Human Anatomy Lecture Notes - Test 2 PDF

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Human Anatomy Lecture Notes – Test 2 Lecture 8: September 28th Joints 

Also called articulations, and located where two or more bones meet

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Functions: Give skeleton mobility and hold skeleton together

Classification of Joints 

Class: type of tissue holding joints together

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Type: based on function and movement

Class A: Fibrous Joints 

Bones joined by collagen fibers and connective tissue

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Immovable or slightly moveable

Suture Type (Skull bone) 

Has fibers between bones where irregular bone edges interlock giving the joint strength and reduce likelihood of fractures

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Bones are “fused” together; only found in the skull and immovable if you’re 6+ years old o Slightly moveable in younger children/ infants

Syndesmosis 

Ligament outside of the bone is the tissue that connects one bone to another

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Slightly moveable (Ex. Distal tibiofibular joint)

Gomphosis 

Only found in teeth and considered a special type of syndesmosis

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Called a “Peg and socket” type of fibrous joint because periodontal ligaments hold the tooth (peg) in place

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Have very short collagen fibers holding joint in place

Interosseous Membrane 

Have a substantial sheet of connective tissue holding long bones together

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Permits slight movement o Between forearm (radius/ulna) and legs (tibia/fibula)

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Allow attachment points for many muscles

Class B: Cartilaginous 

Bones joined by cartilage

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Immoveable or slightly moveable

Synchondrosis 

Bones joined by hyaline cartilage

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Slightly moveable/immoveable

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Only at first rib where it articulates with manubrium

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Epiphyseal cartilage is a subcategory of synchondrosis o Temporary joint when long bones are growing; disappear when growth is done

Symphysis 

Very solid but allow slight movement (Ex. Child birth)

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Located in the intervertebral disks and pubic symphysis joining two sides of pelvis

Class C: Synovial 

Bones covered with articular cartilage, separated by joint cavity and enclosed within a capsule

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freely moveable (range of motion differs on location)

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Make up most joints in the body

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Articular cartilage: When ends of bones are covered by hyaline cartilage

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Synovial Cavity: contain synovial fluid o Lubricates joints and has nutrients/gasses to move between blood vessels and bones

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Articular capsule: encloses the joint

Plane (Uniaxial) 

Capable of gliding motion (two flat surfaces sliding along with respect to each other)

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Ex. Intertarsal joints, intercarpal joints, superior/inferior articular facets of the spine

Hinge 

Permit uniaxial motions (motion in one plane)

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Ex. Flexion and extension of the knee and elbow, interphalangeal motions of hand/feet Pivot

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Capable of rotation only

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Two bones loosely connected with a ligament holding joint and allowing rotation

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Ex. Proximal radioulnar joint allowing supination/pronation 

Between Atlas and axis (Atlantoaxial joint) allowing head to shake no Condylar 

Allows flexion/extension and Adduction/abduction

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Biaxial since you can move in two axis

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Ex. Metacarpophalangeal joints, wrist joint (where radius and ulna meet carpals)

Saddle 

Allows flexion/extension and adduction/abduction

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Joint surfaces that are curved

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Ex. Between Metacarpal of thumb and trapezium,

Ball and Socket 

Permits flexion/extension, abduction/adduction, internal rotation/external rotation, circumduction

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Full ball with a socket

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Ex. In shoulder and hip

Common Joint injuries Cartilage tear 

Common over use injury usually in synovial joints (Ex. Knee menisci)

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Cartilage fragments can interfere with joint function leading to accelerated wear & tear/arthritis o Typically removed by arthroscopic surgery because cartilage is avascular (cant repair)

Sprains 

Ligaments reinforcing joint are stretched or partially/fully torn o Partial tears are treated through physiotherapy where surrounding muscles are strengthened and range of motion is restored o Full tears require surgery where torn ends are sown back together or grafts are used to connect them

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Healing is slow due to poor vascularization

Strains 

Muscles or tendons are overstretched or torn

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Healing is relatively fast in comparison to cartilage and ligaments

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Partial tears are treated through physiotherapy where surrounding muscles are strengthened and range of motion is restored o Also makes sure muscle is firing properly after healing

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Full tears may or may not require surgery

Inflammatory/degenerative conditions Tendonitis 

Inflammation of tendons form overuse

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Treated with rest, ice, and anti-inflammatory drugs o Slow healing

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Ibuprofen is said to be avoided because it sometimes inhibits bone and soft tissue healing

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Common in tendon of supraspinatus muscle

Arthritis 

Inflammation of the joint and has over 100 types

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Diseases affects joint comfort an function

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Causes include overuse, biomechanical issues, poor alignment, aging, lack of exercise

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Osteoarthritis: bone ends rub together

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Rheumatoid arthritis: swollen and inflamed synovial membrane

Lecture 9: September 30th Muscular System 

Myo/Mys: muscle

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Muscle fiber: a muscle cell (skeletal or smooth) called fibers because they are elongated

