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Skull - Cranium: continued.

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1 Skull - Cranium: continued.
6. Features of the winged sphenoid bone include the sella turcica and sphenoidal sinuses. 7. Features of the ethmoid bone include the cribriform plates, a perpendicular plate, superior and middle nasal conchae, ethmoidal sinuses, and the crista galli. The sphenoid bone is wedged between several other bones in the anterior portion of the cranium (figures 7.12 slide 36; and 7.13 slide 38). This bone helps form the base of the cranium, the sides of the skull, and the floors and sides of the orbits. Along the midline within the cranial cavity, a portion of the sphenoid bone indents to form the saddle-shaped sella turcica. The pituitary gland occupies this depression. The sphenoid bone also contains two sphenoidal sinuses (see figure 7.11 slide 34). The ethmoid bone is located in front of the sphenoid bone (see figures 7.12 slide 36; and 7.14 slide 39). It consists of two masses, one on each side of the nasal cavity, which are joined horizontally by thin cribriform plates. These plates form part of the roof of the nasal cavity (see figure 7.14 slide 39). Projecting upward into the cranial cavity between the cribriform plates is a triangular process of the ethmoid bone called the crista galli (cock’s comb). Membranes that enclose the brain attach to this process (see figures 7.14 slide 39; and 7.15 slide 41). Portions of the ethmoid bone also form sections of the cranial floor, the orbital walls, and the nasal cavity walls. A perpendicular plate projects downward in the midlines form the cribriform plates and forms most of the nasal septum (see figure 7.15 slide 41). Delicate scroll-shaped plates called the superior nasal conchae and the middle nasal conchae project inward from the lateral portions of the ethmoid bone toward the perpendicular plate (see figure 7.10 slide 33). The lateral portions of the ethmoid bone contain may small air spaces, the ethmoidal sinuses (see figure 7.11 slide 34).

2 Inferior View of the Skull
Figure 7.13

3 Floor of the Cranial Cavity, viewed from above
Figure 7.14 – floor of the cranial cavity, viewed from above. Figure 7.14

4 C. Facial Skeleton 1. The 13 immovable facial bones and mandible form the basic face and provide attachments for muscles of mastication and expression. 2. The maxillae form the upper jaw, hard palate, floor of the orbits, sides of the nasal cavity, house the upper teeth, and contain large maxillary sinuses. The facial skeleton consists of thirteen immovable bones and a movable lower jawbone. These bones form the basic shape of the face and provide attachments for muscles that move the jaw and control facial expressions. The bones of the facial skeleton are… Maxillae: the maxillae form the upper jaw (see figures 7.12 and 7.13). Portions of these bones comprise the anterior roof of the mouth (hard palate), the floors of the orbits, and the sides and floor of the nasal cavity. They also contain the sockets of the upper teeth. Inside the maxillae, lateral to the nasal cavity, are maxillary sinuses, the largest of the sinuses (see figure 7.11). During development, portions of the maxillae called palatine processes grow together and fuse along the midline to form the anterior section of the hard palate. The inferior border of each maxillary bone projects downward, forming an alveolar process (see figure 7.15). Together, these processes for a horseshoe-shaped alveolar arch (dental arch). Teeth occupy cavities in this arch (dental alveoli). Dense connective tissue binds teeth to the bony sockets.

