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SPPA 2050 Speech Anatomy and Physiology The Skeletal System For some, things do not get much drier than skeletal anatomy. The main skeletal components of the body are skull, mandible and hyoid bone, the vertebral column, the ribcage, the pelvic girdle, pectoral girdle, upper limb and lower limb. You are to learn about each of these by examining relevant figures in Netter, remembering as you go items from the following “laundry lists.” First, a few general terms that frequently come up when discussing the skeletal framework of the body. Joint: an articulation of two or skeletal structures Suture: fibrous joint where opposed surfaces are closely united. Key sutures for the purposes of this course are the sagittal, coronal, lamdoid and squamosal sutures. Foramen/Meatus: opening or passage Process/ Tubercle: projection of bone a prominence or Fossa/facet: hollow or depressed area Skull and mandible: A laundry list The skull is a composite of a number of bones. We divide the skull into the cranial skeleton and the facial skeleton. The bones of the cranial skeleton are all involved to some degree in forming the cranial vault, which protects the brain. The facial skeleton is just that – a framework for the face and mouth. In no particular order, the bones of the cranial skeleton are as follows. 1. Frontal bone: This is an unpaired bone that is located under the skin of the forehead. The coronal suture attaches it to parietal bones. Landmarks of note are the glabella, a midsagittal prominence and the supraorbital margin which bounds the orbit superiorly. 2. Parietal bone: This is a paired bone that forms the lateral surface of the skull. The coronal suture attached the parietal bone to the frontal bone and the sagittal suture attached the two parietal bones in the midline. Finally the lambdoid suture attached the parietal bones to the occipital bones. 3. Occipital bone: The occipital bone is an unpaired, bowl shaped bone that forms the dorsal caudal wall of the cranium. The lambdoid suture attaches it to the parietal bones. It can be divided into squamous and basiocciptal portions. Noteworthy structures of the occipital bone include the foramen magnum, through which the brainstem/spinal cord projects, the occipital condyles which articulate with the first cervical vertebra (atlas), and the hypoglossal canal, through which the hypoglossal nerve passes. 4. Temporal bone: The temporal bone is a paired bone that partly forms the lateral and caudal wall of the cranium. It has a number of structures that are relevant to our study of speech anatomy including the external and internal auditory meati, styloid process, mastoid process, zygomatic process, mandibular fossa, carotid canal, stylomastoid foramen, through which the facial nerve passes, and the temporomandibular joint. Finally the temporal and occipital bones bound the jugular foramen, through which the glossopharyngeal, vagus and accessory nerves pass. 5. Sphenoid bone: The sphenoid bone is an unpaired bone that is not easily palpated. It is an important bone since a number of relevant muscles attach to it. It has a body, and a pair of greater and lesser wings. On the cranial surface in the midline is the sella turcica (Turkish saddle), which houses the SPPA 2050 Speech Anatomy and Physiology pituitary gland). An important landmark on the sphenoid bone is the pterygoid process, from which projects a medial pterygoid plate and hamulus and lateral pterygoid plate. The sphenoid bone contains a number of openings. There is the superior orbital fissure which allows communication between the orbit and the cranium, the foramen rotundum, which provides passage for the maxillary portion of the trigeminal nerve, the foramen ovale, which provides passage for the mandibular branch of the trigeminal nerve, and the foramen spinosum. 6. Ethmoid bone: This is a relatively small, unpaired bone located in the region of the nasal cavity. Relevant landmarks are the cribiform plate (cribiform=perforated), the crista galli, a thick, triangular plate projecting superiorly from the cribiform plate, and the perpendicular plate projecting below to form part of the nasal septum. In no particular, order, the bones of the facial skeleton are as follows 1. Maxillary bone: This is a paired bone that dominates the face below the eyes on each side of the nose. It is the permanent seat of the upper teeth and forms about ¾ of the hard palate. The maxillary bone also forms a good portion of the floor of the nasal cavity and the roof of the oral cavity, which are important boundaries of the vocal tract. Notable landmarks are the alveolar and palatine processes, the infraorbial groove and the incisive fossa. 