Structures And Functions Of The Shoulder And Brachial Regions

Question 1

Name the different regions of the forelimb

Answer 1

OMO-shoulder
BRACHIUM-arm(region from shoulder to elbow)
ANTEBRACHIUM-forearm (region from elbow to carpus)
CARPUS-wrist
MANUS-hand (region distal to carpus)
DIGIT-toe

Question 2

What type of bone is the scapula?

Answer 2

Type of flat bone

Question 3

What is the glenoid cavity?

Answer 3

• articular surface (shoulder joint)
• concave
• smooth muscle

Question 4

What is the function of the supraglenoid tubercle?

Answer 4

-attachment of biceps branchii muscle

Question 5

Describe the structure and attachments of the medial/costal surface

Answer 5

Serrated, rough bone

Attachment of:
Serratus ventralis muscle (dorsal)
Subscapularis muscle. (Ventral)

Question 6

How does the scapula different in a cat compared to a dog?

Answer 6

More rounded cranial angle than dog
Has a suprahamate process proximal to the acromion process
Has tuberosity of spine

Question 7

Where are the centres of ossification in bone? What are the potential clinical problems associated with these centres of ossification?

Answer 7

Body, supraglenoid tubercle

Potential problems

• tendon of origin of biceps branchii muscle
• physis weak point= fracture

Question 8

What bony structures of the scapula can we palpate in live animals?

Answer 8

• dorsal border
• cranial border
• cranial angle
• spine
• acromion

CAUDAL BORDER BENEATH MUSCLE SO IS DIFFICULT TO PALPATE

Question 9

Where does the brachiocephalic muscle originate and insert? What is its function?

Answer 9

Cephalic=head
Insertion=arm

Origin=cervical-thoracic fascia
Insertion= humerus

Function= protractor
-also acts across shoulder

Question 10

What are the 3 parts of the brachiocephalic muscle called?

Answer 10

Cleidocervicalis, cleidomastoideus, cleidobrachialis

Question 11

Where does the omotransversarius originate and insert? What is its function?

Answer 11

Origin=transverse wing of the atlas (C1)
Insertion=acromion process
Function=protracts the limb
RUNS UNDER THE BRACHIOCEPHALIC MUSCLE

Question 12

How are the radiographs of dogs and cats different?

Answer 12

Dogs will have a clavicular band (fibrous band) while cats will have a clavicle (bony remnant) cranial to shoulder

Question 13

Where does the latissimus dorsi muscle originate and insert? What is its function

Answer 13

Latus=broad dorsi=back

Origin=thoracolumbar fascia
Insertion=humerus (aponeurosis)
Function=retractor

Question 14

Where is the serratus ventralis muscle located and where does it originate and insert?

Answer 14

Muscle located between forelimb and trunk

Origin=thoracic wall (ribs) and cervical vertebrae (neck)
Insertion=proximal scapula (medial aspect), proximal to pivotal joint

Function
CRANIAL PORTION:retractor
CAUDAL PORTION:protractor
No effect on the shoulder

Question 15

What are abductor and adductor muscles?

Answer 15

Abductors-move limb away from midline (muscles located proximal to pivot point and limb)

Adductors: move limb towards the midline
Located distal to pivot point and medial to limb
Limited movement

Question 16

Where does the trapezius muscle originate and insert?

Answer 16

Origin=cervicothoracic fascia
Insertion=proximal scapular spine
No effect on the shoulder, has cranial and caudal parts

Question 17

Where does the rhomboideus muscle originate and insert? What is its function?

Answer 17

Lies deep in trapezius
ORIGIN- cerviothoracic fascia
INSERTION-dorsal border of scapula
Function= abductors of limb, no effect on shoulder

Question 18

Describe the structure and function of the pectoral muscles. Where do they originate and insert?

Answer 18

Origin=sternum
Insertion=humerus
2 heads-deep and superficial
Adductor of limb (move towards midline)

Question 19

What features are located at the proximal end of the humerus bone?

Answer 19

HEAD- articular surface, convex and smooth surface. Articulates with glenoid cavity of scapula at shoulder joint
GREATER TUBERCLE- lateral aspect
LESSER TUBERCLE-medial aspect
INTER-TUBERCULAR GROVE -smooth bone surface, tendon of origin of biceps branchii muscle passes through this structure

Question 20

What features are located at the distal end of the humerus?

Answer 20

CONDYLE: medial half longer than lateral 
MEDIAL EPICONDYLE(larger)
LATERAL EPICONDYLE(SMALLER) 

Articular surface (elbow joint) is divided into 2 areas: 
TROCHLEA-pulley like structure, larger. Central depression, articulates with radius and ulna 
CAPITULUM-smaller,located laterally, articulates with radius 

OLECRANON/ULNAR FOSSA(caudal) 
RADIAL FOSSA(cranial)-proximal to articular surfaces 
SUPRATROCHLEAR FORAMEN-nothing passes through, may not be present in short legged dogs

Question 21

How many centres of ossification does the humerus have and where are these located?

Answer 21

Ossification centres;
-proximal epiphyses
-body 
In condyle:
-medial epicondyle 
-medial half of condyle 
-lateral half of condyle

Question 22

What parts of the humerus can be palpated?

Answer 22

• greater tubercle
• lateral epicondyle
• medial epicondyle

Question 23

How is the humerus different in cats from dogs?

Answer 23

Proximal end is the same
Distal end-no supracholear foramen
Has a supracondylar foramen (brachial artery and median nerve pass through it)