Chapter 10 Muscular System Flashcards
skeletal muscles can be classified into 3 functional groups
- Agonist, or prime mover = muscle that produces a certain desired movement – e.g. flexion
- Antagonist = muscle contraction whose action that counteracts desired movement – e.g. extension
- Synergists = group of muscles working together to help prime mover produce a movement – e.g. hip flexors, knee extensors
- **fixators = synergist muscles that immobilize a bone while a usually more distal bone is moved
skeletal muscles: Agonist
Agonist, or prime mover = muscle that produces a certain desired movement – e.g. flexion
skeletal muscles: Antagonist
Antagonist = muscle contraction whose action that counteracts desired movement – e.g. extension
skeletal muscles: Synergists
Synergists = group of muscles working together to help prime mover produce a movement – e.g. hip flexors, knee extensors
-**fixators = synergist muscles that immobilize a bone while a usually more distal bone is moved
Skeletal muscles
- most extend from one bone to another and cross at least on joint
- contraction – causes movement – pulling one bone toward another across a joint
- some attached to bone only on one end and to some other tissue on the other end – e.g. to skin of face allowing for facial expressions
Skeletal muscles: Origin
Origin = fixed end of skeletal muscle, usually most stationary and proximal end of muscle
-**head = name given when muscle has multiple origins that converge to form one muscle
triceps brachii
Skeletal muscles: Insertion
Insertion = mobile end – usually the distal end attached to the bone undergoing the greatest movement
Skeletal muscles: Belly
Belly = part of muscle between origin and insertion
Skeletal muscle: Tendons
Tendons – long cable-like dense regular connective tissue that attach muscle to bone
o aponeuroses = broad, sheet-like tendons
Skeletal muscle are named according to:
*location
*shape
*muscle size
*direction of muscle fibers
*number of origins
*location of attachments
*muscle action - a muscle that crosses on the:
Anterior side of a joint produces flexion
Posterior side of a joint produces extension
Lateral side of a joint produces abduction
Medial side of a joint produces adduction
Skeletal muscle are named according to: Location
location – e.g. temporalis – covers the temporal bone
Skeletal muscle are named according to: Shape
Shape – e.g. deltoid – roughly triangular
Skeletal muscle are named according to: Muscle size
Muscle size – e.g. gluteus maximus (largest) & minimus (smallest), pollicus longus (long)& brevis (short)
Skeletal muscle are named according to: Direction of muscle fibres
Direction of muscle fibers – e.g. rectus (straight) femoris, transversus abdominus
Skeletal muscle are named according to: Number of origins
Number of origins- e.g. biceps, triceps, quadriceps
Skeletal muscle are named according to: Location of attachments
location of attachments – e.g. sternocleidomastoid (provide origin and insertion)
Skeletal muscle are named according to: Muscle action
Muscle action – e.g. adductor longus (adducts thigh)
a muscle that crosses on the:
• anterior side of a joint produces flexion
• posterior side of a joint produces extension
• lateral side of a joint produces abduction
• medial side of a joint produces adduction
Skeletal muscle: Shape and Size greatly influence the degree to which a muscle can contract and the amount of force it can generate
o classes based on arrangement of fasciculi (bundles of visible muscle fibers)
* Circular – arranged in a circle around an opening and act as sphincters to close opening e. g. orbicularis oris (circles mouth) * Convergent – fasciculi arrive at one common tendon so muscles are triangular in shape e. g. pectoralis major * Parallel – fasciculi parallel to long axis of muscle and terminate on a flat tendon that spans the width of the entire muscle - strap-like – Sartorius - **fusiform = taper at each end onto a tendon – have wider belly – e.g. biceps brachii *Pennate – fasciculi emerge feather-like from a common tendon that runs the entire length of the muscle unipennate = fascicles arise from one side of the tendon only – e.g. extensor digitorum longus bipennate = two sides of the tendon – e.g. rectus femoris multipennate = arranged in many places around central tendon – e.g. deltoid muscle
Skeletal muscle shape: Circular
- Circular – arranged in a circle around an opening and act as **sphincters to close opening
e. g. orbicularis oris (circles mouth)
Skeletal muscle shape: Convergent
- Convergent – fasciculi arrive at **one common tendon so muscles are triangular in shape
e. g. pectoralis major
Skeletal muscle shape: Parallel
