Anatomy: Axial and Appendicular Skeleton Overview

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Questions and Answers

What are the primary functions of the axial skeleton?

Provide structure and support for the spinal cord and brain (correct)

Support and protect the organs of the thorax and abdomen (correct)

Facilitate limb movement through muscle attachment

Store minerals and produce blood cells

Which bones are classified as part of the facial bones?

Frontal and occipital bones

Sphenoid and ethmoid bones

Maxilla and mandible (correct)

Parietal and temporal bones

What distinguishes a foramen from a fissure in bones?

Foramen is a type of suture; fissure is a fracture

Foramen is a bony projection; fissure is a type of articulation

Foramen allows nerves and blood vessels to pass; fissure is an elongated opening (correct)

Foramen is a narrow opening; fissure is a large cavity

Which of the following statements is true regarding cranial and facial bones?

Cranial bones protect the brain; facial bones form the structure of the face Signup and view all the answers

Where are the paranasal sinuses located, and what is their function?

Surrounding the nasal cavity, to lighten skull weight Signup and view all the answers

What is the primary function of the pectoral girdle?

To support the upper limbs and attach them to the trunk Signup and view all the answers

Which of the following describes a key difference between the sternal end and the acromial end of the clavicle?

The sternal end articulates with the sternum, while the acromial end connects to the scapula Signup and view all the answers

Which structure is commonly referred to as the shoulder blade?

Scapula Signup and view all the answers

What type of movements are characterized by the forearm's supination and pronation?

Rotational movements of the forearm Signup and view all the answers

Which bones are involved in articulating with the radius and ulna?

Humerus, radius, and ulna Signup and view all the answers

Which feature is most distinct when observing the anterior view of the skull?

Maxilla Signup and view all the answers

Which of the following is a characteristic of the superior view of the skull?

Prominent frontal bone Signup and view all the answers

What distinguishes the posterior view of the skull?

Posterior cranial fossa visibility Signup and view all the answers

Which bones are primarily associated with the lateral view of the skull?

Temporal and parietal Signup and view all the answers

In the sagittal sectional view, which part of the skull is primarily segmented?

Parietal bones Signup and view all the answers

Which view of the skull allows observation of the internal cranial base?

Inferior view Signup and view all the answers

What significant feature is mainly highlighted in the inferior view of the skull?

Foramen magnum Signup and view all the answers

Which bone is NOT typically identified in the internal view of the cranial base?

Zygomatic bone Signup and view all the answers

What three bones fuse to form the os coxae?

Ilium, ischium, and pubis Signup and view all the answers

Which anatomical structure separates the true pelvis from the false pelvis?

Pelvic brim Signup and view all the answers

Which bones articulate at the lambdoid suture?

Occipital and parietal bones Signup and view all the answers

How do male and female pelves typically differ?

Females have a rounder overall pelvic shape Signup and view all the answers

What is the primary function of the orbits?

Enclose and protect the eyes Signup and view all the answers

What is the primary role of the ischial tuberosities?

Weight bearing when sitting Signup and view all the answers

Which statement regarding the pelvic inlet is correct?

It is oval-shaped in females Signup and view all the answers

Which bones contain paranasal sinuses?

Frontal, sphenoid, maxilla, and ethmoid bones Signup and view all the answers

What structure is associated with the auditory ossicles?

Temporal bone Signup and view all the answers

As a person ages, how do the ossa coxae typically change?

Lose density and may degenerate Signup and view all the answers

What distinguishes the pelvic outlet from the pelvic inlet?

It is the inferior opening of the pelvis Signup and view all the answers

Which of the following is not one of the five types of vertebrae?

Pelvic vertebrae Signup and view all the answers

What feature is typically larger in the female pelvis compared to the male pelvis?

Pelvic inlet diameter Signup and view all the answers

Which of the following bones is located on the lateral side of the forearm in the anatomical position?

Radius Signup and view all the answers

When the forearm is in a pronated position, which statement correctly describes the orientation of the radius and ulna?

The radius crosses over the ulna at the distal end. Signup and view all the answers

What is one of the bones that may develop avascular necrosis if fractured?

Scaphoid Signup and view all the answers

Which feature of the humerus articulates directly with the radius?

Capitulum Signup and view all the answers

How many carpal bones are there in the human wrist?

8 Signup and view all the answers

Which of the following statements best describes the surgical neck of the humerus?

It is commonly fractured in shoulder injuries. Signup and view all the answers

Which statement correctly differentiates the anatomical neck from the surgical neck of the humerus?

The surgical neck is located proximal to the humeral head. Signup and view all the answers

Which of the following bones forms part of the forearm?