5 Sagittal Section through the Skull
Figure 7.15 – Sagittal section through the skull Figure 7.15

6 Facial Skeleton continued
3. Palatine bones are L-shaped bones located behind the maxillae that form the floor of the nasal cavity and hard palate. 4. Zygomatic bones make up the cheekbones and join with the temporal bones to form the zygomatic arches. 5. The lacrimal bones form part of the medial walls of the orbits. 6. Nasal bones form the bridge of the nose. Palatine bones: The L-shaped palatine bones are located behind the maxillae (see figures 7.13 and 7.15). The horizontal portions form the posterior section of the hard palate and the floor of the nasal cavity. The perpendicular portions help form the lateral walls of the nasal cavity. Zygomatic bones: the zygomatic bones form the prominences of the cheeks below and to the sides of the eyes (see figure 7.12 and 7.13). These bones also help form the lateral walls and the floors of the orbits. Each bone has a temporal process, which extends posteriorly to join the zygomatic process of a temporal bone. Together, these processes form a zygomatic arch. Lacrimal bones: A lacrimal bones is a thin, scalelike structure located in the medial wall of each orbit between the ethmoid bone and the maxilla (see figures 7.10 and 7.12). Nasal bones: the nasal bones are long, thin, and nearly rectangular (see figure 7.10 and 7.12). They lie side by side and are fused at the midline, where they form the bridge of the nose.

7 Facial Skeleton: continued
7. The vomer bone makes up a portion of the nasal septum. 8. Inferior nasal conchae are fragile, scroll- shaped bones that support mucous membranes within the nasal cavity. 9. The mandible, or lower jawbone, supports the lower teeth and includes a mandibular condyle, coronoid process, and alveolar arch. Vomer bone: the thin, flat vomer bone is located along the midline within the nasal cavity (see figures 7.10 and 7.15). Posteriorly, it joins the perpendicular plate of the ethmoid bone, and together they form the nasal septum. Inferior nasal conchae: the inferior nasal conchae are fragile, scroll-shaped bones attached to the lateral walls of the nasal cavity (see figures 7.10 and 7.15). Like the superior and middle conchae, the inferior conchae support mucous membranes within the nasal cavity. Mandible: the mandible is a horizontal, horseshoe-shaped body with a flat portion projecting upward at each end (see figure 7.10 and 7.12). This projection is divided into two processes—a posterior mandibular condyle and an anterior coronoid process. The mandibular condyles articulate with the mandibular fossae of the temporal bones (see figure 7.13), whereas the coronoid processes provide attachments for muscles used in chewing. A curved bar of bone on the superior border of the mandible, the alveolar arch, contains the hollow sockets (dental alveoli) that bear the lower teeth.

8 Infantile Skull At birth skull is incompletely developed
Fibrous membranes connecting cranial bones Fontanels (soft spots) Other characteristics Figure 7.16 – Fontanels. right lateral view and superior view of the infantile skull At birth, the skull is incompletely developed, with fibrous membranes connecting the cranial bones. These membranous areas of incomplete intramembranous ossification are called fontanels or, more commonly, soft spots (see figure 7.16, slide 44). They permit some movement between the bones, so that the developing skull is partially compressible and can slightly change shape. This enables an infant’s skull to more easily pass through the birth canal. Eventually, the fontanels close as the cranial bones grow together. Other characteristics of an infantile skull include a relatively small face with a prominent forehead and large orbits. The jaw and nasal cavity are small, the sinuses are incompletely formed, and the frontal bone is in two parts. The skull bones are thin, but they are also somewhat flexible and thus are less easily fractured than adult skull bones. Figure 7.16 Fontanels

