The anconeus muscle extends the elbow, helping to straighten the arm from a bent position. While appearing on the lower arm, it works synergistically with the triceps brachii muscle. It arises from the lateral or outside epicondyle of the humerus and crosses the elbow joint at the rear to insert on the olecranon of the ulna.
Anconeus derives from the Greek and Latin meaning elbow. Ancos in Greek means to bend.
This muscle flexes (bends) the thumb arising near the top of the radius and along the interosseous membrane. Its fibers merge into a flat tendon that passes under the flexor retinaculum. The flexor retinaculum is a tendinous tissue covering the palmar side of the carpals, or wrist bones, forming a tunnel through which all the tendons from the flexor muscles pass in order to control finger movement. A&H-67 is an illustration of the flexor retinaculum. From there the tendon passes down the thumb to insert on the final or distal phalanx, the last little bone.
Pollicis comes from the Latin word pollex, meaning thumb. This muscle is "the long flexor of the thumb." Interosseus is from the Latin and means "between the bones." Retinaculum is the Latin for "hold fast, tether."
Flexor Pollicis Longus M.
Flexor Pollicis Longus M.
You will see that the digits have muscles to extend, to flex, to abduct and adduct it. You could think of the flexors and extenders as the strings and the fingers are the like the puppets being controlled by them. If all the muscles controlling finger and thumb movement were in the hand, the hand would be much too bulky to be useful.
The flexor digitorum profundus muscle flexes the fingers. It arises on the ulna and the interosseous membrane. The muscle merges into a tendon that separates into 4 tendons which course down the arm, passing under the flexor retinaculum. Each tendon finally inserts on the distal phalanx at the end of each finger. The tendon for the index finger is slightly separated from the other three because the index finger is so important. All the tendons are encased in what are called synovial sheathes for protection and to keep them in fine as they pass down the length of the fingers.
Synovial comes from the Greek word syn meaning "together with," and ovial, which comes from ovum, the Latin word for egg. This tissue secretes a viscous fluid, something like the white of an egg, which lubricates the tendons so that they can move back and forth easily.
This muscle bends both the entire hand and each finger at the second joint. It has three heads, the first one arising on the inner epicondyle of the humerus, the second from the coronoid process of the ulna, and the third along a portion of the shaft of the radius. They all converge into one tendon which in turn becomes four tendons that pass under the flexor retinaculum and continue to each of the fingers. These insert on each side of the middle phalanx by separating at their ends allowing the tendons of the flexor digitorum profundus muscle to pass through.
Digitus means finger and digitorum "of the finger" in Latin.
THE FLEXOR CARPI ULNARIS MUSCLE: ANTERIOR AND POSTERIOR VIEWS
The flexor carpi ulnaris muscle flexes the wrist bending it outward. It arises on the posterior side of the humerus, on its medial or inner epicondyle, and courses around the ulna to merge into a tendon which then inserts on two of the carpal bones and the fifth metacarpal bone.
Karpos is Greek for wrist and meta means between.
The palmaris longus muscle assists in bending the wrist. It arises on the medial epicondyle of the humerus and inserts as a tendon into the palmar aponeurosis.
Palmaris Longis M.
Palmaris Longis M.
This muscle assists in bending the wrist forward and to the side. It also arises on the medial epicondyle of the humerus and inserts as a split tendon on the second and third metacarpals.
The abductor pollicis longus muscle assists in bending the thumb, and with it the wrist outward when the palm faces forward. It arises a little above mid shaft along the back of the radius and the interosseous membrane to merge into a tendon that inserts on the base of the first metacarpal, the bone that forms the base of the thumb.
Pollicis Longus M.
The extensor pollicis brevis muscle both extends the thumb and assists in bending the wrist outward. It arises on the back side of the radius and the interosseous membrane, wraps around to the inside of the radius, and courses downward as a tendon to insert at the base of the first phalanx of the thumb.
This muscle extends the thumb and also assists in moving the hand in the direction of the thumb—the forth of back and forth. It arises from the surface of the body of the ulna, just above the abductor pollicis longus, courses downwards and then crosses over the tendons of the extensor carpi radi-alis longus and brevis. It inserts at the base of the last phalanx of the thumb, creating with the extensor pollicis brevis a triangular indented shape known as the "anatomical snuff box." It seems the little indentation at the end of the thumb, just in front of the wrist, caused by the extension of the thumb, was used in earlier times as a place from which to sniff one's snuff.
