Anatomy of the Muscular System Flashcards
Muscle fiber
Name of a single muscle cell
Endomysium
fine layer of areolar CT that surrounds each muscle fiber (cell)
Perimysium
dense irregular CT sheet around fascicles (groups of muscle fibers)
Epimysium
dense, irregular fibrous CT that surrounds the whole muscle
What is the deep fascia
still coarser layer of dense connective tissue that binds muscles into functional groups e.g. hamstrings are separated from quadriceps by deep fascia
What are the types of attachments?
- Direct: epimysium fused to periosteum of bone or perichondrium of cartilage
- Indirect: Most attachments are indirect attachments involving either a tendon or an aponeurosis
What are the most common patterns of fascicle arrangement?
Parallel - fascicles parallel to the long axis of a strap like muscle (can be strap like (e.g: sartorius) or fusiform (e.g. biceps brachii))
Pennate - short fascicles attach obliquely to a central tendon running the length of the muscle.
Circular - concentric rings surround external openings & contract to close opening (eg: obicularis oculi)
Convergent - fascicles converge towards a single tendon insertion / muscle is triangular or fan-shaped (eg: pectoralis major)
What are the 3 forms of pennate
unipennate = e.g. extensor digitorum
bipennate = e.g. rectus femoris
multipennate = e.g. deltoid
What is the role of a prime mover(agonist)?
provides major force for a particular movement
e.g.: brachialis in elbow flexion
What is the role of an antagonist?
- opposes or reverses a particular movement
- can provide resistance to prevent overshoot or control rate of movement
What is the role of a synergist?
muscles that help the prime mover by
- promoting the same movement
- reduce undesirable or unnecessary movement (eg: finger flexor muscles cross both wrist & phalangeal joints)
- some are fixators- eg: muscles involved in posture
T or F. a single muscle can be a prime mover for one action & an antagonist for another action
True
What are the characteristics of naming skeletal muscles?
1.Muscle location - bone or body region with which muscle associated e.g., intercostals
2.Muscle shape - e.g., deltoid muscle (deltoid = triangle)
3.Muscle size- e.g. maximus (largest), minimus (smallest), longus (long)
4.Direction of muscle fibers or fascicles -
- rectus (fibers run straight), transversus (fibers run at right angles)
- oblique (fibers run at angles to imaginary defined axis)
5.Number of origins - e.g., biceps (2) or triceps (3) origins
6.Location of attachments - named according to point of origin and insertion (origin named first)
7.Muscle action - named for action they produce, e.g., flexor or extensor
All muscles of the head are innervated by the…
Facial nerve (CN VII)
What is the epicranus
Main muscle of scalp; bipartite muscle
What is the role of the platysma (fascia of chest to mandible):
helps depress mandible; tenses skin of neck (shaving muscle)
What is the role of the orbicularis oculi?
- surround rim of orbit
- protects eyes from light/injury - closes the eye, blinking, squinting, also draws eyebrows inferiorly
What is the role of the orbicularis oris?
lips; multi-layered; closes, purses, protrudes lips
What is the role of the mentalis (mandible to chin)?
V-shaped pair – protrudes lower lip
(pout); wrinkles chin
What is the role of the zygomaticus muscle?
(Zygomatic bone to corner of mouth)
* raises the lateral corners of the mouth (smiling muscle)
What is the role of the buccinator (mandible/maxilla to orbicularis oris)
deep to masseter – whistling, sucking; hold food in place when chewing; especially in nursing infants
The muscles of the tongue are innervated by what…
hypoglossal nerve
The pairs involved in mastication are innervated by the mandiblur division of
cranial nerve V
What is the role of the masseter?
- zygomatic arch & bone to angle & ramus of mandible
- prime mover of jaw closure
What is the role of the temporalis?
o temporal fossa to coronoid process of mandible
elevates and retracts mandible (closes jaw)
maintains closed jaw at rest
What is the role of the medial and lateral pterygoid?