9 Vertebral Column A. Cervical Vertebrae
1. These seven bones are the smallest of the vertebrae that comprise the neck and support the head. 2. The first vertebra is the atlas, which appears as a bony ring and supports the head. 3. The second vertebra is the axis, with its tooth-like dens that pivots within the atlas. 4. Features that separate cervical vertebrae from the rest are the bifid spinous processes and transverse foramina. The vertebral column extends from the skull to the pelvis and forms the vertical axis of the skeleton. It is composed of many bony parts, called vertebrae that are separated by masses of fibrocartilage called intervertebral discs and are connected to one another by ligaments (see figure 7.17, slide 46). The vertebral column supports the head and trunk of the body. It also protects the spinal cord, which passes through a vertebral canal formed by openings in the vertebrae. Although vertebrae in different regions of the vertebral column have special characteristics, they also have features in common. A typical vertebra has a drum-shaped body (see figure 7.18, slide 47). A longitudinal row of these vertebral bodies supports the weight of the head and trunk. The intervertebral discs, which separate adjacent vertebral bodies, cushion and soften the forces from movements such as walking and jumping. Seven cervical vertebrae comprise the bony axis of the neck (see figure 7.17, slide 46). The transverse processes of these vertebrae are distinctive because they have transverse foramina, which are passageways for arteries leading to the brain (see figure 7.18a, slide 47). Also, the spinous processes of the second through the fifth cervical vertebrae are uniquely forked (bifid). These processes provide attachments for muscles. Two of the cervical vertebrae are of special interest: the atlas and the axis (see figure 7.19, slide 48). The first vertebra, or atlas, supports the head. On its superior surface are two kidney-shaped facets that articulate with the occipital condyles. The second cervical vertebra, or axis, bears a toothlike dens (odontoid process) on its body. This process projects upward and lies in the ring of the atlas. As the head is turned from side to side, the atlas pivots around the dens.

10 The curved vertebral column consists of many vertebrae separated by intervertebral discs.
Right lateral view Posterior view Figure 7.17

11 Typical vertebra Figure 7.18 Superior view of… A cervical vertebra
A thoracic vertebra A lumbar vertebra Figure 7.18

12 Figure 7.19 – Atlas and Axis Atlas and axis.
Superior view of the atlas Right lateral view and Superior view of the axis Figure 7.19 – Atlas and Axis

13 Vertebral Column: continued
B. Thoracic Vertebrae 1. Twelve thoracic vertebrae articulate with the ribs. 2. These bones are larger and stronger than the cervical vertebrae. C. Lumbar Vertebrae 1. The five massive lumbar vertebrae support the weight of the body. The twelve thoracic vertebrae are larger than the cervical vertebrae (see figure 7.17, slide 46). Each vertebra has a long, pointed spinous process, which slopes downward, and facets on the sides of its body, which articulate with a rub (see figure 7.18b, slide 47). Five lumbar vertebrae are in the small of the back (loin) (see figure slide 46) these vertebrae are adapted with larger and stronger bodies to support more weight than the vertebrae above them (see figure 7.18c, slide 47).

14 Vertebral Column: continued
D. Sacrum 1. The sacrum is a triangular structure at the base of the vertebral column made up of five vertebrae fused into one bone. 2. The spinous processes of these vertebrae fuse to form a ridge of tubercles that have dorsal sacral foramina along their sides. 3. On the ventral surface of the sacrum, four pairs of pelvic sacral foramina provide passageways for nerves and blood vessels. The sacrum is a triangular structure, composed of five fused vertebrae, that forms the base of the vertebral column (figure 7.20, slide 51). The spinous processes of these fused bones form a ridge of tubercles. To the sides of the tubercles are rows of openings, the posterior sacral foramina, through which nerves and blood vessels pass. The vertebral foramina of the sacral vertebrae form the sacral canal, which continues through the sacrum to an opening of variable size at the tip, called the sacral hiatus. On the ventral surface of the sacrum, four pairs of anterior sacral foramina provide passageways for nerves and blood vessels.

15 Vertebral Column: continued
E. Coccyx 1. The coccyx is the lowermost portion of the vertebral column and is composed of four fused vertebrae. Figure 7.20 – sacrum and coccyx. Anterior view and Posterior view The coccyx, or tailbone, is the lowest part of the vertebral column and is usually composed of four fused vertebrae (see figure 7.20, slide 51). Ligaments attach it to the margins of the sacral hiatus. Figure 7.20 Sacrum & Coccyx

16 Thoracic Cage A. The thoracic cage includes the ribs, thoracic vertebrae, sternum, and costal cartilages. B. It supports the pectoral girdle and upper limbs, functions in breathing, and protects thoracic and upper abdominal organs. The thoracic cage includes the ribs, the thoracic vertebrae, the sternum, and the costal cartilages that attach the ribs to the sternum (see figure 7.21, slide 56). These bones support the pectoral girdle and upper limbs, protect the viscera in the thoracic and upper abdominal cavities, and play a role in breathing.

