Muscles and Joints (Extrinsic back)

Question 1

Define a joint:

Answer 1

The place where 2 or more bones make contact - articulation

Question 2

What are the 3 structural classifications of joints? Give a breif overview and an example of each:

Answer 2

Fibrous - bones joined by dense connective tissue (e.g. sutures)
Cartilaginous - bones joined by cartilage (e.g. IVDs)
Synovial - bones that are not directly joined, allows movement (limited by shape of synovial joint) (e.g. shoulder joint)

Question 3

What are the 3 functional classifications of joints? Give examples for each:

Answer 3

Synarthrosis - no movement (e.g. sutures, sunchondrosis, synostosis)
Amphiarthrosis - little movement (e.g. distal tibiofibular, pubic symphysis)
Diarthrosis - free movement (e.g. synovial joints)

Question 4

What is a continuous joint?

Answer 4

A joint where the two bones are linked by fibrous or cartilaginous tissue

Question 5

What is the structure of a synovial joint? (Draw it)

Answer 5

Articular surfaces, articular cartilage, articular space filled with synovial fluid, articular capsule lined by synovial membrane, ligaments strengthening the capsule, muscle to increase stability, other additional devices

Question 6

What are the different shapes of synovial joints

Answer 6

Uniaxial:
- Pivot: rounded process of bone fits in bony ligamentous socket permitting rotation (e.g. atlanto-axial joint)
- Hinge: permits flexion and extension only (e.g. elbow joint)
- Plane: permits gliding or sliding movements (e.g. acromioclavicular joints)

Biaxial:
- Condyloid: permit flexion and extention, abduction and adduction and circumduction (e.g. metacarpophalangeal joint)
- Saddle: saddle- shaped heads permit movement in 2 different planes (e.g. carpometacarpal joint)

Multiaxial:
- Ball and socket: rounded head fits into concavity permitting movement on several axes (e.g. hip)

Question 7

What are the 3 types of Muscle?

Answer 7

Skeletal, Cardiac, Smooth

Question 8

Location of skeletal striated muscle?

Answer 8

Composes gross named muscles attached to skeleton and fascia of limbs, body wall and head/neck

Question 9

Appearance of cells in skeletal striated muscle?

Answer 9

• Large, very long, unbranched, cylindrical fibres
• Transverse straiation
• Arranged in parallel bundles
• Multiple, peripherally located nuclei

Question 10

Type of activity of skeletal striated muscle?

Answer 10

• Intermittent contraction above a baseline tonus
• Acts mainly to produce movement rhough shortening or controlled relaxation

Question 11

Stimulation of skeletal muscle?

Answer 11

Voluntary or reflective by somatic nervous system

Question 12

Location of cardiac muscle?

Answer 12

Heart and portions of adjacent great vessels

Question 13

Appearance of cells in cardiac muscle?

Answer 13

• Branching and anastamosing shorter fibres
• Transverse striations running parallel and connected end to end by complex junctions
• Single central nucleus

Question 14

Type of activity of cardiac muscle?

Answer 14

• Strong, quick, continous rythmic contractions
• Pumbs blood from heart

Question 15

Stimulation of cardiac muscle

Answer 15

Involuntary
Intrinsically stimulated and propogated
Rate and strength of contraction modified by autonomic nervous system

Question 16

Location of smooth muscle

Answer 16

Walls of hollow viscera and blood vessels, iris and ciliary body of the eye
Attached to hair follicles of skin

Question 17

Appearance of cells in smooth muscle?

Answer 17

Single or agglomerated (gathered in clusters) cells
Small spindle shaped fibres without striations
Single central nucleus

Question 18

Type of activity of smooth muscle?

Answer 18

• Weak, slow, rythmic or sustained contraction
• Mainly acts to propel substances (peristalsis, vascular pulsation) and to restrict flow (vasoconstrinction, sphincteric activity)

Question 19

Stimulation of smooth muscle?

Answer 19

Involuntary by autonomic or enteric nervous systems

Question 20

Functions of Muscular System

Answer 20

Skeletal muscle only: Locomotion, stablity, posture, protection, respiration
Combination of muscles: circulation, digestion, urination, childbirth, vision, temperature regulation

Question 21

What does the range of movement and strength of a muscle depend on?