- Pterygoid process of sphenoid to mandible
- additional jaw movements (e.g. side-to-side
grinding movements)
What is the role of the Sternocleidomastoid (manubrium/clavicle to mastoid process of temporal bone)
- 2- headed; deep to the platysma
- prime mover (both muscles) of head flexion (lift
head when lying on back) - muscle action on one side for head rotation to
opposite side, head tilts to same side
What is the role of the scalenes (cervical vertebrae to 1st 2 ribs)
- more laterally and deep to platysma & SCM
- elevates first 2 ribs
- flexes & rotates neck
- aids in inspiration
What is the role of the Splenius (vertebrae to mastoid process of temporal bone)
superficial; “bandage muscle”; head extension (both sides) or if one side, rotation, tilts to same side
What is the role of the erector spinae?
prime mover of back extension; consists of 3 columns of muscles (iliocostalis, longissimus, spinalis); resistance to bending forward & extensors for return to erect position
What is the role of the semispinalis?
deeper, composite muscle from thoracic region to head; extends vertebral column & head, rotation of head, synergistic with sternocleidomastoid muscles
What is the role of the quadratus lumborum (iliac crest to lumbar vertebrae)?
individual muscles flex vertebral column laterally; jointly to extend lumbar spine & fix 12th rib; maintain upright posture
What are the muscles of respiration?
External intercostals, Internal intercostals and Diaphragm
What is the role of the diaphragm?
§ floor of thoracic cavity; dome-shaped when relaxed
§ prime mover of inspiration, flattens on inspiration increasing thoracic volume
Muscles of which part of the boddy support viscera, flexion, stabilize pelvis
Muscles of the Abdominal Wall
What are the names of the fasciae and aponeuroses that form the lateral and anterior abdominal wall
o Internal obliques
o External obliques
o Transversus abdominis
o Rectus abdominis
The Muscles of the Abdominal Wall are innervated by what?
the intercostal nerves
What is the role of the Rectus abdominis (Pubis to rib cage)
- medial, superficial
- Lumbar rotation,
- fix & depress ribs
- stabilizes pelvis during walking
What is the role of the external oblique?
- largest & most superficial lateral muscle
- together they increase abdominal pressure
- flex vertebral column
What is the role of the internal oblique?
deeper but same actions as external oblique
What is the role of the Transversus abdominis
- deepest muscle of abdominal wall
- compresses abdominal contents
What is the role of the Levator ani (pubis to inner coccyx)
- supports visceral organs
- forms the supportive sling at anorectal junction & vagina
- resists downward increases in intra-abdominal pressure (e.g. during coughing, vomiting)
What is the role of the coccyggeus (spine of ischium to sacrum & coccyx)?
It supports pelvic vicera and coccyx
What is the urogenital diaphragm?
It supports pelvic viscera and constricts urethra
The pelvic diaphragm is composed of which two muscles?
levator ani & coccygeus
What is the role of the levator ani (pubis to inner coccyx)?
It supports visceral organs & forms the supportive sling at anorectal junction & vagina; resists downward increases in intra-abdominal pressure (e.g. during coughing, vomiting)
What is the purporse of the muscles of the anterior thorax?
§ join the shoulder girdle to the axial skeleton
§ arm movements
§ fix the scapula
What is the role of the subclavius?
stabilize & depress the pectoral girdle
What is the role of the pectoralis minor?
- draws scapula forward and down
What is the role of the serratus anterior?
holds scapula to chest wall
What are the muscles of the posterior thorax? What is their role
- Trapezius (Occiput & vertebrae to clavicle & scapula) - Superficial; stabilizes, raises, retracts, rotates scapula
- Levator scapulae (C1-4 to scapula) - elevates & adducts the scapula
- Rhomboids (Vertebrae to scapula) - deep to trapezius; aid in scapula movements
What are the prime movers of the arm?
