Module 2 Clinical Anatomy Specific Objectives.pdf
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Clinical Anatomy 1. Describe the two major types of fascia (superficial and deep), their functions and general locations 2 Questions Fascia describes the tissue that wraps, packs, and insulates the deep structures of the body. Deep fascia is found underlying almost all subcutaneous...
Clinical Anatomy 1. Describe the two major types of fascia (superficial and deep), their functions and general locations 2 Questions Fascia describes the tissue that wraps, packs, and insulates the deep structures of the body. Deep fascia is found underlying almost all subcutaneous tissue (superficial fascia) in the body. Deep fascia is made up of dense regular connective tissue and is devoid of fat. Deep fascia can also have extensions from its surface that form the epimysium and neurovascular bundles among other things, these projections are known as investing fascia. This investing fascia can group muscles that share the same nerve supply into fascial compartments, and the investing fascia that forms them is termed intermuscular septa. The muscles will glide along the deep fascia; however, when contacting bone, the fascia will blend with the periosteum. Near certain joints like the wrist and ankle, deep fascia becomes thickened to hold the tendons in place where they cross the joint to prevent ‘bowstringing’ and is called a retinaculum. 2. Distinguish the three basic structural types of joints (fibrous, cartilaginous, synovial) 1 Question Joints are articulations (a place of union between two or more rigid components) Fibrous- These joints are united by fibrous tissue, and a syndesmosis is a specialized type of fibrous joint that unites the bones with a sheet of fibrous tissue (ligament or fibrous membrane) allowing motility. A gomphosis (dento-alveolar syndesmosis) is a type of fibrous joint in the teeth Cartilaginous- Are joints united by hyaline cartilage or fibrocartilage. Those joined by hyaline cartilage are called primary cartilaginous joints and allow for bone growth. They are also called synchondroses and can be considered “joined by cartilage”. Meanwhile, those joints joined by fibrocartilage are termed symphyses and are strong and slightly mobile, an example would the intervertebral discs. Synovial Joints- The articular cavity of synovial joints are potential spaces that contain small amounts of synovial fluid. This fluid serves to both nourish the cartilage and lubricate the joint surfaces. They are the most common type of joint. They are typically reinforced with accessory ligaments that can be either separate (extrinsic) or part of (intrinsic) parts of the joint capsule. The joints can also have things like fibrocartilaginous articular discs when the bones are incongruent 3. Describe the four basic types of bony features (elevation, depression, opening, space) and list examples of each types (e.g. tubercle, fossa, foramen, cavity) 1 Question Elevation- As the name suggests, is a protrusion from the bone in an upward direction. An example of an elevation would be the spinous process of the vertebrae. A tubercle, such as the greater tubercle of the humerus, is also a type of elevation Depression- In contrast, a depression is an ‘indent’ into the bone surface. A fossa is an example of this type of hollow/depressed area (i.e., infraspinous fossa of the scapula) Opening- An opening is a passage in the bones that allows travel of things like nerves and arteries. Foramen is a term used to describe these openings and foramina can be found all over the body. Space- A space is a hollow region found within the bone and can be described as a cavity. An example of a cavity would be the medullary cavity, found in bone shafts, it is the storage space for red/yellow marrow. 4. Identify the parts of typical and atypical vertebra (including on radiographs) and describe the features of each regional type 2 Questions The vertebrae vary in size and in characteristics from one section of the column to another. The typical vertebrae have superior and inferior notches of adjacent vertebrae that form the intervertebral (IV) foramina, which gives passage for rami and roots and contain the spinal ganglia. The vertebral foramina is the vertical passage in the articulated column that contains the spinal cord, meninges, fat, spinal root nerves, and vessels. A vertebral arch is typically the bony protrusion attached to the vertebral body and has 7 processes. It has one spinous process that projects posteriorly and along the median from the junction of the laminae, two transverse processes that project posterolaterally from the junctions of the pedicles and laminae, and four articular processes (two inferior/two superior) that also arise from the pedicle/laminae junction, and each has an articular surface (feet). The spinous and transverse processes provide attachment for the deep back muscles. The articular processes form zygapophysial (facet) joints. These joints are classified as synovial, plane joints. These joints allow for gliding movement between the articular processes. Cervical- The cervical vertebrae have 3 different variations. The C1 vertebra is also called the Atlas and the C2 vertebra is termed the Axis. C3-C7 are ‘normal’ cervical vertebrae. The Atlas has no vertebral body and instead has a foramen for dens to articulate, held in place by the transverse ligament of the Atlas. It also has lateral mass where the axis meets the atlas. The axis also lacks a true vertebral body and instead has a place where the dens projects from. The ‘peg and hole’ mechanism, as well as the articular facets of the Atlas and Axis allows for the rotation of the neck. All cervical vertebrae have a foramen transversarium where the vertebral artery passes through. This distinguishes C3-C7 from the other vertebrae in the column. Thoracic- The thoracic vertebrae span from T1-T12 and can be characterized by their costal facets, where the ribs attach. They can also be identified by their long, downward facing spinous processes. Lumbar- The lumbar vertebrae stretch from L1-L5 and are characterized as the largest and thickest of all the vertebrae. This is because they support much of the body’s weight and allow for flexibility/movement. Compositionally, the lumbar vertebrae are typical and lack the defining characteristics of the cervical and thoracic regions Sacral/Coccygeal- In adults, the sacrum is composed of five fused sacral vertebrae. The projecting anterior edge of the body of the first sacral vertebrae is called the sacral promontory. The pelvic and dorsal surfaces of have four pairs of sacral foramina where the first four sacral nerves of the parasympathetic system exit to form splanchnic nerves. The fused spinous processes form the median sacral crest, while the articular and tips of the transverse processes form the intermediate and lateral sacral crests, respectively. The sacral hiatus, shaped like an upside down U, leads to the sacral canal, which is the inferior end of the vertebral canal. The sacral cornua are inferior projections of the sacral hiatus. There is also the Sacro-iliac joint on the lateral surface of the sacrum. The four vertebrae of the coccyx are typically fused. 