Chapter 10, Marieb Human A and P text, 8th Ed.
Muscles pull on bones and act as lever systems. Muscles have an tendinous
is immovable, and a tendinous insertion which is movable.
Classes of Levers (review) - see p. 325.
First Class Lever - resembles a see-saw with a fulcrum in the
middle of the force
and effort. It is diagrammed as E-F-R. An example is the splenius capitis which inserts
on the occipital bone of the skull, extending it (the force) and pulling the chin
(the resistance). Examine the illustration on p. 325, which joint is the fulcrum?
Second Class Lever - resembles a wheel barrow - the gastrocnemius
the heel (calcaneus) upward [like you are lifting the handles of the wheel barrow], this
causes the metatarsal/phalange [the wheel] joint to press against the floor. When you
stand up on your toes, the resistance is the weight of the body pressing down on the
ankles. The second class lever is diagrammed F-R-E.
Third Class Lever - the fulcrum and resistance are at opposite
ends, the effort in
between. The historical Jesus picked up and shouldered his cross this way. Examples
are the adductors of the thigh, tweezers, and lifting a shovel of dirt. The fulcrum is
the hip joint, the effort is the adductors' contractions and the resistance is the weight
of the leg. The third class lever is diagrammed F-E-R.
For instance, your biceps will flex your forearm by pulling on its insertion
radius. The biceps of the anterior muscle compartment is the primary mover or
agonist. Opposing the action of the biceps is the triceps of the posterior muscle
compartment of the arm - the triceps is the antagonist of the movement. If you
extend your forearm, the actions and functions of the two muscles are reversed.
In order to flex or extend a forearm carrying a heavy load, the shoulder
must be held in place. The rhomboideus muscles would serve as fixators.
Many movements also require that muscles serve as synergists which assist the movement.
SELECTED MUSCLES AND FUNCTIONS
Most of the muscles and their movements will be covered in lab.
|Occipitalis||Occipital/galea aponeurosis||draws scalp backwards|
|Frontalis||Frontal/galea aponeurosis||draws scalp forwards, wrinles forehead|
|Orbicularis oris||skin at corners of mouth||closes lips|
|Zygomaticus||zygomatic process/mouth corner||smiling|
|Depressor anguli oris||mandible/mouth corner||frowning|
|Risorius||parotid fascia/corner of mouth||“rage” expression|
|Orbicularis oculi||orbit/orbit||closes eyes|
|Temporalis||parietal/coranoid process of mandible||chewing|
Label as above. See p. 330.
|Digastric||mandible + mastoid/hyoid||opens mouth|
|Mylohyoid||inner mandible/hyoid||aids swallowing, flattens floor of mouth and elevates the tongue|
Label as above. See p. 341
|Sternocleidomastoid||sternum + clavicle/mastoid||turns head R or L, shrug shoulders|
|Splenius capitis||vertebrae/occipital||extends head|
Label as above. See p. 333.
|Rectus abdominus||pubis/rib cartilages||tightens mid-line in defecation|
|External oblique||ribs/linea alba||compresses abdomen|
|Internal oblique||iliac crest/rib cartilages||compresses abdomen|
|Transverse abdominus||iliac crest/linea alba||compresses abdomen|
|Thoracic - deep|
|Diaphragm||ribs + lumbar vert./central tendon||inhalation, increases volume of the thoracic cavity|
|External intercostals||adjacent ribs||elevates rib cage in inhalation|
|Internal intercostals||adjacent ribs||depresses rib cage|
|Pectoralis minor||ribs #3-5 /coracoid of scapula||moves scapula anteriorly, elevates rib cage|
|Thoracic - superficial|
|Pectoralis major||sternum and clavicle/greater tubercle of humerus||adducts arm|
Label as above. See p. 343.
|Serratus anterior||ribs/scapula||abducts scapula, elevates ribs.
What is winged scapula?
