Quiz 2-Winter Flashcards
Main functions of forelimb
Posture & support (quadrupedals), locomotion, manipulation, somatosensory organs
Relative to pelvic limbs, the thoracic limb is…?
- Shorter and straighter
- Connected to the trunk by fibro-muscular attachments
Which way does the forelimb rotate during development?
Dorsally
What bones/muscles makes up the pectoral girdle?
Scapula, coracoid, clavicle & serratus ventralis, pectoralis profundus
What is special about the clavicle in quadrupedal mammals?
The clavicle is reduced or absent; no bony attachment of limb to axial skeletal
What is the gleno-humeral joint?
The “shoulder” joint; ball and socket
- The head of the humerus inserts into the glenoid of scapula
What movements are associated with the shoulder joint?
- Cranially/Caudally
- Dorsally/Ventrally
- Rotation: glenoid moves cranially, the whole limb advances
What limits movement of the GH joint?
The muscles surrounding the joint restricts movement to sagittal excursions
How is the body advance cranially?
Deep pectoral muscles pull the body cranially when the limb is advanced and fixed
What is the shoulder suspension mechanism?
A muscular sling suspends the thorax. Muscles of the shoulder girdle (serratus ventralis and pectoralis profundus) suspend the body between the forelimbs.
They transmit the weight of the head, neck, and cranial part of the trunk to the forelimbs and prevent the thorax from collapsing.
What is the brachial plexus?
Intersection of ventral rami from C6-T2 (variable between species). Named nerves carry axons originating from multiple spinal cord levels.
**Neck injuries can affect the whole limb
C6 contributes to which nerve(s)?
Suprascapular
C7 contributes to which nerve(s)?
Suprascapular, musculocutaneous, axillary, radial
C8 contributes to which nerve(s)?
Axillary, radial, median, ulnar
T1 contributes to which nerve(s)?
Radial, median, ulnar
What parent artery supplies the right thoracic limb?
Right subclavian; branching from the brachiocephalic trunk
What parent artery supplies the left thoracic limb?
Left subclavian; branching from aortic arch
What does the axillary artery supply?
Scapula, axilla, proximal humerus
Brachial artery supplies?
Arm (brachium) and proximal forearm (antebrachium)
Common interosseous artery
Last branch of brachial a. (around elbow)
Median artery
Continuation of brachial a. into the antebrachium
Radial artery
Branches from median artery
Ulnar artery
branches from common interosseous artery
Branches of axillary artery
Subscapular
Thoracodorsal
Lateral thoracic
Branch of brachial artery?
Deep brachial
What joints make up the elbow?
Radio-humeral
Ulno-humeral
Proximal radio-ulnar
*All one synovial joint
Movement of the elbow
Flexion and extension along sagittal plane
Pronation/supination of ulna around radius
What prevents ab/adduction of elbow?
Medial and lateral collateral ligaments
What prevents over-extension of elbow?
Oblique ligament located on cranial aspect of limb
True or False: the annular ligament of the radius attaches to the ulna and the radius?
False: it runs from ulna to ulna in a circular shape
What allow the distal radius to rotate around the distal ulna?
Annular ligament of radius
What’s the path of the radial nerve in brachium?
Runs caudal to the brachial artery, then dives between long and medial tricep heads
Path of the median nerve in brachium
Travels on medial aspect of arm caudal to axillary/brachial aa.
Enters antebrachium over medial collateral ligament at elbow
Path of ulnar nerve in brachium
Travels next to or united with median nerve;
splits off towards olecranon to cross caudal aspect of the elbow joint
What are the major veins near the elbow/brachium?
Cephalic vein - superficial cranial in brachium
Brachial vein - deep medial side of brachium
Median cubital vein - connects deep and superficial vv. (brachial & cephalic)
Major neurovasculature of cubital fossa
Brachial a/v
Cephalic v
Median cubital v
Median n
Ulnar n
True or False: the carpus is made up of 1 row of carpal bones
False: there are 2 rows; the proximal and distal bones
Proximal row of carpal bones by species
Carnivores: Radial + intermediate, ulnar, accessory
Equine/Bovine: radial, intermediate, ulnar, accessory
*Accessory projects behind the carpus, palpable
Distal row of carpal bones by species
Carnivores: 1, 2, 3, 4 (medial to lateral)
Equine: 1 (small), 2, 3, 4
Bovine: 2 + 3, 4
*5th is never separate, either fused or suppressed
Joints of the wrist
Distal radioulnar joint
Antebrachiocarpal* - very mobile
Midcarpal* - somewhat mobile
Carpometacarpal* - somewhat mobile; allows for some ab/adduction
*Ginglymus joints: hinge joint with some lateral movement
Wrist joints - ungulates
Antebrachiocarpal joint - very mobile (90o)
Midcarpal level - somewhat mobile (45o)
Carpometacarpal level - NO movement
Deep Palmar ligament
Covers entire palmar surface of skeleton; hides the unevenness of bones
Superficial, transverse ligament (aka flexor retinaculum)
Completes the enclosure of the carpal canal; passes obliquely accessory carpal bone to the medial aspect of carpal
Distal ligaments of accessory bone
Join bone to the adjacent carpal and metacarpal bones; assist in preventing overextension
What is the purpose of retinacula?
Functions like pulleys to distribute muscle forces; keeps tendon close
Radial nerve in antebrachium
Innervates carpal and digital extensors
- Muscular branches ramify in distal brachium
- Cutaneous branch reaches dorsal surface of digits
Horse: cutaneous branch fades at carpus
Median nerve in antebrachium
Innervates most of flexor carpus/digit mm
- Enters over medial collateral ligament
- Moves caudally to pass deep to flexor carpi radialis to carpus
Ulnar nerve in antebrachium
- Branches to carpal/digital flexor mm ramify in proximal antebrachium.
- Travels down caudal antebrachium.
- Main nerve of manus; splits proximal to accessory carpal bone.
What arteries “travel” with the median nerve?
- Brachial artery (in brachium)
- Common interosseous a. just distal to elbow
- Median artery (in antebrachium)
Where/what is the carpal tunnel?
It is deep to the flexor retinaculum (palmar surface) and constrained by carpal bones. It houses the tendons of digital flexors and the median nerve.
Plantigrade
“Flat-footed”
Walks on digits, metacarpals, carpals
Digitigrade
Walks on digits (phalanges)
Unguligrade
Walks on 1 or 2 digits
Metacarpals
I - V (I is the dewclaw)
- Base is proximal, head is distal
Phalanges
3 bones for each metacarpal
- Proximal, intermediate, distal
- 3 sesamoid bones between MC & P
- Dorsal (pea), proximal x2 (banana)
- Distal phalanx has an unguicular process instead of “head” which allows for claw
Foot pads Dog vs Cat
Dog: epidermis is heavily keratinized; dermal papillae project into epidermis; hypodermis is loose CT w/ sweat glands
Cat: epidermis is not nearly as thick; dermis = CT; hypodermis = loose CT; adipose tissue; sweat glands
Main role of the muscles in the manus
Help move the foot to adjust to different surfaces