Skeletal muscles

How do skeletal muscles interact?

Skeletal muscles work together or in opposition.

Do skeletal muscles push or pull?

Muscles only pull (never push).

What happens to the insertion when a muscle shortens?

The insertion generally moves toward the origin.

What is the role of opposing muscles?

Whatever a muscle (or group of muscles) does, another muscle (or group) 'undoes'.

What are prime movers (agonists) in functional classifications?

Prime movers (agonists) provide the major force for producing a specific movement.

What are antagonists in functional classifications?

Antagonists oppose or reverse a particular movement.

What are synergists in functional classifications?

Synergists add force to movement and reduce undesirable movement or unnecessary movement.

What are fixators in functional classifications?

Fixators are synergists that immobilize a bone or muscle's origin.

What does the location of a skeletal muscle refer to?

The bone or body region associated with the muscle.

What does the shape of a muscle indicate?

The form of the muscle, such as the deltoid muscle being triangular.

What does the term 'maximus' refer to in muscle naming?

It indicates the largest muscle.

What does the term 'minimus' refer to in muscle naming?

It indicates the smallest muscle.

What does the term 'longus' refer to in muscle naming?

It indicates a long muscle.

What does 'rectus' mean in terms of muscle fiber direction?

It means the fibers run straight.

What do the terms 'transversus' and 'oblique' indicate about muscle fiber direction?

They indicate that the fibers run at angles in imaginary directions.

Number of origins

ex biceps

location of attachments

named according to point of origin or insertion

action

flexor or extensor (muscles that flex or extend

What type of fascicle arrangement runs parallel to the long axis of the muscle?

Parallel fascicles

What is a spindle-shaped muscle with fusiform fascicles?

Biceps

What type of fascicle arrangement has short fascicles that attach obliquely to a central tendon?

Pennate fascicles

Which muscle is an example of a pennate fascicle arrangement?

Rectus femoris

What type of fascicle arrangement converges from a broad origin to a single tendon insertion?

Convergent fascicles

Which muscle is an example of convergent fascicles?

Pectoralis major

What type of fascicle arrangement is characterized by fascicles arranged in concentric rings?

Circular fascicles

Which muscle is an example of circular fascicles?

Orbicularis oris

What is a lever?

A lever is a rigid bar that moves on a fulcrum or a fixed point.

What is effort in the context of lever systems?

Effort is the force applied to a lever.

What is load in the context of lever systems?

Load is the resistance moved by the effort.

Anterior

the 40 superficial muscles are divided into 10 regional areas of the body

posterior

the 27 superficial muscles are divided into seven regional areas of the body

What is the name of the bipartite muscle that consists of the frontalis and occipitalis?

Epicranius (occipitofrontalis)

What connects the frontalis and occipitalis muscles?

Galea aponeurotica

What are the alternate actions of the frontalis and occipitalis muscles?

Pulling the scalp forward and backward

How many muscles are involved in facial expressions such as lifting the eyebrows and smiling?

11 muscles

Which cranial nerve innervates the muscles of the face?

Cranial nerve VII (facial nerve)

Where do the facial muscles usually insert?

In skin (rather than bone)

What is a common characteristic of adjacent facial muscles?

Adjacent muscles often fuse

How many pairs of muscles are involved in mastication?

Four pairs

What are the prime movers of mastication?

Temporalis and masseter

Which cranial nerve innervates the muscles of mastication?

Cranial nerve V (trigeminal nerve)

What are the extrinsic tongue muscles?

Three major muscles that anchor and move the tongue.

Which cranial nerve innervates all extrinsic tongue muscles?

Cranial nerve XII (hypoglossal nerve).

muscles that move the anterior neck :suprahyoid

There are four deep throat muscles (above the hyoid bone)

The four muscles are the digastric muscle, stylohyoid , geniohyoid , and mylohyoid

forms the floor of the oral cavity

anchors the tongue

Elevates the hyoid bone

Moves the larynx superiorly during swallowing

What are infrahyoid muscles?

Straplike muscles that depress the hyoid and larynx as swallowing ends and during speaking.

What is the location and classification of the sternohyoid muscle?

Superficial and medial infrahyoid muscle.

What is the location and classification of the omohyoid muscle?

Superficial and lateral infrahyoid muscle.

What is the location and classification of the thyrohyoid muscle?

Deep and lateral infrahyoid muscle.

What is the location and classification of the sternothyroid muscle?

Deep and medial infrahyoid muscle.

What is the major head flexor?

The sternocleidomastoid

What are the synergists to head flexion?

The suprahyoid and infrahyoid muscles

Which muscles accomplish lateral head movements?

The sternocleidomastoid and scalene muscles

What muscles are responsible for head extension?

The deep splenius muscles and the superficial trapezius

What is the primary function of deep thoracic muscles?

To promote movement for breathing.

What do the external intercostals do?

They lift the ribcage and increase thoracic volume to allow inspiration.