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Human Anatomy

Sport Books Publisher 1

Chapter 2

Table of ContentsIntroduction

Terms and Concepts Worth Knowing– Anatomical Position


– Directional Terms– Planes of the Body

The Musculoskeletal System– Bones– Joints– Muscles

Introduction: What is the Structure of My Body?

Human Anatomy: The study of the structures that make up the human body and how those structures

l t t h th


relate to each other.

Structure determines function: The structures of the human body are well-designed for efficient movement.

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Terms and Concepts Worth Knowing


Anatomical Position


– Legs straight– Heels feet and great toes

– Palms facing forward and the thumbs outward

Description– Standing erect– Facing forward– Arms hanging at the sides


Heels, feet and great toes parallel to each other

The starting reference point for describing the human bodyIt is universally accepted It is used in all anatomical descriptions

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Directional Terms


Reminder:

All directional terms are based on the assumption that the body is in the


anatomical position.

Lateral-Medial

– Lateral – Away from the midline of the body

Midline

LateralMedial

– Medial – Toward the midline


– E.g., Your ears are lateral to your cheeks and your cheeks are medial to your ears

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Distal-Proximal

– Distal – Further from some specified region

– Proximal – Closer to some specified region

– E.g., With respect to the trunk, the hands are distal to the arms and the


hands are distal to the arms and the arms are proximal to the hands.

– E.g., With respect to nerves and blood vessels, proximal also means "toward the origin" and distal means "away from the origin"

– E.g., The colon is the distal portion and stomach is the proximalportion of the digestive tract

Thigh is proximal to the leg

Leg is distal to the thighLeg is proximal to the foot

Foot is distal to the leg

Anterior-Posterior

– Anterior – In front of or front of your body

Anterior Skeleton

– Posterior – Behind or back of your body

– E.g., Your lips are anterior

Posterior Skeleton


to your teeth and your teeth are posterior to your lips

– E.g., In the anatomicalposition, your palms arefacing anteriorly

Superior-Inferior

– Superior – AboveThe collar bone is superior to the rib cage

– Inferior – Below

– E.g., Your lips are i t hi d

The hip bone isinferior to the ribcage


superior to your chin and your chin is inferior to your lips

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Supine– Lying on the back – E.g., Performing a

bench press


Prone– Lying face down – E.g., Preparing to

perform a push-up

Planes of the Body


Imaginary flat surfaces that divide the human body

They are used to:

Planes


– divide the body for further identification of particular areas

– describe different movements or actions

Always refer to the body in the anatomical position

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Median plane or midsagittal plane

– A vertical plane that bisects the body into equal right and left halves

MedianPlane


– Sagittal plane is any plane parallel to the median plane

Coronal plane or frontal plane

– A vertical plane that bisects the body into f t d b k

Coronal Plane


front and back

– It is at right angles tothe median plane

Transverse plane or horizontal plane

– A horizontal plane that bisects the body into top and bottom


into top and bottom

– It is at right angles to both the median and coronal planes

Transverse Plane

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Center of gravity– The point at which

the median, frontal,


the median, frontal, and transverse planes intersect

Movements


Movement around a joint may be around any one (or more) of three axes

X

Y

Z


Most movements are found in pairs – for every movement, there is generally a movement that is opposite to it

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Flexion-ExtensionFlexion – reduces the angle between two bones at a jointExtension – increases the angle between two bones at a joint

Flexion


Usually a sagittal plane movement

E.g., Biceps curl– Lifting the weight reduces the

angle at the joint = flexion– Lowering the weight increases the

angle at the join = extension Extension

Dorsiflexion-Plantar flexionModified flexion with respect to the ankle joint

Dorsiflexion – bringing Dorsiflexion


the top of the foot toward the lower leg or shin

Plantar flexion –“planting” the foot

Plantar Flexion

Abduction-Adduction

Abduction

Abduction – moving a segment away from the midline of the body

Adduction – moving segment toward the midline of the body


Frontal plane movement

E.g., The motions of the arms and legs during a jumping jack

Hint: – Abduct = “take away” from the midline– Adduct = “add” toward the midline Adduction

