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Muscular System Cheat Sheet by

Muscular system cheat sheet

Types of muscle tissue


Movement of thigh and Leg

- Grouped according to anterior, medial, or posterior
- Most anterior muscles flex femur at hip, extend leg at knee
- Most posterior muscles extend thigh, flex leg
- Medial muscles all adduct thigh
- All three groups enclosed by fascia late

- Include flexion, extension, abduction, adduction, circum­duc­tion, and rotation

- Thigh flexor pass in front of hip joint
- liposoas: primary mover of flexion
- Tensor fasciae latae
- Rectus femoris
- Assisted by medial adductors and sartorial

Thigh extensor
- Hamstring muscles: prime movement of extension

- Quadricep femoris arise from four separate heads that form the flesh of front and side of thigh
- All insert into the quadricep tendon which then inserts into the patella, ad then via patellar ligament, into the livid tuberosity
- powerful knee extensor

Smooth Muscle

Smooth Muscle Tissue: Found in walls of hollow organs
not striated
Involu­ntary: cannot be controlled consci­ously

4 Main charac­ter­istics of Muscle Tissue

Ability to receive and respond to stimuli
Ability to shorten forcibly when stimulated
Ability to be stretched
Ability to recoil to resting length

Compre­ssion of abdominal viscera

Four paired muscles
- Rectus abdominis
- external obliques
- internal obliques
- transverse abdominis

Head Movement and Trunk Extension

Antero­lateral neck muscles
Intrinsic Muscles of the back
Move head
extend trunk and maintain posture


myofibril features
densely packed, rodlike elements
80% of muscle cell volume
molecular compos­ition of muofil­aments

Sliding filament Model of Contra­ction

Sliding filament model of contra­ction
the activation of cross bridges to generate force
During contra­ction, thin filaments slid past thick filaments, causing actin and myosin to overlap more
shortening occurs when tension generated by cross bridges on thin filaments exceed forces opposing shortening
When nervous system stimulates muscle fiber, myosin heads are allowed to bind to action forming cross bridges
contra­ction ends when bridge become inactive

Mastic­ation ad tongue movement

Muscle of mastic­ation
four pairs all innervated by cranial nerve V
prime mover of jaw closure: tempralis and master
grinding movement; pterygoids
chewing role: buccinator

Fascicle Arrang­ements (cont.)

different forms
short fascicles attach obliquely to central tendon running length of muscle
Unipen­nate: fascicles attach only to one side of tendon
Bipennte: fascicles insert from opposite sides of tendon (rectus femurs)
Multip­ennate: appears as feathers inserting into one tendon (example deltoid)

Movement of Ankels and Toes

- Muscles of anterior compar­tment

- primary toe extensors and ankle dorsli­fexors
- Tibialis anterior
- Extensor digitorum longus
- Fibuaris tertius
- Extensor hallucis longus

Muscles of the lateral compar­tment of the leg
- Plantar flexion and eversion of the foot; stabile lateral ankle and lateral longit­udinal arch of foot
- Fibularis longus
- Fibularis brevis

Muscles of the posterior compar­tment f the leg
- act to plantar flex the ankle
- All are innervated by tibial nerve
- Divided into Superf­icial muscles and deep muscles

Humerus Movement

- nine Muscles cross shoulder ring
- Insert on and move humerus
- Some originate from scapula, other from axial skeletion
-action include flexion, extension, adduction
- Three prime movers of arm
1) pectorals major
2) latissimus dorsi
3) Deltoid

- Rotator cuff muscles act as synergist and fixato­rs;­ori­ginate on scapulae reinforce shoulder capsule; prevent disloc­ation
1) supras­pinatus
2) infras­pinatus
3) teres minor
4) subsca­pularis

Swallowing Muscles

Sterno­cle­ido­mastodi muscle divides neck into two triangles
- Anterior muscles are divided based on location to the hyoid bone: supra hyoid and infra hyoid
- Tongue and buccinator muscles push food back towards pharynx, where muscles in posterior mouth and pharynx complete swallowing process
- Epiglottis closes over larynx while muscles in walls of pharynx propel food forward to stomach


Facial Expres­sions

Facial expression muscles are different because they insert into skin not bone
Facial expression muscles consists of two groups
Important nonverbal commun­ication
Muscles of the scalp
muscles of the face