Radius Signup and view all the answers

Study Notes

Chapter 8 Lecture Outline

The skeletal system is organized into two divisions: axial and appendicular.
The axial skeleton includes bones along the central body axis, such as the skull, vertebral column, and thoracic cage.
The appendicular skeleton includes bones of the upper and lower limbs, and the girdles that attach them to the axial skeleton (pectoral and pelvic).
Learning objectives include comparing and contrasting the functions and composition of the axial and appendicular skeletons, becoming familiar with terminology for common bone markings.

8.1 Components of the Skeleton

The skeletal system is composed of 22 bones for the skull.
The axial skeleton is composed of bones arranged along the central body axis.
The appendicular skeleton is composed of bones that support the upper and lower limbs.

8.1a Axial and Appendicular Skeleton

The axial and appendicular skeleton are two divisions of the human skeletal system.

8.1b Bone Markings

The study of bone markings is important for learning skeletal anatomy.

8.2 Bones and Features of the Skull

Learning objectives include distinguishing between cranial and facial bones, identifying their locations, learning bone markings and features, and comparing cranial fossae.

8.2a General Anatomy of the Skull

The skull is the most complex structure in the skeleton, with 22 bones.
It's composed of cranial and facial bones.

8.2a General Anatomy of the Cranial Bones

Surround and enclose the brain.
The roof of the cranium or calvaria is composed of frontal, parietal, and parts of occipital bones.
The base of the cranium is composed of portions of ethmoid, sphenoid, occipital, and temporal bones.

8.2a General Anatomy of the Facial Bones

Form the face.

8.2a Cavities of the Skull

The cranial cavity is the largest cavity, enclosing and protecting the brain.
The orbits are eye sockets.
The nasal cavity houses the nasal passages.

8.2b Views of the Skull and Landmark Features

Landmark features and views of the skull are essential for understanding its structure.

8.2c Sutures

Sutures are immovable joints connecting cranial bones.
Coronal suture: articulates frontal and parietal bones.
Lambdoid suture: articulates parietal and occipital bones.
Sagittal suture: connects the left and right parietal bones.
Squamous suture: articulates parietal and temporal bones.

8.2d Orbital and Nasal Complexes, Paranasal Sinuses

The orbital complex encloses the eyes and eye muscles, composed of multiple bones.
The nasal complex encloses nasal cavity and paranasal sinuses.
Paranasal sinuses are air-filled chambers open to nasal cavity with mucous membranes warming and humidifying the inhaled air; these also provide voice resonance.

8.3 Bones Associated with the Skull

Learning objectives include locating and identifying auditory ossicles and describing the structure and function of the hyoid bone.

8.3.1 Auditory Ossicles

Three tiny ear bones (malleus, incus, stapes) housed within petrous part of each temporal bone.

8.3.2 Hyoid Bone

Slender, curved bone inferior to the skull, between the mandible and larynx.
Doesn't articulate with any other bone. Has a medial body with two hornlike processes (greater and lesser cornua).
Attachment sites for tongue and larynx muscles and ligaments.

8.4b Aging of the Skull

Cranial bones interconnected by dense regular CT ("soft spots" on baby's head)
Enable some flexion and body plate ease during birth.
Fontanelles (mastoid, sphenoidal, posterior, anterior) close at different times; posterior closes around 9 months, anterior closes around 15 months.

8.5 Bones of the Vertebral Column

Learning objectives include describing the functions of the vertebral column, listing the five types of vertebrae, and naming the four spinal curvatures of an adult vertebral column..

8.5a Types of Vertebrae

The vertebral column consists of 24 individual vertebrae and the fused sacrum and coccyx.
Vertebral column divided into 5 distinct regions: cervical, thoracic, lumbar, sacrum, coccyx.

8.5b Spinal Curvatures

Spinal curvatures include four types: cervical, thoracic, lumbar, and sacral curvatures.
Primary curves are present at birth, the thoracic and sacral curves.
Result in a C-shaped column.
Secondary curves appear after birth, cervical and lumbar curves..
These help shift trunk weight over legs. The curves help support body weight, provide flexibility, and appear sequentially during fetal, newborn and childhood development stages.

8.5c Vertebral Anatomy

Common vertebral features include body (weight-bearing), vertebral arch (posterior), vertebral foramen (opening for spinal cord), intervertebral foramina (openings for spinal nerves), pedicles and laminae (arch components), spinous and transverse processes.
Intervertebral discs separate vertebral bodies, composed of anulus fibrosus (outer ring) and nucleus pulposus (inner gelatinous region) acting as shock absorbers.

