Human Osteology (Axial and Appendicular Skeleton)
Summary
TLDRThis video revisits human anatomy, focusing on the skeleton's structure and function, essential in biological anthropology. It introduces osteology—the study of bones—and highlights its significance in understanding human evolution, locomotion, and diet. The video explains key anatomical terms and planes, covers the axial and appendicular skeleton, and provides a detailed breakdown of bones in the skull, vertebral column, ribcage, limbs, and pelvis. Additionally, it discusses the evolutionary transition from ancient hominins to modern humans, setting the stage for deeper exploration into the history of human evolution.
Takeaways
- 🦴 Osteology, the study of bones, is crucial to Biological Anthropology, including forensic work and paleoanthropology.
- 🦵 The human skeleton is understood in the anatomical position: upright, with thumbs pointing outward and palms forward.
- 📏 Anatomical planes and directions (transverse, sagittal, coronal) help orient bones in relation to each other.
- 📍 Distal and proximal describe a bone’s position in relation to the trunk; medial and lateral relate to the sagittal midline.
- 🦠 The skull consists of paired and unpaired bones held together by fibrous joints called sutures, which fully close by age two.
- 🧠 The foramen magnum, located at the base of the skull, can indicate the locomotion style (bipedal or quadrupedal) of hominins.
- 🦷 Humans have four types of teeth—incisors, canines, premolars, molars—with a 2:1:2:3 dental formula, shared with other catarrhine primates.
- 🦵 The appendicular skeleton includes the limbs and pelvis, connecting via the pectoral and pelvic girdles for movement and support.
- 🧍♂️ The human vertebral column is divided into cervical, thoracic, lumbar, sacral, and coccygeal vertebrae, with specific functions and structures.
- 🦿 As hominins evolved, changes in the skeletal structure (e.g., skull, pelvis, limb bones) reflect adaptations like bipedalism and dietary shifts.
Q & A
What is osteology, and why is it important to biological anthropology?
-Osteology is the study of bones, and it is crucial to biological anthropology because it helps in understanding skeletal remains in forensic work, paleoanthropology, and functional morphology of living primates. It provides insights into the structure and function of the human skeleton, and how bones have changed over time in relation to diet and locomotion.
How is the human skeleton divided, and what does each part include?
-The human skeleton is divided into two primary parts: the axial skeleton and the appendicular skeleton. The axial skeleton consists of the skull, ribcage, and vertebral column, while the appendicular skeleton includes the limbs and pelvis.
What are the major sutures of the skull, and what do they connect?
-The major sutures of the skull include the coronal suture, which joins the frontal bone with the parietal bone, the sagittal suture, which joins the two parietal bones, and the lambdoidal suture, which joins the parietal bone with the occipital bone.
How do anatomical planes and directions help in orienting bones in the human skeleton?
-Anatomical planes and directions orient bones by dividing the body into sections. The transverse plane divides the body into top and bottom, the sagittal plane into left and right, and the coronal plane into front and back. Terms like distal, proximal, medial, lateral, anterior, posterior, inferior, and superior refer to specific positional relationships between bones.
What are the different types of vertebrae in the vertebral column, and how are they structured?
-The vertebral column consists of cervical, thoracic, lumbar, sacral, and coccygeal vertebrae. There are seven cervical vertebrae, twelve thoracic vertebrae, five lumbar vertebrae, five fused sacral vertebrae (forming the sacrum), and three to five fused coccygeal vertebrae (the tailbone). The cervical vertebrae include the Atlas (C1) and Axis (C2), which allow head movement.
What is the foramen magnum, and what significance does it hold in determining locomotion in ancient hominins?
-The foramen magnum is the hole at the base of the skull where the spinal cord exits. Its angle and position are used to determine whether ancient hominins were bipedal or quadrupedal, providing clues about their locomotion.
What bones are involved in the human dental structure, and what is the human dental formula?
-The mandible (jaw) and maxilla house the teeth, though teeth are not considered bones. Humans, like all catarrhine primates, have a dental formula of 2:1:2:3, meaning each quadrant of the mouth contains two incisors, one canine, two premolars, and three molars.
What bones make up the pectoral girdle, and how do they function in connecting the upper limbs to the axial skeleton?
-The pectoral girdle consists of two scapulae (shoulder blades) and two clavicles (collarbones). These bones connect the upper limbs to the axial skeleton, with the scapula being highly mobile and articulating with the clavicle through the acromion process, as well as with the humerus, the bone of the upper arm.
What is the composition of the pelvis, and which bone connects the pelvis to the femur?
-The pelvis consists of two halves, each called an os coxa, composed of three fused bones: the ilium, ischium, and pubis. The femur, the largest bone in the body, connects to the pelvis through the acetabulum, the socket of the hip.
What changes in the human skeleton can we observe as we move through the evolution of hominins?
-As hominins evolved, their skeletons changed from a more basal 'ape-like' condition in the Miocene to the familiar large-brained, bipedal structure of modern humans. These changes are observed in features like cranial structure, dentition, and limb proportions, reflecting adaptations to diet, locomotion, and brain development.
