anatomy

Skeletal and Muscular System

8-18-2020

Desuo Wang, PhD

Thinking questions to discuss

Haversian system is present in which of type of bone? Describe the role of osteoblast and osteoclast in bone metabolism

Why Ca is an important nutrient for bone growth

Which hormones are involved in bone growth

Define muscle tone and explain its importance

Define muscle sense and explain its importance

Describe the neuromuscular junction and state the function of each part

Learning Objectives

 Name the components of skeletal system

 Describe the Haversian system

 Distinguish the compact bone from the spongy bone

Describe the role of osteoblast and osteoclast in bone metabolism

 Name the nutrients necessary for bone growth

 Name the hormones involved in bone growth

Name the parts of a synovial joint, and explain their functions

 Define ligament, synovial membrane, synovial fluid

 Name the bones of human skeleton (diagrams)

 Name the landmark structures of skeleton (diagrams)

 Explain how joints are classified. For each type, give an example, and describe the movement possible

The Skeletal System

Skeletal system: bones and other structures that make up the joints. The types of tissue (components):

Bone: bone mineral density (BMD)__measures the mineral density (Ca2+) Cartilage: without Ca2+ salt precipation Ligaments: fibrous connective tissue

Therapeutic agents are targeting the bone and fibrous connective tissues.

FUNCTIONS OF THE SKELETON 1. Provides a framework that supports the body; muscles + skeleton = moving machine. 2. Protects internal organs from mechanical injury. 3. Houses the primary hemopoietic (blood-forming) tissue (bone marrow). 4. Provides a storage site for excess calcium.

Bones are living organs that actively contribute to the maintenance of homeostasis of the internal environment of the body.

BONE TISSUE

A. Bone cells (osteocytes)

Their activity regulates the amount of calcium to be

deposited in, or removed from the bone matrix

B. Matrix (collagen+calcium salts):

Collagen fibers (type 1): Releasing Ca2+ into the blood and

depositing Ca2+ from the diet

Calcium salts:

CaCO 3

Ca 3 (PO

4 ) 2

Dynamic Bone Mineralization: hardness and strength

Bone Density: determined by amount of bone cells and mineral precipitation

Osteonectin: link Ca2+ to collagen

Osteopontin

Osteocalcin: binding to hydroxyapatite

aggregate Hydroxyapatite crystals

http://www.mc.vanderbilt.edu/histology/labmanual2002/labsection1/CartilageandBone03.htm

1. Compact bone

Osteons (Haversian systems):

Cylinders of bone matrix with

osteocytes in concentric rings

around central haversian canals

Endosteum

Periosteum

LamellaeTwo types of bone tissue

 Compact

 Spongy

Haversian systems

2. spongy bone: with visible holes, without Haversian system arrangement

The cavities in spongy bone often contain red bone marrow.

Red bone marrow produces blood cells and platelets.

Osteoporosis: loss of bone density in both compact and spongy bones

Lacuna space and Bone cell (osteocyte)

An osteocyte happily sits inside a lacuna

Cell membrane process

Nucleus

Lacuna space

Canaliculi

1. Osteoblast: make bone

Bone cells (osteocytes)

Osteoblast: Make an extracellular matrix (collagen + hydroxyapatite) to form bone HA: a naturally occurring mineral form of calcium apatite [Ca5(PO4)3(OH)]

Osteoblasts

Periosteum

Skeletal muscle

Deep Fascia

From Skin to Bone: Epidermis Dermis Superficial fascia Deep fascia Muscle Deep fascia Periosteum Bone

Resorption: dissolving and reabsorbing the bone matrix and minerals. Acidification (Ca2+, H3PO4, H2CO3, H2O) + Protease

Proteases: cathepsin K/MMP. Osteoclasts secrete cathepsin K Matrix metalloproteinases (MMPs) are zinc-dependent endopeptidases

2. Osteoclast: reabsorb bone

Osteoclast

Factors affecting bone growth and maintenance

1. Heredity: genetic potential to be a “Yao Min” 2. Nutrition:

Calcium, phosphorus Protein Vitamin D (calcium and phosphorus)

3. Hormones: Pro-growth: growth hormone, thyroxine, parathyroid hormone, and insulin Cessation of bone growth: estrogen or testosterone

4. Exercise (stress with weight): confined to bed thinner and fragile bone

Activity: discuss the acidic body condition and bone metabolism, for example, in patient with chronic kidney disease

Embryonic bone development (growth): ossification cartilage and fibrous connective tissue

Fibroblasts osteoblasts (in the third month of fetal development).

