Classifications of Bones

• Long Bones

• Short Bones

• Flat Bones

• Irregular Bones

All bones can be separated into four different types based on the shape of each individual bone, NOT on its size. These groups are:

Long bones are bones involved with large movements. They are “elongated” (greater length than width) and cylindrical with enlarged, “knob-like” ends, called epiphyses (singular epiphysis) which are mostly spongy bone covered by a thin layer of compact bone.

Long Bones

The long shaft between the epiphyses, called the diaphysis, is composed of mostly compact bone and is “hollow.”

The epiphyses are named according to their location. The epiphysis closest to the body’s center is the proximal epiphysis, while that located farthest away is the distal epiphysis.

The “hollow” center of the diaphysis, called the medullary cavity, is filled with a fatty substance called, yellow bone marrow, while the “hollow” spaces of the epiphyseal spongy bone are filled with blood making tissue called red bone marrow.

The epiphyses are covered by articular (hyaline) cartilage at the proximal and distal articulation points (joints).

Articular Cartilage

Articular Cartilage

The epiphyses are divided by templates of hyaline cartilage in the young called epiphyseal discs (growth plates) which are replaced by bone in adults.

Epiphyseal disc (growth plates-hyaline cartilage)

Articular cartilage (hyaline cartilage)

Spongy bone

Red bone marrow (contained in spongy bone)

Compact bone

Medullary cavity

Yellow bone marrow(within medullary cavity -

made from mostly fat)

Periosteum (fibrous outer“skin” of bone)

Proximal Epiphysis

Diaphysis

DistalEpiphysyis

Long Bones of the Body

• Femur (2)

Femur

Anterior View Posterior View

• Tibia (2)

Long Bones of the Body

Tibia

Anterior View Posterior View

• Fibula (2)

Long Bones of the Body

Fibula

Anterior View Posterior View

Right Leg – Anterior View

Tibia

Fibula

Lateral Medial

Right Leg – Posterior View

Fibula

Tibia

LateralMedial

A Comparison of the Tibia to the Fibula

• Metatarsals (10)

Long Bones of the Body

Metatarsals

1

23

45

Metatarsals

Naming the Metatarsals

____________ metatarsal of the _________ foot(1st, 2nd, 3rd, 4th, or 5th) (Left or Right)

Medial

Lateral

• Phalanges of the Foot (28)

Long Bones of the Body

Phalanges

1

23

45

Proximal MiddleDistal

Phalanges

Naming the Phalanges_______________ phalanx of the ___________ digit

of the _________ foot.(1st, 2nd, 3rd, 4th, or 5th)

(Left or Right)

(proximal, middle, or distal)

Medial

Lateral

**Note: The 1st digit has only proximal & distal phalanges – no middle. All other digits have three phalanges – proximal, middle, and distal.

• Humerus (2)

Long Bones of the Body

Humerus

• Radius (2)

Long Bones of the Body

Radius

• Ulna (2)

Long Bones of the Body

Ulna

A Comparison of the Radius to the Ulna

always “palm up,” palmar or supinated perspective

“Thumb”

“Pinkie”

Radius(on thumb side)

Ulna(on pinkie side)

• Metacarpals (10)

Long Bones of the Body

Metacarpals1

2 345

1

23

45

Metacarpals

Naming the Metacarpals:

____________ metacarpal of the _________ hand.

(1st, 2nd, 3rd, 4th, or 5th)

(Left or Right)

**Note: Counting for the metacarpals 1st through 5th goes from “thumb” to “pinkie.”

• Phalanges of the Hand (28)

Long Bones of the Body

Phalanges

12

45

3

1

23

45

Naming the Phalanges:

_______________ phalanx of the ___________ digit of the

_________ hand.(1st, 2nd, 3rd, 4th, or 5th)

(Left or Right)

(proximal, middle, or distal)

Proximal

Middle

Distal

**Note: The 1st digit, or thumb, has only proximal & distal phalanges – no middle.

P

P

M

D

D

P

M

D

P

M

D

Phalanges

P

M

D

1

23

45

?

_______________ phalanx of the ___________ digit of the

_________ hand.3rd Right

Middle

_______________ phalanx of the ___________ digit of the

_________ hand.5th Right

Distal

_______________ phalanx of the ___________ digit of the

_________ hand.1st Right

Proximal

?

?

There is one more long bone name. What is it?

