Unit 3 Learning Objectives Flashcards
1
Q
Describe the axial skeleton and list the general bone structures contained within it
A
The axial skeleton has 80 named bones, and includes structures such as the skull, vertebrae, sternum, ribs, sacrum, and hyoid.
2
Q
Describe the appendicular skeleton and list the general bone structures contained within it
A
The appendicular skeleton has 126 named bones, and includes structures such as the pectoral and pelvic girdles and upper and lower extremities (limbs).
3
Q
Name the cranial bones and describe their locations
A
There are 8 cranial bones; two parietal, two temporal, frontal, occipital, sphenoid, and ethmoid.
The parietal bones are located at the apex of the head.
The frontal bone is located at the front of the head.
The temporal bones are located on the sides of the head (this is where the ears are located)
The sphenoid bone makes up the back of the eye socket
The ethmoid bone makes up the medial part of the eye socket.
4
Q
Name the facial bones and describe their locations
A
There are 14 facial bones; two nasal, 2 maxilla, 2 lacrimal, 2 zygomatic, 2 inferior nasal concha, 2 palatine, vomer, and mandible.
The nasal bones are located towards the top of the nose.
The two maxillary bones are located superior to both the upper and lower teeth and inferior to the nose
The two zygomatic bones are located on either side of the face (often referred to as ‘cheekbones’)
The two lacrimal bones are located on the medial side of the eye sockets (superficial to the ethmoid bone).
The two inferior nasal concha are located on both lateral sides of the vomer.
The vomer makes up the middle of the nose and separates the left nostril from the right.
The mandible makes up the chin and lower jaw (inferior to the maxillary bone and teeth).
5
Q
Describe the hyoid bone
A
This bone is located deep and inferior to the mandible, and it does not articulate with any other bones.
6
Q
Describe the naming conventions of bone markings
A
- As a general rule, anything named as a process, tubercle, tuberosity, trochanter, condyle, or crest are projections of bone and are generally used as attachment sites for muscles or ligaments.
- Anything named as a foramen is a hole typically used for blood vessels or nerves.
- Anything named as a fissure is a slit-like narrow opening.
- Anything named as a notch is an indentation or large groove in a bone, and anything named a fossa is a shallow depression.
7
Q
Describe the features/markings of the occipital bone (2)
A
- The occipital bone contains the foramen magnum, which is a hole in the occipital bone where the brainstem enters.
- The occipital condyles are round kidney bean shapes around the foramen magnum, which is where the skull articulates with vertebrae (this is what gives the us the ability to nod our heads vertically)
8
Q
Describe the features/markings of the temporal bone (4)
A
- The temporal bone contains the external acoustic meatus, which is the hole of the ear canal.
- The mastoid process is a rather large bony projection that is located behind the ear.
- The styloid process is a small bony projection that serves as an anchor point for muscles associated with the tongue and larynx.
- The mandibular fossa is a shallow depression located just slightly anterior to the styloid process.
9
Q
Describe the features/markings of the sphenoid bone (5)
A
- The majority of the sphenoid bone is made up of the greater and lesser wings (the lesser wing is anterior to the greater wing).
- The sella turcica is where the brain sits.
- The superior orbital fissure is a spike/triangular shaped hole, and allows certain nerves to enter the orbit.
- The optic canal lets the optic nerve into the orbit.
10
Q
Describe the features/markings of the ethmoid bone (3)
A
- The ethmoid bone has cribriform plates, the holes of which are what allow nerves entry to the nasal cavity.
- The olfactory foramina lets bundles of nerve fibers of the olfactory nerve enter the nasal cavity. -The meninges anchor to the crista galli.
11
Q
List the bones that contain the paranasal sinuses.
A
The frontal, sphenoid, ethmoid, and maxillary bones.
12
Q
Define and describe the purposes of fontanelles in a newborn skull
A
Fontanelles in the newborn skull are dense connective tissue membrane-filled spaces
(soft spots); they are unossified at birth but close early in a child’s life. They have two purposes: to allow the fetal skull to pass through the birth canal, and to allow rapid growth of the brain during infancy.
13
Q
List the most common fontanelles found in the newborn skull
A
The most common fontanelles are the sphenoidal (aka anterolateral fontanel), the mastoid (aka posterolateral fontanel), the anterior fontanel, and the posterior fontanel.
14
Q
Describe the general features of the vertebral column
A
The vertebral column typically consists of 7 cervical vertebrae (C1 is the atlas and C2 is the axis), 12 thoracic vertebrae, 5 lumbar vertebrae, sacrum (5, fused), and coccyx (3-5, fused).
15
Q
Describe the general features of vertebrae
A
Typical vertebra consist of a body, vertebral foramen (where the spinal cord goes), and a spinous process (excluding the atlas).
16
Q
Describe the general differentiating features of cervical, thoracic, and lumbar vertebrae.
A
The cervical vertebra have a transverse foramen to let the vertebral arteries travel up to the head and neck.
The thoracic vertebrae typically each attach to a pair of ribs.
The lumbar vertebrae typically have very large bodies.
17
Q
Describe the structure of the intervertebral discs and their relationship to the vertebrae.
A
Intervertebral discs are made of fibrocartilage with a pulpy center and are located between each vertebrae, and their purpose is to absorb vertical shock and allow for the vertebral column to move.
18
Q
Describe herniated discs
A
If the nucleus pulposus of an intervertebral disc herniates, it puts pressure on the nerves and causes pain.
19
Q
Describe the primary normal curvatures of the vertebral column.
A
Primary curvatures: thoracic and sacral curves, which form during fetal development
20
Q
Describe the secondary normal curvatures of the vertebral column
A
Secondary curvatures: cervical and lumbar curves; the cervical curve forms when infant raises head at 4 months, and the lumbar curve forms when an infant sits up & begins to walk.
21
Q
Describe how the shape of the spine changes during the first 3 years of life.
A
The spine has a C-shaped curve at birth (convex) and is S-shaped past the age of 3 years.
22
Q
Describe the three abnormal curvatures of the vertebral column.
A
Kyphosis (hunchback): exaggerated thoracic curvature, usually from osteoporosis, osteomalacia, spinal tuberculosis, or weightlifting and/or wrestling from a young age.
Lordosis (swayback): exaggerated lumbar curvature
Scoliosis: lateral bending of the spinal column; the most common abnormal curve, and is often seen in adolescent girls.
23
Q
Describe the anatomy of the sternum and ribs and how the ribs articulate with the thoracic vertebrae.
