Structures And Functions Of The Antebrachial Region Flashcards
What type of bones are the radius and the ulna? Compare the length and function of the two
They are long bones that are paired and cross over each other obliquely
ULNA-longer and leverage
RADIUS-shorter and main weight bearing
Describe what features are present at the proximal end of the radius bone
Head-fovea capitis
Articular surface=elbow joint
Neck
What features are located on the distal end of the radius bone?
Trochlea-articular surface (carpus)
Styloid process-medial, attachment of medial collateral ligament of carpus
Ulnar notch
What features are located at the proximal end of the ulna?
- 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)
What features are located at the distal end of the ulna bone?
Styloid process-attachment of lateral collateral ligament of carpus
Describe the proximal articulation of the radius and ulna
- radius (head)
- radial notch of the ulna
- held by annular ligament (runs lateral to medial coronoid process, rotation possible)
Describe the distal articulation of the radius and ulna
- fibrous joint
- some rotation possible
- interosseous space between bodies, interosseous ligament and fibrous joint
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
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
What parts if the ulna and radius can you palpate?
Ulna-olecranon process, lateral styloid process
Radius- medial styloid process
How is the ulna and radius different in dogs and cats?
Cats;
- square olecranon
- radius and ulna are similar diameter
Where are the centres of ossification found on the radius and ulna bone?
Radius- proximal epiphyses,body,distal epiphyses (TOTAL=3)
Ulna-olecranon process, anconeal process, body, distal epiphyses
TOTAL=3
Describe the parts of the humerus which articulate with the ulna/radius
Trochlea- articulates with trochlear notch of the ulna and fovea capitis of the radius
Capitulum- articulates only with fovea capitis of the radius
Describe how stability of the elbow joint is maintained
COLLATERAL LIGAMENTS: humerus, radius and ulna
BONEY STRUCTURES- anconeal process (ulna) and olecranon/ulnar fossa (humerus)
Describe how movement occurs at the joint between the radius and the ulna
-limited to flexion and extension
-ulna acts as a lever
-elbow extensors insert onto he olecranon
AVULSION POSSIBLE
Describe the structure and how movement occurs at the joint between the radius and the ulna
- 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
Identify and describe the elbow extensors found at the elbow joint. What is its nerve supply?
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
Identify the elbow flexors at the elbow joint. What is their nerve supply?
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
Identify and describe the rotator muscles found at the elbow joint
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
Where would you dissect to get access to the humerus
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
Why do blood vessels cross flexor aspects of the joints?
It avoids stretching of the vessels
Where does the subclavian artery run?
Runs around the 1st rib to the axilla
Where does the axillary artery run?
Runs through the axilla
Where does the brachial artery run?
Runs down the brachium
What does the brachial artery artery branch into and where does this branch run?
Brachial artery runs into the median artery, which runs runs down the medial aspect of the antebrachium
What does the median artery run into and where do these run to?
Median artery branches into:
- Radial artery- terminates in superficial palmar branch
- Superficial brachial artery- runs down the cranial aspect of the antebrachium
Describe the palmar blood supply of a animal
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
Describe the dorsal blood supply of the forelimb
Superficial brachial artery (superficial dorsal supply to forepaw). It supples the dorsal common digital arteries and dorsal digital arteries
What happens when the blood supply reaches the digit?
Supplies fuse and then branch so that each digit has 4 vessels supplying it
Describe what is meant by the terms deep and superficial systems in the venous blood supply
Deep= follows arterial supply, VAN
Superficial system- cephalic vein, drains into the jugular vein/ vena cava
What clinical considerations would you have to have when taking a blood sample from the cephalic vein?
-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)