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CircumductionA cone of movement that does not include any rotation

Occurs when flexion-extension movements are combined with


movements are combined with abduction-adduction movements

E.g., Tracing an imaginary circle in the air with your index finger – The tip of your finger represents

the base of the cone, while your knuckle forms the apex of this conical motion

Rotation

Turning a bone along its longitudinal axis

Medial rotation rotation


Medial rotation – rotation toward the midline

Lateral rotation – rotation away from the midline

Pronation-supination

Movements related to the forearm and hand

Pronation – when the palm is P ti


Pronation – when the palm is moved to face posteriorly

Supination – when the palm is moved to face anteriorly (Hint: you can hold a bowl of soup)

Pronation

Supination

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Inversion-Eversion

Movements related to the sole of the foot

Inversion – When the sole is


turned inward (as when you "go over" on your ankle)

Eversion

Inversion

Eversion – When the sole is turned outward or away from the median plane of the body

The Musculoskeletal System



The Bare Bones ofHuman Anatomy

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The function of the skeletal system is to:

– provide a supporting framework– protect body organs


Bone is a living tissue complete with blood supply and nerves


Bone

Bone Shape

The shapes of the bones allow them to perform specific functions more effectively


effectively

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Short Bones:– Include bones of ankle (i.e., tarsals) and wrist

(i.e., carpals)– Serve as good shock absorbers


Carpals

Tarsals

Long bones:

– Include femur of the thigh, humerus of the upper arm, and others

Femur Humerus


– Any bone whose length greatly exceeds its diameter

– Provide levers for movement

Flat bones:

– Include bones of the skull, scapula, ribs, sternum, and clavicle

– Largely protect underlying organs


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Irregular Bones:– Include bones of your face and vertebrae– Bones that cannot be placed in other groups– Fulfill special functions


Facial bones

Vertebrae

Sesamoid bones:– Includes the patella

Oval shape like a pea


– Oval shape, like a pea, and found in tendons

Patella

Bone is very strong for its relatively light weightThe major components of bone are:

Bone CompositionCortical Bone

Spongy Bone


of bone are:– Calcium carbonate– Calcium phosphate– Collagen– Water

Medullary (marrow) cavity

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Bone CompositionCalcium carbonate and calcium phosphate:– Make up 60 to 70 percent of bone weight– Provide much of the bone’s stiffness and resistance to pressing or

squeezing forces

Collagen (a protein):


Collagen (a protein):– Gives bone its characteristic flexibility and contributes to its

ability to resist pulling and stretching forces – With aging, collagen is lost progressively and bone becomes

more brittle.

Water– Bone consists of much smaller proportion of water than other

body parts

Bone Classification

According to the degree of porosity, bone can be classified into two general categories:


– Cortical bone (low porosity)

– Spongy or cancellous bone (high porosity)

Cancellous bone Compact Bone

Porosity High (Low mineral content and high collagen)

Low (High mineral content and low collagen)


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Structure Honey comb Compact







Characteristic Provides more flexibilitybut is not as stress resistant

Stiffer and can resist greater stress but less flexible








Function Shock absorption due to its better ability to change shape

Withstanding stress in body areas that are subject to higher impact loads

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Function Shock absorption due to its better ability to change shape are important

Withstanding stress in body areas that are subject to higher impact loads

Location e.g., vertebrae Long bones (e.g., bones of the arms and legs)

Effect of Fitness on BoneWhen bones are subjected to regular physical activity and habitual loads, they tend to become more dense and more mineralized– E.g., Right forearm bones of right-handed tennis

players are more dense than their left ones due to more


players are more dense than their left ones due to more frequent use

Inactivity works in the opposite direction, leading to a decrease in weight and strength. – E.g., Loss of bone mass has been noted in bed-ridden

patients, inactive senior citizens, and astronauts

The Human Skeleton


Skeleton

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Axial Skeleton


Skull

Sternum

Ribs

Vertebral Column

Axial Skeleton


Skull

Divided into two parts:

a) Calvaria


a) Calvaria

b) Face

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a) Calvaria

Frontal BoneParietal Bone


Temporal Bone

Occipital Bone

CalvariaMay be fractured in blows to the skull (e.g., being checked and hitting the skull on the ice in hockey)