Pollicis is derived from the Latin word pollex, meaning thumb.
What is the difference between abduction and extension of the thumb? Abduction means movement away from the body. Extension is movement of the body part backward from its normal position. Extension is what you're doing when you are thumbing a ride. When you're thumbing your nose, that's abduction.
The extensor indicis muscle extends the first or pointer finger, even slightly bending it backward. It arises on the rear surface of the shaft of the ulna, about two thirds of the way down, and from the interosseous membrane. It ends its independent course at the first phalanx of the index finger, where it joins the first tendon of the extensor digitorum muscle, from beneath.
Index, indicis, is Latin for "that which points out."
This muscle raises the forearm up, bending the elbow. It arises from the lateral side of the epicondyle of the humerus and inserts on the styloid process of the radius, the flared lower end of the radius.
Brachio is Latin for "of the arm" and radialis refers to the bone called the radius.
This muscle extends the wrist and bends it toward the body when the palm is facing back. It arises from the lateral epi-condyle of the humerus, (same as the brachioradialis but just beneath it). It inserts on the base of the second metacarpal bone located at the base of the index finger.
Carpi is the plural form of carpus, Latin for wrist.
The extensor carpi ulnaris muscle extends and bends the hand outward as when you put your hands up to signal "stop." Like the extensor carpi radialis longus muscle, it arises from the lateral epicondyle of the humerus, sharing a common tendon with that muscle as well as the following one, the extensor digitorum. It passes along the outside of the ulna to insert as a tendon on the base of the fifth metacarpal.
This muscle extends the wrist by bending the hand back as if you were shyly raising you hand in class. Like the extensor carpi radialis longus muscle and the extensor carpi ulnaris muscle, it arises from the lateral epicondyle of the humerus and inserts as a tendon on the base of the third metacarpal.
The extensor digitorum muscle extends all of the joints over which it passes, assists in spreading the fingers, and plays a major role in the coordination of finger movement. It arises from the common tendon shared by the last three muscles discussed, on the lateral epicondyle of the humerus, and passes down over the radius to divide into four tendons which pass over the carpal bones of the wrist. Each of these tendons then inserts at the base of the middle phalanx of each finger.
The extensor digiti minimi muscle enhances the function of the extensor digitorum. It arises from the common tendon discussed above, on the lateral epicondyle of the humerus, passes down the radius, and crosses over the carpals at an angle to join the most lateral of the tendons of the extensor digitorum. It inserts, with the tendon of the extensor digitorum, on the base of the middle phalanx of the little finger.
The tendons of the extensor muscles are enclosed in synovial sheaths. I am not going to show the synovial sheaths in the illustrations because they would prevent your seeing the continuity of the tendons from the arm to the hand to the fingers. Covering the tendons at the wrist like a half bracelet is a fascia called the extensor retinaculum, from the Latin for "that which holds back the extensors." Unlike the flexor retinaculum, which is tendinous and has muscle attachments, this tissue serves only to contain the extensor tendons.
THE BONES OF THE RIGHT HAND AND WRIST: PALMAR VIEW
The bones of the hand and wrist are divided into three areas, the carpals, the metacarpals, and the phalenges. There are eight pebble like bones in the wrist called the carpal bones. These are aligned in two rows of four each. All of them articulate with each other except for the pisiform which sits on top of the triquetral bone. Going from the articulation with the radius to those articulating with the metacarpals, they are: the scaphoid, which articulates with the radius; the lunate; the triquetral; and the pisiform. In the inner or proximal row are the trapezium, found at the base of the thumb, the trapezoid, the capitate, and the hamate bones.There are two little sesmoid bones on the distal end of the metacarpal of the thumb and another, the hamulus, a projection on the hamate bone in the wrist. The metacarpals form the body of the hand and are long and narrow with knobby ends. The phalanges form the fingers and the thumb. The thumb has two phalanges called the proximal and distal bones. The other fingers have three called the proximal, middle and distal bones. Proximal means nearest the center of the body; distal means furthest from the center of the body.
