Anatomy Quiz #3

3 types of functional classification of joints (based on allowed movement)

1. Synarthrosis → immovable

2. Amphiarthrosis → slightly movable

3. Diarthrosis → freely movable (all synovial joints)

3 types of structural classification (by the material that binds bones together & presence or absence of a joint cavity)

1. Fibrous → bones connected by dense connective tissue (fibers); tend to be immovable or only slightly moveable

2. Cartilaginous → bones connected by cartilage; highly moveable

3. Synovial → fluid-filled joint cavity between bones; highly moveable

Which joints have high mobility?

• Diarthroses

• Cartilaginous

• Synovial

3 movements allowed by Synovial Joints

1. Gliding → one bone slides across the surface of another (e.g., at the wrists, ribs 2-7 & sternum)

2. Angular → movements change the angle between bones (e.g., flexion at the knee)

3. Rotation → movement around a bone’s long axis

3 types of Fibrous Joints

1. Suture → very short fibers (e.g., only in the skull)

2. Syndesmosis → ligaments that hold bones together

3. Gomphosis → peg-in-socket joint (e.g., teeth)

What kind of joints are cartilaginous joints?

• Synarthroses (immovable)

Where are cartilaginous joints located?

• Between epiphyseal plates & diaphysis

• Joint between first rib & sternum

What is fibrocartilage?

• Cartilage that unites bones; resists tension & compression

General Structure of Synovial Joints

• All synovial joints are diarthrosis (most mobility)

• Ligament → can also have extracapsular or intracapsular reinforcing ligaments

• Joint cavity → space filled by synovial fluid

• Synovial fluid → viscous-like egg white; acts as a slippery lubricant

• Articular cartilage → hyaline cartilage containing synovial fluid; weeping lubricant

• Fibrous layer → dense, irregular connective tissue

• Synovial membrane → loose connective tissue; makes synovial fluid

• Periosteum → thin sheet of connective tissue; delivers blood & nutrients to bones

What does the articular capsule contain?

• Fibrous layer

• Synovial membrane

• Periosteum

Characteristics of Synovial Joints

• Rich supply of sensory nerves (detects pain & monitors how much the articular capsule is being stretched)

• Rich supply of blood vessels running to synovial membrane; is redundant, if some blood vessels are obstructed by certain joint positions, the joint keeps working

• Filtration from the extensive capillary beds of the blood vessels gives rise to the base fluid for synovial fluid

• Synovial fluid contains glycoproteins that are secreted by fibroblasts

What are the 4 functional types of Synovial Joints?

1. Nonaxial → movement does not occur around a particular axis

2. Uniaxial → movement occurs around a single axis (e.g., finger & elbow)

3. Biaxial → movement occurs around two axes (e.g., movement in both frontal & sagittal planes)

4. Multiaxial → movement occurs around all 3 axes or along all 3 planes (e.g., shoulder)

What are the 2 basic forms of Synovial Joints?

1. Bursa → a flattened fibrous sac lined by a synovial membrane

2. Tendon Sheath → an elongated bursa that wraps around a tendon

What is an example of a Synovial Joint?

Temporomandibular (jaw) joint

3 factors that contribute to stability in Synovial Joints

1. Articular surfaces - seldom deep enough to play a major role (exceptions: hip, elbow, & ankle)

2. Ligaments - more ligaments generally means a stronger, more stable joint, ligaments only stretch 6% in length & then snap; which side of the joint the ligaments are on determines what particular movements are resisted (and stable)

3. Muscle tone - constant, low levels of contractile force to keep tension on the tendons; especially important in the shoulders, knee, & arches of the foot

What terms accurately describe the elbow joints?

Diarthrotic & synovial

What terms accurately describe the joints between the bones of your skull?

Synarthrotic & fibrous

What are muscles?

a complex tissue containing both muscle cells & surrounding connective tissue, it makes up nearly half of the mass of the body

Function of Muscle Tissue

• Produces movement: either body parts moving bones or squeezing substance through organs (ex. the heart)

• Opens & closes body passageways: muscle sphincters function as valves

• Maintains posture 7 stabilize joints: basic muscle tone stabilized many synovial joints, enabling sitting & standing

• Heat generation: contraction of muscles produces heat that help maintain normal body temperature

Properties of Muscle Tissue

• Contractibility: muscle tissue contracts due to the presence of myofilaments containing either actin or myosin (e.g., biceps brachii movement)

• Excitability = irritable: nerve signals cause electrical impulses that initiate contraction

• Extensibility: muscle tissue can be stretched — typically skeletal muscle by an opposing muscle & smooth muscle by substances in the organ containing the smooth muscle (doesn’t break) (e.g., elbow flexing motion)

• Elasticity: after being stretched, muscle tissue passively recoils to resting length

What is sarcolemma?

Plasma membrane of muscle cells

What is sarcoplasm?

Cytoplasm of muscle cells

What are myofibrils?

Strings of actin & myosin filaments that allow your muscles to contract (fiber = cell)

What are skeletal muscles (muscle organs) composed of?

