1. Anatomy and Physiology Chapter 5 – Appendicular Skeleton

2. THE APPENDICULAR SKELETON Includes the Pectoral girdle, Upper/Lower limbs, and Pelvic girdle. Bones of appendicular skeleton are adapted to carry out movements typical of active lifestyle.

3. Pectoral girdles attach upper limbs to axial skeleton and provide insertion points for many muscles that move upper limbs. They have a flexibility and mobility not seen anywhere else in body because: It has the only attachment point of the pectoral girdle to the axial skeleton at the sternoclavicular joints anteriorly. The looseness of scapula attachment allows scapula to move freely across thorax. the socket of shoulder joint (glenoid cavity) is small, shallow, poorly reinforced by ligaments. Great for flexibility, bad for stability in which shoulder displacements are very common. PECTORAL GIRDLES (Shoulder) Made up of two bones – anterior CLAVICLE, posterior SCAPULA Scapula attached to thorax and vertebral column only by muscles attached on their surfaces.

4. CLAVICLES “collarbones” Slender, doubly curved long bones extend horizontally across upper thorax. Rounded on medial STERNAL end (attaching to sternum manubrium), flattened on lateral ACROMIAL end, which articulates with acromion of scapula. Convex and concave in shape Smooth superior surface; ridged and grooved on inferior surface Attachment points for thoracic and shoulder muscles Acts as anterior braces – hold out the scapula and their appended limbs away from upper narrower portion of thorax. If fractured, the entire shoulder region collapses medially.

7. SCAPULA: “shoulder blades” Triangular shape, flat bones located dorsally on thorax between ribs 2-7. 3 borders: 1. superior border - shortest/sharpest vertebral (medial) border – parallels vertebral column axillary (lateral) border – abuts armpit with small, shallow fossa called the GLENOID CAVITY. Glenoid cavity – articulates with humerus of arm, forming unstable shoulder joint. SUPERIOR ANGLE – where superior scapular border meets medial border

8. LATERAL ANGLE – superior scapular border meets lateral border INFERIOR ANGLE – medial and lateral borders join here (important anatomical landmark) Anterior (costal) surface is concave Posterior surface bears sharp, prominent spine which ends at the acromion (which can be seen at the point of the shoulder) Acromion articulates with acromial end of clavicle, forming ACROMIOCLAVICULAR JOINT. COROCOID PROCESS ‘beaklike” projects anteriorly from superior scapular border. Helps anchor bicep muscles and bounded by SUPRASCAPULAR NOTCH (nerve passage) medially and glenoid fossa laterally.

10. 30 separate bones form the framework of EACH upper limb. Includes the Arm, Forearm, Hand. ARM Made up of humerus, forearm, carpals. HUMERUS – long bone, largest/longest bone of upper limb, articulates with scapula at shoulder and with radius/ulna (bones of forearm) at the elbow. THE UPPER LIMBS

11. Proximal End Has a smooth, hemispherical HEAD which fits into glenoid cavity of scapular in such a way allowing arm to hang freely at one’s side. ANATOMICAL NECK found immediately below head, slightly constricted. Laterally located GREATER TUBERCLE and LESSER TUBERCLE are inferior to anatomical neck and separated by INTERTUBERCULAR (or BICIPITAL) GROOVE. Tubercles serve as muscle attachment points; intertubercular groove guides a tendon of bicep muscle of arm to its attachment point at rim of glenoid cavity. SURGICAL NECK is just distal to tubercles, where the epiphysis joins the shaft. (Called “surgical neck” because of frequent fractures occurring here). SHAFT cylindrical proximally but distally it becomes triangular in cross section, and ridges appear externally. DELTOID TUBEROSITY – roughened area of shaft – is attachment site of deltoid muscle. RADIAL GROOVE runs down shaft marking course of radial nerve.

12. Distal end Has two CONDYLES: TROCHLEA – medial pully-shaped CAPITULUM – lateral ball-like which both articulate with the ulna and radius, respectively. MEDIAL EPICONDYLE and LATERAL EPICONDYLES flank these. The ulnar nerve runs behind medial epicondyle and is nicknamed “funny bone”. CORONOID FOSSA – above trochlea on anterior surface. OLECRANON FOSSA – posterior surface. These 2 depressions allow ulna to move freely when elbow is flexed and extended. A small RADIAL FOSSA, lateral to the coronoid fossa, receives head of radius when elbow is flexed.