5. Describe the organization (bones, joints, ligaments), function, and movements of the vertebral column 1 Question The joints of the vertebral bodies are secondary cartilaginous joints (symphyses) designed for weight bearing and strength. The articulating surfaces of the vertebrae are connected by IV (intervertebral) discs and ligaments. The discs not only allow movement, but also possess the property of resilient deformability which allows for shock absorption. The discs are made up of anulus fibrosus (the outer fibrous part) and the nucleus pulposus (a gelatinous central mass). Note the absence of IV discs between the C1 (atlas) and C2 (axis) and that the lowest disc is between L5 and S1, because of the nature of the sacrum. Between the vertebrae C3-C6 lie the uncovertebral ‘joints’ of Luschka located between the uncus (cuts) of the vertebral bodies and the inferolateral surfaces of vertebral bodies superior to them. These ‘joints’ are the sight of spur formation and can cause neck pain. There are two major longitudinal ligaments that run along the vertebral column, the anterior and posterior longitudinal ligaments. The anterior ligament is a strong, fibrous ligament that covers and connects the anterolateral aspects of the vertebral bodies to the IV discs. They serve to limit the extension of the vertebral column. The posterior longitudinal ligament runs within the vertebral canal along the posterior side of the vertebral bodies. It serves to prevent hyperflexion of the vertebral column and posterior herniation of the discs. The laminae of adjacent vertebral arches are joined by a broad, pale, yellow elastic fibrous tissue called ligamenta flava which serves to resist vertebral separation by stopping abrupt flexion. Adjacent spinous processes are connected by (weak) interspinous ligaments and (strong) supraspinous ligaments. This supraspinous ligament merges with nuchal ligament, the strong median ligament in the neck (scruff). 6. Identify the surface anatomy and palpable bony landmarks used during the examination of the back region 1 Question The most prominent region in a typical back exam will be either the C7 or T1 spinous process (with the C7 being more common). The supracristal plane (high points of Iliac crests) crosses the L4/L5 spinous process. 7. Describe the major features of the spinal cord, meninges and meningeal spaces and their relationship within the vertebral canal 1 Question The spinal cord runs inside of the vertebral canal and is wrapped in a series of meninges, or protective layers of connective tissue. The origin of the spinal cord is just a continuation of the medulla oblongata (caudal part of brainstem). The spinal cord typically terminates between L2 and L3 in newborns and L1 and L2 in adults. There are also two enlarged regions, that correspond to the area where extra neuron cell bodies must be to account for innervation of the limbs. The cervical enlargement is the region of the spinal column where the upper limbs are innervated by the brachial plexus, which is formed from the anterior rami of the spinal nerves between C4 and T1. The lumbosacral (lumbar) enlargement is found between L1 and S3, and the anterior rami of this region form the lumbar and sacral plexuses which innervate the lower extremities. The spinal nerve roots of the lumbosacral enlargement and the tapered end of the spinal cord (conus medullaris) form the cauda equina, so named because of the horsetail like shape of the projection. The space the cauda equina is found is known as the lumbar cistern (subarachnoid space). At the end of the conus medullaris is the filum terminale internum, which is made of mostly pia mater and is found in the bundle of roots in the cauda equina. The filum terminale internum penetrates the inferior end of the dural sac (dura mater) and become the filum terminale externum that will pass through the sacral hiatus to reach the posterior end of the coccyx. The filum terminale is the anchor for the inferior end of the spinal cord and dural sac. 8. Identify the nerve root typically affected by herniated nucleus pulposus (intervertebral disc) at any given vertebral level in the cervical or lumbar spine 1 Question The general rule for the nerve root affected by a herniation of the nucleus pulposus is that the second nerve listed in the sequence is the nerve affected (i.e., the in an L3/L4 herniation, the L4 would be the nerve affected). Herniations often occur posterolaterally because the anulus is relatively thin in this position and the it does not receive structural support from the anterior or posterior longitudinal ligaments. This is the case in both the cervical and lumbar regions, though the mechanism is slightly different. In the lumbar spine the spinal nerve that exits the intervertebral foramina passes through the superior half of the foramen and therefore lies above the herniating disc at that level and is therefore unaffected. In the cervical region the second nerve in the sequence is affected because the nerve exits above the named vertebrae and the herniated disc compresses the nerve. 9. Name the major muscles of the back and describe their actions, innervations (dorsal vs ventral rami), and general attachments. Distinguish intrinsic vs extrinsic muscles 1 Question The muscles of the back be grouped into two major groups… Extrinsic back muscles- These are the back muscles that include superficial and intermediate muscles that produce and control limb and respiratory movements and are innervated by the anterior rami of the spinal nerves. While they are found in the back they are for all intents and purposes innervated and controlled by the same mechanisms as the front/upper extremities. Intrinsic back muscles- Known as muscles of the back proper or deep back muscles, these muscles are innervated by the posterior rami of the spinal nerves and function to maintain posture and control the movement of the vertebral column. The deep back muscles are further grouped into layers according to their relationship with the surface (deep, intermediate, and superficial). 