Temporal bone:– Most fragile of the calvaria bones – Overlies one of the major blood

vessels – If fractured and displaced internally

= medical emergency (picture)

b) Facial Bones


Lacrimal Bone

Nasal Bone

Maxilla Bone

Mandible Bone

Zygomatic Bone

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Facial Bones

Often broken in contact sports due to rough impact


Some fractures of the maxilla (upper jaw) can leave the lower face separated from the upper face

Vertebral Column7 Cervical Vertebrae (of the neck)

12 Thoracic Vertebrae (of the chest)

Lumbar vertebra, superior view


Sacrum (mid-line region of buttocks)

Coccyx (4 or 5 fused vertebrae of the tail bone)

5 Lumbar Vertebrae (of the lower back)

Lumbar vertebra, lateral view

Vertebral Column

Vertebrae are arranged in a cylindrical column interspersed with fibrocartilaginous (intervertebral) discs


Function:– Provides strong and flexible support for the body and

the ability to keep the body erect– The point of attachment for muscles of the back– Protects the spinal cord and nerves– Absorbs shock through the intervertebral discs without

causing damage to other vertebrae

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RibsTwelve pairs

Made up of :Bone


– Bone– Cartilage, which strengthens the chest cage and

permits expansion

Curved and slightly twisted, making them ideal for protecting the chest area

RibsAll 12 pairs of ribs articulate with the twelve thoracic vertebrae posteriorlyClassified into three groups based on anterior attachment:– True ribs


• 1-7• attach to both the vertebrae and the sternum

– False ribs • 8-10 • attach only to the sternum indirectly, through 7th rib

– Floating ribs• 11 and 12 • attach only to the vertebral column

The Ribs

Manubrium

Sternal BodyTrue Ribs


Xiphoid Process

Costal Cartilages

(1-7)

False Ribs(8-10)

Floating Ribs(11-12)

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SternumMid-line breast bone The clavicles and ribs one to seven articulate with the sternum


Sternum – comprised of the manubrium, sternal body, and xiphoid process

Appendicular Skeleton


Consists of:1. The pectoral girdle (chest)

2 h li b

Appendicular skeleton


2. The upper limb

3. Pelvic girdle (hip)

4. The lower limb

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1.Pectoral Girdle

Consists of: – Scapula (shoulder blade) – Clavicle (collar bone)


Allows the upper limb great mobilityThe sternoclavicular joint is the only point of attachment between the axial skeleton and the pectoral girdle

2. Upper LimbHumerus– The arm bone – Shoulder to elbow

R di d Ul


Radius and Ulna– The forearm bones– Elbow to wrist– Radius is located on the thumb side

of the hand– When you pronate the forearm, the

radius is actually crossing over the ulna – try it yourself

Upper Limb

Carpals

MetacarpalsProximal Phalanx


Phalanges

Middle PhalanxDistal

Phalanx

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3. Pelvic GirdleFormed by pair of os coxae (hip bones)

Supports the bladder and abdominal contents


Attachment:– Posteriorly – join with the sacrum – Anteriorly – join to each other– Laterally – join to the head of thigh

bone (femur) in a cup-shaped acetabulum

4. Lower Limb

Femur – Thigh bone – From hip to knee


Patella – Knee cap– Sesamoid bone in the tendon

of the quadriceps (thigh)muscles

Lower Limb

Tibia and Fibula– Leg bones– From knee to ankle– Tibia is medial and fibula is lateral


Medial malleolus and Lateral malleolus– The distal ends of the tibia and

fibula, respectively– Commonly referred to as the "ankle

bones"– Can be easily palpated

Medialmalleolus

Lateralmalleolus

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Lower LimbTarsals– Ankle bones– Calcaneus or heel bone– Talus

