Chapter 7 Flashcards
Axial skeleton
80 bones; Consists of the bones that lie around the longitudinal axis of the human body, an imaginary vertical line that runs through the body’s center of gravity from the head to the space between the feet: skull bones, auditory ossicles (ear bones), hyoid bone, ribs, sternum (breastbone), and bones of the vertebral column. The auditory ossicles are not part of either the axial or appendicular skeleton but are grouped with the axial skeleton for convenience.
Appendicular skeleton
126 bones; consists of the bones of the upper and lower limbs (extremities or appendages), plus the bones forming the girdles that connect the limbs to the axial skeleton.
Long bones
Have greater length than width, consist of a shaft and a variable number of extremities or epiphyses (ends) and are slightly curved for strength; consist mostly of compact bone tissue in their diaphyses but have considerable amounts of spongy bone tissue in their epiphyses; vary tremendously in size; eg. femur (thigh bone), tibia and fibula (leg bones), humerus (arm bone), ulna and radius (forearm bones), and phalanges (finger and toe bones).
Short bones
Are somewhat cube-shaped and are nearly equal in length and width; consist of spongy bone tissue except at the surface, which has a thin layer of compact bone tissue; eg. most carpal (wrist) bones and most tarsal (ankle) bones.
Flat bones
Are generally thin and composed of two nearly parallel plates of compact bone tissue enclosing a layer of spongy bone tissue; afford considerable protection and provide extensive areas for muscle attachment; eg. cranial bones, which protect the brain, the sternum (breastbone) and ribs, which protect organs in the thorax, and the scapulae (shoulder blades).
Irregular bones
Have complex shapes and cannot be grouped into any of the previous categories; vary in the amount of spongy and compact bone present; eg. vertebrae (backbones), hip bones, certain facial bones, and the calcaneus.
Sesamoid bones
Develop in certain tendons where there is considerable friction, tension, and physical stress, such as the palms and soles; may vary in number from person to person, are not always completely ossified, and typically measure only a few millimeters in diameter - notable exceptions are the two patellae (kneecaps), large sesamoid bones located in the quadriceps femoris tendon that are normally present in everyone; functionally, they protect tendons from excessive wear and tear, and they often change the direction of pull of a tendon, which improves the mechanical advantage at a joint.
Sutural bones
Are small bones located in sutures (joints) between certain cranial bones; their number varies greatly from person to person.
Red bone marrow is restricted to ______, ______, ______, ______.
Flat bones, irregular bones, long bones and some short bones.
Surface markings
Structural features adapted for specific functions. Most are not present at birth but develop in response to certain forces and are most prominent in the adult skeleton.
What are the two major types of surface markings?
- Depressions and openings
- Processes
Depressions and openings
Sites allowing the passage of soft tissues (such as blood vessels, nerves, ligaments, and tendons) or formation of joints.
What are the types of depressions and openings?
Fissure, foramen, fossa, sulcus, and meatus.
Fissure
Narrow slit between adjacent parts of bones through which blood vessels or nerves pass (Eg. Superior orbital fissure of sphenoid bone).
Foramen
Opening through which blood vessels, nerves, or ligaments pass (Eg. Optic foramen of sphenoid bone).
Fossa
Shallow depression (Eg. Coronoid fossa of humerus).
Sulcus
Furrow along bone surface AKA groove that accommodates blood vessel, nerve, or tendon (Eg. Intertubercular sulcus of humerus).
Meatus
Tubelike opening (Eg. External auditory meatus of temporal bone).
Processes
Projections or outgrowths on bone that form joints or attachment points for connective tissue, such as ligaments and tendons.
What are the types of processes that form joints?
Condyle, facet, head
Condyle
Large, round protuberance with a smooth articular surface at end of bone (Eg. Lateral condyle of femur).
Facet
Smooth, flat, slightly concave or convex articular surface (Eg. Superior articular facet of vertebra).
Head
Usually rounded articular projection supported on neck (constricted portion) of bone (Eg. Head of femur).
What are the types of processes that form attachment points for connective tissue?
Crest, epicondyle, line, spinous process, trochanter, tubercle, and tuberosity.
Crest
Prominent ridge or elongated projection (Eg. Iliac crest of hip bone).
Epicodyle
Typically roughened projection above condyle (Eg. Medial epicondyle of femur).
