the origin and the ________ is the insertion. If several tendons are at one end and just one is at the other, the muscle has multiple origins and a single insertion.

aponeurosis ; tendon

An _________ attachment occurs when a flat, sheet like muscle, has a wide attachment area and a thin fibrous sheet takes the place of a tendon.

aponeurotic An ex. is tensor fascia latae

When a muscle is used it will get bigger or it hypertrophies. This is the principle bodybuilders use when they are designing their weight-training program. If the body builder stops working out the muscle will return to its normal size. It will _______ due to disuse.

atrophy

The body will only maintain the functionality of muscle that it needs for chronic daily use. If when you stop training the muscle it will _______ or get smaller. If you start training it again it will ________ once more.

atrophy ; hypertrophy

Gastrocnemius muscle is a calf muscle extending from the distal portion of the femur to the _________. Contraction of gastrocnemius causes the heel to be pulled towards the knee. Therefore gastrocnemius muscle has its origin at the femur and its insertion at the calcaneus. It is an ankle extensor (or plantar flexor).

calcaneus

Naming criteria: Ex. of "shape"

deltoid muscle is triangular. Delta is a Greek symbol shaped like a triangle. Trapezius is in the shape of a trapazoid.

A synergist only causes flexion : T/F

false: synergist helps a larger agonist work efficiently

Origin describes its attachment to an _______ bone while insertions describes its attachment to _______ bone.

immoveable; moveable

In general, the more moveable end of the muscle is the ________

insertion

The site where the moveable end attaches to another structure is called the ________ of the muscle. The origin is typically proximal to the insertion.

insertion

What are the 3 basic actions that muscles can perform?

isometric, concentric and eccentric.

A synergist helps a _______ ________ work efficiently. Synergists may provide additional pull near the insertion or may stabilize the point of origin. For example, the latissimus dorsi muscle is a large trunk muscle that extends, adducts and medially rotates the arm at the shoulder joint.

larger agonist

An eccentric action occurs when the force generated by the muscle is less than the resistance being encountered. This results in a __________ of the active muscle. Eccentric actions are often used when muscles have to slow down body parts, or opposed external resistances.

lengthening (Ex. The downward phase of a biceps curl)

You would expect a skeletal muscle with "oblique" in its name to be ....

located at a diagonal angle to the longitudinal axis of the body

Isometric action is a static action where the muscle generates force in the absence of joint _________. The muscle exerting the force does not change in length even though it is contracting and in this way it is said to contract statically (isometrically).

movement; Ex: When the dumbbell is held at its midpoint of a standing curl exercise the biceps muscles are exerting force but do not change in length.

A circular muscle, or sphincter, is concentrically arranged around an _______. When the muscle contracts, the diameter of the opening _______. Circular muscles guard entrances and exits of internal passageways such as the digestive and urinary tracts. An example is the orbicularis oris muscle of the mouth.

opening ; decreases

In most cases one end of a muscle is fixed, and during contraction the other end moves towards the fixed end. The place where the fixed end attaches to a bone, cartilage, or connective tissue is called the _______ of the muscle.

origin

Skeletal muscles are named using 7 different naming criteria. These naming criteria are: 1. Location, 2. Shape, 3. Relative _________, 4. Direction of fibers or fascicle organization, 5. Origin and insertion, 6. Number of ________ 7. Action.

relative position; number of origins

With advancing age. skeletal muscle fibers become smaller in diameter. This is called_______

sarcopenia

There are also muscular attachments. This occurs when fleshy muscular fibers interlace with other muscular fibers. An example of this is_______ _________

serratus anterior

A concentric action occurs when the muscle force being generated exceeds the resistance and the muscle _______ (such as the upward phase of a biceps curl).

shortens (important for lifting & rapid movement) think: arm motioning "come here"

During isometric contraction the contractile part of the muscle _______ but the elastic connective tissue ________ proportionally. In this way there is no overall change in the entire muscle length.

shortens; lengthens

Naming criteria: Ex. of "location"

temporalis and frontalis muscles are named for the cranial bones underneath them

A __________ attachment occurs when a muscle attaches to bone by way of a tendon.

tendinous

Skeletal muscle is highly organized at both the microscopic and macroscopic level. The way the fascicles are organized influences the functional properties of a whole muscle and its ability to generate force. There are 4 basic fascicle patterns: (List them)

• Parallel muscles • Convergent muscles • Pennate muscles (three types) • Circular muscles