Metatarsals

Calcaneus

Talus


Metatarsals – 5 bones of the foot – Unite with the toes

Phalanges– Toe bones– Three per toe, except the big

toe – proximal, middle, and distal

Phalanges

Metatarsals

Tarsals

Joints of the Human BodyJoint Classification Naming Joints:


Synovial Joints– Characteristics of

synovial joints– Types of synovial joints

– Pectoral Girdle– Upper Limb– Pelvic Girdle– Lower Limb

A joint is a point of connection between two bones

Strands of connective tissue and ligaments hold the bones together and ensure the stability of joints


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Joint ClassificationJoints are classified according to their motion capabilities:

– SynarthrosesImmo able


• Immovable

– Amphiarthroses• Slightly movable

– Diarthroses• Allow the greatest amount of motion

Joint ClassificationJoints are further classified by the material that joins them:

– Fibrous joints• Allow no movement• E g sutures of the skull


E.g., sutures of the skull

– Cartilaginous joints• Allow limited movement• E.g., intervertebral discs

– Synovial joints• Allow large range of movements• E.g., knee joint

Characteristics of Synovial JointsHyaline cartilage– A protective layer of dense white connective tissue that covers

the ends of the articulating bonesJoint cavitySynovial membrane– Covers joint cavity, except over the surfaces of the articular

cartilage


cartilage– Secretes the lubrication fluid

Synovial fluid– Lubricates the joint

Capsule– May or may not have thickenings called intrinsic ligaments

Extrinsic ligaments– Support the joint and connect the articulating bones of the joint

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Types of Synovial Joints

There are three basic types of synovial joints:

– Unilateral (rotation about only one axis)


Unilateral (rotation about only one axis)

– Biaxial joints (movement about two perpendicular axes)

– Multiaxial joints (movement about all three perpendicular axes)

Types of Synovial Joints

Synovial are further classified into:

1. Hinge Joint2 Pi t J i t


2. Pivot Joint3. Condyloid Joint4. Saddle-shaped joint5. Ball and Socket Joint6. Plane Joint

1. Hinge (Ginglymus) Joint

Uniaxial

Has one articulating surface that is convex and


surface that is convex, and another that is concave

E.g., humero-ulnar elbow joint, interphalangeal joint

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Pivot Joint

Uniaxial

One bone rotates around


one axis

E.g., head of radius rotating against ulna

Condyloid (Knuckle) JointBiaxial (flexion-extension, abduction-adduction)The joint surfaces are usually ovalOne joint surface is an ovular convex shape, and the other is a reciprocally shaped concave surface


p y pE.g., metacarpophalangeal joint

Saddle JointBiaxial (flexion-extension, abduction-adduction)

Th b t t th i itti


The bones set together as in sitting on a horse

E.g., carpometacarpal joint of the thumb

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Ball and Socket JointMultiaxial (rotation in all planes)A rounded bone is fitted into a cup-like receptacleE h ld d hi j i t


E.g., shoulder and hip joints

Plane (Gliding) JointUniaxial (permits gliding movements)The bone surfaces involved are nearly flatE.g., intercarpal joints and acromioclavicular joint


acromioclavicular joint

Joints of the Pectoral Girdle


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Sternoclavicular JointConnects the clavicle to the sternumThe only joint connecting the pectoral girdle to the axial skeleton True synovial joint strengthened by an intracapsular disc and extrinsic ligaments


intracapsular disc and extrinsic ligaments

Acromioclavicular JointUnites the lateral end of the clavicle with the acromion process of the scapula

