Anatomy Course Module 4 Sample

Module Four Course Index

Lesson 1:

Regions and bones of the upper limb

Lesson 2:

Posterior axioappendicular muscles

Quiz

Lesson 3:

Intrinsic shoulder muscles

Quiz

Lesson 4:

Anterior axioappendicular muscles

Quiz

Module Four Lesson One

Bones of Regions of the Upper Limb

Regions of the upper limb The upper limb is characterized by its mobility and ability to grasp, strike, and conduct fine motor skills (manipulation). These characteristics are especially marked in the hand when performing manual activities such as buttoning a shirt.

Synchronized interplay occurs between the joints of the upper limb to coordinate the intervening segments to perform smooth, efficient motion at the most workable distance or position required for a specific task. Efficiency of hand function results in large part from the ability to place it in the proper position by movements at the scapulothoracic, glenohumeral elbow, radio-ulnar, and wrist joints.

The upper limb consists of four major segments, which are further subdivided into regions for precise description, (see Image one): 1. Shoulder: proximal segment of the limb that overlaps parts of the trunk (thorax and back) and lower lateral neck. It includes the pectoral, scapular, and deltoid regions of the upper limb, and the lateral part (greater supraclavicular fossa) of the lateral cervical region. It overlies half of the pectoral girdle. The pectoral (shoulder) girdle is a bony ring, incomplete posteriorly, formed by the scapulae and clavicles and completed anteriorly by the manubrium of the sternum (part of the axial skeleton).

2. Arm (L. brachium): first segment of the free upper limb (more mobile part of the upper limb independent of the trunk) and the longest segment of the limb. It extends between and connects the shoulder and the elbow and consists of anterior and posterior regions of the arm, centered around the humerus.

3. Forearm (L. antebrachium): second longest segment of the limb. It extends between and connects the elbow and the wrist and includes anterior and posterior regions of the forearm overlying the radius and ulna.

4. Hand (L. manus): part of the upper limb distal to the forearm that is formed around the carpus, metacarpus, and phalanges. It is composed of the wrist, palm, dorsum of hand, and digits (fingers, including an opposable thumb) and is richly supplied with sensory endings for touch, pain, and temperature.

The Hand will not be covered in this course but will be available in future as an optional module.

Humerus • The humerus (arm bone), the largest bone in the upper limb, articulates with the scapula at the glenohumeral joint and the radius and ulna at the elbow joint • The proximal end of the humerus has a head, surgical and anatomical necks, and greater and lesser tubercles. See Image 8 • The spherical head of the humerus articulates with the glenoid cavity of the scapula.

• The anatomical neck of the humerus is formed by the groove circumscribing the head and separating it from the greater and lesser tubercles.

• It indicates the line of attachment of the glenohumeral joint capsule.

• The surgical neck of the humerus, a common site of fracture, is the narrow part distal to the head and tubercles .

• The junction of the head and neck with the shaft of the humerus is indicated by the greater and lesser tubercles, which provide attachment and leverage to some scapulohumeral muscles.

• The greater tubercle is at the lateral margin of the humerus, whereas the lesser tubercle projects anteriorly from the bone.

• The intertubercular (bicipital) groove separates the tubercles and provides protected passage for the slender tendon of the long head of the biceps muscle.

IMAGE 8

Image 8. The proximal Humerus with several features highlighted.

SEARCH TIP From your hub/home screen, enter humerus into your search bar and select “screens.” You will have a choice of several screen options with for example the “Proximal humerus,” or “review of the bones of the arm-humerus.”

You can also select “Videos” to watch short presentations about the important features of the humerus.

IMAGE 9

Image 9. The proximal Humerus with several features highlighted. On your 3D program, click on the tabs to explore features.

The shaft of the humerus • has two prominent features: the deltoid tuberosity laterally, for attachment for the deltoid muscle, and • the oblique radial groove (groove for radial nerve, spiral groove) posteriorly, in which the radial nerve and deep artery of the arm lie as they pass anterior to the long head and between the medial and the lateral heads of the triceps brachii muscles.

• The inferior end of the humeral shaft widens as the sharp medial and lateral supraepicondylar (supracondylar) ridges form and then end distally in the especially prominent medial epicondyle and the lateral epicondyle, providing for muscle attachment.

The distal end of the humerus • including the trochlea; the capitulum; and the olecranon, coronoid, and radial fossae – makes up the condyle of the humerus • The condyle has two articular surfaces: a lateral capitulum (L. little head) for articulation with the head of the radius and a medial, spool-shaped or pulley-like trochlea (L. pulley) for articulation with the proximal end (trochlear notch) of the ulna.

• Two hollows, or fossae, occur back to back superior to the trochlea, making the condyle quite thin between the epicondyles.

• Anteriorly, the coronoid fossa receives the coronoid process of the ulna during full flexion of the elbow.

• Posteriorly, the olecranon fossa accommodates the olecranon of the ulna during full extension of the elbow.

• Superior to the capitulum anteriorly, a shallower radial fossa accommodates the edge of the head of the radius when the forearm is fully flexed.

Module Four Lesson Two

Posterior Axioappendicular Muscles Extrinsic Back Muscles

Anatomy • The Axioappendicular muscles are the muscles that extend between the axial (See Image C) and (superior or inferior) appendicular skeletons. (Images A & B) • There are two groups, the anterior axioappendicular muscles and the posterior axioappendicular muscles.

• The posterior axioappendicular muscles are further subdivided into two groups: superficial and intermediate • The superficial attach the superior appendicular skeleton (of the upper limb) to the axial skeleton (in the trunk).

IMAGE A

IMAGE B

Image A & B. show the appendicular skeleton highlighted in green.