A
Ribs 1-7 are true ribs (their cartilage directly connects to the sternum) 8-12 are false ribs (they indirectly connect to the sternum), and ribs 11-12 are floating ribs (they do not connect to the sternum). Each thoracic vertebrae articulates with a pair of ribs.
24
Q
Identify the features of the scapula
A
Scapular spine, acromion process, coracoid process, glenoid cavity, supraspinous fossa, infraspinous fossa, subscapular fossa.
25
Scapula: Describe the scapular spine
The scapular spine is a horizontal line of protruding bone along the posterior side of the scapula.
26
Scapula: Describe the acromion process
The acromion process is a bulbous end found at the lateral side of the scapular spine.
27
Scapula: Describe the coracoid process
The coracoid process is a protrusion similar in appearance to the acromion process, but on the anterior side of the scapula.
28
Scapula: Describe the glenoid cavity
The glenoid cavity is a groove situated between the acromion and coracoid processes.
29
Scapula: Describe the supraspinous fossa
The supraspinous fossa is a shallow indentation superior to the scapular spine on the posterior side.
30
Scapula: Describe the infraspinous fossa
The infraspinous fossa is a shallow indentation inferior to the scapular spine on the posterior side.
31
Scapula: Describe the subscapular fossa
The subscapular fossa is a shallow indentation inferior to the scapular spine on the anterior side.
32
List the proximal and distal features of the humerus
Proximal end: head, surgical neck, anatomical neck, greater tubercle, lesser tubercle, intertubercular groove, deltoid tuberosity
Distal end: olecranon fossa, coronoid fossa, radial fossa, capitulum, trochlea, medial epicondyle, lateral epicondyle.
33
Humerus: Describe the head, surgical neck, and anatomical neck
- The head of the humerus is a the rounded side of the proximal end, and is pointed medially.
- The surgical neck is the thinner area below the anatomical neck of the proximal end of the humerus where the humerus is cut during amputations.
- The anatomical neck is located just inferior to the head of the humerus on the proximal end; it is where the head of the humerus ends.
34
Humerus: Describe the greater tubercle and lesser tubercle
The greater tubercle is a small, rounded projection that is located on the lateral side of the humerus on the proximal end.
The lesser tubercle is a small, rounded projection that is located on the medial side of the humerus on the proximal end.
35
Humerus: Describe the intertubercular groove
The intertubercular groove is located between the greater and less tubercles, and is an indentation in the bone on the proximal end.
36
Humerus: Describe the deltoid tuberosity
The deltoid tuberosity is the only feature of the humerus located on the diaphysis, and is the attachment site for the deltoid muscle.
37
Humerus: Describe the olecranon fossa
The olecranon fossa is a large indentation located on the posterior distal end of the humerus.
38
Humerus: Describe the coronoid fossa and the radial fossa
- The coronoid fossa is a small indentation located on the medial anterior side of the distal end.
- The radial fossa is a small indentation (smaller than the coronoid fossa) located on the lateral anterior side of the distal end.
39
Humerus: Describe the capitulum
The capitulum is a rounded portion of the lateral anterior side of the distal end that articulates with the head of the radius, and is just inferior to the radial fossa.
40
Humerus: Describe the trochlea
The trochlea is a rounded portion of the medial anterior side of the distal end that articulates with the trochlear notch of the ulna, and is just inferior to the coronoid fossa.
41
Humerus: Describe the medial and lateral epicondyles
- The medial epicondyle is a rounded articular projection that the pronator teres and some ligaments attach to, and is located on the medial side of the distal end.
- The lateral epicondyle is a rounded articular projection that ligaments attach to, and is located on the lateral side of the distal end.
42
List the proximal and distal features of the radius
Proximal end: head, neck, radial tuberosity
| Distal end: ulnar notch.
43
Describe the proximal features of the radius
The head is a round, circular part of the radius at the proximal end.
The neck is located just below the head of the radius at the proximal end.
The radial tuberosity is an elevated portion of the radius on the diaphysis located near the proximal end.
44
Radius: Describe the ulnar notch
The ulnar notch is a notch located on the distal end of the radius, and is where the ulna and radius articulate.
45
List the proximal and distal features of the ulna
Proximal end: olecranon process, coronoid process, trochlear notch, radial notch.
Distal end: styloid process.
46
Ulna: Describe the olecranon process
The olecranon process is a large, bony projection located on the posterior side of the ulna on the proximal end.
47
Ulna: Describe the coronoid process
The coronoid process is a large, bony projection located on the anterior side of the ulna on the proximal end; it is barely visible from the posterior view.
48
Ulna: Describe the trochlear notch and the radial notch
The trochlear notch is a large notch on the proximal end of the ulna that articulates with the humerus.
The radial notch is a large notch on the lateral anterior side of the proximal end of the ulna, and articulates with the radius.
49
Ulna: Describe the styloid process
The styloid process is a smaller bony projection on the distal end of the ulna.
50
Carpals: Describe the scaphoid, trapezium, and lunate bones.
- The scaphoid bone is just proximal to the trapezium.
- The trapezium is proximal to the thumb and superior to the scaphoid bone.
- The lunate is located directly lateral to the scaphoid bone, and is inferior to the IV metacarpal.
51
Bones of the hand: Describe the metacarpals and phalanges
- Metacarpals: 5 bones labeled as I, II, III, IV, and V; the I metacarpal is located just inferior to the pollux.
- Phalanges: proximal, middle, and distal in each finger; proximal and distal phalanx in thumb.
52
The _____ is immediately superior to the coccyx
Sacrum
53
List the features of the coxal bone
Acetabulum, ilium (iliac crest, auricular surface, greater sciatic notch), ischium (ischial tuberosity, obturator foramen), and pubis (pubic symphysis).
54
Coxal bone: Describe the acetabulum
The acetabulum is located on either lateral side of the anterior coxal bone, and is where the head of the femur articulates.
55
Coxal bone: Describe the ilium and its features
- The ilium is the biggest and most superior portion of the coxal bone; located on either lateral side on both the posterior and anterior sides of the coxal bone.
- The iliac crest is located mostly on the anterior side of the ilium, and is where the ilium “folds over”
- The auricular surface is the rough surface located on the lateral side of the coxal bone, and is superior to the greater sciatic notch.
- The greater sciatic notch is located just inferior to the auricular surface.
56
Coxal bone: Describe the ischium and its features
- The ischium is located on the lateral side of the coxal bone, and is lateral to the pubis and inferior to the ilium.
