Skeleton / Shoulder / elbow

Question 1

Skull can be divided into 2 parts
1- Bones of the cranial
2- Bones of the face

*All the bones of the jaw can be classified as suture

Answer 1

Parietal bone – There are two parietal bones that together form the top and upper sides of the skull. They flank the midline of the top of the skull directly posterior to the frontal bone and extend rearward to the crown of the head. Each parietal articulates with the frontal bone, the opposite parietal, the occipital, and the temporal and sphenoid bones of each side of the skull.

Question 2

Occipital bone – The occipital is a roughly saucer-shaped bone at the back and lower part of the skull. Approximately two-thirds down the length of the bone and medially you will find the foramen magnum. The cranial cavity (inside of the skull) communicates with the vertebral canal (through which the spinal cord runs) via this foramen. There is an occipital protuberance present medially to which a number of muscles attach. At the level of the occipital protuberance there is a mildly raised lateral running ridge of bone called the superior nuchal line. A couple inches inferior to this line there is another similar line called the inferior nuchal line. As with the occipital protuberance, both of these features serve as sites of attachments for muscles. The occipital bone articulates with the parietal and temporal bones to the anterior, and with the inferior first cervical vertebra (the atlas).

Answer 2

Temporal bone – The temporal bone is located at the base and side of the skull just anterior to the occipital, inferior to the parietal, and posterior to the sphenoid bone. The posterior temporal bone contains the acoustic meatus (the ear hole) and just anterior to the meatus the temporal articulates with the mandible (the jawbone). This particular joint is called the ‘temporomandibular joint’.

There are two other bony features of interest, both found adjacent to each other at the inferior and posterior part of the temporal bone behind the acoustic meatus.

The styloid process, a small spike of bone protruding downward
The mastoid process, a much larger bump of bone both serve as important attachments sites for muscles. The styloid process, an attachment site for the tongue is not palpable. However the mastoid process generally is palpable by running your finger down the bone just posterior to the ear. The most inferior bump you feel is the mastoid process.

Question 3

Sphenoid bone – While the sphenoid looks to be a bilateral pair of bones like the parietal and temporal bones, it is actually a single bone that spans the skull from side to side. It is one of the seven bones that articulate to create the eye orbit. The superficial aspect of the sphenoid lies just posterior to the bony ridge we call the orbit or eye socket

Answer 3

Nasal bone – The nasal bones are two small bones that vary in size and shape in different individuals (why our noses look different). They create the bridge of the nose (your sunglasses sit on them) and flank the midline of the nose just anterior and inferior to the frontal bone.

Question 4

Maxilla – The maxilla is the bone into which your upper row of teeth is set and it forms the roof of the mouth. It also creates the most medial aspects of your ‘cheek bones’.

Answer 4

Zygomatic bone – This bone forms the lateral and posterior component of your ‘cheekbones’, the most curved portion. It articulates with the frontal, sphenoid, maxilla, and temporal bones.

Question 5

Mandible – This is your jaw. The lower row of teeth is set into the mandible. It articulates bilaterally with the temporal bone to form the temporamandibular joints (Figure 13.10). You can locate the joint by placing your fingers just anterior to the acoustic meatus then repeatedly opening and closing the mouth. This is the most freely moving and least stable bone in the skull. Not surprisingly, it is one of the most frequently fractured bones in the skull

Answer 5

THE SPINE

Question 6

Spinal Column / Vertebral Column - 33 bones interlock, spanning over 5 sections;
1- Cervical Spine (7)
2- Thoracic Spine (12)
3- Lumbar Spine (5)
4- Sacral Spine (5 fused) 
5- Coccyx (4 or less fused)

24 of which are MOVABLE.

Answer 6

3 basic parts of the discs:
1- anterior part (the BODY)
2- The spinous and transverse processes- posterior projections, serving as articular surfaces for adjacent vertebrae and as sites of attachment for ligaments and muscles.
3- Vertebral Foramen - center hole spine runs through

(1) an anterior rounded chunk of bone called the body. This part of the bone is what carries the weight of the body above it. The bodies of the vertebrae become thinner as they go up the vertebral column (less weight to support allows smaller size). Vertebral bodies are separated from each other by intervertebral discs, made of tough fibrocartilage.
(2) A group of posterior projections, the spinous and transverse processes, serving as articular surfaces for adjacent vertebrae and as sites of attachment for ligaments and muscles.
(3) A large central hole called the vertebral foramen. The sequential stacking of the vertebrae on top of each other provides a canal through which the medulla spinalis (spinal cord) passes from its lower terminations up to its passage into the cranium and the brain.

Question 7

The chest, or thorax, formed by
(1) the articulations of the first seven thoracic vertebrae with the ribs to the posterior and the sternum to the anterior,
(2) the articulation of the eighth, ninth, and tenth pairs of ribs with the corresponding vertebrae as with the first seven but they share a single articulation with the sternum to the anterior, and
(3) the articulation of the eleventh and twelfth pairs of ribs with the corresponding vertebrae. These last five pairs of ribs are sometimes called ‘false ribs’ or ‘floating ribs’ as they lack attachments to the sternum.
The first rib articulates with the manubrium just inferior to the clavicle (collar bone). Ribs 2-5 can be palpated easiest at their articulations with the sternum. For ribs 6-10, the process is to identify rib five then follow it with your fingers laterally to a point under the arm then palpate each inferior rib. For ribs 11-12 you will need to follow rib ten around just lateral to the vertebral column and push with a degree of force to feel the floating ribs.

Answer 7

RIB CAGE
The function of these bones is primarily to form the support and protective framework for all of the organs and tissues within the chest cavity and the abdominal cavity inferior to it. Although the rib cage is quite robust and impact resistant, it is also somewhat mobile. The cartilaginous joints to the anterior allow for a degree of movement that is helpful not only in external respiration (breathing) but also adds to the protective and shock absorptive nature of the ribs. The chest is quite durable and even though it has been reported that severe sneezing attacks have resulted in a fractured rib, just think of all of the boxing, mixed martial arts, rugby, and football impacts at the chest that have taken place without injury, even with direct, high force, and intentional blows.

Question 8

SPINAL MUSCLES

Answer 8

Sternocleidomastoid – Attaches to both the sternum and clavicle near the sternoclavicular joint (near the manubrium) and runs upwards and attaches to the mastoid processes just posterior to the acoustic meatus (behind the ear) and produces movements such as nodding and turning of the head. When recruited unilaterally, the sternocleidomastoid tilts the head to its own side and can rotate the head so it faces the opposite side. When recruited bilaterally, it flexes the neck or raises the sternum. This latter action is contributory to forced inspiration (voluntarily taking as big of a breath as you can). The sternocleidomastoid is quite pronounced in comic book super heroes. It will also be relatively pronounced in powerlifters who do heavy bench presses routinely, as the muscle is recruited to elevate the chest in order to shorten the distance between the chest and the arm lock-out position at the top of the movement.

