anatomy chapter 10: gross muscle anatomy

origin or head

muscle end attached to more stationary of two bones

insertion

muscle end attached to bone with greatest movement

tendons

attach muscle to bone

aponeurosis

a very broad tendon

agonist

muscle that, when it contracts, causes an action

antagonist

a muscle working in opposition to agonist

* ex.: the biceps brachii can be used to lift weights and is the agonist, but when you move a bowling ball back to prepare to bowl, the biceps is the antagonist

synergists

muscles that work together to cause a movement

prime mover

plays a major role in accomplishing moement

fixators

stabilize joint/s crossed by the prime mover; prevent movement of the origin of the prime mover

muscles are named according to

* location
* size
* shape
* orientation
* origin and insertion
* number of heads
* function

location

pectoralis, gluteus, brachial

size

maximus, minimus, longus, brevis

shape

deltoid, quadratus, teres

orientation

rectus

origin and insertion

sternocleidomastoid, brachioradialis

number of heads

biceps, triceps

function

abductor, adductor, masseter

massitication

* chewing. involves elevation/depression of the mandible and excursion to grind the teeth together
* acts with muscles of hyoid in movement of the mandible
* muscles of cheek and tongue aid mastication by pushing food under the teeth
* ex.: masseter, temporalis, pterygoids, digastrics

tongue movements

* important in speech: changes shape
* swallowing
* moves food around in mouth
* holds food in place during grinding
* pushes food up to palate and back toward pharynx

thoracic muscles

* involved in breathing

four groups associated iwth rib cage

scalenes, external intercostals, internal intercostals, transversus thoracic, diaphragm

scalenes

elevate first two ribs during inspiration

external intercostals

depress ribs during expiration

transeversus throacis

depresses ribs during expiration

diaphragm

major movement of inspiration. flattens during contraction and increases the volume of the thoracic cavity

abdominal wall

* flex and rotate vertebral column, decrease volume of abdominal and thoracic cavities
* aid in forced expiration, vomiting, defecation, urination, childbirth
* crossing pattern of muscles adds strength to abdominal wall to support organs

rectus abdominus

* linea alba in center
* covered by rectus sheath
* tendinous intersections divided muscle into sections
* flexes vertebral column

external and internal abdominal oblique

flexes and rotates abdomen

transversus abdominis

compress abdominal wall

rotor cuff

* primary muscles holding humerus in the glenoid cavity
* form a cuff or cap over the proximal humerus
* involved in flexion, extension, abduction, adduction, rotation, and circumduction
* infraspinatus, subscapularis supraspinatus, teres minor

intrisic muscles of thehand

originate and insert in hand; fine motor movements

ankle, foot, and toe movements

* extrinsic foot movements
* 3 leg compartments
* anterior compartment
* lateral compartment
* posterior compartment

anterior leg compartment

extensors involved in dorsiflexion and eversion/inversion of foot; extension of toes

* dorsiflex foot; extend toes

lateral leg compartment

plantar flexion and eversion

posterior leg compartment

* superficial muscles (plantar flexion) have common tendon insertion called the calcaneal (Achilles) tendon; gastrocnemius, plantaris


* deep muscles: plantar flex and invert foot

intrisic muscles of the foot

* analogous to intrinsics of hand, but serve in support in locomotion
* flexion, extension, abduction, and adduction of toes
* deep fascia forms plantar aponeurosis