10. List, in order, the structures and spaces pierced in a lumbar puncture and in epidural anesthesia 1 Question Lumbar puncture (Spinal tap) Skin→ Supraspinous Ligament→ Interspinous Ligament→ Ligamentum Flavum→ Dura Mater→ Arachnoid Mater *Should not pierce the Pia mater* Epidural Anesthesia Skin→ Supraspinous Ligament→ Interspinous Ligament→ Ligamentum Flavum *Should not pierce the Dura mater* 11. Describe how X-ray images are generated and explain the different tissue densities 1 Question X-ray images are generated by shooting penetrating x-rays through the patient and onto a detector. As this beam passes through the body, certain structures may reflect or absorb more of the x-rays, resulting in less hitting the detector, and a relatively light area on the image. Objects are said to be radiolucent/radiodense according to how permeable they are to x-ray beams. For example, air is highly radiolucent and less radiodense, while compact bone is said to be highly radiodense, but lacking radiolucidity 12. Describe how CT scans are generated and explain how axial images (of both CT and MRI) are viewed 3 Questions CT (computer topography) scans are essentially ‘super x-rays’ where the patient is placed in the CT machine and the x-ray tube and detector both rotate around the axis of the body. It generates radiographic images that resemble transverse anatomical sections. The absorption of the x-rays in CT scans follows the same rules as that of the x- ray. Axial images are viewed as if the patient is supine and the view is at their feet, viewing inferiorly. Note that this means that what you are viewing is a mirror image. 13. Describe the osteological features of the bones of the upper extremity 2 Questions The upper extremity can be divided into 4 major segments: Pectoral (shoulder) girdle- A bony ‘ring’ with an incomplete posterior portion formed by the scapulae and clavicles with the anterior portion completed by the manubrium of the sternum. Shoulder- Includes the deltoid, pectoral, scapular, and lateral part of the lateral cervical region. Arm- Is the portion of the upper extremity between the shoulder and the elbow, centered at the humerus. It is considered to have an anterior and a posterior region Forearm- Located between the elbow and the wrist, it contains the radius and ulna and is also said to have an anterior and posterior region. Hand- Distal to the forearm and is made up of the carpus, metacarpus, and phalanges -The clavicle (collarbone) connects the upper extremity to the trunk. It has a sternal end that will articulate with the manubrium of the sternum at the sternoclavicular (SC) joint, and an acromial end that will articulate with the acromion of the scapula at the acromioclavicular (AC) joint. -The scapula (shoulder blade) is a triangular shaped flat bone that sits on the posterolateral aspect of the thorax, on top of the 2nd through 7th ribs. The posterior surface of the scapula is unevenly divided by the spine of the scapula which splits the posterior surface into a supraspinous fossa (above the spine) and an infraspinous fossa (below the spine). The ribs sit on a concave costal surface on the anterior side of the scapula in a large subscapular fossa. The scapula is said to have a medial (axillary), lateral (vertebral), and superior border, as well as superior and inferior angles. The lateral border is the thickest part of the scapula and, superiorly, includes the head of the scapula where the glenoid cavity is located. The glenoid cavity articulates with the head of the humerus at the glenohumeral (shoulder) joint. Note that the head of the humerus is larger than the socket of the glenoid cavity meaning that there can be slippage (i.e., why the shoulder can dislocate so easily). The neck of the scapula is just medial to the head. The superior border of the scapula has a suprascapular notch that marks the junction of its medial two thirds and lateral third. The acromion is the subcutaneous point of the shoulder and a lateral continuation of the spine of the scapula. The coracoid process is beak-like and is superior to the glenoid cavity with its projection going anterolaterally. -The humerus (arm bone) is the largest bone in the upper extremity and articulates with the scapula at the glenohumeral (shoulder) joint and the radius and ulna at the elbow joint. The intertubercular sulus is at the proximal end of the humerus and separates the lesser and greater tubercles. Just distal to the head of the humerus is the anatomical neck of the humerus, this is different from the surgical neck which is found distal to the tubercles at the point that connects the shaft of the humerus. The shaft of the humerus has the deltoid tuberosity on the lateral side and the radial groove (a spiral groove for the radial nerve) on the posterior side. As you move towards the inferior end of the humerus, the shaft widens and medial and lateral supracondylar ridges form and then end distally in the medial and lateral epicondyle. The distal end of the humerus includes the trochlea, capitulum, olecranon, coronoid, and radial fossae which all come together to form the condyle of the humerus. The condyle has two articular surfaces, a lateral capitulum for articulation with the radius and the medial trochlea which articulates with the trochlear notch of the ulna. Superior to the trochlea is the coronoid fossa where the coronoid process of the ulna rests during extension of the elbow. On the posterior side, the olecranon fossa is where the olecranon of the ulna sits during extension. Superior (and anterior) to the capitulum is the (shallow) radial fossa where the head of the radius will be accommodated during flexion. -The ulna is the stabilizing bone of the forearm; it is longer than and medial to the radius. The proximal end has two major projections, the olecranon (posteriorly) and the coronoid process (anteriorly), which combined form the trochlear notch that articulates with the trochlear notch of the humerus. Inferior to the coronoid process of the trochlear notch is the tuberosity of the ulna, and lateral to the coronoid process is the radial notch (smooth, rounded concavity) where the radial head articulates. Distal to the radial notch is the tuberosity of the ulna, and distal to the coronoid process is the supinator fossa (a concavity). The shaft of the ulna is thick but tapers distally in diameter. At the narrow distal end of the ulna is the head with a small, conical styloid process. -The radius is the shorter of the two bones in the forearm. Its proximal end has a cylindrical head, a shorter neck, and a medial surface projection called the radial tuberosity. The