- Parallel – fasciculi parallel to long axis of muscle and **terminate on a flat tendon that spans the width of the entire muscle
- strap-like – Sartorius
- **fusiform = taper at each end onto a tendon – have **wider belly – e.g. biceps brachii
Skeletal muscle shape: Pennate
*Pennate – fasciculi emerge feather-like **from a common tendon that runs the entire length of the muscle
unipennate = fascicles arise from one side of the tendon only – e.g. extensor digitorum longus
bipennate = two sides of the tendon – e.g. rectus femoris
multipennate = arranged in many places around central tendon – e.g. deltoid muscle
Facial Expression
Facial Expression
*cutaneous muscles – skeletal muscles attached to skin - confined primarily to face and neck
allow skin to twitch to remove irritants (e.g. insects)
important in non-verbal communication
*skin around eyes and eyebrows orbicularis oculi – closes eyelids *movement of lips and skin around lips -closing and puckering lips: orbicularis oris – closes lips buccinator – flattens cheek -smiling: zygmaticus major and minor – elevate and abduct upper lip -sneering: levator labii superioris – elevates upper lip -pouting or frowning: depressor labii inferioris – depresses lower lip mentalis- wrinkles chin and protrudes lower lip
Facial Expression:
Cutaneous muscles
Cutaneous muscles – skeletal muscles attached to skin - confined primarily to face and neck
allow skin to twitch to remove irritants (e.g. insects)
important in non-verbal communication
Facial Expression:
Skin around eyes and eyebrows
*skin around eyes and eyebrows
orbicularis oculi – closes eyelids
Facial Expression:
movement of lips and skin around lips
*movement of lips and skin around lips
-closing and puckering lips:
orbicularis oris – closes lips
buccinator – flattens cheek
-smiling: zygmaticus major and minor – elevate and abduct upper lip -sneering: levator labii superioris – elevates upper lip -pouting or frowning: depressor labii inferioris – depresses lower lip mentalis- wrinkles chin and protrudes lower lip
Mastication = chewing
Mastication = chewing
forceful closing of mouth = elevators of mandible
brings mandibular teeth forcefully against maxillary teeth to crush food
some of the strongest muscles of the body:
**temporalis – elevates and retracts mandible
**masseter – elevates and protracts mandible
Muscle of Mastication = chewing
- *temporalis – elevates and retracts mandible
* *masseter – elevates and protracts mandible
Tongue Movements
Tongue Movements
important in mastication and speech:
moves food around mouth
holds food in place
pushes food up to palate and back toward pharynx to initiate swallowing
changes shape to modify sound during speech
**intrinsic muscles = within the tongue itself – change shape of tongue **extrinsic muscles = outside of tongue but attach to it change shape of tongue, and move it – up, down, out, back
Muscles of anterior neck and throat used in swallowing
Muscles of anterior neck and throat used in swallowing
involves muscles of the hyoid, soft palate, pharynx and larynx
**suprahyoid muscles allow mandible to depress when hyoid is fixed by infrahyoid group
**infrahyoid group – elevate the larynx when suprahyoid group is fixed
during swallowing – food is forced into the esophagus
Head and Neck Muscles
Head and Neck Muscles
Movement of head and neck by muscles that attach to skull and bones in the neck region
Rotation and lateral flexion of the neck:
**sternocleidomastoid = prime mover of lateral group
one contracting laterally flexes head to same side and rotates head and neck to opposite side
both contracting together flex neck
**scalenes – origin = cervical vertebrae; insertion = first and second ribs
Extension, rotation and lateral flexion of the neck posterior capitus group
Head and Neck Muscles
Movement of head and neck by muscles that attach to skull and bones in the neck region
Rotation and lateral flexion of the neck:
**sternocleidomastoid = prime mover of lateral group
one contracting laterally flexes head to same side and rotates head and neck to opposite side
both contracting together flex neck
**scalenes – origin = cervical vertebrae; insertion = first and second ribs
Head and Neck Muscles
Movement of head and neck by muscles that attach to skull and bones in the neck region
Extension, rotation and lateral flexion of the neck
posterior capitus group
Trunk muscle functions:
Trunk Muscles
move the vertebral column, muscles involved in breathing, abdominal wall, and pelvic floor
Trunk muscle functions: muscles moving the vertebral column
muscles moving the vertebral column
*extend, laterally flex and rotate vertebral column