Pisiform Hamate Hamulus
THE BONES OF THE HAND AND WRIST, DORSAL VIEW
Carpal is from the Latin carpus, meaning wrist. Scaphoid means "resembling a boat" and is from the Greek skaphe, skaphos, meaning boat. Lunate means crescent-shaped like a half moon, from the Latin ¡una meaning moon. Triquetral is from the Latin triquetrus, meaning three cornered. Pisiform is from the Latin pisum and -form, meaning "shaped like a pea." Trapezium, from the Greek trapezion, means a shape having four sides, no two of which are parallel. A trapezoid is a four-sided figure with two parallel sides. Capitate is from the Latin caput, meaning head. Hamate is from the Latin hamatus, meaning hooked or "having a hook," hamus, meaning hook in Latin. This bone has a projection that is hook-like. The meta- in metacarpal comes from the Latin and Greek for among or between. This places the metacarpals between the carpals and the phalanges. Phalanges comes from the Latin and Greek phalanx, meaning "a line of battle or a battle array." In Latin phalanger, means "a bone between two joints of the fingers or toes." Palmar comes from the Latin palmaris, meaning the "palm of the hand."
Pisiform Triquetral Hamate
Pisiform Triquetral Hamate
The dorsal interossei muscles assist in the abduction or spreading of the fingers. They arise from the adjacent surfaces of the metacarpal bones and insert at the base of the innermost phalanges of all fingers except the little one. They feather out between each set of metacarpals. The arise on the metacarpals with the fibers meeting in a middle line that then forms tendons. These insert on the proximal ends of the first phalange of the fingers.
These small muscles assist in moving the fingers towards the middle of the hand. They arise on the shafts of second, fourth and fifth metacarpals and pass on the palmar side of these bones to insert at the bases of the first or innermost phalanges of the same fingers and on same side. The one associated with the index finger arises and inserts on the left side of the bones in the right hand, the other two arise and insert on the right side.
The lumbricales muscles move the fingers so that they can hold a pencil. They arise from the palmar part of the tendons of the flexor digitorum muscle, the muscle tendon that divides into four tendons leading to the ends of the fingers, discussed above. They insert in the following manner: on the right hand, palm side up, the lumbrical originating from the tendon leading to index finger arises on the right side of the tendon and inserts into the right mid-side of the innermost phalanx. The next one, arising from the tendon leading to the middle finger, inserts mid shaft on the same side of the innermost phalanx of the middle finger. Between this tendon and the next one, the one leading to the ring finger, muscle fibers arise and join to form a tendon that inserts along right side of the midshaft of the innermost phalanx of the ring finger. The identical pattern is seen between the ring and little finger tendons: the insertion of these joined muscle fibers is along the right side of the shaft of the innermost phalanx of the baby finger.
Lumbricale is Latin for earthworm.
Deep Flexor Digitorum Tendons
Flexor Digitorum Temdon
Flexor Digitorum Temdon
Deep Flexor Digitorum Tendons
The opponens digiti minimi muscle is the partner of the opponens pollicis, causing the little finger to oppose the thumb. Here oppose means to place against, to counterbalance. It arises from the transverse carpal ligament and inserts on the outer border of the fifth metacarpal bone.
Opponens is from the Latin ob- against, ponere- to put or thrust: together meaning thrust against or oppose.
The flexor digiti minimi brevis muscle assists the little finger in bending. It arises from the hook of the hamate bone and nearby flexor retinaculum to insert, along with the abductor digiti minimi muscle, at the outer base of the fifth phalanx.
This muscle moves the little finger away from the fourth finger, as when you spread out your fingers. It can also act as a flexor muscle, although sometimes a separate flexor muscle is found. The abductor digiti minimi muscle arises from the carpal bone called the pisiform and then traverses the fifth metacarpal to insert at the base of the first phalanx of the little finger.
Pisum in Latin means pea and form means shape.
This muscle allows you to grasp something. It arises in two heads. The transverse head arises from along the side of the third metacarpal bone, its fibers merging with its neighbors to insert at the base of the innermost phalanx of the thumb. The oblique head arises along the bottom half of the second metacarpal and then from the surfaces of the carpal bones that are just next to the second metacarpal. Its fibers merge to insert on the base of the inner portion of the first phalanx of the thumb.
It has been said that one of the reasons we developed to such a degree as a species can be traced to our opposable thumb and the advantage it gives us in being able to use our hands as a versatile tool. You should be able to understand better our remarkable dexterity after I have described all of the many muscles involved in the movements of the thumb which include muscles of the arm as well as in the hand.