radial tuberosity is the maker between the proximal end of the radius and the shaft. The head of the radius articulates proximally with the capitulum of the humerus, as well as medially with the radial notch on the ulna. The shaft of the ulna is laterally convex and enlarges in diameter as you go distally, in contrast to the ulna. The medial aspect of the distal end form the (concave) ulnar notch where the head of the ulna is accommodated. The lateral aspect of the distal end is the radial styloid process, which is larger than its ulnar counterpart and extends further distally (important in fractures). The dorsal tubercle serves a trochlea (pulley) for the tendon of the long extensor of the thumb. When viewing the hands/wrists note that all positional markers are taken relative to anatomical positioning, that is to say, that the thumb side will always be lateral, and the 5th finger (pinky) side will always be the medial side (palms face anteriorly in anatomical position). -The wrist (carpus) is made of 8 carpal bones (carpals) that are arranged into proximal (closer to the forearm) and distal (closer to the metacarpals) that give the wrist flexibility. Proximal from left to right (lateral to medial) Scaphoid- Boat-shaped with a scaphoid tubercle. Also has a waist on its midline that gets poor circulation and thus heals very poorly Lunate- Moon-shaped and broader anteriorly than posteriorly Triquetrum- Pyramidal bone on the medial aspect of the wrist Pisiform- Small pea-shaped bone that lies on the palmar surface of the triquetrum Distal from left to right (lateral to medial) Trapezium- Four-sided bone on the lateral side Trapezoid- Wedge shaped bone Capitate- Head-shaped, the largest in the carpus Hamate- Another wedge-shaped bone, has a hooked process called the hook of hamate that extends anteriorly The metacarpus forms bones that make up the palm of the hand and sit between the carpus and phalanges. It is made up of 5 metacarpal bones (metacarpals) that each have a base, a shaft, and a head. The 1st metacarpal is the thickest. The base articulates with the carpal bones, while the distal heads articulate with the proximal phalanges to form the knuckle. Each digit (except for the thumb) has 3 phalanges, a proximal, middle, and distal (the thumb only has proximal and distal). Each of the phalanges has a proximal base, a shaft, and a distal head. The distal phalanges have a head that is flattened and expanded to underline the nail beds. 14. Describe the venous and lymphatic drainage and arterial supply of the upper extremity 1 Question Venous/Lymphatic Drainage The superficial lymphatic vessels arise from the lymphatic plexuses of the skin of the fingers, palm, and dorsum and will (mostly) ascend with superficial veins (cephalic and basilic). Consequently, since they are following veins, the flow of lymph will go retrograde, and back towards the heart with an ultimate termination point at the axillary lymph node. Those lymphatic vessels that follow the basilic vein will drain first into the cubital lymph nodes that are located proximal to the medial epicondyle (elbow). The basilic vein will arise from the medial aspect of the dorsal venous network and ascend along the medial side of the forearm and the inferior portion of the arm. It runs superiorly and parallel to the brachial artery where it will merge with the branchial artery’s accompanying veins to form the axillary vein. There is also a vein that ascends the middle of the anterior aspect of the forearm called the median antebrachial cutaneous vein. (Most of) those lymphatic vessels following the cephalic vein will cross the proximal aspect of the arm and enter the apical lymph nodes at the anterior aspect of the shoulder. The cephalic vein itself will ascend from the subcutaneous tissue in the lateral aspect of the dorsal venous network along the lateral border of the wrist and the anterolateral surface of the forearm/arm. Additionally, anterior to the elbow, the cephalic vein will communicate with the medial cubital vein which will pass over the elbow, obliquely, and join the basilic vein. At its most superior aspect, the cephalic vein will join the terminal end of the axillary vein in the clavipectoral fascia (clavipectoral triangle). Both the cephalic and basilic superficial veins originate in the subcutaneous tissue on the dorsum of the hand to form the dorsal venous network. The connection between these superficial veins and the deep veins are called perforating veins. Deep veins are found deep in the fascia and are referred to as accompanying veins because they are typically found in pairs that are continually anastomosing (linking) and both travel with, and the bear the name of, the major arteries they are associated with. Arterial Supply The main blood supply of the upper extremity comes from the axillary artery, which itself can be said to be a continuation of the subclavian artery. The ‘border’ is said to be the lateral border of the 1st rib, that is to say anything proximal to it is considered the subclavian artery and the anything distal will be considered the axillary artery. The axillary artery will then ‘become’ the brachial artery at the inferior border of the teres major and will then itself split into the radial and ulnar arteries at the ends of the cubital fossa opposite the neck of the radius (just distal to the elbow joint). The brachial artery has a major branch known as the profunda brachii artery (the deep artery of the arm) that will travel in the radial groove to form the periarticular cubital anastomosis of the elbow. The ulnar artery will descend through the anterior compartment of the forearm. The radial artery will go down the forearm laterally deep to the brachioradialis, and it will leave the forearm by crossing the anatomical snuff box to reach the hand. All of the blood in the hand is provided by superficial and deep palmar arches via the ulnar and radial arteries. 15. Describe Colles and scaphoid fractures, including radiographs 1 Question A Colles fracture is a specific type of fracture in the distal 2cm of the radius and is the most common fracture in the forearm, often in those aged over 50. The distal fragment will be displaced dorsally and will often be broken into pieces (comminuted). The usual mechanism for fracture is putting one’s hands out to brace a fall, resulting in forced dorsiflexion. Can be called a dinner fork deformity because of the anterior curve found in a relaxed hand. Scaphoid fractures are often the result of a fall onto an abducted palm. If the fracture occurs along the waist of the scaphoid, then the fracture may be abnormally long due to poor blood supply to the area. In certain cases, avascular necrosis can occur in the scaphoid, and this will result in the onset of degenerative joint disease of the wrist. 