Skeletal System (Bones, joints, and ligaments)

Which bones are included in the axial skeleton?

Skull, vertebral column, ribs, and sternum

Functions of axial skeleton

Support and protection and levers for muscle actions

Which bones are included in the appendicular skeleton?

Bones of thoracic and pelvic limbs

Functions of the appendicular skeleton

Serve as levers for muscle actions and locomotion

What are the regions of the thoracic limb?

Scapular region [thoracic girdle], brachium [arm], antebrachium [forearm], and manus

What are the sub-regions of the manus?

Carpus, metacarpus, and digits

What are the regions of the pelvic limb?

Rump region [Pelvic girdle], thigh, crus [leg] and pes

What are the sub-regions of the pes?

Tarsal, metatarsal, and digits

Which bones are included in the heterotopic skeleton?

Visceral bones, such as the os cordis, os penis, and auditory ossicles

What are the characteristics of long bones?

Elongated in one direction and characterized by a central shaft (diaphysis) and expanded ends (epiphyses)

Where are long bones found?

Only in the appendicular skeleton

All bones of the thoracic limb are long bones, except?

Scapula, carpal bones, and various sesamoid bones

All bones of the pelvic limb are long bones, except?

Os coxae, tarsal bones, and various sesamoid bones

Characteristics of short bones

Small, compact, and somewhat cuboidal in shape with varying number of articular surfaces

Where are short bones located?

Only appendicular skeleton

Which bones are short bones?

Carpal and tarsal bones

Characteristics of flat bones

Significantly flattened and some contain intraosseous air spaces (paranasal sinuses), which leads to them sometimes being called pneumatic bones

Where are flat bones found?

Appendicular and axial skeleton

What are the flat bones of the appendicular skeleton?

Scapula and ox coxae

What are the flat bones of the axial skeleton?

Most bones of the skull and the ribs

Characteristics of irregular bones

Irregularly shaped, often with numerous jutting processes

Where are irregular bones found?

Only the axial skeleton

What are the irregular bones?

Vertebrae, sternebrae, and skull bones that are not flat bones

Characteristics of sesamoid bones

Small "seed-like" bones typically found within muscle tendons (and occasionally ligaments) near synovial joints

Where are sesamoid bones found?

Only in the appendicular skeleton

What are the functions of sesamoid bones?

Protect tendons by reducing friction and redirecting mechanical force

What is an articulation?

Junction of two or more bones

Which joint types are the joints of stability?

Fibrous and cartilaginous

Which joints are designed for mobility?

Synovial

Characteristics of fibrous joints

Designed for little movement and united by collagenous connective tissue

What are the three types of fibrous joints?

Suture, Gomphosis, and Syndesmosis

Interdigitating joints between flat bones of the skull

Suture

Joints between the roots of teeth and the bony sockets they sit in

Gomphosis

All other fibrous joints, such as the side-to-side joints between the metacarpal bones

Syndesmosis

Characteristics of cartilaginous joints

Designed for little movement and united by cartilage

What are the two types of cartilaginous joints?

Symphysis and Synchondrosis

Uniting tissue is fibrocartilage

Symphysis

Examples of significant symphysis joints

Pelvic symphysis and mandibular symphysis

Uniting tissue is hyaline cartilage

Synchondrosis

Example of synchondrosis joint

Sacroiliac joint

Characteristics of synovial joints

Designed for movement, no direct union of bone ends, indirectly attached by joint capsule and ligaments, and adjacent bone ends covered in thin layer of cartilage for shock absorption

What type of cartilage covers the adjacent bone ends in synovial joints?

A thin layer of hyaline cartilage called articular cartilage

Sleeve-like structure that completely encloses synovial joint

Joint capsule

Space enclosed by joint capsule in synovial joint

Joint cavity

What is the fibrous membrane of the synovial joint continuous with?

Periosteum of adjacent bones

Characteristics of fibrous membrane of synovial joint

Relatively thick and composed primarily of collagenous connective tissue for strength and support of capsule; also contains elastic fibers for stretch during normal movement

What lines the interior of the fibrous membrane of the synovial joint?

Synovial membrane

Functions of synovial membrane

Continuously produce and resorb synovial fluid

Ultrafiltrate of blood plasma which contains various macromolecules, enzymes, and a few immune cells in the synovial joint

Synovial fluid

What are the important functions of the synovial fluid?

