A&P Lab 10 - Class 9: Joints and the Muscular System

Which two ways could joints be classified?

* Function
* Structure

What is the functional classification of joints based on?

The amount of movement that can occur at the joint.

What are the 3 basic types of joints based on functional activity?

* Synarthroses (immovable joints).
* Amphiarthroses (slightly movable joints).
* Diarthroses (freely movable joints).

How many words are functional classifications of joints?

1 word

How many words are structural classifications of joints?

Multi-word

Fibrous joints

* The articulating bones are firmly bound together by dense fibrous connective tissue.
* The joints are very strong, and permit little to no movement.
* A joint cavity is not present.

2 major types of joints in the fibrous joint structural division

* Sutures:
* Articulating bones are held very close together by dense connective tissue.
* Functionally classified as synarthroses (immovable).
* Syndesmoses:
* The articulating bones are united by a band of dense connective tissue.
* The amount of movement at this type of joint depends upon the length of the connective fibers.

Cartilaginous joints

Articulating bones are bound to each other by cartilage. These joints lack a joint cavity, and permit little or no movement.

Two major types of joints in the cartilaginous joint structural division

* Synchondroses:
* Articulating bones are connected by hyaline cartilage.
* Functionally classified in the adult as synarthroses (immovable).
* Symphyses:
* Articulating bones are connected to fibrocartilage.
* Functionally classified as amphiarthroses (slightly movable).

Bones articulated distally

Talus

Synovial joints

* Makes up most joints in the body.
* The movement of these joints are limited only by ligaments, muscles, tendons, or adjoining bones.
* Characterized as diarthroses (freely movable).

Distinguishing features of a synovial joint

* Articulating bones separated by a fluid-filled joint cavity.
* Articular cartilage (hyaline) covers the surface of the articulating bones.
* Joint cavity is enclosed by an articular capsule, consisting of an outer layer, the fibrous capsule, and an inner layer, formed by the synovial membrane.
* Synovial membrane secretes synovial fluid, which fills the synovial cavity, lubricates the joint, and provides nourishment for the articular cartilage.
* Reinforced and strengthened by band-like ligaments composed of dense regular connective tissue.

What are the categories that synovial joints can be divided into?

* Plane (gliding) joints
* Hinge joints
* Pivot joints
* Condyloid (Ellipsoid) joints
* Saddle joints
* Ball-and-socket joints

Plane (gliding) joints

A synovial joint sub-category.

* Articulating surfaces are essentially flat.
* Movement doesn’t occur around an axis (nonaxial); only allows slight movement.

Hinge joints

A synovial joint sub-category.

* A convex surface of one bone fits into the concave surface of another bone.
* Movement occurs around a single axis (monaxial); permits flexion and extension.

Which type of synovial joint do the following joints belong to:

* Sternocostal joint
* Vertebrocostal joint
* Intervertebral joint
* Joint between tarsals and metatarsals

Plane (gliding) joint

Which type of synovial joint do the following joints belong to:

* Elbow joint
* Joint between the phalanges
* Ankle joint
* Knee joint

Hinge joint

Pivot joints

A synovial joint sub-category.

* A rounded surface of one bone fits into a ring-like portion of another bone.
* Movement occurs around a single axis (monaxial); permits rotation.

Nonaxial

Movement (of a joint) does not occur around an axis

Monaxial

Movement (of a joint) occurs around a single axis

Which type of synovial joint do the following joints belong to:

* Joint between the atlas and axis
* Joint between the head of the radius and the ulna

Pivot joint

Condyloid (Ellipsoid) joints

A synovial joint sub-category.

* An oval convex surface of one bone fits into an oval concave surface of another bone.
* Movement occurs around 2 axes (biaxial); permits all angular motions: flexion and extension, abduction and adduction, and circumduction.

Biaxial

Movement (of a joint) around two axes, permitting all angular motions.

Which type of synovial joint do the following joints belong to:

* Joint between the radius and carpal bones
* Metacarpophalangeal and metatarsophalangeal joints between the metacarpals/metatarsals and phalanges

Condyloid (Ellipsoid) joints

Saddle joints

A synovial joint sub-category.

* Each articular surface has both convex and concave areas; the surface of one bone fits as a “rider” into the “saddle” of the other bone.
* Movement occurs around 2 axes (biaxial); permits all angular motions: flexion and extension, abduction and adduction, circumduction and rotation.

Which type of synovial joint does the following joint belong to:

* Joint between the carpal and metacarpal bone of the thumb

Saddle joint

Ball-and-socket joints

A synovial joint sub-category.

* A ball-like surface of one bone fits into a cup-like depression of another bone.
* Movement occurs in all axes and planes (multiaxial and triaxial); permits all angular and rotation motions: flexion and extension, abduction and adduction, circumduction and rotation.