16. Describe the extrinsic (superficial) muscles of the back and pectoral region in terms of their general attachments, innervations, and major actions 1 Question The extrinsic muscles of the back can be grouped into 2 major categories, the axioappendicular muscles (extrinsic shoulder) which attach the appendicular skeleton of the upper extremity to the axial skeleton of the vertebral column and act to move the scapula on the chest wall, and the scapulohumeral muscles (intrinsic shoulder) which attach the scapula to the humerus and act at the glenohumeral joint. Axioappendicular muscles- There are four anterior axioappendicular muscles, pectoralis major and minor, subclavius, and serratus anterior, and they function to move the pectoral girdle. The pectoralis major is fan shaped and has 2 heads, a clavicular and a sternocostal one. It will form the deltopectoral groove with the adjacent deltoid, where the cephalic vein will run. The triangular pectoralis minor lines the anterior wall of the axillary and is almost completely covered by the pectoralis major. It functions to stabilize the scapula and will also form a ‘bridge’ (with the coracoid process) that vessels/nerves will pass through to the arm. Subclavius is a small, rounded muscle, inferior to the clavicle, that will protect the subclavian vessels and the superior trunk of the brachial plexus, from clavicle fractures. Serratus anterior sits on top of the lateral part of the thorax and is the median wall of the axillary. It gets its name from a characteristic ‘saw-tooth’ like appearance of its muscle sheet. Its main function is to anchor the scapula and allow it to function as a fixed bone for humeral movement. Note that serratus anterior is innervated by the long thoracic nerve and if it is injured then the medial border of scapula will move laterally and posteriorly creating the condition known as ‘winged-scapula’. There are also 2 groups of posterior axioappendicular muscles (superficial extrinsic) that each have 2 unique muscles in them. The superficial posterior axioappendicular muscles (trapezius and latissimus dorsi) and the deep posterior axioappendicular muscles (levator scapulae and rhomboids). Scapulohumeral muscles- There are 4 major scapulohumeral muscles, supraspinatus, infraspinatus, teres minor, and subscapularis (the SITS muscles). These muscles can also be called rotator cuff muscles, because they form the rotator cuff that surrounds the glenohumeral joint. All of them, except for supraspinatus (abductor), are rotators of the arm. The tendons of the SITS muscles will blend with the joint capsule of the glenohumeral joint, making into a musculotendinous structure for protection and stability. This is especially important because of the larger nature of the humeral head, as compared to the glenoid cavity. Injury to the axillary nerve, such a surgical neck fracture of the humerus, could result in atrophy of the deltoid and subsequent weakness in shoulder abduction. 17. Describe the course and branches of the axillary artery and vein, and drainage pattern of axillary lymph nodes 2 Questions Note that the axilla refers to the pyramidal compartment inferior to the glenohumeral joint, the armpit. It can ‘change size’ depending on the level of abduction of the arm and is the passageway for a number of vessels and nerves. The axillary artery is a continuation of the subclavian artery and begins at the lateral border of the 1st rib, and ends at the inferior border of teres major, where it will become the brachial artery. The axillary artery can be said to have 3 parts... 1. Located between the lateral border of the 1st rib and the medial border of the pectoralis minor, and has one branch, the superior thoracic artery 2. Sits posterior to the pectoralis minor, and gives off 2 branches, the thoracoacromial artery and the lateral thoracic artery, which pass medially and laterally to pectoralis minor, respectively 3. Extends past the lateral border of pectoralis minor to the inferior border of the teres major and will give off 3 branches. The subscapular artery (the largest in the axillary artery), the anterior circumflex humeral artery, and the posterior circumflex humeral artery (both of these originate opposite the subscapular artery) The axillary vein is formed by the union of the brachial and basilic veins at the inferior border of teres major. It will also end the lateral border of the 1st rib, where it will become the subclavian vein. The apical lymph nodes are the ultimate destination for lymph entering the axilla. The apical nodes will then drain into the supraclavicular nodes, and finally into the subclavian lymphatic trunk. From here, the path of the lymph will depend on the upper extremity it is coming from, on the right side, the subclavian lymphatic trunk will drain into the right lymphatic duct, or directly into the right venous angle. On the left side, the subclavian trunk will (commonly) drain directly into the thoracic duct 18. Describe the functional deficits resulting from injury to the superior and inferior branchial plexus as well as the terminal branches 1 Question Superior trunk injuries will typically occur from excessive increase of the angle between the neck and shoulder (i.e., the origin point of the plexus) and will result in waiter’s tip position, a characteristic position of the upper extremity where it hangs by the side in the medial position. Another condition that could develop from a supraclavicular branch injury is Erb-Duchenne palsy, the paralysis of the shoulder and arm muscles supplied by C5-C6. It is clinically presented as an abducted shoulder, medially rotated arm, and extended elbow. The patient will also experience loss of sensation in the lateral aspect of the upper extremity. Inferior branch injuries are much less common and are typically seen in grasping to break a fall or if a baby is pulled too hard during delivery. These injuries typically avulse the roots of the spinal nerves of C8- T1 and this will affect the short muscles of the hand, resulting in the condition called claw hand 19. Describe the arteries, veins, and nerves of the arm 1 Question Arterial Supply -The main arterial supply of the arm is from the brachial artery, which is a continuation of the axillary artery, which itself is a continuation of the subclavian artery. The transition start at the inferior border of teres major and ends in the cubital fossa (opposite the neck of the radius and under the bicipital aponeurosis) where