Ossification: produce bone matrix by osteoblasts

Center of ossification: radiative growth

Long bone growth: Epiphyseal discs: produce cartilage by chondrocytes Osteoblast: ossify cartilage (calcifying) Diaphysis: elongation Osteoclast: reabsorb bone forming marrow canal

Build and rebuild process: make stronger bone

After birth, the red bone marrow in the long bones is replaced by yellow bone marrow

HORMONES INVOLVED IN BONE GROWTH AND MAINTENANCE

Growth hormone (anterior pituitary gland)

 the rate of mitosis of chondrocytes and osteoblasts the rate of protein synthesis (collagen, cartilage matrix, and enzymes for cartilage and bone formation)

Thyroxine (thyroid gland)  the rate of protein synthesis  energy production

Insulin (pancreas)  energy production from glucose

Parathyroid hormone (parathyroid glands)

 the reabsorption of calcium from bones to the blood (raises blood calcium level)  the absorption of calcium by the small intestine and kidneys (to the blood)

Calcitonin (thyroid gland)  the resorption of calcium from bones (lowers blood calcium level)

Estrogen (ovaries) closure of the epiphyses of long bones (growth stops)

Testosterone (testes) calcium in bones to maintain a stronger bone matrix

Examples of pharmacy related skeletal problems aplasia osteoporosis hemopoietic inhibition arthritis bone cancer

Examples of anatomy test question:

Red bone marrow is located in: a. compact bone b. spongy bone c. periosteum d. epiphysis

Where can you find yellow bone marrow? a. short bone b. long bone c. flat bone d. irregular bone

CLASSIFICATION OF BONES: based on the shapes

1. Long bones: the bones of the arms, legs, fingers, and toes. Diaphysis (Shaft. Marrow canal) Epiphyses (ends) Red bone marrow/yellow bone marrow (adipose tissue)

2. Short bones: the bones of the wrists and ankles 3. Flat bones: the ribs, shoulder blades, hip bones, and cranial bones (red bone marrow). 4. Irregular bones: the vertebrae and facial bones.

Body Bones

Activity: Types of bone cells vs Types of bone tissues vs Types of bones

Anatomic Terms of Bone Landmarks

Foramen: a hole or opening

Fossa: a depression

Crest: a ridge or edge

Meatus: a tunnel-like cavity

Process: a projection

Facet: a flat projection

Condyle: a rounded smooth projection

Plate: a flat projection

Tubercle: a round projection

Two divisions:

1. Axial skeleton: Skull Vertebral column Rib cage

2. Appendicular skeleton: Arms and legs Shoulder and pelvic girdles

The human skeleton

Example question:

Axial skeleton includes following bones except: a. skull b. vertebral column c. shoulder girdles d. rib cage

SKULL: 8 cranial bones and 14 facial bones three middle ear bones in each side hyoid bone

Lateral view of the human skull

Skull bones and anatomic landmarks

Axial skeleton

Skull__ Anterior view

Cranial bones: frontal, parietal (2), temporal (2), occipital, sphenoid, ethmoid Forms the braincase and the orbits (sockets) for the eyes.

Temporal bone External auditory meatus (ear canal)

Middle ear cavity (middle ear bones) Inner ear labyrinth

Inner ear labyrinth is located in which of following cranial bones?

Occipital bone

Foramen magnum (separate spinal cord from brain) Condyles (rounded projections): articulate with the atlas (first vertebra)

Skull __ Inferior view

Occipital

Foramen magnum

Occipital Condyles

Sella Turcica

Sella Turcica

Olfactory foramina

Cribriform plate

Sphenoid bone 1. wings 2. body

3. Sella turcica pituitary gland

Ethmoid bone 1. Crista galli (a vertical projection)

("rooster's comb") that anchors the cranial meninges.

