The proximal forelimb and the shoulder joint Flashcards

1
Q

Give 3 examples of cursorial adaptations.

A
  1. Reduced pectoral skeleton
    (More cranial/ caudal movement
    Clavicle absent / vestigial
    Deep, narrow chest)
  2. Elongation at proximal end of limb (scapula lies lateral and vertical)
  3. Elongation at distal end of limb
    (long metacarpals)
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2
Q

What is the name for the shoulder region in the forelimb?

A

Omo

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3
Q

What is the name for the region from the shoulder to the elbow?

A

Brachium

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4
Q

What is the name for the region that goes from the elbow to the carpus?

A

Antebrachium

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5
Q

What is the name for the wrist?

A

carpus

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6
Q

What is the name for the region proximal to the digit and distal to the carpus?

A

Manus

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7
Q

List the bones of the forelimb in order from proximal to distal.

A

Scapula, humerus, radius and ulna, carpal bones, metacarpal bones, phalanges

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8
Q

What is the benefit of the verticle orientation of the scapula in cursorials?

A

Increases limb length => increase in stride length => more ground covered

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9
Q

True or False?
A clavicle helps attach the forelimb to the trunk in cursorials.

A

FALSE

There is only muscular attachment

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10
Q

What animal still has a clavicle?

A

Cat

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11
Q

What type of bone is the scapula?

A

Flat bone

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12
Q

What border of the scapula is beneath muscle so is therefore difficult to palpate?

A

Caudal border

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13
Q

What part of the scapula should be used as a guide for location of the shoulder joint?

A

Acromion process

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14
Q

What does the scapular spine divide?

A

Supraspinous fossa
Infraspinous fossa

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15
Q

What is at the ventral surface of the scapula?

A

Glenoid cavity and the superglenoid tubercle

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16
Q

What part of the scapula is the biceps brachii muscle attached to?

A

superglenoid tubercle

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17
Q

Describe the surface of the glenoid cavity.

A

Concave, smooth subchondral / articular surface for shoulder joint

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18
Q

What muscles are attached to the rough costal (medial) side of the scapula?

A

Serratus ventralis muscle (dorsal)
Subscapularis muscle (ventral)

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19
Q

What are 2 differences that might be seen between a cat and dogs scapula?

A

Cats scapulas have a more rounded cranial angle then dogs

Cats have a suprahamate process
(proximal to acromion process)

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20
Q

What are features seen in a scapula of larger species?

A

They have a tuber (bony bump) on the spine and have a cartilage extension to the dorsal border

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21
Q

How many centres of ossification does the scapula have?

A

2

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22
Q

What are the centres of ossification in the scapula?

A
  • Body
  • Supraglenoid tubercle
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23
Q

What type of bone is the humerus?

A

Long bone

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24
Q

What does the head of the humerus articulate with to form the shoulder joint?

