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