The Muscular System
Muscle Organization and Function
Muscular system
•
Includes all skeletal muscle tissue that can be
controlled voluntarily
Organization of skeletal muscle fibers
•
Parallel muscle
•
Convergent muscle
•
Pennate muscle
•
Unipennate
•
Bipennate
•
Multipennate
•
Circular muscle (sphincter)
Levers
•
Rigid structure that moves on a fixed point, the
fulcrum
•
Changes direction and strength of applied force
•
Changes distance and speed of movement
•
Three classes
•
First class
•
Second class
•
Third class
•
Most common in the body
Muscle Terminology
Origins and Insertions
•
Muscles can be identified by origin, insertion and
action
•
Origin = stationary end
•
Insertion = movable end
Actions
•
Muscles can be classified by action
•
Agonist (prime mover)
•
Antagonist
•
Synergist
•
Fixator
Names of skeletal muscles
•
Names give clues to muscle characteristics
•
Location
•
Fascicle organization
•
Relative position
•
Structure
•
Size
•
Shape
•
Origin and insertion
•
Action
Axial and Appendicular Muscles
•
Axial musculature arises on axial skeleton
•
Positions head and spinal column and moves the rib cage
•
Appendicular musculature moves and stabilizes
components of the appendicular skeleton
The Axial Muscles
Axial muscles
•
Logical groupings based on location and/or function
•
Head and neck
•
Vertebral column
•
Oblique and rectus muscles
•
Pelvic floor
Muscles of the head and neck
•
Facial expression muscles
•
Orbicularis oris
•
Buccinator
•
Occipitofrontalis muscles
•
Platysma
Extrinsic eye muscles
(oculomotor or extra-ocular muscles)
•
Inferior and superior rectus muscles
•
Lateral and medial rectus muscles
•
Inferior and superior oblique muscles
Muscles of mastication
•
Masseter muscles
•
Temporalis muscles
•
Pterygoid muscles
Muscles of the tongue
(speech, swallowing and mastication)
•
Genioglossus
•
Hypoglossus
•
Palatoglossus
•
Styloglossus
Muscle of the pharynx
•
Pharyngeal constrictors
•
Laryngeal elevators
•
Palatal muscles
Muscle of the neck
•
Control the position of the larynx
•
Depress the mandible
•
Provide a foundation for the muscles of the tongue
•
Digastric and sternocleidomastoid muscles
•
Seven muscles that originate or insert on the hyoid
Muscles of the vertebral column
•
Superficial muscles of the spine
•
Spinalis
•
Longissimus
•
Iliocostalis
Muscles of the vertebral column
•
Neck region
•
Longus capitus
•
Longus colli
•
Lumbar region
•
Quadratus lumborum
Oblique and rectus muscles
•
Oblique
•
Scalene muscles
•
Intercostal muscles
•
Transverses muscles
•
External and internal intercostals
•
Diaphragm
Muscles of the pelvic floor
•
Perineum
•
Anterior urogenital triangle
•
Posterior anal triangle
•
Pelvic floor
•
Urogenital diaphragm
•
Pelvic diaphragm
The Appendicular Muscles
Muscles of the shoulders and upper arms
•
Trapezius muscles
•
Affect the position of the shoulder girdle, head and
neck
•
Muscles inserting on the scapula
•
Rhomboid muscles
•
Levator scapulae muscles
•
Serratus anterior muscles
•
Subclavius muscles
•
Pectoralis minor muscles
•
Adductors
•
Deltoid muscles
•
Supraspinatus muscles
•
Medial rotators
•
Subscapularis muscles
•
Teres major muscles
•
Lateral rotation
•
Infraspinatus muscles
•
Teres minor muscles
More shoulder movements
•
Flexion and adduction
•
Coracobrachialis
•
Flexion of the shoulder joint
•
Pectoralis major muscles
•
Extension of the shoulder joint
•
Latissimus dorsi
muscles
Muscles that affect the elbow
•
Biceps brachii
muscle
•
Triceps brachii muscle
•
Brachialis and brachioradialis flex the elbow
•
Aconeus muscle extends the elbow
Muscles that affect the wrist
•
Flexion of the wrist
•
Flexor carpi ulnaris
•
Flexor carpi radialis
•
Palmaris longus
•
Extension of the wrist
•
Extensor carpi radialis
•
Extensor carpi ulnaris
Muscles that affect the forearm
•
Pronation of the forearm
•
Pronator teres muscle
•
Pronator quadratus muscle
•
Supination of the forearm
•
Supinator muscle
Muscles of the pelvis and lower limbs
•
Gluteal muscles cover the lateral surfaces of the ilia
•
Gluteus maximus (shares an insertion with the tensor
fasciae latea)
•
Pulls on the iliotibial tract
Lateral rotators of the leg
•
Piriformis muscle
•
Obturator muscles
Adductors perform a variety of functions
Iliopsoas muscle
•
Formed from the merging of the psoas major and the
iliacus muscles
•
Powerful flexor of the hip
Flexors of the knee
•
The hamstrings
•
Biceps femoris muscles
•
Semimembranosus muscles
•
Semitendinosis muscles
•
Popliteus muscle unlocks the knee joint
Extensors of the knee
•
Quadriceps femoris
•
Three vastus muscles
•
Rectus femoris muscle
Movements at the ankle
•
Plantar flexion
•
Gastrocnemius muscle
•
Soleus muscle
•
Eversion and plantar flexion
•
Fibularis muscle
•
Foot position and toe movement is accomplished by
muscles originating on the talus and metatarsal bones
Aging and the Muscular System
With aging
•
Power and size of muscle tissue decrease
•
Skeletal muscles undergo fibrolysis
•
Tolerance for exercise decreases
•
Repair of injuries slows