Muscular System - Anatomy and Physiology - Laboratory Flashcards
human body contains ________________ skeletal muscles,
more than 600
the major organs of the muscular system
600 skeletal muscles
4 groups of the body’s major muscles
- muscles of the head and neck
- muscles of the trunk
- muscles of the upper limb
- muscles of the lower limb
During movements, one of the bones ___________________________________ while the other bone _________________.
remains relatively stationary; moves
site of attachment of a muscle’s tendon to
the stationary bone
origin
the site of attachment to the moveable bone
insertion
During muscle contraction, the _____________ moves toward the origin.
insertion
thicker middle region of the muscle between the origin and the insertion
belly
refers to the identity of the nerve that stimulates it to contract, producing that muscle’s action
innervation
A muscle’s innervation refers to the identity of the nerve that stimulates it to contract, producing that muscle’s
action
Skeletal muscles are innervated by two groups of nerves:
cranial nerves and spinal nerves
arise from the base of the brain and emerge through the foramina of the skull
cranial nerves
sensory nerves that transmit nerve impulses from the sensory receptors of the eye, ear, and nose to the brain
cranial nerves
arise from the spinal cord and emerge
through the intervertebral foramina
spinal nerves
these nerves innervate skeletal muscles below the neck
spinal nerves
how many cranial nerves?
12
how many pairs of spinal nerves?
31
are usually the result of the actions of several skeletal muscles acting as a group
Movements
Muscles can be classified into four functional groups:
- prime movers (agonist)
- antagonists
- synergists
- fixators
is the muscle that is most responsible for producing a particular movement, termed that muscle’s action
prime movers (agonist)
is a muscle that opposes the action of a prime mover.
antagonists
during flexion of the elbow, the biceps brachii serves as the ______________, and the triceps brachii serves as the _________________
prime mover; antagonist
These two muscles constitute an ___________________ that acts on the opposite sides of a bone or joint.
antagonistic pair
is a muscle that aids a prime mover and is usually located close to it
synergist
can stabilize a joint, prevent unwanted movements, or add extra force so that the action of the prime mover is more coordinated and specific
synergist
Consider the role of the wrist extensor muscles as ____________________ in flexion of the fingers.
synergists
is a muscle that stabilizes the origin of the prime mover so that the prime mover can act more efficiently.
fixator
“fixes” a bone—that is, it holds it steady
fixator
Skeletal muscles are named based on one or more of the
following seven criteria:
- location
- shape,
- principal action
- relative size
- number of origins
- locations of origins and insertions
- direction of muscle fibers
overlies the brachium (arm)
brachialis
is roughly triangular (delta = triangle)
deltoid
The muscles of the head and neck can be divided into four
functional groups:
- the muscles of facial expression
- the muscles of mastication (chewing) and tongue movements
- the muscles that move the hyoid bone and larynx
- the muscles that move the head and neck
The muscles that enable us to communicate emotions through facial expression are located just deep to the skin in the
scalp, face, and neck
All facial muscles are innervated by the
facial nerve (CN VII)
is a bipartite (two-part) muscle with two bellies (an occipital belly and a frontal belly) connected by the epicranial aponeurosis
epicranius
two bellies of epicranius
- frontal belly (frontalis)
- occipital belly (occipitalis)
overlies the frontal bone and raises the eyebrows (as when you are surprised)
frontal belly (frontalis)
draws the scalp back toward the posterior neck
occipital belly (occipitalis)
encircles the eye and closes it during blinking
orbicularis oculi
originate on the zygomatic bone and draw the lateral
corners of the mouth upward (as in smiling)
zygomaticus major and zygomaticus minor
is a narrow muscle located inferior and lateral to the zygomaticus major.
risorius
It pulls the lips laterally and is considered to be a synergist of the zygomaticus muscles.
risorius
is a thin, horizontal cheek muscle that lies deep to the masseter muscle
buccinator
it compresses the cheeks during whistling, blowing, or sucking on a straw.
buccinator
This muscle is well developed in nursing infants
buccinator
is a circular muscle that closes and protrudes the lips as in kissing.
