Muscles Flashcards
Skeletal muscles
under conscious control - a person can decide to use these muscles to complete an action.
peripheral nerves
carry the signal from the central nervous system (brain and spinal cord) to a specific muscle destination to provide movement.
motor actions
messages from the central nervous system to a muscle
sensation or sensory input
nerves also carry information from the external environment to the central nervous system
spinal nerves
combine to form complex networks of peripheral nerves throughout the body.
tendons
connective tissue that connects muscle to bones
ligaments
connective tissue that connects bone to bone
origin
the bony site of attachment that is stationary during movement
insertion
the insertion of a muscle is the bony site of attachment that is moved by muscle contraction
action
the action of a muscle is what effect is produced by the muscle contraction – for example the triceps are the primary extensor of the forearms
innervation
the peripheral nerve that supplies a muscle with the message from the brain
ex. innervation of the biceps brachii is the muscleocataneous nerve
orbicularis oculi
Action: eye closure
Innervation: facial nerve (CN IIV)
orbicularis oris
Action: mouth closure
Innervation: Facial Nerve (CN IIV)
Zygomaticus major/Minor
Action: Pull the lips upward
Innervation: Facial nerve (CN IIV)
Risorius
Action: Pull the corner of the mouth posteriorly (grin or grimace
Innervation: Facial nerve ( CN IIV)
Frontalis
Action: raise eyebrows
Innervation: Facial Nerve (CN IIV)
Buccinator
Action: compress cheeks
Innervation: Facial nerves (CN IIV)
Masseter
Action: Jaw Closure
Innervation: trigeminal nerve
Temporalis
Action: elevates mandible and closes jaw
Innervation: trigeminal nerve
lateral flexion
AKA side flexion- side bending of the neck which refers to moving one of the ears to the same side shoulder
Neck flexion
refers to moving the chin towards the sternum
bilaterally and unilaterally
there are several muscles that have differing actions
if acting together on both sides- bilaterally
acting on one side- unilaterally
Semispinalis capitis
Action: bilateral extend head
Unilateral -laterally flexes neck to the same side
Origin- articular process of inferior cervical process and transverse of superior thoracic vertebrae
Insertion: occipital bone
Innervation: Spinal nerves
Sternocleidomastoid
Action: bilateral neck flexion
unilateral- turn face to opposite side
Origin: sternal end of clavicle and manubrium
Insertion: Mastoid region of the skull
Innervation: Accessory nerve
Splenius capitis
Action: bilateral extend head
unilateral -laterally flexes neck to the same side
Origin: spinous process/ ligaments of inferior cervical vertebrae
Insertion: mastoid process, occipital bone of skull
Innervation: cervical spinal nerves
Longissimus crevicis
Action: bilateral extend head
unilateral - laterally flexes neck to same side
Origin: Transverse processes of superior thoracic vertebrae
insertion: transverse process of middle and superior cervical vertebrae
Innervation: cervical and thoracic spinal nerves
Longissimus thoracis
Origin: Transverse processes of all thoracic and lumbar vertebrae
Insertion: Transverse processes of all thoracic vertebrae
Action: bilateral extension of spine
unilateral lateral flexion of spine
Innervation: thoracic and lumbar spinal nerves
Thyrohyoid
Origin: thyroid cartilage of the pharynx
Insertion: Hyoid bone
Action: elevates thyroid, depresses hyoid bone
Innervation: hypoglossal nerve
Scalenes (anterior, middle, posterior)
Origin: Transverse processes
of C2-C7
Insertion: first and second ribs
Action: elevates ribs 1-2
Innervation: cervical spinal nerves
Flexion of spine
refers to forward bending of the trunk (Cat stretch)
Extension of spine
refers to backward bending
Spinal movement
flexion and extension as well as lateral flexion and rotation (movement around an axis)
Spinalis
medial column of erector spine
contains spinalis thoracis, spinalis cervicis, spinalis capitits
Longissimus
Intermediate column of the erector spine -
contains three divisions - longissimus thoracis, longissimus cervicis, longissimus capitits
Iliocostalis
lateral column of the erector spine
consists of three divisions - iliocostalis lumborum, iliocostalis thoracis, illiocostalis cervicis
Rectus abdominus
Origin: Pubic crest, pubic symphysis
Insertion: cartilages of ribs 5-7, xiphoid process
Action: flexion of the spine, compression of abdominal viscera,
Innervation: spinal nerves (T7-T12