it divides into the radial and ulnar arteries. When moving inferolateral, the brachial artery will travel with the median nerve running anterior to it. There are 3 main branches of the brachial artery, those being the profunda brachii (deep artery of the arm) and the superior and inferior ulnar collateral nerves. Venous Supply -The arm has two sets of veins, the superficial and deep that will freely anastomose with each other. The superficial set of veins has two main veins, the cephalic and basilic veins. The branchial vein is two paired deep veins that accompany the brachial artery. The brachial vein ‘begins’ at the elbow with the union of the accompanying veins of the ulnar and radial arteries and will end at the by merging with the basilic vein to form the axillary vein. Both the superficial and deep veins have valves. Nervous Supply -The median nerve is formed in the axilla (armpit) by the union of the lateral and medial roots from the lateral and medial cords of the brachial plexus. It then runs distally in the arm and will go into the cubital fossa, where it will be deep to the bicipital aponeurosis and the median cubital vein. The ulnar nerve will arise from the medial cord of the brachial plexus and goes distal along the median side of the brachial artery, passing posteriorly to the medial epicondyle of the humerus. Note that the median and ulnar nerves do not supply any branches to the arm; however, they will supply branches to the elbow joint. The musculocutaneous nerve will arise from the lateral cord of the brachial plexus and pierce coracobrachialis, and then continue distally between brachialis and the biceps. It will supply all three muscles in the anterior compartment and then exit lateral to the biceps as the lateral cutaneous nerve of the forearm. The radial nerve will follow the profunda brachii artery and curve around the humerus in the radial groove. It supplies the posterior compartments (extensor) of the arm, as well as the forearm (and the overlying skin). The nerves in the arm can be injured by a number of forces and each have a different clinical result. A musculocutaneous injury (often caused by a weapon such as a knife) would result in the paralysis of the muscles it supplies (coracobrachialis, biceps, and brachialis) and thus greatly weakened flexion (and supination) of the forearm. In addition, the lateral side of the forearm could see loss of sensation, due to the lateral cutaneous nerve also being damaged as a result. If the radial nerve is damaged above (superior) to where it forms its branches to the triceps, the triceps, brachioradialis, and supinator and extensor muscles of the wrist and fingers will be paralyzed. There will also be loss of sensation in the skin supplied by the nerve. If the radial nerve is damaged after it gives its branches to the triceps (in the radial groove), the triceps themselves will not be completely paralyzed due to only the median head being affected. The muscles in the posterior compartment of the forearm would still be paralyzed as they are supplied by the more distal branches of the radial nerve. Cubital Fosaa -The cubital fossa is a triangular shaped depression found on the anterior surface of the elbow. It is the passage for many nerves/arteries/veins: the terminal part of the brachial artery and where it splits into the radial and ulnar arteries, the (deep) accompanying veins of the arteries, the bicep brachii tendon, the median nerve, and the radial nerve (divides into superficial and deep branches). There is also subcutaneous tissue (deep fascia) that overlays the cubital fossa, and it contains the median cubital vein, and the medial and lateral cutaneous nerves of the forearm. 20. Describe the muscles of the forearm in terms of their general attachments, innervations, and major actions 2 Questions In general, the forearm’s role is to assist the shoulder in the application of force and control the hand. The flexors and pronators of forearm are found in the anterior compartment and are supplied by the median nerve (except for the muscles of the flexor carpi ularnis (FCU), the ulnar and humeral heads and the medial part of flexor digitorum profundus (FDP), that goes to 4th and 5th fingers). Most of the tendons in the flexor muscles pass over the anterior surface of the wrist and are held there by the palmar carpal ligament and transverse carpal ligament (flexor retinaculum). There are 3 layers (groups) of forearm muscles in the anterior compartment, the superficial (first), the intermediate (second), and the deep (third). The superficial layer contains 4 muscles: pronator teres, flexor carpi radialis (FCR), palmaris longus, and flexor carpi ulnaris (FCU), which all attach to the medial epicondyle of the humerus (common flexor origin) proximally via a common flexor tendon. The intermediate layer (group) only contains one muscle, flexor digitorum superficialis (FDS). The deep group consists of 3 muscles: flexor digitorum profundus (FDP), flexor pollicis longus (FPL), and pronator quadratus. Both the superficial and intermediate groups will cross the elbow joint, while the deep layer will not. The long flexors of the digits, FDS and FDP also serve to flex the metacarpophalangeal and wrist joints. Note that pronator quadratus is the primary pronator. The extensor muscles of the forearm are found in the posterior (extensor-supinator) compartment and every muscle in the compartment is innervated by the radial nerve. The muscles in the posterior compartment can be classified into 3 functional groups. Those being muscles that extend and abduct/adduct the hand (extensor carpi radialis longus (ECRL), extensor carpi radialis brevis (ECRB), and extensor carpi ulnaris (ECU)), the muscles that extend the 4 medial digits (extensor digitorum, extensor indicis, and extensor digiti minimi (EDM)), and muscles that extend/abduct the thumb (abductor pollicis longus (APL), extensor pollicis brevis (EPD), and extensor pollicis longus (EPL)). They can also be classified into superficial and deep layers. All of the superficial extensors will attach to the lateral epicondyle. The extensor tendons are held in the wrist region by the extensor retinaculum and covered with synovial tendon sheaths to reduce friction. 