Question 9

Scalenus – There are three scalenus muscle segments, the anterior, medius, and posterior. They are attached to the transverse processes of the second through seventh cervical vertebrae and the first two ribs.
The scalenus anterior and medius- when contracted elevate the first rib or rotate the neck to the opposite side of the body (from the muscle).
Posterior scalenus - acts to elevate the second rib and tilts the neck to the same side of the body (same side as the active muscle).
The scalenus lies along the anteriolateral aspect of the neck and assists in lateral flexion of the head against the resistance (tilt the head to the left or right). This is a deep muscle and is likely not palpable except in exceptional instances

Answer 9

Erector Spinae – This is not a single muscle rather the term is used to name a group of muscles that maintain normal vertebral extension (they maintain posture) and provides for extension of the vertebral column against resistance. 3 basic muscle groups:

Iliocostalis – three defined segments; cervical, thoracic, and lumbar
Longissimus – three defined segments; cranial, cervical, and thoracic
Spinalis – three defined segments; cranial, cervical, and thoracic

Question 10

iliocastalis / longissimus / Spinalis:

The iliocostalis is the most lateral of the group, the longissimus is more medial, and the spinalis is the most medial. The erector spinae run the length of the vertebral column on both sides attaching to vertebral processes and posterior rib segments along the way. In a well-developed power athlete they may appear quite large, similar to having two baguettes along each side of the vertebrae. If you watch a lean individual walk from behind you can see the erectors contracting alternately with each opposing step. This aids in ambulation and in maintenance of posture. These muscles can be recruited to extend the vertebral column in part or in total. They have a heavy postural role in maintaining normal kyphotic and lordotic curves in both unloaded and loaded conditions.

Answer 10

Psoas major – The psoas major is not precisely an axial skeleton muscle. It is a fusiform and deep muscle that attaches proximally to the costal processes of the lumbar vertebrae, the lateral surfaces of the twelfth thoracic vertebra, and lumbar vertebrae one through four. Its distal attachment is on the lesser trochanter of the femur thus making it more properly a hip muscle. It is generally considered a hip flexor and a contributor to the forward leg swing of walking. However, if the hip is held immobile the psoas contributes to flattening or rounding of the lordotic curve, or if the erector spinae are strongly invoked the psoas can contribute to exaggerating the lordotic curve. If you can control and manipulate the arch and round in your low back, you have pretty decent control of your psoas (among many others).

Question 11

Quadratus lumborum – The quadratus lumborum is a moderately deep four sided muscle located in the area of the lumbar vertebrae. Its contraction can produce a number of actions; lateral flexion of vertebral column if only one of the pair is recruited, extension of lumbar vertebral column with bilateral contraction, and during forced exhalation it immobilizes the twelfth rib pair. Its proximal attachment is on the iliac crest (top of the hip-bone) and it is attached distally to the lower border of the twelfth rib and the transverse processes of the upper four lumbar vertebrae.

Answer 11

Rectus abdominis – The rectus abdominis muscle is a bilateral paired muscle that courses vertically on each side of the anterior wall of the abdomen. The two lateral muscles are separated by a medial band of connective tissue called the linea alba.
The rectus abdominis extends from the pubic symphysis and pubic crest inferiorly to the xyphoid process and fifth through seventh costal cartilages superiorly. There are three transverse fibrous bands called tendinous inscriptions. Combined with the linea alba, these connective tissues divide the active musculature of the abdominis rectus into six roughly symmetrical segments. In very lean or very muscular individuals, the defined appearance of these segments is termed a ‘six pack’ or of more antiquarian origin, ‘washboard abs’.

The rectus abdominis is an important anterior postural muscle responsible for maintaining a balanced isometric force (countering the erector spinae) for normal posture or actively flexing the lumbar spine. The rectus abdominis can also assist in forced respiration, as its active contraction can reduce abdominal and thoracic volumes

Question 12

External Obliquus – The external obliquus (commonly called the external oblique), on the lateral and anterior abdomen, is a broad, thin, and roughly quadrilateral muscle. In general the external obliquus is not visible due to subcutaneous fat deposits and the relatively small mass of the muscle. The muscle arises from eight superior points of attachment on the external and inferior borders of the fifth through twelfth ribs. The fibers of the muscle are arranged in an oblique fashion (on an angle). The muscle attaches inferiorly on the anterior half of the outer lip of the iliac crest. There is a coalescence of connective tissue (aponeurosis) at the lower border of the external obliquus muscle that forms the inguinal ligament. The muscle acts to pull the rib cage downward (flexion of the vertebral column) either bilaterally or unilaterally. This movement compresses the abdominal cavity thus increasing intra-abdominal pressure. This particular function contributes to vertebral stability during the execution of the Valsalva maneuver (attempted exhalation against a closed glottis) and it also contributes a small amount to both flexion and rotation of the vertebral column. To palpate this muscle, place your palm just below the most lateral and inferior aspect of the rib cage and alternately laterally flex the trunk (with considerable isometric force at the bottom) then extend it in the opposite direction.

Answer 12

Internal obliquus – The internal obliquus muscle (commonly called the internal oblique) lies just underneath the external oblique so it is not palpable. It is quite similar in structure to the external oblique but its fibers are oriented on the diagonal but perpendicular to the external oblique muscle. Its proximal attachment is through the thoracolumbar fascia of the lower back and the anterior of the iliac crest (the top of the hip bone). The muscle attaches distally to the inferior borders of the tenth, eleventh, and twelfth ribs and across to the linea alba. The internal oblique performs two basic functions. It is an antagonist (opposing muscle) to the diaphragm, compressing the thoracic cavity to drive exhalation. It also acts to rotate and bend the trunk by pulling the rib cage and midline towards the hip and lower back, of the same side as the active muscle is located – a same side rotator

Question 13

Diaphragm – The diaphragm is a dome-shaped muscle with a substantial connective tissue component that forms a septum separating the thoracic and abdominal cavities. Its shape follows the contour of the area defined by the ring of the rib cage and the vertebral column with the most peripheral portion consisting of muscle fibers that attach to the circumference of the ribs and converge centrally to attach to a central, sheet-like tendon. One segment of the muscle arises from the back of the xyphoid process, another segment that arises from the inner surfaces of the lower six ribs, and another segment arises from the anterior lumbar vertebrae.

The diaphragm is the primary muscle of breathing (external respiration). During inhalation, when the diaphragm contracts, the central tendon is pulled downward thus increasing the volume of the thoracic cavity. This reduces intra-thoracic pressure to lower than atmospheric pressure (forms a vacuum) thus forcing air to be drawn into the lungs. When the diaphragm relaxes, the elongation of the muscle allows the central tendon to move back up, reversing the process and expelling air.

Answer 13

lol

Question 14

3 joints are the 
1-  Acromioclavicular
2- glenohumeral
3- sternoclavicular joints. 
Together, structurally and functionally, they form the freely moving joint system we call the shoulder. There is a minor drawback to such mobility, it is accompanied by relative instability and the shoulder can be injured more easily than other joints. Minor in that it is still a robust and tough joint that when appropriately strengthened and correct movement techniques used, the chance for injury is reduced. For any coach or fitness trainer, it must be understood that strengthening the shoulder musculature, the prime movers specifically, is the most important aspect of injury prevention and of performance enhancement relative to shoulder movement.