Which type of synovial joint do the following joints belong to:

* Shoulder joint
* Hip joint

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Ball-and-socket joint

Abduction

The movement of a limb or other body part away from the medial line of the body (caused by the contraction of an abductor muscle).

Adduction

The movement of a limb or other body part toward the medial line of the body (caused by the contraction of an adductor muscle).

Flexion

A bending movement that decreases the angle between articulating bones (caused by the contraction of a flexor muscle).

* Two special terms are applied to flexion of the foot and ankle joint:
* Dorsiflexion: Toes point upward (when you stand on your heels).
* Plantar flexion: Toes point downward (as when you stand on “tiptoe”).

Extension

A bending movement that increases the angle between articulating bones; straightening or extending a limb (caused by the contraction of an extensor muscle).

Hyperextension

The continuation of extension beyond anatomical position.

Rotation

The movement of a bone around its own longitudinal axis without lateral displacement of the body part.

Circumduction

The movement in which one end of a limb remains relatively stationary while the distal end of the limb moves in a circle.

Pronation

The movement of the hand from a palm-up to a palm-down (prone) position.

Can also refer to movements that place the body in a face-down (prone) position.

Supination

The movement of the hand from a palm-down to a palm-up (supine) position.

Can also refer to movements that place the body in a face-up (lying on back) position.

* Two special terms are applied to unique movements of the foot:
* Eversion: The movement in which the soles are turned outward (laterally).
* Inversion: The movement in which the soles of the foot turn inward (medially).

Hold your hand straight out from the shoulder and move your hand in a circle.

What’s this movement called?

Circumduction

Stand with your hands at your side, palms toward the midline. Turn your palms forward. Which movement is this?

Supination

Turn your palms from forwards to backwards.

Which movement is this?

Pronation

Which joint are you using to rotate your palms forward and backward?

The joint between the radius and the ulna

Turn the soles of your feet away from each other, what is this movement?

Eversion

Turn the soles of your feet toward each other.

What’s this movement called?

Inversion

Bend your arm so that your fingers touch your shoulder. What time of movement is occurring at your elbow?

Flexion

If you straighten your arm, which movement is involved?

Extension

Stand with your feet together, and move your right leg away from your left leg using the hip joint.

Name the movement.

Rotation

Glenohumeral joint

Shoulder joint.

Ball and socket joint formed by the articulation of the head of the humerus with the glenoid cavity of the scapula.

Explain characteristics making the shoulder joint unique

* Has the greatest range of motion of any joint in the body.
* The most unstable joint, prone to dislocation.
* Allows for flexion, extension, hyperextension, abduction, adduction, medial and lateral rotation, and circumduction of the arm.

What is the type of movement of the shoulder joint due to?

The loose articular capsule and shallow glenoid cavity in relation to the large size of the head of the humerus.

a) What is the shoulder joint stabilized by?

b) “Superstabilizer” tendon of the bicep muscle

a) Rotator cuff muscles whose tendons fuse with the articular capsule to hold the humerus in place.

b) Secures the head pf the humerus against the glenoid cavity

Glenohumeral ligaments

* Between the coracoid process of the scapula and humeral head.
* Is a thickening of the superior part of the articular capsule.
* Extends in between the coracoid process and acromion.

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Coracohumeral ligament

Three thickenings of the anterior part of articular capsule.

a) Where is the synovial plantar joint found?

b) Which ligaments provide stability for this joint?

a) Between the lateral end of the clavicle and the acromion process of the scapula.

b)

Superiorly: acromioclavicular ligament. Extends between the clavicle and acromion process.

Coracoclavicular ligament: Binds the clavicle to the coracoid process of the scapula.

a) How many bursae are associated with the shoulder joint?

b) Explain what these are

a) 4

b) Flattened fibrous sacs lined with a synovial membrane, and contain synovial fluid to help decrease friction on the shoulder where tendons and muscles cross the joint capsule.

a) What type of joint is the knee joint?

b) Why is it classified as this?

c) How many bursae are found within this joint?

a) Synovial hinge joint

b) Movements are limited to extension, flexion, and some rotation by the surrounding ligaments

c) At least a dozen

What is the largest weight-bearing surface in the body?

The flat surface of the tibia.

What is a common knee injury amongst athletes?

Torn or loose menisci (two crescent-shaped fibrocartilage pads).

How do the anterior and posterior cruciate ligaments add stability to the knee joint?

They extend diagonally from the superior surface of the tibia to the distal end of the femur, between the condyles.