External oblique
Origin: Sternum (ribs 5-12)
Insertion: linea alba, iliac crest
Action:
Bilaterally: flexion of spine, compress the abdomen
Unilaterally- flexes trunk to the same side, rotates to the opposite side
Innervation: lower intercostal, ilioinguinal nerves
Internal Oblique
Origin: iliac crest, lumbodorsal fascia
Insertion: inferior ribs, linea alba
Action: Compresses abdomen, depresses ribs, flexes spine
Innervation: lower intercostal, ilioinguinal nerves
Transverse abdominas
deep to internal oblique
Origin: lateral lingual ligament, inner iliac crest
Insertion: linea alba, pubis
Action: compression of abdomen
Innervation: first lumbar nerve ( T7-L1), iliohypogastric (T12-L1), ilioinguinal (T2-L1)
Diaphragm
Origin: cartilage of ribs 7-12, xiploid process, lumbar vertebrae
Insertion: anterior longitudinal ligament (vertebral column)
Action: Expands thoracic cavity, compresses abdominal cavity
Innervation: phrenic nerve (C3-5)
Internal Intercostals
Origin: superior border of ribs 2-12
Insertion: inferior of ribs above ribs 1-11
Action: depresses ribs (forced exhalation)
Innervation: intercostal nerves
External intercostals
Origin: lower border of ribs 1-11
Insertion: upper border of ribs below 2-12
Action: elevates ribs (normal inspiration)
Innervation: Intercostal nerves
trapezius (upper, middle, lower)
Origin: Occipital lobe, spinous process
Insertion: lateral clavicle, acromion, and scapula spine of scapula
Action: rotation, retraction, elevation and depression of the scapula, extends neck and stabilizes shoulder
Innervation: Accessory nerve
Levator Scapulae
Origin: Transverse process of C1-C4
Insertion: medial border of scapula
Action: elevates scapula
Innervation: dorsal scapular nerve
Rhomboid (Major and Minor)
Origin: Spinous process (minor C7- T1, major T2-5)
Insertion: medial border of scapula
Action: retraction of scapula
Innervation: dorsal scapular nerve
Pectoralis Minor
Origin: ribs 3-5
Insertion: coracoid process of scapula
Action: elevates ribs, draws scapula down and medially
Innervation: medial pectoral nerve
Serratus Anterior
Origin: upper 8-9 ribs
Insertion: medial border of scapula
Action: protraction of scapula
Innervation: long thoracic nerve
Deltoid (anterior, posterior, middle)
Origin: Clavicle and scapula
Insertion: deltoid tuberosity of humerus
Action: abduction of shoulder (whole muscle)
Innervation: axillary nerve
Pectoralis major
origin: ribs 2-6, body of the sternum
Insertion: greater tubercle of the humerus
Action: flexion, adduction of medial rotation at shoulder
Innervation: pectoral nerves
Supraspinatus
above spine of scapula
Origin: Supraspinatus fossa of scapula
Insertion: greater tubercle of humerus
Action: abduction at the shoulder
Innervation: Subscapular nerve
Infaspinatus
below spine of scapula
origin: infraspinatus fossa of scapula
insertion: greater tubercle of humerus
action: lateral rotation of shoulder
innervation: subscapular nerve
Teres Minor
Part of rotator cuff
Origin: lateral border of scapula
insertion: greater tubercle of humerus
Action: lateral rotation at shoulder
Innervation: axillary nerve
Teres Major
Not part of rotator cuff
Origin: inferior angle of the scapula
Insertion: intertubercular groove of humerus
Action: extension, adduction, and medial rotation at the shoulder
Innervation: lower subscapular nerve
Subscapularis
along inner surface of scapula
Origin: subscapular fossa of scapula
Insertion: lesser tubercle of humerus
Action: extension, adduction, and medial rotation at the shoulder
Innervation: subscapular nerves
Latissimus Dorsi
Origin: Spinous process of inferior thoracic and lumbar vertebrae, ribs 8-12
Insertion: intertubercular of humerus
Action: extension, adduction, and medial rotation at shoulder
Innervation: thoracodorsal nerve
Coracobrachialis
Origin: Coracoid process of Scapula
Insertion: medial shaft of humerus
Action: adduction and flexion at shoulder
Innervation: musculocutaneous nerve
involuntary controlled muscle
smooth and cardiac - smooth found in the internal organs such as digestive track and blood vessels and cardiac only found in the heart
Striated muscle
found in cardiac and skeletal muscle -under microscope it appears to have stripes. Smooth muscle appears without stripes
Skeletal muscle
makes up 40 percent of body weight and is attached to bones by tendons
antagonistic pair
muscles must work in pairs because they are only able to pull - not push
They are only able to pull in the direction of their fiber orientation.