Answer 21

Range of movement dependent on fibre length (can contract to 30% of their length)
Strength of muscle depenent on number of fibres

Question 22

List and describe the 6 muscle classifications:

Answer 22

Flat muscles: parallel fibres often with aponeurosis (e.g. external oblique)
Pennate muscles: feather-like, can have unipennate (e.g. extensor digitorum longus), bipennate (e.g. rectus femoris) and multipennate (e.g. deltoid)
Fusiform: spindle shaped with a round thick belly and tapered ends (e.g. biceps brachi)
Convergent: arise from a broad area and converge to form a single tendon (e.g. pectoralis major)
Quadrate: four equal sides (e.g. rectus abdominis)
Circular/ sphincteral muscles: surround a body opening or orifice (e.g. orbicularis occuli)

Question 23

What type of muscle is the biceps brachii? Where does it originate and insert? What movement does it cause?

Answer 23

• Fusiform muscle with two heads
• Originates: long head at supraglenoid tubercle and short head at the coracoid process
• Inserts at the radial tuberosity
• Crosses sholder and elbow so can cause flexion at both joints (and supination of forearm)

Question 24

What are the 4 layers of the body?

Answer 24

Skin (epidermis, dermis)
Subcutaneous tissue/ superficial fascia (adipose tissue)
Deep pascia - forms compartments surrouding muscles in the limbs
Muscle

Question 25

Define the two catagories of back muscle and state the nerve group supplying them:

Answer 25

Extrinsic back muscles:
- act on structures outside the back (appendicular skeleton)
- innervated by anterior rami of spinal nerves

Intrinsic back muscles:
- act on structures within the back
- innervated by dorsal rami of spinal nerves

Question 26

What are the 4 Posterior Axioappendicular Muscles? Divide them into 2 catagories:

Answer 26

Define: group of muscles arising from the axial skeleton which act upon the pectoral girdle (extrinsic back muscles)
Superficial:
- Trapezius
- Latissimus Dorsi
Deep:
- Levator Scapulae
- Rhomboids (major and minor)

Question 27

What are the origins and insertions of the trapezius?

Answer 27

Origins:
- superior nuchal line
- nuchal ligament
- C7 to T12 spinous processes
Insertions:
- Descending: lateral third clavicle
- Horizontal: acromion of scapula
- Ascending: spine of scapula

Question 28

What are the actions of the trapezius on the shoulder girdle, head/neck and vertebral column?

Answer 28

Action on shoulder girdle:
- Descending muscles keep shoulder girdle up and tilts scapula for arm elevation
- Horizontal and ascending muscles depress and pull scapula medially
Actions on head and neck:
- Descending muscles: with fixed shoulder lead to contralateral rotation (looking to side) or extension
Actions on vertebral column: flattens thoracic kyphosis

Question 29

What is the nerve supply to the trapezius muscle?

Answer 29

Cranial nerve XI Accessory (+ cervical pl.)

Question 30

What are the origins and insertions of the latissimus dorsi?

Answer 30

Origins:
- spinous processes T7-T12
- Thoraco-lumbar aponeurosis
- Dorsal surface of sacrum
- Dorsal 1/3 of the iliac crest
- 10th-12th rib
- Inferior angle of scapula (variable)
Insertions:
- Humerus: floor of intertubercular sulcus

Question 31

Actions of the latissimus dorsi:

Answer 31

On arm:
- adduction
- internal (medial) rotation
- extension
On trunk:
- elevation (with arm fixed on a bar)
On shoulder girdle:
- depression
- Pulls scapula medially

Question 32

Nerve supply of latissimus dorsi

Answer 32

Thoraco-dorsal nerve from brachial plexus

Question 33

Origins and insertion of rhomboid major and minor:

Answer 33

Origins
- Minor: spinous processes C6-C7
- Major: spinous processes T1-T4
Insertions:
- Medial margin of scapula
-Minor: root of scapular spine
- Major: below scapular spine

Question 34

Action of Rhomboids:

Answer 34

On shoulder Girdle:
- retract scapula
- rotate glenoid inferiorly
- Fix scapular to trunk

Question 35

Nerve supply of rhomboids:

Answer 35

Dorsal scapular nerve from brachial plexus

Question 36

Attachments of Levator scapulae

Answer 36

• Vertebrae C1-C4 transverse processes
• Scapula superior angle

Question 37

Actions of levator scapulae

Answer 37

On shoulder girdle:
- elevates scapula and rotates glenoid inferiorly
On vertebral column:
- with fixed shoulder girdle it extends the neck

Question 38

Nerve supply to levator scapulae

Answer 38

Dorsal scapular nerve from brachial plexus