Answer 14

The bone of the shoulder closest to the axial skeleton is the clavicle. The common term for the clavicle is the ‘collar bone’.
The clavicle articulates with the sternum anteriorly and to the scapula posteriorly. When viewed from the front, the clavicle has a somewhat flat appearance and forms a very shallow and long ‘S’ shape when viewed from above.
The second and most posterior bone of the shoulder is the scapula.
SCAPULA- is almost triangular in shape and is a flat bone that lies over the ribs of the upper back, lateral to the vertebral column (one scapula on each side of the vertebral column). The last bone of the shoulder set is the long bone of the upper arm, the humerus. The articulation of the humerus with the scapula is the crux of arm movement and as such, the scapula must be considered as critically important in any analysis of arm movement in sport or exercise.

Question 15

3 joints are the 
1-  Acromioclavicular
2- glenohumeral
3- sternoclavicular joints. 
Together, structurally and functionally, they form the freely moving joint system we call the shoulder. There is a minor drawback to such mobility, it is accompanied by relative instability and the shoulder can be injured more easily than other joints. Minor in that it is still a robust and tough joint that when appropriately strengthened and correct movement techniques used, the chance for injury is reduced. For any coach or fitness trainer, it must be understood that strengthening the shoulder musculature, the prime movers specifically, is the most important aspect of injury prevention and of performance enhancement relative to shoulder movement.

Answer 15

The bone of the shoulder closest to the axial skeleton is the clavicle. The common term for the clavicle is the ‘collar bone’.
CLAVICLE - articulates with the sternum anteriorly and to the scapula posteriorly. When viewed from the front, the clavicle has a somewhat flat appearance and forms a very shallow and long ‘S’ shape when viewed from above.
The second and most posterior bone of the shoulder is the scapula.
SCAPULA- is almost triangular in shape and is a flat bone that lies over the ribs of the upper back, lateral to the vertebral column (one scapula on each side of the vertebral column).

HUMERUS - The last bone of the shoulder set is the long bone of the upper arm, the humerus. The articulation of the humerus with the scapula is the crux of arm movement and as such, the scapula must be considered as critically important in any analysis of arm movement in sport or exercise.

Question 16

Clavicle – The clavicle acts like a strut (structural support resisting a load along its length) to support the upper extremities. It also serves to protect the underlying subclavian neurovascular bundle. The complete length of the clavicle is easily palpated on anyone. It is quite superficial. The muscles attaching to it do not obscure its superior and anterior surface in front of the neck. If you look at the little dip in the line of bones across the front of the shoulders, just below the neck, the bump lateral to the suprasternal notch (the medial dip you see) is the medial end of the clavicle (Figure 14.3). You can walk your fingers laterally along the length of superior surface of the clavicle until you get to the point of the shoulder where it articulates with another posterior bone of the shoulder joint, the scapula. The clavicle is a critical bone in shoulder and arm function, a fracture is quite painful and frequently renders the arm on the fractured side non-functional. About five percent of all fractures diagnosed and treated in the US are clavicular fractures. The most common mechanism of injury involves a direct and large magnitude force applied to the lateral aspect of the shoulder as a result of a fall or contact in sport (or car accident). An illustration of the importance of the clavicle in arm movement can be found in the historical and relatively gruesome military tactic for preventing prisoner resistance in forward hostile environments, to fracture both clavicles of the prisoner, thereby preventing any aggressive prisoner actions with the upper body but maintaining their lower body mobility.

Answer 16

Scapula – Parts of the scapula are readily palpable depending on the degree of musculature of the individual palpated (Figure 14.4). It is much easier to palpate the scapula on very slightly built endurance runners and dancers than it is on heavily muscled strength and power athletes. The most prominent feature of the scapula is the spine of the scapula, or the scapular spine. It is a posterior projection off of the superficial face of the scapula, about 2/3’s of the way up its length. Most people will refer to this feature as the ‘shoulder blade’. The spine will feel like a bony ridge that runs obliquely, rising at a shallow angle as it crosses the upper back, medial to lateral (Figure 14.5). As will be the case in most large boney features, several muscles will attach to the spine. The large trapezius muscle attaches on the superior surface of the spine and prevents palpation of the upper medial border and the superior border of the scapula. Palpation of the spine out to the most lateral (furthest out) portion of the scapular spine will take you to the point of the shoulder. This structure is the acromion process, the flattened terminal portion of the scapular spine (Figure 14.6). This area should be familiar as the acromion process articulates with the clavicle to form the acromioclavicular joint.

NOT connected by any ligaments to axial skeleton - only my muscles.

Question 17

Coracoid Process:
There is another important process present on the scapula, the coracoid process. It is a moderately sized projection on the anterior and inferior side of the scapula and can be palpated on the anterior side of the body. Stand in front of someone, place the palm of your hand (approximately) on the top of the shoulder. Wrap your thumb down to the front of the shoulder to a point in the middle of the fossa or ‘hollow’ that appears below the clavicle and between the arm and chest. By applying firm pressure with your thumb and having your subject move his shoulder slightly forward and backward, you should feel a bump that moves when the scapula moves. This palpation may possibly cause a small degree of discomfort.

Answer 17

Glenoid Fossa:
Just inferior to the scapular spine along the lateral border there is a shallow, somewhat bowl shaped oval depression called the glenoid fossa (refer to Figure 14.4).

The fossa points laterally and slightly forward and articulates with the head of the humerus in anatomical position.

This is properly the socket of the ball and socket joint of the shoulder. In fact, glene is the Latin for ‘socket’.

Question 18

Humerus – The long bone of the upper arm is the humerus. It is a relatively infamous bone, being one of the critical elements – the crossed bones – of the original ‘Jolly Roger’ pirate flags of the late 17th century. Simple visual inspection tells you, yes, this is a long bone as it runs from the acromion down to the point of the elbow joint. Much of the bone is easily palpable but as with the scapula, the small features of the humerus may be less or more difficult to palpate and identify depending on the degree of individual muscularity.

Answer 18

Humerus possesses

• a proximal rounded head with a narrowed neck and two tuberosities. The greater tuberosity is the superior process appearing just lateral to the humeral head.
• The lesser tuberosity is slightly inferior, anterior and medial to the greater tuberosity. It is also palpable. A relevant landmark for locating the lesser tuberosity is the coracoid process. The tuberosity lies approximately and inch or two lateral to the coracoid process on the anterior surface of the upper arm at the shoulder. It is also anterior and inferior to the acromion. Rotation of the relaxed arm (hanging by the side) inward and outward several times will feel as a hard bump moving left to right under the skin and deltoid muscle (Figure 14.10).
• Both the greater and lesser tuberosities are important sites of shoulder muscle attachment. The distal end, discussed in more detail in the following topic, features two epicondyles, two processes (trochlea and capitulum), and three fossae (radial fossa, coronoid fossa, and olecranon fossa). Its body, or shaft, is roughly rounded towards the proximal, upper, portion then transitions to a more three-edged prismatic shape distally.

Question 19

Deltoid tuberosity:
Occurring along the lateral aspect of the humeral shaft. This low rising process will vary in degree of prominence on different individuals and heavy musculature may also make palpation difficult. On a skeletal model it is a moderately sized raised area that appears to be a little rough. This makes it an excellent representation of form facilitating function. Here, the elevation and rough surface texture provides an excellent means for muscle attachment. This bony feature is located at the bottom of the deltoidus muscle. Simply trace the line of the triangle-shaped deltoid muscle (shoulder muscle) down to its narrow inferior and lateral terminus on the humerus to a lateral point between the anterior biceps brachii and posterior triceps brachii muscles (bi’s and tri’s to the layman). This palpation may require a bit of pressure. A relaxed arm is important for palpation as contraction of any of the three muscle groups involved will prevent palpation with low manual pressure.

