7/29/2019 Lecture 4 - Basic Anatomy and Biomechanics

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BASIC ANATOMY &

BIOMECHANICS

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About Muscle

Connect to bones via tendons

Each muscle is made of many fibers

There are different types of fibers Type I slow twitch (lower force)

Type II fast twitch (higher force)

Type IIa intermediate

Type I fibers activated first

Type II fibers activated only as needed

Everyone and each muscle group has a differentproportion of each fiber type

Fiber types dont really change (type IIa can go eitherway)

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Upper Body Muscles

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Lower Body Muscles

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Basic Biomechanics

Muscles ONLY pull, not push

Each movement has 1-3 prime movers Bench press: pectorals, triceps

Every movement also has secondary or stabilizing musculature

Squat: the core musculature stabilizes the trunk and torso Torque is greater when the load is farther away from the

muscle group generating force

Changing grip width, foot placement, joint/body angle, etc., canchange how the exercise works the muscle

Moving against the pull of gravity is harder than movingperpendicular to it (or at an angle). Squat vs. leg press

Not all weight machines are created equal Different pulley systems create different amounts of resistance

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Muscle Actions Upper body Pectoralis major

Pulls the arm forward and across the body; rotates the upper arm inwardly.

Serratus anterior

Moves the scapula laterally, and rolls its inferior angle upward to raise the arm above the shoulder.

Latissimus dorsi

Extends the shoulder - pulls upper arm downward towards the torso and behind the back.

Deltoid Raises the arm at the shoulder.

Rhomboids

Draws the scapula toward the spine, and rotates its inferior angle medially.

Trapezius

The upper third raises the scapula; with the scapula fixed, it draws the head upright, backward, toward

the shoulder, and rotates the face to the opposite side. The middle third draws the scapula towards thespine; the lower third draws it downward. Both sides together extend the head.

Biceps

Bends the arm at the elbow and turns the forearm palm-up

Triceps

Extends arm at elbow.

Rectus abdominis Bends ribcage forward toward hips, and vice-versa.

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Muscle Actions Lower Body

Gluteus maximus Straightens the thigh at the hip and draws it backwards.

Gluteus medius Lifts the thigh to the side. Its anterior and posterior portions rotate it

medially and laterally respectively.

Vastus medialis, intermedius, and lateralis Straightens the leg at the knee.

Rectus femoris Straightens the leg at the knee, and bends it at the hip.

Hamstrings (semitendinosus, semimembranosus, bicepsfemoris) Pulls the thigh backwards and bends the leg at the knee.

Gastrocnemius and soleus Straightens the ankle joint

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Exercise Variation

Regular curls

Emphasize the Biceps Brachii

Reverse curls

Emphasize the Brachialis

Hammer Curls

Emphasize the Brachioradialis

Regular (forward) curls Reverse curls Hammer curls

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Exercise Variation

Flat bench press

Uses both heads of the Pectoralis Major

Incline bench press

Emphasizes the clavicular head

Decline bench press

Emphasizes the sternal head

Sternal Head

Clavicular Head

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The Spine

Consists of:

7 Cervical (neck)

12 Thoracic (ribs)

5 Lumbar (low back) 5 sacral and 4 Coccygeal

Intervertebral discs

85% of adults will

experience back pain atsome point in their life!

Always maintain a neutral

spine when lifting!

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The Shoulder Rotator cuff (SITS) maintains

humeral head in glenoid cavity

Scapula glides along the

ribcage

Poor t-spine mobility/position can

cause scapular movementdysfunction

If you press a lot, you need to

pull a lot!

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Question: Why the big concern over upper back mobility in regard to building healthy shoulders?

Answer: Poor mobility of the thoracic spine (upper back) is often associated with a slouched, or more

specifically, a kyphotic posture. This altered spinal alignment prevents the scapulae (the shoulder

blades) from tilting backward as you raise your arms. This lack of tilt narrows the space in the shoulder

joint that the rotator cuff runs through (the subacromial space) and makes it more likely that your rotator

cuff will get pinched, called impingement. Over time, if you impinge frequently, youll most likely end up

with some form of rotator cuff injury.

The mobility of the thoracic spine also directly affects the strength of the lower trapezius which is an

upward rotator of the scapulae. If the thoracic spine lacks mobility the lower trapezius will test weak,

thus limiting upward rotation. A lack of scapular upward rotation also narrows the subacromial space

making impingement more likely.

http://www.billhartman.net/blog/the-thoracic-spine-and-shoulder-health/

http://www.billhartman.net/blog/the-thoracic-spine-and-shoulder-health/http://www.billhartman.net/blog/the-thoracic-spine-and-shoulder-health/http://www.billhartman.net/blog/the-thoracic-spine-and-shoulder-health/http://www.billhartman.net/blog/the-thoracic-spine-and-shoulder-health/http://www.billhartman.net/blog/the-thoracic-spine-and-shoulder-health/http://www.billhartman.net/blog/the-thoracic-spine-and-shoulder-health/http://www.billhartman.net/blog/the-thoracic-spine-and-shoulder-health/http://www.billhartman.net/blog/the-thoracic-spine-and-shoulder-health/http://www.billhartman.net/blog/the-thoracic-spine-and-shoulder-health/http://www.billhartman.net/blog/the-thoracic-spine-and-shoulder-health/http://www.billhartman.net/blog/the-thoracic-spine-and-shoulder-health/http://www.billhartman.net/blog/the-thoracic-spine-and-shoulder-health/

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The Knee

Increased Q angle andValgus stress Can led to knee pain, ACL tears,

ITB syndrome

Strengthen the outer hip

muscles! Hamstrings cross knee and

hip joint Extends hip and flexes knee

Provides posterior pull on tibia

with knee flexion Squatting deep allows for

greater activation of thehamstrings Helps prevent knee pain

http://bretcontreras.com/knee-valgus-valgus-collapse-glute-medius-strengthening-band-hip-abduction-exercises-and-ankle-dorsiflexion-drills/

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Questions?