2. Forms the roof of the nasal cavities and the upper part of the nasal septum.

3. Cribriform plate

4. Offactory foramina transmit offactory nerves

Pituitary gland

Skull __ Superior view

14 Facial bones: Mandible (1): movable, a condyloid joint (Temporomandibular Joint , TMJ) Maxillae (2-3): form the anterior portion of the hard palate (roof of the mouth). Nasal bones (4-5): bone part/cartilage part of the nose Lacrimal bones (6-7): medial side of each orbit;

Lacrimal canal contains the lacrimal sac, a passageway for tears. Lacrimal apparatus: gland, gland ducts, punctum, canal, sac, nasolacrimal duct

Therapeutic Agent in Eye Drops

Mental Foramen

Leads downward into the inferior meatus of the nasal cavity.

Lacrimal canal

Zygomatic bones (8-9): cheek bone

Palatine bones (10-11): posterior portion of the hard palate

Vomer (12): plow-shaped, forms the lower part of the nasal septum

Conchae (13-14): from the sides of the nasal cavities

Curling downward to increase the surface area of the nasal mucosa (warm up air)

14 Facial bones:

Paranasal sinuses: decrease the weight of the skull; resonance of the voice Cavities located in the maxillae, frontal, sphenoid, and ethmoid bones.

opening into the nasal cavities lined with ciliated epithelium continuous with the mucosa of the nasal cavities

Sinusitis/congestion

Activity: Name the paranasal sinuses and relate them to drug delivery

Mastoid sinus: Air cavity in the mastoid process of the temporal bone

opens into the middle ear Middle ear infections may cause mastoiditis

Middle ear and Auditory bones (inside the middle ear cavities): Malleus, incus, and stapes Transmitting vibrations from the eardrum to the receptors in the inner ear.

Eustachian tubes: a small tubes

that run between middle

ears and the upper throat

Pressure balance Middle ear infection

Infant and fetal skulls

Fontanels Less protective

BONES OF THE SKULL__IMPORTANT PARTS

Bone Part Description

Frontal · Frontal sinus · Air cavity that opens into nasal cavity

· Coronal suture · Joint between frontal and parietal bones

Parietal (2) · Sagittal suture · Joint between the 2 parietal bones

Temporal (2) · Squamosal suture · Joint between temporal and parietal bone

· External auditory meatus · The tunnel-like ear canal

· Mastoid process · Oval projection behind the ear canal

· Mastoid sinus · Air cavity that opens into middle ear

· Mandibular fossa · Oval depression anterior to the ear canal; articulates with mandible

· Zygomatic process · Anterior projection that articulates with the zygomatic bone

Occipital · Foramen magnum · Large opening for the spinal cord

· Condyles · Oval projections on either side of the foramen magnum; articulate with the atlas

· Lambdoidal suture · Joint between occipital and parietal bones

Sphenoid · Greater wing · Flat, lateral portion between the frontal and temporal bones

· Sella turcica · Central depression that encloses the pituitary gland

· Sphenoid sinus · Air cavity that opens into nasal cavity

Ethmoid · Ethmoid sinus · Air cavity that opens into nasal cavity

· Crista galli · Superior projection for attachment of meninges

· Cribriform plate and olfactory foramina

· On either side of base of crista galli; olfactory nerves pass through foramina

· Perpendicular plate · Upper part of nasal septum

· Conchae (4 are part of ethmoid; 2 inferior are separate bones)

· Shelf-like projections into nasal cavities that increase surface area of nasal mucosa

BONES OF THE SKULL__IMPORTANT PARTS

Bone Part Description

Mandible Body U-shaped portion with lower teeth

Condyles Oval projections that articulate with the temporal bones

Sockets Conical depressions that hold roots of lower teeth

Maxilla (2) Maxillary sinus Air cavity that opens into nasal cavity

Palatine process Projection that forms anterior part of hard palate

Sockets Conical depressions that hold roots of upper teeth

Nasal (2) __ Form the bridge of the nose

Lacrimal (2) Lacrimal canal Opening for nasolacrimal duct to take tears to nasal cavity

Zygomatic (2) __ Form point of cheek; articulate with frontal, temporal, and maxillae

Palatine (2) __ Form the posterior part of hard palate

Vomer __ Lower part of nasal septum

VERTEBRAL COLUMN (spinal column or backbone)

Components: 7 cervical vertebrae 12 thoracic 5 lumbar 5 sacral bones fused into 1 sacrum 1 coccyx (4 to 5 small coccygeal vertebrae fused together)

Vertebral canal: a continuous tunnel (lined with the meninges)