Where shoulder separations often occur in


sports such as hockey, baseball, and football

Glenohumeral JointConnects the upper limb and the scapulaTypical multiaxial jointWide range of movement at this jointCompromise = relative lack of stability


p y

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Joints of the Upper Limb


pp

Elbow JointThere are three joints at the elbow: – Humero-ulnar joint

• Medial• Between the trochlea of the humerus and the

olecranon process of the ulna


olecranon process of the ulna– Humero-radial joint

• Lateral• Between the capitulum of the humerus and the head

of the radius– Radio-ulnar joint

• Between the radius and the ulna

Elbow Joint

Humerus


Ulna

Radius

Humero-Radial Joint

Humero-Ulnar Joint

Radio-Ulnar Joint

Anterior View Posterior View

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Joints of The WristRadio-carpal joint– Between distal end of the radius and the carpals– Movements: Flexion-extension and abduction-

adduction


Joints of the Hand

Intercarpal joints– Between the bones of the carpus– Gliding joints


Carpometacarpal joint– Between carpals and metacarpals– The characteristics of

carpometacarpal joint of the thumb allows the range of movement necessary for opposition

Joints of the HandMetacarpophalangeal joints– Joints between metacarpals

and carpals– The knuckles – Movements: Flexion-


– Movements: Flexion-extension and abduction-adduction

Interphalangeal joints– Joints between the phalanges – Permit flexion-extension

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Joints of the Pelvic Girdle


Joints of the Pelvic Girdle

Hip Joint- Between the head of the femur

and the cup (acetabulum) of the hip bone (os coxae)

Lik th h ld j i t th hi


– Like the shoulder joint, the hip joint is a:

• ball and socket joint

• multiaxial joint that allows flexion-extension, abduction-adduction, and circumduction

Hip JointUnlike the shoulder, the hip joint is very stableThe most stable synovial joint due to:– deepened socked (via lip or fibrocartilaginous


labrum )– an intrinsic and very strong extrinsic ligaments

Dislocation in sports is not common, but can occur in car collisions Dislocate the head posteriorly or drive it through the posterior lip of the actetabulum

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Lower Limb Joints


Lower Limb Joints

Knee JointTibiofemoral or knee joint

Incredible range of movement (flexion –extension)


Knee Joint

The knee joint is relatively stable due to additional structural supports from: – Menisci

Sh k b bi fib il i di


• Shock-absorbing fibrocartilaginous discs– Anterior and posterior cruciate ligaments

• Located in the center of the joint– Lateral and medial collateral ligaments

• Extend from the sides of the femur to the tibia and fibula

– Musculature that surrounds it

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Knee Joint

Movements:– Primary action is flexion-extension (e.g., squat

or jump)– When flexed medial and lateral rotation can


When flexed, medial and lateral rotation can also occur

Ankle JointTalocrural or ankle jointIncludes several bones:

– Medial and lateral

Medial malleolus

Lateral malleolus

Talus


malleoli of the tibia and fibula

– Head of the talus– Calcaneus (heel bone)

TalusCalcaneus

Foot and Toe JointsIntertarsal joints– Between tarsals– Transverse tarsal joint

• Between the proximal and distal row of tarsal bones• Movement: inversion-eversion of the sole of the foot


Movement: inversion eversion of the sole of the foot• This action enables you to adjust to uneven ground when

walking or running

Tarsals

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Foot and Toes JointsAs in the hand, there are joints between the tarsal bones, metatarsals, and phalanges:


– Tarsometatarsal– Metatarsophalangeal– Interphalangeal

• Strengthened by plantar ligaments, which aid in maintaining the arch of the foot

Tarsometatarsal

Metatarsophalangeal

Interphalangeal

Muscles of the Human


Body

Over 600 muscles in the human body

Allow the skeleton to move

Both ends of a muscle must be attached to


Both ends of a muscle must be attached to bone to create movement– Origin or proximal attachment: the attachment

closer to the center of the body – Insertion or distal attachment: the attachment

away from the center of the body

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Facial Muscles


Various functions of the facial muscles: – Enable you to change expression and display

emotions visibly– Allow you to close your eyes and blink– Essential for opening and closing the mouth for:

• keeping food in the mouth• chewing


• forming words

Tongue – Functions:

• allows you move food around in your mouth and get it to a position to be swallowed

• allows you to pronounce words and speak intelligibly

Neck Muscles


Neck Muscles

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There are muscles posterior, lateral, and anterior to the neck or cervical region