Outlines
🦴 Introduction to Human Anatomy and Osteology in Anthropology
This paragraph introduces the topic of human anatomy, specifically focusing on the human skeleton and its importance in biological anthropology. It touches on osteology, the study of bones, and its significance in understanding human evolution, diet, and locomotion. Key anatomical terms and directional planes (transverse, sagittal, coronal) are explained, along with terms like distal, proximal, medial, lateral, anterior, and posterior. The human skeleton is divided into the axial skeleton (skull, ribcage, vertebral column) and the appendicular skeleton (limbs, pelvis). Detailed information about the skull bones, their sutures, and the position of the foramen magnum is provided, which helps in determining the locomotion of ancient hominins. The paragraph also covers the bones of the face, dental structures, and human teeth.
🦴 Detailed Breakdown of the Vertebral Column and Limbs
This paragraph delves into the structure of the vertebral column, highlighting the different types of vertebrae: cervical, thoracic, lumbar, sacral, and coccygeal. It explains the function of the Atlas (C1) and Axis (C2) vertebrae, which allow head movement. The distinctions between 'true', 'false', and 'floating' ribs are noted, as well as the composition of the sternum. It moves on to the appendicular skeleton, which includes the limbs and pelvis. The bones of the pectoral girdle (scapulae and clavicles), upper limbs (humerus, radius, ulna), and hands (carpals, metacarpals, phalanges) are discussed, along with the pelvic bones and lower limbs (femur, tibia, fibula). The tarsal bones of the feet are also listed. The paragraph concludes by foreshadowing how these bones change over time as hominins evolve from an ape-like condition to modern humans.
Mindmap
Keywords
💡Osteology
💡Anatomical position
💡Axial skeleton
💡Appendicular skeleton
💡Foramen magnum
💡Sagittal suture
💡Phalanges
💡Dental formula
💡Atlas and Axis
💡Pelvis
Highlights
Osteology is a critical field in Biological Anthropology, relevant for forensic work, paleoanthropology, and functional morphology of primates.
Understanding the human skeleton's structure and function helps us analyze human evolution, especially in relation to diet and locomotion.
The anatomical position of the human skeleton is upright, with thumbs pointing outward and palms forward, serving as a basis for anatomical reference.
Anatomical planes, including transverse, sagittal, and coronal, are key to orienting bones in relation to each other.
The human skeleton is divided into the axial skeleton (skull, ribcage, vertebral column) and appendicular skeleton (limbs and pelvis).
The bones of the skull are held together by sutures, which fully close by age two in humans, leaving a 'soft spot' at birth.
The foramen magnum’s angle and position in the skull indicate whether a species was bipedal or quadrupedal.
The human dental formula (2:1:2:3) reflects our evolutionary relationship with other catarrhine primates, indicating the number of each type of tooth.
The vertebral column is divided into cervical, thoracic, lumbar, sacral, and coccygeal vertebrae, each serving distinct functions in human movement and support.
The human ribs are categorized as true, false, or floating ribs based on their connection to the sternum or lack thereof.
The pectoral girdle, including the scapulae and clavicles, provides mobility for the upper limbs and is crucial for human limb movement.
The pelvis is composed of two os coxae, each consisting of three fused bones—ilium, ischium, and pubis—highlighting its importance in bipedal locomotion.
The femur, the largest bone in the body, articulates with the pelvis through the acetabulum, a key feature in bipedal movement.
In humans, the lower leg consists of the tibia and fibula, with the tibia playing a major role in weight-bearing and articulation with the femur.
As humans evolved from ape-like ancestors in the Miocene, significant changes occurred in skeletal structure, including brain size and bipedalism.
Transcripts
With some relevant information on evolution understood, let’s now review some information
regarding human anatomy, so that we can dive into the meat of this anthroplogy series. As we will be
discussing a wide variety of skeletal remains, we must recall some things about the human skeleton.
This was covered in a basic way over in the Anatomy & Physiology series, but now let’s
revisit the subject with a little more context. Osteology, the study of bones, is vitally
important to Biological Anthropology. Whether we are considering forensic work, paleoanthropology,
or the functional morphology of other living primates, knowing the nature of the human
skeleton is critical. Within the context of human evolution, we need to see how our
bones have changed over time, and how this relates to things like diet and locomotion.
Osteology generally concerns not just the structure of the skeleton, but its function as
a whole, and with consideration to each bone. The human skeleton is navigated assuming the following
anatomical position: upright with the thumbs pointing outward and the palms forward. Anatomical
planes and directions help orient bones in relation to one another. The transverse plane cuts
the skeleton into top and bottom, the sagittal plane into left and right, and the coronal plane
into front and back. Distal and proximal refer to a bone’s position or surface in the limbs with
relation to the trunk: The phalanges, or fingers, are distal to the humerus, or upper arm. Likewise,
the humerus is proximal to the phalanges. Medial and lateral refer to a bone’s position or surface
in relation to the sagittal midline of the body: The ulna, a forearm bone, is medial to the radius.