Muscle Action and Intera­ction

muscle can only pull; never push
3 main function group
what one muscle group does the other undoes
Prime mover: major respon­sib­ility for producing specific movement
Antago­nist: opposes or reverses particular movement
Syngerist: Helps prime mover; adds extra force to same movement; reduces undesi­rable or unnece­ssary movement; Fixator: type that immobi­lizes bone or muscle organ rather than enhancing movement of Prime movers


Stripes formed from repeating series of dark and light bands along length of each myofibril
Smallest contra­ctile unit of muscle fiber
Actin myofil­aments: Thin filament; extend across I band and partway in A band
A band= dark region
Contains A band with half of an I band at each end
myosin Myofil­aments: Thick filaments: extend length of A band
I band= lighter region

Muscle Fiber Microa­natomy

muscle fiber plasma membrane
muscle fiber cytoplasm

Muscle Functions

Produce movement
Maintain posture and body position
Stabilize joints
Generate heat as the contract
Respon­sible for all locomotion and manipu­lation

Skeletal Muscle

Skeletal muscle tissue
Skeletal muscle fibers
packaged into skeletal muscles: organs that are attached to bone and skin
Longest of all muscle and have striations (stripes)
also called voluntary muscle: can be consci­ously controlled

Fascicle Arrang­ements

All skeletal muscle consists of bundles of fibers
The most common patterns of arrang­ement
Variation results i muscles with different shapes and functional capabi­lities
Circular: fascicles arranged in concentric rings
Conver­gent: broad organ; fascicles converged toward single tendon insertion
parallel: Fascicles parallel to long axis of traplike muscle (stria­tion)
Fusiform: Spindle shaped muscle with parallel fibers (bicep brachia)

Swallowing Muscles (Cont)

Infrahyoid Muscles
Suprahyoid Muscles
- four strap like muscles
Four deep muscles involved in swallowing
Depressed hyoid bone and larynx during swallowing and speaking
1) Form floor or oral cavity 2) Anchor tongue 3) Elevated hyoid bone 4) Move larynx during swallowing


contra­ction of the muscles enlarge the rib cage
Relaxation of muscles decrease size of rib cage
Diaphram divides thoracic and abdominal cavities

Skeletal Muscle Anatomy

Nerve and blood Supply
Connective tissue sheaths
each muscle receives a nerve, artery, and veins
Muscles covered in connective tissue
muscle span joints and attach to bone
consci­ously controlled skeletal muscles has nerves supplying every fiber to control activity
Support cells and reinforces whole muscles
Muscles attach to bone in two places Insertion: Attachment to movable bone: Orgion: attachment to oimmovable bone
Contra­cting muscles fivers require huge amounts of oxygen and nutrients
Epimysium: Dense irregular connective tissue surrou­nding entire muscle; may blend with fascia
Direct Attach­ment: Epimysium fused to periosteum of bone or perich­ondrium of cartilage
need waste products removed quickly
Perimy­sium: Fibrous connective tissue surrou­nding fascicles
Indirect: Connective tissue wrapping extend beyond muscle as roselike tendon or sheetlike aponeu­rosis
Endomy­sium: Fine areolar connective tissue surrou­nding each muscle fiber

Scapula and arm

- Most are the extrinsic shoulder muscles
- act in combin­ation to fit shoulder girls; Move it to increase range of arm movements
- action: elevation, depres­sion, rotation, lateral and medial movements, protra­ction and retraction
Two groups of muscle
- Muscle of the anterior thorax
- muscles of the posterior thorax

Movement of Wrist, Hand, and Fingers

- Divide into anterior and posterior muscles
- Most anterior muscles are flexors
- Most posterior muscles are extensors
- further divided into superf­icial and deep muscles
- Action: Movement of wrist, finger, thumb, as well as pronation and supination of forearm
- Pronator teres and pronator quadratus pronate forearm
- Supina­tion: synergist with biceps brachia in forearm supination

Anterior Muscles
- Consist of five superf­icial and three deep muscles
- Most arise from common flexor tendon attached to medial epicondyle of humerus
- Most tendons of insertion held in lace at wrist be flexor retina­culum

Posterior Muscles
- consists of four superf­icial and four deep muscles
- All are innervated by the radial nerve or its branches
- Most arise from common flexor tendon attached to lateral epicondyle of humerus
- Most tendons of insertion help in lace at wrist by extensor retina­culum

Cardiac Muscle

Cardiac muscle tissue: is found only in heart
makes up bulk of heart walls; striated
involu­ntary; cannot be controlled consci­ously


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