• Connective tissue

• Blood vessels

• Highly innervated

• Contraction

What types of tissue are contained in skeletal muscle (organ)?

• Mostly muscle tissue

• Connective tissue

• Epithelial tissue lining blood vessels

• Nerves

Role of connective tissue sheaths in Skeletal Muscle

Binds a skeletal muscle & its fibers together & extend from it to form a tendon

3 types of sheaths of connective tissue in Skeletal Muscle

1. Epimysium - dense regular connective tissue surrounding the entire muscle (G. epi = on)

2. Perimysium - surrounds each fascicle (group of muscle fibers) (G. peri = around)

3. Endomysium - a fine sheath of connective tissue wrapping each muscle cell (G. endo = inside) (G. mys = muscle mouse, mouse)

What is aponerosis?

Wide, flat tendon

Naming Skeletal Muscles

• Shape (ex. the deltoid is triangular (like Greek delta symbol))

• Relative size (maximus, minimus, & longus indicate size) (e.g., gluteus maximus & gluteus minimus))

• Structure = number of origins (e.g., words “biceps”, “triceps”, & “quadriceps”)

• Location (e.g., brachialis is located on the arm (brachium))

• Attachments (name can reveal points of origin & insertion (e.g., brachiordialis))

• Action (often the action is part of the muscle’s name (e.g., flexor, extensor, adductor. & abductor))

• Direction of fascicles & muscle fibers (name tells direction in which fibers run (e.g., rectus abdominis & transverseus abdominis) (L. rect = straight, L. transvers = transverse))

What are synergists?

Helps the prime mover by adding extra force or by reducing undesirable movements such as controlling the position of intermediate joints (ex. extensors of wrist are synergists for making a fist; for adduction at the shoulder, latissimus dorsi is agonist & pectoralis synertist)

Example(s) of synergists

Extensor carpi ulnaris & flexor carpi ulnaris; they act together to stabilize the wrist

Example(s) of agonists/prime mover

Flexors of pollex (thumb) & digits when you clench your fist or pectoralis major when flexing arm at the shoulder

What are prime movers/agonists?

Muscles that produce the primary action

What are antagonists?

Opposes or reverses a movement

Example(s) of antagonists

Latissimus dorsi in flexing arm at the shoulder, extensors of the pollex (thumb) & digits are antagonists to flexors of the pollex & digits making a fist

What are fixators?

Holds one body part or bone in place while another part is moved

Example(s) of fixators

Rectus abdominal fixes the pelvis when you raise your legs either on the floor or when seated (rectus not involved in primary movement — it runs from the xiphoid & costal cartilages to pubic crests; never makes it to the legs)

What are the 2 types of muscle attachments?

1. Origin - less movable attachment (generally more proximal or nearer the axis of the body)

2. Insertion - more moveable attachment (generally more distal or farther from axis of the body)

Origin & insertion of brachialis

• Origin: humerus (when flexing), radius (when doing chin-ups)

• Insertion: radius (when flexing), humerus (when doing chin-ups)

Origin & insertion of sartorius

• Origin: ilium

• Insertion: proximal end of tibia

Origin & insertion of vastus lateralis

• Origin: on the greater trochanter & intertrochanter line of the femur

• Insertion: ligaments that are around the knee

Origin & insertion of vastus intermedius

• Origin: on greater trochanter & intertrochanter line of the femur

• Insertion: ligaments that are around the knee

Origin & insertion of vastus medialis

• Origin: greater trochanter & intertrochanter line of the femur

• Insertion: ligaments that are around the knee

What are the different ways fascicles can be arranged?

• Circular: fascicles in concentric rings, work as sphincters to close openings (e.g. muscles of the mouth)

• Convergent: origin of muscle is broad & then fascicles converge toward tendon where muscle inserts to give an overall triangular or fan-shaped, fibers run full length of muscle (e.g. pectoralis major)

• Parallel: fascicles run parallel to the long axis of the muscle & fibers run full length of muscle, muscles can be either fusiform with expanded belly (e.g. biceps brachii) or strap-like (e.g. sartoris)

• Pennate: fascicles are short & attach obliquely to a tendon that runs the whole length of the whole muscle; making muscle look like a feather (L. penna = feather) (e.g. extensor digitorum longus)

• Unipennate: if fascicles insert only on ONE SIDE of tendon (L. uni = one) (e.g. rectus femoris)

• Bipennate: fascicles insert on BOTH sides of tendon (L. bi = two, double) (e.g. rectus femoris)

• Multipennate: many feather-like arrangements all inserting on a single tendon (L. multi = many) (e.g. deltoid, origin: lateral third of clavicle, acromion & spine of scapula)

Muscle attachments to origins & insertions by connective tissue

• Direct or fleshy attachments: connective tissue fibers are short so fascicles appear to attach to bone

• Indirect attachments: tendon: form long connective fibers form cord-like structure or aponeurosis if they form flat

Example(s) where tendons meet bones (forms bone markings)

Tubercles, trochanters, crests, tuberosities