Saladin/Anatomy and Physiology

Lecture Outline

Lecture Outline - Chapter 9

Chapter Nine - The Skeletal System

I. The Skull (p. 253; Figs. 9.1 - 9.4; Transps. 117-120; Table 9.1)

A. Cranial Bones (p. 256; Fig. 9.7; Transp. 123)

1. The skull (cranium) bones are locked into position with sutures. Several large cavities occur in the skull: cranial cavity, orbits, nasal cavity, buccal cavity, middle- and inner-ear cavities, and paranasal cavities. Four bones contain sinuses: frontal, sphenoid, ethmoid, and maxilla. The spinal cord connects with the brain through the foramen magnum.

2. Frontal Bone (p. 258)

a. Features of the frontal bone include: supraorbital margin, supraorbital foramen, and frontal sinus. The coronal suture marks the edge of the frontal bone.

3. Parietal Bones (p. 258)

a. The two parietal bones extend from the coronal suture to the lambdoidal suture. The sagittal suture separates the two parietal bones at the top of the skull.

4. Temporal Bones (p. 259; Fig. 9.8; Transp. 124)

a. The temporal bones form the lower lateral walls of the cranium.

b. Features of the temporal bone include: zygomatic process, zygomatic arch, mandibular fossa, external auditory meatus, styloid process, mastoid process, stylomastoid foramen, mastoid foramen, carotid canal, and jugular foramen.

5. Occipital Bone (p. 259)

a. The features of the occipital bone that lies at the posterior base of the cranium are: pharyngeal tubercle, occipital condyle, hypoglossal canal, condylar canal, external occipital protuberance, and the superior and inferior nuchal lines.

6. Sphenoid Bone (p. 260; Fig. 9.9; Transp. 125)

a. The sphenoid is a butterfly-shaped bone that lies at the anterior base of the brain. It has greater and lesser wings, the latter of which forms part of the orbit.

b. The pituitary gland lies within the sella turcica of the sphenoid.

c. Several foramina are found within the sphenoid: foramen ovale, foramen rotundum, foramen spinosum, and foramen lacerum.

d. Nasal choane or internal nares, and the sphenoidal sinus, along with the medial and lateral pterygoids can be found in the sphenoid.

7. Ethmoid Bone (p. 261; Figs. 9.10, 9.11; Transps. 126, 127)

a. The ethmoid forms the roof of the nasal cavity, and its perpendicular plate forms the superior portion of the nasal septum. Three nasal conchae (turbinate bones) are lined with mucous membrane.

b. The crista galli forms a point of attachment for the meninges, and a cribriform plate allows the passage of olfactory nerve fibers to the brain.

B. Facial Bones (p. 261)

1. Fourteen facial bones form the face.

2. Maxillae (p. 262; Fig. 9.12; Transp. 128)

a. The maxillae are the largest facial bones and form the upper jaw. Alveolar processes mark the spaces between the upper teeth; each tooth fits into an alveolus.

b. Other features of the maxillae include: infraorbital foramen, inferior orbital fissure, the hard palate, palatine processes, and incisive foramen.

3. Palatine Bones (p. 263)

a. The palatine bones form the rest of the hard palate.

4. Zygomatic Bones (p. 263)

a. The zygomatic bones form the cheeks.

5. Lacrimal Bones (p. 263; Fig. 9.12; Transp. 128)

a. The lacrimal bones form part of the medial wall of the orbit, and a lacrimal sulcus houses the lacrimal canal.

6. Nasal Bones (p. 263)

a. The small nasal bones form the bridge of the nose.

7. Inferior Nasal Concha (p. 263)

a. The inferior nasal bone is the largest of the three conchae of the skull.

8. Vomer (p. 263)

a. The vomer forms the inferior half of the nasal septum.

9. Mandible (p. 263; Fig. 9.13; Transp. 129)

a. The mandible is the strongest bone of the skull and forms the lower jaw. It supports the lower teeth and allows mastication.

b. Features of the mandible include: body, angle, ramus, mental symphysis, mental protuberance, mental foramen, condyloid process, mandibular condyle, coronoid process, mandibular notch, and mandibular foramen.

C. Bones Associated with the Skull (p. 264; Figs. 9.14, 9.15; Transp. 130)

1. Also associated with the skull are the middle-ear auditory ossicles, and the hyoid bone.

D. The Skull in Infancy and Childhood (p. 265; Fig. 9.16; Transp. 131; Table 9.2)

1. The soft spots on an infant skull are fontanels (anterior posterior, sphenoid, and mastoid) that allow the infant to pass through the birth canal, and ossify by 1-2 years after birth.

