Download Chapter 10 The Muscular System

Chapter 10 The Muscular System
Skeletal Muscles: Functional Groups
• Prime movers
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Antagonists
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Synergists
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Fixators
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Naming Skeletal Muscles
• Location—
• Shape—
• Relative size—
• Direction of fibers or fascicles—e.g., rectus (fibers run
straight_______________________________ (fibers run at angles to an imaginary defined
axis)
Naming Skeletal Muscles
• ________________________—e.g., biceps (2 origins) and triceps (3 origins)
• _________________________—named according to point of origin or insertion
• ____________________________—e.g., flexor or extensor, muscles that flex or extend,
respectively
Muscle Mechanics: Arrangement of Fascicles
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• Fascicles arranged in concentric rings (e.g., orbicularis oris)
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• Fascicles converge toward a single tendon insertion (e.g., pectoralis major)
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• Fascicles parallel to the long axis of a straplike muscle (e.g., sartorius)
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• Spindle-shaped muscles with parallel fibers (e.g., biceps brachii)
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• Short fascicles attach obliquely to a central tendon running the length of the muscle (e.g.,
rectus femoris)
Major Skeletal Muscles of the Body
• Grouped by function and location
• Information for each muscle
• _____________________________—note information in the name
• _____________________________—there is usually a joint between the origin and the
insertion
• ___________________________—insertion moves toward origin; best learned by acting
out muscle movement on one’s own body
• ___________________________—name of major nerve that supplies the muscle
Muscles of the Head
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Two groups
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Muscles of Facial Expression
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• Important in nonverbal communication
• All innervated by ___________________________________________)
Muscles of Facial Expression
• Epicranius (occipitofrontalis)
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Bipartite muscle consisting of the
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• Galea aponeurotica—
• The two muscles have alternate actions of pulling the scalp forward and backward
Muscles of Mastication and Tongue Movement
• Four pairs involved in mastication
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Prime movers of jaw closure
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Grinding movements
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Muscles of Mastication and Tongue Movement
• All are innervated by ____________________________________________
• _____________________________ (of facial expression group) also help by holding food
between the teeth
• Three muscles anchor and move the tongue
• All are innervated by _______________________________________________
Muscles of the Anterior Neck and Throat
• Most are involved in swallowing
• Two groups
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Suprahyoid Muscles of the Anterior Neck and Throat
• _________________________ are involved in swallowing (they move the hyoid bone and
larynx)
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Form the floor of the oral cavity
Anchor the tongue
Move the hyoid bone and the larynx
Muscles of the Neck and Vertebral Column
• Two functional groups
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Muscles of the Neck and Vertebral Column: Head Movement
• __________________________—major head flexor
• ____________________________________—synergists to head flexion
• ________________________________________—lateral head movements
• ___________________________________—synergist with sternocleidomastoid
• Splenius (capitis and cervicis portions):
Muscles of the Neck and Vertebral Column: Trunk Extension
• Deep (intrinsic) back muscles
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Erector spinae (sacrospinalis) group—prime movers of back extension and lateral bending
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_______________________________________________—synergists in extension and
rotation
Muscles of the Thorax
• Muscles of ______________________________
• _______________________________—more superficial muscles that elevate ribs for
inspiration
• _______________________________—deeper muscles that aid forced expiration
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• Partition between thoracic and abdominal cavities
• Most important muscle in inspiration
• Innervated by phrenic nerves
Muscles of the Abdominal Wall
• Four paired muscles; their fasciae and aponeuroses form the lateral and anterior abdominal
wall
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Muscles of the Abdominal Wall
• Fascicles of these muscles run at angles to one another, _____________________________
• All are innervated by intercostal nerves
• Actions of these muscles
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Help promote ___________________________________________________
Muscles of the Pelvic Floor
• Pelvic floor (pelvic diaphragm) is composed of two paired muscles
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• Both are innervated by _______________________________________________
Muscles of the Pelvic Floor
• Functions of the pelvic diaphragm
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Supports pelvic organs
Resists increased intra-abdominal pressure
Muscles of the Perineum
• Urogenital diaphragm
• Anterior half of perineum, inferior to pelvic floor
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External urethral sphincter (voluntary control of urination)
Superficial Muscles of the Thorax
• Most are extrinsic shoulder muscles