Line
Long, narrow ridge or border (less prominent than crest) (Eg. Linea aspera of femur).
Spinous process
Sharp, slender projection (Eg. Spinous process of vertebra).
Trochanter
Very large projection (Eg. Greater trochanter of femur).
Tubercle
Variably sized rounded projection (Eg. Greater tubercle of humerus).
Tuberosity
Variably sized projection that has a rough, bumpy surface (Eg. Ischial tuberosity of hip bone).
Skull
Is the bony framework of the head; contains 22 bones (not counting the bones of the middle ears) and rests on the superior end of the vertebral column (backbone).
What are the two categories that the bones of the skull are grouped into?
- Cranial bones
- Facial bones
Cranial bones
Form the cranial cavity, which encloses and protects the brain. The eight cranial bones are the frontal bone, two parietal bones, two temporal bones, the occipital bone, the sphenoid bone, and the ethmoid bone.
Facial bones
14 bones form the face: two nasal bones, two maxillae (or maxillas), two zygomatic bones, the mandible, two lacrimal bones, two palatine bones, two inferior nasal conchae, and the vomer.
What are the general features and functions of the skull?
Together, the cranial and facial bones protect and support the delicate special sense organs for vision, taste, smell, hearing, and equilibrium (balance).
Frontal bone
Forms the forehead (the anterior part of the cranium), the roofs of the orbits (eye sockets), and most of the anterior part of the cranial floor.
Frontal sinuses
Lie deep to the frontal squama; are mucous membrane-lined cavities within certain skull bones.
Parietal bone
Form the greater portion of the sides and roof of the cranial cavity. The internal surfaces of the parietal bones contain many protrusions and depressions that accommodate the blood vessels supplying the dura mater, the superficial connective tissue (meninx) covering of the brain.
Temporal bones
The paired temporal bones form the inferior lateral aspects of the cranium and part of the cranial floor.
Zygomatic process
Projects from the inferior portion of the temporal squama and articulates (forms a joint) with the temporal process of the zygomatic (cheek) bone.
Zygomatic arch
Formed by the zygomatic process of the temporal bone and the temporal process of the zygomatic bone
Mandibular fossa
A socket located on the inferior posterior surface of the zygomatic process of each temporal bone; the mandibular fossa and articular tubercle articulate with the mandible (lower jawbone) to form the temporo-mandibular joint (TMJ).
Mastoid portion
Is located posterior and inferior to the external auditory meatus, or ear canal; directs sound waves into the ear. In an adult, this portion of the bone contains several mastoid air cells that communicate with the hollow space of the middle ear. These tiny air-filled compartments are separated from the brain by thin bony partitions.
Mastoid process
Is a rounded projection of the mastoid portion of the temporal bone posterior and inferior to the external auditory meatus; is the point of attachment for several neck muscles.
Internal auditory meatus
Is the opening through which the facial (VII) nerve and vestibulocochlear (VIII) nerve pass.
Petrous portion
Is a triangular part that is located at the base of the skull between the sphenoid and occipital bones, that houses the internal ear and the middle ear, along with structures involved in hearing and equilibrium (balance).
Occipital bone
Forms the posterior part and most of the base of the cranium.
Foramen magnum
Is in the inferior part of the bone. The medulla oblongata (inferior part of the brain) connects with the spinal cord within this foramen, and the vertebral and spinal arteries also pass through it along with the accessory (XI) nerve.
Occipital codyles
Oval processes with convex surfaces on either side of the foramen magnum that articulate with depressions on the first cervical vertebra (atlas) to form the atlanto-occipital joint, which allows you to nod your head “yes.”
External occipital protuberance
The most prominent midline projection on the posterior surface of the bone just above the foramen magnum. It is the bump on the back of your head, just above your neck.
Sphenoid bone
Lies at the middle part of the base of the skull. This bone is called the keystone of the cranial floor because it articulates with all the other cranial bones, holding them together.
The ______ is a bony saddle-shaped structure on the superior surface of the body of the sphenoid. The seat of the saddle is a depression called the ______.
Sella turcica; hypophyseal fossa
Ethmoid bone
Is a delicate bone located in the anterior part of the cranial floor medial to the orbits and is spongelike in appearance. It is anterior to the sphenoid and posterior to the nasal bones. The ethmoid bone forms 1.) part of the anterior portion of the cranial floor; 2.) the medial wall of the orbits; 3.) the superior portion of the nasal septum; and 4.) most of the superior sidewalls of the nasal cavity.