*superficial group most extend from vertebrae to the ribs: very strong to maintain posture **erector spinae – group of muscles on either side of spine that extend the head, neck and vertebral column • spinalis – upper portion • longissimus – middle portion • iloiocostalis – lowest portion *deep group extend between spinous and transverse processes of individual vertebrae
Trunk muscle functions: Muscles of respiration
Muscles of respiration
involved in breathing
**external intercostals – elevates ribs during quiet inspiration
**internal intercostals – depresses ribs during forced expiration
**diaphragm = main muscle of inspiration – flattens to depress floor of thorax
Trunk muscle functions: Abdominal wall
Abdominal wall
*crossing pattern of anterior abdominal muscles creates strong anterior wall:
holds in and protects abdominal viscera
*contractions **flexes and rotate the vertebral column
when vertebral column fixed aid in:
• forced expiration
• vomiting
• defication
• urination
• childbirth
*linea alba = located in the midline from the xiphoid process to the pubis = **dense connective tissue
*rectus abdominus – on either side of linea alba and covered by rectus sheath
tendinosus intersections cross at several places producing “six-pack”
*external obliques – superficial lateral abdominal muscle
*internal obliques – middle lateral abdominal muscle
*transversus abdominis – deepest abdominal muscle
Abdominal wall
*linea alba = located in the midline from the xiphoid process to the pubis = **dense connective tissue
*rectus abdominus – on either side of linea alba and covered by rectus sheath
tendinosus intersections cross at several places producing “six-pack”
*external obliques – superficial lateral abdominal muscle
*internal obliques – middle lateral abdominal muscle
*transversus abdominis – deepest abdominal muscle
Pelvic floor and Perineum
Pelvic floor and perineum
inferior opening of pelvis closed by **pelvic diaphragm (muscular wall)
anus and urogenital openings penetrate wall
**perineum = inferior to pelvic floor
contains muscles for enclosing urogenital triangle involved in erection and support of pelvic floor, and external anal sphincter that closes anal opening
Upper Limb Muscles
Includes muscles that move the scapula, arm, forearm and hand
Upper Limb Muscles:
Scapular movements
Scapular movements
*anterior muscles: **serratus anterior, pectoralis minor, subclavius
*posterior muscles: **trapezius, levator scapulae, rhomboids (major and minor)
move scapula - permits wide range of movements of upper limbs
hold scapula in place (fixators) when arm muscle contract
Upper Limb Muscles:
Arm movements
Arm movements
attached to thorax by several muscles:
**pectoralis major = **adducts and medially rotates arm
**deltoid muscle –prime mover to **abduct the arm
**latissimus dorsi – prime mover of **arm extension, adducts and medially rotates arm
**rotator cuff muscles – **hold head of humerus to glenoid cavity of scapula
• infraspinatus, supraspinatus, subscapularis, teres minor
• form cup or cuff over proximal humerus
• damage involves damage to one or more of muscles or their tendons
• **laterally and medially rotate and abduct and adduct arm
Upper Limb Muscles:
Forearm movements
Forearm movements
include: extension and flexion of the elbow, and supination and pronation of the forearm and hand
**triceps brachii = main mass visible on posterior aspect of arm, **forearm extensor:
tennis elbow (lateral epicondylitis)– repetitive and forceful use of forearm extensor muscles,
**biceps brachii = anterior aspect of arm, **flexes and supinates forearm and hand
branchialis = deep to biceps brachii – seen as mass on medial and lateral sides of arm, flexes elbow
brachioradialis = bulge on anterolateral side of forearm just distal to elbow, flexes elbow; origin: lateral supracondylar ridge of humerus; insertion: styloid process of radius
**supinator (Fig. 10.16) – supinates forearm and hand
**pronator teres and quadratus – pronates forearm and hand
Upper Limb Muscles:
Wrist, hand and finger movements
Wrist, hand and finger movements
**extrinsic hand muscles – are in the forearm but have tendons that extend into wrist
**anterior forearm muscles = flexion of wrist and fingers (Fig. 10.16)
**posterior forearm muscles = extension of wrist and fingers (Fig. 10.17)
extensor carpi radialis longus, brevis and ulnaris – extend wrist
extensor digitorum – extends fingers
intrinsic hand muscles (Fig. 10.19) = muscles entirely within the hand
-adduction and abduction of fingers
Lower Limb Muscles
Lower Limb Muscles
involves muscles that provide movement of the hip and thigh, leg, ankle, foot and toes
Lower Limb Muscles
Anterior, posterolateral and deep muscles that originate on coxal bone and insert onto femur