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Cardiac muscles aren’t elongated so they’re just called cardiac muscle cells

Muscle tissue 

Converts chemical energy (ATP) to mechanical energy; only type of tissue that does this

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Three types of muscle tissue are:

Smooth muscle 

Set up differently from skeletal muscle, sarcomeres aren’t as organized

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Elongated spindle-shaped fibers (Cells); much smaller than skeletal muscle fibers o Organized diagonally no striations; and one nucleus per cell o Single neuron reaches more muscle fibers vs. skeletal o Some have no nerve supply and contract form chemicals/hormones

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Direction of smooth muscle layers are 90 degrees to each other o Two layers work together alternating between relaxation and contraction to make a wave like motion o Peristalsis: when muscle contraction squeezes material through an organ (Ex. Intestine)

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Located in walls of body organs (except heart) and blood vessels o Also in digestive, urinary, respiratory and reproductive systems

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Controlled by autonomic nervous system (i.e. involuntary)

Cardiac muscle 

Located only in the heart

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Not elongated but have thick and thin filaments striated like skeletal muscle

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Under autonomic nervous system control (involuntary) o Contractions controlled by local electrical systems (like a pacemaker) and the cardiac muscle fibers are autorhythmic 

Repeatedly generate spontaneous action potentials to contract

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Interconnected; allowing it to contract as one (more so than other muscle types) Skeletal muscle 

Attach to bones to move them or resist their movement

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Only type of muscle in our conscious control (Voluntary)

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Longest muscle cells

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Elongated and striated

Components of Skeletal muscle 

Skeletal muscle belly is covered by a layer of epimysium surrounding the whole muscle

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Perimysium surrounds the fascicle

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Endomysium surrounds muscle fiber

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Muscle fiber is made of many myofibrils

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Myofibrils are made of filaments

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Each muscle fiber has a rich blood supply and is supplied with a nerve ending

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Motor unit: a single nerve (neuron) and all of the muscle fibers it supplies

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A motor unit can supply few fibers (fine control in hand) or many fibers (power in legs)

Skeletal Muscle Microscopic Anatomy 

Myofibril: Single contractile fiber in muscle fiber

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Sarcomeres: Repeating units Z-line to Z-line; the contractile unit

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Myofilaments: Thin (actin) and thick (myosin) filaments bind to each other and shorten the sarcomere

o Repeating thick and thin bands pull on each other when there’s muscle contraction and make the muscle look straited (Striped)

Muscle Functions 

Maintain posture and body position

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Stabilizing joints, producing movement and generating heat

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Protecting organs

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Regulating passage of substances

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Constriction/dilation of eyes and blood vessels

Attachments 

Direct: muscle fused to bone or cartilage (Ex. In skull)

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Indirect: tendon/aponeurosis attaches muscle to bone o Periosteum is continuous with tendon which is continuos with epimysium o This is a very strong attachment

Types of Contraction 

Isometric: load is equal to force of contraction; muscle contracts but no movement

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Concentric (Isotonic): force of contraction is stronger than load (muscle shortens)

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Eccentric (Isotonic): load is stronger than force of contraction (muscle lengthens) o Usually against the force of gravity

Force of Muscle contraction Factors affecting force of muscle contraction: 

Number of muscle fibers recruited

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Size of muscle fibers

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Frequency of nerve stimulation

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Degree of muscle stretch o Fibers have an optimal length for maximizing contraction o i.e. if muscle is stretched, thick filament can’t reach thin filament

Origins and insertion 

as it shortens, the insertion moves closer to the origin

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Origin: fixed point of attachment (or more fixed)

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Insertion: attachment on moveable bone

How muscles work 

Muscles can only pull never push

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Instead you have one muscle that does a movement and another that undoes it o Ex. Flexion of the elbow with biceps brachii and extension of the triceps trachii

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Every time a muscle crosses a joint and it’s activated, it will produce an effect on that joint o We coordinate the movement of muscles around a joint to produce a pushing motion, but the muscle is pulling on the bone

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Prime mover: a muscle with the major responsibility of producing a specific movement

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Agonist: secondary muscles which contribute to action of prime mover

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Antagonist: a muscle that opposes a specific movement (usually relaxed/stretched when agonist is active)

Lever systems 

Most skeletal muscles move using leverage

Components of lever system: 

Lever: rigid bar or bone that moves on a fixed point called fulcrum (joint)

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Effort: force (supplied by muscle contraction) applied to lever to move resistance (load)

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Load: resistance (bone + tissues + any added weight) moved by effort

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Effort farther than load from fulcrum= lever operates at a mechanical advantage

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Effort nearer than load to fulcrum= lever operates at a mechanical disadvantage Class

Set up

First class lever

Fulcrum between load and effort Ex. Head extension Load between fulcrum and effort Ex. Plantar flexion Effort between fulcrum and load Ex. Elbow flexion by biceps brachii

Second class lever Third class lever

Naming Muscles 

Location: intercostal (rib); temporalis (temporal bone)

