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Flashcards in A&P 1.12 Deck (30)
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1

Sternocleidomastoid

SCM


A, I, O

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

2

Sutures in the skull

All adjacent to Parential Bone

Coronal - Frontal bone

Lambdoid - Occipital bone

Squamous - Temporal Bone

3

Sternum parts

3 main parts

Manubrium
Body
Xiphoid

4

Function of muscles

3

Movement

Heat production

Posture

5

Layers of muscles

3

Muscle - organ ---- epimysium

Fascicles- bunches of muscle ----- perimysium

Fibers- muscle cells --- endomysium

6

Connective tissue covering muscles

3

Epimysium

Perimysium

Endomysium

7

Muscle action

4

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

8

Muscle fiber

Muscle cell

Generally run the length of muscle

Have threadlike shape

9

Sarcolemma

Define

Sarco - flesh, lemma - sheath

Plasma membrane of the muscle fiber

10

Transverse (T) tubules

Defined

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

11

Sarcoplasmic reticulum

Network of tubules and sacs ( not T tubules)

Wrapped around T Tubules and store calcium

12

Sarcoplasm

The cytoplasm of the muscle fiber

13

Nuclei

Unlike other cells skeletal muscle fibers have several nuclei

14

Myofibrils

Described

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*****

15

Thick filaments

Described

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

16

Thin filaments

Described

Made up of three proteins: actin, tropomysin, and troponin
Actin molecules are strung together like beads to form 2 fibrous strands

17

Sarcomere

Described

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

18

Function of the skeletal muscle

3

Motor unit

Tetanus

Muscle tone

19

Motor unit

Description

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)

20

Tetanus

Described

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")

21

Muscle tone

Described

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.

22

Normal posture

Defined

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.

23

Muscle contraction = sliding filament mechanism

5 parts

Motor neurons
Neurotransmitter
Excitation
Contraction
Relaxation

24

Motor neuron

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

25

Neurotransmitter

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

26

Excitation

When the electrical impulse going to next cell

27

Contraction

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.

28

Relaxation

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

29

Action of a muscle

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

30

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

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