A

Glenoid cavity of scapula

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25
What makes up the head of the humerus?
- Greater tubercle (lateral) - Lesser tubercle (medial) - Intertubercular groove
26
What passes through the intertubercular groove?
Biceps tendon
27
Which side is the greater tubercle located on?
Lateral side (therefore is palpable)
28
What is located at the distal end of the humerus?
Condyle
29
How can muscle attach to bone?
- Directly to the rough surface of bone or bumps/tubercles - Via an aponeurosis - Via tendons
30
What happens when the muscle fibres contract?
The muscle belly shortens and the points of attachment are pulled closer together
31
What is the meanning of antagonistic pairs?
They have equal but opposite actions
32
What does the action of a joint depend on?
- Specific joint crossed - Aspect of joint crossed
33
Where would the origin and insertion of an extrinsic muscle be?
Origin: axial skeleton Insertion: appendicular skeleton
34
Protraction
limb moves crainally
35
Retraction
limb moves caudally
36
Adduction
Limb moves medially
37
Abduction
Limb moves laterally
38
Where would the origin and insertion of an intrinsic muscle be?
Both in appendicular skeleton
39
What movements are associated with intrinsic muscles?
- Flexion - extension - rotation
40
What movements are assocaited with extrinsic muscles?
- Protraction - Retraction - Adduction -Abduction
41
Flexion
Reduced flexor angle (non-weight bearing position)
42
Extension
Increased flexor angle (weight bearing position)
43
What is the O and I of the brachiocephalic muscle?
O- cervical vertebrae and skull I- Humerus
44
What type of muscle is the brachiocephalic muscle?
Extrinsic muscle
45
Is the brachiocephalic muscle located over the cranial or caudal aspect of the forelimb?
cranial
46
Where is the flexor angle located in the shouder joint?
Caudally
47
What is the function of the brachiocephalic muscle in relation to the limb and joints?
Forelimb protractor Shoulder extensor
48
In what animal is the vestigual clavicle still embedded in the brachiocephalic muscle?
cat
49
Where is the origin and insertion of the latissimus dorsi muscle?
O- Thoracic vertebrae I - humerus
50
What does latissimus dorsi literally translate to?
broadest muscle of the back
51
Does the latissumus dorsi insert onto the cranial or caudal humerus?
Caudal (located caudal to the limb)
52
In realtion to the forlimb what is the function of the latissumus dorsi?
Forelimb retractor Shoulder flexor
53
What is the antagonistic pair of the lastissumus dorsi?
brachiocephalic muscle
54
Where is the origin and insertion of the serratus ventralis muscle?
O - cervical vertbrae and thoracic wall(ribs) I- Medial aspect of the proximal scapula around the dorsal border
55
What is the serratus ventralis muscle located between?
the forelimb and the trunk
56
What is the function of the cranial portion of the serratus ventralis muscle?
Forelimb retractor
57
What is the function of the caudal portion of the serratus ventralis muscle?
Forelimb protractor
58
Describe the insertion of the serratus ventralis muscle with regards to the pivotal point?
Proximal to the pivotal point
58
Explain how the caudal portion of the serratus ventralis muscle results in protraction of the forelimb.
Because the insertion is proximal to the pivotal point when the caudal portion of the muscle contracts it pulls the dorsal border of the scapula caudally and the rotates the distal end of the scapula crainally which results in protraction.
59
Explain how the cranial portion of the serratus ventralis muscle results in retraction of the forelimb.
Because the insertion is proximal to the pivotal point when the cranial portion of the muscle contracts it pulls the dorsal portion of the scapula cranially and rotates the distal end of the scapula caudally which results in retraction.
60
Where is the O and I of the trapezius muscle?
O- cervical and thoracic vertebrae I- proximal scapular spine
61
Where is the trapezius muscle located?
Proximal to the forelimb and the pivotal point
62
How many parts does the trapezius muscle have?
2 (cranial and caudal)
63
What is the function of the trapezius muscle?
ABDUCTION (also protraction)
64
The main function of the trapezius muscle is abduction but it also contributes to protraction. How does it contribute to this?
When the 2 heads contract they pull the dorsal border of the scapula in a caudal direction which will have an effect on the rotation of the distal end of the scapula moving it crainally.
65
Where is the O and I of the pectoral muscles?
O- sternum i- humerus
66
Where are the pectoral muscles located in relation to the pivotal point?
distal to the pivotal point
67
Where are the pectoral muscles located in relation to the limb?
Medially
68
How many heads do the pectoral muscles have?
2 (deep and superficial groups)
69
What is the function of the pectoral muscles?
Adduction
70
What is the antagonistic muscle of the pectoral muscle?
Trapezius
71
What extrinsic muscles do not recieve their nerve supply from the brachail plexus?
Brachiocephalic (toocranial) Trapezius (too dorsal)
72
Name the joints of the forelimb (proximal to distal)
Shoulder joint, elbow joint, carpal joint, metacarpophalangeal joints, inter phalangeal joints
73
What animal does not have an acromion process?
horse
74
What is the name for the shaft of the humerus?
Body
75
What lies between the medial and lateral epicondyles of the humerus?
Trochlea
76
What is the humerus articular surface for the elbow joint?
Trochlea
77
What is the name for the foramen above the trochlea?
Supratrochlear foramen
78
True/False? Nothing passes through the supratrochlear foramen.
True
79
Does the cat have a supratrochlear foramen?
NO!
80
What is the name for the foramen present in the distal humerus of cats that allows passage of the brachial artery and median nerve?
Supracondyloid foramen
81
Is the supratrochlear foramen present in larger species?
NO they have to bear weight on limbs a lot and a very heavy
82
How many centres of ossification are present in the humerus?
5
83
What are the 5 centres of ossification in the humerus?
1. Proximal epiphyses 2. Body condyle: 3. Medial epicondyle 4. Medial half 5. Lateral half
84
What are the components of the shoulder joint?
- Glenoid cavity of scapula - Head of humerus
85
Why does the shoulder joint differ from a typical synovial joint?
It has weak collateral ligaments
86
What are the palpable landmarks that would indicate the position of the shoulder joint?
- Acromion process - Greater tubercle
87
Which aspect of the shoulder joint does the bicep tendon run over?
Cranial aspect (through the intertubercular groove)
88
Where is the Biceps Brachii located?
Brachial region on the cranial aspect of humerus
89
What ligament holds the bicep tendon in place?
Transverse ligament
90
What is the bicipital bursa?
An out-pouching of the shoulder joint capsule into the intertubercular groove where it envelopes the origin of the biceps brachii tendon
91
What muscles provide lateral support to the shoulder joint?
Supraspinatous muscle and infraspinatous muscle
92
What muscles provides medial support to the shoulder joint?
Subscapularis muscle
93
What is the O and I of the supraspinatous muscle?
O- supraspinatous fossa I- proximal lateral humerus
94
What is the O and I of infraspinatous muscle?
O- infraspinatous fossa I- Proximal lateral humerus
95
What nerve supplies the infraspinatous and supraspinatous muscles?
Suprascapular nerve
96
What is the O and I of the subscapularis muscle?
O- subscapular fossa I - Proximal medial humerus
97
What nerve supplies the subscapularis muscle?
Subscapular nerve