Lubricates the articular cartilage and nourishes the articular cartilage

What is continuously happening to synovial fluid?

It is being turned over in order to supply fresh fluid, which is rich in an oxygen and nutrients, and to remove wastes and debris

Connective tissue bands that join adjacent bones to one another

Ligaments

Thickenings within the fibrous membrane (ligaments) of joint capsule along the side of joint that we want very little movement

Collateral ligaments (Medial and lateral)

Which joints of flexion and extension do not possess medial and lateral collateral ligaments?

The shoulder and hip joints (more freedom of movement)

What are collateral ligaments called since they are located within the fibrous membrane and not within the joint capsule?

Extracapsular ligaments

What are ligaments located within the joint cavity called?

Intracapsular ligaments

Most proximal joint of thoracic limb between glenoid cavity of scapula and the head of the humerus

Humeral/shoulder joint

A compound joint between the humeral condyle, head of the radius, and trochlear notch of the ulna

Cubital/elbow joint

A compound joint between the distal radius & ulna, proximal row of carpal bones, distal row of carpal bones, and bases of metacarpal bones

Carpal joints

What are the three major joints that comprise the carpal joints?

Antebrachiocarpal joint, Middle carpal joint, and Carpometacarpal joint

Collective joint between the distal radius/ulna and the proximal row of carpal bones

Antebrachiocarpal joint

Collective joint between the proximal and distal rows of carpal bones

Middle carpal joint

Collective joint between the distal row of carpal bones and bases of the metacarpal bones

Carpometacarpal joint

Where does most movement occur in the carpus?

Antebrachiocarpal joint

Where does a little movement occur in the carpus?

Middle carpal joint

Where does nearly no movement occur in the carpus?

Carpometacarpal joint

Which joints of the carpus communicate?

Middle carpal joint and carpometacarpal joint

Which joint of the carpus is isolated?

If giving joint injections in the carpus, which joints would you inject?

Antebrachiocarpal joint and Middle carpal joint

Joint between head of metacarpal bone and base of proximal phalanx

Metacarpophalangeal joint

Joint between the head of proximal phalanx and base of middle phalanx

Proximal interphalangeal joint

Joint between head of middle phalanx and distal phalanx

Distal interphalangeal joint

What joints collectively make up the digital joints?

Metacarpophalangeal joint, Proximal interphalangeal joint, and Distal interphalangeal joint

What joints are in the first digit?

Metacarpophalangeal joint and interphalangeal joint

Flexor angle for humeral/shoulder joint

Caudal

Flexor angle for cubital/elbow joint

Cranial

Flexor angle for carpal joints

Palmar (caudal)

Flexor angle for digital joints

Palmar (caudal)

Most proximal joint of pelvic limb between the acetabulum of the os coxae and the head of the femur

Coxal/hip joint

Compound joint between femoral condyles, tibial condyles, and the patella

Genual/stifle joint

Compound joint between the distal tibia & fibula, proximal row of tarsal bones, central tarsal bone, distal row of tarsal bones, and bases of metatarsal bones

Tarsal joints

What are the four major joints that make up the tarsal joints?

Tarsocrural joint, Proximal intertarsal joint, Distal intertarsal joint, and Tarsometatarsal joint

Collective joint between the distal tibia/fibula and the proximal row of tarsal bones

Tarsocrural joint (also known as tibiotarsal joint)

Collective joint between the proximal row of tarsal bones (talus and calcaneus) and the central & fourth tarsal bones

Proximal intertarsal joint

Collective joint between the central tarsal bone and most of the distal row of tarsal bones (1, 2, and 3)

Distal intertarsal joint (Centodistal joint)

Collective joint between the distal row of tarsal bones and bases of the metatarsal bones

Tarsometatarsal joint

Where does most of the movement in the tarsal joints occur?

Tarsocrural joint

Which joints in the tarsal joints communicate?

1. Tarsocrural joint and proximal intertarsal joint

2. Distal intertarsal joint and tarsometatarsal joint

What is the only difference between the digital joints of the thoracic limb and pelvic limb?

Metacarpophalangeal joint in thoracic limb and metatarsophalangeal joints