Answer 19

Uh oh

Question 20

Sternoclavicular joint

The articulation of the sternum and the clavicle is logically called the sternoclavicular joint. It is commonly thought that this joint is quite static, but it can move. Place a thumb on the manubrium, lateral to the suprasternal notch, and a finger somewhere along the length of clavicle. Movement of the shoulder anterior-posterior or superior-inferior through the complete range of motion will demonstrate the mobility of the clavicle relative to the manubrium. There is a joint capsule present along with a disc of cartilage within the capsule that contributes to joint stability. The costoclavicular ligament along with the sternoclavicular ligament stabilize the joint. The sternoclavicular ligament crosses the sternoclavicular joint from anterior and posterior.

Answer 20

Acromioclavicular joint
The articulation between the acromion process and the lateral and distal end of the clavicle. Frequently referred to as the AC joint, it is the joint at the top of the shoulder. The architecture of the acromioclavicular joint provides for a relatively unstable joint, more so than the sternoclavicular joint. This is not detrimental in any way given the high mobility requirements of shoulder joint for function. It is possible in some individuals to find the acromioclavicular ligament with careful palpatio. To find this jonint, walk the fingers of one hand laterally along the superior surface of the clavicle while walking the fingers of the other hand laterally along the scapular spine. Both hands should meet at the joint where the lateral end of the clavicle and acromion process articulate. The ligament lies between the two bones. The last major ligaments of interest, the coracromial and trapezoid ligaments, connect the coracoid process to the clavicle and provides further stability for the shoulder.

Question 21

Sternoclavicular joint

The articulation of the sternum and the clavicle is logically called the sternoclavicular joint. It is commonly thought that this joint is quite static, but it can move. Place a thumb on the manubrium, lateral to the suprasternal notch, and a finger somewhere along the length of clavicle. Movement of the shoulder anterior-posterior or superior-inferior through the complete range of motion will demonstrate the mobility of the clavicle relative to the manubrium. There is a joint capsule present along with a disc of cartilage within the capsule that contributes to joint stability. The costoclavicular ligament along with the sternoclavicular ligament stabilize the joint. The sternoclavicular ligament crosses the sternoclavicular joint from anterior and posterior.

Answer 21

Acromioclavicular joint
The articulation between the acromion process and the lateral and distal end of the clavicle. Frequently referred to as the AC joint, it is the joint at the top of the shoulder. The architecture of the acromioclavicular joint provides for a relatively unstable joint, more so than the sternoclavicular joint. This is not detrimental in any way given the high mobility requirements of shoulder joint for function. It is possible in some individuals to find the acromioclavicular ligament with careful palpatio. To find this jonint, walk the fingers of one hand laterally along the superior surface of the clavicle while walking the fingers of the other hand laterally along the scapular spine. Both hands should meet at the joint where the lateral end of the clavicle and acromion process articulate. The ligament lies between the two bones. The last major ligaments of interest, the coracromial and trapezoid ligaments, connect the coracoid process to the clavicle and provides further stability for the shoulder.

Question 22

Trapezius – The trapezius, also called the spinotrapezius, is the large and recognizeable superficial muscle of the upper back. Its geometric shape is roughly trapezoidal and thus the source of the muscle’s name. It extends vertically from as high as the occipital bone and occipital protuberance to as low as all of the thoracic vertebrae. It spans laterally from the vertebral processes out to the spine of the scapula.
Superior trapezius elevates the scapulae and therefore the shoulders (makes you shrug).
Middle trapezius pulls the scapula towards midline – retracts them.
Lower trapezius draws the scapulae downward – depresses them.

Answer 22

Deltoid – The deltoid is a moderately large, delta shaped muscle lying over the glenohumeral joint. The muscle attaches to several skeletal features and each attachment is associated with a distinct segment of the muscle. The anterior segment of the muscle proximally attaches at the inferior lateral third of the clavicle. The medial segment attaches proximally at the superior surface of the acromion process. The posterior segment attaches proximally along the entire length of the inferior scapular border. All three segments attach distally to the deltoid tuberosity of the humerus. For example the anterior deltoid is heavily recruited in the flexion of the humerus to the anterior along the sagittal plane, the medial segment contributes some to this movement, and posterior segment contributes even less to the movement.

Question 23

Trapezius – The trapezius, also called the spinotrapezius, is the large and recognizeable superficial muscle of the upper back. Its geometric shape is roughly trapezoidal and thus the source of the muscle’s name. It extends vertically from as high as the occipital bone and occipital protuberance to as low as all of the thoracic vertebrae. It spans laterally from the vertebral processes out to the spine of the scapula.
Superior trapezius elevates the scapulae and therefore the shoulders (makes you shrug).
Middle trapezius pulls the scapula towards midline – retracts them.
Lower trapezius draws the scapulae downward – depresses them.

Answer 23

Deltoid – The deltoid is a moderately large, delta shaped muscle lying over the glenohumeral joint. The muscle attaches to several skeletal features and each attachment is associated with a distinct segment of the muscle. The anterior segment of the muscle proximally attaches at the inferior lateral third of the clavicle. The medial segment attaches proximally at the superior surface of the acromion process. The posterior segment attaches proximally along the entire length of the inferior scapular border. All three segments attach distally to the deltoid tuberosity of the humerus. For example the anterior deltoid is heavily recruited in the flexion of the humerus to the anterior along the sagittal plane, the medial segment contributes some to this movement, and posterior segment contributes even less to the movement.

Question 24

PECTORALIS MAJOR – The pectoralis major is likely one of the two most recognized muscles in the body. For good or ill a huge number of adolescent and adult males think that having big pectoralis major muscles is the ultimate signature of masculinity. It is an important muscle of the shoulder joint, but attitudes towards big ‘pecs’ in men is an artificial social construct, barely 70 years old, driven by the evolution of comic book superheros and Hollywood leading men.

Answer 24

PEC MAJOR:
The pectoralis major is a two segment muscle with the both segments sharing a common distal attachment to the lateral lip of the bicepital groove just inferior to the greater tuberosity (Figure 14.19). The clavicular portion (pars clavicularis) attaches proximally to the inferior and medial half of the clavicle. This clavicular segment is superior and represents the smaller of the two segments. The sternal segment (pars sternalis) represents the bulk of the muscle, attaching proximally along the upper two thirds of the lateral border of the sternum. Both segments also have minor tendinous connections to the ribs near their major proximal attachments. Identification and palpation of the pectoralis major is easy. Flex the shoulder joint to the anterior at 90 degrees along the sagittal plane then adduct the humerus (the function of the pectoralis major) against resistance. An easy way to do this is to place the palms together, move the upper arm up parallel to the floor, and push towards the middle. Repeat this with the humerus at 10 degrees (forearms just in front of abdomen) and at 30 degrees (elbows at about the same level as the areola). At 90 degrees the clavicular segment is more dominant. At 30 degrees of humeral angle you will find relatively even recruitment. This simple observation should suggest that for optimal muscle recruitment, this is the angle of choice for use with exercises such as the bench press. This angle provides a favorable range of motion for maximal muscle movement and recruitment, this does not mean this is the best angle for powerlifting performance where moving as much weight as possible through the minimal legal distance is the goal.