17 Thoracic Cage: continued
C. Ribs 1. Normally, there are 12 pairs of ribs that attach to the thoracic vertebrae. 2. The first seven pairs of ribs are true (or vertebrosternal) ribs that join the sternum directly by their costal cartilages. 3. The remaining five pairs are false ribs: the first three pairs are vertebrochondral ribs, and the last two pairs are floating ribs. The usual number of ribs is twenty-four—one pair attached to each of the twelve thoracic vertebrae. The first seven rib pairs, true ribs (vertebrosternal ribs), join the sternum directly by their costal cartilages. The remaining five pairs are called false ribs, because their cartilages do not reach the sternum directly. Instead, the cartilages of the upper three false ribs (vertebrochondral ribs) join the cartilages of the seventh rib. The last two (or sometimes three) rib pairs are called floating ribs (vertebral ribs) because they have no cartilaginous attachments to the sternum.

18 Thoracic Cage: continued
. 4. Features of a typical rib include a shaft, costal groove, anterior (sternal) end, head, neck, and tubercle. a. The head articulates with the vertebrae; the tubercle articulates with the transverse process of the thoracic vertebrae. A typical rib has a long, slender shaft, which curves around the chest and slopes downward. On the posterior end is an enlarged head by which the rib articulates with a facet on the body of its own vertebra and with the body of the next higher vertebra. A tubercle, close to the head of the rib, articulates with the transverse process of the vertebra.

19 Thoracic Cage: continued
D. Sternum 1. The sternum (breastbone) is located along the anterior midline of the thoracic cage. 2. It consists of an upper manubrium, middle body, and lower xiphoid process. The sternum, or breastbone, is located along the midline in the anterior portion of the thoracic cage (figure 7.21, slide 56). This flat, elongated bone develops in three parts—an upper manubrium, a middle body, and a lower xiphoid process that projects downward. The manubrium articulates with the clavicles by facets on its superior border.

20 The thoracic cage includes the ribs, the thoracic vertebrae, the sternum, and the costal cartilages that attach the ribs to the sternum. Figure 7.21

21 Pectoral Girdle A. The pectoral girdle makes an incomplete ring that supports the upper limbs. B. It is made up of two scapulae and two clavicles. C. Clavicles 1. The clavicles are elongated S-shaped bones located at the base of the neck that function to brace the scapulae. The pectoral girdle, or shoulder girdle, is composed of four parts—two clavicles and two scapulae (figure 7.22, slide 58). Although the word girdle suggests a ring-shaped structure, the pectoral girdle is an incomplete ring. It is open in the back between the scapulae, and the sternum separates its bones in front. The pectoral girdle supports the upper limbs and is an attachment for several muscles that move them. The clavicles, or collar bones, are slender, rodlike bones with elongated S shapes (figure 7.22, slide 58). Located at the base of the neck, they run horizontally between the manubrium and the scapulae. The clavicles brace the freely movable scapulae, helping to hold the shoulders in place. They also provide attachments for muscles of the upper limbs, chest and back.

22 Figure 7.22 Right portion of the pectoral girdle.
The pectoral girdle, to which the upper limbs are attached, consists of a clavicle and a scapula on each side. Radiograph of the right shoulder region, anterior view, showing the pectoral girdle and proximal end of the humerus. Figure 7.22

23 Pectoral Girdle: continued
D. Scapulae 1. The scapulae are flat, triangular bones on either side of the upper back. 2. A spine divides the scapula into unequal portions. 3. The spine leads to the acromion process (articulates with clavicle) and coracoid process (provides attachments for limb and chest muscles). 4. The glenoid cavity articulates with the head of the humerus. The scapulae, or should blades, are broad, somewhat triangular bones located on either side of the upper back (see figures 7.22, slide 58; and 7.23, slide 60). A spine divides the posterior surface of each scapula into unequal portions. This spine leads to two processes—an acromion process that forms the tip of the shoulder and a coracoid process that curves anteriorly and inferiorly to the clavicle. The acromion process articulates with the clavicle and provides attachments for muscles of the upper limb and chest. The coracoid process also provides attachments for upper limb and chest muscles. Between the processes is a depression called the glenoid cavity (glenoid fossa of the scapula) that articulates with the head of the arm bone (humerus).