- The ischial tuberosity is a rough, elevated area located on the lower anterior lateral side of the coxal bone.
- The obturator foramen is a large hole in the ischium and pubis of the coxal bone that allows nerves and blood vessels to pass through it.
57
Coxal bone: Describe the pubis and its features
- The pubis is located on the medial side of the coxal bone, and is medial to the ischium and inferior to the ilium.
- The pubis symphysis is the most medial feature of the coxal bone, and is where the pubic bones articulate.
58
List the proximal and distal features of the femur
Proximal end: head, neck, greater trochanter, lesser trochanter
Distal end: lateral condyle, medial condyle, lateral epicondyle, medial epicondyle.
59
Femur: Describe the head and neck
- The head of the femur is a round bulbous end located on the proximal end of the femur, and is where it articulates with the acetabulum.
- The neck of the femur is located just below the head on the proximal end.
60
Femur: Describe the greater and lesser trochanters
- The greater trochanter is a large, rounded projection located on the posterior side of the proximal end of the femur, and is superior to the lesser trochanter.
- The lesser trochanter is a large, rounded projection located on the posterior side of the proximal end of the femur, and is inferior to the greater trochanter.
61
Femur: Describe the lateral and medial condyles.
- The lateral condyle is a rounded articular projection located on the lateral distal end of the femur; it is inferior to the lateral epicondyle and visible from both the anterior and posterior views.
- The medial condyle is a rounded articular projection located on the medial distal end of the femur; it is inferior to the medial epicondyle and visible from both the anterior and posterior views.
62
Femur: Describe the lateral and medial epicondyles
- The lateral epicondyle is a rounded projection located on the lateral distal end of the femur; it is superior to the lateral condyle and visible from both the anterior and posterior views.
- The medial epicondyle is a rounded projection located on the medial distal end of the femur; it is superior to the medial condyle and visible from both the anterior and posterior views.
63
List the proximal and distal features of the tibia
Proximal end: articular surface of medial and lateral condyles, anterior border
Distal end: medial malleolus
64
Tibia: Describe the articular surfaces of the lateral and medial condyles
- The articular surface of the medial condyle is located on the medial side of the proximal end of the tibia; it is more visible from the posterior view.
- The articular surface of the lateral condyle is located on the lateral side of the proximal end of the tibia; it is more visible from the posterior view.
65
Tibia: Describe the anterior border
The anterior border is the vertical ridge on the anterior side of the tibia’s diaphysis.
66
Tibia: Describe the medial malleolus
The medial malleolus is located on the medial side of distal end of the tibia, and is a bony hook-shaped process.
67
List and describe the features of the fibula
Fibula: Lateral malleolus
| The lateral malleolus is located on the lateral side of the distal end of the fibula, and is a slightly curved process.
68
Tarsals: Describe the talus and calcaneus
The talus is a large bone that is the most proximal bone of the foot.
The calcaneus is a large bone located distally to the talus.
69
Describe the metatarsals and phalanges
- Metatarsals (5 bones): The metatarsals are numbered I-V, with the metatarsal I located just proximally to the hallux’s phalangeal bones.
- Phalanges (proximal, middle, and distal in each toe; proximal and distal phalanx in hallux)
70
Compare the anatomy of the male and female pelvic girdles and explain the functional significance of the differences.
- Male pelvic girdle: heavier and thicker with larger acetabula closer to each other.
- Female pelvic girdle: wider and shallower, tilted more forward, and adapted to the needs of pregnancy and childbirth, larger pelvic inlet (brim) and outlet for passage of infant’s head.
- These differences are important because the female pelvic girdle needs to be adapted to allow for an infant’s head to pass through it during child birth.
71
Explain what joints are and what functions they serve.
A joint, or articulation, is defined as any point where two bones meet, whether or not the bones are movable at that interface.
72
Name the four major structural categories of joints
- Bony (synostoses)
- Cartilaginous (amphiarthroses)
- Fibrous (synarthroses)
- Synovial (diarthroses)
73
Describe bony (synostoses) joints
Immobile; when the gap between two bones ossifies (becomes one bone). Examples: Left and right mandibular bones in infants, cranial sutures in elderly, attachment of first rib and sternum with old age.
74
Describe cartilaginous (amphiarthroses) joints and list the two kinds
A slightly movable joint; two types are symphyses and syndesmoses
75
Describe fibrous (synarthroses) joints and list the three different kinds
- Type of joint which permits very little or no movement. Bones are bound by collagen fibers that emerge from one bone and penetrate into the other.
- Three kinds of fibrous joints: Sutures, gomphoses, and syndesmoses
76
Describe synovial (diarthrosis) joints
Freely movable joints (has a joint capsule)
77
Describe the three types of fibrous joints and give an example of each.
- Sutures: Immobile or slightly mobile; uses short collagen fibers. Ex: sagittal suture of the skull.
- Gomphoses: Attachment of a tooth to its socket; the tooth is held in place by fibrous periodontal ligament (collagen). This allows the tooth to move a little under the stress of chewing. Ex: teeth.
- Syndesmoses: Two bones are bound by long collagen fibers. Example of a very mobile syndesmosis: interosseus membrane joining radius to ulna (allows supination & pronation). An example of a less mobile syndesmosis: joint between tibia to fibula
78
Describe the two types of cartilaginous joints and give an example of each
1) Synchondrosis: bones joined by hyaline cartilage.
Examples: Epiphyseal plates in children (temporary joints), first rib attachment to sternum (other costal cartilages joined to sternum by synovial joints).
2) Symphysis: two bones joined by fibrocartilage
Examples: Pubic symphysis, bodies of vertebrae joined by intervertebral discs
79
Identify and describe the anatomical components of a typical synovial joint.
1) Articular cartilage (usually 2 or 3 mm thick)
-Absorbs shock and made of hyaline cartilage
2) Joint (articular) cavity
3) Synovial fluid: slippery lubricant in joint cavity
-Rich in albumin and hyaluronic acid
-Gives it a viscous, slippery texture like raw egg whites and nourishes articular cartilage and removes waste
-Makes movement of synovial joints almost friction free
4) Joint (articular) capsule
-Outer fibrous capsule: continuous with periosteum
-Inner, cellular, synovial membrane:
fibroblast-like cells that secrete synovial fluid and macrophages that remove debris from the joint cavity
80
Explain the beneficial effects of exercise on articular cartilage.