orbicularis oris
depresses the lower lip
depressor labii inferioris
raises the upper lip
levator labii superioris
elevates and protrudes the lower lip and pulls the skin of the chin up as in pouting
mentalis
is an unpaired, thin sheetlike superficial neck muscle that depresses the mandible and draws the outer part of the lower lip inferiorly and posteriorly, as in pouting.
platysma
Raises eyebrows; wrinkles skin of forehead horizontally
Frontalis
Pulls scalp posteriorly
Occipitalis
Pulls eyebrows inferiorly and medially (as in squinting)
Corrugator supercilii
Closes eye; pulls skin around the eyes, as in blinking and winking
Orbicularis oculi
Elevates the upper lip; everts and furrows upper lip (as in sneering)
Levator labii superioris
Raises lateral portion of the upper lip to expose
upper teeth (as in smiling)
Zygomaticus minor
Pulls the angle of the mouth superiorly and laterally (as in smiling or laughing)
Zygomaticus major
Pulls the angle of the mouth laterally to make a closed-mouth smile
Risorius
Closes and protrudes lips (as in puckering the lips for a kiss
Orbicularis oris
Draws corners of the mouth inferiorly (unhappy face)
Depressor anguli oris
Protrudes lower lip (sad or pouting expressions)
Depressor labii inferioris
Protrudes the lower lip and chin for drinking and “doubtful” expression
Mentalis
Helps manipulate food during chewing and expels air through pursed lips (as in blowing a trumpet)
Buccinator
Lowers lower lip and opens mouth by depressing the
mandible
Platysma
The four muscles of mastication produce chewing movements by depressing and elevating the mandible,
and all are innervated by
trigeminal nerve (CN V)
- is a prime mover of jaw closure and biting.
- short and thick
masseter
elevates the mandible and functions as an agonist to the masseter, fan-shaped
temporalis
depresses and protracts the mandible and moves it from side to side
lateral pterygoid
elevates the mandible and moves it from side to side
medial pterygoid
Elevates the mandible
Masseter
Elevates and retracts the mandible
Temporalis
Elevates and protracts the mandible; assists in lateral movements to grind food
Medial pterygoid
Protracts and depresses the mandible; lateral movements to grind food
Lateral pterygoid
involved in mastication, detection of taste, and deglutition (swallowing)
tongue
Muscles that control the tongue are classified as
- intrinsic
- extrinsic
originate and insert within the tongue and change the shape of the tongue
intrinsic
originate outside the tongue and insert onto it
extrinsic
The three extrinsic tongue muscles
- genioglossus
- hyoglossus
- styloglossus
depresses the tongue and thrusts it anteriorly (protraction)
genioglossus
also depresses the tongue
hyoglossus
elevates the tongue and draws it posteriorly (retraction)
styloglossus
glossus
tongue
The muscles that move the hyoid bone and the larynx consist of two groups:
suprahyoid and infrahyoid muscles
Protrudes tongue
Genioglossus
Depresses tongue
Hyoglossus
Retracts and elevates tongue
Styloglossus
originate superior to the hyoid bone and elevate it, the floor of the oral cavity, and the tongue during swallowing.
suprahyoid muscles
Among the suprahyoid muscles are
- digastric
- mylohyoid
- stylohyoid
consists of an anterior belly and a posterior belly united by a central tendon and which depresses the mandible and elevates the hyoid bone during swallowing and talking
digastric
elevates the hyoid bone and the base of the tongue during swallowing
mylohyoid
elevates the hyoid bone
stylohyoid
originate inferior to the hyoid bone and depress it and the larynx during swallowing and talking.
infrahyoid muscles
Among the infrahyoid muscles are the:
- sternohyoid
- sternothyroid
- thyrohyoid
depresses the hyoid bone and larynx during swallowing
sternohyoid
which depresses the larynx
sternothyroid
depresses the hyoid bone
thyrohyoid
Elevates and retracts the hyoid and floor of the mouth during swallowing
Stylohyoid
Elevates hyoid and floor of mouth, assisting tongue to push food toward the pharynx
Mylohyoid
Elevates and protracts hyoid
Geniohyoid
Depresses hyoid bone and larynx
Sternohyoid
Depresses larynx and hyoid bone
Sternothyroid
Depresses and retracts hyoid bone
Omohyoid
Depresses hyoid bone; may elevate larynx
Thyrohyoid
Depresses the mandible; fixator of the hyoid during
swallowing
Digastric
paired muscles that constitute the main muscles of the anterior neck
sternocleidomastoid
originates on the sternum and clavicle and inserts onto the mastoid process of the temporal bone.