II. The Spinal Column and Thoracic Cage (p. 267)

A. General Features of the Spinal Column (p. 267; Figs. 9.17 - 9.19; Transps. 132, 133)

1. The spinal column supports the skull and trunk, protects the spinal cord, and acts as a shock absorber during movement.

2. Intervertebral discs of fibrocartilage separate most of the 33 vertebrae.

3. Infants have a single C-shaped curvature, but adults have cervical, thoracic, lumbar, and pelvic curvatures.

B. General Structure of a Vertebra (p. 268; Figs. 9.20, 9.21; Transps. 134, 135)

1. The body of each vertebra is a mass of spongy bone surrounded by compact bone, and is the weight-bearing portion.

2. Other features of a general vertebra include: vertebral foramen, vertebral canal, neural arch, pedicle, lamina, spinous process, transverse process, superior and inferior articulating processes, intervertebral foramen, and inferior and superior vertebral notches.

C. Intervertebral Discs (p. 269)

1. The intervertebral discs consist of an inner nucleus pulposus surrounded by annulus fibrosus.

D. Regional Characteristics of Vertebrae (p. 270)

1. Cervical Vertebrae (p. 270; Figs. 9.22, 9.23; Transps. 136, 137)

a. The seven cervical vertebra are unique with their bifid spinous processes and presence of transverse foramina.

b. The first cervical vertebra (C1) is the atlas that holds up the weight of the head. It has two lateral masses with superior articular facets.

c. C2, the axis, has a distinctive dens or odontoid process that serves as the pivot point for turning the head.

2. Thoracic Vertebrae (p. 272; Fig. 9.24; Transp. 138; Table 9.3)

a. The 12 thoracic vertebrae correspond to the 12 pairs of ribs attached to them.

b. The thoracic ribs have the following distinctive features: downward sloping spinous process, larger body, articular surfaces for attachment to ribs, and a costal facet on the transverse process where ribs attach.

3. Lumbar Vertebrae (p. 272)

a. The five lumbar vertebrae feature a thick, stout body, and a blunt, squarish spinous process.

b. The lumbar vertebrae are especially resistant to twisting.

4. Sacrum (p. 272; Fig. 9.25; Transp. 139)

a. The five sacral vertebrae are fused into a single bone (the sacrum) by age 26. The anterior surface forms the wall of the pelvic cavity.

b. Four pairs of pelvic foramina are found on this anterior surface.

c. On the dorsal surface, dorsal sacral foramina form openings for spinal nerves.

d. The sacrum joins with the ilium to form the strong sacroiliac joint.

5. Coccyx (p. 274; Fig. 9.25; Transp. 139)

a. The coccyx (tailbone) consists of 4 small vertebrae fused into a single triangular bone in the adult.

E. The Thoracic Cage (p. 274; Fig. 9.26; Transp. 140)

1. The thoracic cage consists of the ribs and sternum. The ribs protect both the thoracic organs and the spleen, liver, and portions of the kidneys.

2. Sternum (p. 274)

a. The sternum consists of the manubrium, body (gladiolus), and xiphoid process.

3. Ribs (p. 275; Fig. 9.27; Transp. 141; Tables 9.3, 9.4)

a. There are 12 pairs of ribs. Ribs 1-7 are true ribs, and attach directly to the sternum with their own costal cartilages. Ribs 8-10 are false ribs because they attach to the cartilage of rib 7. Ribs 11 and 12 are floating ribs and do not join the sternum.

b. Ribs 1-10 have a head, tubercle, neck, and superior and inferior articulating facets.

III. The Pectoral Girdle and Upper Extremity (p. 275; Table 9.5)

A. Pectoral Girdle (p. 275)

1. The pectoral girdle supports the arm. It consists of the clavicle and scapula.

2. Clavicle (p. 275; Fig. 9.28; Transp. 142)

a. The clavicle is a slightly S-shaped bone. Its sternal end is rounded, and its acromial end is flattened.

b. The clavicle braces the shoulder and is thicker in those who perform manual labor. It is also the most frequently broken bone.

3. Scapula (p. 276; Fig. 9.29; Transp. 143)

a. The triangular scapula has a superior, medial, and lateral border. Features include a scapular notch, subscapular fossa, spine, supraspinous fossa, infraspinous fossa, acromion, coracoid process, and glenoid cavity.

b. The scapula articulates with the clavicle and humerus.