24 Figure 7.23 Right scapula. Posterior surface
Lateral view showing the glenoid cavity that articulates with the head of the humerus Anterior surface Figure 7.23

25 Upper Limb A. Bones of the upper limb form the framework for the arm, forearm, and hand. The bones of the upper limb form the framework of the arm, forearm, and hand. They also provide attachments for muscles, and they function in levers that move limb parts. These bones include a humerus, a radius, an ulna, carpals, metacarpals, and phalanges (see figure 7.9, slide 29).

26 Upper Limb: continued B. Humerus 1. The humerus makes up the upper arm, extending from the scapula to the elbow. 2. It articulates with the scapulae at its head, with the radius at the capitulum, and with the ulna at the trochlea. 3. Other features of the humerus include the greater and lesser tubercles, intertubercular groove, anatomical and surgical necks, deltoid tuberosity, epicondyles, coronoid fossa, and olecranon fossa. The humerus is a long bone that extends from the scapula to the elbow (figure 7.24, slide 63). At its upper end is a smooth, rounded head that fits into the glenoid cavity of the scapula. Just below the head are two processes—a greater tubercle on the lateral side and a lesser tubercle on the anterior side. These tubercles provide attachments for muscles that move the upper limb at the shoulder. Between them is a narrow furrow, the intertubercular groove. The narrow depression along the lower margin of the humerus head separates it from the tubercles and is called the anatomical neck. Just below the head and the tubercles is a tapering region called the surgical neck, so named because fractures commonly occur there. Near the middle of the bony shaft on the lateral side is a rough, V-shaped area called the deltoid tuberosity. It provides an attachment for the muscle (deltoid) that raises the upper limb horizontally to the side. At the lower end of the humerus are two smooth condyles (a lateral capitulum and a medial trochlea) that articulate with the radius on the lateral side and the ulna on the medial side. Above the condyles on either side are epicondyles, which provide attachments for muscles and ligaments of the elbow. Between the epicondyles anteriorly is a depression, the coronoid fossa, that receives a process of the ulna (coronoid process) when the elbow bends. Another depression on the posterior surface, the olecranon fossa, receives an ulnar process (olecranon process) when the upper limb straightens at the elbow.

27 Figure 7.24 Right Humerus Right humerus. Anterior surface
Posterior surface Figure Right Humerus

28 Upper Limb: continued C. Radius 1. The radius is located on the thumb side of the forearm, extending from the elbow to the wrist. 2. The flattened head of the radius pivots with the humerus. 3. Other features of the radius include the radial tuberosity and styloid process. The radius, located on the thumb side of the forearm, extends form the elbow to the wrist and crosses over the ulna when the hand is turned so that the palm faces backward (see figure 7.25, slide 66). A thick, disclike head at the upper end of the radius articulates with the humerus and a notch of the ulna (radial notch). This arrangement allows the radius to rotate. On the radial shaft just below the head is a process called the radial tuberosity. It is an attachment for a muscle (biceps brachii) that bends the upper limb at the elbow. At the distal end of the radius, a lateral styloid process provides attachments for ligaments of the wrist.

