Chapter 10- The Muscular System

A&P 1 Lecture

Movement, stability, control of openings and passageways, heat production, glycemic control

functions of the muscles (5)

Movement

fucntion of muscle: place to place and throughout the body

Stability

function of muscle: stabilize the joints

Control of openings and passageways

function of muscle: sphincters- internal circular rings, controlling the movement of contents, in stomach, eyes, and mouth

Heat production

function of muscle: 85% of heat- skeletal muscles generate heat

Glycemic control

function of muscle: controlling blood-glucose levels

Endomysium

Loose CT around each muscle fiber, allows room for capillaries and nerve fibers

Perimysium

Thicker CT layer that wraps fascicles, carries nerves, blood vessels, and stretch receptors

Fascicles

Bundles of muscle fibers wrapped together

Epimysium

Fibrous sheath around entire muscle, outer surface grades into fascia, inner surface sends projection between fascicles to form perimysium

Fascia

Sheet of CT that separates neighboring muscles or muscle groups from each other and the subcutaneous tissue

fusiform

parallel

muscle fascicles are all running parallel (image 2)

triangular

image 3

unipennate

fascicles coming from one side (image 4)

bipennate

fasicles coming from both sides (image 5)

multipennate

image 6

circular

weakest, muscle fasciles in circular motion (image 7)

Fusiform

Biceps brachii is what muscle shape

Parallel

Rectus abdominis is what muscle shape

Triangular

Pectoralis major is what muscle shape

Unipennate

Palmar interosseous is what muscle shape

Bipennate

Rectus femoris is what muscle shape

Multipennate

Deltoid is what muscle shape

Circular

Orbicularis oculi is what muscle shape

Fascicle orientation and muscle shape

Strength of a muscle and the direction of its pull are determined by what….. (2)

Muscle compartments

Fasciae package groups of functionally related muscles into compartments, contains nerves and vessels that supply the muscle group, inter muscular septa (very thick faces) separate one compartment from another

Tendons

Indirect attachment to bone

Tendons

Connect muscle to bone

Tendons

collagen fibers of the endo-, peri-, and epimysium continue into this and from there into the periosteum and the matrix of bone

tendon

biceps brachii is a ……

tendon

achilles tendon is a …….

Aponeurosis

Tendon is broad, flat sheet

Retinaculum

Connective tissue band that tendons from separate muscles pass under

Direct (fleshy) attachment to bone

Does not need a tendon and little separation between muscle and bone

Direct (fleshy) attachment to bone

muscle seems to emerge directly from bone

direct (fleshy) attachment to bone

margins of brachialos and lateral head of triceps brachii are exmaples of what

Attatchments of muscles

Origin (stationary end) and insertion (moving end), most skeletal muscles connect to bone, but some attach to dermis, fascia, or other soft connective tissues

origin

attachemnt that is the stationary end

insertion

attachment that is the moving end

Action

Effects of muscle → produce or prevent movement

4 action categories

Prime mover (agonist), synergist, antagonist, fixator

Prime mover (agonist)

Produces most of force during joint action

Synergist

Muscle that aids the prime mover

synergist

stabilize nearby joint; modify direction of movement; may contribute additional force

Antagonist

Opposes the prime mover

antagonist

relaxes to give prime mover control over an action, prevents excessive movement and injury

Fixator

Prevents movement of bone

Antagonistic pairs

Muscles that act on opposite sides of joint

prime mover

for elbow flexion, the brachialis is the functionl group ……

synergist

for elbow flexion, the biceps brachii is the functional group ….

antagonist

for elbow flexion, the triceps brachii is the functional group …..

fixator

for elbow flexion, the muscle that holds scapula firmly in place (rhomboids) is the functional group …..

Intrinsic muscles

Entirely contained (both origin and insertion) within a region

intrinsic muscle

the hand is an exmaple of what kind of muscle

Extrinsic muscles

Act on designated region, but has its origin elsewhere

extrinsic muscles

the finger muscles are what kind of muscles

Innervation

Nerve that stimulates muscle

innervation

enables diagnosis of nerve, spinal cord, and brainstem injuries from their effects on muscle function

Spinal nerves

Arise from the spinal cord

spinal nerves

emerge through intervertebral foramina innervate muscles below the neck

spinal nerves

innervate muscles below the neck

Cranial nerves

Arise from the base of the brain (12 pairs)

cranial nerves

emerge through skull foramina

cranial nerves

innervate the muscles of the head and neck

Blood supply

Muscular system receives about 1.24 L of blood per minute at rest (one-quarter of the blood pumped by the heart), during heavy excursive, total cardiac output rises and the muscular system's share is more than three-quarters (11.6 L/min)

blood supply

capillaries branch extensively through endomysium to reach every muscle fiber

How muscles are named

Latin names describe location, shape, size, direction of muscle fibers, origin and/or insertion, action

Muscles of facial expression

Muscles that insert in the dermis and subcutaneous tissue

muscles of facial expression

tense the skin and produce facial expressions

Scalp, forehead, around the eyes, nose, and mouth, and in the neck

where are muscles of facial expression found in (6)

Muscles of the tongue

Pushes food between molars for chewing (mastication)

muscles of the tongue

forces food into the pharynx for swallowing (deglutition)

muscles of the tongue

crucial importance to speech, intrinsic and extrinsic muscles of the tongue

Depression, elevation, protraction, retraction, lateral and medial excursion

Biting and chewing movements of mandible (6)

Temporalis, masseter, medial pterygoid and lateral pterygoid

muscles of chewing and swallowing (4)

Suprahyoid group

digastric, geniohyoid, mylohyoid, stylohyoid

digastric, geniohyoid, mylohyoid, stylohyoid

suprahyoid group (4)

Suprahyoid group

function: concerned with aspects of chewing, swallowing, and speaking

Infrahyoid group

Omohyoid, sternohyoid, thyrohyoid, sternothyroid,

Omohyoid, sternohyoid, thyrohyoid, sternothyroid (4)

infrahyoid group

Infrahyoid group

Fix hyoid bone from below, allowing suprahyoid muscles to open mouth

pharyngeal constrictors

Drive food into esophagus during swallowing

Muscles acting on the head

Arise from vertebral column, thoracic cage, and pectoral girdle; end on cranial bones

Flexion, extension, lateral flexion, rotation, may cause contralateral and ipsilateral movements

Actions of muscles acting on the head (6)

Flexion

Tipping head forward

Extension

Holding the head erect (upright)

Lateral flexion

Tipping head to one side

rotation

turning the head to the left or right

Contralateral movement

Movement of head towards opposite side

Ipsilateral movement

Movement of head towards same side

Sternocleidomastoid, scalenes

neck flexors (2)

Trapezius, splenius capitols, semispinalis capitis

Neck extensors (3)

Three functional groups of the muscles of the trunk

Muscles of respiration, muscles that support abdominal wall and pelvic floor, movement of vertebral column

Diaphragm, contraction, relation, external intercostals, internal intercostals

Muscles of respiration (5)

Diaphragm

Muscular dome between thoracic and abdominal cavities

Contraction

Flattens diaphragm, enlarges thoracic cavity (inspiration)

Relaxion

Diaphragm rises, shrinks the thoracic cavity (expiration)

external intercoastals

elevate ribs and expands thoracic cavity

internal intercostals

depresses and retracts ribs, compresses thoracic cavity