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Shape: teres (round); trapezius (trapezoid)

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Size: Gluteus maximus and minimus

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Direction of muscle fibres: rectus femoris (straight); internal oblique (diagonal)

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Number of origins: biceps brachii (two origins); triceps brachii (three origins)

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Location of attachments: sternocleidomastoid (sternum, clavicle, mastoid process)

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Muscle action: adductor longus

*Contracting a muscle pulls the insertion towards the origin*

Lecture 10: October 5th 2020 Muscular System – Axial Muscles 

Axial muscles attach to the axial skeleton

Neck muscles Sternocleidomastoid 

Origin: clavicle and sternum

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Insertion: mastoid process of temporal bone

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Actions: lateral flexion of head and neck; rotation of head o If only one side is contracted (Ex. Right) your nose and neck will go to opposite direction (left); if both are contracted at the same time you will get neck flexion Trunk muscles Erector spinae 

Made of Spinalis, Longissimus, iliocostalis (on the ribs) o Deeper than other back muscles o Each of these are separated into thoracis (keep posture) and lumborum (prevent bending of spine) regions leading to different actions and tendons

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Posture muscles that control movement of the vertebral column

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Origin: iliac crest, sacrum, lumbar and lower thoracic spinous processes

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Insertion: ribs, transverse/spinous processes of cervical thoracic vertebrae

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Actions: back extension (if both left and right sides contract) and lateral flexion of back (if only one side is contracted)

Quadratus Lumborum 

Origin: iliac crest

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Insertion: inferior border of rib 12, L1-L4

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Actions: lateral flexion of back; if you move your left hand to your knee the left one is activated Thorax muscles

External intercostals *Intercostal means between ribs* 

Most superficial layer; Fibers run down and forward

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Origin: rib above

Insertion: rib below

Action: inspiration

o During inspiration bottom rip is pulled to top rib expanding rib cage (insertion to origin) Internal intercostals

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Fibers run down and backward

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Origin: rib below

Insertion: rib above

Action: expiration

o during expiration top rib is pulled to bottom rib contracting rib cage (insertion to origin) Innermost intercostals 

Deepest layer; Fibers run down and backward

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Origin: rib below

Insertion: rib above

Action: expiration

o during expiration top rib is pulled to bottom rib contracting rib cage (insertion to origin) Diaphragm (P.356) 

major muscle for respiration (more effective than intercostals)

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Origin: lumbar vertebrae, inferior ribs, xiphoid process

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Insertion: central tendon (superior making it look like a dome)

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Action: increases vertical dimensions of thorax for inspiration o Lungs sit on top of diaphragm so when it contracts, lungs are pulled and expand; when it expands lungs are pushed towards the rib cage and contract

Abdominal Muscles 

Antagonist to Erector spinae muscles

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Fibers running in various directions allow protection of organs, movement and resistance

Rectus Abdominis

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Muscle fibers run vertically

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Horizontal tendons divide muscle into 8 sections giving them stability and stopping the muscles from bowing out from the body; fibers would be ripped apart without them o Also allow lateral transmission of force from obliques (deep to the obliques) o All sections contract together

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Linea alba allows left and right sides of the muscles to work together and resists bowing

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Origin: pubis bone

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Insertion: xiphoid process, lower ribs

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Action: trunk flexion, increases intra-abdominal pressure

External oblique 

Run in the direction of front pockets (down and forward like the ribs)

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Superficial to the rectus abdominis (has to be cut to see the rectus abdominis fully)

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Origin: outer surface of ribs

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Insertion: Linea alba, inguinal ligament

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Action: Trunk flexion (contraction of both sides), Trunk lateral rotation (contraction of left oblique, spine will rotate same way), increases intra-abdominal pressure, posture o Lateral flexion: when you contract the left, you bend towards right side o Contraction of this muscle pulls line alba and inguinal ligaments towards ribs

Internal oblique 

Run in the direction of back pockets (down and back)

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Deep to the rectus abdominis and external oblique

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Origin: Lumbar fascia (on back), iliac crest

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Insertion: Linea alba, lower ribs

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Action: Trunk flexion, trunk lateral rotation, increases intra-abdominal pressure, posture o Lateral flexion: when you bend to the left the left one contracts Transversus abdominis 

Deepest abdominal muscles and the fibers run horizontal

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Origin: Lumbar fascia, iliac crest, inguinal ligament

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Insertion: line alba

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Action: increases intra-abdominal pressure, protects organs and provides some posture support

Lecture 11: October 7th Appendicular Muscles – Upper 

Appendicular muscles move and attach to the limb

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*Insertion s pulled toward origin during an action*

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Glenoid fossa points upward w/ upward rotation and downward w/ downward rotation

Shoulder Girdle Trapezius 

Have superior, middle and inferior fibers

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Origin: Nuchal ligament, spines of thoracic vertebrae, occipital bone

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Insertion: clavicle, acromion process, spine of scapula

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Actions: elevation, adduction/retraction, and upward rotation of sc...