- Exercise warms synovial fluid; it becomes less viscous, more easily absorbed by cartilage
- Cartilage then swells; becomes a more effective cushion
- Repetitive compression and decompression of cartilage (during exercise) moves synovial fluid in and out of the cartilage like a sponge.
- Oxygen and nutrients are brought to chondrocytes; wastes are taken away
- Without exercise, cartilage deteriorates more rapidly from inadequate nutrition and waste removal
- A warm-up period before vigorous exercise helps protect cartilage from undue wear and tear
81
Define range of motion (ROM)
Defined as the degrees through which a joint can move. An aspect of joint performance; a physical assessment of a patient’s joint flexibility
82
List and describe the factors that determine range of motion
1) Shape of the articular surfaces
- Elbow: olecranon of ulna fits into olecranon fossa of humerus
2) Strength and tautness of ligaments and joint capsules
- Stretching of ligaments increases range of motion
- Double-jointed means people have very long or slack ligaments.
3) Action of the muscles and tendons
- Nervous system monitors joint position and muscle tone
- Muscle tone: state of tension maintained in resting muscles
83
Describe the primary axes of rotation that a bone can have and relate this to the different movements that are possible.
- Multiaxial joint: shoulder joint has three degrees of freedom or axes of rotation
- --This allows the shoulder to abduct, internally rotate, and flex.
- Monoaxial: 1 degree of freedom
- Biaxial: 2 degrees of rotation
84
Name the six classes of synovial joints
1) Ball-and-socket joints
2) Condylar (ellipsoid) joints
3) Plane (gliding) joints
4) Saddle joints
5) Hinge joints
6) Pivot joints
85
Describe ball-and-socket joints and condylar (ellipsoid) joints
1) Ball-and-socket joints
- Only multiaxial joints in body
- Example: humeroscapular joint
2) Condylar (ellipsoid) joints
- Oval convex surface of one bone fits into a complementary-shaped depression on the other
- Biaxial
- Examples: radiocarpal joint, metacarpophalangeal joints, atlanto-occipital joint
86
Describe plane (gliding) joints and saddle joints
1) Plane (gliding) joints
- Flat articular surfaces, bones slide over each other
- Usually biaxial joints
- Examples: intercarpal; intertarsal; between articular processes of vertebrae
2) Saddle joints
- Both bones have an articular surface that is shaped like a saddle, one concave, the other convex
- Biaxial joints
- Example: trapeziometacarpal (opposable thumb)
87
Describe hinge and pivot joints
1) Hinge joints
- One bone with convex surface fits into a concave depression of another bone
- Monoaxial joints—move freely in one plane
- Examples: elbow, knee, joints within fingers, toes
2) Pivot joints
- A bone spins on its longitudinal axis
- Monoaxial joints
- Examples: atlantoaxial joint (C1 and C2), radioulnar joint at the elbow
88
Describe flexion vs extension, and abduction vs adduction
Flexion: “bending”; decreasing the angle between two bones.
Extension: “straightening”; increasing the angle between two bones
Abduction: moving [a limb] away from the midline
Adduction: moving [a limb] toward the midline
89
Describe protraction vs retraction, and supinate vs pronate
Protraction: pulling the scapula forward
Retraction: pulling the scapula backward
Supinate: turning the palms upward in anatomical position
Pronate: turn the palms downward, not in anatomical position.
90
Identify the major anatomical features of the jaw joint (TMJ)
- Articulation of the condyle of the mandible with the mandibular fossa of the temporal bone
- Combines elements of condylar, hinge, and plane joints
- Synovial cavity of the TMJ is divided into superior and inferior chambers by an articular disc
- Deep yawn or strenuous depression can dislocate the TMJ
- Condyles pop out of fossa and slip forward; relocated by pressing down on molar teeth while pushing the jaw backward
91
Describe TMJ syndrome (occurrence, symptoms, causes, and treatment)
- May affect as many as 75 million Americans
- Signs and symptoms: Clicking sounds in the jaw, imitation of jaw movement; pain radiating from jaw down the neck, shoulders, and back; can cause moderate intermittent facial pain, or severe headaches, vertigo (dizziness), tinnitus (ringing in the ears)
- Caused by: a combination of psychological tension and malocclusion (misalignment of teeth)
- Treatment: Psychological management, physical therapy, analgesic and anti-inflammatory drugs, corrective dental appliances to align teeth properly
92
Identify the major anatomical features of the shoulder joint (glenohumeral/humeroscapular)
- Bones: humerus, scapula
- Most freely mobile joint in body
- Sacrifices stability for freedom of movement
- Glenoid labrum: fibrocartilage ring that deepens glenoid cavity
- Joint stabilized by tendons fused to joint capsule: Biceps brachii tendon and Rotator cuff tendons
- Stabilized in all directions except inferiorly
93
Describe what type of joint the elbow joint is
Combination of a hinge and a pivot joint
94
Describe the hinge joint portion of the elbow joint
Hinge joint includes two articulations:
-Humeroulnar joint: trochlea of the humerus joins trochlear notch of the ulna
-Humeroradial joint: capitulum of humerus meets head of radius
Both articulations enclosed in one joint capsule
95
Describe the pivot joint portion of the elbow joint
- Pivot joint consists of the proximal radioulnar joint
- Head of radius fits into radial notch of ulna
- Held in place by anular ligament encircling radial head
- Allows for pronation and supination
96
Describe the major features of the hip (coxal) joint
- Coxal (hip) joint—head of femur inserts into acetabulum of hip bone
- More stable than shoulder
- Acetabular labrum—horseshoe-shaped ring of fibrocartilage that deepens socket
- Dislocations are rare
97
Describe the general structure of the knee joint
- Tibiofemoral (knee) joint: largest and most complex diarthrosis of the body
- Primarily a hinge joint
- Capable of slight rotation and lateral gliding when knee is flexed
- Patellofemoral joint: gliding joint
- Popliteal (posterior) region: extracapsular ligaments, and intracapsular ligaments cross each other to form X
- Lateral meniscus and medial meniscus: C-shaped cartilages within joint capsule that absorb shock and prevent side-to-side rocking
98
What stabilizes the knee?
