A&P 1.12

Question 1

Sternocleidomastoid

SCM

A, I, O

Answer 1

Named for it’s attachment. Sterno- sternum Clavicular- clavical mastoid - mastoid process

I: mastoid process of the temporal bone and lateral portion of the superior nuchal line of occiput

O: sternal head: top of the manubrium
Clavicular head: medial one third of the clavicle

Unilaterally: contralateral rotation of the head, ipsilateral flexion of the head/neck

Bilaterally: flexion of the neck, extension of the head

Question 2

Sutures in the skull

Answer 2

All adjacent to Parential Bone

Coronal - Frontal bone

Lambdoid - Occipital bone

Squamous - Temporal Bone

Question 3

Sternum parts

3 main parts

Answer 3

Manubrium
Body
Xiphoid

Question 4

Function of muscles

3

Answer 4

Movement

Heat production

Posture

Question 5

Layers of muscles

3

Answer 5

Muscle - organ —- epimysium

Fascicles- bunches of muscle —– perimysium

Fibers- muscle cells — endomysium

Question 6

Connective tissue covering muscles

3

Answer 6

Epimysium

Perimysium

Endomysium

Question 7

Muscle action

4

Answer 7

Electrically excitable- respond to nervous system

Contractility - ability to get small

Extensibility - ability to stretch

Elasticity - ability to return to neutral state after contraction or stretch

Question 8

Muscle fiber

Answer 8

Muscle cell

Generally run the length of muscle

Have threadlike shape

Question 9

Sarcolemma

Define

Answer 9

Sarco - flesh, lemma - sheath

Plasma membrane of the muscle fiber

Question 10

Transverse (T) tubules

Defined

Answer 10

Extensions of the scacolemma that “tunnel” into the center (or core) of the muscle fibers.

They allow the electrical signals or impulses to move deeper into the cell

Wrap around the organelles or myofibril

Question 11

Sarcoplasmic reticulum

Answer 11

Network of tubules and sacs ( not T tubules)

Wrapped around T Tubules and store calcium

Question 12

Sarcoplasm

Answer 12

The cytoplasm of the muscle fiber

Question 13

Nuclei

Answer 13

Unlike other cells skeletal muscle fibers have several nuclei

Question 14

Myofibrils

Described

Answer 14

Bundles of fine fibers 1000 or more in each muscle fiber
Extend lengthwise along skeletal muscle fibers and almost fill their sarcoplasm
Lying side by side (but not the whole length of the muscle fiber) are thousands of finer fibers called thick and thin myofilaments, which in turn are made up of proteins. Myofilaments are arranged in compartments called sarcomeres.
Organelles*

Question 15

Thick filaments

Described

Answer 15

Made up of protein myosin
Shaped like tubes of golf clubs coming off of them (long shaft bundle together and heads stick out)

Chemically attracted to actin

Question 16

Thin filaments

Described

Answer 16

Made up of three proteins: actin, tropomysin, and troponin

Actin molecules are strung together like beads to form 2 fibrous strands

Question 17

Sarcomere

Described

Answer 17

The basic contractile unit of the muscle fiber
Segment of the myofibril between Z disks (dense plate where thin filaments attach)

Sarco- flesh, comere-measure

Unit of measure

Question 18

Function of the skeletal muscle

3

Answer 18

Motor unit

Tetanus

Muscle tone

Question 19

Motor unit

Description

Answer 19

A single motor neuron and the muscle fibers it innervates (attaches to)

Functional unit
Variable numbers of branches

Few muscle fibers = more precise (fingers, eyes)
Many muscle fibers= less precise (leg/arm)

Question 20

Tetanus

Described

Answer 20

Smooth, sustained contractions (multiple twitch waves) resulting from coordinated contractions of different motto units within the muscle.

This is what we see exhibited by normal skeletal muscle most of the time (raising arm is controlled not “jerky”)

Question 21

Muscle tone

Described

Answer 21

A tonic contraction is a continual, partial contraction of a muscle.
It is a low level continuous contraction characteristic of the muscles of normal individuals when they Are awake. The amount of tension even when the muscle is relaxed.

Question 22

Normal posture

Defined

Answer 22

Normal posture in the presence of gravity is achieved by tonus. Exercising increases the tonus of muscles used. (Relay race when each is tired it’s someone else’s turn to run.

Question 23

Muscle contraction = sliding filament mechanism

5 parts

Answer 23

Motor neurons
Neurotransmitter 
Excitation
Contraction
Relaxation

Question 24

Motor neuron

Answer 24

Special nerve cell that connects to the sarcolemma at the neuromuscular junction

Question 25

Neurotransmitter

Answer 25

Chemical that uses nerves to communicate with the neurotransmitter of the neuromuscular junction is Ach (acetylcholine )

Question 26

Excitation

Answer 26

When the electrical impulse going to next cell

Question 27

Contraction

Answer 27

When the impulse is conducted over sarcolemma inward to the T tubules.
Calcium released the sarcoplasmic reticulum and the “protective” covering (tropomysin ) is moved from the thin filament. With covering removed, the myosin (thick filaments) heads grab thin filaments (actin) and pull towards center of sarcomeres. Thin filaments slide inward, Z disks come together, and the sarcomere shortens, causing shortening of the whole muscle fiber causing shortening of the whole muscle.

Question 28

Relaxation

Answer 28

Sarcoplasmic reticulum pumps calcium back into sacs again shutting down contraction process

Question 29

Action of a muscle

Answer 29

Muscle belly contraction
As the combined contraction of multiple muscle fibers (recruiting) to create a motion
Motor units take turns to maintain action without fatigue

Question 30

What percentage of muscle fibers need to be used to contract a muscle?

Answer 30

In general you will never use 100% of muscle fiber unless you are a power lifter