Ch. 11: Muscles of the Body

Skeletal muscles

produce movements (Ex. Blinking of an eye, standing on tiptoe, swallowing food. etc.")

Consist of fascicles

Fascicles

arranged in different patterns

Fascicle arrangement

tells about action of a muscle

Types of fascicle arrangements

Parallel, Convergent, Pennate, Circular, Fusiform, Multipennate, Bipennate, Unipennate

Parallel arrangement

fascicles run parallel to the long axis of the muscle

• Strap-like - sternocleidomastoid

• Fusiform - biceps brachii

Convergent Arrangement

Origin of the muscle is broad

Fascicles converge toward the tendon of insertion

Ex. pectoralis major

Pennate Arrangement

Unipennate, Bipennate, & Multipennate

Unipennate Arrangement

fascicles insert into one side of the tendon

Bipennate Arrangement

Fascicles insert into the tendon from both sides

Multipennate Arrangement

fascicles insert into one large tendon from all sides

Circular Arrangement

Fascicles are arranged in concentric rings

Surrounds external body openings

Ex. Orbicularis oris and Orbicularis oculi

Sphincter

general name for a circular muscle

Lever

a rigid bar that moves

Fulcrum

a fixed point

Effort

applied force at one end

Load

resistance, is between the effort and fulcrum

Movements of skeletal muscles involve leverages such as

Lever, Fulcrum, Effort, Load

Bones

act as levers

Joint

act as fulcrums

Muscle contraction

provides effort

Load

bone, overlying tissue, and anything lifted

Fulcrum, Effort, Load

Levers allow a given effort to- (bone-muscle relationships)

move heavier loads and move loads farther

Mechanical advantage- (bone-muscle relationships)

moves a large loas over small distances

Mechanical disadvantage- (bone-muscle relationships)

allows a load to be moved over a large distance

A First-class lever system

raises your head off your chest. The posterior neck muscles provide the effort; the atlanto-occipital joint is the fulcrum; and the weight to be lifted is the facial skeleton.

Second-class lever system

is exerted when you stand tip-toe. The effort is exerted by the calf muslces pulling upward toward the heel: the joints of the ball of the foot are the fulcrum: and the weight of the body is the load.

A Third-class lever

can be when you’re flexing your forearm by the biceps brachii muscle. The effort is exerted on the proximal radius of the forearm; the fulcrum is the elbow joint; and the load is the hand and distal end of the forearm.

Muscles organized into four groups

Musculature of the visceral organs, pharyngeal arch muscles, axial muscles, limb muscles

Musculature of the visceral organs

includes smooth and cardiac muscle, develops from splanchinic mesoderm

Pharyngeal arch muscles

includes skeletal muscles of the pharynx, muscles of the head and neck

Extensors

muscle mass dorsal to limb bones

Flexors

muscle mass ventral to limb bones

Extensors of the upper limb

triceps brachii, extensor digitorum

Flexors of the upper limb

biceps brachii, flexor carpi radialis

Extensors of lower limb

quadriceps femoris, tibialis anterior

Flexors of the lower limb

hamstrings, gastrocnemius

Prime mover (agonist)

has major responsibility for a certain movement

Antagonist

opposes or reverses a movement

Synergist- helps the prime mover

by adding extra force, and by reducing undesirable movements

Fixator

a type of synergist that holds a bone firmly in place

A muscle that crosses of the posterior side of joint produces extension

example: latissimus dorsi

A muscle the crosses on the anterior side of a joint produces flexion

example: pectoralis major

Dense fibrous connective tissue divides limb muscles into

compartments

Muscles in opposing compartments are

agonist and antagonist pairs

Head muscles

Temporalis, Masseter

Facial muscles

Epicranius, Frontal belly, Orbicularis oculi, Zygomaticus, Orbicularis oris

Neck muscles

Sternohyoid, Sternocleidomastoid, Platysma

Shoulder muscles

Trapezius, Deltoid

Thorax muscles

Pectoralis minor, Serratus anterior, Pectoralis major, Intercostals

Abdomen muscles

Rectus abdominis (abs), Internal oblique, Transversus abdoominis, External oblique

Arm muscles

Triceps brachii, Biceps brachii, Brachialis

Forearm muscles

Pronator teres, Brachioradialis, Flexor carpi radialis, Palmaris longus

Pelvis/Thigh muscles

Iliopsoas, Pectineus

Thigh

Tensor fasciae latae, Sartorius, Adductor longus, Gracilis, Rectus femoris, Vastus lateralis, Vastus medialis

Leg

FIbularis longus, Extensor digitorum longus, Tibialis anterior, Gastro cnemius, Soleus

Pharyngeal constrictors

squeeze food into the esophagus

Head Movement

Sternocleidomastiod

Spelnius capitis and splenius cervicis

Erector Spinae group

largest of the deep back muscles

Lateral and anterior abdominal wall formed by

external oblique, internal oblique, transverses abdominis

Deltoid

large shoulder/arm muslce

Pectoralis major

large chest muscle

movements of the scapula

Trapezius, levator scapulae, rhomboid major, rhomboid minor

Latissimus dorsi

large triangle shaped back muscle

Levator scapulae

goes from scapula up the neck to the cranial bones

Thenar muscles

ball of thumb muscle