Th l

Neck Muscles


These muscles:– Maintain the position of the head on the 1st

cervical vertebra (atlas), i.e., they hold up our head

– Also permit a wide range of movement

Sternocleidomastoids

The most important anterior pair of muscles

M t


Movements:– Acting together, they flex

the head toward the chest– Individually, each muscle

tilts the face up and toward the opposite side

Erector spinae musclesImportant posterior neck muscles

Attach to sacrum inferiorly and to the skull superiorly


Maintain your erect position– Also called anti-gravity

muscles– When someone faints, these

muscle no longer function and the body falls face forward to the ground

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Trapezius, upper fibersImportant lateral neck muscles

Movements:– Acting alone tilt the head to the one side


Acting alone, tilt the head to the one side– Together, assist in neck extension

Trapezius upper fibers

Muscles of the Pectoral Girdle


Muscles of the Pectoral Girdle

Muscles acting to hold the pectoral girdle to the chest wall:

Anterior– Pectoralis Major– Pectoralis Minor– Subclavius


– Serratus Anterior Posterior– Trapezius– Latissimus Dorsi– Levator Scapulae– Rhomboids Major– Rhomboids Minor

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Pectoral Girdle – Anterior

Pectoralis Major


Pectoralis Minor

Serratus Anterior

Pectoral Girdle – Posterior

Trapezius (upper fibers)

Trapezius (middle fibers)

Rhomboids


Teres Major

Trapezius (lower fibers)

Latissimus Dorsi

Rhomboids

Muscles that attach from the scapula to the humerus and act across the shoulder joint:

Anterior– Subscapularis

Posterior


Posterior – Supraspinatus– Infraspinatus– Teres Minor– Teres Major

Lateral– Deltoid

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Subscapularis

Anterior Lateral

Deltoid (anterior fibers)

Deltoid (middle fibers)


(middle fibers)

Deltoid (posterior fibers)

Superior and Posterior

Supraspinatus

Infraspinatus

Teres Minor


Teres Minor

Combined with Subscapularis, these muscles are the rotator cuff muscles

Can be remembered by using the mnemonic

SSIT

Muscles of the Arm


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Anterior Compartment

Biceps Brachii– Attaches:

• proximally to distal part of humerus (short head)

Biceps Brachii


• distally to proximal part of ulna (together with long head)

– Movements of the arm:• Flexor of the elbow joint • Supinator of the forearm

Biceps Brachii

Anterior Compartment

Brachialis– Attaches:

• proximally to the anterior surface of the humerus

Brachialis


• distally to the coronoid process of the ulna

– Movements of the arm:• Powerful flexor of the elbow

joint• Works with the biceps brachii

Brachialis

Posterior Compartment

Triceps Brachii– Attaches:

• proximally to humerus (medial and lateral head)


and lateral head)• distally to the olecranon process

of the ulna (together with long head)

– Movement of the arm:• Elbow extensor

Triceps

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Muscles of the Forearm


Forearm muscles act on the elbow, wrist, and digits (fingers)

Flexor-pronator group – Attached to the medial epicondyle of the


humerus

Extensor-supinator – Attached to the lateral epicondyle of the

humerus

Flexors of the forearm


Anterior View Posterior View

Extensors of the forearm

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Muscles of the Pelvic Girdle


Anterior Muscles

Iliopsoas


Posterior and Lateral MusclesGluteals – Include 3 muscles:

• Gluteus maximus– Largest of the three

muscles– Principal extensor of the

hi

Gluteus Medius


hip• Gluteus medius and

minimus– Assist in hip extension– Abduct the hip

Lateral or external rotators of the hip– Six little muscles

Gluteus Maximus

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Thigh Muscles


g

Pectineus

Adductor Brevis

Adductor Longus

Medial Compartment

Pectineus GracilisAdductors:

Adductor longus


Adductor Magnus

Gracilis

– Adductor longus– Adductor brevis– Adductor magnus

Primary action: adduct the thigh toward the midline

Anterior CompartmentQuadriceps– Rectus femoris– Vastus lateralis– Vastus intermedius– Vastus medialis