Quadriceps tendon in front
| Tendon of semimembranosus muscle on rear of thigh
99
Describe knee injuries
Highly vulnerable to rotational and horizontal stress; most common injuries are to the menisci and anterior cruciate ligament (ACL)
Heal slowly due to scanty blood flow
100
Knee joint: Describe the ACL and PCL
- Anterior cruciate ligament (ACL): prevents hyperextension of knee when ACL is pulled tight; common site of knee injury
- Posterior cruciate ligament (PCL): prevents femur from sliding off tibia
101
Describe the major features of the knee (talocrural) joint
- Medial joint: between tibia and talus
- Lateral joint: between fibula and talus
- Both articulations are enclosed by one joint capsule
- Malleoli of tibia and fibula overhang the talus on either side and prevent side-to-side motion
- Calcaneal (Achilles) tendon: extends from the calf muscles to the calcaneus
- Sprains (torn ligaments and tendons) are common at the ankle
102
Describe the two basic types of arthritis (osteoarthritis and rheumatoid arthritis).
1) Osteoarthritis (OA)—most common form of arthritis
- “Wear-and-tear arthritis”
- Results from years of joint wear
- Articular cartilage softens and degenerates
- Accompanied by crackling sounds called crepitus
- Bone spurs develop on exposed bone tissue causing pain
2) Rheumatoid arthritis (RA)—autoimmune attack against the joint tissues
- Misguided antibodies (rheumatoid factor) attack synovial membrane, enzymes in synovial fluid degrade the articular cartilage, joint begins to ossify
- Ankylosis: solidly fused, immobilized joint
- Remissions occur, steroids and aspirin control inflammation
103
List the functions of muscles.
Movement, stability, control of openings, heat production, and glycemic control
104
Describe how muscles help with movement
Move body parts (through pulling, never pushing); move body contents in breathing, circulation, and digestion
105
Describe how muscles help with stability
Maintain posture by preventing unwanted movements
| Stabilize joints by maintaining tension
106
Describe how the muscular system helps control openings and passageways
Sphincters: internal muscular rings that control the movement of food, blood, and other materials within body
107
Skeletal muscles are responsible for as much as __% of our body heat
85%
108
How does the muscular system help with glycemic control?
Muscles absorb and store glucose as glycogen which helps regulate blood sugar concentration within normal range
109
Describe the endomysium of muscles
Thin sleeve of loose connective tissue around each fiber
| Electrically insulates each muscle fiber
110
Describe the perimysium of muscles
Thicker layer of connective tissue that wraps fascicles
Carries nerves, blood vessels, and stretch receptors
Fascicles: bundles of muscle fibers wrapped together
111
Describe the epimysium of muscles
Fibrous sheath surrounding entire muscle
| Outer surface grades into fascia; inner surface projections form perimysium
112
Describe the fascia of muscles
Sheet of connective tissue that separates neighboring muscles or muscle groups from each other and the subcutaneous tissue
113
What is the order of the connective tissues surrounding muscle components from smallest to biggest?
Sheet of connective tissue that separates neighboring muscles or muscle groups from each other and the subcutaneous tissue
114
The ______ defined by the perimysium are oriented in a variety of ways that determine the strength of a muscle and the direction in which it pulls.
fasicles
115
List the various shapes of muscles and give examples of each
1) Fusiform: biceps brachii
2) Parallel: rectus abodomins
3) Triangular: pectoralis major
4) Unipennate: semimembranosus
5) Bipennate: rectus femoris
6) Multipennate: deltoid
7) Circular: orbicularis oculi
116
Define the origin, insertion, belly, action, and innervation of a muscle.
1) The attachment at the stationary end has been called the origin of the muscle
2) The attachment at the moving end has been called the insertion.
3) Innervation of a muscle: refers to the identity of the nerve that stimulates it
4) The effect produced by a muscle, whether it is to produce or prevent a movement, is called its action.
5) The widest part of a muscle is called the belly.
117
Define prime mover and fixator
1) The prime mover (agonist) is the muscle that produces most of the force during a particular joint action.
2) A fixator is a muscle that prevents a bone from moving. To fix a bone means to hold it steady, allowing another muscle attached to it to pull on something else.
118
Define synergist and antagonist
1) A synergist is a muscle that aids the prime mover. Two or more synergists acting on a joint can produce more power than a single larger muscle.
The actions of a prime mover and its synergist aren’t necessarily identical and redundant; it may stabilize the prime mover.
2) An antagonist is a muscle that opposes the agonist at a joint.
In some cases, it relaxes to give the prime mover almost complete control over an action. More often, however, the antagonist maintains some tension on a joint and thus limits the speed or range of the prime mover, preventing excessive movement, joint injury, or inappropriate actions.
119
Describe, in general terms, the nerve supply to the muscles and where these nerves originate.
Innervation of a muscle refers to the identity of the nerve that stimulates it. The nerves that innervate muscles are classified into two categories; spinal and cranial.
120
Facial muscles: Describe the actions of the frontalis, occipitalis, and orbicularis oculi muscles
Frontalis: wrinkles the forehead; lifts the eyebrows
Occipitalis: antagonist to frontalis
Orbicularis oculi: squinting and winking
121
Facial muscles: Describe the actions of the zygomaticus, risorius, and orbicularis oris
Zygomaticus: smiling (pulls the corners of the mouth up)
Risorius: pulls angle of the mouth laterally; synergist to the zygomaticus
Orbicularis oris: puckers the lips (kissing, whistling)
122
Facial muscles: Describe the actions of the mentalis, levator labii superioris, depressor labii inferioris, and genioglossus
Mentalis: protrudes lower lip as in pouting; wrinkles the chin.
Levator labii superioris: elevates the upper lip.
Depressor labii inferioris: pulls the lower lip down as in pouting.
Genioglossus: protrudes the tongue; moves tongue side to side.
123
Name and describe the actions of the muscles from lab lists used for chewing and swallowing.
1) Buccinator: compresses the cheeks; sucking (nursing infants); assists in chewing by directing the food between molars.
2) Temporalis and masseter: elevates the mandible (chewing)
124
Name and describe the actions of the neck muscles from lab lists that move the head. (2)
1) Sternocleidomastoid: flexes the head and neck
| 2) Trapezius: extension of the head and neck
125
Name and locate the muscles of respiration (from lab) (3)
1) Diaphragm: internal muscle that’s the prime mover for inhalation
2) External intercostals: muscle that elevates (lifts) the ribs that assist inhalation; increase size of thoracic cavity
3) Internal intercostals: muscles depress and retract the ribs for forced expiration; decreases size of thoracic cavity.
126
Name and locate the muscles from lab lists of the abdominal wall and back. (4)
1) Rectus abdominis: flexes the waist as in sit-ups; compresses abdominal viscera for urination, defecation, childbirth, and vomiting.