Clavicle (2) – the collar bone

Note the “S” or sigmoid curvature to this bone

• Femur (2)• Tibia (2)• Fibula (2)• Metatarsals (10)• Phalanges of the

Foot (28)

• Humerus (2)• Radius (2)• Ulna (2)• Metacarpals (10)• Phalanges of the

Hand (28)• Clavicles (2)

Long Bones of the Body

Clavicle

• Femur (2)• Tibia (2)• Fibula (2)• Metatarsals (10)• Phalanges of the

Foot (28)

• Humerus (2)• Radius (2)• Ulna (2)• Metacarpals (10)• Phalanges of the

Hand (28)• Clavicles (2)

Long Bones of the Body

Total long bones in the body: ??90 bones

Short bones are roughly cube-shaped, or “cuboid,” meaning length, width, and height are all closer to equal, and they are associated with smaller, more complex movements.

Note the “cuboid” shape

Short Bones

Short bones have only a thin layer of compact bone surrounding a spongy bone interior and are joined by multiple articulations. This allows for increased flexibility, decreased mass, but with no sacrifice in strength.

Note the multiple articulation surfaces

per bone

Short Bones of the Body• Carpals (16) – small

bones in the base of the hand

Carpals

5

1

23

4

43

2 1

56781 = Scaphoid

3 = Triangular

2 = Lunate

4 = Pisiform

5 = Trapezium6 = Trapezoid

7 = Capitate8 = Hamate

Proximal row of carpals

supinated (palmar) view;

laterally to medially; or from below

metacarpal 1 to metacarpal 5

Distal row of carpals

supinated (palmar) view;

laterally to medially; or from below metacarpal 1 to metacarpal 5

Short Bones of the Body• Tarsals (14) – small

bones in the posterior foot

Tarsals

1 2 3 45

7654

3

2

1

Medial Lateral

1 = Calcaneus (heel bone)

3 = Navicular2 = Talus (ankle bone)

4 = Medial Cuneiform5 = Intermediate Cuneiform6 = Lateral Cuneiform7 = Cuboid

Tarsals

Dorsal view (top of foot); Rt. foot

Short Bones of the Body• Tarsals (14)

Tarsals

• Carpals (16)

Total short bones in the body: ??30 bones

Flat bones – These bones are thin, generally curved, and as their name implies, “flat.” Their structure is formed from two parallel layers of compact bones sandwiching a layer of spongy bone. This creates large, broad, flat surfaces.

Flat Bones

This allows for a large surface area for tendon attachment as well as strong, protective structures, which is why these bones tend to protect the most important internal organs.

Flat Bones of the Body• Cranial bones (4)

Flat Bones of the BodyFrontal (1)

Flat Bones of the BodyParietal (2)**

**One on each side of the head

Flat Bones of the BodyOccipital (1)

Flat Bones of the Body• Thoracic Cage bones (25)

Flat Bones of the Body

Sternum (1)

Ribs (24)

Ribs

Flat Bones of the Body• Cranial bones (4) • Thoracic Cage bones (25)

Total flat bones in the body: ??29 bones

Irregular bones do not fit into the previous categories. They consist of a thin layer of compact bone surrounding a spongy bone interior. As implied by the name, their shapes are “irregular” and complicated. The bones of the vertebral column, pelvic girdle, face, and more are irregular bones.

Irregular Bones

• Vertebral Column (26)

Irregular Bones of the Body

7 Cervical Vertebra

12 Thoracic Vertebra

5 Lumbar Vertebra

1 Sacrum

1 Coccyx

Total Vertebra = 26 bones

Vertebral Column

• Skull bones (25)

Irregular Bones of the Body

Sphenoid (1)

Temporal (2)

Zygomatic (2)

Ethmoid (1)

Lacrimal (2)

Maxilla (2)

Mandible (1)

Nasal (2)

Cranial BonesFacial Bones

Palatine Bones (2)

Vomer (1)

Inferior Nasal Conchae (2)

Hyoid Bone (1)

Ossicles of the Ears (6)

• Other (6)

Irregular Bones of the Body

Coxal Bones or Os Coxae (2)

Scapula (2)

Posterior View

Patella (2)

Total irregular bones in the body: ??57 bones

• Vertebral Column (26)• Skull bones (25)• Other (6)

Irregular Bones of the Body

Total long bones in the body: ??90 bones

Total short bones in the body: ??30 bones

Total irregular bones in the body: ??57 bones

Total flat bones in the body: ??29 bones

Total bones in the body: ??206 bones

Total Bones in the Body

• Long Bones

• Short Bones

• Flat Bones

• Irregular Bones

• Sesamoid Bones

The additional group is:

Sometimes bones are be separated into five different types based on the shape of each individual bone. The first four have already been covered.

Sesamoid bones are bones embedded in tendons. Since they act to hold the tendon further away from the joint, the angle of the tendon is increased and thus the force of the muscle is increased. Examples of sesamoid bones are the patella and the pisiform.