If one muscle of an antogonsitic pair bends the joint and brings the limb toward the body (flexor), the other one straightens the joint and extends the limb (extensor)
Flexion/extension
closing the joint (flexion)/ opening of the joint (straightening)
Antagonistic pair example
flexor-biceps brachii
extensor - triceps brachii
Abduction/Adduction
movement away from the midline (abduction)
Movement towards the midline (Adduction)
Antagonistic pair example
Abductor- TFL of hip
Adductor- adductor longus, adductor Magnus
Dorsiflexion/Plantarflexion
Dosiflexion- movement of toes up (flexion superiorly occurring at the subtalar (ankle) joint)
Plantarflexion -flexion inferiorly occurring at the subtalar (Ankle) joint – movement of toes down
Antagonistic pair -
dorsiflexor- tibialis anterior
plantar flexor- gastrocnemius
Pronation/supinaiton
pronation - rotation of arm so palm faces posteriorly or rotation of the foot so the sole faces laterally
supination- rotation of the wrist so the palm faces anteriorly or rotation of the foot so the sole faces medially
Antagonistic pair-
pronator- pronator teres (of forearm)
supinator- biceps brachii (of forearm)
Elevation/ Depression
Elevation: upward movement
Depression: downward movement of a structure
Antagonistic pairs:
Elevator: levator scapulae
Depressor: trapezius (lower fibers
Retraction/Protraction
Retraction-movement in a posterior direction-drawn backward
Protraction: movement in the anterior direction
Antagonist pair example:
retractor-rhomboids, trapezius
protractor: serrates anterior
muscle fibers
a whole skeletal muscle is composed of many muscle fiber bundles called myofibrils
myofibrils
muscle fibers contain thousands of myofibrils which are the contractile portions of the fibers
These are cylinder shaped and run the length of the muscle fiber
The microscope shows myofibrils have light and dark bands called striations
Light and dark bands
Myofibrils have light and dark bands under the microscope (striation) - these are formed by protein myofilaments with contractile units called sacromeres
Sacromeres
contain two types of protein myofilaments - thick protein filaments called myosin and thin filaments made of a protein called actin
Myosin and actin
when a muscle fiber contracts- the sacromeres within the myofibrils shorten – the actin (thin filaments) slide past the myosin (thick filaments) and approach one another
The movement of the actin filaments in relationship to the myosin filaments causes the muscle to shorten
Z lines
one sarcomere goes from one z line to another z line
These connect parallel bands of thin filaments
M bands
thick filaments in a sarcomere are held together by M bands
I bands
light band - appears light when stained because it only contains thin filaments
A bands
dark band - appear dark when stained because they contain thick and thin filaments – the thick bands are the reason it appears dark though
What happens when a muscle contracts?
The Z line moves closer to the center of the sarcomere at the M line
Also, the nervous system must work together with the muscular system – a nerve impulse must be sent to the muscle
Once the nerve impulse reaches the fiber acetylcholine (a neurotransmitter) is released from the motor nerve ending
Acetylcholine
this neurotransmitter binds to receptors on muscle cells, opening sodium ion channels and allows the flow of sodium to flow inside the sarcoplasm (cytoplasm of a muscle cell)
The presence of sodium ions causes an action potential to occur in the sacrolemma (cell membrane of a muscle cell)
sarcoplasm
cytoplasm of a muscle cell
sarcolemma
cell membrane of a muscle cell
sarcoplasmic reticulum
specialized type of smooth ER found in striated muscle tissue-
The action potential causes calcium ions to be released in the sarcoplasmic reticulum
cross bridges
in the presence of calcium ions, portions of the myofilaments called cross-bridges bend backward and attach to actin filaments
After attaching to the actin filaments the cross bridges bend forward and pull the actin filament is pulled along
These cross bridges attach and detach 50 -100 times as the thin filaments are pulled to the center of the sarcomere
ATP is needed for the myosin cross bridges to pull the actin filaments
What it the result of a muscle contraction
the movement of many actin filaments together
What causes a muscle contraction to cease
when nerve impulses no longer stimulate the muscle fiber – with the cessation of a muscle action potential, the calcium ions are pumped back into the Sacroplasmic reticulum by active transport – once the calcium ions return to the SER then the muscle fiber relaxes
Biceps brachii
flexors
Origin: short-head - coracoid process long head- superglenoid tubercle od scapula
Insertion: tuberosity of radius
Action: flexion at elbow and shoulder -supination
brachialis
Origin: anterior/distal surface of humerus
Insertion: tuberosity of ulna
Action: flexion at elbow
Innervation: músculocutaneous nerve and radial nerve
Brachioradialis
Origin: lateral epicondyle of the radius
Insertion: lateral aspect of the styloid process of radius
Action: Flexion at elbow
Innervation: radial nerve
Triceps
extensors
long head, lateral head, and medial head
Origin:
lateral head- superior, lateral margin of humerus
long head: margin of humerus
Insertion: lateral head-