2) External oblique: most superficial muscle located on lateral abdomen; produces twisting at the waist and compresses abdominal viscera
3) Internal oblique: middle muscle layer on the lateral abdomen; produces twisting at the waist and compresses the abdominal viscera
4) Transverse abdominis: deepest muscle layer on the lateral abdomen; compresses abdominal viscera.
127
Name the origin and insertion of pectoralis major
Origin (medial): clavicle, cartilage of ribs 1-6, sternum
| Insertion (lateral): intertubercular groove, sulcus of the humerus
128
Name the origin and insertion of the deltoid
Origin (proximal): clavicle and acromion process of the scapula
Insertion (distal): deltoid tuberosity of the humerus
129
Name the origin and insertion of the latissimus dorsi
Origin (medial): spinous processes of T6-L5, iliac crest, and ribs 9-12
Insertion (lateral): intertubercular groove of the humerus
130
Name the origin and insertion of biceps brachii
Origin (proximal): coracoid process and glenoid cavity of the scapula
Insertion (distal): radial tuberosity
131
Name the origin and insertion of triceps brachii
Origin (proximal): posterior humerus and glenoid cavity of the scapula
Insertion (distal): olecranon process of the ulna
132
Describe the action of the deltoid
Abduction of the arm (prime mover); anterior fibers flex the arm, posterior fibers extend the arm
133
Describe the action of pectoralis major
Flexion and adduction of the arm (prime mover)
134
Describe the action of latissmus dorsi
Extension and adduction of the arm (prime mover)
135
Describe the action of teres major
Synergist to latissimus dorsi
136
Name the 4 rotator cuff muscles and describe their action
```
As a whole, stabilizes shoulder joint and rotates the humerus.
Supraspinatus
Infraspinatus
Teres minor
Subscapularis
```
137
Describe the action of serratus anterior and pectoralis minor
Protracts and laterally pulls scapulae forward
138
Describe the action of trapezius and levator scapulae
Elevates scapulae
139
Describe the action of trapezius and latissimus dorsi
Retracts scapulae
140
Describe the action of biceps brachii
Flexion and supination of the forearm
141
Describe the action of brachialis and brachioradialis
Flexion of the forearm
142
Describe the action of the pronator teres
Pronation of the forearm
143
Describe the action of triceps brachii
Extension of the forearm
144
Describe the action of the supinator
Supination of the forearm
145
The flexors of the wrist are located _______, whereas the extensors of the wrist are located ______.
anteriorly; posteriorly
146
Describe the action of the iliopsoas
Flexion of the hip (prime mover)
147
Describe the action of the rectus femoris
Flexion of the hip (synergist)
148
Describe the action of the sartorius
Flexion, abduction, and lateral rotation of the hip; flexion of the knee
149
Describe the action of the tensor fasciae latae
Abduction of the hip
150
Describe the action of the gluteus medius
Abduction of the hip (prime mover)
151
Describe the action of the gluteus maximus
Extension of the hip (prime mover)
152
Describe the actions of the hamstrings and name the muscles involved
```
Extension of the hip and flexion of the knee
Biceps femoris (lateral)
Semitendonosis (superficial)
Semimembranosus (deep)
Located on posterior thigh
```
153
Describe the action of the gracilis, abductor longus, and abductor magnus
Adduction of the hip
154
Describe the action of the quadriceps and name the muscles involved
```
Extension of the knee (all prime movers)
Rectors femoris (front of thigh)
Vastus lateralis (lateral)
Vastus medialis (medial)
Vastus intermedius (deep to rectus femoris)
```
155
Describe the action of the gastrocnemiuspl
Flexion of the knee
156
Walking on your tiptoes is called _______
plantar flexion
157
Describe the action of the tibialis anterior
Dorsiflexion (prime mover)
158
Describe the action of the gastrocnemius and soleus
Plantar flexion (prime movers)
159
Describe the action of the tibialis posterior
Inversion of the foot (prime mover)
160
Describe the action of the fibularis longus
Eversion of the foot
161
Name the origin and insertion of the gastrocnemius
Origin: medial and lateral condyles of the femur
Insertion: calcaneus
162
Describe the physiological properties that all muscle types have in common.
Muscles are specialized for one major purpose: converting the chemical energy in ATP into the mechanical energy of motion
Muscle functions include: movement, stability, control of openings, heat production, and glycemic control
163
List the defining characteristics of skeletal muscle.
```
Striated
Multinucleate
Excitable
Voluntary
Usually attached to bones
```
164
Muscles: Describe the endomysium
Thin sleeve of loose connective tissue around each fiber
| Electrically insulates each muscle fiber
165
Muscles: Describe the perimysium
Thicker layer of connective tissue that wraps fascicles
| Fascicles: bundles of muscle fibers wrapped together
166
Muscles: Describe the epimysium
Fibrous sheath surrounding entire muscle
| Outer surface grades into fascia; inner surface projections form perimysium
167
Muscles: Describe the fascia
Sheet of connective tissue that separates neighboring muscles or muscle groups from each other and the subcutaneous tissue
168
Define the sarcolemma and sarcoplasm of muscle cells
Sarcolemma: plasma membrane of a muscle fiber
Sarcoplasm: cytoplasm of a muscle fiber
169
Describe the myofibrils and glycogen of muscle cells
Myofibrils: long protein cords (most of sarcoplasm)
Glycogen: carbohydrate stored to provide energy for exercise
170
Describe the myoglobin and mitochondria of muscle cells
Myoglobin: stores some oxygen needed for muscle activity
Mitochondria: makes ATP
171
Why are muscle cells multinucleate?
