Parallel Muscles Figure 11–1a

Skeletal Motion  Skeletal muscles attach to skeleton, produce motion  Type of muscle attachment affects power, range, and speed of muscle movement

Levers  Mechanically, each bone is a lever (a rigid, moving structure):  and each joint a fulcrum (a fixed point)  Muscles provide applied force (AF):  required to overcome resistance (R)

Functions of a Lever  To change:  direction of an AF  distance and speed of movement produced by an AF  effective strength of an AF

First-Class Levers Figure 11–2a

First-Class Levers  Seesaw is an example  Center fulcrum between applied force and resistance  Force and resistance are balanced

Second–Class Levers Figure 11–2b

Second-Class Levers  Wheelbarrow is an example  Center resistance between applied force and fulcrum  A small force moves a large weight

Third-Class Levers Figure 11–2c

Third-Class Levers  Most common levers in the body  Center applied force between resistance and fulcrum  Greater force moves smaller resistance  Maximizes speed and distance traveled

KEY CONCEPT  Skeletal muscles can shorten to 70% of resting length  Power, speed, and range of movement  Depend on positions of muscle attachment  Relative to joints

Origins and Insertions  Muscles have 1 fixed point of attachment (origin) and 1 moving point of attachment (insertion)  Most muscles originate or insert on the skeleton  Origin is usually proximal to insertion

Muscle Terminology Based on Function  Agonist (prime mover):  produces a particular movement  Antagonist:  opposes movement of a particular agonist

Muscle Terminology Based on Function  Synergist:  a smaller muscle that assists a larger agonist  helps start motion or stabilize origin of agonist (fixator)

Muscle Opposition  Agonists and antagonists work in pairs:  when 1 contracts, the other stretches  i.e., flexors–extensors, abductors– adductors, etc.

Location in the Body  Identifies body regions:  e.g., temporalis muscle

Origin and Insertion  First part of name indicates origin  Second part of name indicates insertion:  e.g., genioglossus muscle

Fascicle Organization  Describes fascicle orientation within muscle:  i.e., rectus (straight), transversus, oblique

Relative Position  Externus (superficialis):  visible at body surface  Internus (profundus):  deep muscles  Extrinsic:  muscles outside an organ  Intrinsic:  muscles inside an organ

Structural Characteristics  Number of tendons:  bi = 2, tri = 3  Shape:  trapezius, deltoid, rhomboid  Size

Names for Muscle Size (1 of 2)  Longus = long  Longissimus = longest  Teres = long and round  Brevis = short  Magnus = large

Names For Muscle Size (2 of 2)  Major = larger  Maximus = largest  Minor = small  Minimus = smallest

Action  Movements:  e.g., flexor, extensor, retractor  Occupations or habits:  e.g., risor = laughter

Divisions of the Muscular System 1.Axial muscles:  position head and spinal column  move rib cage  60% of skeletal muscles 2.Appendicular muscles:  support pectoral and pelvic girdles  support limbs  40% of skeletal muscles

The Axial Muscles  Divisions based on location and function:  muscles of head and neck  muscles of vertebral column  oblique and rectus muscles  muscles of pelvic floor

Muscles of Facial Expression Figure 11–4b

Muscles of Facial Expression  Orbicularis oris:  constricts the mouth opening  Buccinator:  moves food around the cheeks  Muscles of the epicranium (scalp)

Muscles of the Epicranium (Scalp)  Temporoparietalis  Occipitofrontalis:  frontal and occipital bellies  separated by epicranial aponeurosis  Platysma:  covers anterior surface of neck

Extrinsic Eye Muscles  Also called extra-ocular muscles Figure 11–5a, b

Extrinsic Eye Muscles Figure 11–5c

Muscles of Mastication Figure 11–6

3 Muscles of Mastication  Masseter:  the strongest jaw muscle  Temporalis:  helps lift the mandible  Pterygoid muscles:  position mandible for chewing

Muscles of the Tongue Figure 11–7

4 Muscles of the Tongue  Palatoglossus:  originates at palate  Styloglossus:  originates at styloid process  Genioglossus:  originates at chin  Hypoglossus:  originates at hyoid bone

Muscles of the Pharynx Figure 11–8

3 Muscles of the Pharynx  Pharyngeal constrictor muscles:  move food into esophagus  Laryngeal elevator muscles:  elevate the larynx  Palatal muscles:  lift the soft palate

Anterior Muscles of the Neck Figure 11–9

6 Anterior Muscles of the Neck  Digastric:  from chin to hyoid  and hyoid to mastoid  Mylohyoid:  floor of the mouth  Geniohyoid:  between hyoid and chin

6 Anterior Muscles of the Neck  Stylohyoid:  between hyloid and styloid  Sternocleidomastoid:  from clavicle and sternum to mastoid  Omohyoid:  attaches scapula, clavicle, first rib, and hyoid

Muscles of the Vertebral Column Figure 11–10a

Muscles of the Vertebral Column Figure 11–10b, c

Oblique and Rectus Muscles  Lie within the body wall Figure 11–11a, b

Oblique and Rectus Muscles Figure 11–11a, c

Muscles of the Pelvic Floor Figure 11–12a

Muscles of the Pelvic Floor Figure 11–12b

The Appendicular Muscles Figure 11–13a

The Appendicular Muscles Figure 11–13b

3D Peel-Away of Muscles of the Pectoral Girdle PLAY Muscles that Position the Pectoral Girdle Figure 11–14a

Muscles that Position the Pectoral Girdle Figure 11–14b

Muscles that Move the Arm Figure 11–15a

Muscles that Move the Arm Figure 11–15b

Muscles that Move the Forearm and Hand Figure 11–16a

Muscles that Move the Forearm and Hand Figure 11–16b

Muscles that Move the Hand and Fingers Figure 11–17a, b

Muscles that Move the Hand and Fingers Figure 11–17c, d

The Intrinsic Muscles of the Hand Figure 11–18a

The Intrinsic Muscles of the Hand Figure 11–18b

Muscles that Move the Thigh Figure 11–19a, b

Muscles that Move the Thigh Figure 11–19c, d

Muscles that Move the Leg Figure 11–20a

Muscles that Move the Leg Figure 11–20b, c

Muscles that Move the Foot and Toes Figure 11–21a, b

Muscles that Move the Foot and Toes Figure 11–21c, d

The Intrinsic Muscles of the Foot Figure 11–22a

The Intrinsic Muscles of the Foot Figure 11–22b, c

Summary: The Intrinsic Muscles of the Foot Table 11–19

Integration with Other Systems (1 of 2)  Cardiovascular system:  delivers oxygen and fuel  removes carbon dioxide and wastes  Respiratory system:  responds to oxygen demand of muscles