Human Muscles

Types of Muscle Cells  Skeletal (Voluntary, Striated) Muscle  these are muscles you control; the ones you exercise.  Smooth (Involuntary, Smooth) Muscle  these are muscles you cannot control  They work the inner parts of the body (viscera)  Cardiac Muscle (Involuntary, striated)  myogenic due to interconnections  These muscles of the heart do not get tired.

Types of Muscle Cells

Smooth Muscle Cells

Cardiac Muscle Cells

Skeletal Muscle Cells

Tissues in Skeletal Muscles 1. Skeletal muscle tissue 2. Connective Tissue Components 3. Nervous Tissue

Connective Tissue Components  Endomysium  Perimysium  Fascicles  Epimysium  Tendon

Tendon Pictures

Aponeurosis  Also may be formed from the three fibrous wrappings  may merge with the wrappings of another muscle.

Size and Shape of Fibers  Size: varies from large to small  Shape: varies  Broad: Latisimus dorsi  Narrow: Sartorius  Flat: Latisimus dorsi  Bulky: Gastrocnemius  Long: Sartorius  Circular: Orbicularis oris  Triangular: Deltoid

Shape: Broad  Latisimus dorsi

Shape: Narrow  Sartorius

Shape: Flat  Latisimus dorsi

Shape: Bulky  Gastrocnemius

Shape: Long  Sartorius

Shape: Circular  Orbicularis oris

Shape: Triangular  Deltoid

Fiber Arrangement Arrangement of SMF within the muscle, varies.  Parallel to long axis  Converge to narrow attachment  Oblique are slanted  Pennate – “think feather pen”  Bipennate  Curved

Parallel to long axis  Horizontal: Transversus abdominis

Vertical  Rectus abdominis

Converge to narrow attachment  Pectoralis major

Oblique are slanted  External oblique

Pennate – “think feather pen”  Vastus group

Bipennate  “two feathered”  Rectus femoris

Curved  Fibers are circular  Orbicularus oris

Attachment of Muscles-Joints  Most muscles attach articulating bones across a joint.  Upon contraction of the muscle, one bone remains in a fixed position and the other moves. Femur Pelvis

Attachment of Muscles- Origin  Origin  The point of attachment  that does not move during muscle contraction. Pelvis

Attachment of Muscles- Insertion  Insertion – the point of attachment that does move when the muscles contract. Femur

Attachment of Muscles-Contraction  Typically, when a muscle contracts, the insertion is moved closer to the origin.

ROLE OF MUSCLES, BONES, AND JOINTS IN MOVEMENT  Lever  any rigid bar free to move around a fixed point called a fulcrum  Lever system  Rigid bar - a bone  F = Fulcrum - joint  a point around which the rigid bar rotates  L = Load: Weight – resistance  something that is moved  P = Pull - Muscle contraction  force producing the movement

Muscle Groups  Muscles work together! Some muscles in a group contract while other relax.  Prime mover  Antagonist  Synergists  Fixator muscles

Prime Mover  A muscle or group of muscles which directly performs a specific movement.  Flexion of forearm  Biceps brachii is PM

Antagonist  When actively contracting,  they oppose the movement of the prime mover.  They are relaxed when the prime mover is contracting.  Flexion of forearm  T. brachii is anatagonist

Synergists  contract at the same time as the prime movers;  they complement the prime movers.  Flexion of forearm  brachialis is synergist

Fixator muscles  usually serve to stabilize joints. They help to maintain balance and posture during the contractions of the prime movers.

Naming of Muscles  Location  Function - named for what they do  Shape - shape of the muscle  Direction of fibers - orientation of fibers  Number of divisions or heads - connections  Points of attachment - what bones are attached to OR bone markings  Size - how big is the muscle relative to other muscles

Location brachialis - in the arm

Function - named for what they do  Adductor group  move leg toward the midline

Shape - shape of the muscle  deltoid - triangular muscle in the shoulder

Direction of fibers - orientation of fibers  rectus abdominus  rectus refers to up and down  Oblique  slanting  transversus

Number of divisions or heads – connections  biceps brachii

Points of attachment  What bones are attached to OR bone markings  Sternocleidomastoid

Size  how big is the muscle relative to other muscles  Gluteus maximus – in human beings, bigger than gluteus medius and minimus.