2. Zygomatic bone: This is a paired bone that dominates the face lateral to the eyes. The zygomatic bone articulates with the maxilla and temporal bone (below) and is an important site of attachment for many lip and jaw muscles. Noteworthy landmarks are the frontal, maxillary and temporal processes. 3. Palatine bone: This is a relatively small, paired bone that articulates with the maxilla. It makes up the dorsal (posterior) ¼ of the hard palate and lateral walls of nasal cavity. The palatine bone is “L” shaped looking ventrally or dorsally. 4. Inferior nasal concha: This paired bone projects medially from the palatine and maxillary bones. 5. Vomer bone: This unpaired bone forms a portion of the nasal septum, which separates the nasal cavity into dextral and sinistral chambers. 6. Nasal bone: This paired bone forms part of the bony skeleton of the nose medial to the orbits (eye sockets). 7. Lacrimal bone: This small, paired bone helps for the medial wall of the orbit. Mandible: The mandible is an unpaired bone that forms the bony skeleton of the lower jaw. It is the permanent site of the lower teeth and articulates with the temporal bone (temporomandibular joint). Relevant landmarks include the neck and head of the condylar process, alveolar process, mental protuberance, mental foramen, mandibular foramen, coronoid process, ramus, angle and body. Hyoid Bone: The hyoid bone is a small, horseshoe-shaped bone that is located in the neck and is associated with the larynx. It will be discussed in Chapter V. Spinal Column: A laundry list 1. There are five types of vertebrae – cervical, thoracic, lumbar, sacral, and coccygeal, and there are 7, 12, 5, 5 (but fused), and (usually) 4 (also sometimes fused) of each type. All vertebrae are “named” in the same way that spinal nerves are named, by a capital letter indicating “family” or region (e.g., C, T, etc.), and an Arabic numeral indicating rostral-to-caudal position (where 1 is always most rostral relative to other vertebrae in the same family). 2. Two cervical vertebrae, C1 and C2, have special names: atlas and axis, respectively. 3. The thoracic vertebrae provide a dorsal suspensory framework for the ribs. Cervical, SPPA 2050 Speech Anatomy and Physiology thoracic, and lumbar vertebrae provide attachment sites for muscles that may play a role in respiratory movement. The sacral vertebrae “cement” the two halves of the pelvic girdle together, in the midline, and thus, contribute to the foundation of the respiratory system. The coccygeal vertebrae -- our vestigial tails -- may well be useless. We could probably lose them, like tadpoles lose their tails, and no one would be any worse off. 4. Many vertebrae have many features in common, including: a vertebral foramen, spinous and transverse processes, a corpus or body, the pedicle, superior and inferior articular processes and facets and the costal facets. Some vertebrae have special features, including: the dorsal tubercle of C1; the dens of C2; the transverse foraminae of C1-C7; progressively larger bodies as we move caudally in the column, from cervical to lumbar; sacral crests on the dorsal surface of sacral vertebrae, instead of spinous processes; no vertebral foramen for the any of the coccygeal vertebrae. Rib Cage: A laundry list 1. There are twelve pairs of ribs in all – generally true for males and females, no matter what you might have heard to the contrary. The rostral-most seven pairs (R1R7) are usually called true ribs. Each of these connects “directly” to the sternum, on the ventral side of the body, by virtue of its own cartilage that spans the space between the end of the bony (osseous) part of the rib, and the lateral margin of the sternum. The cartilaginous extension from any rib that has one is sometimes referred to as the chondral portion of the rib. The remaining five rib pairs (R8-R12) are usually called false ribs. (Tell your eighth rib that, when you break it.) The caudal-most rib pairs (R11 and R12) float (i.e., do not attach to the sternum by cartilage, even indirectly). The three nonfloating false rib pairs (R8-R10) connect to the sternum “indirectly” by virtue of ascending cartilaginous extensions that join the cartilage belonging to R7. 