Chapter 13: Muscle Anatomy
linea alba
(abdominal muscle) an aponeurosis covering the entire abdominal muscle group providing a protective cover over the abdominal organs, it is the largest aponeurosis in the entire body
transverse abdominus
(abdominal muscle) runs laterally across the abdominal cavity, it helps hold abdominal organs in place, allows the torso to be twisted, and compresses the abdominal cavity
rectus abdominus
(abdominal muscle) the superficial most abdominal muscle, it runs vertically over the abdominal cavity allowing the torso to be pulled forward
external and internal obliques
(abdominal muscles) form an X pattern over the abdomen allowing the torso to be pulled forward and twisted
rotator cuff
(axillary muscle) a group of 6 spiraled muscles that form a partial meniscus within the shoulder joint helping to cushion the humeral head and prevent it from grinding against the scapula, it causes circumduction of the humerus
pectoralis major
(axillary muscle) allows the humerus to be adducted
larissimus dorsi
(axillary muscle) commonly known as the swimmers muscle, it has multiple origins along the lateral surface of the ribcage, it pulls the humerus forward and down
deltoid
(axillary muscle) elevates the humerus and draws it back behind the head
flexor carpi/palmaris longus
(brachial muscle) flex the wrist, 50% of the population have only 2 of those muscles while 50% has 3
extensor digitora
(brachial muscle) insert on the posterior surface of proximal phalanges 2-5 allowing the fingers to be straightened
extensor carpi
(brachial muscle) insert on the posterior surface of the carpals and metacarpals allowing the wrist to be straightened and drawn back
flexor digitora - brachial
(brachial muscle) insert on the proximal phalanges 2-5 drawing the fingers down over the palm of the hand
flexor pollicis
(brachial muscle) inserts on proximal phalanx 1 allowing the thumb to be drawn across the palm of the hand
extensor pollicis
(brachial muscle) inserts on the posterior surface of proximal phalanx 1 allowing the thumb to be straightened
pronator
(brachial muscle) turns the hand into a palm down position
supinator
(brachial muscle) turns the hand into a palm up position
flexor digitora - crural
(crural muscle) allow the 4 true toes to be bent
soleus/plantaris
(crural muscle) allow the foot to be flexed and they support the arch of the foot
flexor hallucis
(crural muscle) bends the big toe
tibialis anterior
(crural muscle) covers the frontal surface of the tibia, the muscle damaged by shin splints, it inserts on the upper surface of the metatarsals allowing flexion of the ankle
peroneus
(crural muscle) everts the foot
popliteus
(crural muscle) inverts the foot
achille's tendon
(crural muscle) it extends the ankle providing the power for a stride or jump
extensor digitora - crural
(crural muscle) straighten the 4 true toes
extensor hallucis
(crural muscle) straightens the big toe
gastrocnemius
(crural muscle) the calf muscle, inserts on the calcaneus via the Achille's tendon
obicularis oris
(facial muscle) a sphincter muscle surrounding the mouth allowing the lips to be puckered
obicularis oculi
(facial muscle) a sphincter muscle that controls opening and closing the eyelid
corrugator
(facial muscle) adducts the eyebrows
buccinator
(facial muscle) compresses the cheeks creating a partial vacuum within the mouth to permit sucking
mentalis
(facial muscle) depresses the lower lip and extends it forward
levator labii
(facial muscle) elevates the upper lip for snarling
nasalis
(facial muscle) flares nostrils
triangularis/platysma/depressor labii
(facial muscle) insert into the corner of the mouth drawing them forward and down for frowning
zygomaticus/risorius
(facial muscle) insert into the corners of the mouth drawing them up and back for smiling
epicranius
(facial muscle) superior most muscle in the body, function is to elevate the eyebrows
hamstrings
(femoral muscle) cover the biceps femoris providing additional force for knee flexion and create 2 additional origin points which help to balance the mass of the leg
quadriceps femoris
(femoral muscle) forms the anterior structure of the thigh, has 4 origins on the femur, it straightens the knee providing the power in a kick
biceps femoris
(femoral muscle) largest muscle on the posterior thigh, it has 2 origins on the femur, it flexes the knee
sartorius
(femoral muscle) longest muscle of the body originating from the femoral head and greater trochanter, it wraps around the femoral shaft and inserts on the posterior tibia, it draws the lower leg up and across the body's midline allowing the legs to be crossed, commonly known as the seamstress muscle/sewers muscle
hypothenar
(hand muscle) deepest muscles within the hand, they insert on the medial phalanges to move the middle digit of each finger
thenar
(hand muscle) insert on the distal phalanges 2-5 allowing movement of the terminal digit of each finger
intermediate
(hand muscle) inserts on distal phalanx 1 to move the terminal digit of the thumb
tensor fasciae
(hip/groin muscle) abduct the femur
gracilis/pectineus/femoral adductors
(hip/groin muscle) commonly known as the groin muscles, they adduct the femur
iliacus/psoas
(hip/groin muscle) elevate the femur
gluteal muscles
(hip/groin muscles) depress the femur and draw it behind the body, they form the structure of the buttocks
biceps brachii/brachialis/brachioradialis
(humeral muscle) flex the elbow
triceps brachii/anconeus
(humeral muscle) straighten/extend the elbow
temporalis/masseter
(mandibular muscle) elevate the mandible for biting and move it laterally for chewing and grinding food
pterygoids
(mandibular muscle) originate from the clavicles and sternum and insert on the chin and body of the mandible, they depress the mandible to open the mouth
digastric muscle
(neck muscle) a non-innervated (having no nerves) muscle positioned between the trachea and the esophagus, it cushions the trachea preventing it from being bent and damaged as food passes through the esophagus
sternocleidomastoid
(neck muscle) largest muscle of the neck, origins are on the sternum and clavicles, it inserts on the mastoid process controlling most of the movements of the head
splenius capitus/longissimus capitus
(neck muscle)positioned on the front of the neck, they pull the head forward