14. FOREARM RADIUS AND ULNA are two parallel long bones. Forearm is also known as the “antibrachium”. Proximally, they articulate with humerus while distal ends form joints with wrist bones. Radius and ulna articulate with each other both proximally and distally at small RADIOULNAR JOINTS and connected along entire length by a flexible INTEROSSEOUS MEMBRANE. In anatomical position, radius lies laterally (on thumb side) and ulna medially. PRONATION is rotating hand so palm faces posteriorly. The distal end of radius crosses over ulna and the two bones form and “X”.

15. ULNA Slightly longer than radius, responsible for forming most of elbow joint with humerus. Proximal end Two processes, the OLECRANON and CORONOID PROCESSES, separated by SEMILUNAR (Trochlear) NOTCH. These two processes along with trochlea of humerus form hinge joint allowing arm to flex or extend. When arm extended, olecranon process “locks” into olecranon fossa preventing hyperextension of forearm. The posterior olecranon process is bony part of elbow that rests on table. RADIAL NOTCH – on lateral side of coronoid process, articulates with head of radius.

17. Distal end ULNAR SHAFT is triangular, ridged, narrowing as it runs distally to its smaller, knoblike HEAD. STYLOID PROCESS is medial to the head where some ligaments of wrist attach. Laterally, the head articulates with radius to form DISTAL RADIOULNAR JOINT.

18. RADIUS Triangular, marked by lengthwise ridges. Proximal End HEAD shaped like end of spool of thread, upper concavity of head articulates with capitulum of humerus. Medially, head articulates with radial fossa of ulna. RADIAL TUBEROSITY – anchors bicep muscle of arm. Distal End Radius is expanded. Contains medial ULNAR NOTCH, which articulates with ulna, and lateral STYLOID PROCESS. Radius is concave where it articulates with carpal bones of wrist. Radius is the major forearm bone contributing to wrist joint. When radius moves the hand moves with it.

19. Wrist (carpals), Palm (metacarpals), and Digits (phalanges) CARPALS 8 marble size short bones closely united by ligaments. Gliding movement, extremely flexible. Arranged in two irregular rows of four bones each. Proximal row: (lateral to medial) SCAPHOID, LUNATE, TRIQUETRAL, PISIFORM. Scaphoid and lunate articulate with distal end of radius to form wrist joint. Distal row: (lateral to medial) TRAPEZIUM, TRAPEZOID, CAPITATE, HAMATE.

20. METACARPALS (Palm) Small long bones numbered 1 – 5 from thumb to little finger. When you clench your fist, the heads of metacarpals become your knuckles. Metacarpal 1, (thumb), is shortest and most mobile. Joint between metacarpal 1 and carpals is a “saddle joint” that allows the thumb to oppose the fingers. The special mobility of thumb is what makes human hands an efficient tool for grasping and manipulating.

21. PHALANGES (Digits) Digits or fingers are numbered 1-5 beginning with the thumb or POLLEX – made up of miniature long bones called phalanges. Third finger normally longest. Each hand contains 14 phalanges. Except for thumb, each finger has 3: the DISTAL, the MIDDLE, and PROXIMAL PHALANGES. The thumb has no middle phalanx.

23. THE PELVIC GIRDLE Attached to axial skeleton and supports organs of pelvic cavity (reproductive organs, urinary bladder, part of the large intestine). Secured to some of the strongest ligaments in body, and its sockets, which articulate with thighbones. Limits movement when compared to pectoral girdle. Sockets are deep, cuplike and heavily reinforced by ligaments.

24. Pelvic girdle formed by COXAL BONES (coxa = hip), or the OSSA COXAE, commonly known as “hip bones”. Each coxal bone unites with its partner anteriorly and with the sacrum posteriorly. The deep, basinlike structure formed by the ossa coxae, together with the sacrum and coccyx, is called the PELVIS. The total weight of the upper body rests on the pelvis. Each coxal bone is large, irregulary shaped. During childhood, consists of 3 bones: ILIUM, ISCHIUM, PUBIS In adults, these bones are firmly fused and indistinguishable, but their names are retained to refer to different regions of the composite coxal bone. ACETABULUM is a deep hemispherical socket formed on the lateral surface of os coxa made up of the fusion of ilium, ischium, pubis. Acetabulum articulates with head of femur (thigh bone).