8.5c Vertebral Anatomy (continued)

Cervical vertebrae (7, C1-C7): have transverse foramina, the atlas (C1) lacks body and spinous process, for nodding “yes,” and axis (C2) has dens for lateral rotation shaking the head “no”.
Thoracic vertebrae (12, T1-T12): articulates with ribs. Costal facets & demifacets.
Lumbar vertebrae (5, L1-L5): largest vertebrae; thick oval bodies. Bears most body weight.
Sacrum (5 fused vertebrae, S1-S5): triangular bone forms pelvic cavity posterior wall. Completely fused by 20-30 years old.
Coccyx (4 fused coccygeal vertebrae, Co1-Co4): tailbone. Unites during puberty.
Cervical Vertebrae (C7-prominens): has longest spinous process.

8.6 Bones of the Thoracic Cage

Describes features on ribs, differentiating between true and false ribs, and detailing their connections to the sternum.
Includes the sternum, 12 pairs of ribs, and thoracic vertebrae, encloses thoracic organs.

8.6a Sternum

Sternum (breastbone), components: manubrium (most superior), body (longest), xiphoid process (tip)
Clavicular notches, sternal angle made by junctions of manubrium and body
Costal notches (first seven rib connections).

8.6b Ribs

Twelve pairs of ribs, elongated, curved, and flattened bones originate on thoracic vertebrae in the anterior wall of the thorax.
Classified as true ribs (1–7), connected individually to sternum with cartilaginous extensions, also called costal cartilages
False ribs (8–10), their costal cartilages fuse to that of rib 7; floating ribs (11–12) without sternal connection.

8.7 The Upper and Lower Limbs: A Comparison

Upper and lower limbs share features based on evolutionary history, but differ based on primary limb functions (e.g., weight-bearing).
The proximal part is supported by a "girdle" of bones, pectoral girdle for upper limb, pelvic girdle for lower limb
Each distal end with multiple bones allow greater range of motion.

8.8 The Pectoral Girdle and Its Functions

The pectoral girdle connects the upper limbs to the trunk, and consists of clavicles and scapulae.
The clavicle is an elongated S-shaped bone attaching the sternum to the scapula forming the sternoclavicular and acromioclavicular joints.
The scapula (shoulder blade) is a broad flattened bone, has borders and angles with muscle attachment sites like the spine, acromion, coracoid process.

8.9 Bones of the Upper Limb

Includes the humerus, radius, ulna, carpals, metacarpals, and phalanges.
Differentiates between supination and pronation of the forearm (e.g., palm facing forward or backward).
Describes features and articulations of each bone, including humerus, radius, and ulna.
Describes how the radius, ulna, and humerus articulate.
Identifies the carpals, metacarpals, and phalanges.

8.10 Pelvic Girdle and its Functions

Compares true and false pelves, male and female pelvic features and anatomical differences.
The pelvic girdle consists of the sacrum, coccyx and two ossa coxae.

8.10a Os Coxae

Each os coxae is composed of fused ilium, ischium, and pubis which fuse between ages 13-15.

8.10b True and False Pelves

Pelvic brim divides pelvic cavity to true and false pelves.
True pelvis is inferior and contains pelvic cavity and organs, false is superior.

8.10c Sex Differences in the Pelvis

Discusses features of ossa coxae that differ substantially between sexes.

8.11 Bones of the Lower Limb

Describes articulations, features, functions of femur, tibia and fibula, patella including their tarsals, metatarsals and phalanges.

8.11a Femur and Patella

Longest, heaviest bone in body.
Spherically shaped head articulates with acetabulum of os coxae, has a fovea capitis,
Has an elongated neck and greater & lesser trochanters, Linea aspera, and medial and lateral condyles.
Patella: large sesamoid bone in quadriceps tendon, allows smooth gliding, protects knee joint.

8.11b Tibia and Fibula

Tibia: weight-bearing tibia and fibula bones are parallel. The tibia has medial and lateral condyles with a prominent ridge (intercondylar eminence) between them.
Fibula: non-weight-bearing lateral bone, with a knob-like head & distal tip (malleolus) connected by interosseous membrane.

8.11c Tarsals, Metatarsals, and Phalanges

7 tarsal bones form ankle and proximal foot. Proximal row includes talus, calcaneus, and navicular bone; distal includes cuneiforms (three wedge-shaped) and cuboid.
5 metatarsal bones, parallel in the palm of the foot; Roman numerals identify from medial to lateral.
14 phalanges, form toes; hallux (great toe) has 2 phalanges, other toes have 3 each.

8.11d Arches of the Foot

3 arches help support body weight.
The arches are maintained by shaped bones, ligaments, and tendons.

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Test your knowledge on the axial and appendicular skeleton in this quiz. Explore the functions and classifications of bones, including cranial, facial, and key structures like the pectoral girdle. Ideal for students studying human anatomy.