Question 25

Biceps brachii – It will come as a surprise to many that the most recognizable ‘arm’ muscles, the ones that flex the elbow, are actually shoulder muscles too. The biceps brachii do act distally to flex the elbow (considered in the following topic), but they also act proximally relative to their frequently ignored attachments to the scapula. The short head of the biceps brachii attaches proximally to the anterior point of the coracoid process and distally to the radial tuberosity (on the radius bone of the forearm), thus crossing two joints. This means that the short head of the biceps can, if the hand is held static, pull the scapula up and/or tilt it to the anterior.

Answer 25

Coracobrachialis – The coracobrachialis is a small muscle that attaches proximally at the anterior point of the coracoid process (one of three to do so) and distally to the medial surface of the humerus – opposite to the deltoid tuberosity (Figure 14.20). The origin of the name of the coracobracialis is derived from its attachments on the coracoid process (the arm) and on the brachium. It functions to flex and adduct the humerus. If someone is lean enough, placing one’s arm parallel to the floor and attempting horizontal adduction should enable the muscle’s small mass palpation on the inner aspect of the upper arm at the axilla (armpit) in between the biceps and triceps

Question 26

Pectoralis minor – The pectoralis minor attaches proximally to the upper and outer aspect of the 3rd, 4th, and 5th ribs. It lies underneath the pectoralis major and runs to the superior and medial side of the coracoid process of the scapula, its distal attachment (Figure 14.20). Its deep position relative to the pectoralis major prevents its palpation. Contraction of the pectoralis minor pulls the scapula down and forward to a small degree

Answer 26

Latissimus dorsi – Although many people think of the latissimus dorsi as a very broad (latissimus means ‘broadest’ in Latin), very large superficial muscle of the mid- to low back, the one giving the upper body its ‘V’ shape, it is a very strong contributor to shoulder function. In fact, it carries out five movement roles at the shoulder, some more important than the others: extension, adduction, horizontal abduction, flexion from an extended position, and internal rotation. The muscle also contributes to extension and lateral flexion of the lumbar vertebrae. It is located lateral and inferior to the trapezius. It has multiple proximal attachments on the lower back including the lower four ribs (lateral and posterior aspect), the vertebral column from the sacrum up to the mid-thoracic level, a very small attachment at the inferior angle of the scapula, and on the posterior crest of the ilium. The latissimus dorsi passes under the axilla (armpit) around the humerus to the anterior and distally attaches along the bicepital groove between the pectoralis major and teres major.

Question 27

Triceps brachii – The triceps brachii is a three headed muscle, each head arising from different origins and joining together as the heads approach the elbow. The triceps suffer from the same linguistic singular-plural problem as the biceps. The long head of the triceps brachii attaches proximally to the scapula, along the lateral border immediately inferior to the glenoid fossa and distally to the ulna at the olecranon process (the point of the elbow) (Figure 14.23). The long head of the triceps brachii can and does contribute to the muscle group’s distal function of elbow extension. If the arm is held static, contraction of the long head can also pull the scapula down and lateral. However, its proximal attachment to the scapula gives it another overlooked proximal function, the scapula held stable and the humerus being adducted.

Answer 27

Serratus anterior – The serratus anterior has a characteristic saw-tooth appearance with several visible and distinct segments attaching proximally to the upper eight ribs and distally to the anterior medial surface of the scapula along its inferior border (Figure 14.24). The serratus rotates the inferior angle of the scapula, protracts the scapular laterally around towards the front of rib cage, and also isometrically holds the scapula in close proximity to the posterior aspect of the ribs. Individuals who box or do lots of push-ups will display well developed serrati muscles. Palpation is fairly easy. With the arm abducted or flexed overhead, providing a resistance at the elbow (stand in front and pushing gently backwards) will cause a serratus anterior contraction. The muscle then can be palpated with the flat of the four fingers down along the mid-axillary line (arm-pit and down). During most contractions of the serratus anterior, the ribs will be more stable than the scapula (less potential for mobility). As such, the scapula will move along the line of action dictated by the orientation of the muscle fibers. An exception to this occurs with any exercise or sporting activity involving suspension of the body by the hands and arms – chins, rope climbing, certain gymnastic movements, for example. In suspension, the scapula will be the most stable structure in the system and the serratus anterior muscles will be used to assist in elevating the thoracic segment of the body towards the scapula/arm/hand/apparatus system.

Question 28

Rhomboideus – The rhomboideus has two sections (major and minor) that appear, as the rhombus prefix would suggest, in a roughly diamond shape. The minor is smaller and superior to the major. Although there are two distinct muscles, they function as a single unit. Located beneath the lower trapezius segments and non-palpable, the rhomboideus minor muscle attaches proximally to the spinous processes of the seventh cervical vertebra along with the first and second thoracic vertebrae. The rhomboideus major attaches proximally to the spinous processes of the second, third, fourth, and fifth thoracic vertebrae. Both the major and minor attach distally to the medial border of the scapula at about the level of the scapular spine, with the major’s attachment extending well down to the scapula’s inferior angle (Figure 14.25). Contraction of the rhomboideus will generally cause retraction of the scapulae (pulling them closer to the midline of the body – or squeeze the shoulder blades together). The rhomboid major helps to hold the scapula (and thus the upper limb) onto the ribcage. It also acts to downwardly rotate the scapula, with respect to the glenohumeral joint and works synergistically with the levator scapulae to elevate the medial border of the scapula.

Answer 28

Levator scapula – The levator scapula is a muscle found deep and inferior to the trapezius (Figure 14.26). It attaches proximally to the transverse processes of the atlas, axis, third and fourth cervical vertebrae. Distally it attaches to the superior medial scapular border. This is a load bearing muscle that elevates the medial scapula and as such it will fatigue during activities like backpacking or carrying heavy loads as in the Farmer’s Walk. It is not palpable due to the overlying trapezius.

Question 29

Supraspinatus – The name provides a clue to the muscle’s location, above a spin. It lies above the scapular spine with its proximal attachment along the curvature formed by the spine and the body of the scapula superior to the spine. This depression on the body of the scapula is called the ‘supraspinous fossa’. The muscle attaches distally to the greater tuberosity of the humerus at its most superior point. This superior attachment means it is able to generate very little torque around the joint. The distal tendon passes beneath the acromion and superior to the glenohumeral joint. Its position relative to the joint makes it an abductor, but its small size limits its contribution to movement in only about the first 15 degrees of abduction. After that point, the co-contracting deltoideus assumes more of a dominant role in abduction of any load and the supraspinatus is relegated to an essentially isometric stabilization role. The supraspinatus is covered by the overlying superior segments of the trapezius and is thus too deep to be palpated.