Nasal bones
The paired nasal bones are small, flattened, rectangular-shaped bones that form the bridge of the nose; protect the upper entry to the nasal cavity and provide attachment for a couple of thin muscles of facial expression; the major structural portion of the nose consists of cartilage.
Lacrimal bones
The paired lacrimal bones are thin and roughly resemble a fingernail in size and shape; smallest bones of the face; are posterior and lateral to the nasal bones and form a part of the medial wall of each orbit; each contain a lacrimal fossa, a vertical tunnel formed with the maxilla, that houses the lacrimal sac, a structure that gathers tears and passes them into the nasal cavity.
Palatine bones
The two L-shaped palatine bones form the posterior portion of the hard palate, part of the floor and lateral wall of the nasal cavity, and a small portion of the floors of the orbits. The posterior portion of the hard palate is formed by the horizontal plates of the palatine bones.
Inferior nasal conchae (turbinates)
Are inferior to the middle nasal conchae of the ethmoid bone, are separate bones, not part of the ethmoid bone; form a part of the inferior lateral wall of the nasal cavity and project into the nasal cavity. All three pairs of nasal conchae (superior, middle, and inferior) increase the surface area of the nasal cavity and help swirl and filter air before it passes into the lungs. However, only the superior nasal conchae of the ethmoid bone are involved in the sense of smell.
Vomer
Is a roughly triangular bone on the floor of the nasal cavity that articulates superiorly with the perpendicular plate of the ethmoid bone and sphenoid bone and inferiorly with both the maxillae and palatine bones along the midline; forms the inferior portion of the bony nasal septum.
Maxillary sinus
Each maxilla contains a large maxillary sinus that empties into the nasal cavity.
Zygomatic bones
AKA cheekbones; form the prominences of the cheeks and part of the lateral wall and floor of each orbit. They articulate with the frontal, maxilla, sphenoid, and temporal bones.
Mandible
The mandible, or lower jawbone, is the largest, strongest facial bone. It is the only movable skull bone (other than the auditory ossicles, the small bones of the ear).
Nasal septum
Divides the nasal cavity into right and left sides; consists of bone and cartilage; has three components: the vomer, septal cartilage, and the perpendicular plate of ethmoid bone.
Orbits
Formed by 7 bones of the skull; contains the eyeball and associated structures.
Coronal suture
Unites the frontal bone and both parietal bones.
Sagittal suture
Unites the two parietal bones on the superior midline of the skull. The sagittal suture is so named because in the infant, before the bones of the skull are firmly united, the suture and the fontanels (soft spots) associated with it resemble an arrow.
Lambdoid suture
Unites the two parietal bones to the occipital bone.
Squamous sutures
2 of them; unite the parietal and temporal bones on the lateral aspects of the skull.
Paranasal sinuses
Are cavities within certain cranial and facial bones near the nasal cavity; most evident in a sagittal section of the skull; are lined with mucous membranes that are continuous with the lining of the nasal cavity; secretions produced by the mucous membranes of the paranasal sinuses drain into the lateral wall of the nasal cavity; allow the skull to increase in size without a change in the mass (weight) of the bone; increase the surface area of the nasal mucosa, thus increasing the production of mucus to help moisten and cleanse inhaled air; additionally, paranasal sinuses serve as resonating (echo) chambers within the skull that intensify and prolong sounds, thereby enhancing the quality of the voice.
Fontanels
AKA “soft spots”; mesenchyme-filled spaces between cranial bones that are present at birth.
Hyoid bone
Does not articulate with any other bone - rather, it is suspended from the styloid processes of the temporal bones by ligaments and muscles; located in the anterior neck between the mandible and larynx; supports the tongue, providing attachment sites for some tongue muscles and for muscles of the neck and pharynx; the hyoid bone and the cartilages of the larynx and trachea are often fractured during strangulation -as a result, they are carefully examined at autopsy when manual strangulation is a suspected cause of death.
Vertebral column
AKA the spine, backbone, or spinal column, makes up about 2/5 of your total height and is composed of vertebrae; consists of bone and connective tissue; the spinal cord that it surrounds and protects consists of nervous and connective tissues; in addition to enclosing and protecting the spinal cord, it supports the head and serves as a point of attachment for the ribs, pelvic girdle, and muscles of the back and upper limbs.