29 Upper Limb: continued D. Ulna 1. The ulna is the longer of the two bones making up the forearm and has a trochlear notch that articulates with the humerus. 2. Other features of the ulna include the olecranon process, coronoid process, radial notch, head of the ulna, and styloid process. The ulna is longer than the radius and overlaps the end of the humerus posteriorly (see figure 7.25, slide 66). At its proximal end, the ulna has a wrenchlike opening, the trochlear notch, that articulates with the humerus. Two processes on either side of this notch, the olecranon process and the coronoid process, provide attachments for muscles. At the distal end of the ulna, its knoblike head articulates laterally with a notch of the radius (ulnar notch) and with a disc of fibrocartilage inferiorly. This disc, in turn, joins a wrist bone (triquetrum). A medial styloid process at the distal end of the ulna provides attachments for wrist ligaments.

30 Figure 7.25 Right radius and ulna.
The head of the radius articulates with the radial notch of the ulna, and the head of the ulna articulates with the ulnar notch or the radius. lateral view of the proximal end of the ulna. Figure 7.25

31 2. The framework of the hand is made up of five metacarpal bones.
Upper Limb: continued E. Hand 1. The wrist of the hand is made up of eight carpal bones bound into a carpus. 2. The framework of the hand is made up of five metacarpal bones. 3. The fingers are composed of three phalanges in each finger except the thumb, which lacks the middle phalanx. The hand is made up of the wrist, palm, and fingers. The skeleton of the wrist consists of eight small carpal bones that are firmly bound in two rows of four bones each. The resulting compact mass is called a carpus. The carpus articulates with the radius and with the fibrocarilaginous disc on the ulnar side. Its distal surface articulates with the metacarpal bones (see figure 7.26, slide 67). Five metacarpal bones, one in line with each finger, form the framework of the palm or metacarpus of the hand. These bones are cylindrical, with rounded distal ends that form the knuckles of a clenched fist. They are numbered 1-5, beginning with the metacarpal of the thumb (see figure 7.26). The metacarpals articulate proximally with the carpals and distally with the phalanges. The phalanges are the finger bones. Each finger has three phalanges—a proximal, a middle, and a distal phalanx—except the thumb, which has two (it lacks a middle phalanx).

32 Figure 7.26 Right hand Posterior view Anterior view Right hand.
Figure 7.26 names the individual bones of the carpus. Anterior view Posterior view Figure Right hand

33 Pelvic Girdle A. The pelvic girdle consists of the two hip (innominate) bones and the sacrum; it supports the trunk of the body on the lower limbs. B. The pelvic girdle supports and protects the lower abdominal and pelvic organs. The pelvic girdle consists of two hip bones (coxal bones, pelvic bones, or innominate bones) which articulate with each other anteriorly and with the sacrum posteriorly. The sacrum, coccyx, and pelvic girdle together for the bowl-shaped pelvis (see figure 7.27, slide 70). The pelvic girdle supports the trunk of the body, provides attachments for the lower limbs, and protects the urinary bladder, the distal end of the large intestine, and the internal reproductive organs.

34 Pelvic girdle. The pelvic girdle is formed by two hip bones. The pelvis includes the pelvic girdle as well as the sacrum and the coccyx. Radiograph of the pelvic girdle showing the sacrum, coccyx, and proximal ends of the femurs. Figure 7.27

35 Pelvic Girdle: continued
C. Each hip bone is made up of three bones: ilium, ischium, and pubis. These bones are fused in the region of the acetabulum, the cuplike depression that articulates with the head of the femur. D. The ilium is the largest and most superior portion of the hip bone and joins the sacrum at the sacroiliac joint. Each hip bone develops from three parts—an ilium, and ischium, and a pubis (see figure 7.28, slide 73). These parts fuse in the region of a cup-shaped cavity called the acetabulum. This depression, on the lateral surface of the hip bone, receives the rounded head of the femur (thigh bone). The ilium, which is the largest and upper-most portion of the hip bone, flares outward, forming the prominence of the hip. The margin of this prominence is called the iliac crest. Posteriorly, the ilium joins the scrum at the sacroiliac joint. A projection of the ilium, the anterior superior iliac spine, can be felt lateral to the groin and provides attachments for ligaments and muscles.


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