Osteology Flashcards
Sagittal plane
This plane divides the body into left and right halves. It is also known as the midsagittal plane.
Coronal plane
This plane divides the body into front and rear portions. It is also known as the frontal plane.
Transverse plane
This plane lies at right angles to the sagittal and coronal planes. It is also known as the horizontal plane.
Superior
Toward the head end of the body, e.g. your chest is superior to your hips.
Cranial (or cephalic) may be used in place of superior on occasion.
Inferior
The opposite of superior. In hominins, the term inferior refers to parts of the body that are away from the head.
For example, your shins are inferior to your thighs.
Caudal – toward the tail – may be used in place of inferior.
Anterior
Toward the front of the hominin body. Your kneecaps lie anterior to your thigh/shin.
The term ventral – toward the belly – is often used as a synonym for anterior.
Posterior
The opposite of anterior. Toward the back of the body. Your ears are posterior to your eyes.
The synonymous term dorsal may also be used.
Medial
Toward the midline. The right side of your tongue is medial to the right side of your lower jawbone.
Lateral
Away from the midline. Your arm is lateral to your chest.
Endocranial
The inner surface of the cranial vault, e.g. The brain occupies the endocranial cavity.
Ectocranial
The outer surface of the cranial vault, e.g. the sagittal crest of a male silverback gorilla is an ectocranial crest.
Proximal
This refers to the portion or end of the limb that is nearest the head.
Distal (limb)
This refers to the portion or end of the limb that is furthest from the trunk or head.
Palmar
The palm side of the hand. Fingerprints are found on the palmar surface of the fingers.
Plantar
The surface of your foot that is in contact with the ground when you stand, i.e. the sole of your foot
Dorsal
The top of the foot or the back of the hand. Your toenails are on the dorsal surface of your feet.
Aperture
An opening
Canal
A narrow tube-like passage. Also known as a duct.
Cavity
A hollow space or depression
Condyle
A rounded projection associated with mobile joints
Crest
Linear structure that surmounts the surfact of a bone or forms its border
Fissure
A cleft or slit
Foramen
A circular to ovoid hole through a bone
Fossa
General term for a hollowed out area
Fovea
A small pit
Groove
A shallow linear depression
Line
A low, linear projection. Less prominent than a ridge.
Meatus
An opening, especially the external opening of a tube
Process
A slender projecting point or strut
Ridge
A well-marked linear elevation. Less prominent than a crest.
Sinus
A cavity or (less frequently) a channel
Spine
A sharp prominence or slender process of bone
Sulcus
A trench-like structure
Torus
A swollen or bulging protrusion in the shape of a bar or strut
Trochanter
A large, roughened elevated area of bone
Tuberosity
A rounded, roughened elevation of medium size
Tubercle
A small tuberosity
Frontal bone
A large single, gently rounded bone that lies at the front of the skull.
The frontal constitutes the forehead and the anterior region of the braincase.
It also contributes to the orbital regions and to the sides of the cranium.
Parietal bones
There are two parietal bones. They form the greater part of the sides and top of the braincase.
They sit behind the frontal bone, and meet along the midsagittal plane of the skull.
Occipital bone
A large single bone that lies behind the parietal bones, and forms the back and part of the base of the braincase.
The portion of the occipital that projects posteriorly has two planes that are separated by an undulating ridge.
The upper plane, which is known as the planum occipitale, is relatively smooth.
The lower plane – the planum nuchale – is rougher and muscle scarred.
The inferior portion of the occipital contains the opening through which the spinal cord exits the skull, the foramen magnum.
Temporal bones
There are two temporal bones, one on either side of the skull.
They lie below the parietal bones and in front of the occipital bone, and thus contribute to both the walls of the brain case and to the cranial base.
The temporal bones contain the structures of the ear.
Malleus, incus, and stapes
There are two sets of these three tiny bones, which are also known as the hammer (malleus), anvil (incus) and stirrup (stapes).
These are housed in the temporal bones and form part of the hearing system.
Sphenoid bone
A large single bone that resembles a butterfly in outline.
The sphenoid lies in front of the occipital, temporal bones and the parietals, and behind the bones of the face.
Vomer bone
A small, thin, bone that occupies the midline of the nasal cavity and divides it into two.
The vomer is only visible when one looks directly into the nasal cavity.
When disarticulated the vomer can be seen to resemble the keel of a boat.
Maxillae
There are two maxillae: one on the left side of the face and one on the right.
They are the largest of the bones that make up the face. The maxillae hold the upper teeth and form most of the roof of the mouth or hard palate. They also form most of thenasal aperture and nasal floor and the floors of the orbits.
Zygomatics
There are two zygomatic bones: one on the left side of the face and one on the right. The zygomatics are also known as the malar bones or cheekbones.
The zygomatics form the prominent corners of the face. They also contribute to the orbital cavity.
Each zygomatic bone has three processes: one of these articulates with the frontal bone, another articulates with a temporal bone, and the third articulates with a maxilla.
Nasal bones
There are two nasal bones.
They are small, thick, rectangular bones that lie either side of the midline of the face and articulate with the frontal bone superiorly and the maxillae laterally. The inferior ends of the nasal bones do not articulate with any other bone. Instead, they form the upper margin of the nasal aperture.
Lacrimals
There is a lacrimal bone in each orbital cavity. The lacrimals are small, thin and fragile. They form part of the medial walls of the orbital cavities and lie anterior to the ethmoid.
Palatines
There are two palatine bones. Small and delicate, the palatines form the rear of the hard palate and part of the wall and floor of the nasal cavity.