sternocleidomastoid
is a bipartite muscle that extends the head; it consists of the splenius capitis and the splenius cervicis (deep to the trapezius).
splenius
are located on the lateral aspect of the neck deep to both the platysma and the sternocleidomastoid; these muscles flex the neck and also elevate ribs 1 and 2 to aid in respiration.
scalenes
Together: flex head (chin moves toward the chest); individually: flex and rotate the head toward opposite side; accessory muscles of respiration
Sternocleidomastoid
A mix of actions, depending on the fixators in play; move head laterally when contracted individually; elevate rib cage with vertebral column fixed; accessory muscles of respiration
Scalenes
Extends the head (raises head from “bowed” position); other actions covered in the section on muscles of the arm
Trapezius (superior section)
Extends the head; with other muscles, rotates the head to the same side
Splenius capitis
Extends the head and neck; rotates the upper cervical vertebrae to the same side as the muscle that is contracting
Splenius cervicis
Extends the head; with other muscles, rotates the head to the opposite side from the muscle that is contracting
Semispinalis capitis
The muscles of the trunk include:
- muscles of the vertebral column
- muscles of respiration
- muscles of the abdominal wall
- muscles that act on the pectoral girdle
play major roles in moving the limbs
superficial back muscles
The muscles associated with the vertebral column include the:
- erector spinae group
- transversospinal group
- quadratus lumborum
extends and flexes the vertebral column laterally, consists of three separate muscle groups that run between the sacrum and the posterior surface of the skull on either
side of the vertebral column
erector spinae group
three muscles of erector spinae group
- spinalis,
- longissimus
- iliocostalis
spinalis and longissimus groups each consist of a
- capitis muscle
- cervicis muscle
- thoracis muscle
iliocostalis group consists of a
- cervicis muscle
- thoracis muscle
- lumborum muscle
which also extends the vertebral column, is a similar but deeper group of muscles
transversospinal group
group consisting of capitis, cervicis, and thoracis portions; the multifidus muscle; and the rotatores muscle
semispinalis
flexes the vertebral column laterally
quadratus lumborum
A major function of the muscles of the trunk is
respiration
separates the thoracic and abdominopelvic cavities, and the intercostal muscles
diaphragm
The most important muscle of inspiration is the dome-shaped
diaphragm
innervated by the phrenic nerve.
diaphragm
The fibers of the 11 pairs of ______________________ run obliquely (inferiorly and anteriorly) between the ribs
external intercostals
which pull the ribs toward one another and elevate the rib cage, are innervated by the intercostal nerves.
external intercostals
The fibers of the 11 pairs of the ________________________ run deep to and at right angles to those of the external intercostal muscles and serve as antagonists to the external intercostals.
internal intercostals
depress the rib cage and draw the ribs together, and they are innervated by the intercostal nerves
internal intercostals
Flattens to lower the floor of the thoracic cavity to increase volume and decrease pressure, thereby causing inspiration (inhalation)
Diaphragm
Elevates the rib cage, spreading the ribs, assisting inspiration
External intercostal muscles
Depresses the rib cage, pulling ribs closer together, assisting expiration
internal intercostal muscles
support and protect the organs within the abdominal cavity;
abdominal muscles
they also flex the vertebral column and rotate and laterally flex the trunk.
abdominal muscles
flexes the vertebral column
rectus abdominis
also flex the vertebral column, and they also compress the abdominal wall.