Cervical vertebrae Atlas ( 1st vertebra) articulates with

1. occipital condyles to support the skull 2. odontoid process of the axis (2nd vertebra) and forms a pivot joint 3. joints (next slide)

Thoracic vertebrae: articulate with the ribs (part of the rib cage) Lumbar vertebrae: the largest and strongest bones of the spine; low back pain Sacrum: sacroiliac joints. Coccyx: remnant of tail vertebrae

Herniated disc or ruptured disc

Inter-vertebral disc: a tough outer covering and a soft center (nucleus pulposus)

Extreme pressure on a disc may rupture the outer layer and force the nucleus pulposus out posteriorly, where it puts pressure on a spinal nerve.

Low back pain

Protection: heart, lungs, liver, spleen

Flexibility: the ribs are pulled upward

and outward by the external

intercostal muscles, enlarging the

chest cavity and contributing to

inhalation.

Sternum: manubrium

body

xiphoid process.

True ribs (1-7): articulate with the

sternum by costal cartilages.

False ribs (8-10): their cartilages join

the 7th rib cartilage.

Floating ribs (11-12): do not

articulate with the sternum at all.

RIB CAGE: 12 pairs of ribs + sternum (breastbone)

Acromion

Humerial Carpals: eight small bones in the wrist

Gliding joints between them permit a sliding movement.

The thumb is more movable than the fingers because of its carpometacarpal joint (a saddle joint), which enables the thumb to cross over the palm, and permits gripping.

Phalanges are the long bones. Between phalanges are hinge joints, which permit movement in one plane.

Table 6-3. BONES OF THE SHOULDER AND ARM¾IMPORTANT PARTS

Bone Part Description

Scapula · Glenoid fossa · Spine · Acromion process

· Depression that articulates with humerus · Long, posterior process for muscle attachment · Articulates with clavicle

Clavicle · Acromial end · Sternal end

· Articulates with scapula · Articulates with manubrium of sternum

Humerus

· Head · Deltoid tubercle · Olecranon fossa · Capitulum · Trochlea

· Round process that articulates with scapula · Round process for the deltoid muscle · Posterior, oval depression for the olecranon process · Round process superior to radius · Concave surface that articulates with ulna

Radius · Head · Articulates with the humerus and ulna

Ulna · Olecranon process · Semilunar notch

· Fits into olecranon fossa of humerus · "Half-moon" depression that articulates with the trochlea of humerus

Carpals (8) · Scaphoid · Lunate · Proximal row

· Triquetrum · Pisiform

· Trapezium · Trapezoid · Distal row

· Capitate · Hamate

THE HIP bones (Pelvic Girdle) The pelvic girdle (or pelvic bone) consists of the two hip bones (coxae or innominate bones), which articulate with the axial skeleton at the sacrum.

Each hip bone has three major parts: the ilium, ischium, and pubis.

Pubic symphysis : pubic bones articulate with one another

Acetabulum: the socket in the hip bone that forms a ball-and-socket joint with the femur.

The wider female pubic angle is an adaptation for childbirth, making the pelvic outlet larger.

Femur: the long bone of the thigh. 1. the greater and lesser trochanters, large

projections that are anchors for muscles. 2. Forms a hinge joint (knee) with the tibia of

the lower leg. 3. forms a ball-and-socket joint 4. condyles

Patella (kneecap): enclosed in the tendon of the quadriceps femoris

The Leg

Tibia: the weight-bearing bone of the lower leg. 1. tibial tuberosity 2. medial malleolus: inner ankle bone

Fibula: is not part of the knee joint. 1. lateral malleolus : outer ankle bone

Tarsals: the seven bones in the ankle. The largest is the calcaneus, or heel bone; the talus transmits weight between the calcaneus and the tibia.

Metatarsals: long bones of feet Phalanges: form hinge joints with each other.