Inferior nasal conchae
There are two of these bones. They extend horizontally along the lateral walls of the nasal cavity.
They are variable in shape, but normally their anterior and posterior ends taper to a point.
Ethmoid bone
A relatively small and fragile bone that is located between the orbits in the midline.
The ethmoid articulates with 13 bones: the frontal, sphenoid, nasals, maxillae, lacrimals, palatines, inferior nasal conchae and vomer.
Mandible
The large single bone that forms the lower jaw. The mandible comprises a horizontal ramus that houses the lower teeth and an ascending ramus that articulates with the cranium.
Hyoid bone
A small U-shaped bone that is suspended in the throat below the mandible by ligaments that attach to the underside of the skull.
The hyoid is the only bone in the human body that does not articulate with any other bone.
Pulp cavity
This is the core of the tooth. It contains a soft tissue known as pulp as well as nerves and blood vessels.
Dentine
This material forms the bulk of the tooth. The pulp chamber is surrounded by dentine.
The dentine itself is covered by enamel on most of the exposed parts of the tooth and by cementum on the part implanted in the jaw.
Enamel
A white, compact, and very hard substance that covers and protects the dentine for the upper part of the tooth
Cementum
A layer of bony tissue that covers the dentine of the part of the tooth that is set in the jaw.
Anatomical components of the primate tooth
Crown (covered by enamel), neck (cemento-enamel junction), and root (covered by cementum)
Occlusal
The surface of the tooth that comes into contact with the teeth of the opposing jaw,
i.e. the biting surface.
Labial
This is found only on the anterior teeth. It is the surface that faces the lips.
Buccal
This surface is found only on the posterior teeth. It is the surface that faces the cheek.
Lingual
The surface of the tooth that faces the tongue. In the upper jaw this side of the tooth is often referred to as the PALATAL side of the tooth.
Mesial
The surface of the tooth that lies against an adjoining tooth and faces towards the median line.
Distal (tooth)
The surface of the tooth that lies against an adjoining tooth (except in the last tooth of the row) and faces away from the medial line.
Human dental formula
2.1.2.3
Primate vs non-primate
All primates have a bony bare that encircles their eye orbits. This is called the postorbital bar.
Strepsirrhines vs haplorrhines
- Most living strepsirrhines have a tooth comb (lower incisors lie horizontally)
- Strepsirrhines lack a postorbital plate. Haplorrhines have postorbital closure.
- In strepsirrhines, the frontal bone and mandibular symphysis are unfused.
Strepsirrhines
Lemurs (Madagascar), lorises (Africa and eastern Asia) and galagos (Africa).
Small-bodied and small-brained.
Mandibular toothcomb, laterally flaring talus, grooming claw on the second digit of the foot.
Haplorrhines
Tarsiers (Southeast Asia)
Large eyes, adapted for leaping
New World monkeys (South and Central America), Old World Monkeys (sub-Saharan Africa and Asia), apes
Platyrrhines vs Catarrhines
- Plaryrrhines have 3 premolars, catarrhines have 2.
2. Platyrrhines have a zygomatic-parietal contact pattern; catarrhines have a frontal-sphenoid contact pattern.
Platyrrhines
New World monkeys (Americas)
Small to medium size
Catarrhines
Old World monkeys (Africa and Asia), and apes
Hominoids vs cercopithecoids
Apes have:
- Broader noses
- Broader palates
- Relatively larger brains
- Simple molar teeth
- Lack of a tail
- Specialisations of the trunk and upper body related to climbing
Cercopithecoids
Old World monkeys (Africa and Asia)
Humans vs other apes
- Reduced teeth, particularly canines
- No diastema
- Parabolic dental arcade
- Foramen magnum is at the base of the skull; in apes, it is more posterior
- Enlarged brain size, both in relative and absolute terms
Gibbons
These relatively small-bodied (5-11kg) primates live throughout Southeast Asia. They are the most specifically diverse and numerically successful of the ape genera.
Orangutans
Genus: Pongo
The orangutan is one of the largest living primates. Male orangutans average 78kg, while females weigh around 36kg. Orangutans are found only on the islands of Borneo and Sumatra in Southeast Asia, although at one time that had a much wider distribution throughout Southeast Asia. They are at risk of extinction.
Gorillas
Genus: Gorilla
The gorilla is the largest living primate. Males weigh up to 200kg and females 70- 90kg. They are found in small populations in tropical forest areas of sub-Saharan Africa. There are two forms of gorilla. One lives in mountainous areas; the other occupies lowland habitats.
Chimpanzees
Pan troglodytes
Chimpanzees have a broad distribution that extends across much of central Africa, from Senegal in the west to Tanzania in the east. Chimpanzees are medium to large primates. Males weigh around 50kg, and females around 35kg.
Bonobos
Pan paniscus
They are found only in central Africa south of the River Zaire. Bonobos are also less heavily built than chimpanzees, with males weighing c. 45kg and females c. 33kg
-plesio-
Primitive
-apo-
Derived
Autapomorphy
Derived and exclusive to a single taxon.
E.g. mid-facial prognathism of Neanderthals; human speech (among primates)
Symplesiomorphy
Shared and primitive.
Apomorphy
Derived traits.
Plesiomorphy
Primitive traits
Synapomorphy
Shared derived similarity.
E.g. backbone among vertebrates, bipedalism among hominins
Homology
Shared derived traits
Homoplasies
Similarities due to convergent evolution or parallelism