Cervical and lumbar curves
Are convex (bulging out).
Thoracic and sacral curves
Are concave (cupping in).
The fetus has a ______ curve throughout the length of the entire vertebral column.
Single anteriorly concave
Intervertebral discs
Are found between the bodies of adjacent vertebrae from the second cervical vertebra to the sacrum and account for about 25% of the height of the vertebral column; the superior and inferior surfaces of the disc consist of a thin plate of hyaline cartilage; the discs form strong joints, permit various movements of the vertebral column, and absorb vertical shock; under compression, they flatten and broaden.
Annulus fibrosus
An outer fibrous ring each disc has that is made of fibrocartilage.
Vertebral body
The thick, disc-shaped anterior portion, that is the weight-bearing part of a vertebra. Its superior and inferior surfaces are roughened for the attachment of cartilaginous intervertebral discs.
Vertebral foramen
Formed by the vertebral body and the vertebral arch surrounding the spinal cord.
Collectively, the vertebral foramina of all vertebrae form the ______.
Vertebral (spinal) canal
Spinous process (spine)
Projects posteriorly from the junction of the laminae.
Cervical vertebrae
Found in the neck region; the bodies of the cervical vertebrae are smaller than all other vertebrae except those that form the coccyx. Their vertebral arches, however, are larger; all cervical vertebrae have three foramina: one vertebral foramen and two transverse foramina.
Atlas (C1)
Is the first cervical vertebra inferior to the skull; is a ring of bone with anterior and posterior arches and large lateral masses; lacks a body and a spinous process.
Axis (C2)
Is the second cervical vertebra; does have a vertebral body.
Thoracic vertebrae
Are found in the chest region and articulate with the ribs; are considerably larger and stronger than cervical vertebrae. Compared to cervical vertebrae, thoracic vertebrae also have longer and larger transverse processes.
Lumbar vertebrae
Found in the lower back; are the largest and strongest of the unfused bones in the vertebral column because the amount of body weight supported by the vertebrae increases toward the inferior end of the backbone; their various projections are short and thick. The superior articular processes are directed medially instead of superiorly, and the inferior articular processes are directed laterally instead of inferiorly. The spinous processes are quadrilateral in shape, are thick and broad, and project nearly straight posteriorly. The spinous processes are well adapted for the attachment of the large back muscles.
Sacrum
Is a triangular bone formed by the union of five sacral vertebrae (S1–S5); begin to fuse in individuals between 16 and 18 years of age, a process usually completed by age 30; positioned at the posterior portion of the pelvic cavity medial to the two hip bones; serves as a strong foundation for the pelvic girdle; the female sacrum is shorter, wider, and more curved between S2 and S3 than the male sacrum.
Sacral promontory
Base of the sacrum; is one of the points used for measurements of the pelvis.
Sacroiliac joints
Formed from the auricular surface of the sacrum articulating with the ilium of each hip bone.
Coccyx
Like the sacrum, is triangular in shape; formed by the fusion of usually four coccygeal vertebrae - the coccygeal vertebrae fuse somewhat later than the sacral vertebrae, between the ages of 20 and 30; in females, the coccyx points inferiorly to allow the passage of a baby during birth; in males, it points anteriorly.
Thorax
Refers to the entire chest region.
Sternum
AKA breastbone, is a flat, narrow bone located in the center of the anterior thoracic wall that measures about 15 cm (6 in.) in length
What are the three parts of the sternum?
- Manubrium: the superior part.
- Body: the middle and largest part.
- Xiphoid process: the inferior, smallest part.
Sternal angle
Formed by the junction of the manubrium and body.
Suprasternal notch
A depression on the superior surface of the manubrium.
Clavicular notches
Lateral to the suprasternal notch.
Ribs
There are twelve pairs of ribs, numbered 1–12 from superior to inferior; give structural support to the sides of the thoracic cavity; increase in length from the first through seventh, and then decrease in length to rib 12; each rib articulates posteriorly with its corresponding thoracic vertebra.
Costal cartilage
Strip of hyaline cartilage; contribute to the elasticity of the thoracic cage and prevent various blows to the chest from fracturing the sternum and/or ribs.