§ Pectoralis major
§ Latissimus dorsi
§ Deltoid
Actions include flexion, extension, adduction, abduction, and rotation of humerus
What are the rotator cuff muscles?
– Supraspinatus
– Infraspinatus
– Teresminor
– Subscapularis
* Reinforce the capsule of the shoulder
* Act as synergists and fixators
True or false, the coracobrachialis and teres major are NOT muscles crossing the shoulder joint.
False. They are
What are the characteristics and roles of the deltoid
o thick, rounded; site of intramuscular injections
o prime mover of arm abduction (all fibers); lateral & medial rotations, flexion or extensions if only some fibers used
What are the characteristics and roles of the pectoralis major?
o prime mover of arm flexion
o adducts & medially rotates arm; climbing, throwing, pushing
What are the characteristics and roles of the latissiumus dorsi?
- broad, flat back muscle
- prime mover of arm extension
- arm adductor, medially rotates arm at shoulder
- rowing, swimming
What are the posterior compartments of the muscles of the forearm?
extensor digitorum
extensor carpi ulnaris
extensor carpi radialis longus/brevis
What are the characteristics and roles of the extensor digitorum?
humerus to phalanges
o prime mover of finger extension
o Extends wrist, can abduct fingers,
o Note separate tendon for each finger and separate muscles
What are the characteristics and roles of the extensor carpi ulnaris?
humerus and ulna to 5th metacarpal
- extends & adducts wrist
What are the characteristics and roles of the extensor carpi radialis longus/brevis?
humerus to 2nd (longus) & 3rd (brevis) metacarpals
- extends & abducts wrist
What are the characteristics and roles of the Extensor pollicis longus and brevis?
radius, ulna & interosseous membrane to proximal (brevis) and distal (longus) phalanx of the thumb
o extends the thumb
What are the characteristics and roles of the supinator?
o assists biceps brachii to supinate forearm
Most anterior muscles flex femur at___, extend leg at ___
hip; knee
Most posterior muscles extend___, flex ___
thigh; leg
What is the role of the biceps brachii
- anterior, flexes elbow joint & supinates forearm
What is the role of the brachialis
- immediately deep to biceps brachii
- major forearm flexor (strong)
- lifts ulna as biceps lifts radius
What is the role of the brachioradialis?
- Superficial / synergist in forearm flexion
What is the role of the triceps brachii?
o only muscle of posterior compartment of arm
o powerful forearm extensor
o may help stabilize shoulder joint
Most anterior muscles are____; insert via ____
flexors; flexor retinaculum
Most posterior muscles are___; insert via ____
extensors; extensor retinaculum
What are the characteristics and roles of the flexor carpi ulnaris?
o powerful flexor of wrist & hand adductor
o synergizes with extensor carpi ulnaris to stabilizes wrist during finger extension
What are the characteristics and roles of the flexor carpi radialis?
- diagonally across forearm
- powerful flexor of wrist
- abducts hand
What are the characteristics and what is the role of the plamaris longus?
- humerus to palmar aponeurosis
- Weak wrist flexor, weak synergist for elbow flexion
What are the characteristics and roles of the pronator teres?
o pronates forearm
o weak flexor of elbow
What are the characteristics and roles of the flexor digitorum?
o 2-headed, deeper
o flexes wrist & middle phalanges of fingers 2-5.
What are the characteristics and roles of the flexor pollicis longus ?
- Anterior shaft of radius & interosseous membrane to distal phalanx of the thumb
- part of the anterior compartment of the forearm
What are the anterior compartments of the muscles of the forearm?
- flexor carpi ulnaris
- flexor retinaculum
- flexor carpi radialis
- flexor digitorum superfixialis
- flexor pollicis longus
- palmaris longus
- pronator teres
the actions of the muscles of the lower limb include :
flexion, extension, abduction, adduction, circumduction, and rotation
Anterior compartements of the leg consists of which prime movers when walking
iliopsoas (two muscles), tensor fascia latae, rectus femoris
Why are abduction and adduction important during walking?