semispinalis capitus
(neck muscles) inserts on the back of the skull, pulling the head back
suprahyoid muscles
(neck muscles) positioned above the hyoid bone, they elevate it to properly position the hyoid and larynx during swallowing
infrahyoid muscles
(neck muscles) positioned below the hyoid bone, they lower it providing tension on the vocal cords during speaking
rhomboideus
(pectoral muscle) depresses and abducts the scapula
subclavis
(pectoral muscle) depresses the clavicle to lower the shoulder
serratus anterior/pectoralis minor
(pectoral muscle) elevate the clavicles to raise the shoulder
levator scapulae
(pectoral muscle) positioned on top of the scapula elevating it when the shoulder is raised
trapezius
(pectoral muscle) positioned on top of the scapulae, it has a triangular architecture which adducts the scapulae
transverse perinei
(pelvic girdle muscle) a non-innervated muscle extending across the pelvic girdle forming a supportive band beneath the intestinal mass preventing the intestines from compressing and damaging the urinary bladder and female reproductive system
sexual dimorphism
(pelvic girdle muscle) any physical trait with a distinct difference between the 2 sexes
levator ani/coccygeus
(pelvic girdle muscle) insert on the rectum elevating and compressing it during defecation
ischiocavernosus
(pelvic girdle muscle) larger in females, it inserts on the uterus, it adds contracting force for labor or menstruation
bulbocavernosus
(pelvic girdle muscle) larger in males, it inserts on the urethra where it aids erection, ejaculation, and urination
hiatus
(respiratory muscle) an opening through the diaphragm allowing the esophagus, spinal cord, and major blood vessels to move from the thoracic cavity into the abdominal cavity and vice versa
internal intercostals
(respiratory muscle) covers the deep, dorsal surface of each rib
external intercostals
(respiratory muscle) covers the superficial, ventral surface of the rib
diaphragm
(respiratory muscle) primary respiratory muscle, it separates the thoracic and abdominal cavities, it's attached to the bottom of the lungs by membranes and pulls on them when it contracts causing them to expand and fill with air
intercostal muscles
(respiratory muscles) they surround and expand the ribs during breathing
abduction
(type of muscle action) movement of a limb away from the bodies midline
adduction
(type of muscle action) movement of a limb towards the bodies midline
eversion
(type of muscle action) pointing the toes away from the body's midline
inversion
(type of muscle action) pointing the toes toward the midline of the body
pronation
(type of muscle action) rotation of the hand into a palm down position
supination
(type of muscle action) rotation of the hand into a palm up position
extension
(type of muscle action) straightening of a hinged joint
flexion
(type of muscle action) the bending of a hinged joint
depression
(type of muscle action) the lowering of a body part
elevation
(type of muscle action) the raising of a body part
circumduction
(type of muscle action) the rotation of a ball and socket joint through a complete 360 degrees around a central axis
longissimus cervicis
(vertebral muscle) extend and retract the head by moving the cervical vertebrae
quadratus lumborum
(vertebral muscle) some of the largest muscles of the body and the most frequently strained muscles of the body, they straighten the lumbar vertebrae
erector spinae/spinalis thoracis
(vertebral muscle) the largest muscle group within the body containing 27 different individual muscles, they move and straighten the thoracic vertebrae
criteria for naming muscles
1. Shape 2. Position In The Body 3. Action 4. Number Of Origins 5. Membership With A Muscle Group
ocular muscles
a group of 6 muscles attached to each eye responsible for its movement within the eye socket
glossal muscles
a group of 8 muscles forming and moving the tongue
spiral muscle
has a twisted spiral shaped gaster with a long thin origin at one end and a single small insertion at the other
sheet muscle
have a broad flat gaster, with all fibers running parallel to each other, the entire gaster is usually covered by a similarly shaped tendon called an aponeurosis functioning as both origin and insertion and helping to support and protect the muscles gaster
sphincter muscle
have a circular gaster with fibers arranged with concentric (bulls-eye pattern) surrounding an opening called an orifice, the diameter of which is controlled by the muscle to regulate the movement of material through the opening
strap muscle
have a thin, long gaster with all fibers running parallel through its fibers are densely packed, making it the strongest type of muscle in the body
triangular muscle
have a triangular shaped gaster with a long thin origin securing it to the bone it does not move. All gaster fibers run in the same direction allowing the bone on which it inserts to be pulled in the direction of the origin.
types of gluteal muscles
i. Maximus ii. Medius iii. Minimus
types of hamstrings
i. Semitendinosus ii. Semimembranosus
femoral muscles
lie on the femur and originate from it and insert on the tibia and fibula
humeral muscles
lie on the humerus and have origins on that bone but are responsible for the movement of the elbow
fusiform muscle
most common type of muscle architecture in the body characterized by a bulb-shaped gaster with large well defined tendons at each end, known as tendon sheaths
crural muscles
muscles of the lower leg, ankle, and foot
pectoral muscles
muscles that insert on the clavicles and scapulae allowing for the movement of those bones
hip/groin muscles
muscles that insert on the femur
axillary muscles
muscles which insert on the humerus resulting in the movement of that bone
brachial muscles
muscles which move the wrists, hands, and fingers
pinnate muscle
normally found in gliding joints, they have a fan shaped gaster with a tendon sheath serving as the origin and multiple small insertions of the different bones of the joint
muscle architecture
refers to the shape of the gaster of a muscle and the shape and number of the origins or insertions
synergistic muscles
those which combine to carry out a single action in the body
antagonistic muscles
those which perform opposite actions in the body