BONES OF THE HIP AND LEG--IMPORTANT PARTS

Bone Part Description

Pelvic (2 hip bones)

· Ilium · Iliac crest · Posterior superior iliac spine · Ischium · Pubis · Pubic symphysis · Acetabulum

· Flared, upper portion · Upper edge of ilium · Posterior continuation of iliac crest · Lower, posterior portion · Anterior, medial portion · Joint between the 2 pubic bones · Deep depression that articulates with femur

Femur

· Head · Neck · Greater trochanter · Lesser trochanter · Condyles

· Round process that articulates with hip bone · Constricted portion distal to head · Large lateral process for muscle attachment · Medial process for muscle attachment · Rounded processes that articulate with tibia

Tibia

· Condyles · Tibial tuberosity · Anterior crest · Medial malleolus

· Articulate with the femur · Round process for the patellar ligament · Vertical ridge · Distal process; medial "ankle bone"

Fibula · Head · Lateral malleolus

· Articulates with tibia · Distal process; lateral "ankle bone"

Tarsals (7) · Calcaneus · Talus

· Heel bone · Articulates with calcaneus and tibia

· Cuboid, navicular --

· Cuneiform: 1st, 2nd, 3rd --

JOINTS (ARTICULATIONS): are where two bones meet, or articulate. Arthritis:

TYPES OF JOINTS (based on the amount of movement possible)

Category Type and Description Examples

Synarthrosis (immovable)

Suture-fibrous connective tissue between bone surfaces

· Between cranial bones; between facial bones

Amphiarthrosis (slightly movable)

Symphysis-disc of fibrous cartilage between bones

· Between vertebrae; between pubic bones

Diarthrosis (freely movable)

Ball and socket-movement in all planes

· Scapula and humerus; pelvic bone and femur

Hinge-movement in one plane · Humerus and ulna; femur and tibia; between phalanges

Condyloid-movement in one plane with some lateral movement

· Temporal bone and mandible

Pivot-rotation · Atlas and axis; radius and ulna

Gliding-side-to-side movement · Between carpals

Saddle-movement in several planes · Carpometacarpal of thumb

1. Articular cartilage (a smooth surface)

2. Capsule (fibrous connective tissue) encloses the joint in a strong sheath.

3. Synovial membrane (Lining the joint capsule) secretes synovial fluid into the joint cavity.

4. Synovial fluid is thick and slippery and prevents friction as the bones move and reduces direct compression to the bones.

Bursae small sacs of synovial fluid between the joint and the tendons. bursitis.

SYNOVIAL JOINTS: All diarthroses, or freely movable joints.

Between two bones

Articular cartilage

Tendons

Ligaments Periosteum (cut to the bone)

Relationship between: tendon, ligament, and periosteum

Tendons and Ligaments of Joints

LEARNING OBJECTIVES

 Describe muscle structure from molecular level to whole muscle

 Define muscle tone and explain its importance

 Explain the difference between isotonic and isometric contraction

 Define muscle sense and explain its importance

 Describe the neuromuscular junction and state the function of each part

 Describe the structure of a sarcomere

 Name the major muscles of the body and describe their function

The Muscular System

The muscular system (Skeletal muscles)

Made of muscle cells (muscle fibers) + Tendons Attached to the bones of the joints (except tongue, some facial muscles) Specialized for contraction

Movement + heat

How are muscles anchored to bones?

Tendon (Aponeurosis: a flat tendon) Muscle (deep) fascia Periosteum

Blood vessels Nerve Lymphatic duct

Interstitial space

Membranous structures Deep fascia (muscle) Epimysium (multiple fascicles) Perimysium (between fascicle) Endomysium (fascicle) Sarcolemma (cell, muscle fiber) Sarcoplasmic reticulum (sub-cellular; around sarcomere)

Contractile structures Muscle Fascicle Motor unit Muscle fiber Sarcomere (myofibril) Myofilaments (the structural units of a myofibril: actin/myosin Cross bridges (sub-molecular)

Membranous and contractile structures of skeletal muscles

http://coffeeblackandcigarettes.wordpress.com/ 2007/02/22/les-muscles/

A

B

C C

D E

Pollicis muscle

A. Muscle level B. Bundle of muscle fibers C. Single muscle cell D. Sarcomere E. Molecular level

MUSCLE STRUCTURE

Which band shortens during muscle contraction?

ROLE OF THE BRAIN Motor neurons (in cerebrum and spinal cord) Motor nerves Electro-chemical nerve impulses Muscle contraction

Coordination: Some muscles contract Others relax Coordination: regulated by brain and cerebellum

Ballet Dancing or Gymnastics

Coordinated movement vs Reflex

Oops!

MUSCLE TONE: A state of slight contraction of skeletal muscles A few of the muscle fibers in that muscle alternatively contract. Muscle tone, is also regulated by the cerebellum.