Label as above. See pg. 352.
|Trapezius||occipital + vertebrae/clavicle + scapula||upper div. elevates clavicle; for climbing, elevates scapula|
|Levator scapulae||cervical vertebrae/scapula||elevates scapula|
|Rhomboideus||thoracic vertebrae/scapula||adducts and fixates scapula|
|Latissimus dorsi||vertebrae/humerus||draws arm back|
|Quadratus lumborum||iliac crest/12th rib and lumbar vertebrae||draws torso R and L inferiorly|
(Use the cat terms for the three sections of the trapezius. See
the Mareib lab manual.)
Label as above. See p. 354-357
SHOULDER/ARM - See p. 351.
|Teres major||scapula/intertubular groove of humerus||adducts arm|
|Teres minor||inf. border scapula/great.tub.of humerus||rotates arm laterally|
|Deltoid||clavicle + scapular spine/deltoid
tuberosity of humerus
|flexes and abducts arm|
Use the cat terms (achromiodeltod, clavodeltoid and spinodeltoid) for the three sections of the deltoid.
|Subscapularis||anterior scapula/humerus||rotates arm medially|
Name this muscle.
|Supraspinatus||posterior, upper scapula/tubercle
|Infraspinatus||inf. angle of scapula/tubercle of humerus||rotates arm laterally|
ARM - See p. 352-354.
|Biceps brachii||coracoid + scapula/radius||flexes forearm, flexes arm|
|Brachialis||ant. humerus/ulna||flexes forearm|
|Brachioradialis||distal humerus/radius||flexes forearm|
|Triceps brachii||post.scapula, glenoid fossa and humerus/olecranon process||extends forearm|
|Pronator teres||med. epicondyle of humerus/radius||pronates arm|
|Supinator||lat. epicondyle of humerus/radius||supinates arm and hand|
Label as above. See p. 352.
Label as above. See p. 352.
HIP and THIGH - See p. 364.
|Iliacus||ant.iliac fossa/lesser trochanter
via psoas tendon
|flexes and rotates thigh laterally|
|Psoas major||lumbar vert./lesser trochanter||as above|
|Pectineus||pubis/femur||flexes, adducts thigh|
|Gluteus maximus||post. sacroiliac area/post. femur under greater trochanter||rotates thigh laterally|
|Gluteus medius||Iiium/greater trochanter||rotates thigh medially|
|Tensor fasciae latae||Iiiac crest/ant.tibia||flexes, abducts thigh|
|Adductor longus/magnus||pubis/linea aspera of femur||adducts thigh|
Label as above. See p. 364.
|Rectus femoris||iliac spine/patella||flexes thigh and extends leg|
|Vastus lateralis, medialis, intermedius||greater trocanter and linea aspera/tibial tuberosity via the patellar tendon||extends leg|
Label as above. See p. 364.
|Biceps femoris||ischial tuberosity + linea aspera/fibula and lat. condyle of tibia||extends thigh and flexes leg|
|Semitendinosus||ischial tuberosity/tibia||flexes leg|
|Semimembranosus||ischial tuberosity/med.condyle of tibia||as above|
Label as above. See pg. 367.
|Sartorius||iliac spine/tibia||rotates leg laterally|
|Tibialis anterior||tibia/ superior first metatarsal||dorsiflexes foot|
|Extensor digitorum longus||tibia + fibula/phalanges||extends toes|
|Peroneus longus||fibula + tibia/inferior first metatarsal||everts foot, plantar flexes foot|
Shinsplints is a term for inflammations of the tibial periosteum
of tendinitis associated with the
tibialis posterior or anterior. It usually results from running on hard surfaces.
Label as above. See p. 371.
|Gastrocnemius||post.knee/calcaneus||plantar flexion, "standing on toes,” flexes leg|
|Flexor digitorum longus||post.tibia/distal phalanges||flexes toes, inverts foot|
1. What is RICE therapy for muscle injuries?
2. Which muscles are the typical ones for arm, hip and thigh injections?
3. Compare the lever classes and explain one example of each.
4. Review the principal actions of the muscles above by making your own table.