ANFS 240 - Muscles & Joints

Pectoral muscle group

1-4

sternomastoid

5 red

origin: first costal cartilage and manubrium

Insertion: hyoid bone

Function: retracts the hyoid bone

sternohyoid

6 green

Origin: cranial manubrium

Insertion: hyoid bone

Function: flex the head (pair) or turn the head (singly)

pectoantebrachialis

4 blue

Origin: manubrium

Insertion: humerus (just proximal to the elbow)

Function: adduction of the forelimb

pectoralis major

3 orange

Origin: body of the sternum

Insertion: diaphysis of the humerus

Function: adduction of forelimb

pectoralis minor

2 green

Origin: body of the sternum

Insertion: ventral humerus

Function: adduction of the forelimb

xiphihumeralis

1 purple

Origin: xiphoid of the sternum

Insertion: ventral humerus

Function: adduction of the forelimb

latissimus dorsi

5

Origin: spinous processes of 4th and/or 5th thoracic and 6th lumbar vertebrae

Insertion: the medial side of the proximal humerus shaft

Function: retracts the limb, drawing the forelimb dorsocaudally. If limb is fixed, it advances the trunk forward

atlanto-occipital

condylar joint between occipital bone in the skull and atlas bone

atlanto-axial

pivot joint between atlas bone and axis bone

vertebral articulations

plane joint, small articular surfaces that are nearly flat, more of a sliding motion than a true flexion or rotation

glenohumeral

ball and socket joint, shoulder joint, head of humerus articulates with the supraglenoid cavity, capable of circumduction but prohibited due to excessive muscling

humeroradioulnar

hinger joint, elbow joint, flexion and extension only in one plane, no rotation or adduction/abduction

carpus

made up of 3 rows of joints

metacarpophalangeal

fetlock, hinge joint, between metacarpal bones and the proximal phalanges, where the proximal sesamoid bones lie, on the palmar side

proximal interphalangeal/pastern

teal, where P1 articulates with P2

distal interphalangeal joint

orange, where P2 articulates with P3, where distal sesamoids lie

pelvic symphysis

cartilaginous joint, where two pubis bones and two ischium bones meet ventrally, ossifies as animals age, before giving birth the joint will soften to allow for the neonate to fit through the pelvic canal, “amphiarthrosis”

coxofemoral

ball and socket joint, head of femur articulates with the acetabulum of the os coxae, capable of circumduction, unless there is heavy musculature (horse)

stifle joint

the knee, made up of two separate joints

femoropatellar joint

makes up stifle joint, craniodistal aspect of the femur articulates with the sesamoid patella

femorotibial joint

makes up stifle joint, distal aspect of the femur articulates with the tibia (not fibula)

tarsus/hock

compound joint of 4 distinct joints

metatarsophalangeal/fetlock joint

metatarsal articulates with the proximal phalanx (P1), where proximal sesamoid bones lie

antebrachiocarpal joint

green, between radius and proximal row of carpal bones, capable of the most flexion

middle carpal joint

blue, between the proximal and distal rows of carpal bones, moderate flexion

carpometacarpal

orange, between the distal row of carpal bones and the metatarsals, ver little motion

tarsocrural

red, between the tibia/fibula and the proximal row of tarsal bones (high motion)

proximal intertarsal

orange, between the proximal row of tarsal bones and the central/4th tarsal bones (low motion)

distal intertarsal

yellow, between the cental tarsal bone and tarsal bones I, II, and III (low motion)

tarsometatarsal

teal, between the distal row of tarsal bones and the metatarsal bone (low motion)

flexion

1, reduction in the angle between two segments of the limb

extension & alignment

2, opening of the angle between two segments of a limb, aligning those segments

overextension

3, normal extension past straight alignment, mainly seen in distal limb

abduction

carrying moving part away from the median plane

adduction

carrying the moving part towards the median plane

rotation

a moving bone turning/spinning about the axis perpendicular to the articular surface

circumduction

combination of flexion/extension and adduction/abduction, allows for an ellipsoidal or circular movement, typically ball and socket joints

synarthrosis

immovable, ex: sutures between two skull bones

amphiarthrosis

slightly movable, ex: pelvic symphysis

diarthrosis

freely movable

plane joint

one flat surface slides over another

ball and socket joint

most versatile movement, multi-axial

hinge joint

move in only one phase, one bone is cylindrical & other is shaped to receive it, elbow

pivot joint

one bone is peg-shaped & the other forms a ring around it, atlantoaxial

condylar joint

two knuckle-shaped condylar surfaces correspond with other bones’ concave surfaces

ellipsoidal joint

oval-shaped convex surface fits over a concave one

saddle joint

one convex surface articulates with a 90 degree rotated concave second surface