The heat generated by normal muscle tone is approximately 25% of the total body heat at rest. Exercise increases heat production. Shivering thermogenesis (involuntary!) Malignant hyperthermia

When I am sleepy

When I am too cold

Types of Muscle Contraction

Isotonic contraction : bring about movement concentric contraction: shortening eccentric contraction: lengthening

Isometric contraction: contraction without movement increase muscle tone increase muscle strength

Isotonic contraction Isometric contraction

1000 lb

MUSCLE SENSE (proprioception): where the muscles is (spatial position) what the muscle is doing (contractile status or muscle activity) without consciously looking at them

Stretch receptors (proprioceptors or muscle spindles). sensory receptors (detecting change in the length) sending sensory impulses to the brain

position strength length resistance

CNS: integrating the sense into a controlled movement or a subconscious reflex Cerebrum: conscious muscle sense Cerebellum: unconscious muscle sense

Extrafusal muscle fibers

-Motor fibers Muscle spindle

Intrafusal

ENERGY SOURCES FOR MUSCLE CONTRACTION ATP Creatine phosphate   ATP Glycogen  Glucose (w/wo O2)  ATP Fatty acid oxidation O2  ATP

1

2

3

4

5

6

Ca2+

Movements of upper arm at the shoulder: Abducting the arm--by the deltoid Adducting the arm--by the pectoralis major and latissimus dorsi Flexion of the arm –by the pectoralis major Extension of the arm --by latissimus dorsi Rotating the arm– by pectoralis, subscapularis, and teres

http://ajs.sagepub.com/content/30/6/886/F4.expansion

Range-of-motion (or ROM): distance and direction a joint can move to its full potential. a normal ROM (degrees) measured with a goniometer (measures angles from axis of the joint).

Limited Range of Motion: osteoarthritis, rheumatoid arthritis, or gout).

Presynaptic components Motor neuron endings Sarcolemma membrane Synaptic cleft Synaptic vesicles Neurotransmitter Acetylcholine (ACh)

Postsynaptic components ACh receptors Cholinesterase

http://www.biologycorner.com/anatomy/muscles/neuromuscular_junction.jpg

Neuromuscular junction

education.vetmed.vt.edu/.../Labs/Lab10/lab10.htm

Motor neuron axon Motor end plates Muscle spindle Neuromuscular Junction

Nerve control of muscle contraction

Muscle spindle 1.Contractile 2.Non-contractile 3.Ia sensory fiber 4. Motor fiber

1

2

34

Intrafusal

muscle fibers

Extrafusal muscle fibers

-Motor fibers

Extrafusal

muscle fibers

-Motor fibers Muscle spindle

Neuromuscular

junction:

Intrafusal

The contracting units of muscle fiber are ______ (sarcomeres)

Myosin: in the center of the sarcomere Actin: attached to the Z lines (ends or boundaries of sarcomere) Titin: anchoring myosin to Z lines.

Contractile proteins: actin and myosin Regulatory proteins: troponin and tropomyosin Anchoring protein: Titin

Sarcoplasmic reticulum: a reservoir for calcium ions (Ca2+)

Muscle contration: Nerve impulse  release of acetylcholine  generates electrical changes at the sarcolemma of the muscle fiber  initiate a sequence of events called the sliding filament mechanism  muscle contraction

SARCOLEMMA__POLARIZATION

1. Polarized resting potential: outside positive inside negative

Sodium ions (Na+) are more abundant outside the cell, and potassium ions (K+) and negative ions are more abundant inside (The Na+ and K+ gradients are maintained by the Na+-K+ ATPase activity)

2. Depolarization: Na+ influx  action potential T tubules Ca2+ influx

3. Repolarization : K+ efflux Na+/K+ ATPase (pumping)

Muscle Cell Excitation

Resting Potential

Polarization Sarcolemma has a resting membrane potential of -90 mV Na+-K+ ATPase (pump) maintains the Na+/K+ ionic gradients.

Action Potential

Depolarization

ACh permeability to Na+ ions Influx of Na+ reverses the charges on the sarcolemma

In activation of Na+ channels and cholinesterase inactivates Ach.