B. Upper Extremity (p. 277)

1. The upper extremity is divided into four regions: brachium, antebrachium, carpus, and manus.

2. Humerus (p. 277; Fig. 9.30; Transp. 144)

a. The head of the humerus articulates with the glenoid cavity of the scapula. Other features include: anatomical neck, surgical neck, greater and lesser tubercles, an intertubercular groove, deltoid tuberosity, capitulum, trochlea, and lateral and medial epicondyles.

b. The humerus is the large bone of the upper arm. Where it articulates with the ulna, an olecranon fossa and coronoid fossa are found. A pit called the radial fossa articulates with the radius.

3. Radius (p. 278; Fig. 9.31; Transp. 145)

a. The proximal head of the radius articulates with the humerus and ulna. Features include: a tuberosity, styloid process, navicular and lunate facets, and an ulnar notch.

4. Ulna (p. 278; Fig. 9.31; Transp. 145)

a. The proximal ulna bears a deep C-shaped notch where it wraps around the trochlea of the humerus. The olecranon and coronoid process mark either side of the notch.

b. A styloid process can be found at the distal edge of the ulna.

5. Carpal Bones (p. 279; Fig. 9.32; Transp. 146)

a. The carpal bones form the wrist.

b. The 8 carpals are: navicular, lunate, triquetral, pisiform, trapezium, trapezoid, capitate, and hamate.

6. Metacarpal Bones (p. 279)

a. The bones of the palm are the metacarpals.

b. Each metacarpal has a base, body, and head.

7. Phalanges (p. 279)

a. The finger bones are called the phalanges.

b. There are two phalanges in the pollex (thumb) and three in each of the other fingers.

IV. The Pelvic Girdle and Lower Extremity (p. 281; Table 9.7)

A. Pelvic Girdle (p. 281; Figs. 9.33 - 9.36; Transps. 147, 148; Table 9.6)

1. The pelvic girdle supports the trunk on the legs and encloses and protects the pelvic viscera.

2. Each half of the pelvic girdle is called the os coxae; where these two join in the front is the symphysis pubis.

3. The pelvis is bowl-shaped, with greater and lesser pelves, separated by the pelvic brim.

4. The os coxae have three distinctive features: iliac crest, acetabulum, and obturator foramen.

5. The adult os coxae forms by the fusion of the ilium, ischium, and pubis. The ischial tuberosity is the nob upon which one sits. Other features include the greater sciatic notch, illiac fossa, and ischial spine.

6. Male and female pelves are shaped somewhat differently, allowing for childbirth in females.

B. Lower Extremity (p. 284)

1. The lower extremity includes the femoral region, the patella, crural region, tarsus, and pes. The lower extremity is adapted for weight-bearing and locomotion.

2. Femur (p. 284; Fig. 9.37; Transp. 149)

a. The femur is the longest and strongest bone of the body. It is the thigh bone.

b. Features of the femur include: fovea capiptis, greater and lesser trochanters, linea aspera, medial and lateral condyles, an intercondylar fossa, medial and lateral epicondyles, and a patellar surface.

3. Patella (p. 285; Fig. 9.38; Transp. 150)

a. The patella (kneecap) is a triangular bone with a broad superior base, a pointed inferior apex, and two articular facets.

4. Tibia (p. 285; Fig. 9.38; Transp. 150)

a. The tibia is the larger and stronger of the two lower leg bones, and the only one that bears weight.

b. Features of the tibia are: medial and lateral condyles, an intercondylar eminence, tibial tuberosirt, anterior crest, and medial and lateral malleoli.

5. Fibula (p. 286)

a. The fibula is thicker at its proximal end, and has an apex and styloid process.

6. The Ankle and Foot (p. 286; Figs. 9.39, 9.40; Transp. 151)

a. The tarsal bones of the ankle include the calcaneus (heel), the talus between the calcaneus and tibia, the navicular, cuboid, and three cuneiforms.

b. The metatarsals articulate with the tarsal bones on one end and the phalanges on the other. Three spingy arches can be found in this region: medial longitudinal, lateral longitudinal, and transverse arches.

c. Toes are made of phalanges, with the great toe (hallux) having two phalanges.

CHAPTER ESSAY: Skeletal Adaptations to Bipedalism (p. 289; Fig. E.1; Transp. 152)

i. Several adaptations of the human skeleton have made bipedalism possible.

ii. Adaptations include; a strong, springy arch in the foot, a non-opposable big toe (hallux) that pushes the body forward during walking, close proximity of the knees for weight-bearing, bowl-shaped pelvis to support visceral weight, size of the Gluteus maximus, S-shaped spine, inferior foramen magnum of the skull, shorter forelimbs.

V. Connective Issues (p. 291)

A. Interactions between the skeletal system and other organ systems are listed on p. 291.

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