The opponens pollicis muscle moves the thumb so it can oppose the other fingers. It arises from the transverse carpal ligament which is also known as the flexor retinaculum, discussed above. Other muscles that arise from it: the flexor pollicis brevis and the opponens pollicis on the thumb side of the palm, and the flexor digiti minimi and the opponons digiti minimi on the outside of the hand, towards the little finger. The opponens pollicis muscle inserts along the outer border of the first metacarpal, the bone located in the palm at the base of the thumb.
This muscle keeps the underlying muscles in place and pulls the skin toward the center of the palm when you make a fist. It arises from the flexor retinaculum, covers the opponens and abductor digiti minimi muscles, and inserts in the skin at the outer border of the palm.
Opponens Pollicis M.
Palmaris Brevis M.
Opponens Pollicis M.
Palmaris Brevis M.
The flexor pollicis brevis muscle allows the thumb to move over the palm of the hand. It arises in two sections; the first begins under and slightly to the inside of the superficial part which arises from the flexor retinaculum; the second originates as small deep muscle fibers from the carpal bones just at the base of the fifth metacarpal bone. Both sections unite to insert at the base of the first phalanx.
Flexor Pollicis Brevis M.
Flexor Pollicis Brevis M.
The abductor pollicis brevis muscle, the last of the seven thumb muscles, moves the thumb perpendicular to the palm of the hand. Arising on the flexor retinaculum it lies just over and adjacent to the flexor pollicis brevis muscle and inserts on the base of the first phalanx of the thumb.
The major bones of the back are the 24 vertebrae which make up the vertebral column. They are stacked one on top of the other, and become increasingly large as they descend, carrying more and more of the body weight. Seen from the side they make a gentle double S shape from top to bottom that ends with the sacrum, where a tail would hang if we still had one. The curves correspond to the different sections of the spinal column. The first curve corresponds to the neck and it is made up of seven cervical vertebrae. The top two vertebrae have their own names. The first which holds up the skull, is called the atlas (after the Greek god of that name who holds the heavens on his shoulders). The second, which assists in turning the head, is called the axis. The next twelve, completing the first S curve, are called the thoracic vertebrae and are the ones to which the ribs are attached. The last five, forming an opposing curve to the thoracic vertebrae, are the lumbar vertebrae. The sacrum completes the second S curve. It is formed as a fusion of the final five vertebrae.
The other bones involved with the musculature of the back are: the occipital bone of the skull; the scapulae; the ribs; and the pelvis.
" Cervical -Vertebrae
\ Thoracic ' / Vertebrae
Vertebra is from the Latin vertere, to turn. Axis comes from the Greek axon, meaning axle. Cervical is from the Latin word cervix, meaning neck. Thorax is Greek for breast. Lumbar is from the Latin word lumbus, meaning loin—lumbar meaning "of the loins." Sacrum comes from the Latin word for "the sacred bone."
THREE VIEWS OF THE TENTH AND ELEVENTH THORACIC VERTEBRAE
Because they have numerous jobs to perform these bones are enormously complex. They provide the structure for holding us erect. They also protect the spinal cord and allow for its branches to pass out through openings created by the neat fitting of one vertebra below the other in such a manner that the spinal cord and its fluid are contained and protected. The nerve branches emerge from between each pair of vertebrae to travel to all parts of the body. The body of each vertebra is drum shaped and cushioned by a disc of a softer, cartilaginous material that allows each vertebra to move over the other. On the sides of the body are facets—little dish-like formations—where the ribs attach. In the upper thoracic vertebrae these facets are shared—a demi facet in the one above and a demi facet in the one beneath. In the lower vertebrae, these facets are complete on each vertebra. On the back side of the vertebrae are various projections. The inferior articular surface of the upper vertebra articulates with the superior articular surface of the one below. There are two transverse processes, one on each side, like wings, which serve as muscle attachments and also provide a second articular surface for the rib as it begins arching out and around the body's
Inferior Articular Process
Superior Articular Facet
Mamillary Process T-10
Interior Vertebral Notch
Superior Articular Facet
Interior Vertebral Notch
Inferior Articular Process
Body Disk upper organs. On each vertebra, in the middle, between these processes, is a spinous process. In the cervical vertebrae these processes point obliquely downward. In the upper thoracic vertebrae they point outward but as the vertebrae descend, they point increasingly downward again. In the lumbar region they again point outward. When you look at the spine from the rear, with all vertebrae lined up, the transverse processes seem to form a gutter on each side of the spinous process. They are filled with very small muscles that zigzag back and forth, connecting one vertebra with the next or even with one several vertebrae away. These muscles not only serve to function in the way we move our torso; they also cushion and smooth over the projections of the vertebrae.