Due to fusion of myoblast in development
172
Describe the t-tubules of muscle cells
Tubular infoldings of the sarcolemma which penetrate through the cell and emerge on the other side
173
Describe the sarcoplasmic reticulum (SR) of muscle cells
# Define as a smooth ER that forms a network around each myofibril:
- Terminal cisterns (cisternae): dilated end-sacs of SR
- Stores calcium
- Has two types of membrane proteins: a Ca+2 pump (pumps Ca+2 into the SR) and a Ca+2 voltage gate (releases Ca+2 into the sarcoplasm; opens in response to a voltage change)
174
Define a triad of a muscle cell
a T tubule and two terminal cisterns (cisternae)
175
Describe the striations seen on a myofibril
Striations result from the precise organization of myosin and actin in cardiac and skeletal muscle cells
Striations are alternating A-bands (dark) and I-bands (light)
176
Describe the A-band of a sarcomere and its components
A band: dark
Darkest part is where thick filaments overlap thin filaments
H band: not as dark; middle of A band; thick filaments only
M line: middle of H band
177
Describe the I-band of a sarcomere and its component
I band: light
| Z disc: provides anchorage for thin filaments and elastic filaments
178
Thick filaments are _____ proteins, whereas thin filaments are ______ proteins
contractile; regulatory
179
Describe the composition of thick filaments
Contractile proteins: myosin and actin do the work of contraction
Thick filaments: made up of mostly myosin molecules:
Each molecule shaped like a golf club
Two chains intertwined to form a shaft-like tail
Double globular head
180
Describe the composition of troponin and tropomyosin, as well as what they do
Regulatory proteins of thin filaments: turn contraction on & off
Tropomyosin: blocks active sites
Troponin: small protein on each tropomyosin molecule
181
Describe the composition and job of dystrophin
Dystrophin: a clinically important structural protein
Links outermost actin to membrane proteins that link to endomysium
Transfers forces of muscle contraction to connective tissue
Genetic defects in dystrophin produce muscular dystrophy
182
Describe elastic filaments and their job
A type of structural filament
Titin: huge, springy protein
Help stabilize and position the thick filament
Prevent overstretching and provide recoil
183
Discuss the necessity of the muscle cell being able to pull on the connective tissue layers in order to move the tendon attached to a bone.
Dystrophin is an enormous protein located between the sarcolemma and the outermost myofilaments. It links actin filaments to a peripheral protein on the inner face of the sarcolemma.
Through a series of linking proteins, this leads ultimately to the fibrous endomysium surrounding the muscle fiber. Therefore, when the thin filaments move, dystrophin transfers the force to the basal lamina, endomysium, and ultimately to the tendon.
Genetic defects in dystrophin are responsible for the disabling disease muscular dystrophy
Dystrophin is an enormous protein located between the sarcolemma and the outermost myofilaments. It links actin filaments to a peripheral protein on the inner face of the sarcolemma.
Through a series of linking proteins, this leads ultimately to the fibrous endomysium surrounding the muscle fiber.
Therefore, when the thin filaments move, dystrophin transfers the force to the basal lamina, endomysium, and ultimately to the tendon.
Genetic defects in dystrophin are responsible for the disabling disease muscular dystrophy
184
Explain what a motor unit is, the different types, and how it relates to muscle contraction.
1) Motor unit: one nerve fiber & all the muscle fibers innervated by it
2) Muscle fibers of one motor unit:
Dispersed throughout muscle
Contract in unison
Produce weak contraction over wide area
Provide ability to sustain long-term contraction as motor units take turns contracting
Effective contraction usually requires contraction of several motor units at once
3) Small motor units: fine degree of control
Three to six muscle fibers per neuron
Eye and hand muscles
4) Large motor units: more strength than control
Powerful contractions supplied by large motor units with hundreds of fibers
Gastrocnemius of calf has 1,000 muscle fibers per neuron
185
Describe the structure of the junction where a nerve fiber meets a muscle fiber.
Neuromuscular junction (NMJ): a synapse with a skeletal muscle
Synaptic knob: Contains synaptic vesicles with acetylcholine (ACh)
Schwann cell envelops and isolates NMJ
186
Describe the correct order of events at a neuromuscular junction.
1) Nerve impulse from axon opens calcium (Ca2+) channels
2) Ca2+ enters & causes synaptic vesicles to undergo exocytosis releasing ACh into synaptic cleft
3) Muscle cell has millions of ACh receptors (proteins; junctional folds increase surface area having ACh receptors)
4) Acetylcholinesterase (AChE) breaks down Ach, leading to relaxation
187
Explain why a cell has an electrical charge difference across its plasma membrane and, in general terms, how this relates to muscle contraction.
When a nerve or muscle cell is stimulated, dramatic things happen electrically; ion channels in the plasma membrane open and Na+ instantly flows into the cell, driven both by its concentration difference across the membrane and by its attraction to the negative charge of the cell interior; that is, it flows down an electrochemical gradient.
188
Explain how a nerve fiber stimulates a skeletal muscle fiber.
The electrical signal (nerve impulse) traveling down a nerve fiber cannot cross the synaptic cleft like a spark jumping between two electrodes; rather, it causes the synaptic vesicles to undergo exocytosis, releasing ACh into the cleft.
ACh then functions as a chemical messenger from the nerve cell to the muscle cell
189
Explain the stimulation of a muscle fiber
1) Nerve signal opens voltage-gated calcium channels in synaptic knob
2) Calcium enters knob and stimulates release of ACh from synaptic vesicles into synaptic cleft
3) ACh diffuses across cleft
4) Two ACh molecules bind to each receptor and open its channel
5) Na+ enters; shifting membrane potential from −90 mV to +75 mV
6) Then K+ exits and potential returns to −90 mV
The quick voltage shift is called an end-plate potential (EPP)
7) Voltage change in end-plate region (EPP) opens nearby voltage-gated channels producing an action potential that spreads over muscle surface
8) Action potential spreads down T tubules
9) Opens voltage-gated ion channels in T tubules & Ca+2 channels in SR
10) Ca+2 leaves SR and enters cytosol
190
Explain the contraction of a muscle fiber
1) Calcium binds to troponin in thin filaments
2) Troponin–tropomyosin complex changes shape and exposes active sites on actin
3) ATPase in myosin head hydrolyzes an ATP molecule
4) Activates the head (“cocking” it)
5) ADP + Pi remain attached
6) Head binds to actin active site forming a myosin–actin cross-bridge
7) Myosin releases ADP and Pi, and flexes pulling the thin filament with it—power stroke
8) Upon binding more ATP, myosin releases actin and process can be repeated
9) Recovery stroke recocks head
Each head performs five power strokes per second
Each stroke utilizes one molecule of ATP
191
Explain the relaxation of a muscle fiber
1) Nerve stimulation and ACh release stop
2) AChE breaks down ACh and fragments are reabsorbed into knob
3) Stimulation by ACh stops
4) Ca+2 pumped back into SR by active transport
5) Ca+2 binds to calsequestrin while in storage in SR
6) Ca+2 removed from troponin is pumped back into SR
7) Tropomyosin reblocks the active sites of actin
8) Muscle fiber ceases to produce or maintain tension
9) Muscle fiber returns to its resting length
Due to recoil of elastic components and contraction of antagonistic muscles
192
Explain why the force of a muscle contraction depends on the muscle’s length prior to stimulation.