26. ILIUM Large flaring bone forming most of coxal bone. Consists of BODY, ALA Superior margin of alae is the ILIAC CREST (hands on hip). Iliac crest terminates in the blunt ANTERIOR SUPERIOR ILIAC SPINE and the sharp POSTERIOR SUPERIOR ILIAC SPINE. Below these are the ANTERIOR and POSTERIOR INFERIOR ILIAC SPINES. All are attachment points for muscles of trunk, hip, thigh. Anterior superior iliac spine is an important anatomical landmark, easily felt through skin. Posterior superior iliac spine is positioned to reveal a skin dimple in the sacral region. Below posterior inferior iliac spine is the GREATER SCIATIC NOTCH.

27. The iliac ala is slightly concave, referring to the ILIAC FOSSA. The AURICULAR SURFACE articulates with the sacrum forming the SACROILIAC JOINT. Running down from the auricular surface is a ridge called the ILIOPECTINEAL or ARCUATE LINE. The posterolateral surface of illium, the GLUTEAL SURFACE is crossed by 3 ridges POSTERIOR, ANTERIOR, INFERIOR GLUTEAL LINES to which the hip muscles are attached.

30. ISCHIUM Arc-shaped, possesses upper thicker BODY adjoining the ilium and a thinner RAMUS that joins the pubic bone anteriorly. Three important markings: ISCHIAL SPINE, LESSER SCIATIC NOTCH, ISCHIAL TUBEROSITY. When we sit, our weight is borne entirely by the ischial tuberosities, which are the strongest parts of the hipbones. PUBIS Pubic bone forms anterior portion of ossa coxae. V-shaped with two RAMI The bladder rests upon it.The body of pubis lies medially and its anterior border is thickened to form a PUBIC CREST. The PUBIC TUBERCLE is the main pelvic attachment for the inguinal ligament. The OBTURATOR FORAMEN is a large opening formed by the rami of pubic bone with body and ramus of ischium. Large blood vessels and nerves pass through here. The SYMPHYSIS PUBIS JOINT is made by the bodies of the two pubic bones and a fibrocartilage disc. PUBIC ARCH is an inverted V-shaped arch that helps to differentiate the male and female pelvis.

31. FEMALE Modified for childbearing, Wider, shallower, lighter, rounder than male pelvis. Bone thinner, lighter, smoother. Tilted forward, cavity of true pelvis broad, shallow, more capacity. The acetabula is smaller, farther apart. Pubic angle or arch is broader and more rounded. The sacrum is wider, shorter, flatter, sacral curvature is accentuated. Coccyx is more movable, straighter. Pelvic inlet is wider, oval from side to side Pelvic outlet is wider. Ischial tuberosities shorter, farther apart and everted. COMPARISON OF FEMALE AND MALE PELVIS MALE Tilted backward, adapted for support of strong body, true pelvis cavity is narrow and deep. Bones are thicker, heavier, and markings are more prominent. Acetabula is larger, closer together. The pubic angle is more acute (less than 900). Sacrum narrow, longer, sacral promontory more ventral. Coccyx less movable; curves ventrally. Pelvic inlet narrow, heart shaped. Pelvic outlet narrower. Ischial tuberosities longer, shaper, and point more medially.

33. Lower limbs carry entire weight of erect body and are subjected to exceptional forces when we jump or run. Bones of lower limbs thicker, stronger than upper limbs. The lower limb bones are specialized for stability and weight bearing. Made up of the THIGH, LEG, FOOT. LOWER LIMBS THIGH The FEMUR (single thigh bone) is the largest, longest, strongest bone in the body. Stress on femur can reach 2 tons per square inch. Length is about ¼ of person’s height. The femur shaft is smooth and rounded. Proximally, femur articulates with hip bone and then courses medially toward its articulation point with the leg bones at the knee. This arrangement allows the knee joints to be closer to the body’s center of gravity and provides for better balance. The medial course of the two femurs is more pronounced in women due to wider pelvis.

