Human Muscular Structure, Diseases, and Actions

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