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Act in combination to _____________________________ (mostly the scapula) and move it
to increase range of arm movements
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Actions include
_________________________________________________________________
Superficial Muscles of the Thorax
• Anterior extrinsic shoulder muscles
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• (Pectoralis major considered later with muscles that act on the humerus)
Superficial Muscles of the Posterior Thorax
• Posterior extrinsic shoulder muscles
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____________________________________________ (major and minor)
• (Latissimus dorsi considered later with muscles that act on the humerus)
Muscles Crossing the Shoulder Joint
• Nine muscles cross the shoulder joint to insert on and move the humerus
• Three are prime movers of the arm
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• Actions include _______________________________________________ of humerus
Muscles Crossing the Shoulder Joint
• Four muscles are rotator cuff muscles
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___________________________________ the capsule of the shoulder
Act as synergists and fixators
Two additional muscles are synergists:
Muscles Crossing the Elbow Joint
• Anterior flexor muscles
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Brachialis and biceps brachii—
Brachioradialis—
Muscles Crossing the Elbow Joint
• Posterior extensor muscles
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Triceps brachii—
Anconeus—
Muscles of the Forearm
• Actions:
• Most anterior muscles are flexors and insert via the ______________________________
• Most posterior muscles are extensors and insert via the _______________________________
• Some forearm muscles act to produce ____________________________ of the forearm
Muscles of the Forearm
• Pronators: pronator teres and pronator quadratus
• Supinator: a synergist with the biceps brachii
• Flexors
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Muscles of the Forearm: Posterior Compartment
• Extensors
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Intrinsic Muscles of the Hand
• Small weak muscles
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Lie entirely within the palm of the hand
Control ____________________________ of metacarpals and fingers (e.g., threading a
needle)
Abductors and adductors of the fingers
Produce opposition—
Finger and Thumb Movements
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Thumb—bends medially along the palm
Fingers—bend anteriorly
Thumb—points laterally
Fingers—move posteriorly
Intrinsic Muscles of the Hand
• Three groups
• __________________________________ (ball of the thumb)
• _____________________________________ (ball of the little finger)
• Each of the above groups has a flexor, an abductor, and an opponens muscle
• Midpalmar muscles: lumbricals and palmar and dorsal interossei extend the fingers
• Interossei muscles also abduct and adduct the fingers
Muscles Crossing Hip and Knee Joints
• Most anterior muscles _____________________ the femur at the hip and
___________________ the leg at the knee (foreswing of walking)
• Most posterior muscles _________________ the thigh and _________________ the leg
(backswing of walking)
• Medial muscles all _______________________ the thigh
• All three groups are enclosed by the ________________________________
Movements of the Thigh
• Include flexion, extension, abduction, adduction, circumduction, and rotation
• Thigh flexors pass in front of the hip joint
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Iliopsoas (iliacus and psoas major):
• Assisted by medial adductors and sartorius
Movements of the Thigh
• Thigh extensors
• Hamstring muscles (prime movers of extension)
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___________________________________ (prime mover during forceful extension)
Movements of the Thigh
• Adductors (also medially rotate thigh)
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Movements of the Thigh
• Abductors
• _________________________ (also laterally rotates thigh)
• _____________________________ (also medially rotates thigh)
• ___________________________ (also medially rotates thigh)
• __________________________ (also laterally rotates thigh)
• _____________________________ (also laterally rotates thigh)
• _____________________________ (also laterally rotates thigh)
• ____________________________ (also laterally rotates thigh)
Muscles of the Thigh that Move the Knee Joint
• Quadriceps femoris—
• Hamstring muscles—
Fascia of the Leg
• A deep fascia of the leg is continuous with the fascia lata
• This fascia segregates the leg into three compartments: anterior, lateral, and posterior
• Distally, the fascia thickens and forms the flexor, extensor, and fibular retinaculae
Muscles of the Leg: Movements
• Various leg muscles produce the following movements
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Ankle—
Intertarsal joints—
Toes—
Muscles of the Anterior Compartment of
the Leg
• Primary toe extensors and ankle dorsiflexors
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Muscles of the Lateral Compartment of
the Leg
• Plantar flexion and eversion of the foot
• Fibularis longus
• Fibularis brevis
Muscles of the Posterior Compartment of the Leg
• Flexors of the foot and the toes
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Intrinsic Muscles of the Foot
• Help __________________________________________
• Support the arches of the foot along with some leg tendons
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Extensor digitorum brevis—
Plantar Muscles
• The plantar muscles occur in four layers
• Superficial layer
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Second layer
• Flexor accessorius
• Lumbricals
Plantar Muscles
3. Third layer
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Flexor hallucis brevis
Adductor hallucis
Flexor digiti minimi brevis
4. Deepest layer
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Plantar and dorsal interossei