21. Describe the arteries, veins, and nerves of the forearm 1 Question Nerves -There are 3 major nerves found in the forearm, median, ulnar, and radial. The median and ulnar nerves are the only nerves in the anterior (flexor) aspect of the forearm (besides cutaneous nerves). The median nerve is the principal nerve in the anterior compartment and will leave the cubital fossa in between the heads of pronator teres (while branching into it) and then passing deep to flexor digitorum superficialis and continuing distally. It also gives off the anterior interosseous nerve. The ulnar nerve passes posterior to the medial epicondyle of the humerus and becomes superficial at the wrist and runs alongside the medial side of the ulnar artery. It will innervate the skin of the medial side of the hand. The radial nerve, despite appearing in the cubital fossa (anterior side of the elbow), will still innervate the posterior (extensor) compartment of the forearm. In the cubital fossa the radial nerve will divide into deep and superficial branches. The deep branch will arise anterior to the lateral epicondyle and pierce the supinator, before continuing down as the posterior interosseous nerve. The superficial branch of the radial nerve is a cutaneous and articular that goes distally under the brachioradialis and will cross the roof of the anatomical snuff box, where it will innervate the skin of the dorsal surface of the hand. Arteries/Veins -The brachial artery will end at the distal end of the cubital fossa and split into the ulnar and radial arteries, the main arteries of the forearm. The ulnar artery will descend through the anterior portion of the forearm, deep to pronator teres, and end in the hand. The radial artery goes down the lateral side of the forearm, until it wraps around to cross the anatomical snuff box and reach the hand. The forearm has both superficial and deep veins, with the superficial ascending subcutaneous tissue and the deep veins following the deep arteries. 22. Describe the muscles of the hand in terms of their general attachments, innervations, and major actions 1 Question The muscles of the hand can be divided into a number of categories. In the palmar aspect, there are 2 eminences, the more prominent lateral (thumb side) thenar eminence and the medial (5th finger side) hypothenar eminence, separated by a central concavity. The thenar eminence has 3 muscles, abductor pollicis brevis, flexor pollicis brevis, and opponens pollicis. All of the muscles in the thenar compartment are innervated by the median nerve, except for the abductor pollicis. The hypothenar compartment also has 3 muscles, abductor digiti minimi, flexor digiti minimi, and opponens digiti minimi. All 3 of the muscles are innervated by the deep branch of the ulnar nerve. Note how both compartments has muscle that abducts, flexes, and opposes, all movements the digits will do. The fascia over the eminences is relatively thin; however, it will thicken into the palmar aponeurosis centrally and over the fingers as digital sheaths. The aponeurosis functions to cover soft tissue and the long flexor tendons and will form the digital sheaths at its distal end. These fibrous sheaths are tubes that enclose the flexor tendons and their surrounding synovial sheaths as they pass to their respective digits. The medial fibrous septum is the medial border of the aponeurosis and forms part of the wall of the hypothenar compartment, while the lateral fibrous septum is the same for the lateral side and thenar compartment. In between the thenar and hypothenar compartments is the central compartment which contains the flexor tendon (and their sheaths), the lumbricals, the superficial palmar arterial arch, and the vessel and nerves of the digits. The abductor compartment is the deepest of the hand’s compartments and contains abductor pollicis. Note there are 2 potential spaces between the flexor tendons and fascia called the thenar and midpalmar space. The lumbricals (‘worm-like’) are the shortest muscles in the hand and are innervated by both the median (1 and 2) and ulnar (3 and 4) nerves. The interossei (4 dorsal and 3 palmar) sit in between the metacarpals, are innervated by the deep branch of the ulnar nerve and are ad/abductors. Use the DAB and PAD to memorize Dorsal Abduction and Palmar Adduction. Note that there can be a muscle present, palmaris brevis, that is found in the subcutaneous tissue of the hypothenar eminence, not in the compartment itself. It functions to aid in grip and covers the ulnar nerve and artery. It is unique as the only motor muscle innervated by the superficial branch of the ulnar nerve. 23. Describe the arteries, veins, and nerves of the hand 1 Question Arteries/Veins -All of the blood in the hands is provided by the radial and ulnar arteries (and their branches). The ulnar artery enter anterior to the flexor retinaculum and between the pisiform and the hook of hamate in what is called the ‘ulnar canal’ (Guyon canal). It will then give rise to a deep branch and continue superficially to the long flexor tendons where it is the main contributor to the superficial palmar arch. This superficial palmar arch then gives rise to 3 common palmar arteries that will anastomose with palmar metacarpal arteries derived from the deep palmar arch. Every common palmar artery will split into a pair of proper palmar arteries that will run alongside the 2nd- 4th fingers. The radial artery snakes around the lateral side of the radius to cross the anatomical snuff box and then form the deep palmar arch by anastomosing with the ulnar artery. The arch lies across the metacarpals, just distal to their base and gives rise to the 3 palmar metacarpal arteries and the princeps pollicis artery. Note the radialis indicis artery will pass along the lateral (thumb) side of the 2nd finger, ‘paired’ with a proper palmar artery. Nerves -The ulnar nerve leaves the forearm and enters the hand via the Guyon canal (Ulnar canal). It has a deep and superficial branch and gives off the palmar cutaneous branch and the dorsal cutaneous branch. The palmar cutaneous branch will pass superficially over the palmar aponeurosis and innervate the skin on the medial side of the palm. The dorsal cutaneous branch will innervate the medial half of the dorsum and the 5th finger and medial half of the 4th finger. The superficial branch will supply cutaneous nerves to the anterior surface of the medial 1 and half fingers. The deep branch will supply the hypothenar muscles, the two medial lumbricals, the AD, the deep head of FPB, and all of the interossei. Note that the radial nerve will not supply any hand muscles. It will supply the skin and fascia of the lateral two-thirds of the dorsum of the hand, dorsum of the thumb, and the proximal parts of the lateral one and half digits. 