ZOO 4990L - Gross Anatomy Lab III

Dissections of September 11 - 13, 2001

N.B.		In each dissection some names appear in parentheses. These are structures that may not readily be found during your dissection, i.e., look for them but do not spend too much time on them so that you have time to comlete the laboratory. Many of these structures will be exposed more completely in future dissections or are best observed in your atlas. Also, there will be important structures listed that are not found in your dissector (Hansen, 1998); information about these items can be found in your text (Jenkins, 1998; Moor and Augur, 1996; Stern, 1997).

PECTORAL REGION; ANTERIOR THORACIC WALL (Ch. 1; pp. 1-6)

Dissection notes

Contrá figure in dissector, need to skin cranial to clavicles to expose pectoralis major; need not encircle nipples
Skip dissection of breast (Section C)
Contrá dissectior, innermost intercostals cannot be seen in this dissection; these will be examined in posterior mediastinum
Modify the breastplate cuts to expand opening; detach serratus anterior from its attachments to ribs 2-6, leaving attachments to ribs 7 & 8; then cut ribs 2-6 close to mid-axillary line
Contrá your text, it is well established that both pectoral muscles (major and minor) are innervated by both pectoral nerves (medial and lateral) ); moreover, the only way to unambiguously distinguish the medial and lateral pectoral nerves is to trace them back to their cord of origin

landmarks/regions
	
	suprasternal notch (jugular notch)
	sternal angle
	deltopectoral triangle

osteology
	clavicle
	scapula
		coracoid process

myology
	pectoralis major
	pectoralis minor
	serratus anterior
	external intercostal
	internal intercostal
	(innermost intercostal)
	transversus thoracis

angiology
	cephalic 
	axillary a
		thoracoacromial a
	anterior intercostal a 
	anterior intercostal v
	(posterior intercostal a)
	(posterior intercostal v)
	internal thoracic a
	internal thoracic v

neurology
	lateral pectoral n
	medial pectoral n
	(intercostal nn)

SUPERIOR MEDIASTINUM (Chap. 1; pp. 16-7)

Dissection notes

The sternum will be reflected using a technique different from that described in your text (Section B., p. 16); your instructors will assist:
- 1. Cut the first rib (R1) lateral to the insertion of the subclavius muscle and medial to where the axillary artery and vein cross it (see Netter Plate 175).
- 2. Cut the clavicle at the junction of the attachment of the deltoid and pectoralis major muscle. Make these cuts bilaterally and then gently rotate the sternum cranially, freeing any soft tissue adhesions.

landmarks/regions
	superior mediastinum

angiology
	subclavian v
	internal jugular v
		brachiocephalic vv
			superior vena cava
	azygos v
	aorta
		ascending aorta
		arch of the aorta
			brachiocephalic trunk
			left common carotid a
			left subclavian a
		descending aorta
	pulmonary trunk
	ligamentum arteriosum (remnant of ductus arteriosum)

neurology
	phrenic n
	vagus (CN X) n
		l. recurrent laryngeal n

splanchnology
	(thymus gland)

POSTERIOR TRIANGLE OF THE NECK (pp. 123-127)

Dissection notes

In contrast to other regions of the body, it is important that only the skin be removed in skinning the neck and head; i.e., the superficial fascia must be left intact. Ask your instructor for assistance; a good guide to the proper depth in the neck will be the platysma muscle.
Due to its tough fascia, the posterior triangle is a difficult dissection requiring both care and patience. Particularly challenging is finding the cutaneous branches of the cervical plexus; be careful when skinning along the posterior border of sternocleidomastoid as to avoid cutting these superficial nerves (see Netter Plate 18 or Grant 8.4).
Portions of your cadaver's clavicle may already have been removed (p. 125; Section C); check with your instructor before proceeding with this section.. Also, contrá the dissector it is not necessary to remove the subclavius muscle.

atlas (see Grant 8.44 or Netter Plate 30)
	investing fascia
	pretrachieal fascia
	prevertebral fascia

landmarks/regions
	posterior triangle

myology
	sternocleidomastoid
	trapezius
	platysma
	(subclavius)
	omohyoid
	splenius 
	levator scapulae
	scalenus anterior
	scalenus medius
	scalenus posterior

neurology
	cervical plexus
		lesser occipital n
		great auricular n
		transverse cervical n
		supraclavicular nn
		phrenic n
	accessory n (CN XI)

angiology
	external jugular v
	subclavian v
	subclavian a
		(transverse cervical a)
		(suprascapular a)

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