34. FOVEA CAPITIS is the found on the ball-like HEAD of the femur. A short ligament, LIGAMENTUM TERES, runs from this pit to the acetabulum, where it helps secure the femur. Short NECK below head of femur. It is the weakest part of the femur. Junction of head and neck are the lateral GREATER TROCHANTER and medial LESSER TROCHANTER. Which are sites for thigh and buttock muscle attachment. These two trochanters are connected by the INTERTROCHANTERIC LINE (anteriorly) and the INTERTROCHANTERIC CREST (posteriorly). Just below greater trochanter (posteriorly) is the GLUTEAL TUBEROSITY, which blends into a ridge, the LINEA ASPERA, distally; both markings are sites of muscle attachment. Distally, femur shaft broadens and terminates in the LATERAL and MEDIAL CONDYLES. They articulate with tibia. The PATELLAR SURFACE between the condyles on the anterior femur surface articulates with the PATELLA (knee cap). PATELLA is small, flat, triangular SESAMOID bone enclosed in the tendon that secures the anterior thigh muscles to the tibia. INTERCONDYLAR NOTCH is found between the condyles on the posterior aspect of femur. It is deep and U-shaped. The MEDIAL and LATERAL EPICONDYLES flank the condyles superiorly.

36. LEG Made up of the TIBIA and FIBULA. They are connected by an INTEROSSEOUS MEMBRANE and articulate with each other both proximally and distally. TIBIOFIBULAR JOINT of the leg allow almost no movement. This makes bones of legs less flexible but stronger and more stable than forearm. Medial tibia joins with proximal femur to form hinge joint of knee and distally with talus bone of ankle. TIBIA Nicknamed the “shinbone”. It receives weight of body from femur and transmits it to the foot. Except for femur, it is the largest, strongest bone in the body. Proximal end has the MEDIAL and LATERAL CONDYLES. An irregular projection called the INTERCONDYLAR EMINENCE separates these condyles. Just inferior to the condyles on the anterior surface is the large, rough TIBIAL TUBEROSITY. This is where the patellar ligament attaches. Tibia is triangular in shape. The ANTERIOR CREST is unprotected by muscles. The MEDIAL MALLEOLUS forms the inner, or medial, bulge of the ankle. The FIBULAR NOTCH is found on the lateral surface of the tibia, opposite the medial malleolus.

37. FIBULA The fibula’s main purpose is to stabilize the ankle joint. The non-weight- bearing bone is stick-like and expands on the ends. Attached at both ends to the tibia. Its upper end is called the HEAD and lower end the LATERAL MALLEOLUS which forms the prominent lateral ankle bulge and articulates with the talus. This bone is heavily ridged and appears to have been twisted a quarter turn.

38. FOOT Bones of ankle (TARSALS), instep (METATARSALS), and toe bones (PHALANGES). Two important functions of foot are to support our bodies weight, serve as lever to propel body forward when we walk and run. TARSALS Ankle – 7 bones Weight bearing tarsals include the TALUS (articulates with tibia and fibula) and CALCANEOUS (heel – Achilles tendon attached here). Other tarsals are CUBOID, NAVICULAR, MEDIAL CUNEIFORM BONES, INTERMEDIATE CUNEIFORM BONES, LATERAL CUNEIFORM BONES. METATARSALS Instep – 5 small long bones. Numbered 1-5 beginning with great toe side of foot. First metatarsal is large, strong, plays role in supporting weight of body. BALL OF FOOT formed by enlarged heads of metatarsals where articulation of metatarsals with phalanges occurs. Proximally, metatarsal 1 articulates with medial cuneiform; metatarsals 2 and 3 articulate with intermediate and lateral cuneiform bones, respectively; and metatarsals 4 and 5 both articulate with the cuboid bone.

39. PHALANGES 14 phalanges of the toes are a good deal smaller than those of fingers and much less nimble. General structure and arrangement are same. Three phalanges in each digit except for great toe, which has only two, proximal and distal. Standing for long periods of time places excessive strain on tendons and ligaments of feet (due to muscles being inactive). This can result in “fallen arches” or FLAT FEET. Running on hard surfaces without proper arch supports can also cause arches to fall because the supporting structures are progressively weakened.