external oblique and internal oblique
compresses the abdominal contents
transversus abdominis
All four abdominal muscles are innervated by the
intercostal nerves
support and position the scapula and the clavicle
muscles that act on the pectoral girdle
muscles that act on the pectoral girdle stabilize the shoulder joint by reinforcing the articulation between the
humerus and the scapula
Flexes the trunk; with the vertebral column fixed, compresses abdominal cavity
Rectus abdominis
Flexes and laterally bends the trunk; with the vertebral column fixed, compresses abdominal cavity
External oblique
Flexes and laterally bends the trunk; compresses abdominal
cavity
internal oblique
Compresses abdominal cavity
Transversus abdominis
The muscles of the upper limb include
- muscles that move the arm
- muscles that move the forearm
- muscles that move the wrist, hand, and digits
large, superficial, fanshaped muscle that covers the superior portion of the chest and is a prime mover of arm flexion; it also adducts and medially rotates the arm.
pectoralis major
is a superficial triangular shoulder muscle and a prime mover of arm abduction.
deltoid
broad flat muscle located in the lumbar region, is a prime mover of arm extension. It also adducts and medially rotates the arm.
latissimus dorsi
thick rounded muscle that lies inferior to the teres minor and it extends, medially rotates, and adducts the humerus.
teres major
small cylindrical muscle that flexes and adducts the humerus
coracobrachialis
lies deep to the trapezius and is one of the four rotator cuff muscles.
supraspinatus
is a rotator cuff muscle that rotates the humerus laterally and stabilizes the shoulder
infraspinatus
is a rotator cuff muscle that laterally rotates the humerus and stabilizes the shoulder
teres minor
is a rotator cuff muscle that medially rotates the humerus and stabilizes the shoulder
subscapularis
originate on the humerus, cross over the elbow joint, and insert onto the ulna and/or radius
muscles that move the forearm
is the only muscle on the posterior side of the arm; large, three-headed
triceps brachii
it is a powerful forearm extensor
triceps brachii
two-headed __________________flexes and supinates the forearm
biceps brachii
superficial ___________________ of the lateral forearm acts as a synergist in forearm flexion
brachioradialis
lies deep to the biceps brachii muscle and flexes the forearm
brachialis
pronates the forearm and is also a weak forearm flexor.
pronator teres
is a superficial forearm muscle named for both its proximity
to the radius and its actions (wrist flexion and abduction).
flexor carpi radialis
is a weak wrist flexor.
palmaris longus
is named for both its proximity to the ulna and its actions
(wrist extension and adduction).
extensor carpi ulnaris
extend and abduct the wrist
extensor carpi radialis longus and the extensor carpi radialis brevis
on the posterior surface of the forearm extends the digits (fingers).
extensor digitorum
flexes and adducts the wrist.
flexor carpi ulnaris
Flexes and adducts the arm; rotates arm medially
Pectoralis major
adducts and extends the arm; rotates arm medially
Latissimus dorsi
abducts the arm; secondarily flexes and extends arm
Deltoid
adducts, extends, and rotates arm laterally
Teres major
Flexes and adducts the arm
Coracobrachialis
Assists abduction; holds the humerus and stabilizes
shoulder joint
Supraspinatus
Laterally rotates the humerus; stabilizes shoulder joint
infraspinatus
Laterally rotates the humerus; stabilizes shoulder joint
Teres minor
adducts and rotates the humerus medially; stabilizes shoulder joint
Subscapularis
Flexes the elbow; supinates the forearm
Biceps brachii
Flexes the elbow (prime mover)
Brachialis
Flexes the elbow (synergist)
Brachioradialis
Extends the elbow
Triceps brachii
Assists extension of the elbow
anconeus
Pronates forearm (palm posterior)
Pronator teres
Flexes wrist (bends wrist toward anterior forearm); abducts hand
Flexor carpi radialis
Flexes wrist; tenses dense connective tissue in palm of hand
Palmaris longus
Flexes wrist; adducts hand
Flexor carpi ulnaris
Flexes fingers; flexes wrist
Flexor digitorum superficialis
Flexes thumb
Flexor pollicis longus
Flexes fingers; flexes wrist
Flexor digitorum profundus
Pronates forearm
Pronator quadratus
Extends wrist; abducts hand
Extensor carpi radialis longus
Extends wrist; abducts hand
Extensor carpi radialis brevis
Extends fingers; extends wrist
Extensor digitorum
Extends little finger
Extensor digiti minimi
Extends wrist; adducts hand
Extensor carpi ulnaris
Supinates forearm (palm anterior)
Supinator
Abducts and extends thumb
abductor pollicis longus
Extends thumb (“thumbs up” motion)
Extensor pollicis longus
Extends thumb
Extensor pollicis brevis
Extends index finger
Extensor indicis
The muscles of the lower limb include:
- muscles that move the thigh
- muscles that move the leg
- muscles that move the ankle, foot, and digits
Among the muscles that move the thigh is the
iliopsoas
two muscles of iliopsoas
-psoas major
- iliacus
Butchers refer to this muscle as the tenderloin.
