Appendicular Skeleton Flashcards
o Bones of the limbs
Appendicular skeleton
- Limb that has no direct, bony connection with the axial skeleton
Thoracic limb (front leg)
Attaches to the humerus
Flat, somewhat triangular bone
Forms the socket portion of the ball and socket shoulder joint
Scapula
- Prominent, longitudinal ridge on lateral surface of the scapula
Spine of scapula
o Fairly shallow, concave articular surface on scapula
- Glenoid cavity
Long bone of the upper arm (brachium)
Humerus
- Proximal end, ball portion of the ball and socket shoulder joint
Head of the humerus
- Large process at proximal end of humerus where powerful shoulder muscles attach
Tubercles
- Extends down to the distal end that forms the elbow joint with the radius and ulna
Shaft of humerus
- Distal articular surfaces of the humerus
Condyle
Medial articular surface, articulates the ulna
Trochlea
Lateral articular surface, articulates the radius
Capitulum
- Just above the condyle on the humerus, deep indentation on the back side of the humerus
Olecranon fossa
- Nonarticular “knobs” on the medial and lateral surfaces of the humerus condyle
Medial and lateral epicondyle
One of two bones of the forearm
Distal end meets at lateral side, longer than radius
o Ulna
o The ulna and radius
Antebrachium
o Forms the point of the elbow
Olecranon process
half moon shaped, concave articular surface that wraps around part of the humeral condyle to help make the elbow joint a tight, secure joint
Trochlear notch
o The distal end of the ulna
o Articulates with the carpus
- Styloid process
The main weight bearing bone of the antebrachium
Distal end meets at medial side
Has facets that articulate with the proximal end of the ulna
Meets with the distal end of the humerus
o Radius
In horses, one large metacarpal bone that supports their weight in each leg
o Cannon bone
Extend distally from the distal row of carpal bones to the proximal phalanges of the digits
Numbered from medial to lateral
o Metacarpal bones
In horses, two smaller vestigial metacarpal bones
o Splint bones
What species,
* Walk on two toes
* Have two metacarpal bones, bones III and IV, but these are fused into a single bone
Cattle
In humans, the wrist but in horses referred to as the knee
Carpus
individual bones that make up the digits
Phalanges
What species have one digit on each limb, composed of three phalanges and three sesamoid bones – named based on their position
* Digit also contains sesamoid bones
Horses
long pastern bone
Proximal phalanx
short pastern bone
Middle phalanx
Coffin bone
distal phalanx
o In horses, located behind the joint between the large metacarpal bone the proximal phalanax in the large digital flexor tendons
two proximal sesamoid bones, Fetlock joint
In horses, located deep in the hoof behind the joint between the middle and distal phalanges where the digital flexor tendon attaches to the distal phalanx
o Distal sesamoid bone – navicular bone
What species:
Third and fourth support body weight
o Second and first are vestiges (remnants of evolution)
Dewclaws
o Each digit has a proximal, middle and distal phalanx as well as two proximal sesamoid bones and one distal sesamoid bone
Cattle
- Directly connected to the axial skeleton through the sacroiliac joint
Pelvic limb (hind leg)
Has three separate bones on each side that eventually fuse into a solid structure
Pelvis
- Cartilaginous joint that joins the two halves of the pelvis ventrally
Pelvic symphysis
- The cranial most bone of the pelvis
- Forms the sacroiliac joints with the sacrum
- Smooth “wing” projects forward
Ilium
- Forms caudal part of pelvic floor
Ischium
o The main, rear projecting process of the ischium
- Ischial tuberosity
- The smallest of the three pelvic bones
- Located medially and forms the cranial portion of the pelvic floor
Pubis
- Where the three bones that make up each side of the pelvis come together at the socket portion of the ball and socket hip joint in a concave area
o Deep socket that tightly encloses the head of the femur
Acetabulum
- Two large holes on either side of the pelvic symphysis
- Primary function is to lighten the pelvis
- Only a few small blood vessels and nerves pass through
Obturator foramina
Long bone of the thigh
Femur
- Ball portion of the ball and socket hip joint on the proximal end
- Smaller and more spherical
- Normally fits very deeply and securely into the acetabulum of the pelvis
Head of femur
- Large processes opposite the head, on the proximal end of the femur
- Where hips and thigh muscles attach
Trochanters
- Joint formed at distal end of femur
- Shaft of femur is straight
- Medial and lateral condyles articulate with the condyles on the proximal end of the tibia
- Two epicondyles don’t articulate with anything
Stifle joint
- Smooth articular groove in which the patella rides
Trochlea
Largest sesamoid bone in the body
Formed in the distal tendon of the large quadriceps femoris muscle
Helps protect the tendon as it passes down over the trochlea of the femur to insert on the tibial crest
Patella (knee cap)
Two small sesamoid bones located in the gastrocnemius (calf muscle) tendons
Not present in cattle or horses
Fabellae
Main weight bearing bone of the lower pelvic limb.
Tibia (shin bone)
- Formed from the tibia with the tarsus below it
Hock
- Proximal and cranial edge of tibia
- Patellar ligament attaches here
Tibial Tuberosity
Ridge that continues distally on tibia
Tibial crest
- Palpable process at the distal articular surface of the tibia
o “Knob” on the medial side of our ankle at the distal end of our tibia
Medial malleolus
Thin but complete bone in the lower leg
Mainly serves as a muscle attachment site
Lateral side of leg
In horses and cattle, only the proximal and distal ends are present – the shaft is not
Fibula
- Lateral knob of our ankle
Lateral malleolus
ankle in humans
tarsus
Tarsal bones in four legged animals
Hock
Projects upward and backward to form the point of the hock
o Calcaneal tuberosity
Bone in heart of cattle and sheep
OS cordis
o Bones formed in soft organs
Visceral skeleton
Bone in nose of swine
OS rostri
o Junctions between bones
Joints
- Immoveable joint
- Sutures that unite most of the skull bones
- Union of the splint bones of horses with the metacarpal and metatarsal bones
Fibrous joints or synarthroses
- Slightly moveable, slight rocking movement joint
- Intervertebral joints (containing the discs) between the bodies of adjacent vertebrae
- Symphyses between the two halves of the pelvis
- Between two sides of the mandible
Cartilaginous joints or amphiarthroses
Freely moveable joint
Synovial joints or diarthroses
Lining layer of the joint capsule
Produces fluid that lubricates the joint surfaces
Synovial membrane
- Band of fibrous connective tissue that help stabilize the bones and hold the joint together
- Join bone to bone
Ligaments
o Decreases the angle between two bones
Flexion
o Increases the angle between two bones
Extension
o Movement toward the midline
Adduction
o Movement away from the midline
Abduction
o Twisting movement of a part on its own axis
Rotation
o Distal ends of an extremity moves in a circle
Circumduction
o One joint surface swivels around another
o Only movements possible are flexion and extension
o Examples: elbow joint and atlantooccipital joint between the occipital bone in the skull and the first cervical vertebra
- Hinge or Ginglymus joints
o Joint surfaces are relatively flat
o Main movements possible are flexion and extension but some abduction and adduction are also possible
o Carpus (wrist)
- Gliding or arthrodial joints or rocking joints
o One bone _____ or rotates on another
o The only movement possible is rotation
o Only one true _______ joint found in the body – between the first and second cervical vertebrae, the atlantoaxial joint
Aka the “no” joint because it allows us to shake our head no
- Pivot or trochoid joints
