Human Muscular Structure, Diseases, and Actions

Posterior

Posterior

towards the back (Dorsal)

Anterior

towards the front (Ventral)

Medial

towards the middle

Lateral

away from the midline

Superior

towards the head (Cranial)

Inferior

towards the feet (Caudal)

Transverse Plane

a plane that divides human anatomy into superior and inferior portions

Sagittal Plane

a plane that divides human anatomy into medial and lateral portions

Frontal Plane

a plane that divides human anatomy into anterior and posterior portions

Origin of Muscle

where bone and muscle attach, but do NOT move during contraction

Insertion of Muscle

where bone and muscle attach and MOVE during contraction

Function of Skeletal Muscle:

Enables the human body to move and perform all daily tasks

Flexion

Bending bones, bringing them closer together

Extension

Straightening a bone

Adduction

Movement of a limb towards the body

Abduction

Movement of a limb away from the body

Supination

Rotation of the arm so palm paces up

Pronation

Rotation of the arm so the palm faces down

Rotation

Turning a bone around it's own axis

Circumduction

Moving a limb so it's in a cone shape Ex. Arm Circles

Masseter

Origin: Zygomatic Arch Insertion: Ramus of Mandible Action: Elevates mandible

Temporalis

Origin: Temporal Fossa Insertion: Coronoid Process of Mandible Action: Move mandible up, back, and side to side

Digastric

Origin: Anterior = digastric fossa of mandible Posterior = mastoid notch on temporal bone Insertion: Hyoid Bone Action: Depresses mandible and elevates hyoid bone during chewing and swallowing

Sternocleidomastoid

Origin: Manubrium of Sternum and Medial Clavicle Insertion: Mastoid Process Action: Rotation of the head and flexion of the neck

Rectus Abdominus

Origin: Pubic bone Insertion: Xiphoid process and costal cartilage Action: Flexion of trunk

External Oblique

Origin: External surface of ribs 5-12 Insertion: Ilium Action: Flexes and rotates trunk

Pectoralis Major

Origin: Medial part of clavicle, sternum, costal cartilage (ribs 1-6), and rectus sheath Insertion: Crest of greater tubercle of humerus Action: Adductor, and rotates humerus at the shoulder joint

Latissimus Dorsi

Origin: Vertebrae 7-12, Crest of Ilium, Ribs 9-12, Inferior angle of Scapula Insertion: Humerus Action: Arm adduction and extension

Supraspinatus

Part of ROTATOR CUFF Origin: Supraspinous fossa of Scapula Insertion: Greater tubercle of Humerus Action: Abduction of arm

Infraspinatus

Part of ROTATOR CUFF Origin: Infraspinous fossa of Scapula Insertion: Greater tubercle of Humerus Action: External Rotation of arm

Subscapularis

Part of ROTATOR CUFF Origin: Subscapular fossa of Scapula Insertion: Lesser tubercle of Humerus Action: Internal Rotation of arm

Biceps Brachii

FRONT OF ARM Origin: Scapula (coracoid process and supraglenoid tubercle) Insertion: Radial tuberosity of Radius Action: Flexion of elbow

Triceps Brachii

BACK OF ARM Origin: Scapula and Humerus Insertion: Olecranon of Ulna Action: Extension of elbow

Flexor Digitorum Superficialis

Origin: Humerus and radial head Insertion: Sides of phalanges (2-5) Action: Flexion of fingers, hand, and wrist

Trapezius

Origin: Occipital bone, spinous process of vertebrae T1-T12 Insertion: Clavicle, acromion, and spine of scapula Action: Retracts scapula

Gluteus Maximus

Origin: Sacrum, Coccyx, Ilium

Insertion: Femur

Action: Abduction and adduction of thigh

Biceps Femoris

HAMSTRINGS POSTERIOR LATERAL Origin: Ischial tuberosity and femur

Insertion: Head of fibula

Action: Hip and Knee Joint( thigh extension, external rotation, leg flexion and external rotation )

Semitendinosus

HAMSTRINGS POSTERIOR MEDIAL Origin: Ischial Tuberosity Insertion: Tibia (proximal end) Action: Thigh Extension and internal rotation, leg flexion and internal rotation

Rectus Femoris

QUADRISEPS Origin: Iliac spine Insertion: Tibial tuberosity and patella Action: Thigh flexion and leg extension

Vastus Lateralis

QUADRISEPS Origin: Femur Insertion: Tibial tuberosity and patella Action: Leg extension (knee joint)

Gastrocnemius

Origin: Lateral condyle of femur Insertion: Calcaneus Action: Foot flexion and leg flexion (leg joint)

Muscular Dystrophy

Inherited disease (affects males)

• Weakness and wasting away of muscle tissue -9 types (focus on 2)

1. Duchenne Muscular Dystrophy (DMD) Onset: Ages 2-6 Symptoms:

• Weakness in muscles - Eventually involves all muscle

• Survival beyond 20 is rare

2. Becker Muscular Dystrophy Onset: teen-adult Symptoms:

• Same as DMD (just less severe) Survival is into your middle age

Amyotrophic Lateral Sclerosis (ALS)

ALSO CALLED: Lou Gehrigs Disease & Motor Neuron Disease Inherited disease (SLIGHTLY more common in men)

• Motor neuron loss; disease hat affects the nervous system that controls voluntary muscle movement Onset: Middle age- young adult Signs and Symptoms:

• Weak/tight muscles - Muscles eventually become paralyzed (Involuntary muscles and senses aren't affected)

Tetanus

ALSO CALLED: Lockjaw Infectious BACTERIAL disease

• Affects nervous system Causes: (feces, soil, dust, etc.) Spores of bacteria grow and create a chemical called TETANOSPASMIN Signs and Symptoms:

• Spasms/Stiffness in Jaw and Neck - Difficult swallowing

Motor Neuron

controls muscle cells

• apart of the peripheral nervous system

• comes from brain/spinal cord

What is the connection between a muscle fiber and axon of a motor neuron called?

Synapse

How does the nervous system control muscle contraction?

Chemical reactions

Neurotransmitter

A chemical in control of something

Neuromuscular Junction

where a motor neuron connects to muscle fiber

(where muscle fibers are specialized and form a motor end plate)

Acetylcholine

makes muscle fibers contract (stored in DISTAL END OF AXON)

Steps for a bone to move

1. ACh diffuses across synapse

2. ACh binds to muscle fiber membrane (making NA enter the cell)

3. Entry of NA into the muscle cell stimulates a muscle impulse (action potential)

What is calcium?

The key to muscle contraction

(must be in sarcomere)

Calcium in the sarcomere causes…

Actin and Myosin to grab ahold of each other

Muscle Relaxation Steps

1. ACh is destroyed by enzyme acetylcholinesterase

2. No ACh, so calcium is transported back to sarcoplasmic reticulum