2. The term costal is often used in place of the term rib. Thus, the juncture between the osseous and cartilaginous portion of each of the true ribs is sometimes called the costochondral juncture. 3. Roughly speaking, each rib articulates with a thoracic vertebra of the same number (e.g., R1 with T1, R2 with T2), on the dorsal side of the body. The head and neck of each rib “fits” along the ventral surface of the transverse process of the corresponding rib. Key landmarks are the tubercle, angle, head, neck, shaft and costal groove. These landmarks can be understood well enough by examining the figures and anatomical specimens. 4. The sternum is usually said to have three parts: manubrium, body (or corpus), and xiphoid process. R1 joins the sternum (by virtue of its cartilage) at the manubrium; R2 joins the sternum at the immobile joint between the manubrium and corpus; R3-R7 join the corpus at progressively lower levels, but above the xiphoid process. Additional landmarks include the suprasternal or jugular notch, the clavicular notches, the sternal angle, the costal notches, and the manubriosternal and xiphisternal joints. 5. The ribs and sternum provide an important part of the walls of the thorax. The ribs also provide many attachment sites for muscles we use to vary thoracic volume. Finally; we can say that the ribs provide considerable protection for crucial organs (the heart and lungs). Pelvic Girdle: A laundry list 1. There are three bony components to each (dextral or sinistral) half of the pelvic girdle: the ilium, ischium, and pubis. The two halves of the pelvic girdle are “bridged” dorsally, across the midline, by the fused sacral vertebrae. Perhaps you have heard of SPPA 2050 Speech Anatomy and Physiology the sacroiliac joint. On the ventral side, the halves are bridged by a cartilaginous “disk” joining the pubic bones. This juncture is usually referred to as the pubic symphysis. 2. Prominent landmarks associated with the pelvic girdle include: the iliac crest; the acetabulum; and the stout inguinal ligament, which spans the space between the anterior superior iliac spine, and the pubic tubercle. 3. The pelvis provides a hard floor for the trunk, and ultimately, for the respiratory system. In a way, the pelvis keeps the visceral contents of your abdomen from falling on the floor, forcing them instead against the diaphragm, when you “squeeze your middle” to expire (actively). 4. As always, with any skeletal components that concern us, the bones of the pelvis provide attachment sites for certain muscles implicated in respiration. Pectoral Girdle: A laundry list 1. There are two bony components of the pectoral girdle: the clavicle and scapula (probably known to you in your former life as the collarbone and shoulder blade). The S-shaped clavicle, on the ventral side of the body, articulates medially with the manubrium of the sternum at the sternoclavicular joint. The clavicle articulates laterally with the scapula at a distinctive landmark (on the scapula) known as the acromion. Therefore, we can divide the clavicle into a sternal end, a shaft and an acromial end. The triangularly shaped, plate-like scapula, on the dorsal side of the body, articulates only with the clavicle and no other bone. 2. Distinctive landmarks associated with the scapula include its spine, the acromion, the coracoid process, and the glenoid cavity (sometimes also referred to as a facet or fossa). 3. The bones of the pectoral girdle provide attachment sites for several muscles that many have speculated may contribute in some (usually indirect) way to inspiration and/or expiration (e.g., the sternocleidomastoid; rhomboid, serratus anterior, pectoralis major and minor, and the like). Note: The bones of the upper and lower limb are not covered in the laboratory component of the course. However, you should be able to generally identify these structures for lecture. Upper Limb: A laundry list 1. 2. 3. 4. 5. 6. humerus (arm) radius (forearm) ulna (forearm) carpal bones (wrist) metacarpal bones (hand) phalanges (fingers) Lower Limb: A laundry list 1. 2. 3. 4. 5. 6. femur (thigh) tibia (leg) fibula (leg) tarsal bones (ankle) metatarsal bones (foot) phalanges (toes)