This muscle and the one next to it, the splenius cervicis, also assist in holding the head erect and in turning the head and neck to the side. It arises from the spinous processes of the top three or four thoracic vertebrae and the spinous process of the seventh, or bottom, cervical vertebra. It also arises from a ligament which attaches to the nuchal area at the mid-base of the occipital bone and descends to the end of the cervical spine. It then courses upwards and slightly laterally to insert in two places—as a tendon along the rough bone just below the superior nuchal line, and on the mastoid process.
Splenius is from the Greek word splenion, meaning bandage.
This muscle arises from the spinous processes of the third, fourth, fifth and sixth thoracic vertebrae. As it rises it becomes three or four separate fiber bundles that insert tendinous fibers on the transverse processes of the upper three or four cervical vertebrae.
THE TRANSVERSOSPINALES MUSCLES
The transversospinal group of muscles arise and insert on the vertebrae. They keep us erect, and allow our backs to twist and turn.
Transverse is from the Latin verb transversieri, "to turn across, cross over."
THE ROTATORES BREVIS AND THE ROTATORES LONGUS MUSCLES
Of the transversospinales group the deepest are the rotatores brevis and the rotatores longus muscles, very small muscles that assist in turning the spine, filling in the groove formed by the spinous processes and the transverse processes of the vertebrae. They form a zigzag pattern all the way from the sacrum to the axis. The brevis muscle arises from the transverse process of one vertebra and inserts at the base of the spinous process of the vertebra above it. The longus muscle arises also on the transverse process of one vertebra but skips a vertebra to insert on the spinous process of the second above it, giving it an oblique direction.
Interspinales Lumborum M
The intertransversarii muscles bend the spine to the side, at the levels of the neck and the waist. At the level of the neck they are located between the transverse processes of the cervical vertebrae where they consist of a posterior and anterior set. At the level of the waist they appear between the transverse processes of the last three thoracic vertebrae and the first lumbar vertebra where they consist of a lateral and medial set.
The interspinales muscles give support in keeping the spine extended—straightened out. They lie between the spinous processes of all the cervical vertebrae except the atlas, down to and including the top two thoracic vertebrae. They then show up again on the bottom thoracic vertebra and between the five lumbar vertebrae.
The base of rotatores, rota, means wheel in Latin.
Forming the next layer of deep muscles is the multifidus muscle which extends and rotates the back. Because it comes in separate bundles, this muscles looks like many small muscles. It covers the deep layer of muscles I have just discussed and helps to fill up the grooves on each side of the bony vertebrae. It arises from the top of the sacrum, from the inner surface of the iliac spine of the pelvis, from the mammilllary processes of the lumbar vertebrae, from the transverse processes of the thoracic vertebrae, and from the articular processes of the bottom four cervical vertebrae. Its fibers course upward crossing five vertebrae to insert on the spinous process of the fifth vertebra from where it started. This pattern of attachment applies from the fourth lumbar vertebra to the axis. Deeper fibers of this muscle cross fewer vertebrae.
Multifidus is from the Latin multus meaning many and jindere meaning to cleave; thus it means "many cleavings" or "divided into many parts."
THE SEMISPINALES MUSCLES; CAPITIS, CERVICIS AND THORACIS
Running next to and over the multifidus muscle are the cervical and thoracic semispinales muscles. The capitis section is just above. The semispinales muscles assist in extending and rotating the spinal column. The capitis muscle assists in holding the head erect and in turning it. It arises from the transverse processes of the top six thoracic vertebrae and inserts in between the superior and inferior nuchal lines of the skull's occipital bone. It is divided into two sections by intersecting tendinous fibers near the axis. The thoracic fibers arise as tendons from the transverse processes of the eleventh or tenth to the sixth thoracic vertebrae and insert on the spinous processes of the top four thoracic vertebrae. The cervical fibers arise similarly from the transverse processes of the top five or six thoracic vertebrae and insert on the spinous processes of the fifth to the axis or second cervical vertebrae.
Semi is Latin, from the Greek hemi, meaning half or partly. Spinales is from the Latin spinalis meaning "of the spinal cord." Unlike the Multifidus that covers the whole length of it, these muscles cover roughly half or part of the spinal column.