**anterior muscles = **iliopsoas – prime mover that flex thigh
**posterolateral muscle – all **adbuct thigh:
**gluteus maximus – makes most of the mass viewed as buttocks
laterally rotates thigh and maximum force = extension of thigh
gluteus medius – superior and lateral to gluteus maximus, common site for injections
gluteus minimus – deep to gluteus medius:
abduct and medially rotate thigh
**tensor fasciae latae – smaller muscle portion proximally that becomes large aponeurosis (iliotibial tract) distally:
medially rotates thigh and **stabilizes femur on tibia when standing
Thigh muscles organized into compartments
Thigh muscles organized into compartments
*anterior compartment muscles – flex thigh and/or extend leg
* medial compartment muscles – all adduct, flex and medially rotate thigh * posterior compartment muscles (hamstrings) – cross two joints: hip and knee and extend thigh and flex the leg
Thigh muscles organized into compartments:
Anterior compartment
Anterior compartment muscles **flex thigh and/or extend leg
**quadriceps femoris – common insertion: patella and tibial tuberosity via the petallar ligament and except for rectus femoris are **all leg extenders:
• vastus lateralis – injection site on lateral side of thigh
• rectus femoris –lies in center of the group of muscles - allows thigh flexion and leg extension
• vastus intermedius – lies deep to rectus femoris
• vastus medialis – most medial of group
**Sartorius – longest muscle of body • crosses two joints – allows **thigh and knee flexion, abducts and laterally rotates thigh
Thigh muscles organized into compartments:
Medial compartment
Medial compartment muscles – all **adduct, flex and medially rotate thigh pectinius adductor brevis adductor longus adductor magnus **gracilis
Thigh muscles organized into compartments:
Posterior compartment
Posterior compartment muscles (hamstrings) – cross two joints: hip and knee and **extend thigh and flex the leg
**biceps femoris –laterally rotates leg
semimembranosus –medially rotates leg
semitendinosus - medially rotates leg
Ankle, foot and toe movements:
Have extrinsic and intrinsic muscles groups
Extrinsic muscles = muscles associated with compartments of the leg that move the ankle and foot
Ankle, foot and toe movements:
Extrinsic muscles and
Intrinsic muscles
Extrinsic muscles = muscles associated with compartments of the leg that move the ankle and foot: #Anterior compartment = extensor muscles – allow dorsiflexion, inversion or eversion of foot, extension of toes #Lateral compartment = mainly **eversion of foot and aid in **plantar flexion, tendons seen on the lateral side of the ankle #Posterior compartment = superficial muscle group –insert via common tendon calcaneal (Achilles) tendon and allow plantar flexion of foot
Intrinsic muscles = muscles within the foot itself – **flex, extend, abduct and adduct toes
Ankle, foot and toe movements:
Extrinsic muscles - Anterior compartment
Anterior compartment = **extensor muscles – allow dorsiflexion, inversion or eversion of foot, extension of toes
• extensor digitorum longus
• extensor halluces longus
• tiabialis anterior
• fibularis tertius
• **shin splits = pain associated with anterior compartment associated with muscle stress, inflammation, stress fractures of tibia – causes include running with unsupportive shoes or on hard surface, increasing activity too quickly
Ankle, foot and toe movements:
Extrinsic muscles - Lateral compartment
Lateral compartment = mainly **eversion of foot and aid in plantar flexion, tendons seen on the lateral side of the ankle
• fibularis brevis
• fibularis longus
Ankle, foot and toe movements:
Extrinsic muscles - Posterior compartment
Posterior compartment
Superficial muscle group –insert via common tendon **calcaneal (Achilles) tendon and allow **plantar flexion of foot **gastrocnemius – crosses two joints so also **flexes the knee: together with soleus form the bulk of the calf soleus plantaris Deep muscle group – **plantar flexion and inversion of foot, flex toes flexor digitorum longus – origin: tibia, insertion: four lateral toes flexor halluces longus – origin: fibula, insertion: distal phalynx of great toe tibialis posterior – origin: tibia, insertion: navicular, cuneiforms, cuboid, and second to fourth metatarsals
Ankle, foot and toe movements:
Intrinsic muscles
Intrinsic muscles = muscles within the foot itself – **flex, extend, abduct and adduct toes
muscles covered with thick fascia and plantar aponeurosis
**plantar fasciitis = inflammation of plantar aponeurosis resulting in pain over the heel and along the medial-inferior side of the foot
• cause – running on hard surface wearing poorly fitting or worn-out shoes
