Structures And Functions Of The Antebrachial Region

Question 1

What type of bones are the radius and the ulna? Compare the length and function of the two

Answer 1

They are long bones that are paired and cross over each other obliquely

ULNA-longer and leverage
RADIUS-shorter and main weight bearing

Question 2

Describe what features are present at the proximal end of the radius bone

Answer 2

Head-fovea capitis
Articular surface=elbow joint
Neck

Question 3

What features are located on the distal end of the radius bone?

Answer 3

Trochlea-articular surface (carpus)
Styloid process-medial, attachment of medial collateral ligament of carpus
Ulnar notch

Question 4

What features are located at the proximal end of the ulna?

Answer 4

• olecranon process
• anconeal process (beak shaped, fits into olecranon/ ulnar fossa of humerus)
• Trochlear notch (articular surface-elbow joint)
• lateral coronoid process
• medial coronoid process
• radial notch (articulates with the radius)

Question 5

What features are located at the distal end of the ulna bone?

Answer 5

Styloid process-attachment of lateral collateral ligament of carpus

Question 6

Describe the proximal articulation of the radius and ulna

Answer 6

• radius (head)
• radial notch of the ulna
• held by annular ligament (runs lateral to medial coronoid process, rotation possible)

Question 7

Describe the distal articulation of the radius and ulna

Answer 7

• fibrous joint
• some rotation possible
• interosseous space between bodies, interosseous ligament and fibrous joint

Question 8

Describe the evolution of the radius and the ulna. Which bone is projected medially and laterally at the proximal and distal ends of the bone

Answer 8

Toes rotated cranially, elbows rotated caudally (therefore radius and ulna rotate around each other)
PROXIMAL: ulna is the most medial projection
DISTAL: ulna is the most lateral projection

Question 9

What parts if the ulna and radius can you palpate?

Answer 9

Ulna-olecranon process, lateral styloid process

Radius- medial styloid process

Question 10

How is the ulna and radius different in dogs and cats?

Answer 10

Cats;

• square olecranon
• radius and ulna are similar diameter

Question 11

Where are the centres of ossification found on the radius and ulna bone?

Answer 11

Radius- proximal epiphyses,body,distal epiphyses (TOTAL=3)

Ulna-olecranon process, anconeal process, body, distal epiphyses
TOTAL=3

Question 12

Describe the parts of the humerus which articulate with the ulna/radius

Answer 12

Trochlea- articulates with trochlear notch of the ulna and fovea capitis of the radius
Capitulum- articulates only with fovea capitis of the radius

Question 13

Describe how stability of the elbow joint is maintained

Answer 13

COLLATERAL LIGAMENTS: humerus, radius and ulna

BONEY STRUCTURES- anconeal process (ulna) and olecranon/ulnar fossa (humerus)

Question 14

Describe how movement occurs at the joint between the radius and the ulna

Answer 14

-limited to flexion and extension
-ulna acts as a lever
-elbow extensors insert onto he olecranon
AVULSION POSSIBLE

Question 15

Describe the structure and how movement occurs at the joint between the radius and the ulna

Answer 15

• rotation is possible
• annular ligament
• interosseous ligament
• fibrous joint distally (pronation=face down and supination is face up)

In dogs there is limited rotation and in cats there’s a large amount of rotation

Question 16

Identify and describe the elbow extensors found at the elbow joint. What is its nerve supply?

Answer 16

Elbow extensors- caudal to elbow joint and insert onto the olecranon process

TRICEP MUSCLE:
Long head originates at the caudal border of the scapula (also is a shoulder flexor)
Lateral head originates at the lateral aspect of the humerus
The medial head originates at the medial aspect of the humerus
The accessory head

Motor nerve supply-radial nerve

Question 17

Identify the elbow flexors at the elbow joint. What is their nerve supply?

Answer 17

Elbow flexors are cranial to the elbow joint

BICEPS BRACHII MUSCLE:
Originates at the superglenoid tubercle and inserts on the proximal radius

BRACHIALIS MUSCLE:
Originates at the caudal aspect of the humerus
Inserts on the proximal radius
It follows the musculospiral/brachial groove

MOTOR NERVE SUPPLY VIA THE MUSCULOCUTANEOUS NERVE

Question 18

Identify and describe the rotator muscles found at the elbow joint

Answer 18

SUPINATOR MUSCLE- originates at the lateral epicondyle
Supplied by the radial nerve

PRONATOR TERES MUSCLE: originates at the medial epicondyle and inserts on the proximal radius. It is supplied by the median nerve

Question 19

Where would you dissect to get access to the humerus

Answer 19

Between muscles so there’s less damage and therefore faster healing

To access the proximal humerus- dissect between the brachiocephalicus and the deltoideus
To access the midshaft, dissect between the brachiocephalicus and brachialis
To access the distal humerus, dissect between the brachialis and the triceps

Question 20

Why do blood vessels cross flexor aspects of the joints?

Answer 20

It avoids stretching of the vessels

Question 21

Where does the subclavian artery run?

Answer 21

Runs around the 1st rib to the axilla

Question 22

Where does the axillary artery run?

Answer 22

Runs through the axilla

Question 23

Where does the brachial artery run?

Answer 23

Runs down the brachium

Question 24

What does the brachial artery artery branch into and where does this branch run?

Answer 24

Brachial artery runs into the median artery, which runs runs down the medial aspect of the antebrachium

Question 25

What does the median artery run into and where do these run to?

Answer 25

Median artery branches into:

1. Radial artery- terminates in superficial palmar branch
2. Superficial brachial artery- runs down the cranial aspect of the antebrachium

Question 26

Describe the palmar blood supply of a animal

Answer 26

Median artery- supplies the superficial palmar arch and palmar common digital arteries

Caudal interosseus artery- supplies the deep palmar arch, palmar common digital/ metacarpal arteries and digital arteries

Question 27

Describe the dorsal blood supply of the forelimb

Answer 27

Superficial brachial artery (superficial dorsal supply to forepaw). It supples the dorsal common digital arteries and dorsal digital arteries

Question 28

What happens when the blood supply reaches the digit?

Answer 28

Supplies fuse and then branch so that each digit has 4 vessels supplying it

Question 29

Describe what is meant by the terms deep and superficial systems in the venous blood supply

Answer 29

Deep= follows arterial supply, VAN

Superficial system- cephalic vein, drains into the jugular vein/ vena cava

Question 30

What clinical considerations would you have to have when taking a blood sample from the cephalic vein?

Answer 30

-pressure required to raise the vein, must release pressure before you inject
Must ensure fluid enters the vein and not subcutaneous tissue
Radial nerve runs alongside the cephalic vein
(PROVIDES CUTANEOUS SENSATION TO CRANIAL ASPECT OF THE FORELIMB)