The spinales muscles have three parts—the capitis, the cervi-cis and the thoracis. The spinalis cervicis arises from the spinous processes of the top two thoracic vertebrae and the seventh cervical vertebrae to insert on the spinous process of the axis. The spinalis thoracis arises from the inner portion of the tendinous mass of the erector spinae and from the sacrum as well as from the spinous processes of the top two lumbar and bottom two thoracic vertebrae. It inserts into most or all of the spinous processes of the upper thoracic vertebrae. In dissection this muscle is hard to separate from the semispinales muscle which lies beneath it, especially the capitis portion, which blends with the semispinales capitis muscle.
Dorsi is Latin for "of the back."
The longissimus dorsi muscle has three distinct parts, the capitis, the cervicis and the thoracis.The capitis muscle assists in holding the head erect as well as in rotating it toward the same side as the muscle which is contracting. It arises from the transverse processes of the top four thoracic vertebrae and courses upwards to insert on the mastoid process of the skull. The cervicis muscle assists in bending the top of the neck and helps in keeping the cervical spine erect. It arises as narrow tendons from the transverse processes of the top four thoracic vertebrae and rises upwards just lateral to the longissimus capitas muscle to insert on all of the transverse processes of the axis as far as the sixth cervical vertebra. The thoracis portion assists in backward and sideward bending. It also assists in keeping the spine erect as well as pulling the ribs downward, thus helping with breathing. The thoracic muscle arises from the tendinous mass covering the sacrum and lies lateral to the spinales dorsi. It courses upward inserting in two areas—medially it attaches to the transverse processes of the vertebrae, and laterally it attaches to the lower nine or ten ribs, just where they begin to curve away from the spine.
LONGISSIMUS DORSI MUSCLES
LONGISSIMUS DORSI MUSCLES
Longissimus dorsi means "longest of the back.". The longis-
simus goes from the sacrum to the base of the skull.
-Issimus on the end of a Latin word is equivalent to our -est ending of an adjective, meaning the most.
The most lateral of this layer of muscles is called the ilio-costalis muscle which assists in extending the back and bending sideward. It arises from the tendinous mass covering the sacrum just lateral to the spinalis dorsi and the longis-simus dorsi, but is not contingent with those two, being somewhat separated from them. It has three parts. The first, the lumborum, arises from the the fascia that covers the sacrum, and inserts onto the lower or inferior borders of the lower six or seven ribs. The second part, the thoracis, has fibers that arise from the upper borders of the lower six ribs just medial to where the lumbar fibers insert, and it inserts on the upper borders of the top six ribs and onto the transverse process of the lowest cervical vertebrae. The third part, the cervicis, has fibers which arise from the third through sixth ribs and insert onto the transverse processes of the fourth through sixth cervical vertebrae.
This illustration is a frontal view the rib cage with the bones of the shoulder girdle: the clavicle, the scapula, and the humerus. There are twelve ribs, ten of which are attached posteriorly to the spinal column and anteriorly to the sternum (one of the unpaired bones). The ribs do not directly attach to the sternum. Instead there are cartilaginous struts called the costal cartilages that attach to the sternum and to the ribs. Some struts are separate from each other while the lower ones are fused in varying patterns only one of which is shown here. Ribs 11 and 12 are the "floating," attached to the spinal column but not to the sternum. Their muscle attachments keep them in place. The top of the sternum is called the manubrium and looks like a separate bone hinged or joined to the body of the sternum. At the bottom is the xiphoid process. The ribs embrace and contain some of our vital organs—the heart, the lungs and the esophagus—and form a protective structure for them. Assisted by the action of the diaphragm many of these muscles are involved with breathing.
Thorax is Greek meaning chest or brestplate. Sternum is Latin and comes from the Greek word sternon, meaning breastbone. Manubrium is Latin for handle or haft.
Clavicle Scapula Manubrium
Clavicle Scapula Manubrium
THE STERNUM, THE COSTAL CARTILAGES AND PART OF TEN RIBS, VENTRAL VIEW
THE RIBCAGE WITH THE SPINAL COLUMN, SHOWING THE SEVENTH CERVICAL VERTEBRA, THE TWELVE THORACIC VERTEBRAE, AND THE FIRST LUMBAR VERTEBRA, A POSTERIOR VIEW
This view allows you to see the two floating ribs.
7th cervical Vertebra
2 Floating Ribs
2 Floating Ribs
7th cervical Vertebra
THE RIB CAGE OR THORAX WITH THE TWELVE THORACIC VERTEBRAE, LEFT LATERAL VIEW
You can see the curve of the spinal column as well as the varying directions of the vertebrae's spinous processes.