Tension generated on muscle depends on how stretched the muscle is at the start
Overly contracted: so close to Z disc can’t contract much before hitting Z disc and stops
Overly relaxed: so little overlap, myosin can’t get grip on thin filaments
Optimum resting length: produces the greatest force when muscle contracts so nervous system maintains muscle tone (partial contraction) to ensure that resting muscles are near this length.
193
Explain why rigor mortis occurs in muscles after death.
Rigor mortis: hardening of muscles and stiffening of the body beginning 3-4 hours after death
Deteriorating sarcoplasmic reticulum releases Ca2+
Deteriorating sarcolemma allows Ca2+ to enter the cytosol
Ca2+ activates myosin-actin cross-bridging
Muscle contracts, but can’t relax because ATP is no longer being produced.
Muscle relaxation requires ATP, and ATP production is no longer produced after death
Fibers remain contracted until the myofilaments begin to decay
194
Rigor mortis peaks about __ hours after death, then diminishes over the next 48-60 hours.
12
195
Define a muscle twitch and describe its stages
Defined as a quick cycle of contraction and relaxation when stimulus is at threshold or higher
1) Latent period: a very brief delay between stimulus and contraction
2) Contraction phase: the period of time when muscle generates external tension
3) Relaxation phase: the period of time when tension declines to the baseline
196
Explain the physiological basis for recruitment.
Muscles must contact with variable strength for different tasks, so higher voltages excite more nerve fibers which stimulate more motor units to contract
Recruitment: the process of bringing more motor units into play with stronger stimuli; weak stimuli (low voltage) recruits small units, while strong stimuli recruit small and large units for powerful movements.
Recruitment or multiple motor unit (MMU) summation: occurs according to the size principle (smallest to largest)
197
Define tension and contraction, with respect to muscles.
Tension: refers to the condition in which muscles of the body remain semi-contracted for an extended period of time.
Contraction: the tightening, shortening, or lengthening of muscles when you do some activity.
198
Define isometric muscle contractions
Isometric muscle contraction: muscle produces internal tension but no movement
Important in postural muscle function and antagonistic muscle joint stabilization
199
Define an isotonic muscle contraction and name and describe its two types
Isotonic muscle contraction: Muscle changes in length with no change in tension
1) Concentric contraction: muscle shortens as it maintains tension (ex: lifting weight)
2) Eccentric contraction: muscle lengthens as it maintains tension (ex: slowly lowering weight)
200
Describe the phosphagen system of immediate energy.
Phosphagen system: the combination of ATP and CP (creatine phosphate) which provides nearly all energy for short bursts of activity
The amount of CP drops rapidly at the onset of exercise.
Until the respiratory and cardiovascular systems catch up with the heightened oxygen demand, the muscle meets most of its ATP needs by borrowing phosphate groups (Pi) from other molecules and transferring them to ADP.
Two enzyme systems control these phosphate transfers:
Myokinase transfers Pi from one ADP to another, converting the latter to ATP that myosin can use.
Creatine kinase obtains Pi from a phosphate-storage molecule, creatine phosphate (CP), and donates it to ADP to make ATP. This is a fast-acting system that helps to maintain the ATP level while other ATP-generating mechanisms are being activated
201
Describe anaerobic fermentation
Occurs in cytoplasm
Glycolysis: glucose broken down into pyruvic acid which is converted to lactic acid
2 ATP produced per glucose
No oxygen required
Produces enough ATP for 30 to 40 seconds of maximum activity
202
Describe aerobic respiration
After ~ 40 seconds, respiratory & cardiovascular deliver O2 fast enough for aerobic respiration to meet most of muscle’s ATP demand~30 minutes energy comes equally from glucose and fatty acids
Aerobic respiration produces more ATP per glucose than glycolysis does (another 30 ATP per glucose)
Occurs in mitochondria
Pyruvic acid broken down into CO2 and water
Must have oxygen present (used to form the water)
32-38 ATP generated (40% of the energy); rest is released as heat (60%)
> 30 minutes, depletion of glucose causes fatty acids to become the more significant fuel
203
List some factors that may contribute to muscle fatigue.
Muscle fatigue: progressive weakness from prolonged use of muscles
Fatigue in short duration exercise can result from:
Excess ADP and Pi slow cross-bridge movements, inhibit calcium release and decrease force production in myofibrils
Excess lactic acid, which decreases pH.
Fatigue in long duration exercise can result from:
Fuel depletion
Electrolyte loss
204
List some factors that increase the force of skeletal muscle contractions.
Large number of muscle fibers being activated
Large individual muscle fibers
High frequency of stimulation
Muscle and sarcomere are stretched to slightly over 100% of their resting length.
205
Describe the characteristics of cardiac muscle
Their cells are myocytes, which are not as long and fibrous as skeletal muscles; they have one nucleus
Highly resistant to fatigue
Keeps cardiac failure from occurring every time you engage in strenuous exercise
They are involuntary and controlled by the autonomic nervous system
Works in sleep or wakefulness, without fail, and without conscious attention, so our hearts don’t stop every time we fall asleep.
Contracts with regular rhythm
Muscle cells of a given chamber must contract in unison
Contractions must last long enough to expel blood
Autorhythmic
Cardiomyocytes joined by intercalated discs
Gap junctions and desmosomes; desmosomes are important to keep the cardiomyocytes from breaking apart, and gap junctions are necessary for synchronization and communication.
Sarcoplasmic reticulum less developed, so must use Ca^(2+) from extracellular fluid
Damaged cardiac muscle cells repair by fibrosis; functional muscle not regenerated
Almost exclusively aerobic respiration
206
Describe the characteristics of skeletal muscle
Both aerobic and anaerobic respiration
Long, multinucleate fibrous cells
A more developed sarcoplasmic reticulum
Not autorhythmic, and they’re voluntary and controlled by the somatic nervous system
Functional skeletal muscle can be regenerated
207
Describe the characteristics of smooth muscle
No striations
Some smooth muscles lack nerve supply; others receive input from autonomic fibers containing synaptic vesicles
Capable of mitosis and hyperplasia
Injured smooth muscle regenerates well
Smooth muscle is slower than skeletal and cardiac muscle
Require extracellular Ca+2
Takes longer to contract but can remain contracted for a long time without fatigue