Answer 29

Infraspinatus – The name infraspinatus gives us another excellent idea of this muscle’s location. It is inferior to the scapular spine, along the infraspinous fossa. The spine of the scapula separates the supraspinous and infraspinous fossae. It attaches distally to the greater tuberosity of the humerus. The infraspinatus is an external rotator of the glenohumeral joint and assists in abduction of the arm. However, as with the supraspinatus, its relatively small size and its very short lever arm on the humerus means that the muscle is capable of producing very little torque around the joint and will act primarily as a stabilizer.

Question 30

Teres major – The teres major is a fairly small muscle that lies superior and approximately parallel to the latissimus dorsi, lateral to trapezius and inferior to the posterior deltoid. It attaches proximally near the posterior inferior angle of the scapula and runs under the axilla and attaches distally on the anterior surface of the humerus, at the bicepital groove medial to the distal attachment of the latissimus dorsi. The teres major carries out similar functions to the latissimus; a medial humeral rotator, an adductor of the humerus, and a synergist with the latissimus dorsi in pulling a previously elevated humerus down and back (active in the pullover barbell exercise). Given its small size and poor leverage position, it is not a large contributor to forceful humeral movement, rather it acts with the latissimus dorsi to stabilize the humeral head in the glenoid fossa. The teres major can be visualized on lean individuals using the same approach as in identifying the latissimus dorsi, with the exception that the muscle is traced back to the scapula, not the iliac crest. If larger amounts of subcutaneous fat tissue is present palpation is the only means of identification.

Answer 30

Teres minor – Again, the name should indicate to us that this muscle is not too far from teres major. It is, in fact, located just superior to the teres major. The teres minor attaches proximally from just below the glenoid fossa then downwards about two thirds of the way along the lateral border of the scapula. As the muscle approaches the axilla, it passes posterior to the shoulder joint and attaches distally to the greater tuberosity, just lower than the attachments of the supraspinatus and infraspinatus. The teres minor functions to pull the humeral head into the glenoid fossa and to externally rotate the head of the humerus to the posterior. Both the teres minor and infraspinatus may be palpable on a well-developed or lean individual. With strong horizontal abduction and outward rotation of the humerus, you can generally find these muscles in relation to a triangle formed by the inferior line of the posterior deltoid, the lateral border of the trapezius, and a line formed by the superior aspects of the teres major and latissimus dorsi. The teres minor arises on the axillary border of the scapula and is lateral to the infraspinatus.

Question 31

Subscapularis – Sometimes this muscle is confused with the infraspinatus, but breaking down the name into its roots makes the location of the muscle easily distinguishable. The prefix ‘sub’ means lying below or under. ‘Scapularis’ refers obviously to the scapula so the subscapularis lies under the scapula in the space between it and the underlying rib-cage. This location, and the fact that its distal elements are under the deltoid, means that the muscle is not palpable. The subscapularis attaches proximally across the majority of the anterior and inferior surface of the scapula, the medial and lower two thirds of the scapula’s anterior surface. It is a broad and roughly triangular shaped attachment that thins as it approaches the axilla. The muscle attaches distally on the lesser tuberosity of the humerus. This anterior attachment results in internal rotation of the humeral head during contraction. This is a moderately large muscle that can produce a significant amount of tension drawing the head of the humerus into the glenoid fossa, thus serves as a stabilizer of the shoulder and defense against dislocation.

Answer 31

SHOULDER MOVEMENTS Adduction of the scapula is their movement towards the vertebral column. Sometimes called retraction. A layman’s description might be squeezing the shoulder blades together. Abduction is the movement of the scapula away from the vertebrae. A layman’s description might be rolling or rounding your shoulders forward. Elevation is the drawing of the scapulae in a superior, upwards direction. The common description of this is a shrug of the shoulders. Depression is the pulling of the scapulae in an inferior, downwards direction. This can be accomplished by getting someone to lift their chest and pull their shoulders straight down. Upward rotation is usually defined as a movement around a sagittal axis that passes through the center of the scapula, however, in actuality scapular movement does not occur around an axis at the geographic center of the scapula, it rotates around a point just inferior to the scapular spine and a few centimeters medial to the middle of the complete length of the spine. Upward rotation occurs when the inferior angle of the scapula moves to point more laterally, usually accompanying humeral abduction. Downward rotation is again usually defined as a movement of the scapula and inferior angle of the scapula around a central axis towards the anatomical midline. The movements of which the glenohumeral joint is capable of are abduction, adduction, flexion, extension, and rotation. These movements can occur in any plane within which the shoulder joint is capable of movement. They can occur singly or in combination. If the arm is raised directly in front of the body (from anatomical position), the shoulder is flexed. If the arm is raised to the rear, it is extended. Raised laterally to the side, it is abducted. Raised across the front of the body, it is adducted. If one starts at anatomical position and raises the arm forward, at the same time moves the thumb to point at the floor, while also moving the angle of the humerus to parallel to the frontal plane, simultaneous flexion, abduction, and rotation has occurred at the shoulder joint assembly. Multi-axial joint movements can be very complex and require a great deal of neural synchrony and coordination, this is another reason that exercises that involve more musculature and that are not artificially restricted (restricted as in exercise machines) are the most effective and beneficial ways to exercise.

Question 32

Tendonitis – An over-use injury as in tennis elbow, golfer’s elbow, archer’s elbow, and others. More precisely called epicondylitis and can occur as chronic pain and inflammation on either the lateral (as in tennis) or medial side (as in golf). Dislocation – The disarticulation of one or more of the bones of the elbow. Only about 6 persons per 100,000 will get an elbow dislocation each year. Fracture – A break in one of the bones of the joint at a point proximal to the joint. Generally occurring as a result of a fall or other forceful contact.

Answer 32

Humerus – The distal end of the humerus has a unique set of bony features providing for articulation with the radius and ulna. The trochlea is the roughly hour-glass shaped feature on the distal end of the humerus and articulates with the trochlear notch of the ulna. The head of the radius articulates with the capitulum of the humerus, the ball shaped feature just lateral to the trochlea. The trochlea and capitulum are the rounded, smooth, knuckle-like surfaces at the anterior and distal end of the humerus. It is around these structures that the elbow flexes and extends. There are two outcroppings of bone flanking the trochlea and the capitulum. The medial epicondyle and lateral epicondyle (of the humerus) are just proximal, lateral, and superior to the trochlea and capitulum. It may seem odd to have epicondyles present when there are no structures called condyles observed, as was seen at the knee. But condyles really are present here. Condyles are knuckles or rounded projections, and the trochlea and capitulum are condyles, they just have names. The epicondyles can be found by palpating the widest points of the distal humerus. The thumb and forefinger can generally span the elbow joint at its widest point from the posterior (Figure 15.2). The epicondyles should be evident as two superficial bony bumps extending from the distal and widest point and upwards as they narrow into the shaft of the bone. The narrowing represents the supracondylar ridges, extending from the epicondyle upward along the lateral and medial borders of the humerus. The medial epicondyle will be larger than the lateral.