This muscle is a series of small muscles that assist in drawing the ribs downward, decreasing the size of the lungs and helping to express air or breath out. They arise on the inner surface of the sternum and on the xiphoid process to insert on the costal cartilages. There are about five of them and they insert in an almost horizontal direction on the sixth costal cartilage, with the angle of their directions becoming more vertical as they attach to each of the higher costal cartilages.
There are two layers of intercostal muscles and the view here shows the innermost layer, the intercostales interni muscles. These muscles draw the ribs together compressing the chest and lungs to expel air in the breathing out part of respiration. There are eleven on each side positioned between each of the twelve ribs. While their direction is almost vertical at the sternal end, they run more and more obliquely as they travel around the bend of the ribs. Running perpendicular to the intercostales externi muscles they arise from the lower inner surface of each rib as well as from the costal cartilage to insert on the upper surface of the rib below.
The eleven paired intercostales externi muscles lie right on top of and perpendicular to the intercostales interni muscles and are a bit thicker. Along with the action of the scalenus muscle which attaches to the first rib, they act to lift the rib cage, expanding it in the breathing-in part of respiration. They arise on the lower border of each rib and insert on the upper border of the rib below.
Even though this is called the serratus anterior muscle, it appears on the side of the chest wall. It rotates the scapula, allowing for a full range of arm movement. It arises from the outer surface and upper border of the first nine ribs and it courses around the rib cage in the form of about nine different bundles to join in a sheath of muscle which inserts all along the inner border of the scapula, from its upper to lower tip. The next two muscles described below are also serratus muscles, this time appearing posteriorly. Both get their names from their saw-tooth-like appearance which is enhanced in the anterior muscles as they interdigitate with the abdominal muscles.
Serratus is Latin for "notched, toothed or saw-like."
THE SERRATUS POSTERIOR MUSCLES, SUPERIOR AND INFERIOR
There are two pairs of serratus posterior muscles, one superior and the other inferior. The superior serratus posterior muscles lift the ribs, increasing the chest cavity to enhance inspiration (breathing in). The superior serratus posterior muscle arises from the spinous processes of the last or seventh cervical vertebra and the first three thoracic vertebrae as four separate muscles which lie next to each other. Each one arises as an aponeurosis or tendinous sheath-like tissue from the ligmentum nuchae, the ligament that comes down from the base of the skull to cover the spinous processes of the cervical vertebrae. The muscle groups course obliquely outward and downward as flat muscles to insert along the upper borders of the second to the fifth ribs. The lower muscle is quite separate from the upper one by about three ribs' distance. It pulls the ribs outward and downward. It arises from the spinous processes of the last two thoracic vertebrae and the first two lumbar vertebrae as four seperate muscles lying next to each other. Like the superior muscle, they arise as an aponeurosis and about half way in their upward and outward path they become flat muscles that insert on the lower borders of the ninth to the twelfth ribs.
SERRATUS POSTERIOR MUSCLES
The levatores costorum muscles are deeper than the posterior serratus muscles. They lie just beneath the longissimus dorsi muscle discussed in the section on the back. As Latin translation tells us, they are rib lifters, thus assisting in breathing in. They also help to keep the back erect and to aid in its rotation as well. There are twelve of them. They arise as attachments to the spinous processes of the last cervical vertebra and eleven of the thoracic vertebrae. In the case of the bottom four, there are two parts to each little muscle bundle, a brevis and a longus, not unlike the rota-tores seen above in the section on the back. The brevis, or short, fibers insert on the rib adjacent to the spinous process from which they arose. The longus fibers travel obliquely downward to insert two ribs below the spinous process from which they arose.
LEVATORES COSTORUM MUSCLES
The pectoralis minor muscle is a rib lifter, helping to breathe in. It also assists in rotating the scapula by pulling the arm in towards the body. It arises as three bundles of fibers from the upper borders of the third to fifth ribs, just next to the junctures with the costal cartilages. As the three bundles of muscles course upwards they converge into a tendon which attaches on the coracoid process of the scapula.
The subclavius muscle, which brings the shoulder forward and down, arises where the first rib joins with its costal cartilage and courses outward to insert on the underside of the clavicle.
Subdavious is Latin for "under the clavicle."
Pectoralis Minor M
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