Repolarization permeability to K+ ions and K+ efflux through its channels Ready for responding to next nerve impulse

CONTRACTION__THE SLIDING FILAMENT MECHANISM

Excitation-contraction coupling: a nerve impulse causes depolarization of a muscle fiber (excitation), and this electrical change enables the myosin filaments to pull the actin filaments toward the center of the sarcomere, making the sarcomere shorter (contraction).

Step-by-step coupling:

1. Nerve impulse  ACh release  receptor activation 2. Activation of Na+ channels  Na+ influx  depolarization

3. T tubules depolarization  Ca2+ enter  release of Ca2+ from sarcoplasmic reticulum

4. Ca2+ bonds to the troponin-tropomyosin complex and remove the inhibition to actin

5. Myosin uses ATP, bridges with actin and pull them toward the center of the sarcomere

6. The sarcolemma repolarizes: K+ efflux and ATP pumps return Na+ outside and K+inside. 7. Cholinesterase in the sarcolemma inactivates ACh

8. Relaxation

TETANUS AND BOTULISM

Tetanus: inability of muscles to relax (spasm) tetanus bacteria  neurotoxin  stops the affected neurons from releasing the

GABA (gamma-aminobutyric acid) and glycine  tetanic spasm

Lock-jaw: difficulty opening the mouth because of spasms of the masseter muscles.

Spasm of the respiratory muscles  death

Botulism: botulism bacteria  neurotoxin   release of ACh  paralysis.

Strychnine poisoning:

Myasthenia gravis: an autoimmune disorder characterized by lossing ACh receptors (extreme muscle fatigue)

Intramuscular injections (IM)

rapid absorption bypass the first-pass metabolism

Common sites Gluteus medius Vastus lateralis

Deltoid

Avoiding the nerves and vessels!

sciatic nerve radial nerve

Intramuscular injections

MAJOR MUSCLES OF THE BODY

1. Location and action 2. Origins and insertions 3. Joints involved

How muscles are named?

Location Abdominis: an abdominal muscle, Femoris: a thigh muscle, Brachii: a muscle of the upper arm, Oculi: an eye muscle,

Size Longus Maximus

Function Flexor Extensor

ACTIONS OF MUSCLES

Action Definition

Flexion To decrease the angle of a joint

Extension To increase the angle of a joint

Adduction To move closer to the midline

Abduction To move away from the midline

Pronation To turn the palm down

Supination To turn the palm up

Dorsiflexion To elevate the foot

Plantar flexion To lower the foot (point the toes)

Rotation To move a bone around its longitudinal axis

Most are grouped in pairs of antagonistic functions.

MUSCLES OF THE HEAD AND NECK: moving the head/neck, facial expression, and chewing

Sternocleidomastoids (flexion): turn and bend head Muscles for smiling, frowning or raising eyebrows Masseter: chewing

MUSCLES OF THE TRUNK

E.g., Rectus abdominis (flexion) Sacrospinalis group (extension)

Trapezius: raise the shoulder and extend the head. Pectoralis major: pulls the arm across the chest Latissimus dorsi: pulls the arm downward and behind

the back (extension and adduction).

Respiratory Muscles Intercostal muscles between the ribs Diaphragm: between thoracic and abdominal cavities

MUSCLES OF THE SHOULDER AND ARM

Triangular deltoid: abduction and flexion and extension of the humerus.

Biceps brachii and triceps brachii:

The muscles that form the bulk of the forearm are the flexors and extensors of the hand and fingers.

MUSCLES OF THE HIP AND LEG: Move the thigh Pelvic bone and femur

Gluteus maximus (extension); Gluteus medius (abduction); Iliopsoas (flexion). Quadriceps group (anteriorly) Hamstring group (posteriorly)

Movement of the foot depends on lower leg muscles (gastrocnemius (dorsiflexion or flexion) and the tibialis anterior (plantar flexion or extension).