Likewise, the radius is lateral to the ulna. Anterior and posterior refer to a bone’s position
or surface in relation to the coronal plane: The sternum, or breast bone, is anterior to
the vertebral column. Likewise, the vertebral column is posterior to the sternum. Lastly,
inferior and superior refer to a bone’s position or surface as “above” and “below”: The skull
is superior to the vertebral column. Likewise, the vertebral column is inferior to the skull.
The skeleton can also be divided into two primary parts: the axial skeleton and the
appendicular skeleton. The axial skeleton contains the skull, ribcage and the vertebral column, while
the appendicular skeleton contains the limbs and pelvis. The skull contains numerous bones, some of
which are paired in two mirrored parts, and some of which are not. The bones of the skull are held
together by fibrous joints, known as the sutures of the skull. These sutures do not fully close
until age two in humans, which is why babies have a “soft spot” on their head, that is effectively
exposed brain. The largest sutures of the skull include the coronal suture, which joins the
frontal bone with the parietal bone, the sagittal suture, which joins the two parietal bones, and
the lambdoidal suture, which joins the parietal bone with the occipital bone. The bones of the
brain case thus include the non-paired frontal, occipital, sphenoid, and ethmoid bones, and the
paired parietal and temporal bones, for a total of eight cranial bones. At the base of the skull,
where the spinal cord exits, is a hole called the foramen magnum. This hole’s angle and position
can be used to determine the locomotion of ancient hominins, whether they are bipedal or quadrupedal.
The bones of the face can also be paired or unpaired. Unpaired bones include the vomer and
the mandible, or jaw, and the paired bones include the nasals, lacrimals, palatines, inferior nasal
conchae, the maxilla, and the zygomatics, or cheekbones. The mandible and maxilla
house the teeth, which are not considered to be bones but are important to know about. Humans,
like all primates, have four types of teeth that are defined by their cusping: incisors,
canines, premolars, and molars. The human dental formula is the same as all catarrhine primates:
2:1:2:3, which indicates that in each quadrant of the mouth we have two incisors,
one canine, two premolars and three molars. The most posterior molars, the wisdom teeth,
cause crowding in some humans and must be removed. The vertebral column protects the spinal cord,
which exits the skull via the foramen magnum, and is composed of several types of vertebrae:
Cervical, Thoracic, Lumbar, Sacral and Coccygeal. Within the cervical vertebrae, the Atlas (C1)
is the first and allows the head to “nod” up and down, while the Axis (C2) is second and allows the
head to “shake” left and right. There are seven cervical vertebrae, twelve thoracic vertebrae,
five lumbar vertebrae, five fused sacral vertebrae known collectively as the sacrum, and three
to five fused coccygeal vertebrae, colloquially known as the tailbone. Attaching to the thoracic
vertebrae, humans have 12 paired ribs. “True” ribs connect directly to the sternum, “False” ribs via
cartilage, and “Floating” ribs do not connect at all. The sternum is composed of three smaller
bones: The manubrium is most superior, then the body, and the xyphoid process is most inferior.
Moving on, the appendicular skeleton includes the limbs and pelvis. The appendicular skeleton is
symmetrical, so the bones on the right side of the body have a mirror counterpart on the left side.
The pectoral girdle connects the upper limbs to the axial skeleton, and is composed of two
scapulae, or shoulder blades, and two clavicles, or collarbones. The scapula in humans is highly
mobile, and articulates with the clavicle through the acromion process. Both bones also articulate
with the humerus; the bone of the upper arm. The forearm is composed of two bones: the radius and
the ulna. The proximal end of the ulna creates the olecranon, or elbow, and in anatomical position is
medial to the radius. The radius, naturally, is lateral to the ulna and articulates distally with
the carpals, or wrist bones, specifically, the scaphoid and lunate bones. From lateral to medial,
the other carpal bones include the trapezium, trapezoid, capitate, hamate, triquetrum,
and pisiform bones. The carpals articulate with the metacarpals, or palmar bones,
which articulate with the phalanges, or finger bones. A single finger bone is called a phalanx,
and there are proximal, middle, and distal phalanxes that are separated by the finger joints.
The pelvis can be separated into two halves, which are individually known as os coxae. A
single os coxa is composed of three fused bones: the ilium, or blade of the pelvis, the ischium,
and the pubis. The femur, the largest bone in the body, articulates with the pelvis by the
acetabulum, or socket of the hip. The lower leg is composed of the tibia and the fibula. The tibia,
or shin bone, articulates proximally with the femur, while the fibula articulates
with the tibia instead. The tarsals, or ankle bones, meet the tibia by way of the talus bone,
which articulates with the calcaneus, or heel bone. From medial to lateral, the remaining
tarsals include the cuneiforms and navicular, as well as the cuboid bone. The metatarsals make
up the plantar portion of the toes and they articulate with the phalanges, or toe bones.
As we move forward in this series, we will see how these bones change over time; going from a
more basal “ape-like” condition in the Miocene, to the familiar large-brained, bipedal hominins that
would eventually yield humans. So let’s continue and dive back into the history of hominins.
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