IMAGE C

Image C. The axial skeleton comprised of the skull, hyoid, vertebral column, thoracic cage, sacrum and coccyx

Table 1. Posterior axioappendicular muscles Muscle

Proximal Attachment

Distal Attachment

Innervation1

Main Action(s)

Superficial posterior axioappendicular (extrinsic shoulder) muscles Trapezius

Medial third of superior nuchal line; external occipital protuberance; nuchal ligament; spinous processes of C7-T12 vertebrae

Lateral third of clavicle; acromion and spine of scapula

Spinal accessory nerve (CN XI) (motor fibers) and C3, C4 spinal nerves (pain and proprioceptive fibers)

Descending part elevates; ascending part depresses; and middle part (or all parts together) retracts scapula; descending and ascending parts act together to rotates glenoid cavity superiorly

Latissimus dorsi

Spinous processes of inferior 6 thoracic vertebrae, thoracolumbar fascia, iliac crest, and inferior 3 or 4 ribs

Floor of intertubercular sulcus of humerus

Thoracodorsal nerve (C6, C7, C8)

Extends, adducts, and medially rotates humerus; raises body toward arms during climbing

Levator scapulae

Posterior tubercles of transverse processes of C1-C4 vertebrae

Medial border of scapula superior to root of scapular spine

Dorsal scapular (C5) and cervical (C3, C4) nerves

Elevates scapula and tilts its glenoid cavity inferiorly by rotating scapula

Rhomboid minor and major

Minor: nuchal ligament; spinous processes of C7 and T1 vertebrae

Minor: smooth triangular area at medial end of scapular spine

Dorsal scapular nerve (C4,C5)

Retract scapula and rotate it to depress glenoid cavity; fix scapula to thoracic wall

Major: spinous processes of T2-T5 vertebrae

Major: medial border of scapula from level of spine to inferior angle

The spinal cord segmental innervation is indicated (e.g., “C4, C5� means that the nerves supplying the rhomboids are derived from the fourth and fifth cervical segments of the spinal cord). Numbers in boldface (C5) indicate the main segmental innervation. Damage to one or more of the listed spinal cord segments or to the motor nerve roots arising from them results in paralysis of the muscles concerned.

1

SEARCH TIP Enter humerus into your search bar and select “screens.” You will have a choice of several screen options with for example the “Proximal humerus,” or “review of the bones of the arm-humerus.”

You can also select “Videos” to watch short presentations about the important features of the humerus.

IMAGE 9

Image 9. The proximal Humerus with several features highlighted. On your 3D program, click on the tabs to explore features.

App: Click or copy this link to view a 4.30min video on the post. app muscleshttps://3d4medic.al/NncvsqmU The superficial posterior axioappendicular muscles are: • latissimus dorsi • levator scapulae • rhomboids • trapezius • They are posterior axioappendicular muscles that connect the axial skeleton (vertebral column) with the superior appendicular skeleton (pectoral girdle and humerus) • Produce and control limb movements • levator scapulae and rhomboids are sometimes categorized as Deep posterior axioappendicular (extrinsic shoulder) muscles • Although located in the back region for the most part these muscles receive their nerve supply from the anterior rami of cervical nerves and act on the upper limb.

See image 1.

IMAGE 1

Image 1. Superficial posterior axioappendicular muscles /extrinsic back muscles

IMAGE D

Image D. UT-Upper traps, DEL-deltoids, MT-middle traps, LT-lower traps/ inferior fibers, SA-serratus anterior

IMAGE 5

• The trapezius also braces the shoulders by pulling the scapulae posteriorly and superiorly, fixing them in position to the thoracic wall with tonic contraction; consequently, weakness of this muscle causes drooping of the shoulders.

To test the trapezium (or the function of the spinal accessory nerve [CN XI] that supplies it), the shoulder is shrugged against resistance (the person attempts to raise the shoulders as the examiner presses down on them). If the muscle is acting normally, the superior border of the muscle can be easily seen and palpated.

Image 5. Middle fibers of trapezius

IMAGE 15

Image 15.

The rhomboid major

IMAGE 16

Image 16.

The rhomboid minor

Quiz!

Click on this link to complete your quiz: https://www.pilateskinesiology.com/posterioraxioappendicularmusclesquiz

Deltoid • The deltoid is a thick, powerful, coarse-textured muscle covering the shoulder • Forms a rounded contour (Images 1-5).

• As its name indicates the deltoid is shaped like the inverted Greek letter delta (Δ).

• The muscle is divided into unipennate fibers-anterior and posterior parts can act separately or as a whole.

• When all three parts of the deltoid contract simultaneously, the arm is abducted.

• The anterior and posterior parts act like guy ropes to steady the arm as it is abducted.

• To initiate movement during the first 15° of abduction, the deltoid is assisted by the supraspinatus.

• When the arm is fully adducted, the line of pull of the deltoid coincides with the axis of the humerus; thus it pulls directly upward on the bone and cannot initiate or produce abduction (Image A below). The deltoid becomes fully effective as an abductor after the initial 15° of abduction.

IMAGE A

Image A. When the arm is fully adducted, the line of pull of the deltoid coincides with the axis of the humerus; thus it pulls directly upward on the bone and cannot initiate or produce abduction.

It relies upon the supraspinatus to initiate the first 15 degrees of abduction.

Rotator cuff muscles IMAGE 8

Image 8. Posterior view of rotator cuff muscles

IMAGE 7

To test the serratus anterior (or the function of the long thoracic nerve that supplies it), the hand of the outstretched limb is pushing against a wall. If the muscle is acting normally, several digitations of the muscle can be seen and palpated.

Image 7. The serratus anterior IMAGE 8

Image 8. The serratus anterior lateral perspective

IMAGE 9

Image 9. The serratus anterior anterior perspective