Question 33

Ulna – The ulna is a long prismatic shaped bone found on the medial side of the forearm (pinky side). The proximal end of the bone is the thickest, narrowing to a near point as it approaches the wrist. The proximal end of the ulna features the prominent bony process, the olecranon process, or point of the elbow. It can be palpated in its position between and inferior to the epicondyles, most easily when the elbow is flexed (bent) (Figure 15.3). On the anterior side of the ulna, the trochlear notch is found. The trochlea of the humerus fits nicely into this fairly deep ‘c’ shaped notch. Just anterior to the notch is the coranoid process. The depth and width of these latter two features provide additional support to the elbow’s architecture. On the flip side of the distal humerus (posterior) there is a fairly significant depression called the olecranon fossa. The anterior end of the ulna fits snugly into this depression when the arm is straight (elbow extended). This provides a great deal of stability to the extended joint and a means of protection from hyperextension. It also creates a very hard physical limit to the range of motion of the elbow in extension.

Answer 33

Radius – The third bone of the system is the radius, the smallest of the elbow. The radius runs from the elbow down to the wrist on the thumb side. It is a long bone, curved along its length, and crudely prismatic in shape. The radial head, at the proximal end of the radius, articulates with the capitulum of the distal humerus and is just inferior to the lateral epicondyle. The ball shape of the capitulum and the nail-head looking radial head comprise a nicely designed pivot joint – the head of the radius rotates on the ball of the capitulum. Careful palpation just medial and inferior to the lateral epicondyle followed by rotation of the hand should reveal a bump that appears with inward rotation and disappears with outward rotation, the radial head. The most important bony feature relevant to the elbow is the radial tuberosity. A number of muscles of the elbow attach to it.

Question 34

Tendonitis – An over-use injury as in tennis elbow, golfer’s elbow, archer’s elbow, and others. More precisely called epicondylitis and can occur as chronic pain and inflammation on either the lateral (as in tennis) or medial side (as in golf). Dislocation – The disarticulation of one or more of the bones of the elbow. Only about 6 persons per 100,000 will get an elbow dislocation each year. Fracture – A break in one of the bones of the joint at a point proximal to the joint. Generally occurring as a result of a fall or other forceful contact.

Answer 34

Humerus – The distal end of the humerus has a unique set of bony features providing for articulation with the radius and ulna. The trochlea is the roughly hour-glass shaped feature on the distal end of the humerus and articulates with the trochlear notch of the ulna. The head of the radius articulates with the capitulum of the humerus, the ball shaped feature just lateral to the trochlea. The trochlea and capitulum are the rounded, smooth, knuckle-like surfaces at the anterior and distal end of the humerus. It is around these structures that the elbow flexes and extends. There are two outcroppings of bone flanking the trochlea and the capitulum. The medial epicondyle and lateral epicondyle (of the humerus) are just proximal, lateral, and superior to the trochlea and capitulum. It may seem odd to have epicondyles present when there are no structures called condyles observed, as was seen at the knee. But condyles really are present here. Condyles are knuckles or rounded projections, and the trochlea and capitulum are condyles, they just have names. The epicondyles can be found by palpating the widest points of the distal humerus. The thumb and forefinger can generally span the elbow joint at its widest point from the posterior. The epicondyles should be evident as two superficial bony bumps extending from the distal and widest point and upwards as they narrow into the shaft of the bone. The narrowing represents the supracondylar ridges, extending from the epicondyle upward along the lateral and medial borders of the humerus. The medial epicondyle will be larger than the lateral. The distal point of attachment of the deltoid muscle onto the humerus is the deltoid tuberosity. Bicipital groove on the anterior surface contains the tendon of the long head of the biceps

Question 35

Ulna – The ulna is a long prismatic shaped bone found on the medial side of the forearm (pinky side). The proximal end of the bone is the thickest, narrowing to a near point as it approaches the wrist. The proximal end of the ulna features the prominent bony process, the olecranon process, or point of the elbow. It can be palpated in its position between and inferior to the epicondyles, most easily when the elbow is flexed (bent). On the anterior side of the ulna, the trochlear notch is found. The trochlea of the humerus fits nicely into this fairly deep ‘c’ shaped notch. Just anterior to the notch is the coranoid process. The depth and width of these latter two features provide additional support to the elbow’s architecture. On the flip side of the distal humerus (posterior) there is a fairly significant depression called the olecranon fossa. The anterior end of the ulna fits snugly into this depression when the arm is straight (elbow extended). This provides a great deal of stability to the extended joint and a means of protection from hyperextension. It also creates a very hard physical limit to the range of motion of the elbow in extension.

Answer 35

Radius – The third bone of the system is the radius, the smallest of the elbow. The radius runs from the elbow down to the wrist on the thumb side. It is a long bone, curved along its length, and crudely prismatic in shape. The radial head, at the proximal end of the radius, articulates with the capitulum of the distal humerus and is just inferior to the lateral epicondyle. The ball shape of the capitulum and the nail-head looking radial head comprise a nicely designed pivot joint – the head of the radius rotates on the ball of the capitulum. Careful palpation just medial and inferior to the lateral epicondyle followed by rotation of the hand should reveal a bump that appears with inward rotation and disappears with outward rotation, the radial head. The most important bony feature relevant to the elbow is the radial tuberosity. A number of muscles of the elbow attach to it.

Question 36

Biceps brachii – The biceps brachii attach proximally on the coracoid process (long head) and near the glenoid fossa (short head) then attach distally at the radial tuberosity. This attachment to the radial tuberosity is of interest functionally. The proximal function of the biceps brachii has previously been covered. If the shoulder is held stable, a distal function is then revealed, simple flexion at the two humeral articulations of the elbow. What is frequently not considered is that the biceps brachii, by virtue of the attachment to the radial tuberosity, has an even more distal function, internal rotation (pronation) of the hand. This is accomplished by pulling the radius up and over the ulna at the radioulnar joint.

Answer 36

Brachioradialis – The brachioradialis has a proximal attachment to the lateral epicondyle and supracondylar ridge of the humerus and a distal attachment to the radial styloid process (the point of the distal end of the radius). The muscle flexes the elbow, however it is small and is not a strong force producer. Rather it has its role as a pronator or supinator of the wrist and hand – it can do either depending on the rotational position of the hand – that is its major function. Palpation of the brachioradialis is elementary, as it is quite superficial and readily visible and palpable on the thumb side of the forearm. Pronating the hand until it is in a ‘thumbs up’ position than flexion of the elbow up against a resistance will make the muscle palpable. The muscle would be a contributor to elbow flexion while the palms face each other such as in lifting a pot, or if considered singly when lifting a mug.

Question 37

Brachialis – Another flexor of the elbow, the brachialis (sometimes called the brachialis anticus) stretches from the anterior lower half of the shaft of the humerus down to the proximal end of the anterior ulna and its coronoid process. The brachialis, like the biceps brachii, is a strong flexor of the elbow. However given its attachment sites, closer to the elbow, it is at a mechanical deficit compared to the biceps and generates less of a motive force in flexion. This muscle does lie beneath the biceps brachii but its medial aspect is palpable. Supination of the forearm and flexion of the arm against resistance will make the muscle belly rigid when the fingers are placed on both sides of the biceps tendon.

Answer 37

Supinator – The supinator is a deep muscle of the elbow, attaching proximally to the lateral epicondyle of the humerus and distally to the lateral aspect of the radial tuberosity and along the body of the bone a short distance. Although it crosses the elbow, its size and orientation provides little ability to produce flexion, rather it acts as its name implies, as a supinator rotating the radius laterally.