24. Describe the structure of the carpal tunnel and its contents 1 Question The carpal tunnel is a passageway for the median nerve, as well as the tendons of flexor digitorum superficialis (FDS), flexor digitorum profundus (FDP), and flexor digitorum longus (FDL), that passes deep to the flexor retinaculum and with the tubercles of the scaphoid and trapezium on the lateral side and the pisiform and hook of hamate on the medial side. At the end of the carpal tunnel, the median nerve supplies two and a half thenar muscles and the 1st and 2nd lumbricals. It will also send sensory fibers to the lateral (thumb side) palmar surface, the sides of the first 3 digits, the lateral side of the 4th digit, and the dorsal surface of the distal half of the aforementioned digits. The palmar cutaneous branch of the median nerve will go over the carpal tunnel, meaning that what is supplies, the central palm, will be unaffected by injuries to the carpal tunnel 25. Describe carpal tunnel syndrome 1 Question Carpal tunnel syndrome refers to any lesion that reduces the space in the carpal tunnel, whether that be by reducing the size of the carpal tunnel itself, or by (more commonly) increasing the size of the structures that pass through it. The median nerve is the most sensitive in the area and is therefore often the most affected. Because of the its two terminal sensory branches, a carpal tunnel injury could result in tingling (paresthesia), diminished sensation (hypesthesia), and absence of tactile sensation (anesthesia) of the lateral 3 and a half digits. Remember that the central palm will remain unaffected due to the palmar cutaneous branch arising before the median nerve enters the carpal tunnel. It also innervates the muscles of the thenar eminence, meaning that carpal tunnel will also result in the progressive loss of coordination and strength in the thumb, this symptom can be known as “ape hand”. A carpal tunnel release can surgically alleviate some of the symptoms of the condition 26. Describe the structure and function of the joints of the pectoral girdle 2 Questions The pectoral girdle refers to the almost circular shape formed by both scapula and the clavicles. There are several joints in the pectoral girdle, the sternoclavicular joint (SC joint), the acromioclavicular joint (AC joint), as well as the scapulothoracic joint (which is not a true joint, but rather a physiological joint), and the glenohumeral joint (shoulder). The sternoclavicular joint is the articulation between the manubrium of the sternum and the sternal end of the clavicle that is classified as a saddle type joint, but functions as a ball-and-socket joint. The joint is divided into compartments by an articular disc that is attached to two intrinsic ligaments, anterior and posterior SC ligaments. The is also an interclavicular ligament that sits superior to the clavicles and holds them together, and a costoclavicular ligament that attaches the inferior surface of the clavicle to the costal cartilage of the 1st rib to prevent elevation of the clavicle. The SC joint is the only place where the appendicular skeleton articulates with the axial skeleton. The acromioclavicular joint (AC joint) is a synovial articulation between the acromion of the scapula and the acromial end of the clavicle. There is a superior AC ligament that will stretch across the superior connection points and strengthen the joint. There is also a coracoclavicular ligament that will maintain the integrity of the AC joint. It is subdivided into conoid and trapezoid ligaments and is found where the clavicle anchors to the coracoid process of the scapula. As mentioned, the scapulothoracic joint is not a ‘true joint’ because there is no connection point (i.e., joint capsule), but it is considered a physiological joint because the scapula will still articulate relative to the clavicle. The glenohumeral joint is the articulation between the head of the humerus and the glenoid cavity found in the scapula. The glenoid cavity is ‘deepened’ by the fibrocartilaginous glenoid labrum which can be thought of as O-ring that keeps the larger head of humerus more or less in place in the smaller cavity. Holding the humeral head in place are the 4 muscles that make up the rotator cuff (supraspinatus, infraspinatus, teres minor, and subscapularis). There is also a loose, fibrous joint capsule that surrounds the joint and is attached medially at the glenoid cavity and laterally at the anatomical neck of the humerus. It serves to enclose/protect the proximal attachment of the (long head) of biceps brachii. The inferior aspect of the joint capsule is the weakest because it is not supported by the rotator cuff. The glenohumeral and coracohumeral ligaments support the structure of the joint capsule anteriorly and posteriorly, respectively. The transverse humeral ligament is a broad, fibrous ligament that sits between the tubercles of the humerus and helps turn the intertubercular sulcus (groove) into a canal that holds the long head of bicep brachii. The coracoid process, coracoacromial ligament, and acromion form what is called the coracoacromial arch which serves to prevent superior dislocation of the humeral head. Note the presence of a couple bursas in the pectoral girdle that can become irritated (subacromial and subscapular). The overall purpose of the glenohumeral joint is to allow the hand to position freely in all 3 planes of motion. 27. Describe rotator cuff injuries 1 Question Injuries to the rotator cuff typically occur with repetitive use above the horizontal, such as in sports. One of the main areas affected is the relatively avascular supraspinatus tendon. Supraspinatus is responsible for the first 15o of abduction in the shoulder and if a person has torn their rotator cuff, they will not be able to begin abduction of the arm. 28. Describe dislocation of the acromioclavicular and glenohumeral joints 1 Question AC joint dislocation- The dislocation of the AC joint will typically come from falling directly on the shoulder or bracing oneself with the elbow. It is referred to as a ‘shoulder separation’ when the AC and coracoclavicular ligaments are torn. It is considered more severe when both are torn, because a tear in the AC joint will result in the AC joint disarticulating; however, if the coracoclavicular ligament is torn as well, then the clavicle will move superiorly to the acromion Glenohumeral joint dislocation- The typical dislocation of the humeral head from the glenoid cavity will occur in the inferior direction, but clinically it is referred to as anterior (or more rarely, posterior) to describe the position of the humeral head relative to the long head of the triceps. The typical mechanism for dislocation is excessive extension and lateral rotation of the humerus. The axillary nerve can be in danger in this situation because it wraps around the humerus in the area of the joint capsule.