Abduction and adduction are important during walking to place the center of gravity over the grounded limb.
Which medial compartments of the leg participate in the phases of walking?
gluteus medius & minimus
Posterior compartements of the leg consists of which prime movers when walking
gluteus maximus and hamstring (semitendinosus, the semimembranosus, & the biceps femoris)
What are the characteristics and roles of the Iliopsoas?
(iliac crest,T12 & lumbar vertebrae to femur)
*prime mover of hip flexion
What are the names and roles of the quadriceps femoris?
- Rectus femoris - extends the knee ; flexes thigh at hip
- Vastus lateralis
- Vastus medialis
- Vastus intermedius
all extend the knee
What are the characteristics and roles of the sartorius?
(anterior superior iliac spine to medial tibia)
- strap-like; longest muscle;
- flexes & laterally rotates thigh
- weak knee flexor
What are the characteristics and roles of the pectineus?
pubis to femur
- adducts, flexes & medially rotates thigh
What are the characteristics and roles of the gracilis?
pubis and ischial ramus to medial tibia
o adducts thigh, medially rotates leg (walking)
What are the characteristics and roles of the adductors (magnus, longues, brevis)
o all adduct, flex, medially rotate thigh –
e.g. riding a horse, walking, fixing hip when knee flexed
What are the characteristics and roles of the gluteus medius?
(ilium to femur (greater trochanter))
* abducts & medially rotates thigh; esp. during walking (im. injections)
What are the characteristics and roles of the hamstring
- primer movers of thigh extension & knee flexion
- quadriceps antagonists
What are the 3 muscles of the hamstring?
biceps femoris
semitendinousus
semimembranousus
What are the characteristics and roles of the gluteus maximus?
(ilium, sacrum and coccyx to gluteal tuberosity of the femur)
- largest & most superficial buttock muscle
- major thigh extensor - climbing stairs, running
What are the characteristics and roles of the extensor digitorum longus?
tibia to phalanges of toes 2-5
- prime mover of toe extension
- dorsiflexes foot
What are the characteristics and roles of the extensor hallucis longus?
fibula shaft to great toe
* extends great toe & dorsiflexes foot
What are the characteristics and roles of the tibialis anterior?
tibia to tarsals & metatarsal
o prime mover of dorsiflexion
o inverts foot
What are the characteristics and roles of the brevis?
- plantar flexes & everts foot
What are the characteristics and roles of the fibularis (peroneus)
fibula under foot to 1st metatarsal
What are the characteristics and roles of the gastrocnemius?
femur to calcaneus via the calcaneal tendon
- plantar flexes foot when knee extended
- flex knee if foot dorsiflexed
What are the characteristics and roles of the soleus?
- proximal tibia/fibula to calcaneus via calcaneal tendon
- deeper, plantar flexes ankle
- walking, running, dancing
What are the characteristics and roles of the calcaneal (achillens tendon)?
- largest tendon in body
- common tendon for gastrocnemius & soleus muscles for insertion into calcaneus of heel
What are the characteristics and roles of the tibialis posterior?
tibia/fibula/interosseous membrane to tarsal & metarsals
*Primer mover of foot inversion
What are the characteristics and roles of the flexor digitorum longus?
posterior tibia to distal phalanges of toes 2 to5
o Plantar flexes & inverts the foot
o flexes the toes
What are the characteristics and roles of the flexor hallucis longus?
Fibula/interosseous membrane to distal phalanx of great toe
o plantar flexes& inverts the foot, flexes great toe
The Intrinsic muscles of the Foot are similar to which muscles?
Palms of the hands
What actions do Intrinsic muscles of the Foot complete?
Help to flex, extend, abduct and adduct the toes
How do the anterior, medial and posterior compartments of the leg function in the phases of walking?
- Anterior compartment muscles flex the femur and extend the knee - stepping forward.
- Medial compartment adduct the thigh.
- Posterior compartment muscles extend the femur and flex the knee