Question 38

OTHER ELBOW LIGAMENTS The oblique cord: angles across the space between the proximal ulna at the base of the coranoid process to the proximal radius just inferior the radial tuberosity. The ligament helps prevent the separation of the two bones, limits rotation, and may actually reinforce bone structure and help prevent bending. Another component of the multiple connections between the radius and ulna is the interosseous membrane. This is a sheet of fibrous connective tissue that runs diagonally between the radius and ulna. Much like the oblique cord, it maintains the integrity of the proximal radioulnar joint (it serves the same purpose for the distal radioulnar joint). It functions to prevent separation of the two bones, redistributes forces applied to the radius to the ulna, and resists asymmetrical longitudinal sliding along the longitudinal axis of the two bones.

Answer 38

The three major elbow ligaments are the 1- Radial collateral ligament on the lateral side, 2- Ulnar collateral ligament on the medial side 3- Annular ligament holding the head of the radius.

Question 39

Biceps brachii – The biceps brachii attach proximally on the coracoid process (long head) and near the glenoid fossa (short head) then attach distally at the radial tuberosity. This attachment to the radial tuberosity is of interest functionally. The proximal function of the biceps brachii has previously been covered. If the shoulder is held stable, a distal function is then revealed, simple flexion at the two humeral articulations of the elbow. What is frequently not considered is that the biceps brachii, by virtue of the attachment to the radial tuberosity, has an even more distal function, internal rotation (pronation) of the hand. This is accomplished by pulling the radius up and over the ulna at the radioulnar joint. The biceps brachii attach proximally on the coracoid process (long head) and near the glenoid fossa (short head) then attach distally at the radial tuberosity. This attachment to the radial tuberosity is of interest functionally. The proximal function of the biceps brachii has previously been covered. If the shoulder is held stable, a distal function is then revealed, simple flexion at the two humeral articulations of the elbow. What is frequently not considered is that the biceps brachii, by virtue of the attachment to the radial tuberosity, has an even more distal function, internal rotation (pronation) of the hand. This is accomplished by pulling the radius up and over the ulna at the radioulnar joint. bi's pronate the wrist as in screwdrivers

Answer 39

Brachioradialis – The brachioradialis has a proximal attachment to the lateral epicondyle and supracondylar ridge of the humerus and a distal attachment to the radial styloid process (the point of the distal end of the radius). The muscle flexes the elbow, however it is small and is not a strong force producer. Rather it has its role as a pronator or supinator of the wrist and hand – it can do either depending on the rotational position of the hand – that is its major function. Palpation of the brachioradialis is elementary, as it is quite superficial and readily visible and palpable on the thumb side of the forearm. Pronating the hand until it is in a ‘thumbs up’ position than flexion of the elbow up against a resistance will make the muscle palpable. The muscle would be a contributor to elbow flexion while the palms face each other such as in lifting a pot, or if considered singly when lifting a mug.

Question 40

Brachialis – Another flexor of the elbow, the brachialis (sometimes called the brachialis anticus) stretches from the anterior lower half of the shaft of the humerus down to the proximal end of the anterior ulna and its coronoid process. The brachialis, like the biceps brachii, is a strong flexor of the elbow. However given its attachment sites, closer to the elbow, it is at a mechanical deficit compared to the biceps and generates less of a motive force in flexion. This muscle does lie beneath the biceps brachii but its medial aspect is palpable. Supination of the forearm and flexion of the arm against resistance will make the muscle belly rigid when the fingers are placed on both sides of the biceps tendon.

Answer 40

Supinator – The supinator is a deep muscle of the elbow, attaching proximally to the lateral epicondyle of the humerus and distally to the lateral aspect of the radial tuberosity and along the body of the bone a short distance. Although it crosses the elbow, its size and orientation provides little ability to produce flexion, rather it acts as its name implies, as a supinator rotating the radius laterally.

Question 41

Pronator teres – The pronator teres attaches proximally to the medial aspect of the supracondylar ridge of the humerus and distally to the proximal end of the radius, down to about half way down its length. It crosses the elbow joint and can be considered an elbow flexor, but since it attaches medially to the medial epicondyle and laterally to the radial tuberosity, it is also a potent pronator of the hand. Palpation of the muscle is done through repeated pronation of the hand against resistance followed by unresisted supination. The pronator teres and the brachioradialis flank the biceps brachii tendon, medially and laterally respectively. The slight skin depression within the ‘V’ formed by the two muscles on the upper forearm is called the ‘cubital fossa’ – the area from which you usually get blood drawn.

Answer 41

Triceps brachii – The triceps brachii is morphologically as its name suggests, a muscle having three segments of the arm. There are three fascicles (bundles) of muscle making up the muscle body – the long, medial, and lateral head – each with a separate proximal attachment and a shared distal attachment (Figure 15.10). The long head, aptly named as it attaches proximally to the scapula, inferior to the glenoid fossa (as discussed in the shoulder topic), attaches distally via a shared triceps tendon to the olecranon of the ulna. The lateral head attaches proximally to the posterior humerus from an area just inferior to the greater tuberosity and down about a third the length of the shaft. The lateral and long heads are the most visible and palpable portions of the muscle. The medial head lies mostly under the lateral head, attaching proximally to the humerus along a narrow triangle stretching along the lower three fourths of the humerus. All three sections attach distally to the olecranon process of the ulna via a fusion into an elongated and central tendon. The long head has two functions as it crosses both the shoulder and elbow. The first being its proximal function at the shoulder, the second and common to all three heads of the triceps brachii is extension of the elbow joint.

Question 42

Anconeus – The anconeus is a small, roughly triangular muscle attaching proximally to the point of lateral epicondyle of the humerus and distally to the olecranon process and downwards a short distance. Its small size and unfavorable orientation to produce torque suggests that it is not a strong elbow extensor although it does assist. It can also function as a supinator and as a tension provider to keep the joint capsule taught thus preventing impingement. The anconeus may be palpable in the area between the lateral epicondyle and olecranon process with mild flexion of a hanging arm then gentle extension.

Answer 42

ELBOW MOVEMENTS

Question 43

The humeroulnar and humeroradial joints are hinge joints and are capable of flexion and extension. Flexion involves the movement of the hand and forearm towards the shoulder via rotation around the joint. Extension at the humeroulnar joint is the opposite of flexion and is the movement of the hand and forearm away from the shoulder. The radioulnar joint rotates in two directions thus facilitating pronation and supination. Pronation is the inward rotation of the forearm and hand, putting the hand palm down. Supination is the outward rotation of the forearm and hand, putting the palm up.

Answer 43

In respect to whole body locomotion, the structure of the elbow generally reflects a sex-related difference. When the elbow is extended, the line of humeral identity is not shared with the radius and ulna. In anatomical position, the angle of the lower arm to the upper arm deflects away from the body, this is called the ‘carry angle’ (Figure 15.13). There is quite a range of normal angles, from as little as 3 degrees up to as many as 29 degrees. Women generally have a more acute (higher number) carry angle than men, a putative result of human development where the wider hips of women require such an angle to enable impediment free arm swing during walking. Cubitus Valgus = Term for an extreme angle away from normal. Cubitis Varus= An angle toward the body is called. Both, especially in severe cases, carry with them possible movement limitation and risk of injury in sport and exercise, but not to the extent to prevent participation in either.