psoas major
is the most superficial and the most prominent of the three gluteal muscles that form the buttocks.
gluteus maximus
It is a powerful extensor of the thigh.
gluteus maximus
lies deep to the gluteus maximus and abducts and medially rotates the thigh.
gluteus medius
it is a common site for intramuscular injections
gluteus medius
the smallest of the three gluteal muscles, lies deep to the gluteus medius
gluteus minimus
it acts as an agonist to the gluteus medius in abducting and medially rotating the thigh
gluteus minimus
located on the lateral surface of the thigh, flexes and abducts the thigh
tensor fasciae latae
pear-shaped muscle that lies inferior to the gluteus minimus and laterally rotates and abducts the thigh
piriformis
a medial thigh muscle, belongs to the adductor group, which adducts, flexes, and medially rotates the thigh.
adductor longus
The anterior part of the __________________, another medial thigh muscle, adducts, medially rotates, and flexes the thigh, whereas the posterior part is a thigh extensor.
adductor magnus
is a medial thigh muscle that adducts and medially rotates the thigh.
adductor brevis
small flat muscle that overlies the adductor brevis and
adducts, flexes, and medially rotates the thigh.
pectineus
long, thin, superficial muscle and is a medial thigh muscle that adducts the thigh and flexes and medially rotates the leg. long, thin, superficial
gracilis
is on the anterior aspect of the thigh and is the most superficial of the four muscles that belong to the group known as the quadriceps femoris, which extends the leg.
rectus femoris
on the lateral aspect of the thigh, is a member of the quadriceps femoris that extends the knee.
vastus lateralis
a member of the quadriceps femoris on the medial aspect of the thigh, extends the knee.
vastus medialis
a member of the quadriceps femoris deep to the rectus femoris, extends the knee.
vastus intermedius
forms a band across the thigh from the ilium to the medial side of the tibia
sartorius
it flexes, abducts, and laterally rotates the thigh.
sartorius
This is the muscle you use to sit cross-legged.
sartorius
is one of three muscles on the posterior aspect of the thigh that collectively are commonly called the hamstrings, a name derived from an old butchers’ practice of curing pork thighs in a smokehouse by hanging them from their tendons (their hamstrings).
biceps femoris
a hamstring muscle medial to the biceps femoris, flexes the leg at the knee joint.
semitendinosus
is a hamstring muscle that lies deep to the semitendinosus and flexes the leg at the knee joint.
semimembranosus
a superficial anterior leg muscle just lateral to the anterior crest of the tibia
tibialis anterior
It inverts the foot and is a prime mover of dorsiflexion
tibialis anterior
which is lateral to the tibialis anterior, is a prime mover of toe extension
extensor digitorum longus
a superficial lateral muscle that overlies the fibula, produces plantar flexion and everts the foot.
fibularis longus
a superficial muscle that forms the bulk of what is commonly called the calf muscle, produces plantar flexion;
gastrocnemius
because it crosses the knee joint, it can flex the knee when the foot is dorsiflexed.
gastrocnemius
named for its resemblance to a sole (a type of flat fish), is located deep to the gastrocnemius and produces plantar flexion of the foot at the ankle joint.
soleus
which is deep to the soleus, is a prime mover of foot inversion and produces plantar flexion of the foot at the ankle joint.
tibialis posterior
runs medial to the tibialis anterior muscle; it produces plantar flexion, inverts the foot, and flexes the toes
flexor digitorum longus