MUSCLES OF THE HEAD AND NECK

Muscle Function Origin Insertion

Frontalis Raises eyebrows, wrinkles skin of forehead

epicranial aponeurosis skin above supraorbital margin

Orbicularis oculi Closes eye medial side of orbit encircles eye

Orbicularis oris Puckers lips encircles mouth skin at corners of mouth

Masseter Closes jaw maxilla and zygomatic mandible

Buccinator Pulls corners of mouth laterally

maxilla and mandible orbicularis oris

Sternocleidomastoid Turns head to opposite side (both_flex head and neck)

sternum and clavicle temporal bone (mastoid process)

Semispinalis capitis (a deep muscle)

Turns head to same side (both¾extend head and neck)

7th cervical and first 6 thoracic vertebrae

occipital bone

Splenius capitis Turns head to same side (both_extend head)

7th cervical and first 4 thoracic vertebrae

occipital bone

MUSCLES OF THE TRUNK

Muscle Function Origin Insertion

Trapezius Raises, lowers, and adducts shoulders

occipital bone and all thoracic vertebrae

spine of scapula and clavicle

External intercostals

Pull ribs up and out (inhalation)

superior rib inferior rib

Internal intercostals

Pull ribs down and in (forced exhalation)

inferior rib superior rib

Diaphragm Flattens (down) to enlarge chest cavity for inhalation

last 6 costal cartilages and lumbar vertebrae

central tendon

Rectus abdominis

Flexes vertebral column, compresses abdomen

pubic bones 5th-7th costal cartilages and xiphoid process

External oblique Rotates and flexes vertebral column, compresses abdomen

lower 8 ribs iliac crest and linea alba

Sacrospinalis group (deep muscles)

Extends vertebral column ilium, lumbar, and some thoracic vertebrae

ribs, cervical, and thoracic vertebrae

MUSCLES OF THE SHOULDER AND ARM

Muscle Function Origin Insertion

Deltoid Abducts the humerus scapula and clavicle humerus

Pectoralis major Flexes and adducts the humerus

clavicle, sternum, 2nd-6th costal cartilages

humerus

Latissimus dorsi Extends and adducts the humerus

last 6 thoracic vertebrae, all lumbar vertebrae, sacrum, iliac crest

humerus

Teres major Extends and adducts the humerus

scapula humerus

Triceps brachii Extends the forearm humerus and scapula ulna

Biceps brachii Flexes the forearm scapula radius

Brachioradialis Flexes the forearm humerus radius

MUSCLES OF THE HIP AND LEG

Muscle Function Origin Insertion

Iliopsoas Flexes femur ilium, lumbar V. femur

Gluteus maximus Extends femur iliac crest, sac/cocy femur

Gluteus medius Abducts femur ilium femur

Quadriceps femoris group: Rectus femoris Vastus lat. Med. Intermed

Flexes femur and extends lower leg

ilium and femur tibia

Hamstring group: Biceps femoris; semimembranosus Semitendinosus

Extends femur and flexes lower leg

ischium tibia and fibula

Adductor group Adducts femur ischium and pubis femur

Sartorius Flexes femur/ lower leg ilium tibia

Gastrocnemius Plantar flexes foot femur calcaneus (Achilles tendon)

Soleus Plantar flexes foot tibia and fibula calcaneus (Achilles tendon)

Tibialis anterior Dorsiflexes foot tibia metatarsals

MUSCLES OF THE PELVIC FLOOR

Muscle Function Origin Insertion

Levator ani

Supports pelvic organs, especially during defecation, urination, coughing, and forced exhalation; constricts anus, urethra, and vagina

pubis and ischium

coccyx, anal canal, urethra

Coccygeus

Supports pelvic organs, especially during defecation, urination, coughing, and forced exhalation

ischium coccyx and sacrum

Ischiocavernosus Erection of clitoris in female, penis in male

ischium and pubis

clitoris or penis

Bulbospongiosus Assists urination; erection in female; erection and ejaculation in male

central tendon of perineum

fasciae, pubic arch, clitoris, or penis

Transverse perineus (superficial and deep)

Assists urination in female; urination and ejaculation in male

ischium central tendon of perineum

External anal sphincter

Closes anus anococcygeal ligament

central tendon of perineum

Muscles in the pelvic cavity: forming the pelvic floor and support the pelvic organs and assist with urination and defecation.

After the class you should be able to

Describe the structure of the Haversian system and distinguish the compact bone from the spongy bone

Describe the role of osteoblast and osteoclast in osteoporosis

Explain the roles of nutrients and hormones in bone metabolism and growth

Define ligament, synovial membrane, synovial fluid

Describe muscle structure from molecular level to whole muscle

Define muscle tone and explain its importance and relate it to muscle sense and explain its importance

Describe the neuromuscular junction and state the function of each part

Describe the structure of a sarcomere