Sartorius


Sartorius– Lies anterior to the quads– Used to sit cross-legged

Primary knee extensors Sartorius and Rectus femoris also aid in flexion of the hip

Vastus Lateralis

Vastus Intermedius

Vastus Medialis

Rectus Femoris (cut)

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Posterior Compartment Hamstrings composed of three muscles:– Biceps femoris (2 heads)– Semitendinosus– Semimembranosus

Long Head


Attach:– proximally to the ischial tuberosity – distally, biceps femoris to the head

of the fibula and semitendinosus and semimembranosus to the tibia

Primary flexors of the kneeAlso extend the hip

Short Head of Biceps Femoris

Long Head of Biceps Femoris

Semitendinosus

Semimembranosus

Leg Muscles


Leg Muscles

Anterior CompartmentTibialis anteriorExtensor hallucis longus (deep)Extensor digitorum (deep)Arise from:

– anterolateral surface of the tibia– interosseous membrane between the tibia and

the fibulaanterior surface of the fibula

Tibialis Anterior


– anterior surface of the fibulaCross anterior to the ankle jointAttach distally to:

– medial side of the foot– distal phalanges of the digits

Movements:– Primary dorsiflexors of the ankle– Extensors of the toes– Tibialis anterior further inverts the foot– Peroneus tertius assists in eversion

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Lateral CompartmentPeroneus longusPeroneus brevisAttach proximally to the lateral surface of the tibiaP b hi d h l l

Peroneus Longus


Pass behind the lateral malleolusAttach distally to the footMovements:– Plantar flexors – Evert the sole of the foot

Peroneus Brevis

Posterior CompartmentSuperficial group– Gastrocnemius

• has two proximal heads • attaches proximally to the

medial and lateral epicondyles of the distal femur

Gastrocnemius


– Soleus • attaches proximally to

proximal ends of tibia and fibula

– Gastrocnemius and soleus come together to form the Achilles tendon

– Principal plantar flexors of the ankle

Soleus

Achilles Tendon

Posterior Compartment

Deep group

P i l i fl i f th t


– Primary role is flexion of the toes

– Assist in plantar flexion of the ankle

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Muscles of the Abdomen


ObliquesExternal obliqueInternal oblique Transversus abdominisReach from the vertebral column, ribs, and hip bone posteriorlyMeet in the midline anteriorly through rectus abdominis

External obliqueInternal oblique


through rectus abdominisFunctions:

– Lateral bending of the abdomen

– Rotation of the abdomen – Extension of the abdomen

during forced inspiration– Allow the development of a

pregnant uterus– Contract to help expel fecal

contents from the rectum

Transversus abdominis

Rectus AbdominisPaired midline muscles

Powerful flexor of the anterior abdominal wall

Rectus Sheath


Strengthening of the abdominal muscles is a very important part of back therapy, because the abdominals act to support the back

Rectus Abdominis

Linea alba

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SummaryHuman anatomy deals with the structures that make up the human body (structure determines function)The bones, joints, and muscles that make up the musculoskeletal system allow numerous movements to occur, with varying degrees of:

Motion capabilities


– Motion capabilities– Strength– Flexibility

Bones provide the structural framework necessary for supportMuscles supply the powerJoints supply the mechanism that allows human movement to occur

Discussion Questions1. Describe the anatomical position and discuss its relationship to the

directional terms of the body.2. What are the four major planes that bisect the body? Provide an example of

a movement that occurs in each plane.3. Define three types of movement and give an example of each.4. Name the three types of muscle. How do slow twitch and fast twitch fibbers

differ?


5. Differentiate among agonists, antagonists, and synergists. What role is played by the fixators?

6. Which synovial joints allow the greatest amount of movement? The least?7. Outline the components and roles of the axial and appendicular skeletons.8. What structures present at the knee provide additional support to this joint? 9. What type of joint is the knee?10. What muscles are primarily responsible for maintaining an upright posture?11. The posterior group of leg muscles are commonly called the hamstrings.

What three muscles combine to form the hamstrings? What role do they play?

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