Lab 7: Intro to muscles

Origin

• The place where Muscle is attached to the non moveable part/bone

• When that specific muscle is pulling, that part doesn't move

Tendon

• A band of fibrous connective tissue that connects muscle to bone or muscle to muscle 

• Dense regular connective tissue proper

Interstion

The place where the muscle is attached to the moveable bone

Aponeurosis

• A sheet like tendon rather than band like CT

• A thin membrane like sheet

• Connects muscle to bone or muscle to muscle

Agonist

• The muscle that is providing the majority of the force for a movement 

• Eg. Biceps brachii when you are flexing your arm

Antagonist

• Muscle that must be relaxed or extended when the agonist is active

• Eg. triceps brachii when you are flexing your arm

• It is the muscle that becomes active in order to reverse the flexion the bicep brachii

• If you want a smooth movement when you are extending your arm you don't just completely relax the agonist you have to contract the antagonist and partially relax the agonist

• ****NO muscle is always the agonist for every movement, eg. when you are extending the arm the biceps brachii becomes the antagonist

Synergist

• A muscle that assists the agonist

• Can do so in 2 ways (its doing OR not both)

  • 1) Add power to the movement to make sure you add power to the movement

  • 2) Stabilize/immobilize the origin 

    • A Fixator

Fixators

• If it stabilizes the origin it is also known as the origin

• It is a smaller group within the synergist

frontal belly of epicranius

orbicularis oris

orbicularis oculi

Zygomaticus

pectoralis major

pectoralis major

pectoralis major

pectoralis minor

D

pectoralis minor

1

pectoralis major

internal intercostal

A

Frontal belly of epicranius

D

Orbicularis oris

G

Orbicularis oculi

E

Masseter

B

Temporalis

F

Zygomaticus

A

External intercostal

internal intercostal

Diaphragm

A

SternoCleidoMastoid

B

Middle Scalenes

C

Anterior scalenes

D

Posterior scalene

A

Transverse abdominis

B

External oblique

C

Transverse abdominis

D

internal oblique

E

Linea Alba

A

External oblique

B

Rectus abdominis

C

Pectoralis major

D

pectoralis minor

A

pectoralis major

B

pectoralis minor

A

External oblique

B

Transverse abdominis

C

Rectus abdominis

D

Internal oblique

A

pectoralis major

B

pectoralis minor

Origin, Insertion, action of Pectoralis Major

• Origin: Sternum

• Insertion: Greater tubericle of humerus

• Action: Adducts and medially rotates arm

Origin, Insertion, action of Pectoralis Major

• Origin: Sternum

• Insertion: Greater tubericle of humerus

• Action: Adducts and medially rotates arm

Origin, Insertion, action of Pectoralis Minor

• Origin: Anterior surfaces of ribs 3-5

• Insertion: Coracoid process of scapula

• Action: With ribs fixed, pulls scapula forward and downward

Origin, Insertion, action of Pectoralis Minor

• Origin: Anterior surfaces of ribs 3-5

• Insertion: Coracoid process of scapula

• Action: With ribs fixed, pulls scapula forward and downward

Origin, Insertion, action of Rectus abdominis

• Origin: Pubic crest

• Insertion: Xiphoid process

• Action: flex and rotate lumbar region of vertebral column

Origin, Insertion, action of Rectus abdominis

• Origin: Pubic crest

• Insertion: Xiphoid process

• Action: flex and rotate lumbar region of vertebral column

Origin, Insertion, action of External obliques

• Origin: Fleshy strips from outer surfaces of lower 8 ribs

• Insertion: Lina alba

• Action:

  • flex vertebral column

  • compress abdominal wall

  • trunk rotation and lateral flexion

Origin, Insertion, action of External obliques

• Origin: Fleshy strips from outer surfaces of lower 8 ribs

• Insertion: Lina alba

• Action:

  • flex vertebral column

  • compress abdominal wall

  • trunk rotation and lateral flexion

Origin, Insertion, action of internal obliques

• Origin: Iliac crest

• Insertion: Linea alba

• Action:

  • flex vertebral column

  • compress abdominal wall

  • trunk rotation and lateral flexion

Origin, Insertion, action of internal obliques

• Origin: Iliac crest

• Insertion: Linea alba

• Action:

  • flex vertebral column

  • compress abdominal wall

  • trunk rotation and lateral flexion

Origin, Insertion, action of transverse abdominis

• Origin: iliac crest

• Insertion: linea alba

• Action: compresses abdominal contents

Origin, Insertion, action of transverse abdominis

• Origin: iliac crest

• Insertion: linea alba

• Action: compresses abdominal contents

Origin, Insertion, action of sternocleidomastoid

• Origin: Manubrium of sternun

• Insertion: mastoid process of temporal bone

• Action: flexes and laterally rotates the head

Origin, Insertion, action of sternocleidomastoid

• Origin: Manubrium of sternun

• Insertion: mastoid process of temporal bone

• Action: flexes and laterally rotates the head

Origin, Insertion, action of anterior scalenes

• Origin: Transverse process of the cervical vertebrae

• Insertion: Anterolaterally on first rib

• Action: elevates first 2 ribs

Origin, Insertion, action of anterior scalenes

• Origin: Transverse process of the cervical vertebrae

• Insertion: Anterolaterally on first rib

• Action: elevates first 2 ribs

Origin, Insertion, action of middle scalenes

• Origin: Transverse process of the cervical vertebrae

• Insertion: Anterolaterally on first rib

• Action: elevates first 2 ribs

Origin, Insertion, action of posterior scalenes

• Origin: Transverse process of the cervical vertebrae

• Insertion: Anterolaterally on first 2 ribs

• Action: elevates first 2 ribs

2 differences between the human and cat muscle groups

1) Sternocleidomasoid not connected to clavical in the cat but it is in humans and is called sternomastioid in cats

2) Pectoralis Major and Minor has different shapes in cat and the sizes are different

sternomastoid

sternomastoid

Major Structural features of skeletal muscle

• Striations: Yes

• Nucleus: Multiple nuclei

• Intercalated discs: None

• Shape: 

  • Long cylinder

  • Striated

  • Multi-nuceated

Major Structural features of cardiac muscle

• Striations: Yes

• Nucleus: 1-2

• Intercalated discs:  Yes

• Shape:

  • Branched shape

  • 1-2 nucleus

  • Strations

  • Looks like x’s and y’s

  • you can see white spaces between the cells

Major Structural features of smooth muscle

• No Striations

• Nucleus 

• Intercalated discs: None

• Shape:

  • Spindle shape

  • No striations

  • 1 nucleus per cell

  • Stacked on top of each other