Explain how the anterior and posterior cruciate ligaments work when a leg is extended vs. flexed

* Knee is extended: Anterior cruciate ligament is taut, thus preventing overextension of the joint.
* Knee is flexed: Posterior cruciate ligament becomes taut, preventing the knee from slipping posteriorly.

Which ligaments reinforce the capsule of the hip joint?

* Iliofemoral ligament
* Pubofemoral ligament
* Ischiofemoral ligament

Ligamentum teres

Ligament concealed inside the joint, and contains vessels that supply the head of the femur

Function of synovial fluid

* Lubrication to provide friction
* Allows for smooth movement
* Shock absorption
* Cushioning of joints

What is the function of the ligaments surrounding a joint?

* Reinforce and strengthen
* Limit rotation at joint
* Support wall of joint to prevent unwanted movement

Bursitis

Inflammation of the bursa (fluid-filled sac of the knee)

Tendonitis

Inflammation of the tendons

Arthritis

Inflammation of the joints

What kind of joint (structure and function):

The bodies of the vertebrae

* Structure: Cartilaginous symphysis
* Function: Amphiarthrosis (slightly movable)

What kind of joint (structure and function):

The coxa and the femur

* Structure: Synovial ball and socket
* Function: Diarthrosis (free movable)

What kind of joint (structure and function):

The coxa and the sacrum

* Structure: Synovial plane
* Function: Diarthrosis (free movable)

What kind of joint (structure and function):

The occipital bone and the atlas

* Structure: Synovial condyloid
* Function: Diarthrosis (free movable)

What kind of joint (structure and function):

The carpal and the metacarpal of the thumb

* Structure: Synovial saddle joint
* Function: Synarthrosis (immovable)

What kind of joint (structure and function):

Frontal and parietal bones

* Structure: Fibrous suture
* Function: Synarthrosis (immovable)

How many skeletal muscles are within the muscular system?

Around 700

True or False:

Individual skeletal muscles are organs that also contain connective and nervous tissue

True

Characteristics of a skeletal muscle fibre

* Long, thick, cylindrical cell
* Ends of muscle fibers are blunt (cells don’t taper)
* Multiple, peripherally located nuclei
* Striations are visible within each fiber
* Voluntary and requires a stimulus to contract
* Supplied with a nerve ending of a somatic motor neuron

All the fibres controlled by a single motor neuron constitute a:

Motor unit

The site of communication between a neuron and muscle cell

A synapse

True or False:

All skeletal muscles are attached to bones

False.

Most are, but not all

a) Origin vs. insertion of a muscle

b) What is the belly?

a)

Origin: Bony sight of attachment of a muscle at the relatively stationary end of the bone.

Insertion: The attachment site of the bone which moves.

b) The middle, thicker region of the muscle.

Prime mover/agonist

The muscle whose contraction is primarily responsible for producing a particular action

As the prime mover _________, another muscle will stretch

Contracts

Antagonist

The muscle that stretches and yields to the effects of the prime mover

Synergists

Muscles which contract at the same time as the prime mover, but are not the prime mover.

They aid the prime mover in producing an effective movement.

Fixators

Stabilize the origin of the prime mover so that the prime mover can act more efficiently.

Muscle location

Indicates a structure located close by the muscle

Direction of the muscle fibers

Indicates orientation of the muscle fibers relative to the midline of the body

Muscle shape

Indicates the distinctive shape of a muscle

Relative size of the muscle

Denote size

Ex. Terms such as maximus, minimus, major, minor, …

Number of divisions in the origin of the muscle

Numbers of origins/heads occurring

Ex. Biceps, triceps, quadriceps, …

Location of the muscle attachments

Can be named according to the points of origin and insertion.

Basis of the muscular action

Indicates the principle action of a muscle

Origin

End of the bone that’s attached to stationary bone.

Insertion

End of the bone that’s attached to movable bone.

Origin (O) and insertion (I):

Masseter

O: Zygomatic arch

I: Lateral surface of mandible

Origin (O) and insertion (I):

Sternocleidomastoid

O: Manubrium of sternum and medial portion of clavicle

I: Mastoid process of temporal bone

Origin (O) and insertion (I):

Pectoralis major

O: Clavicle, sternum, and costal cartilages of upper ribs

I: Humerus

Origin (O) and insertion (I):

Deltoid

O: Acromion process and spine of the scapula, lateral third of the clavicle

I: Deltoid tuberosity of humerus

Origin (O) and insertion (I):

Latissimus dorsi

O: Spinous processes of T7-T12 lumbar and sacral vertebrae, and lower ribs and iliac crest

I: Humerus

Origin (O) and insertion (I):

Triceps brachii

O: Scapula and humerus

I: Olecranon process of ulna

Origin (O) and insertion (I):

Biceps brachii

O: Scapula

I: Radial tuberosity